Man page of SCONS

# SCONS

Section: User Commands (1)
Updated: March 2008
Index Return to Main Contents

## NAME

scons - a software construction tool

## SYNOPSIS

scons [ options... ] [ name=val... ] [ targets... ]

## DESCRIPTION

The scons utility builds software (or other files) by determining which component pieces must be rebuilt and executing the necessary commands to rebuild them.

By default, scons searches for a file named SConstruct, Sconstruct, or sconstruct (in that order) in the current directory and reads its configuration from the first file found. An alternate file name may be specified via the -f option.

The SConstruct file can specify subsidiary configuration files using the SConscript() function. By convention, these subsidiary files are named SConscript, although any name may be used. (Because of this naming convention, the term "SConscript files" is sometimes used to refer generically to all scons configuration files, regardless of actual file name.)

The configuration files specify the target files to be built, and (optionally) the rules to build those targets. Reasonable default rules exist for building common software components (executable programs, object files, libraries), so that for most software projects, only the target and input files need be specified.

Before reading the SConstruct file, scons adds looks for a dir named site_scons in the dir containing the SConstruct file; it adds that site_scons to sys.path, reads the file site_scons/site_init.py, and adds the directory site_scons/site_tools to the default toolpath, if those exist. See the --no-site-dir and --site-dir options for more details.

scons reads and executes the SConscript files as Python scripts, so you may use normal Python scripting capabilities (such as flow control, data manipulation, and imported Python libraries) to handle complicated build situations. scons, however, reads and executes all of the SConscript files before it begins building any targets. To make this obvious, scons prints the following messages about what it is doing:

      $ scons foo.out
      scons: Reading SConscript files ...
      scons: done reading SConscript files.
      scons: Building targets  ...
      cp foo.in foo.out
      scons: done building targets.
      $

The status messages (everything except the line that reads "cp foo.in foo.out") may be suppressed using the -Q option.

scons does not automatically propagate the external environment used to execute scons to the commands used to build target files. This is so that builds will be guaranteed repeatable regardless of the environment variables set at the time scons is invoked. This also means that if the compiler or other commands that you want to use to build your target files are not in standard system locations, scons will not find them unless you explicitly set the PATH to include those locations. Whenever you create an scons construction environment, you can propagate the value of PATH from your external environment as follows:

      import os
      env = Environment(ENV = {'PATH' : os.environ['PATH']})

Similarly, if the commands use external environment variables like $PATH, $HOME, $JAVA_HOME, $LANG, $SHELL, $TERM, etc., these variables can also be explicitly propagated:

      import os
      env = Environment(ENV = {'PATH' : os.environ['PATH'],
                               'HOME' : os.environ['HOME']})

Or you may explicitly propagate the invoking user's complete external environment:

      import os
      env = Environment(ENV = os.environ)

This comes at the expense of making your build dependent on the user's environment being set correctly, but it may be more convenient for many configurations.

scons can scan known input files automatically for dependency information (for example, #include statements in C or C++ files) and will rebuild dependent files appropriately whenever any "included" input file changes. scons supports the ability to define new scanners for unknown input file types.

scons knows how to fetch files automatically from SCCS or RCS subdirectories using SCCS, RCS or BitKeeper.

scons is normally executed in a top-level directory containing a SConstruct file, optionally specifying as command-line arguments the target file or files to be built.

By default, the command

      scons

will build all target files in or below the current directory. Explicit default targets (to be built when no targets are specified on the command line) may be defined the SConscript file(s) using the Default() function, described below.

Even when Default() targets are specified in the SConscript file(s), all target files in or below the current directory may be built by explicitly specifying the current directory (.) as a command-line target:

      scons .

Building all target files, including any files outside of the current directory, may be specified by supplying a command-line target of the root directory (on POSIX systems):

      scons /

or the path name(s) of the volume(s) in which all the targets should be built (on Windows systems):

      scons C:\ D:\

To build only specific targets, supply them as command-line arguments:

      scons foo bar

in which case only the specified targets will be built (along with any derived files on which they depend).

Specifying "cleanup" targets in SConscript files is not usually necessary. The -c flag removes all files necessary to build the specified target:

      scons -c .

to remove all target files, or:

      scons -c build export

to remove target files under build and export. Additional files or directories to remove can be specified using the Clean() function. Conversely, targets that would normally be removed by the -c invocation can be prevented from being removed by using the NoClean() function.

A subset of a hierarchical tree may be built by remaining at the top-level directory (where the SConstruct file lives) and specifying the subdirectory as the target to be built:

      scons src/subdir

or by changing directory and invoking scons with the -u option, which traverses up the directory hierarchy until it finds the SConstruct file, and then builds targets relatively to the current subdirectory:

      cd src/subdir
      scons -u .

scons supports building multiple targets in parallel via a -j option that takes, as its argument, the number of simultaneous tasks that may be spawned:

      scons -j 4

builds four targets in parallel, for example.

scons can maintain a cache of target (derived) files that can be shared between multiple builds. When caching is enabled in a SConscript file, any target files built by scons will be copied to the cache. If an up-to-date target file is found in the cache, it will be retrieved from the cache instead of being rebuilt locally. Caching behavior may be disabled and controlled in other ways by the --cache-force, --cache-disable, and --cache-show command-line options. The --random option is useful to prevent multiple builds from trying to update the cache simultaneously.

Values of variables to be passed to the SConscript file(s) may be specified on the command line:

      scons debug=1 .

These variables are available in SConscript files through the ARGUMENTS dictionary, and can be used in the SConscript file(s) to modify the build in any way:

      if ARGUMENTS.get('debug', 0):
          env = Environment(CCFLAGS = '-g')
      else:
          env = Environment()

The command-line variable arguments are also available in the ARGLIST list, indexed by their order on the command line. This allows you to process them in order rather than by name, if necessary. ARGLIST[0] returns a tuple containing (argname, argvalue). A Python exception is thrown if you try to access a list member that does not exist.

scons requires Python version 1.5.2 or later. There should be no other dependencies or requirements to run scons.

By default, scons knows how to search for available programming tools on various systems. On Windows systems, scons searches in order for the Microsoft Visual C++ tools, the MinGW tool chain, the Intel compiler tools, and the PharLap ETS compiler. On OS/2 systems, scons searches in order for the OS/2 compiler, the GCC tool chain, and the Microsoft Visual C++ tools, On SGI IRIX, IBM AIX, Hewlett Packard HP-UX, and Sun Solaris systems, scons searches for the native compiler tools (MIPSpro, Visual Age, aCC, and Forte tools respectively) and the GCC tool chain. On all other platforms, including POSIX (Linux and UNIX) platforms, scons searches in order for the GCC tool chain, the Microsoft Visual C++ tools, and the Intel compiler tools. You may, of course, override these default values by appropriate configuration of Environment construction variables.

## OPTIONS

In general, scons supports the same command-line options as GNU make, and many of those supported by cons.

-b
  Ignored for compatibility with non-GNU versions of make.

-c, --clean, --remove
  Clean up by removing all target files for which a construction command is specified. Also remove any files or directories associated to the construction command using the Clean() function. Will not remove any targets specified by the NoClean() function.

--cache-debug=file
  Print debug information about the CacheDir() derived-file caching to the specified file. If file is - (a hyphen), the debug information are printed to the standard output. The printed messages describe what signature file names are being looked for in, retrieved from, or written to the CacheDir() directory tree.

--cache-disable, --no-cache
  Disable the derived-file caching specified by CacheDir(). scons will neither retrieve files from the cache nor copy files to the cache.

--cache-force, --cache-populate
  When using CacheDir(), populate a cache by copying any already-existing, up-to-date derived files to the cache, in addition to files built by this invocation. This is useful to populate a new cache with all the current derived files, or to add to the cache any derived files recently built with caching disabled via the --cache-disable option.

--cache-show
  When using CacheDir() and retrieving a derived file from the cache, show the command that would have been executed to build the file, instead of the usual report, "Retrieved `file' from cache." This will produce consistent output for build logs, regardless of whether a target file was rebuilt or retrieved from the cache.

--config=mode
  This specifies how the Configure call should use or generate the results of configuration tests. The option should be specified from among the following choices:

--config=auto
  scons will use its normal dependency mechanisms to decide if a test must be rebuilt or not. This saves time by not running the same configuration tests every time you invoke scons, but will overlook changes in system header files or external commands (such as compilers) if you don't specify those dependecies explicitly. This is the default behavior.

--config=force
  If this option is specified, all configuration tests will be re-run regardless of whether the cached results are out of date. This can be used to explicitly force the configuration tests to be updated in response to an otherwise unconfigured change in a system header file or compiler.

--config=cache
  If this option is specified, no configuration tests will be rerun and all results will be taken from cache. Note that scons will still consider it an error if --config=cache is specified and a necessary test does not yet have any results in the cache.

-C directory, --directory=directory
  Change to the specified directory before searching for the SConstruct, Sconstruct, or sconstruct file, or doing anything else. Multiple -C options are interpreted relative to the previous one, and the right-most -C option wins. (This option is nearly equivalent to -f directory/SConstruct, except that it will search for SConstruct, Sconstruct, or sconstruct in the specified directory.)

-D
  Works exactly the same way as the -u option except for the way default targets are handled. When this option is used and no targets are specified on the command line, all default targets are built, whether or not they are below the current directory.

--debug=type
  Debug the build process. type specifies what type of debugging:

--debug=count
  Print how many objects are created of the various classes used internally by SCons before and after reading the SConscript files and before and after building targets. This is not supported when run under Python versions earlier than 2.1, when SCons is executed with the Python -O (optimized) option, or when the SCons modules have been compiled with optimization (that is, when executing from *.pyo files).

--debug=dtree
  A synonym for the newer --tree=derived option. This will be deprecated in some future release and ultimately removed.

--debug=explain
  Print an explanation of precisely why scons is deciding to (re-)build any targets. (Note: this does not print anything for targets that are not rebuilt.)

--debug=findlibs
  Instruct the scanner that searches for libraries to print a message about each potential library name it is searching for, and about the actual libraries it finds.

--debug=includes
  Print the include tree after each top-level target is built. This is generally used to find out what files are included by the sources of a given derived file:

        $ scons --debug=includes foo.o

--debug=memoizer
  Prints a summary of hits and misses using the Memoizer, an internal subsystem that counts how often SCons uses cached values in memory instead of recomputing them each time they're needed. Only available when using Python 2.2 or later.

--debug=memory
  Prints how much memory SCons uses before and after reading the SConscript files and before and after building targets.

--debug=nomemoizer
  A deprecated option preserved for backwards compatibility.

--debug=objects
  Prints a list of the various objects of the various classes used internally by SCons. This only works when run under Python 2.1 or later.

--debug=pdb
  Re-run SCons under the control of the pdb Python debugger.

--debug=presub
  Print the raw command line used to build each target before the construction environment variables are substituted. Also shows which targets are being built by this command. Output looks something like this:

        $ scons --debug=presub
        Building myprog.o with action(s):
          $SHCC $SHCFLAGS $SHCCFLAGS $CPPFLAGS $_CPPINCFLAGS -c -o $TARGET $SOURCES

--debug=stacktrace
  Prints an internal Python stack trace when encountering an otherwise unexplained error.

--debug=stree
  A synonym for the newer --tree=all,status option. This will be deprecated in some future release and ultimately removed.

--debug=time
  Prints various time profiling information: the time spent executing each individual build command; the total build time (time SCons ran from beginning to end); the total time spent reading and executing SConscript files; the total time spent SCons itself spend running (that is, not counting reading and executing SConscript files); and both the total time spent executing all build commands and the elapsed wall-clock time spent executing those build commands. (When scons is executed without the -j option, the elapsed wall-clock time will typically be slightly longer than the total time spent executing all the build commands, due to the SCons processing that takes place in between executing each command. When scons is executed with the -j option, and your build configuration allows good parallelization, the elapsed wall-clock time should be significantly smaller than the total time spent executing all the build commands, since multiple build commands and intervening SCons processing should take place in parallel.)

--debug=tree
  A synonym for the newer --tree=all option. This will be deprecated in some future release and ultimately removed.

--diskcheck=types
  Enable specific checks for whether or not there is a file on disk where the SCons configuration expects a directory (or vice versa), and whether or not RCS or SCCS sources exist when searching for source and include files. The types argument can be set to: all, to enable all checks explicitly (the default behavior); none, to disable all such checks; match, to check that files and directories on disk match SCons' expected configuration; rcs, to check for the existence of an RCS source for any missing source or include files; sccs, to check for the existence of an SCCS source for any missing source or include files. Multiple checks can be specified separated by commas; for example, --diskcheck=sccs,rcs would still check for SCCS and RCS sources, but disable the check for on-disk matches of files and directories. Disabling some or all of these checks can provide a performance boost for large configurations, or when the configuration will check for files and/or directories across networked or shared file systems, at the slight increased risk of an incorrect build or of not handling errors gracefully (if include files really should be found in SCCS or RCS, for example, or if a file really does exist where the SCons configuration expects a directory).

--duplicate=ORDER
  There are three ways to duplicate files in a build tree: hard links, soft (symbolic) links and copies. The default behaviour of SCons is to prefer hard links to soft links to copies. You can specify different behaviours with this option. ORDER must be one of hard-soft-copy (the default), soft-hard-copy, hard-copy, soft-copy or copy. SCons will attempt to duplicate files using the mechanisms in the specified order.

-f file, --file=file, --makefile=file, --sconstruct=file
  Use file as the initial SConscript file.

-h, --help
  Print a local help message for this build, if one is defined in the SConscript file(s), plus a line that describes the -H option for command-line option help. If no local help message is defined, prints the standard help message about command-line options. Exits after displaying the appropriate message.

-H, --help-options
  Print the standard help message about command-line options and exit.

-i, --ignore-errors
  Ignore all errors from commands executed to rebuild files.

-I directory, --include-dir=directory
  Specifies a directory to search for imported Python modules. If several -I options are used, the directories are searched in the order specified.

--implicit-cache
  Cache implicit dependencies. This causes scons to use the implicit (scanned) dependencies from the last time it was run instead of scanning the files for implicit dependencies. This can significantly speed up SCons, but with the following limitations:
  scons will not detect changes to implicit dependency search paths (e.g. CPPPATH, LIBPATH) that would ordinarily cause different versions of same-named files to be used.
  scons will miss changes in the implicit dependencies in cases where a new implicit dependency is added earlier in the implicit dependency search path (e.g. CPPPATH, LIBPATH) than a current implicit dependency with the same name.

--implicit-deps-changed
  Forces SCons to ignore the cached implicit dependencies. This causes the implicit dependencies to be rescanned and recached. This implies --implicit-cache.

--implicit-deps-unchanged
  Force SCons to ignore changes in the implicit dependencies. This causes cached implicit dependencies to always be used. This implies --implicit-cache.

--interactive
  Starts SCons in interactive mode. The SConscript files are read once and a scons>>> prompt is printed. Targets may now be rebuilt by typing commands at interactive prompt without having to re-read the SConscript files and re-initialize the dependency graph from scratch.

  SCons interactive mode supports the following commands:

    build[OPTIONS] [TARGETS] ...
      Builds the specified TARGETS (and their dependencies) with the specified SCons command-line OPTIONS. b and scons are synonyms.

      The following SCons command-line options affect the build command:

            --cache-debug=FILE
            --cache-disable, --no-cache
            --cache-force, --cache-populate
            --cache-show
            --debug=TYPE
            -i, --ignore-errors
            -j N, --jobs=N
            -k, --keep-going
            -n, --no-exec, --just-print, --dry-run, --recon
            -Q
            -s, --silent, --quiet
            -s, --silent, --quiet
            --taskmastertrace=FILE
            --tree=OPTIONS

      Any other SCons command-line options that are specified do not cause errors but have no effect on the build command (mainly because they affect how the SConscript files are read, which only happens once at the beginning of interactive mode).

    clean[OPTIONS] [TARGETS] ...
      Cleans the specified TARGETS (and their dependencies) with the specified options. c is a synonym. This command is itself a synonym for build --clean

    exit
      Exits SCons interactive mode. You can also exit by terminating input (CTRL+D on UNIX or Linux systems, CTRL+Z on Windows systems).

    help[COMMAND]
      Provides a help message about the commands available in SCons interactive mode. If COMMAND is specified, h and ? are synonyms.

    shell[COMMANDLINE]
      Executes the specified COMMANDLINE in a subshell. If no COMMANDLINE is specified, executes the interactive command interpreter specified in the SHELL environment variable (on UNIX and Linux systems) or the COMSPEC environment variable (on Windows systems). sh and ! are synonyms.

    version
      Prints SCons version information.

  An empty line repeats the last typed command. Command-line editing can be used if the readline module is available.

        $ scons --interactive
        scons: Reading SConscript files ...
        scons: done reading SConscript files.
        scons>>> build -n prog
        scons>>> exit

-j N, --jobs=N
  Specifies the number of jobs (commands) to run simultaneously. If there is more than one -j option, the last one is effective.

-k, --keep-going
  Continue as much as possible after an error. The target that failed and those that depend on it will not be remade, but other targets specified on the command line will still be processed.

-m
  Ignored for compatibility with non-GNU versions of make.

--max-drift=SECONDS
  Set the maximum expected drift in the modification time of files to SECONDS. This value determines how long a file must be unmodified before its cached content signature will be used instead of calculating a new content signature (MD5 checksum) of the file's contents. The default value is 2 days, which means a file must have a modification time of at least two days ago in order to have its cached content signature used. A negative value means to never cache the content signature and to ignore the cached value if there already is one. A value of 0 means to always use the cached signature, no matter how old the file is.

-n, --just-print, --dry-run, --recon
  No execute. Print the commands that would be executed to build any out-of-date target files, but do not execute the commands.

--no-site-dir
  Prevents the automatic addition of the standard site_scons dir to sys.path. Also prevents loading the site_scons/site_init.py module if it exists, and prevents adding site_scons/site_tools to the toolpath.

--profile=file
  Run SCons under the Python profiler and save the results in the specified file. The results may be analyzed using the Python pstats module.

-q, --question
  Do not run any commands, or print anything. Just return an exit status that is zero if the specified targets are already up to date, non-zero otherwise.
-Q
  Quiets SCons status messages about reading SConscript files, building targets and entering directories. Commands that are executed to rebuild target files are still printed.

--random
  Build dependencies in a random order. This is useful when building multiple trees simultaneously with caching enabled, to prevent multiple builds from simultaneously trying to build or retrieve the same target files.

-s, --silent, --quiet
  Silent. Do not print commands that are executed to rebuild target files. Also suppresses SCons status messages.

-S, --no-keep-going, --stop
  Ignored for compatibility with GNU make.

--site-dir=dir
  Uses the named dir as the site dir rather than the default site_scons dir. This dir will get prepended to sys.path, the module dir/site_init.py will get loaded if it exists, and dir/site_tools will get added to the default toolpath.

--stack-size=KILOBYTES
  Set the size stack used to run threads to KILOBYTES. This value determines the stack size of the threads used to run jobs. These are the threads that execute the actions of the builders for the nodes that are out-of-date. Note that this option has no effect unless the num_jobs option, which corresponds to -j and --jobs, is larger than one. Using a stack size that is too small may cause stack overflow errors. This usually shows up as segmentation faults that cause scons to abort before building anything. Using a stack size that is too large will cause scons to use more memory than required and may slow down the entire build process.

  The default value is to use a stack size of 256 kilobytes, which should be appropriate for most uses. You should not need to increase this value unless you encounter stack overflow errors.

-t, --touch
  Ignored for compatibility with GNU make. (Touching a file to make it appear up-to-date is unnecessary when using scons.)

--taskmastertrace=file
  Prints trace information to the specified file about how the internal Taskmaster object evaluates and controls the order in which Nodes are built. A file name of - may be used to specify the standard output.

-tree=options
  Prints a tree of the dependencies after each top-level target is built. This prints out some or all of the tree, in various formats, depending on the options specified:

--tree=all
  Print the entire dependency tree after each top-level target is built. This prints out the complete dependency tree, including implicit dependencies and ignored dependencies.

--tree=derived
  Restricts the tree output to only derived (target) files, not source files.

--tree=status
  Prints status information for each displayed node.

--tree=prune
  Prunes the tree to avoid repeating dependency information for nodes that have already been displayed. Any node that has already been displayed will have its name printed in [square brackets], as an indication that the dependencies for that node can be found by searching for the relevant output higher up in the tree.

  Multiple options may be specified, separated by commas:

        # Prints only derived files, with status information:
        scons --tree=derived,status

        # Prints all dependencies of target, with status information
        # and pruning dependencies of already-visited Nodes:
        scons --tree=all,prune,status target

-u, --up, --search-up
  Walks up the directory structure until an SConstruct , Sconstruct or sconstruct file is found, and uses that as the top of the directory tree. If no targets are specified on the command line, only targets at or below the current directory will be built.

-U
  Works exactly the same way as the -u option except for the way default targets are handled. When this option is used and no targets are specified on the command line, all default targets that are defined in the SConscript(s) in the current directory are built, regardless of what directory the resultant targets end up in.

-v, --version
  Print the scons version, copyright information, list of authors, and any other relevant information. Then exit.

-w, --print-directory
  Print a message containing the working directory before and after other processing.

--no-print-directory
  Turn off -w, even if it was turned on implicitly.

--warn=type, --warn=no-type
  Enable or disable warnings. type specifies the type of warnings to be enabled or disabled:

--warn=all, --warn=no-all
  Enables or disables all warnings.

--warn=cache-write-error, --warn=no-cache-write-error
  Enables or disables warnings about errors trying to write a copy of a built file to a specified CacheDir(). These warnings are disabled by default.

--warn=corrupt-sconsign, --warn=no-corrupt-sconsign
  Enables or disables warnings about unfamiliar signature data in .sconsign files. These warnings are enabled by default.

--warn=dependency, --warn=no-dependency
  Enables or disables warnings about dependencies. These warnings are disabled by default.

--warn=deprecated, --warn=no-deprecated
  Enables or disables all warnings about use of deprecated features. These warnings are enabled by default. Warnings for some specific deprecated features may be enabled or disabled individually; see below.

  --warn=deprecated-copy, --warn=no-deprecated-copy Enables or disables warnings about use of the deprecated env.Copy() method.

  --warn=deprecated-source-signatures, --warn=no-deprecated-source-signatures Enables or disables warnings about use of the deprecated SourceSignatures() function or env.SourceSignatures() method.

  --warn=deprecated-target-signatures, --warn=no-deprecated-target-signatures Enables or disables warnings about use of the deprecated TargetSignatures() function or env.TargetSignatures() method.

--warn=duplicate-environment, --warn=no-duplicate-environment
  Enables or disables warnings about missing SConscript files.

--warn=misleading-keywords, --warn=no-misleading-keywords
  Enables or disables warnings about use of the misspelled keywords targets and sources when calling Builders. (Note the last s characters, the correct spellings are target and source.) These warnings are enabled by default.

--warn=missing-sconscript, --warn=no-missing-sconscript
  Enables or disables warnings about attempts to specify a build of a target with two different construction environments that use the same action. These warnings are enabled by default.

--warn=no-md5-module, --warn=no-no-md5-module
  Enables or disables warnings about the version of Python not having an MD5 checksum module available. These warnings are enabled by default.

--warn=no-metaclass-support, --warn=no-no-metaclass-support
  Enables or disables warnings about the version of Python not supporting metaclasses when the --debug=memoizer option is used. These warnings are enabled by default.

--warn=no-object-count, --warn=no-no-object-count
  Enables or disables warnings about the --debug=object feature not working when scons is run with the python -O option or from optimized Python (.pyo) modules.

--warn=no-parallel-support, --warn=no-no-parallel-support
  Enables or disables warnings about the version of Python not being able to support parallel builds when the -j option is used. These warnings are enabled by default.

--warn=python-version, --warn=no-python-version
  Enables or disables the warning about running SCons with a deprecated version of Python. These warnings are enabled by default.

--warn=reserved-variable, --warn=no-reserved-variable
  Enables or disables warnings about attempts to set the reserved construction variable names TARGET, TARGETS, SOURCE or SOURCES. These warnings are disabled by default.

--warn=stack-size, --warn=no-stack-size
  Enables or disables warnings about requests to set the stack size that could not be honored. These warnings are enabled by default.

-Y repository, --repository=repository, --srcdir=repository
  Search the specified repository for any input and target files not found in the local directory hierarchy. Multiple -Y options may be specified, in which case the repositories are searched in the order specified.

## CONFIGURATION FILE REFERENCE

### Construction Environments

A construction environment is the basic means by which the SConscript files communicate build information to scons. A new construction environment is created using the Environment function:

      env = Environment()

Variables, called construction variables, may be set in a construction environment either by specifyng them as keywords when the object is created or by assigning them a value after the object is created:

      env = Environment(FOO = 'foo')
      env['BAR'] = 'bar'

As a convenience, construction variables may also be set or modified by the parse_flags keyword argument, which applies the ParseFlags method (described below) to the argument value after all other processing is completed. This is useful either if the exact content of the flags is unknown (for example, read from a control file) or if the flags are distributed to a number of construction variables.

      env = Environment(parse_flags = '-Iinclude -DEBUG -lm')

This example adds 'include' to CPPPATH, 'EBUG' to CPPDEFINES, and 'm' to LIBS.

By default, a new construction environment is initialized with a set of builder methods and construction variables that are appropriate for the current platform. An optional platform keyword argument may be used to specify that an environment should be initialized for a different platform:

      env = Environment(platform = 'cygwin')
      env = Environment(platform = 'os2')
      env = Environment(platform = 'posix')
      env = Environment(platform = 'win32')

Specifying a platform initializes the appropriate construction variables in the environment to use and generate file names with prefixes and suffixes appropriate for the platform.

Note that the win32 platform adds the SYSTEMDRIVE and SYSTEMROOT variables from the user's external environment to the construction environment's ENV dictionary. This is so that any executed commands that use sockets to connect with other systems (such as fetching source files from external CVS repository specifications like :pserver:anonymous@cvs.sourceforge.net:/cvsroot/scons) will work on Windows systems.

The platform argument may be function or callable object, in which case the Environment() method will call the specified argument to update the new construction environment:

      def my_platform(env):
          env['VAR'] = 'xyzzy'

      env = Environment(platform = my_platform)

Additionally, a specific set of tools with which to initialize the environment may be specified as an optional keyword argument:

      env = Environment(tools = ['msvc', 'lex'])

Non-built-in tools may be specified using the toolpath argument:

      env = Environment(tools = ['default', 'foo'], toolpath = ['tools'])

This looks for a tool specification in tools/foo.py (as well as using the ordinary default tools for the platform). foo.py should have two functions: generate(env, **kw) and exists(env). The generate() function modifies the passed-in environment to set up variables so that the tool can be executed; it may use any keyword arguments that the user supplies (see below) to vary its initialization. The exists() function should return a true value if the tool is available. Tools in the toolpath are used before any of the built-in ones. For example, adding gcc.py to the toolpath would override the built-in gcc tool. Also note that the toolpath is stored in the environment for use by later calls to Clone() and Tool() methods:

      base = Environment(toolpath=['custom_path'])
      derived = base.Clone(tools=['custom_tool'])
      derived.CustomBuilder()

The elements of the tools list may also be functions or callable objects, in which case the Environment() method will call the specified elements to update the new construction environment:

      def my_tool(env):
          env['XYZZY'] = 'xyzzy'

      env = Environment(tools = [my_tool])

The individual elements of the tools list may also themselves be two-element lists of the form (toolname, kw_dict). SCons searches for the toolname specification file as described above, and passes kw_dict, which must be a dictionary, as keyword arguments to the tool's generate function. The generate function can use the arguments to modify the tool's behavior by setting up the environment in different ways or otherwise changing its initialization.

      # in tools/my_tool.py:
      def generate(env, **kw):
        # Sets MY_TOOL to the value of keyword argument 'arg1' or 1.
        env['MY_TOOL'] = kw.get('arg1', '1')
      def exists(env):
        return 1

      # in SConstruct:
      env = Environment(tools = ['default', ('my_tool', {'arg1': 'abc'})],
                        toolpath=['tools'])

The tool definition (i.e. my_tool()) can use the PLATFORM variable from the environment it receives to customize the tool for different platforms.

If no tool list is specified, then SCons will auto-detect the installed tools using the PATH variable in the ENV construction variable and the platform name when the Environment is constructed. Changing the PATH variable after the Environment is constructed will not cause the tools to be redetected.

SCons supports the following tool specifications out of the box:

      386asm
      aixc++
      aixcc
      aixf77
      aixlink
      ar
      as
      bcc32
      c++
      cc
      cvf
      dmd
      dvipdf
      dvips
      f77
      f90
      f95
      fortran
      g++
      g77
      gas
      gcc
      gfortran
      gnulink
      gs
      hpc++
      hpcc
      hplink
      icc
      icl
      ifl
      ifort
      ilink
      ilink32
      intelc
      jar
      javac
      javah
      latex
      lex
      link
      linkloc
      m4
      masm
      midl
      mingw
      mslib
      mslink
      msvc
      msvs
      mwcc
      mwld
      nasm
      pdflatex
      pdftex
      qt
      rmic
      rpcgen
      sgiar
      sgic++
      sgicc
      sgilink
      sunar
      sunc++
      suncc
      sunlink
      swig
      tar
      tex
      tlib
      yacc
      zip

Additionally, there is a "tool" named default which configures the environment with a default set of tools for the current platform.

On posix and cygwin platforms the GNU tools (e.g. gcc) are preferred by SCons, on Windows the Microsoft tools (e.g. msvc) followed by MinGW are preferred by SCons, and in OS/2 the IBM tools (e.g. icc) are preferred by SCons.

### Builder Methods

Build rules are specified by calling a construction environment's builder methods. The arguments to the builder methods are target (a list of targets to be built, usually file names) and source (a list of sources to be built, usually file names).

Because long lists of file names can lead to a lot of quoting, scons supplies a Split() global function and a same-named environment method that split a single string into a list, separated on strings of white-space characters. (These are similar to the string.split() method from the standard Python library, but work even if the input isn't a string.)

Like all Python arguments, the target and source arguments to a builder method can be specified either with or without the "target" and "source" keywords. When the keywords are omitted, the target is first, followed by the source. The following are equivalent examples of calling the Program builder method:

      env.Program('bar', ['bar.c', 'foo.c'])
      env.Program('bar', Split('bar.c foo.c'))
      env.Program('bar', env.Split('bar.c foo.c'))
      env.Program(source =  ['bar.c', 'foo.c'], target = 'bar')
      env.Program(target = 'bar', Split('bar.c foo.c'))
      env.Program(target = 'bar', env.Split('bar.c foo.c'))
      env.Program('bar', source = string.split('bar.c foo.c'))

Target and source file names that are not absolute path names (that is, do not begin with / on POSIX systems or \ on Windows systems, with or without an optional drive letter) are interpreted relative to the directory containing the SConscript file being read. An initial # (hash mark) on a path name means that the rest of the file name is interpreted relative to the directory containing the top-level SConstruct file, even if the # is followed by a directory separator character (slash or backslash).

Examples:

      # The comments describing the targets that will be built
      # assume these calls are in a SConscript file in the
      # a subdirectory named "subdir".

      # Builds the program "subdir/foo" from "subdir/foo.c":
      env.Program('foo', 'foo.c')

      # Builds the program "/tmp/bar" from "subdir/bar.c":
      env.Program('/tmp/bar', 'bar.c')

      # An initial '#' or '#/' are equivalent; the following
      # calls build the programs "foo" and "bar" (in the
      # top-level SConstruct directory) from "subdir/foo.c" and
      # "subdir/bar.c", respectively:
      env.Program('#foo', 'foo.c')
      env.Program('#/bar', 'bar.c')

      # Builds the program "other/foo" (relative to the top-level
      # SConstruct directory) from "subdir/foo.c":
      env.Program('#other/foo', 'foo.c')

When the target shares the same base name as the source and only the suffix varies, and if the builder method has a suffix defined for the target file type, then the target argument may be omitted completely, and scons will deduce the target file name from the source file name. The following examples all build the executable program bar (on POSIX systems) or bar.exe (on Windows systems) from the bar.c source file:

      env.Program(target = 'bar', source = 'bar.c')
      env.Program('bar', source = 'bar.c')
      env.Program(source = 'bar.c')
      env.Program('bar.c')

As a convenience, a srcdir keyword argument may be specified when calling a Builder. When specified, all source file strings that are not absolute paths will be interpreted relative to the specified srcdir. The following example will build the build/prog (or build/prog.exe on Windows) program from the files src/f1.c and src/f2.c:

      env.Program('build/prog', ['f1.c', 'f2.c'], srcdir='src')

It is possible to override or add construction variables when calling a builder method by passing additional keyword arguments. These overridden or added variables will only be in effect when building the target, so they will not affect other parts of the build. For example, if you want to add additional libraries for just one program:

      env.Program('hello', 'hello.c', LIBS=['gl', 'glut'])

or generate a shared library with a non-standard suffix:

      env.SharedLibrary('word', 'word.cpp',
                        SHLIBSUFFIX='.ocx',
                        LIBSUFFIXES=['.ocx'])

(Note that both the $SHLIBSUFFIX and $LIBSUFFIXES variables must be set if you want SCons to search automatically for dependencies on the non-standard library names; see the descriptions of these variables, below, for more information.)

It is also possible to use the parse_flags keyword argument in an override:

      env = Program('hello', 'hello.c', parse_flags = '-Iinclude -DEBUG -lm')

This example adds 'include' to CPPPATH, 'EBUG' to CPPDEFINES, and 'm' to LIBS.

Although the builder methods defined by scons are, in fact, methods of a construction environment object, they may also be called without an explicit environment:

      Program('hello', 'hello.c')
      SharedLibrary('word', 'word.cpp')

In this case, the methods are called internally using a default construction environment that consists of the tools and values that scons has determined are appropriate for the local system.

Builder methods that can be called without an explicit environment may be called from custom Python modules that you import into an SConscript file by adding the following to the Python module:

      from SCons.Script import *

All builder methods return a list-like object containing Nodes that represent the target or targets that will be built. A Node is an internal SCons object which represents build targets or sources.

The returned Node-list object can be passed to other builder methods as source(s) or passed to any SCons function or method where a filename would normally be accepted. For example, if it were necessary to add a specific -D flag when compiling one specific object file:

      bar_obj_list = env.StaticObject('bar.c', CPPDEFINES='-DBAR')
      env.Program(source = ['foo.c', bar_obj_list, 'main.c'])

Using a Node in this way makes for a more portable build by avoiding having to specify a platform-specific object suffix when calling the Program() builder method.

Note that Builder calls will automatically "flatten" the source and target file lists, so it's all right to have the bar_obj list return by the StaticObject() call in the middle of the source file list. If you need to manipulate a list of lists returned by Builders directly using Python, you can either build the list by hand:

      foo = Object('foo.c')
      bar = Object('bar.c')
      objects = ['begin.o'] + foo + ['middle.o'] + bar + ['end.o']
      for object in objects:
          print str(object)

Or you can use the Flatten() function supplied by scons to create a list containing just the Nodes, which may be more convenient:

      foo = Object('foo.c')
      bar = Object('bar.c')
      objects = Flatten(['begin.o', foo, 'middle.o', bar, 'end.o'])
      for object in objects:
          print str(object)

Note also that because Builder calls return a list-like object, not an actual Python list, you should not use the Python += operator to append Builder results to a Python list. Because the list and the object are different types, Python will not update the original list in place, but will instead create a new Node-list object containing the concatenation of the list elements and the Builder results. This will cause problems for any other Python variables in your SCons configuration that still hold on to a reference to the original list. Instead, use the Python .extend() method to make sure the list is updated in-place. Example:

      object_files = []

      # Do NOT use += as follows:
      #
      #    object_files += Object('bar.c')
      #
      # It will not update the object_files list in place.
      #
      # Instead, use the .extend() method:
      object_files.extend(Object('bar.c'))

The path name for a Node's file may be used by passing the Node to the Python-builtin str() function:

      bar_obj_list = env.StaticObject('bar.c', CPPDEFINES='-DBAR')
      print "The path to bar_obj is:", str(bar_obj_list[0])

Note again that because the Builder call returns a list, we have to access the first element in the list (bar_obj_list[0]) to get at the Node that actually represents the object file.

Builder calls support a chdir keyword argument that specifies that the Builder's action(s) should be executed after changing directory. If the chdir argument is a string or a directory Node, scons will change to the specified directory. If the chdir is not a string or Node and is non-zero, then scons will change to the target file's directory.

      # scons will change to the "sub" subdirectory
      # before executing the "cp" command.
      env.Command('sub/dir/foo.out', 'sub/dir/foo.in',
                  "cp dir/foo.in dir/foo.out",
                  chdir='sub')

      # Because chdir is not a string, scons will change to the
      # target's directory ("sub/dir") before executing the
      # "cp" command.
      env.Command('sub/dir/foo.out', 'sub/dir/foo.in',
                  "cp foo.in foo.out",
                  chdir=1)

Note that scons will not automatically modify its expansion of construction variables like $TARGET and $SOURCE when using the chdir keyword argument--that is, the expanded file names will still be relative to the top-level SConstruct directory, and consequently incorrect relative to the chdir directory. If you use the chdir keyword argument, you will typically need to supply a different command line using expansions like ${TARGET.file} and ${SOURCE.file} to use just the filename portion of the targets and source.

scons provides the following builder methods:

CFile()
env.CFile()
  Builds a C source file given a lex (.l) or yacc (.y) input file. The suffix specified by the $CFILESUFFIX construction variable (.c by default) is automatically added to the target if it is not already present. Example:

        # builds foo.c
        env.CFile(target = 'foo.c', source = 'foo.l')
        # builds bar.c
        env.CFile(target = 'bar', source = 'bar.y')

CXXFile()
env.CXXFile()
  Builds a C++ source file given a lex (.ll) or yacc (.yy) input file. The suffix specified by the $CXXFILESUFFIX construction variable (.cc by default) is automatically added to the target if it is not already present. Example:

        # builds foo.cc
        env.CXXFile(target = 'foo.cc', source = 'foo.ll')
        # builds bar.cc
        env.CXXFile(target = 'bar', source = 'bar.yy')

DVI()
env.DVI()
  Builds a .dvi file from a .tex, .ltx or .latex input file. If the source file suffix is .tex, scons will examine the contents of the file; if the string \documentclass or \documentstyle is found, the file is assumed to be a LaTeX file and the target is built by invoking the $LATEXCOM command line; otherwise, the $TEXCOM command line is used. If the file is a LaTeX file, the DVI() builder method will also examine the contents of the .aux file and invoke the $BIBTEX command line if the string bibdata is found, start $MAKEINDEX to generate an index if a .ind file is found and will examine the contents .log file and re-run the $LATEXCOM command if the log file says it is necessary.

  The suffix .dvi (hard-coded within TeX itself) is automatically added to the target if it is not already present. Examples:

        # builds from aaa.tex
        env.DVI(target = 'aaa.dvi', source = 'aaa.tex')
        # builds bbb.dvi
        env.DVI(target = 'bbb', source = 'bbb.ltx')
        # builds from ccc.latex
        env.DVI(target = 'ccc.dvi', source = 'ccc.latex')

Install()
env.Install()
  Installs one or more source files or directories in the specified target, which must be a directory. The names of the specified source files or directories remain the same within the destination directory.

        env.Install('/usr/local/bin', source = ['foo', 'bar'])

InstallAs()
env.InstallAs()
  Installs one or more source files or directories to specific names, allowing changing a file or directory name as part of the installation. It is an error if the target and source arguments list different numbers of files or directories.

        env.InstallAs(target = '/usr/local/bin/foo',
                      source = 'foo_debug')
        env.InstallAs(target = ['../lib/libfoo.a', '../lib/libbar.a'],
                      source = ['libFOO.a', 'libBAR.a'])

Jar()
env.Jar()
  Builds a Java archive (.jar) file from the specified list of sources. Any directories in the source list will be searched for .class files). Any .java files in the source list will be compiled to .class files by calling the Java() Builder.

  If the $JARCHDIR value is set, the jar command will change to the specified directory using the -C option. If $JARCHDIR is not set explicitly, &SCons; will use the top of any subdirectory tree in which Java .class were built by the Java() Builder.

  If the contents any of the source files begin with the string Manifest-Version, the file is assumed to be a manifest and is passed to the jar command with the m option set.

        env.Jar(target = 'foo.jar', source = 'classes')

        env.Jar(target = 'bar.jar',
                source = ['bar1.java', 'bar2.java'])

Java()
env.Java()
  Builds one or more Java class files. The sources may be any combination of explicit .java files, or directory trees which will be scanned for .java files.

  SCons will parse each source .java file to find the classes (including inner classes) defined within that file, and from that figure out the target .class files that will be created. The class files will be placed underneath the specified target directory.

  SCons will also search each Java file for the Java package name, which it assumes can be found on a line beginning with the string package in the first column; the resulting .class files will be placed in a directory reflecting the specified package name. For example, the file Foo.java defining a single public Foo class and containing a package name of sub.dir will generate a corresponding sub/dir/Foo.class class file.

  Example:

        env.Java(target = 'classes', source = 'src')
        env.Java(target = 'classes', source = ['src1', 'src2'])
        env.Java(target = 'classes', source = ['File1.java', 'File2.java'])

JavaH()
env.JavaH()
  Builds C header and source files for implementing Java native methods. The target can be either a directory in which the header files will be written, or a header file name which will contain all of the definitions. The source can be the names of .class files, the names of .java files to be compiled into .class files by calling the Java() builder method, or the objects returned from the Java() builder method.

  If the construction variable $JAVACLASSDIR is set, either in the environment or in the call to the JavaH() builder method itself, then the value of the variable will be stripped from the beginning of any .class file names.

  Examples:

        # builds java_native.h
        classes = env.Java(target = 'classdir', source = 'src')
        env.JavaH(target = 'java_native.h', source = classes)

        # builds include/package_foo.h and include/package_bar.h
        env.JavaH(target = 'include',
                  source = ['package/foo.class', 'package/bar.class'])

        # builds export/foo.h and export/bar.h
        env.JavaH(target = 'export',
                  source = ['classes/foo.class', 'classes/bar.class'],
                  JAVACLASSDIR = 'classes')

Library()
env.Library()
  A synonym for the StaticLibrary() builder method.

LoadableModule()
env.LoadableModule()
  On most systems, this is the same as SharedLibrary(). On Mac OS X (Darwin) platforms, this creates a loadable module bundle.

M4()
env.M4()
  Builds an output file from an M4 input file. This uses a default $M4FLAGS value of -E, which considers all warnings to be fatal and stops on the first warning when using the GNU version of m4. Example:

        env.M4(target = 'foo.c', source = 'foo.c.m4')

Moc()
env.Moc()
  Builds an output file from a moc input file. Moc input files are either header files or cxx files. This builder is only available after using the tool 'qt'. See the $QTDIR variable for more information. Example:

        env.Moc('foo.h') # generates moc_foo.cc
        env.Moc('foo.cpp') # generates foo.moc

MSVSProject()
env.MSVSProject()
  Builds a Microsoft Visual Studio project file, and by default builds a solution file as well.

  This builds a Visual Studio project file, based on the version of Visual Studio that is configured (either the latest installed version, or the version specified by $MSVS_VERSION in the Environment constructor). For Visual Studio 6, it will generate a .dsp file. For Visual Studio 7 (.NET) and later versions, it will generate a .vcproj file.

  By default, this also generates a solution file for the specified project, a .dsw file for Visual Studio 6 or a .sln file for Visual Studio 7 (.NET). This behavior may be disabled by specifying auto_build_solution=0 when you call MSVSProject(), in which case you presumably want to build the solution file(s) by calling the MSVSSolution() Builder (see below).

  It takes several lists of filenames to be placed into the project file. These are currently limited to srcs, incs, localincs, resources, and misc. These are pretty self-explanatory, but it should be noted that these lists are added to the $SOURCES construction variable as strings, NOT as SCons File Nodes. This is because they represent file names to be added to the project file, not the source files used to build the project file.

  The above filename lists are all optional, although at least one must be specified for the resulting project file to be non-empty.

  In addition to the above lists of values, the following values may be specified:

  target: The name of the target .dsp or .vcproj file. The correct suffix for the version of Visual Studio must be used, but the $MSVSPROJECTSUFFIX construction variable will be defined to the correct value (see example below).

  variant: The name of this particular variant. For Visual Studio 7 projects, this can also be a list of variant names. These are typically things like "Debug" or "Release", but really can be anything you want. For Visual Studio 7 projects, they may also specify a target platform separated from the variant name by a | (vertical pipe) character: Debug|Xbox. The default target platform is Win32. Multiple calls to MSVSProject() with different variants are allowed; all variants will be added to the project file with their appropriate build targets and sources.

  buildtarget: An optional string, node, or list of strings or nodes (one per build variant), to tell the Visual Studio debugger what output target to use in what build variant. The number of buildtarget entries must match the number of variant entries.

  runfile: The name of the file that Visual Studio 7 and later will run and debug. This appears as the value of the Output field in the resutling Visual Studio project file. If this is not specified, the default is the same as the specified buildtarget value.

  Example usage:

        barsrcs = ['bar.cpp'],
        barincs = ['bar.h'],
        barlocalincs = ['StdAfx.h']
        barresources = ['bar.rc','resource.h']
        barmisc = ['bar_readme.txt']

        dll = env.SharedLibrary(target = 'bar.dll',
                                source = barsrcs)

        env.MSVSProject(target = 'Bar' + env['MSVSPROJECTSUFFIX'],
                        srcs = barsrcs,
                        incs = barincs,
                        localincs = barlocalincs,
                        resources = barresources,
                        misc = barmisc,
                        buildtarget = dll,
                        variant = 'Release')

MSVSSolution()
env.MSVSSolution()
  Builds a Microsoft Visual Studio solution file.

  This builds a Visual Studio solution file, based on the version of Visual Studio that is configured (either the latest installed version, or the version specified by $MSVS_VERSION in the construction environment). For Visual Studio 6, it will generate a .dsw file. For Visual Studio 7 (.NET), it will generate a .sln file.

  The following values must be specified:

  target: The name of the target .dsw or .sln file. The correct suffix for the version of Visual Studio must be used, but the value $MSVSSOLUTIONSUFFIX will be defined to the correct value (see example below).

  variant: The name of this particular variant, or a list of variant names (the latter is only supported for MSVS 7 solutions). These are typically things like "Debug" or "Release", but really can be anything you want. For MSVS 7 they may also specify target platform, like this "Debug|Xbox". Default platform is Win32.

  projects: A list of project file names, or Project nodes returned by calls to the MSVSProject() Builder, to be placed into the solution file. It should be noted that these file names are NOT added to the $SOURCES environment variable in form of files, but rather as strings. This is because they represent file names to be added to the solution file, not the source files used to build the solution file.

  (NOTE: Currently only one project is supported per solution.)

  Example Usage:

        env.MSVSSolution(target = 'Bar' + env['MSVSSOLUTIONSUFFIX'],
                         projects = ['bar' + env['MSVSPROJECTSUFFIX']],
                         variant = 'Release')

Object()
env.Object()
  A synonym for the StaticObject() builder method.

Package()
env.Package()
  Builds software distribution packages. Packages consist of files to install and packaging information. The former may be specified with the &source; parameter and may be left out, in which case the &FindInstalledFiles; function will collect all files that have an Install()orInstallAs()Builderattached.Ifthe&target;,is not specified it will be deduced from additional information given to this Builder.

  The packaging information is specified with the help of construction variables documented below. This information is called a tag to stress that some of them can also be attached to files with the &Tag; function. The mandatory ones will complain if they were not specified. They vary depending on chosen target packager.

  The target packager may be selected with the "PACKAGETYPE" command line option or with the $PACKAGETYPE construction variable. Currently the following packagers available:

  * msi - Microsoft Installer
  * rpm - Redhat Package Manger
  * ipkg - Itsy Package Management System
  * tarbz2 - compressed tar
  * targz - compressed tar
  * zip - zip file
  * src_tarbz2 - compressed tar source
  * src_targz - compressed tar source
  * src_zip - zip file source

  An updated list is always available under the "package_type" option when running "scons --help" on a project that has packaging activated.

        env = Environment(tools=['default', 'packaging'])
        env.Install('/bin/', 'my_program')
        env.Package( NAME           = 'foo',
                     VERSION        = '1.2.3',
                     PACKAGEVERSION = 0,
                     PACKAGETYPE    = 'rpm',
                     LICENSE        = 'gpl',
                     SUMMARY        = 'balalalalal',
                     DESCRIPTION    = 'this should be really really long',
                     X_RPM_GROUP    = 'Application/fu',
                     SOURCE_URL     = 'http://foo.org/foo-1.2.3.tar.gz'
                )

PCH()
env.PCH()
  Builds a Microsoft Visual C++ precompiled header. Calling this builder method returns a list of two targets: the PCH as the first element, and the object file as the second element. Normally the object file is ignored. This builder method is only provided when Microsoft Visual C++ is being used as the compiler. The PCH builder method is generally used in conjuction with the PCH construction variable to force object files to use the precompiled header:

        env['PCH'] = env.PCH('StdAfx.cpp')[0]

PDF()
env.PDF()
  Builds a .pdf file from a .dvi input file (or, by extension, a .tex, .ltx, or .latex input file). The suffix specified by the $PDFSUFFIX construction variable (.pdf by default) is added automatically to the target if it is not already present. Example:

        # builds from aaa.tex
        env.PDF(target = 'aaa.pdf', source = 'aaa.tex')
        # builds bbb.pdf from bbb.dvi
        env.PDF(target = 'bbb', source = 'bbb.dvi')

PostScript()
env.PostScript()
  Builds a .ps file from a .dvi input file (or, by extension, a .tex, .ltx, or .latex input file). The suffix specified by the $PSSUFFIX construction variable (.ps by default) is added automatically to the target if it is not already present. Example:

        # builds from aaa.tex
        env.PostScript(target = 'aaa.ps', source = 'aaa.tex')
        # builds bbb.ps from bbb.dvi
        env.PostScript(target = 'bbb', source = 'bbb.dvi')

Program()
env.Program()
  Builds an executable given one or more object files or C, C++, D, or Fortran source files. If any C, C++, D or Fortran source files are specified, then they will be automatically compiled to object files using the Object() builder method; see that builder method's description for a list of legal source file suffixes and how they are interpreted. The target executable file prefix (specified by the $PROGPREFIX construction variable; nothing by default) and suffix (specified by the $PROGSUFFIX construction variable; by default, .exe on Windows systems, nothing on POSIX systems) are automatically added to the target if not already present. Example:

        env.Program(target = 'foo', source = ['foo.o', 'bar.c', 'baz.f'])

RES()
env.RES()
  Builds a Microsoft Visual C++ resource file. This builder method is only provided when Microsoft Visual C++ or MinGW is being used as the compiler. The .res (or .o for MinGW) suffix is added to the target name if no other suffix is given. The source file is scanned for implicit dependencies as though it were a C file. Example:

        env.RES('resource.rc')

RMIC()
env.RMIC()
  Builds stub and skeleton class files for remote objects from Java .class files. The target is a directory relative to which the stub and skeleton class files will be written. The source can be the names of .class files, or the objects return from the Java() builder method.

  If the construction variable $JAVACLASSDIR is set, either in the environment or in the call to the RMIC() builder method itself, then the value of the variable will be stripped from the beginning of any .class file names.

        classes = env.Java(target = 'classdir', source = 'src')
        env.RMIC(target = 'outdir1', source = classes)

        env.RMIC(target = 'outdir2',
                 source = ['package/foo.class', 'package/bar.class'])

        env.RMIC(target = 'outdir3',
                 source = ['classes/foo.class', 'classes/bar.class'],
                 JAVACLASSDIR = 'classes')

RPCGenClient()
env.RPCGenClient()
  Generates an RPC client stub (_clnt.c) file from a specified RPC (.x) source file. Because rpcgen only builds output files in the local directory, the command will be executed in the source file's directory by default.

        # Builds src/rpcif_clnt.c
        env.RPCGenClient('src/rpcif.x')

RPCGenHeader()
env.RPCGenHeader()
  Generates an RPC header (.h) file from a specified RPC (.x) source file. Because rpcgen only builds output files in the local directory, the command will be executed in the source file's directory by default.

        # Builds src/rpcif.h
        env.RPCGenHeader('src/rpcif.x')

RPCGenService()
env.RPCGenService()
  Generates an RPC server-skeleton (_svc.c) file from a specified RPC (.x) source file. Because rpcgen only builds output files in the local directory, the command will be executed in the source file's directory by default.

        # Builds src/rpcif_svc.c
        env.RPCGenClient('src/rpcif.x')

RPCGenXDR()
env.RPCGenXDR()
  Generates an RPC XDR routine (_xdr.c) file from a specified RPC (.x) source file. Because rpcgen only builds output files in the local directory, the command will be executed in the source file's directory by default.

        # Builds src/rpcif_xdr.c
        env.RPCGenClient('src/rpcif.x')

SharedLibrary()
env.SharedLibrary()
  Builds a shared library (.so on a POSIX system, .dll on Windows) given one or more object files or C, C++, D or Fortran source files. If any source files are given, then they will be automatically compiled to object files. The static library prefix and suffix (if any) are automatically added to the target. The target library file prefix (specified by the $SHLIBPREFIX construction variable; by default, lib on POSIX systems, nothing on Windows systems) and suffix (specified by the $SHLIBSUFFIX construction variable; by default, .dll on Windows systems, .so on POSIX systems) are automatically added to the target if not already present. Example:

        env.SharedLibrary(target = 'bar', source = ['bar.c', 'foo.o'])

  On Windows systems, the SharedLibrary() builder method will always build an import (.lib) library in addition to the shared (.dll) library, adding a .lib library with the same basename if there is not already a .lib file explicitly listed in the targets.

  Any object files listed in the source must have been built for a shared library (that is, using the SharedObject() builder method). scons will raise an error if there is any mismatch.

  On Windows systems, specifying register=1 will cause the .dll to be registered after it is built using REGSVR32. The command that is run ("regsvr32" by default) is determined by $REGSVR construction variable, and the flags passed are determined by $REGSVRFLAGS. By default, $REGSVRFLAGS includes the /s option, to prevent dialogs from popping up and requiring user attention when it is run. If you change $REGSVRFLAGS, be sure to include the /s option. For example,

        env.SharedLibrary(target = 'bar',
                          source = ['bar.cxx', 'foo.obj'],
                          register=1)

  will register bar.dll as a COM object when it is done linking it.

SharedObject()
env.SharedObject()
  Builds an object file for inclusion in a shared library. Source files must have one of the same set of extensions specified above for the StaticObject() builder method. On some platforms building a shared object requires additional compiler option (e.g. -fPIC for gcc) in addition to those needed to build a normal (static) object, but on some platforms there is no difference between a shared object and a normal (static) one. When there is a difference, SCons will only allow shared objects to be linked into a shared library, and will use a different suffix for shared objects. On platforms where there is no difference, SCons will allow both normal (static) and shared objects to be linked into a shared library, and will use the same suffix for shared and normal (static) objects. The target object file prefix (specified by the $SHOBJPREFIX construction variable; by default, the same as $OBJPREFIX) and suffix (specified by the $SHOBJSUFFIX construction variable) are automatically added to the target if not already present. Examples:

        env.SharedObject(target = 'ddd', source = 'ddd.c')
        env.SharedObject(target = 'eee.o', source = 'eee.cpp')
        env.SharedObject(target = 'fff.obj', source = 'fff.for')

  Note that the source files will be scanned according to the suffix mappings in the SourceFileScanner object. See the section "Scanner Objects," below, for a more information.

StaticLibrary()
env.StaticLibrary()
  Builds a static library given one or more object files or C, C++, D or Fortran source files. If any source files are given, then they will be automatically compiled to object files. The static library prefix and suffix (if any) are automatically added to the target. The target library file prefix (specified by the $LIBPREFIX construction variable; by default, lib on POSIX systems, nothing on Windows systems) and suffix (specified by the $LIBSUFFIX construction variable; by default, .lib on Windows systems, .a on POSIX systems) are automatically added to the target if not already present. Example:

        env.StaticLibrary(target = 'bar', source = ['bar.c', 'foo.o'])

  Any object files listed in the source must have been built for a static library (that is, using the StaticObject() builder method). scons will raise an error if there is any mismatch.

StaticObject()
env.StaticObject()
  Builds a static object file from one or more C, C++, D, or Fortran source files. Source files must have one of the following extensions:

          .asm    assembly language file
          .ASM    assembly language file
          .c      C file
          .C      Windows:  C file
                  POSIX:  C++ file
          .cc     C++ file
          .cpp    C++ file
          .cxx    C++ file
          .cxx    C++ file
          .c++    C++ file
          .C++    C++ file
          .d      D file
          .f      Fortran file
          .F      Windows:  Fortran file
                  POSIX:  Fortran file + C pre-processor
          .for    Fortran file
          .FOR    Fortran file
          .fpp    Fortran file + C pre-processor
          .FPP    Fortran file + C pre-processor
          .m      Object C file
          .mm     Object C++ file
          .s      assembly language file
          .S      Windows:  assembly language file
                  POSIX:  assembly language file + C pre-processor
          .spp    assembly language file + C pre-processor
          .SPP    assembly language file + C pre-processor

  The target object file prefix (specified by the $OBJPREFIX construction variable; nothing by default) and suffix (specified by the $OBJSUFFIX construction variable; .obj on Windows systems, .o on POSIX systems) are automatically added to the target if not already present. Examples:

        env.StaticObject(target = 'aaa', source = 'aaa.c')
        env.StaticObject(target = 'bbb.o', source = 'bbb.c++')
        env.StaticObject(target = 'ccc.obj', source = 'ccc.f')

  Note that the source files will be scanned according to the suffix mappings in SourceFileScanner object. See the section "Scanner Objects," below, for a more information.

Tar()
env.Tar()
  Builds a tar archive of the specified files and/or directories. Unlike most builder methods, the Tar() builder method may be called multiple times for a given target; each additional call adds to the list of entries that will be built into the archive. Any source directories will be scanned for changes to any on-disk files, regardless of whether or not scons knows about them from other Builder or function calls.

        env.Tar('src.tar', 'src')

        # Create the stuff.tar file.
        env.Tar('stuff', ['subdir1', 'subdir2'])
        # Also add "another" to the stuff.tar file.
        env.Tar('stuff', 'another')

        # Set TARFLAGS to create a gzip-filtered archive.
        env = Environment(TARFLAGS = '-c -z')
        env.Tar('foo.tar.gz', 'foo')

        # Also set the suffix to .tgz.
        env = Environment(TARFLAGS = '-c -z',
                          TARSUFFIX = '.tgz')
        env.Tar('foo')

TypeLibrary()
env.TypeLibrary()
  Builds a Windows type library (.tlb) file from an input IDL file (.idl). In addition, it will build the associated inteface stub and proxy source files, naming them according to the base name of the .idl file. For example,

        env.TypeLibrary(source="foo.idl")

  Will create foo.tlb, foo.h, foo_i.c, foo_p.c and foo_data.c files.

Uic()
env.Uic()
  Builds a header file, an implementation file and a moc file from an ui file. and returns the corresponding nodes in the above order. This builder is only available after using the tool 'qt'. Note: you can specify .ui files directly as source files to the Program(), Library()andSharedLibrary()builders without using this builder. Using this builder lets you override the standard naming conventions (be careful: prefixes are always prepended to names of built files; if you don't want prefixes, you may set them to ``). See the $QTDIR variable for more information. Example:

        env.Uic('foo.ui') # -> ['foo.h', 'uic_foo.cc', 'moc_foo.cc']
        env.Uic(target = Split('include/foo.h gen/uicfoo.cc gen/mocfoo.cc'),
                source = 'foo.ui') # -> ['include/foo.h', 'gen/uicfoo.cc', 'gen/mocfoo.cc']

Zip()
env.Zip()
  Builds a zip archive of the specified files and/or directories. Unlike most builder methods, the Zip() builder method may be called multiple times for a given target; each additional call adds to the list of entries that will be built into the archive. Any source directories will be scanned for changes to any on-disk files, regardless of whether or not scons knows about them from other Builder or function calls.

        env.Zip('src.zip', 'src')

        # Create the stuff.zip file.
        env.Zip('stuff', ['subdir1', 'subdir2'])
        # Also add "another" to the stuff.tar file.
        env.Zip('stuff', 'another')

  All targets of builder methods automatically depend on their sources. An explicit dependency can be specified using the Depends method of a construction environment (see below).

  In addition, scons automatically scans source files for various programming languages, so the dependencies do not need to be specified explicitly. By default, SCons can C source files, C++ source files, Fortran source files with .F (POSIX systems only), .fpp, or .FPP file extensions, and assembly language files with .S (POSIX systems only), .spp, or .SPP files extensions for C preprocessor dependencies. SCons also has default support for scanning D source files, You can also write your own Scanners to add support for additional source file types. These can be added to the default Scanner object used by the Object() StaticObject() and SharedObject() Builders by adding them to the SourceFileScanner object as follows:

  See the section "Scanner Objects," below, for a more information about defining your own Scanner objects.

### Methods and Functions to Do Things

In addition to Builder methods, scons provides a number of other construction environment methods and global functions to manipulate the build configuration.

Usually, a construction environment method and global function with the same name both exist so that you don't have to remember whether to a specific bit of functionality must be called with or without a construction environment. In the following list, if you call something as a global function it looks like:

      Function(arguments)

and if you call something through a construction environment it looks like:

      env.Function(arguments)

If you can call the functionality in both ways, then both forms are listed.

Global functions may be called from custom Python modules that you import into an SConscript file by adding the following to the Python module:

      from SCons.Script import *

Except where otherwise noted, the same-named construction environment method and global function provide the exact same functionality. The only difference is that, where appropriate, calling the functionality through a construction environment will substitute construction variables into any supplied strings. For example:

      env = Environment(FOO = 'foo')
      Default('$FOO')
      env.Default('$FOO')

In the above example, the first call to the global Default() function will actually add a target named $FOO to the list of default targets, while the second call to the env.Default() construction environment method will expand the value and add a target named foo to the list of default targets. For more on construction variable expansion, see the next section on construction variables.

Construction environment methods and global functions supported by scons include:

Action(action, [strfunction, varlist])
env.Action(action, [strfunction, varlist])
  Creates an Action object for the specified action. See the section "Action Objects," below, for a complete explanation of the arguments and behavior.

  Note that the env.Action() form of the invocation will expand construction variables in any arguments strings, including the action argument, at the time it is called using the construction variables in the env construction environment through which env.Action() was called. The Action() form delays all variable expansion until the Action object is actually used.

AddMethod(object,function, [name])
env.AddMethod(function, [name])
  When called with the AddMethod() form, adds the specified function to the specified object as the specified method name. When called with the env.AddMethod() form, adds the specified function to the construction environment env as the specified method name. In both cases, if name is omitted or None, the name of the specified function itself is used for the method name.

  Examples:

        # Note that the first argument to the function to
        # be attached as a method must be the object through
        # which the method will be called; the Python
        # convention is to call it 'self'.
        def my_method(self, arg):
            print "my_method() got", arg

        # Use the global AddMethod() function to add a method
        # to the Environment class.  This
        AddMethod(Environment, my_method)
        env = Environment()
        env.my_method('arg')

        # Add the function as a method, using the function
        # name for the method call.
        env = Environment()
        env.AddMethod(my_method, 'other_method_name')
        env.other_method_name('another arg')

AddOption(arguments)
  This function adds a new command-line option to be recognized. The specified arguments are the same as supported by the standard Python optparse.add_option() method (with a few additional capabilities noted below); see the documentation for optparse for a thorough discussion of its option-processing capabities. (Note that although the optparse module was not a standard module until Python 2.3, scons contains a compatible version of the module that is used to provide identical functionality when run by earlier Python versions.)

  In addition to the arguments and values supported by the optparse.add_option () method, the SCons AddOption() function allows you to set the nargs keyword value to '?' (a string with just the question mark) to indicate that the specified long option(s) take(s) an optional argument. When nargs = '?' is passed to the AddOption() function, the const keyword argument may be used to supply the "default" value that should be used when the option is specified on the command line without an explicit argument.

  If no default= keyword argument is supplied when calling AddOption(), the option will have a default value of None.

  Once a new command-line option has been added with AddOption(), the option value may be accessed using GetOption() or env.GetOption(). The value may also be set, using SetOption() or env.SetOption(), if conditions in a SConscript require overriding any default value. Note, however, that a value specified on the command line will always override a value set by any SConscript file.

  Any specified help= strings for the new option(s) will be displayed by the -H or -h options (the latter only if no other help text is specified in the SConscript files). The help text for the local options specified by AddOption() will appear below the SCons options themselves, under a separate Local Options heading. The options will appear in the help text in the order in which the AddOption() calls occur.

  Example:

        AddOption('--prefix',
                  dest='prefix',
                  nargs=1, type='string',
                  action='store',
                  metavar='DIR',
                  help='installation prefix')
        env = Environment(PREFIX = GetOption('prefix'))

AddPostAction(target, action)
env.AddPostAction(target, action)
  Arranges for the specified action to be performed after the specified target has been built. The specified action(s) may be an Action object, or anything that can be converted into an Action object (see below).

AddPreAction(target, action)
env.AddPreAction(target, action)
  Arranges for the specified action to be performed before the specified target is built. The specified action(s) may be an Action object, or anything that can be converted into an Action object (see below).

Alias(alias, [targets, [action]])
env.Alias(alias, [targets, [action]])
  Creates one or more phony targets that expand to one or more other targets. An optional action (command) or list of actions can be specified that will be executed whenever the any of the alias targets are out-of-date. Returns the Node object representing the alias, which exists outside of any file system. This Node object, or the alias name, may be used as a dependency of any other target, including another alias. Alias can be called multiple times for the same alias to add additional targets to the alias, or additional actions to the list for this alias.

  Examples:

        Alias('install')
        Alias('install', '/usr/bin')
        Alias(['install', 'install-lib'], '/usr/local/lib')

        env.Alias('install', ['/usr/local/bin', '/usr/local/lib'])
        env.Alias('install', ['/usr/local/man'])

        env.Alias('update', ['file1', 'file2'], "update_database $SOURCES")

AllowSubstExceptions([exception, ...])
  Specifies the exceptions that will be allowed when expanding construction variables. By default, any construction variable expansions that generate a NameError or IndexError exception will expand to a '' (a null string) and not cause scons to fail. All exceptions not in the specified list will generate an error message and terminate processing.

  If AllowSubstExceptions is called multiple times, each call completely overwrites the previous list of allowed exceptions.

  Example:

        # Requires that all construction variable names exist.
        # (You may wish to do this if you want to enforce strictly
        # that all construction variables must be defined before use.)
        AllowSubstExceptions()

        # Also allow a string containing a zero-division expansion
        # like '${1 / 0}' to evalute to ''.
        AllowSubstExceptions(IndexError, NameError, ZeroDivisionError)

AlwaysBuild(target, ...)
env.AlwaysBuild(target, ...)
  Marks each given target so that it is always assumed to be out of date, and will always be rebuilt if needed. Note, however, that AlwaysBuild() does not add its target(s) to the default target list, so the targets will only be built if they are specified on the command line, or are a dependent of a target specified on the command line--but they will always be built if so specified. Multiple targets can be passed in to a single call to AlwaysBuild().

env.Append(key=val, [...])
  Appends the specified keyword arguments to the end of construction variables in the environment. If the Environment does not have the specified construction variable, it is simply added to the environment. If the values of the construction variable and the keyword argument are the same type, then the two values will be simply added together. Otherwise, the construction variable and the value of the keyword argument are both coerced to lists, and the lists are added together. (See also the Prepend method, below.)

  Example:

        env.Append(CCFLAGS = ' -g', FOO = ['foo.yyy'])

env.AppendENVPath(name, newpath, [envname, sep])
  This appends new path elements to the given path in the specified external environment (ENV by default). This will only add any particular path once (leaving the last one it encounters and ignoring the rest, to preserve path order), and to help assure this, will normalize all paths (using os.path.normpath and os.path.normcase). This can also handle the case where the given old path variable is a list instead of a string, in which case a list will be returned instead of a string.

  Example:

        print 'before:',env['ENV']['INCLUDE']
        include_path = '/foo/bar:/foo'
        env.AppendENVPath('INCLUDE', include_path)
        print 'after:',env['ENV']['INCLUDE']

        yields:
        before: /foo:/biz
        after: /biz:/foo/bar:/foo

env.AppendUnique(key=val, [...])
  Appends the specified keyword arguments to the end of construction variables in the environment. If the Environment does not have the specified construction variable, it is simply added to the environment. If the construction variable being appended to is a list, then any value(s) that already exist in the construction variable will not be added again to the list.

  Example:

        env.AppendUnique(CCFLAGS = '-g', FOO = ['foo.yyy'])

env.BitKeeper()
  A factory function that returns a Builder object to be used to fetch source files using BitKeeper. The returned Builder is intended to be passed to the SourceCode function.

  Example:

        env.SourceCode('.', env.BitKeeper())

BuildDir(build_dir, src_dir, [duplicate])
env.BuildDir(build_dir, src_dir, [duplicate])
  Synonyms for VariantDir() and env.VariantDir(). The build_dir argument bedomes the variant_dir argument of VariantDir() or env.VariantDir(). (This will be officially deprecated some day.)

Builder(action, [arguments])
env.Builder(action, [arguments])
  Creates a Builder object for the specified action. See the section "Builder Objects," below, for a complete explanation of the arguments and behavior.

  Note that the env.Builder() form of the invocation will expand construction variables in any arguments strings, including the action argument, at the time it is called using the construction variables in the env construction environment through which env.Builder() was called. The Builder() form delays all variable expansion until after the Builder object is actually called.

CacheDir(cache_dir)
env.CacheDir(cache_dir)
  Specifies that scons will maintain a cache of derived files in cache_dir . The derived files in the cache will be shared among all the builds using the same CacheDir() call. Specifying a cache_dir of None disables derived file caching.

  Calling env.CacheDir() will only affect targets built through the specified construction environment. Calling CacheDir() sets a global default that will be used by all targets built through construction environments that do not have an env.CacheDir() specified.

  When a CacheDir() is being used and scons finds a derived file that needs to be rebuilt, it will first look in the cache to see if a derived file has already been built from identical input files and an identical build action (as incorporated into the MD5 build signature). If so, scons will retrieve the file from the cache. If the derived file is not present in the cache, scons will rebuild it and then place a copy of the built file in the cache (identified by its MD5 build signature), so that it may be retrieved by other builds that need to build the same derived file from identical inputs.

  Use of a specified CacheDir() may be disabled for any invocation by using the --cache-disable option.

  If the --cache-force option is used, scons will place a copy of all derived files in the cache, even if they already existed and were not built by this invocation. This is useful to populate a cache the first time CacheDir() is added to a build, or after using the --cache-disable option.

  When using CacheDir(), scons will report, "Retrieved `file' from cache," unless the --cache-show option is being used. When the --cache-show option is used, scons will print the action that would have been used to build the file, without any indication that the file was actually retrieved from the cache. This is useful to generate build logs that are equivalent regardless of whether a given derived file has been built in-place or retrieved from the cache.

  The NoCache() method can be used to disable caching of specific files. This can be useful if inputs and/or outputs of some tool are impossible to predict or prohibitively large.

Clean(targets, files_or_dirs)
env.Clean(targets, files_or_dirs)
  This specifies a list of files or directories which should be removed whenever the targets are specified with the -c command line option. The specified targets may be a list or an individual target. Multiple calls to Clean() are legal, and create new targets or add files and directories to the clean list for the specified targets.

  Multiple files or directories should be specified either as separate arguments to the Clean() method, or as a list. Clean() will also accept the return value of any of the construction environment Builder methods. Examples:

  The related NoClean() function overrides calling Clean() for the same target, and any targets passed to both functions will not be removed by the -c option.

  Examples:

        Clean('foo', ['bar', 'baz'])
        Clean('dist', env.Program('hello', 'hello.c'))
        Clean(['foo', 'bar'], 'something_else_to_clean')

Command(target, source, action, [key=val, ...])
env.Command(target, source, action, [key=val, ...])
  Executes a specific action (or list of actions) to build a target file or files. This is more convenient than defining a separate Builder object for a single special-case build.

  As a special case, the source_scanner keyword argument can be used to specify a Scanner object that will be used to scan the sources. (The global DirScanner object can be used if any of the sources will be directories that must be scanned on-disk for changes to files that aren't already specified in other Builder of function calls.)

  Any other keyword arguments specified override any same-named existing construction variables.

  An action can be an external command, specified as a string, or a callable Python object; see "Action Objects," below, for more complete information. Also note that a string specifying an external command may be preceded by an @ (at-sign) to suppress printing the command in question, or by a - (hyphen) to ignore the exit status of the external command.

  Examples:

        env.Command('foo.out', 'foo.in',
                    "$FOO_BUILD < $SOURCES > $TARGET")

        env.Command('bar.out', 'bar.in',
                    ["rm -f $TARGET",
                     "$BAR_BUILD < $SOURCES > $TARGET"],
                    ENV = {'PATH' : '/usr/local/bin/'})

        def rename(env, target, source):
            import os
            os.rename('.tmp', str(target[0]))

        env.Command('baz.out', 'baz.in',
                    ["$BAZ_BUILD < $SOURCES > .tmp",
                     rename ])

  Note that the Command() function will usually assume, by default, that the specified targets and/or sources are Files, if no other part of the configuration identifies what type of entry it is. If necessary, you can explicitly specify that targets or source nodes should be treated as directoriese by using the Dir() or env.Dir() functions.

  Examples:

        env.Command('ddd.list', Dir('ddd'), 'ls -l $SOURCE > $TARGET')

        env['DISTDIR'] = 'destination/directory'
        env.Command(env.Dir('$DISTDIR')), None, make_distdir)

  (Also note that SCons will usually automatically create any directory necessary to hold a target file, so you normally don't need to create directories by hand.)

Configure(env, [custom_tests, conf_dir, log_file, config_h])
env.Configure([custom_tests, conf_dir, log_file, config_h])
  Creates a Configure object for integrated functionality similar to GNU autoconf. See the section "Configure Contexts," below, for a complete explanation of the arguments and behavior.

env.Clone([key=val, ...])
  Return a separate copy of a construction environment. If there are any keyword arguments specified, they are added to the returned copy, overwriting any existing values for the keywords.

  Example:

        env2 = env.Clone()
        env3 = env.Clone(CCFLAGS = '-g')

  Additionally, a list of tools and a toolpath may be specified, as in the Environment constructor:

        def MyTool(env): env['FOO'] = 'bar'
        env4 = env.Clone(tools = ['msvc', MyTool])

  The parse_flags keyword argument is also recognized:

        # create an environment for compiling programs that use wxWidgets
        wx_env = env.Clone(parse_flags = '!wx-config --cflags --cxxflags')

env.Copy([key=val, ...])
  A now-deprecated synonym for env.Clone().

env.CVS(repository, module)
  A factory function that returns a Builder object to be used to fetch source files from the specified CVS repository. The returned Builder is intended to be passed to the SourceCode function.

  The optional specified module will be added to the beginning of all repository path names; this can be used, in essence, to strip initial directory names from the repository path names, so that you only have to replicate part of the repository directory hierarchy in your local build directory.

  Examples:

        # Will fetch foo/bar/src.c
        # from /usr/local/CVSROOT/foo/bar/src.c.
        env.SourceCode('.', env.CVS('/usr/local/CVSROOT'))

        # Will fetch bar/src.c
        # from /usr/local/CVSROOT/foo/bar/src.c.
        env.SourceCode('.', env.CVS('/usr/local/CVSROOT', 'foo'))

        # Will fetch src.c
        # from /usr/local/CVSROOT/foo/bar/src.c.
        env.SourceCode('.', env.CVS('/usr/local/CVSROOT', 'foo/bar'))

Decider(function)
env.Decider(function)
  Specifies that all up-to-date decisions for targets built through this construction environment will be handled by the specified function. The function can be one of the following strings that specify the type of decision function to be performed:

    timestamp-newer
      Specifies that a target shall be considered out of date and rebuilt if the dependency's timestamp is newer than the target file's timestamp. This is the behavior of the classic Make utility, and make can be used a synonym for timestamp-newer.

    timestamp-match
      Specifies that a target shall be considered out of date and rebuilt if the dependency's timestamp is different than the timestamp recorded the last time the target was built. This provides behavior very similar to the classic Make utility (in particular, files are not opened up so that their contents can be checksummed) except that the target will also be rebuilt if a dependency file has been restored to a version with an earlier timestamp, such as can happen when restoring files from backup archives.

    MD5
      Specifies that a target shall be considered out of date and rebuilt if the dependency's content has changed sine the last time the target was built, as determined be performing an MD5 checksum on the dependency's contents and comparing it to the checksum recorded the last time the target was built. content can be used as a synonym for MD5.

    MD5-timestamp
      Specifies that a target shall be considered out of date and rebuilt if the dependency's content has changed sine the last time the target was built, except that dependencies with a timestamp that matches the last time the target was rebuilt will be assumed to be up-to-date and not rebuilt. This provides behavior very similar to the MD5 behavior of always checksumming file contents, with an optimization of not checking the contents of files whose timestamps haven't changed. The drawback is that SCons will not detect if a file's content has changed but its timestamp is the same, as might happen in an automated script that runs a build, updates a file, and runs the build again, all within a single second.

  Examples:

        # Use exact timestamp matches by default.
        Decider('timestamp-match')

        # Use MD5 content signatures for any targets built
        # with the attached construction environment.
        env.Decider('content')

  In addition to the above already-available functions, the function argument may be an actual Python function that takes the following three arguments:

    dependency
      The Node (file) which should cause the target to be rebuilt if it has "changed" since the last tme target was built.

    target
      The Node (file) being built. In the normal case, this is what should get rebuilt if the dependency has "changed."

    prev_ni
      Stored information about the state of the dependency the last time the target was built. This can be consulted to match various file characteristics such as the timestamp, size, or content signature.

  The function should return a True (non-zero) value if the dependency has "changed" since the last time the target was built (indicating that the target should be rebuilt), and False (zero) otherwise (indicating that the target should not be rebuilt). Note that the decision can be made using whatever criteria are appopriate. Ignoring some or all of the function arguments is perfectly normal.

  Example:

        def my_decider(dependency, target, prev_ni):
            return not os.path.exists(str(target))

        env.Decider(my_decider)

Default(targets)
env.Default(targets)
  This specifies a list of default targets, which will be built by scons if no explicit targets are given on the command line. Multiple calls to Default() are legal, and add to the list of default targets.

  Multiple targets should be specified as separate arguments to the Default() method, or as a list. Default() will also accept the Node returned by any of a construction environment's builder methods.

  Examples:

        Default('foo', 'bar', 'baz')
        env.Default(['a', 'b', 'c'])
        hello = env.Program('hello', 'hello.c')
        env.Default(hello)

  An argument to Default() of None will clear all default targets. Later calls to Default() will add to the (now empty) default-target list like normal.

  The current list of targets added using the Default() function or method is available in the DEFAULT_TARGETS list; see below.

DefaultEnvironment([args])
  Creates and returns a default construction environment object. This construction environment is used internally by SCons in order to execute many of the global functions in this list, and to fetch source files transparently from source code management systems.

Depends(target, dependency)
env.Depends(target, dependency)
  Specifies an explicit dependency; the target file(s) will be rebuilt whenever the dependency file(s) has changed. This should only be necessary for cases where the dependency is not caught by a Scanner for the file.

  Example:

        env.Depends('foo', 'other-input-file-for-foo')

env.Dictionary([vars])
  Returns a dictionary object containing copies of all of the construction variables in the environment. If there are any variable names specified, only the specified construction variables are returned in the dictionary.

  Example:

        dict = env.Dictionary()
        cc_dict = env.Dictionary('CC', 'CCFLAGS', 'CCCOM')

Dir(name, [directory])
env.Dir(name, [directory])
  This returns a Directory Node, an object that represents the specified directory name. name can be a relative or absolute path. directory is an optional directory that will be used as the parent directory. If no directory is specified, the current script's directory is used as the parent.

  If name is a list, SCons returns a list of Dir nodes. Construction variables are expanded in name.

  Directory Nodes can be used anywhere you would supply a string as a directory name to a Builder method or function. Directory Nodes have attributes and methods that are useful in many situations; see "File and Directory Nodes," below.

env.Dump([key])
  Returns a pretty printable representation of the environment. key, if not None, should be a string containing the name of the variable of interest.

  This SConstruct:

        env=Environment()
        print env.Dump('CCCOM')

  will print:

        env=Environment()
        print env.Dump()

  will print:

        { 'AR': 'ar',
          'ARCOM': '$AR $ARFLAGS $TARGET $SOURCESRANLIB $RANLIBFLAGS $TARGET',
          'ARFLAGS': ['r'],
          'AS': 'as',
          'ASCOM': '$AS $ASFLAGS -o $TARGET $SOURCES',
          'ASFLAGS': [],
          ...

EnsurePythonVersion(major, minor)
env.EnsurePythonVersion(major, minor)
  Ensure that the Python version is at least major.minor. This function will print out an error message and exit SCons with a non-zero exit code if the actual Python version is not late enough.

  Example:

        EnsurePythonVersion(2,2)

EnsureSConsVersion(major, minor, [revision])
env.EnsureSConsVersion(major, minor, [revision])
  Ensure that the SCons version is at least major.minor, or major.minor.revision. if revision is specified. This function will print out an error message and exit SCons with a non-zero exit code if the actual SCons version is not late enough.

  Examples:

        EnsureSConsVersion(0,14)

        EnsureSConsVersion(0,96,90)

Environment([key=value, ...])
env.Environment([key=value, ...])
  Return a new construction environment initialized with the specified key=value pairs.

Execute(action, [strfunction, varlist])
env.Execute(action, [strfunction, varlist])
  Executes an Action object. The specified action may be an Action object (see the section "Action Objects," below, for a complete explanation of the arguments and behavior), or it may be a command-line string, list of commands, or executable Python function, each of which will be converted into an Action object and then executed. The exit value of the command or return value of the Python function will be returned.

Exit([value])
env.Exit([value])
  This tells scons to exit immediately with the specified value. A default exit value of 0 (zero) is used if no value is specified.

Export(vars)
env.Export(vars)
  This tells scons to export a list of variables from the current SConscript file to all other SConscript files. The exported variables are kept in a global collection, so subsequent calls to Export() will over-write previous exports that have the same name. Multiple variable names can be passed to Export() as separate arguments or as a list. A dictionary can be used to map variables to a different name when exported. Both local variables and global variables can be exported.

  Examples:

        env = Environment()
        # Make env available for all SConscript files to Import().
        Export("env")

        package = 'my_name'
        # Make env and package available for all SConscript files:.
        Export("env", "package")

        # Make env and package available for all SConscript files:
        Export(["env", "package"])

        # Make env available using the name debug:.
        Export({"debug":env})

  Note that the SConscript() function supports an exports argument that makes it easier to to export a variable or set of variables to a single SConscript file. See the description of the SConscript() function, below.

File(name, [directory])
env.File(name, [directory])
  This returns a File Node, an object that represents the specified file name. name can be a relative or absolute path. directory is an optional directory that will be used as the parent directory.

  If name is a list, SCons returns a list of File nodes. Construction variables are expanded in name.

  File Nodes can be used anywhere you would supply a string as a file name to a Builder method or function. File Nodes have attributes and methods that are useful in many situations; see "File and Directory Nodes," below.

FindFile(file, dirs)
env.FindFile(file, dirs)
  Search for file in the path specified by dirs. file may be a list of file names or a single file name. In addition to searching for files that exist in the filesytem, this function also searches for derived files that have not yet been built.

  Example:

        foo = env.FindFile('foo', ['dir1', 'dir2'])

FindInstalledFiles()
env.FindInstalledFiles()
  Returns the list of targets set up by the Install() or InstallAs() builders.

  This function serves as a convenient method to select the contents of a binary package.

  Example:

        Install( '/bin', [ 'executable_a', 'executable_b' ] )

        # will return the file node list
        # [ '/bin/executable_a', '/bin/executable_b' ]
        FindInstalledFiles()

        Install( '/lib', [ 'some_library' ] )

        # will return the file node list
        # [ '/bin/executable_a', '/bin/executable_b', '/lib/some_library' ]
        FindInstalledFiles()

FindSourceFiles(node='.')
env.FindSourceFiles(node='.')

  Returns the list of nodes which serve as the source of the built files. It does so by inspecting the dependency tree starting at the optional argument node which defaults to the '"."'-node. It will then return all leaves of node. These are all children which have no further children.

  This function is a convenient method to select the contents of a Source Package.

  Example:

        Program( 'src/main_a.c' )
        Program( 'src/main_b.c' )
        Program( 'main_c.c' )

        # returns ['main_c.c', 'src/main_a.c', 'SConstruct', 'src/main_b.c']
        FindSourceFiles()

        # returns ['src/main_b.c', 'src/main_a.c' ]
        FindSourceFiles( 'src' )

  As you can see build support files (SConstruct in the above example) will also be returned by this function.

FindPathDirs(variable)
  Returns a function (actually a callable Python object) intended to be used as the path_function of a Scanner object. The returned object will look up the specified variable in a construction environment and treat the construction variable's value as a list of directory paths that should be searched (like CPPPATH, LIBPATH, etc.).

  Note that use of FindPathDirs() is generally preferable to writing your own path_function for the following reasons: 1) The returned list will contain all appropriate directories found in source trees (when VariantDir() is used) or in code repositories (when Repository() or the -Y option are used). 2) scons will identify expansions of variable that evaluate to the same list of directories as, in fact, the same list, and avoid re-scanning the directories for files, when possible.

  Example:

        def my_scan(node, env, path, arg):
            # Code to scan file contents goes here...
            return include_files

        scanner = Scanner(name = 'myscanner',
                          function = my_scan,
                          path_function = FindPathDirs('MYPATH'))

Flatten(sequence)
env.Flatten(sequence)
  Takes a sequence (that is, a Python list or tuple) that may contain nested sequences and returns a flattened list containing all of the individual elements in any sequence. This can be helpful for collecting the lists returned by calls to Builders; other Builders will automatically flatten lists specified as input, but direct Python manipulation of these lists does not.

  Examples:

        foo = Object('foo.c')
        bar = Object('bar.c')

        # Because `foo' and `bar' are lists returned by the Object() Builder,
        # `objects' will be a list containing nested lists:
        objects = ['f1.o', foo, 'f2.o', bar, 'f3.o']

        # Passing such a list to another Builder is all right because
        # the Builder will flatten the list automatically:
        Program(source = objects)

        # If you need to manipulate the list directly using Python, you need to
        # call Flatten() yourself, or otherwise handle nested lists:
        for object in Flatten(objects):
            print str(object)

GetBuildFailures()
  Returns a list of exceptions for the actions that failed while attempting to build targets. Each element in the returned list is a BuildError object with the following attributes that record various aspects of the build failure:

  .node The node that was being built when the build failure occurred.

  .status The numeric exit status returned by the command or Python function that failed when trying to build the specified Node.

  .errstr The SCons error string describing the build failure. (This is often a generic message like "Error 2" to indicate that an executed command exited with a status of 2.)

  .filename The name of the file or directory that actually caused the failure. This may be different from the .node attribute. For example, if an attempt to build a target named sub/dir/target fails because the sub/dir directory could not be created, then the .node attribute will be sub/dir/target but the .filename attribute will be sub/dir.

  .executor The SCons Executor object for the target Node being built. This can be used to retrieve the construction environment used for the failed action.

  .action The actual SCons Action object that failed. This will be one specific action out of the possible list of actions that would have been executed to build the target.

  .command The actual expanded command that was executed and failed, after expansion of $TARGET, $SOURCE, and other construction variables.

  Note that the GetBuildFailures() function will always return an empty list until any build failure has occurred, which means that GetBuildFailures() will always return an empty list while the SConscript files are being read. Its primary intended use is for functions that will be executed before SCons exits by passing them to the standard Python atexit.register() function. Example:

        import atexit

        def print_build_failures():
            from SCons.Script import GetBuildFailures
            for bf in GetBuildFailures():
                print "%s failed: %s" % (bf.node, bf.errstr)

        atexit.register(print_build_failures)

GetBuildPath(file, [...])
env.GetBuildPath(file, [...])
  Returns the scons path name (or names) for the specified file (or files). The specified file or files may be scons Nodes or strings representing path names.

GetLaunchDir()
env.GetLaunchDir()
  Returns the absolute path name of the directory from which scons was initially invoked. This can be useful when using the -u, -U or -D options, which internally change to the directory in which the SConstruct file is found.

GetOption(name)
env.GetOption(name)
  This function provides a way to query the value of SCons options set on scons command line (or set using the SetOption() function). The options supported are:

    cache_debug
    which corresponds to --cache_debug;
    cache_disable
      which corresponds to --cache_disable;
    cache_force
      which corresponds to --cache_force;
    cache_show
      which corresponds to --cache_show;
    clean
      which corresponds to -c, --clean and --remove;
    config
      which corresponds to --config;
    directory
      which corresponds to -C and --directory;
    diskcheck
      which corresponds to --diskcheck
    duplicate
      which corresponds to --duplicate;
    file
      which corresponds to -f, --file, --makefile and --sconstruct;
    help
      which corresponds to -h and --help;
    ignore_errors
      which corresponds to --ignore-errors;
    implicit_cache
      which corresponds to --implicit-cache;
    implicit_deps_changed
      which corresponds to --implicit-deps-changed;
    implicit_deps_unchanged
      which corresponds to --implicit-deps-unchanged;
    interactive
      which corresponds to --interact and --interactive;
    keep_going
      which corresponds to -k and --keep-going;
    max_drift
      which corresponds to --max-drift;
    no_exec
      which corresponds to -n, --no-exec, --just-print, --dry-run and --recon;
    no_site_dir
      which corresponds to --no-site-dir;
    num_jobs
      which corresponds to -j and --jobs;
    profile_file
      which corresponds to --profile;
    question
      which corresponds to -q and --question;
    random
      which corresponds to --random;
    repository
      which corresponds to -Y, --repository and --srcdir;
    silent
      which corresponds to -s, --silent and --quiet;
    site_dir
      which corresponds to --site-dir;
    stack_size
      which corresponds to --stack-size;
    taskmastertrace_file
      which corresponds to --taskmastertrace; and
    warn
      which corresponds to --warn and --warning.

  See the documentation for the corresponding command line object for information about each specific option.

Glob(pattern, [ondisk, source, strings])
env.Glob(pattern, [ondisk, source, strings])
  Returns Nodes (or strings) that match the specified pattern, relative to the directory of the current SConscript file. The env.Glob() form performs string substition on pattern and returns whatever matches the resulting expanded pattern.

  The specified pattern uses Unix shell style metacharacters for matching:

          *       matches everything
          ?       matches any single character
          [seq]   matches any character in seq
          [!seq]  matches any char not in seq

  Character matches do not span directory separators.

  The Glob() knows about repositories (see the Repository() function) and source directories (see the VariantDir() function) and returns a Node (or string, if so configured) in the local (SConscript) directory if matching Node is found anywhere in a corresponding repository or source directory.

  The ondisk argument may be set to False (or any other non-true value) to disable the search for matches on disk, thereby only returning matches among already-configured File or Dir Nodes. The default behavior is to return corresponding Nodes for any on-disk matches found.

  The source argument may be set to True (or any equivalent value) to specify that, when the local directory is a VariantDir(), the returned Nodes should be from the corresponding source directory, not the local directory.

  The strings argument may be set to True (or any equivalent value) to have the Glob() function return strings, not Nodes, that represent the matched files or directories. The returned strings will be relative to the local (SConscript) directory. (Note that This may make it easier to perform arbitrary manipulation of file names, but if the returned strings are passed to a different SConscript file, any Node translation will be relative to the other SConscript directory, not the original SConscript directory.)

  Example:

        Program('foo', Glob('*.c'))

Help(text)
env.Help(text)
  This specifies help text to be printed if the -h argument is given to scons. If Help is called multiple times, the text is appended together in the order that Help is called.

Ignore(target, dependency)
env.Ignore(target, dependency)
  The specified dependency file(s) will be ignored when deciding if the target file(s) need to be rebuilt.

  Examples:

        env.Ignore('foo', 'foo.c')
        env.Ignore('bar', ['bar1.h', 'bar2.h'])

Import(vars)
env.Import(vars)
  This tells scons to import a list of variables into the current SConscript file. This will import variables that were exported with Export() or in the exports argument to SConscript(). Variables exported by SConscript() have precedence. Multiple variable names can be passed to Import() as separate arguments or as a list. The variable "*" can be used to import all variables.

  Examples:

        Import("env")
        Import("env", "variable")
        Import(["env", "variable"])
        Import("*")

Literal(string)
env.Literal(string)
  The specified string will be preserved as-is and not have construction variables expanded.

Local(targets)
env.Local(targets)
  The specified targets will have copies made in the local tree, even if an already up-to-date copy exists in a repository. Returns a list of the target Node or Nodes.

env.MergeFlags(arg, [unique])
  Merges the specified arg values to the construction envrionment's construction variables. If the arg argument is not a dictionary, it is converted to one by calling env.ParseFlags() on the argument before the values are merged. Note that arg must be a single value, so multiple strings must be passed in as a list, not as separate arguments to env.MergeFlags().

  By default, duplicate values are eliminated; you can, however, specify unique=0 to allow duplicate values to be added. When eliminating duplicate values, any construction variables that end with the string PATH keep the left-most unique value. All other construction variables keep the right-most unique value.

  Examples:

        # Add an optimization flag to $CCFLAGS.
        env.MergeFlags('-O3')

        # Combine the flags returned from running pkg-config with an optimization
        # flag and merge the result into the construction variables.
        env.MergeFlags(['!pkg-config gtk+-2.0 --cflags', '-O3'])

        # Combine an optimization flag with the flags returned from running pkg-config
        # twice and merge the result into the construction variables.
        env.MergeFlags(['-O3',
                       '!pkg-config gtk+-2.0 --cflags --libs',
                       '!pkg-config libpng12 --cflags --libs'])

NoCache(target, ...)
env.NoCache(target, ...)
  Specifies a list of files which should not be cached whenever the CacheDir() method has been activated. The specified targets may be a list or an individual target.

  Multiple files should be specified either as separate arguments to the NoCache() method, or as a list. NoCache() will also accept the return value of any of the construction environment Builder methods.

  Calling NoCache() on directories and other non-File Node types has no effect because only File Nodes are cached.

  Examples:

        NoCache('foo.elf')
        NoCache(env.Program('hello', 'hello.c'))

NoClean(target, ...)
env.NoClean(target, ...)
  Specifies a list of files or directories which should not be removed whenever the targets (or their dependencies) are specified with the -c command line option. The specified targets may be a list or an individual target. Multiple calls to NoClean() are legal, and prevent each specified target from being removed by calls to the -c option.

  Multiple files or directories should be specified either as separate arguments to the NoClean() method, or as a list. NoClean() will also accept the return value of any of the construction environment Builder methods.

  Calling NoClean() for a target overrides calling Clean() for the same target, and any targets passed to both functions will not be removed by the -c option.

  Examples:

        NoClean('foo.elf')
        NoClean(env.Program('hello', 'hello.c'))

env.ParseConfig(command, [function, unique])
  Calls the specified function to modify the environment as specified by the output of command . The default function is env.MergeFlags(), which expects the output of a typical *-config command (for example, gtk-config) and adds the options to the appropriate construction variables. By default, duplicate values are not added to any construction variables; you can specify unique=0 to allow duplicate values to be added.

  Interpreted options and the construction variables they affect are as specified for the env.ParseFlags() method (which thie method calls). See that method's description, below, for a table of options and construction variables.

ParseDepends(filename, [must_exist, only_one])
env.ParseDepends(filename, [must_exist, only_one])
  Parses the contents of the specified filename as a list of dependencies in the style of Make or mkdep, and explicitly establishes all of the listed dependencies.

  By default, it is not an error if the specified filename does not exist. The optional must_exist argument may be set to a non-zero value to have scons throw an exception and generate an error if the file does not exist, or is otherwise inaccessible.

  The optional only_one argument may be set to a non-zero value to have scons thrown an exception and generate an error if the file contains dependency information for more than one target. This can provide a small sanity check for files intended to be generated by, for example, the gcc -M flag, which should typically only write dependency information for one output file into a corresponding .d file.

  The filename and all of the files listed therein will be interpreted relative to the directory of the SConscript file which calls the ParseDepends function.

env.ParseFlags(flags, ...)
  Parses one or more strings containing typical command-line flags for GCC tool chains and returns a dictionary with the flag values separated into the appropriate SCons construction variables. This is intended as a companion to the env.MergeFlags() method, but allows for the values in the returned dictionary to be modified, if necessary, before merging them into the construction environment. (Note that env.MergeFlags() will call this method if its argument is not a dictionary, so it is usually not necessary to call env.ParseFlags() directly unless you want to manipulate the values.)

  If the first character in any string is an exclamation mark (!), the rest of the string is executed as a command, and the output from the command is parsed as GCC tool chain command-line flags and added to the resulting dictionary.

  Flag values are translated accordig to the prefix found, and added to the following construction variables:

        -arch               CCFLAGS, LINKFLAGS
        -D                  CPPDEFINES
        -framework          FRAMEWORKS
        -frameworkdir=      FRAMEWORKPATH
        -include            CCFLAGS
        -isysroot           CCFLAGS, LINKFLAGS
        -I                  CPPPATH
        -l                  LIBS
        -L                  LIBPATH
        -mno-cygwin         CCFLAGS, LINKFLAGS
        -mwindows           LINKFLAGS
        -pthread            CCFLAGS, LINKFLAGS
        -std=               CFLAGS
        -Wa,                ASFLAGS, CCFLAGS
        -Wl,-rpath=         RPATH
        -Wl,-R,             RPATH
        -Wl,-R              RPATH
        -Wl,                LINKFLAGS
        -Wp,                CPPFLAGS
        -                   CCFLAGS
        +                   CCFLAGS, LINKFLAGS

  Any other strings not associated with options are assumed to be the names of libraries and added to the LIBS construction variable.

  Examples (all of which produce the same result):

        dict = env.ParseFlags('-O2 -Dfoo -Dbar=1')
        dict = env.ParseFlags('-O2', '-Dfoo', '-Dbar=1')
        dict = env.ParseFlags(['-O2', '-Dfoo -Dbar=1'])
        dict = env.ParseFlags('-O2', '!echo -Dfoo -Dbar=1')

env.Perforce()
  A factory function that returns a Builder object to be used to fetch source files from the Perforce source code management system. The returned Builder is intended to be passed to the SourceCode function.

  Example:

        env.SourceCode('.', env.Perforce())

  Perforce uses a number of external environment variables for its operation. Consequently, this function adds the following variables from the user's external environment to the construction environment's ENV dictionary: P4CHARSET, P4CLIENT, P4LANGUAGE, P4PASSWD, P4PORT, P4USER, SYSTEMROOT, USER, and USERNAME.

Platform(string)
  Returns a callable object that can be used to initialize a construction environment using the platform keyword of the Environment() method.

  Example:

        env = Environment(platform = Platform('win32'))

env.Platform(string)
  Applies the callable object for the specified platform string to the environment through which the method was called.

        env.Platform('posix')

  Note that the win32 platform adds the SYSTEMDRIVE and SYSTEMROOT variables from the user's external environment to the construction environment's ENV dictionary. This is so that any executed commands that use sockets to connect with other systems (such as fetching source files from external CVS repository specifications like :pserver:anonymous@cvs.sourceforge.net:/cvsroot/scons) will work on Windows systems.

Progress(callable, [interval])
Progress(string, [interval, file, overwrite])
Progress(list_of_strings, [interval, file, overwrite])
  Allows SCons to show progress made during the build by displaying a string or calling a function while evaluating Nodes (e.g. files).

  If the first specified argument is a Python callable (a function or an object that has a __call__() method), the function will be called once every interval times a Node is evaluated. The callable will be passed the evaluated Node as its only argument. (For future compatibility, it's a good idea to also add *args and **kw as arguments to your function or method. This will prevent the code from breaking if SCons ever changes the interface to call the function with additional arguments in the future.)

  An example of a simple custom progress function that prints a string containing the Node name every 10 Nodes:

        def my_progress_function(node, *args, **kw):
            print 'Evaluating node %s!' % node
        Progress(my_progress_function, interval=10)

  A more complicated example of a custom progress display object that prints a string containing a count every 100 evaluated Nodes. Note the use of \\r (a carriage return) at the end so that the string will overwrite itself on a display:

        import sys
        class ProgressCounter:
            count = 0
            def __call__(self, node, *args, **kw):
                self.count += 100
                sys.stderr.write('Evaluated %s nodes\r' % self.count)
        Progress(ProgressCounter(), interval=100)

  If the first argument Progress() is a string, the string will be displayed every interval evaluated Nodes. The default is to print the string on standard output; an alternate output stream may be specified with the file= argument. The following will print a series of dots on the error output, one dot for every 100 evaluated Nodes:

        import sys
        Progress('.', interval=100, file=sys.stderr)

  If the string contains the verbatim substring $TARGET, it will be replaced with the Node. Note that, for performance reasons, this is not a regular SCons variable substition, so you can not use other variables or use curly braces. The following example will print the name of every evaluated Node, using a \\r (carriage return) to cause each line to overwritten by the next line, and the overwrite= keyword argument to make sure the previously-printed file name is overwritten with blank spaces:

        import sys
        Progress('$TARGET\r', overwrite=True)

  If the first argument to Progress() is a list of strings, then each string in the list will be displayed in rotating fashion every interval evaluated Nodes. This can be used to implement a "spinner" on the user's screen as follows:

        Progress(['-\r', '\\\r', '|\r', '/\r'], interval=5)

Precious(target, ...)
env.Precious(target, ...)
  Marks each given target as precious so it is not deleted before it is rebuilt. Normally scons deletes a target before building it. Multiple targets can be passed in to a single call to Precious().

env.Prepend(key=val, [...])
  Appends the specified keyword arguments to the beginning of construction variables in the environment. If the Environment does not have the specified construction variable, it is simply added to the environment. If the values of the construction variable and the keyword argument are the same type, then the two values will be simply added together. Otherwise, the construction variable and the value of the keyword argument are both coerced to lists, and the lists are added together. (See also the Append method, above.)

  Example:

        env.Prepend(CCFLAGS = '-g ', FOO = ['foo.yyy'])

env.PrependENVPath(name, newpath, [envname, sep])
  This appends new path elements to the given path in the specified external environment (ENV by default). This will only add any particular path once (leaving the first one it encounters and ignoring the rest, to preserve path order), and to help assure this, will normalize all paths (using os.path.normpath and os.path.normcase). This can also handle the case where the given old path variable is a list instead of a string, in which case a list will be returned instead of a string.

  Example:

        print 'before:',env['ENV']['INCLUDE']
        include_path = '/foo/bar:/foo'
        env.PrependENVPath('INCLUDE', include_path)
        print 'after:',env['ENV']['INCLUDE']

  The above exmaple will print:

        before: /biz:/foo
        after: /foo/bar:/foo:/biz

env.PrependUnique(key=val, [...])
  Appends the specified keyword arguments to the beginning of construction variables in the environment. If the Environment does not have the specified construction variable, it is simply added to the environment. If the construction variable being appended to is a list, then any value(s) that already exist in the construction variable will not be added again to the list.

  Example:

        env.PrependUnique(CCFLAGS = '-g', FOO = ['foo.yyy'])

env.RCS()
  A factory function that returns a Builder object to be used to fetch source files from RCS. The returned Builder is intended to be passed to the SourceCode function:

  Examples:

        env.SourceCode('.', env.RCS())

  Note that scons will fetch source files from RCS subdirectories automatically, so configuring RCS as demonstrated in the above example should only be necessary if you are fetching from RCS,v files in the same directory as the source files, or if you need to explicitly specify RCS for a specific subdirectory.

env.Replace(key=val, [...])
  Replaces construction variables in the Environment with the specified keyword arguments.

  Example:

        env.Replace(CCFLAGS = '-g', FOO = 'foo.xxx')

Repository(directory)
env.Repository(directory)
  Specifies that directory is a repository to be searched for files. Multiple calls to Repository() are legal, and each one adds to the list of repositories that will be searched.

  To scons, a repository is a copy of the source tree, from the top-level directory on down, which may contain both source files and derived files that can be used to build targets in the local source tree. The canonical example would be an official source tree maintained by an integrator. If the repository contains derived files, then the derived files should have been built using scons, so that the repository contains the necessary signature information to allow scons to figure out when it is appropriate to use the repository copy of a derived file, instead of building one locally.

  Note that if an up-to-date derived file already exists in a repository, scons will not make a copy in the local directory tree. In order to guarantee that a local copy will be made, use the Local() method.

Requires(target, prerequisite)
env.Requires(target, prerequisite)
  Specifies an order-only relationship between the specified target file(s) and the specified prerequisite file(s). The prerequisite file(s) will be (re)built, if necessary, before the target file(s), but the target file(s) do not actually depend on the prerequisites and will not be rebuilt simply because the prerequisite file(s) change.

  Example:

        env.Requires('foo', 'file-that-must-be-built-before-foo')

Return([vars... , stop=])
  By default, this stops processing the current SConscript file and returns to the calling SConscript file the values of the variables named in the vars string arguments. Multiple strings contaning variable names may be passed to Return(). Any strings that contain white space

  The optional stop= keyword argument may be set to a false value to continue processing the rest of the SConscript file after the Return() call. This was the default behavior prior to SCons 0.98. However, the values returned are still the values of the variables in the named vars at the point Return() is called.

  Examples:

        # Returns without returning a value.
        Return()

        # Returns the value of the 'foo' Python variable.
        Return("foo")

        # Returns the values of the Python variables 'foo' and 'bar'.
        Return("foo", "bar")

        # Returns the values of Python variables 'val1' and 'val2'.
        Return('val1 val2')

Scanner(function, [argument, keys, path_function, node_class, node_factory, scan_check, recursive])
env.Scanner(function, [argument, keys, path_function, node_class, node_factory, scan_check, recursive])
  Creates a Scanner object for the specified function. See the section "Scanner Objects," below, for a complete explanation of the arguments and behavior.

env.SCCS()
  A factory function that returns a Builder object to be used to fetch source files from SCCS. The returned Builder is intended to be passed to the SourceCode function.

  Example:

        env.SourceCode('.', env.SCCS())

  Note that scons will fetch source files from SCCS subdirectories automatically, so configuring SCCS as demonstrated in the above example should only be necessary if you are fetching from s.SCCS files in the same directory as the source files, or if you need to explicitly specify SCCS for a specific subdirectory.

SConscript(scripts, [exports, variant_dir, src_dir, duplicate])
env.SConscript(scripts, [exports, variant_dir, src_dir, duplicate])
SConscript(dirs=subdirs, [name=script, exports, variant_dir, src_dir, duplicate])
env.SConscript(dirs=subdirs, [name=script, exports, variant_dir, src_dir, duplicate])
  This tells scons to execute one or more subsidiary SConscript (configuration) files. There are two ways to call the SConscript() function.

  The first way you can call SConscript() is to explicitly specify one or more scripts as the first argument. A single script may be specified as a string; multiple scripts must be specified as a list (either explicitly or as created by a function like Split()).

  The second way you can call SConscript() is to specify a list of (sub)directory names as a dirs=subdirs keyword argument. In this case, scons will, by default, execute a subsidiary configuration file named SConscript in each of the specified directories. You may specify a name other than SConscript by supplying an optional name=script keyword argument.

  The optional exports argument provides a list of variable names or a dictionary of named values to export to the script(s). These variables are locally exported only to the specified script(s), and do not affect the global pool of variables used by the Export() function. The subsidiary script(s) must use the Import() function to import the variables.

  The optional variant_dir argument specifies that all of the target files (for example, object files and executables) that would normally be built in the subdirectory in which script resides should actually be built in variant_dir. variant_dir is interpreted relative to the directory of the calling SConscript file.

  The optional src_dir argument specifies that the source files from which the target files should be built can be found in src_dir. src_dir is interpreted relative to the directory of the calling SConscript file.

  By default, scons will link or copy (depending on the platform) all the source files into the variant directory tree. This behavior may be disabled by setting the optional duplicate argument to 0 (it is set to 1 by default), in which case scons will refer directly to the source files in their source directory when building target files. (Setting duplicate=0 is usually safe, and always more efficient than the default of duplicate=1, but it may cause build problems in certain end-cases, such as compiling from source files that are generated by the build.)

  Any variables returned by script using Return() will be returned by the call to SConscript().

  Examples:

        SConscript('subdir/SConscript')
        foo = SConscript('sub/SConscript', exports='env')
        SConscript('dir/SConscript', exports=['env', 'variable'])
        SConscript('src/SConscript', variant_dir='build', duplicate=0)
        SConscript('bld/SConscript', src_dir='src', exports='env variable')
        SConscript(dirs=['sub1', 'sub2'])
        SConscript(dirs=['sub3', 'sub4'], name='MySConscript')

SConscriptChdir(value)
env.SConscriptChdir(value)
  By default, scons changes its working directory to the directory in which each subsidiary SConscript file lives. This behavior may be disabled by specifying either:

        SConscriptChdir(0)
        env.SConscriptChdir(0)

  in which case scons will stay in the top-level directory while reading all SConscript files. (This may be necessary when building from repositories, when all the directories in which SConscript files may be found don't necessarily exist locally.) You may enable and disable this ability by calling SConscriptChdir() multiple times.

  Example:

        env = Environment()
        SConscriptChdir(0)
        SConscript('foo/SConscript')    # will not chdir to foo
        env.SConscriptChdir(1)
        SConscript('bar/SConscript')    # will chdir to bar

SConsignFile([file,dbm_module])
env.SConsignFile([file,dbm_module])
  This tells scons to store all file signatures in the specified database file. If the file name is omitted, .sconsign is used by default. (The actual file name(s) stored on disk may have an appropriated suffix appended by the dbm_module.) If file is not an absolute path name, the file is placed in the same directory as the top-level SConstruct file.

  If file is None, then scons will store file signatures in a separate .sconsign file in each directory, not in one global database file. (This was the default behavior prior to SCons 0.96.91 and 0.97.)

  The optional dbm_module argument can be used to specify which Python database module The default is to use a custom SCons.dblite module that uses pickled Python data structures, and which works on all Python versions from 1.5.2 on.

  Examples:

        # Explicitly stores signatures in ".sconsign.dblite"
        # in the top-level SConstruct directory (the
        # default behavior).
        SConsignFile()

        # Stores signatures in the file "etc/scons-signatures"
        # relative to the top-level SConstruct directory.
        SConsignFile("etc/scons-signatures")

        # Stores signatures in the specified absolute file name.
        SConsignFile("/home/me/SCons/signatures")

        # Stores signatures in a separate .sconsign file
        # in each directory.
        SConsignFile(None)

env.SetDefault(key=val, [...])
  Sets construction variables to default values specified with the keyword arguments if (and only if) the variables are not already set. The following statements are equivalent:

        env.SetDefault(FOO = 'foo')

        if not env.has_key('FOO'): env['FOO'] = 'foo'

SetOption(name, value)
env.SetOption(name, value)
  This function provides a way to set a select subset of the scons command line options from a SConscript file. The options supported are:

    clean
      which corresponds to -c, --clean and --remove;
    duplicate
      which corresponds to --duplicate;
    help
      which corresponds to -h and --help;
    implicit_cache
      which corresponds to --implicit-cache;
    max_drift
      which corresponds to --max-drift;
    no_exec
      which corresponds to -n, --no-exec, --just-print, --dry-run and --recon;
    num_jobs
      which corresponds to -j and --jobs;
    random
      which corresponds to --random; and
    stack_size
      which corresponds to --stack-size.

  See the documentation for the corresponding command line object for information about each specific option.

  Example:

        SetOption('max_drift', 1)

SideEffect(side_effect, target)
env.SideEffect(side_effect, target)
  Declares side_effect as a side effect of building target. Both side_effect and target can be a list, a file name, or a node. A side effect is a target that is created as a side effect of building other targets. For example, a Windows PDB file is created as a side effect of building the .obj files for a static library. If a target is a side effect of multiple build commands, scons will ensure that only one set of commands is executed at a time. Consequently, you only need to use this method for side-effect targets that are built as a result of multiple build commands.

SourceCode(entries, builder)
env.SourceCode(entries, builder)
  Arrange for non-existent source files to be fetched from a source code management system using the specified builder. The specified entries may be a Node, string or list of both, and may represent either individual source files or directories in which source files can be found.

  For any non-existent source files, scons will search up the directory tree and use the first SourceCode builder it finds. The specified builder may be None, in which case scons will not use a builder to fetch source files for the specified entries, even if a SourceCode builder has been specified for a directory higher up the tree.

  scons will, by default, fetch files from SCCS or RCS subdirectories without explicit configuration. This takes some extra processing time to search for the necessary source code management files on disk. You can avoid these extra searches and speed up your build a little by disabling these searches as follows:

        env.SourceCode('.', None)

  Note that if the specified builder is one you create by hand, it must have an associated construction environment to use when fetching a source file.

  scons provides a set of canned factory functions that return appropriate Builders for various popular source code management systems. Canonical examples of invocation include:

        env.SourceCode('.', env.BitKeeper('/usr/local/BKsources'))
        env.SourceCode('src', env.CVS('/usr/local/CVSROOT'))
        env.SourceCode('/', env.RCS())
        env.SourceCode(['f1.c', 'f2.c'], env.SCCS())
        env.SourceCode('no_source.c', None)

env.subst(input, [raw, target, source, conv])
  Performs construction variable interpolation on the specified string or sequence argument input.

  By default, leading or trailing white space will be removed from the result. and all sequences of white space will be compressed to a single space character. Additionally, any $( and $) character sequences will be stripped from the returned string, The optional raw argument may be set to 1 if you want to preserve white space and $(-$) sequences. The raw argument may be set to 2 if you want to strip all characters between any $( and $) pairs (as is done for signature calculation).

  If the input is a sequence (list or tuple), the individual elements of the sequence will be expanded, and the results will be returned as a list.

  The optional target and source keyword arguments must be set to lists of target and source nodes, respectively, if you want the $TARGET, $TARGETS, $SOURCE and $SOURCES to be available for expansion. This is usually necessary if you are calling env.subst() from within a Python function used as an SCons action.

  Returned string values or sequence elements are converted to their string representation by default. The optional conv argument may specify a conversion function that will be used in place of the default. For example, if you want Python objects (including SCons Nodes) to be returned as Python objects, you can use the Python lambda idiom to pass in an unnamed function that simply returns its unconverted argument.

  Example:

        print env.subst("The C compiler is: $CC")

        def compile(target, source, env):
            sourceDir = env.subst("${SOURCE.srcdir}",
                                  target=target,
                                  source=source)

        source_nodes = env.subst('$EXPAND_TO_NODELIST',
                                 conv=lambda x: x)

SourceSignatures(type)
env.SourceSignatures(type)
  Note: Although it is not yet officially deprecated, use of this function is discouraged. See the Decider() function for a more flexible and straightforward way to configure SCons' decision-making.

  The SourceSignatures() function tells scons how to decide if a source file (a file that is not built from any other files) has changed since the last time it was used to build a particular target file. Legal values are MD5 or timestamp.

  If the environment method is used, the specified type of source signature is only used when deciding whether targets built with that environment are up-to-date or must be rebuilt. If the global function is used, the specified type of source signature becomes the default used for all decisions about whether targets are up-to-date.

  MD5 means scons decides that a source file has changed if the MD5 checksum of its contents has changed since the last time it was used to rebuild a particular target file.

  timestamp means scons decides that a source file has changed if its timestamp (modification time) has changed since the last time it was used to rebuild a particular target file. (Note that although this is similar to the behavior of Make, by default it will also rebuild if the dependency is older than the last time it was used to rebuild the target file.)

  There is no different between the two behaviors for Python Value() node objects.

  MD5 signatures take longer to compute, but are more accurate than timestamp signatures. The default value is MD5.

  Note that the default TargetSignatures() setting (see below) is to use this SourceSignatures() setting for any target files that are used to build other target files. Consequently, changing the value of SourceSignatures() will, by default, affect the up-to-date decision for all files in the build (or all files built with a specific construction environment when env.SourceSignatures() is used).

Split(arg)
env.Split(arg)
  Returns a list of file names or other objects. If arg is a string, it will be split on strings of white-space characters within the string, making it easier to write long lists of file names. If arg is already a list, the list will be returned untouched. If arg is any other type of object, it will be returned as a list containing just the object.

  Example:

        files = Split("f1.c f2.c f3.c")
        files = env.Split("f4.c f5.c f6.c")
        files = Split("""
                f7.c
                f8.c
                f9.c
        """)

Tag(node, tags)
  Annotates file or directory Nodes with information about how the Package() Builder should package those files or directories. All tags are optional.

  Examples:

        # makes sure the built library will be installed with 0644 file
        # access mode
        Tag( Library( 'lib.c' ), UNIX_ATTR="0644" )

        # marks file2.txt to be a documentation file
        Tag( 'file2.txt', DOC )

  </summary> </builder>

TargetSignatures(type)
env.TargetSignatures(type)
  Note: Although it is not yet officially deprecated, use of this function is discouraged. See the Decider() function for a more flexible and straightforward way to configure SCons' decision-making.

  The TargetSignatures() function tells scons how to decide if a target file (a file that is built from any other files) has changed since the last time it was used to build some other target file. Legal values are build; content (or its synonym MD5); timestamp; or source.

  If the environment method is used, the specified type of target signature is only used for targets built with that environment. If the global function is used, the specified type of signature becomes the default used for all target files that don't have an explicit target signature type specified for their environments.

  content (or its synonym MD5) means scons decides that a target file has changed if the MD5 checksum of its contents has changed since the last time it was used to rebuild some other target file. This means scons will open up MD5 sum the contents of target files after they're built, and may decide that it does not need to rebuild "downstream" target files if a file was rebuilt with exactly the same contents as the last time.

  timestamp means scons decides that a target file has changed if its timestamp (modification time) has changed since the last time it was used to rebuild some other target file. (Note that although this is similar to the behavior of Make, by default it will also rebuild if the dependency is older than the last time it was used to rebuild the target file.)

  source means scons decides that a target file has changed as specified by the corresponding SourceSignatures() setting (MD5 or timestamp). This means that scons will treat all input files to a target the same way, regardless of whether they are source files or have been built from other files.

  build means scons decides that a target file has changed if it has been rebuilt in this invocation or if its content or timestamp have changed as specified by the corresponding SourceSignatures() setting. This "propagates" the status of a rebuilt file so that other "downstream" target files will always be rebuilt, even if the contents or the timestamp have not changed.

  build signatures are fastest because content (or MD5) signatures take longer to compute, but are more accurate than timestamp signatures, and can prevent unnecessary "downstream" rebuilds when a target file is rebuilt to the exact same contents as the previous build. The source setting provides the most consistent behavior when other target files may be rebuilt from both source and target input files. The default value is source.

  Because the default setting is source, using SourceSignatures() is generally preferable to TargetSignatures(), so that the up-to-date decision will be consistent for all files (or all files built with a specific construction environment). Use of TargetSignatures() provides specific control for how built target files affect their "downstream" dependencies.

Tool(string[,toolpath, **kw])
  Returns a callable object that can be used to initialize a construction environment using the tools keyword of the Environment() method. The object may be called with a construction environment as an argument, in which case the object will add the necessary variables to the construction environment and the name of the tool will be added to the $TOOLS construction variable.

  Additional keyword arguments are passed to the tool's generate() method.

  Examples:

        env = Environment(tools = [ Tool('msvc') ])

        env = Environment()
        t = Tool('msvc')
        t(env)  # adds 'msvc' to the TOOLS variable
        u = Tool('opengl', toolpath = ['tools'])
        u(env)  # adds 'opengl' to the TOOLS variable

env.Tool(string[,toolpath, **kw])
  Applies the callable object for the specified tool string to the environment through which the method was called.

  Additional keyword arguments are passed to the tool's generate() method.

        env.Tool('gcc')
        env.Tool('opengl', toolpath = ['build/tools'])

Value(value, [built_value])
env.Value(value, [built_value])
  Returns a Node object representing the specified Python value. Value Nodes can be used as dependencies of targets. If the result of calling str(value) changes between SCons runs, any targets depending on Value(value) will be rebuilt. (This is true even when using timestamps to decide if files are up-to-date.) When using timestamp source signatures, Value Nodes' timestamps are equal to the system time when the Node is created.

  The returned Value Node object has a write() method that can be used to "build" a Value Node by setting a new value. The optional built_value argument can be specified when the Value Node is created to indicate the Node should already be considered "built." There is a corresponding read() method that will return the built value of the Node.

  Examples:

        env = Environment()

        def create(target, source, env):
            # A function that will write a 'prefix=$SOURCE'
            # string into the file name specified as the
            # $TARGET.
            f = open(str(target[0]), 'wb')
            f.write('prefix=' + source[0].get_contents())

        # Fetch the prefix= argument, if any, from the command
        # line, and use /usr/local as the default.
        prefix = ARGUMENTS.get('prefix', '/usr/local')

        # Attach a .Config() builder for the above function action
        # to the construction environment.
        env['BUILDERS']['Config'] = Builder(action = create)
        env.Config(target = 'package-config', source = Value(prefix))

        def build_value(target, source, env):
            # A function that "builds" a Python Value by updating
            # the the Python value with the contents of the file
            # specified as the source of the Builder call ($SOURCE).
            target[0].write(source[0].get_contents())

        output = env.Value('before')
        input = env.Value('after')

        # Attach a .UpdateValue() builder for the above function
        # action to the construction environment.
        env['BUILDERS']['UpdateValue'] = Builder(action = build_value)
        env.UpdateValue(target = Value(output), source = Value(input))

VariantDir(variant_dir, src_dir, [duplicate])
env.VariantDir(variant_dir, src_dir, [duplicate])
  This specifies a variant directory tree variant_dir in which to build all derived files that would normally be built under src_dir. Multiple directory trees can be set up for multiple build variants. src_dir must be underneath the SConstruct file's directory, and variant_dir may not be underneath the src_dir .

  The default behavior is for scons to duplicate all of the files in the tree underneath src_dir into variant_dir, and then build the derived files within the copied tree. (The duplication is performed by linking or copying, depending on the platform; see also the --duplicate option.) This guarantees correct builds regardless of whether intermediate source files are generated during the build, where preprocessors or other scanners search for included files, or whether individual compilers or other invoked tools are hard-coded to put derived files in the same directory as source files.

  This behavior of making a complete copy of the source tree may be disabled by setting duplicate to 0. This will cause scons to invoke Builders using the path names of source files in src_dir and the path names of derived files within variant_dir. This is always more efficient than duplicate=1, and is usually safe for most builds. Specifying duplicate=0, however, may cause build problems if source files are generated during the build, or if any invoked tools are hard-coded to put derived files in the same directory as the source files.

  Note that specifying a VariantDir works most naturally with a subsidiary SConscript file in the source directory. However, you would then call the subsidiary SConscript file not in the source directory, but in the variant_dir , as if scons had made a virtual copy of the source tree regardless of the value of duplicate. This is how you tell scons which variant of a source tree to build. For example:

        VariantDir('build-variant1', 'src')
        SConscript('build-variant1/SConscript')
        VariantDir('build-variant2', 'src')
        SConscript('build-variant2/SConscript')

  See also the SConscript() function, described below, for another way to specify a variant directory in conjunction with calling a subsidiary SConscript file.)

WhereIs(program, [path, pathext, reject])
env.WhereIs(program, [path, pathext, reject])

  Searches for the specified executable program, returning the full path name to the program if it is found, and returning None if not. Searches the specified path, the value of the calling environment's PATH (env['ENV']['PATH']), or the user's current external PATH (os.environ['PATH']) by default. On Windows systems, searches for executable programs with any of the file extensions listed in the specified pathext, the calling environment's PATHEXT (env['ENV']['PATHEXT']) or the user's current PATHEXT (os.environ['PATHEXT']) by default. Will not select any path name or names in the specified reject list, if any.

### SConscript Variables

In addition to the global functions and methods, scons supports a number of Python variables that can be used in SConscript files to affect how you want the build to be performed. These variables may be accessed from custom Python modules that you import into an SConscript file by adding the following to the Python module:

      from SCons.Script import *

ARGLIST
  A list keyword=value arguments specified on the command line. Each element in the list is a tuple containing the (keyword,value) of the argument. The separate keyword and value elements of the tuple can be accessed by subscripting for element [0] and [1] of the tuple, respectively.

  Example:

        print "first keyword, value =", ARGLIST[0][0], ARGLIST[0][1]
        print "second keyword, value =", ARGLIST[1][0], ARGLIST[1][1]
        third_tuple = ARGLIST[2]
        print "third keyword, value =", third_tuple[0], third_tuple[1]
        for key, value in ARGLIST:
            # process key and value

ARGUMENTS
  A dictionary of all the keyword=value arguments specified on the command line. The dictionary is not in order, and if a given keyword has more than one value assigned to it on the command line, the last (right-most) value is the one in the ARGUMENTS dictionary.

  Example:

        if ARGUMENTS.get('debug', 0):
            env = Environment(CCFLAGS = '-g')
        else:
            env = Environment()

BUILD_TARGETS
  A list of the targets which scons will actually try to build, regardless of whether they were specified on the command line or via the Default() function or method. The elements of this list may be strings or nodes, so you should run the list through the Python str function to make sure any Node path names are converted to strings.

  Because this list may be taken from the list of targets specified using the Default() function or method, the contents of the list may change on each successive call to Default(). See the DEFAULT_TARGETS list, below, for additional information.

  Example:

        if 'foo' in BUILD_TARGETS:
            print "Don't forget to test the `foo' program!"
        if 'special/program' in BUILD_TARGETS:
            SConscript('special')

  Note that the BUILD_TARGETS list only contains targets expected listed on the command line or via calls to the Default() function or method. It does not contain all dependent targets that will be built as a result of making the sure the explicitly-specified targets are up to date.

COMMAND_LINE_TARGETS
  A list of the targets explicitly specified on the command line. If there are no targets specified on the command line, the list is empty. This can be used, for example, to take specific actions only when a certain target or targets is explicitly being built.

  Example:

        if 'foo' in COMMAND_LINE_TARGETS:
            print "Don't forget to test the `foo' program!"
        if 'special/program' in COMMAND_LINE_TARGETS:
            SConscript('special')

DEFAULT_TARGETS
  A list of the target nodes that have been specified using the Default() function or method. The elements of the list are nodes, so you need to run them through the Python str function to get at the path name for each Node.

  Example:

        print str(DEFAULT_TARGETS[0])
        if 'foo' in map(str, DEFAULT_TARGETS):
            print "Don't forget to test the `foo' program!"

  The contents of the DEFAULT_TARGETS list change on on each successive call to the Default() function:

        print map(str, DEFAULT_TARGETS)   # originally []
        Default('foo')
        print map(str, DEFAULT_TARGETS)   # now a node ['foo']
        Default('bar')
        print map(str, DEFAULT_TARGETS)   # now a node ['foo', 'bar']
        Default(None)
        print map(str, DEFAULT_TARGETS)   # back to []

  Consequently, be sure to use DEFAULT_TARGETS only after you've made all of your Default() calls, or else simply be careful of the order of these statements in your SConscript files so that you don't look for a specific default target before it's actually been added to the list.

### Construction Variables

A construction environment has an associated dictionary of construction variables that are used by built-in or user-supplied build rules. Construction variables must follow the same rules for Python identifiers: the initial character must be an underscore or letter, followed by any number of underscores, letters, or digits.

A number of useful construction variables are automatically defined by scons for each supported platform, and additional construction variables can be defined by the user. The following is a list of the automatically defined construction variables:

AR
  The static library archiver.

ARCHITECTURE
  Specifies the system architecture for which the package is being built. The default is the system architecture of the machine on which SCons is running. This is used to fill in the Architecture: field in an Ipkg control file, and as part of the name of a generated RPM file.

ARCOM
  The command line used to generate a static library from object files.

ARCOMSTR
  The string displayed when an object file is generated from an assembly-language source file. If this is not set, then $ARCOM (the command line) is displayed.

        env = Environment(ARCOMSTR = "Archiving $TARGET")

ARFLAGS
  General options passed to the static library archiver.

AS
  The assembler.

ASCOM
  The command line used to generate an object file from an assembly-language source file.

ASCOMSTR
  The string displayed when an object file is generated from an assembly-language source file. If this is not set, then $ASCOM (the command line) is displayed.

        env = Environment(ASCOMSTR = "Assembling $TARGET")

ASFLAGS
  General options passed to the assembler.

ASPPCOM
  The command line used to assemble an assembly-language source file into an object file after first running the file through the C preprocessor. Any options specified in the $ASFLAGS and $CPPFLAGS construction variables are included on this command line.

ASPPCOMSTR
  The string displayed when an object file is generated from an assembly-language source file after first running the file through the C preprocessor. If this is not set, then $ASPPCOM (the command line) is displayed.

        env = Environment(ASPPCOMSTR = "Assembling $TARGET")

ASPPFLAGS
  General options when an assembling an assembly-language source file into an object file after first running the file through the C preprocessor. The default is to use the value of $ASFLAGS.

BIBTEX
  The bibliography generator for the TeX formatter and typesetter and the LaTeX structured formatter and typesetter.

BIBTEXCOM
  The command line used to call the bibliography generator for the TeX formatter and typesetter and the LaTeX structured formatter and typesetter.

BIBTEXCOMSTR
  The string displayed when generating a bibliography for TeX or LaTeX. If this is not set, then $BIBTEXCOM (the command line) is displayed.

        env = Environment(BIBTEXCOMSTR = "Generating bibliography $TARGET")

BIBTEXFLAGS
  General options passed to the bibliography generator for the TeX formatter and typesetter and the LaTeX structured formatter and typesetter.

BITKEEPER
  The BitKeeper executable.

BITKEEPERCOM
  The command line for fetching source files using BitKeeper.

BITKEEPERCOMSTR
  The string displayed when fetching a source file using BitKeeper. If this is not set, then $BITKEEPERCOM (the command line) is displayed.

BITKEEPERGET
  The command ($BITKEEPER) and subcommand for fetching source files using BitKeeper.

BITKEEPERGETFLAGS
  Options that are passed to the BitKeeper get subcommand.

BUILDERS
  A dictionary mapping the names of the builders available through this environment to underlying Builder objects. Builders named Alias, CFile, CXXFile, DVI, Library, Object, PDF, PostScript, and Program are available by default. If you initialize this variable when an Environment is created:

        env = Environment(BUILDERS = {'NewBuilder' : foo})

  the default Builders will no longer be available. To use a new Builder object in addition to the default Builders, add your new Builder object like this:

        env = Environment()
        env.Append(BUILDERS = {'NewBuilder' : foo})

  or this:

        env = Environment()
        env['BUILDERS]['NewBuilder'] = foo

CC
  The C compiler.

CCCOM
  The command line used to compile a C source file to a (static) object file. Any options specified in the $CFLAGS, $CCFLAGS and $CPPFLAGS construction variables are included on this command line.

CCCOMSTR
  The string displayed when a C source file is compiled to a (static) object file. If this is not set, then $CCCOM (the command line) is displayed.

        env = Environment(CCCOMSTR = "Compiling static object $TARGET")

CCFLAGS
  General options that are passed to the C and C++ compilers.

CCPCHFLAGS
  Options added to the compiler command line to support building with precompiled headers. The default value expands expands to the appropriate Microsoft Visual C++ command-line options when the $PCH construction variable is set.

CCPDBFLAGS
  Options added to the compiler command line to support storing debugging information in a Microsoft Visual C++ PDB file. The default value expands expands to appropriate Microsoft Visual C++ command-line options when the $PDB construction variable is set.

  The Visual C++ compiler option that SCons uses by default to generate PDB information is /Z7. This works correctly with parallel (-j) builds because it embeds the debug information in the intermediate object files, as opposed to sharing a single PDB file between multiple object files. This is also the only way to get debug information embedded into a static library. Using the /Zi instead may yield improved link-time performance, although parallel builds will no longer work.

  You can generate PDB files with the /Zi switch by overriding the default $CCPDBFLAGS variable as follows:

        import SCons.Util
        env['CCPDBFLAGS'] = SCons.Util.CLVar(['${(PDB and "/Zi /Fd%s" % File(PDB)) or ""}'])

  An alternative would be to use the /Zi to put the debugging information in a separate .pdb file for each object file by overriding the $CCPDBFLAGS variable as follows:

        env['CCPDBFLAGS'] = '/Zi /Fd${TARGET}.pdb'

CCVERSION
  The version number of the C compiler. This may or may not be set, depending on the specific C compiler being used.

CFILESUFFIX
  The suffix for C source files. This is used by the internal CFile builder when generating C files from Lex (.l) or YACC (.y) input files. The default suffix, of course, is .c (lower case). On case-insensitive systems (like Windows), SCons also treats .C (upper case) files as C files.

CFLAGS
  General options that are passed to the C compiler (C only; not C++).

CHANGE_SPECFILE
  A hook for modifying the file that controls the packaging build (the .spec for RPM, the control for Ipkg, the .wxs for MSI). If set, the function will be called after the SCons template for the file has been written. XXX

CHANGELOG
  The name of a file containing the change log text to be included in the package. This is included as the %changelog section of the RPM .spec file.

_concat
  A function used to produce variables like $_CPPINCFLAGS. It takes four or five arguments: a prefix to concatenate onto each element, a list of elements, a suffix to concatenate onto each element, an environment for variable interpolation, and an optional function that will be called to transform the list before concatenation.

        env['_CPPINCFLAGS'] = '$( ${_concat(INCPREFIX, CPPPATH, INCSUFFIX, __env__, RDirs)} $)',

CONFIGUREDIR
  The name of the directory in which Configure context test files are written. The default is .sconf_temp in the top-level directory containing the SConstruct file.

CONFIGURELOG
  The name of the Configure context log file. The default is config.log in the top-level directory containing the SConstruct file.

_CPPDEFFLAGS
  An automatically-generated construction variable containing the C preprocessor command-line options to define values. The value of $_CPPDEFFLAGS is created by appending $CPPDEFPREFIX and $CPPDEFSUFFIX to the beginning and end of each directory in $CPPDEFINES.

CPPDEFINES
  A platform independent specification of C preprocessor definitions. The definitions will be added to command lines through the automatically-generated $_CPPDEFFLAGS construction variable (see above), which is constructed according to the type of value of $CPPDEFINES:

  If $CPPDEFINES is a string, the values of the $CPPDEFPREFIX and $CPPDEFSUFFIX construction variables will be added to the beginning and end.

        # Will add -Dxyz to POSIX compiler command lines,
        # and /Dxyz to Microsoft Visual C++ command lines.
        env = Environment(CPPDEFINES='xyz')

  If $CPPDEFINES is a list, the values of the $CPPDEFPREFIX and $CPPDEFSUFFIX construction variables will be appended to the beginning and end of each element in the list. If any element is a list or tuple, then the first item is the name being defined and the second item is its value:

        # Will add -DB=2 -DA to POSIX compiler command lines,
        # and /DB=2 /DA to Microsoft Visual C++ command lines.
        env = Environment(CPPDEFINES=[('B', 2), 'A'])

  If $CPPDEFINES is a dictionary, the values of the $CPPDEFPREFIX and $CPPDEFSUFFIX construction variables will be appended to the beginning and end of each item from the dictionary. The key of each dictionary item is a name being defined to the dictionary item's corresponding value; if the value is None, then the name is defined without an explicit value. Note that the resulting flags are sorted by keyword to ensure that the order of the options on the command line is consistent each time scons is run.

        # Will add -DA -DB=2 to POSIX compiler command lines,
        # and /DA /DB=2 to Microsoft Visual C++ command lines.
        env = Environment(CPPDEFINES={'B':2, 'A':None})

CPPDEFPREFIX
  The prefix used to specify preprocessor definitions on the C compiler command line. This will be appended to the beginning of each definition in the $CPPDEFINES construction variable when the $_CPPDEFFLAGS variable is automatically generated.

CPPDEFSUFFIX
  The suffix used to specify preprocessor definitions on the C compiler command line. This will be appended to the end of each definition in the $CPPDEFINES construction variable when the $_CPPDEFFLAGS variable is automatically generated.

CPPFLAGS
  User-specified C preprocessor options. These will be included in any command that uses the C preprocessor, including not just compilation of C and C++ source files via the $CCCOM, $SHCCCOM, $CXXCOM and $SHCXXCOM command lines, but also the $FORTRANPPCOM, $SHFORTRANPPCOM, $F77PPCOM and $SHF77PPCOM command lines used to compile a Fortran source file, and the $ASPPCOM command line used to assemble an assembly language source file, after first running each file through the C preprocessor. Note that this variable does not contain -I (or similar) include search path options that scons generates automatically from $CPPPATH. See $_CPPINCFLAGS, below, for the variable that expands to those options.

_CPPINCFLAGS
  An automatically-generated construction variable containing the C preprocessor command-line options for specifying directories to be searched for include files. The value of $_CPPINCFLAGS is created by appending $INCPREFIX and $INCSUFFIX to the beginning and end of each directory in $CPPPATH.

CPPPATH
  The list of directories that the C preprocessor will search for include directories. The C/C++ implicit dependency scanner will search these directories for include files. Don't explicitly put include directory arguments in CCFLAGS or CXXFLAGS because the result will be non-portable and the directories will not be searched by the dependency scanner. Note: directory names in CPPPATH will be looked-up relative to the SConscript directory when they are used in a command. To force scons to look-up a directory relative to the root of the source tree use #:

        env = Environment(CPPPATH='#/include')

  The directory look-up can also be forced using the Dir() function:

        include = Dir('include')
        env = Environment(CPPPATH=include)

  The directory list will be added to command lines through the automatically-generated $_CPPINCFLAGS construction variable, which is constructed by appending the values of the $INCPREFIX and $INCSUFFIX construction variables to the beginning and end of each directory in $CPPPATH. Any command lines you define that need the CPPPATH directory list should include $_CPPINCFLAGS:

        env = Environment(CCCOM="my_compiler $_CPPINCFLAGS -c -o $TARGET $SOURCE")

CPPSUFFIXES
  The list of suffixes of files that will be scanned for C preprocessor implicit dependencies (#include lines). The default list is:

        [".c", ".C", ".cxx", ".cpp", ".c++", ".cc",
         ".h", ".H", ".hxx", ".hpp", ".hh",
         ".F", ".fpp", ".FPP",
         ".m", ".mm",
         ".S", ".spp", ".SPP"]

CVS
  The CVS executable.

CVSCOFLAGS
  Options that are passed to the CVS checkout subcommand.

CVSCOM
  The command line used to fetch source files from a CVS repository.

CVSCOMSTR
  The string displayed when fetching a source file from a CVS repository. If this is not set, then $CVSCOM (the command line) is displayed.

CVSFLAGS
  General options that are passed to CVS. By default, this is set to -d $CVSREPOSITORY to specify from where the files must be fetched.

CVSREPOSITORY
  The path to the CVS repository. This is referenced in the default $CVSFLAGS value.

CXX
  The C++ compiler.

CXXCOM
  The command line used to compile a C++ source file to an object file. Any options specified in the $CXXFLAGS and $CPPFLAGS construction variables are included on this command line.

CXXCOMSTR
  The string displayed when a C++ source file is compiled to a (static) object file. If this is not set, then $CXXCOM (the command line) is displayed.

        env = Environment(CXXCOMSTR = "Compiling static object $TARGET")

CXXFILESUFFIX
  The suffix for C++ source files. This is used by the internal CXXFile builder when generating C++ files from Lex (.ll) or YACC (.yy) input files. The default suffix is .cc. SCons also treats files with the suffixes .cpp, .cxx, .c++, and .C++ as C++ files, and files with .mm suffixes as Objective C++ files. On case-sensitive systems (Linux, UNIX, and other POSIX-alikes), SCons also treats .C (upper case) files as C++ files.

CXXFLAGS
  General options that are passed to the C++ compiler. By default, this includes the value of $CCFLAGS, so that setting $CCFLAGS affects both C and C++ compilation. If you want to add C++-specific flags, you must set or override the value of $CXXFLAGS.

CXXVERSION
  The version number of the C++ compiler. This may or may not be set, depending on the specific C++ compiler being used.

DESCRIPTION
  A long description of the project being packaged. This is included in the relevant section of the file that controls the packaging build.

DESCRIPTION_lang
  A language-specific long description for the specified lang. This is used to populate a %description -l section of an RPM .spec file.

Dir
  A function that converts a string into a Dir instance relative to the target being built.

Dirs
  A function that converts a list of strings into a list of Dir instances relative to the target being built.

DSUFFIXES
  The list of suffixes of files that will be scanned for imported D package files. The default list is:

        ['.d']

DVIPDF
  The TeX DVI file to PDF file converter.

DVIPDFCOM
  The command line used to convert TeX DVI files into a PDF file.

DVIPDFCOMSTR
  The string displayed when a TeX DVI file is converted into a PDF file. If this is not set, then $DVIPDFCOM (the command line) is displayed.

DVIPDFFLAGS
  General options passed to the TeX DVI file to PDF file converter.

DVIPS
  The TeX DVI file to PostScript converter.

DVIPSFLAGS
  General options passed to the TeX DVI file to PostScript converter.

ENV
  A dictionary of environment variables to use when invoking commands. When $ENV is used in a command all list values will be joined using the path separator and any other non-string values will simply be coerced to a string. Note that, by default, scons does not propagate the environment in force when you execute scons to the commands used to build target files. This is so that builds will be guaranteed repeatable regardless of the environment variables set at the time scons is invoked.

  If you want to propagate your environment variables to the commands executed to build target files, you must do so explicitly:

        import os
        env = Environment(ENV = os.environ)

  Note that you can choose only to propagate certain environment variables. A common example is the system PATH environment variable, so that scons uses the same utilities as the invoking shell (or other process):

        import os
        env = Environment(ENV = {'PATH' : os.environ['PATH']})

ESCAPE
  A function that will be called to escape shell special characters in command lines. The function should take one argument: the command line string to escape; and should return the escaped command line.

F77
  The Fortran 77 compiler. You should normally set the $FORTRAN variable, which specifies the default Fortran compiler for all Fortran versions. You only need to set $F77 if you need to use a specific compiler or compiler version for Fortran 77 files.

F77COM
  The command line used to compile a Fortran 77 source file to an object file. You only need to set $F77COM if you need to use a specific command line for Fortran 77 files. You should normally set the $FORTRANCOM variable, which specifies the default command line for all Fortran versions.

F77COMSTR
  The string displayed when a Fortran 77 source file is compiled to an object file. If this is not set, then $F77COM or $FORTRANCOM (the command line) is displayed.

F77FLAGS
  General user-specified options that are passed to the Fortran 77 compiler. Note that this variable does not contain -I (or similar) include search path options that scons generates automatically from $F77PATH. See $_F77INCFLAGS below, for the variable that expands to those options. You only need to set $F77FLAGS if you need to define specific user options for Fortran 77 files. You should normally set the $FORTRANFLAGS variable, which specifies the user-specified options passed to the default Fortran compiler for all Fortran versions.

_F77INCFLAGS
  An automatically-generated construction variable containing the Fortran 77 compiler command-line options for specifying directories to be searched for include files. The value of $_F77INCFLAGS is created by appending $INCPREFIX and $INCSUFFIX to the beginning and end of each directory in $F77PATH.

F77PATH
  The list of directories that the Fortran 77 compiler will search for include directories. The implicit dependency scanner will search these directories for include files. Don't explicitly put include directory arguments in $F77FLAGS because the result will be non-portable and the directories will not be searched by the dependency scanner. Note: directory names in $F77PATH will be looked-up relative to the SConscript directory when they are used in a command. To force scons to look-up a directory relative to the root of the source tree use #: You only need to set $F77PATH if you need to define a specific include path for Fortran 77 files. You should normally set the $FORTRANPATH variable, which specifies the include path for the default Fortran compiler for all Fortran versions.

        env = Environment(F77PATH='#/include')

  The directory look-up can also be forced using the Dir() function:

        include = Dir('include')
        env = Environment(F77PATH=include)

  The directory list will be added to command lines through the automatically-generated $_F77INCFLAGS construction variable, which is constructed by appending the values of the $INCPREFIX and $INCSUFFIX construction variables to the beginning and end of each directory in $F77PATH. Any command lines you define that need the F77PATH directory list should include $_F77INCFLAGS:

        env = Environment(F77COM="my_compiler $_F77INCFLAGS -c -o $TARGET $SOURCE")

F77PPCOM
  The command line used to compile a Fortran 77 source file to an object file after first running the file through the C preprocessor. Any options specified in the $F77FLAGS and $CPPFLAGS construction variables are included on this command line. You only need to set $F77PPCOM if you need to use a specific C-preprocessor command line for Fortran 77 files. You should normally set the $FORTRANPPCOM variable, which specifies the default C-preprocessor command line for all Fortran versions.

F77PPCOMSTR
  The string displayed when a Fortran 77 source file is compiled to an object file after first running the file through the C preprocessor. If this is not set, then $F77PPCOM or $FORTRANPPCOM (the command line) is displayed.

F90
  The Fortran 90 compiler. You should normally set the $FORTRAN variable, which specifies the default Fortran compiler for all Fortran versions. You only need to set $F90 if you need to use a specific compiler or compiler version for Fortran 90 files.

F90COM
  The command line used to compile a Fortran 90 source file to an object file. You only need to set $F90COM if you need to use a specific command line for Fortran 90 files. You should normally set the $FORTRANCOM variable, which specifies the default command line for all Fortran versions.

F90COMSTR
  The string displayed when a Fortran 90 source file is compiled to an object file. If this is not set, then $F90COM or $FORTRANCOM (the command line) is displayed.

F90FLAGS
  General user-specified options that are passed to the Fortran 90 compiler. Note that this variable does not contain -I (or similar) include search path options that scons generates automatically from $F90PATH. See $_F90INCFLAGS below, for the variable that expands to those options. You only need to set $F90FLAGS if you need to define specific user options for Fortran 90 files. You should normally set the $FORTRANFLAGS variable, which specifies the user-specified options passed to the default Fortran compiler for all Fortran versions.

_F90INCFLAGS
  An automatically-generated construction variable containing the Fortran 90 compiler command-line options for specifying directories to be searched for include files. The value of $_F90INCFLAGS is created by appending $INCPREFIX and $INCSUFFIX to the beginning and end of each directory in $F90PATH.

F90PATH
  The list of directories that the Fortran 90 compiler will search for include directories. The implicit dependency scanner will search these directories for include files. Don't explicitly put include directory arguments in $F90FLAGS because the result will be non-portable and the directories will not be searched by the dependency scanner. Note: directory names in $F90PATH will be looked-up relative to the SConscript directory when they are used in a command. To force scons to look-up a directory relative to the root of the source tree use #: You only need to set $F90PATH if you need to define a specific include path for Fortran 90 files. You should normally set the $FORTRANPATH variable, which specifies the include path for the default Fortran compiler for all Fortran versions.

        env = Environment(F90PATH='#/include')

  The directory look-up can also be forced using the Dir() function:

        include = Dir('include')
        env = Environment(F90PATH=include)

  The directory list will be added to command lines through the automatically-generated $_F90INCFLAGS construction variable, which is constructed by appending the values of the $INCPREFIX and $INCSUFFIX construction variables to the beginning and end of each directory in $F90PATH. Any command lines you define that need the F90PATH directory list should include $_F90INCFLAGS:

        env = Environment(F90COM="my_compiler $_F90INCFLAGS -c -o $TARGET $SOURCE")

F90PPCOM
  The command line used to compile a Fortran 90 source file to an object file after first running the file through the C preprocessor. Any options specified in the $F90FLAGS and $CPPFLAGS construction variables are included on this command line. You only need to set $F90PPCOM if you need to use a specific C-preprocessor command line for Fortran 90 files. You should normally set the $FORTRANPPCOM variable, which specifies the default C-preprocessor command line for all Fortran versions.

F90PPCOMSTR
  The string displayed when a Fortran 90 source file is compiled after first running the file through the C preprocessor. If this is not set, then $F90PPCOM or $FORTRANPPCOM (the command line) is displayed.

F95
  The Fortran 95 compiler. You should normally set the $FORTRAN variable, which specifies the default Fortran compiler for all Fortran versions. You only need to set $F95 if you need to use a specific compiler or compiler version for Fortran 95 files.

F95COM
  The command line used to compile a Fortran 95 source file to an object file. You only need to set $F95COM if you need to use a specific command line for Fortran 95 files. You should normally set the $FORTRANCOM variable, which specifies the default command line for all Fortran versions.

F95COMSTR
  The string displayed when a Fortran 95 source file is compiled to an object file. If this is not set, then $F95COM or $FORTRANCOM (the command line) is displayed.

F95FLAGS
  General user-specified options that are passed to the Fortran 95 compiler. Note that this variable does not contain -I (or similar) include search path options that scons generates automatically from $F95PATH. See $_F95INCFLAGS below, for the variable that expands to those options. You only need to set $F95FLAGS if you need to define specific user options for Fortran 95 files. You should normally set the $FORTRANFLAGS variable, which specifies the user-specified options passed to the default Fortran compiler for all Fortran versions.

_F95INCFLAGS
  An automatically-generated construction variable containing the Fortran 95 compiler command-line options for specifying directories to be searched for include files. The value of $_F95INCFLAGS is created by appending $INCPREFIX and $INCSUFFIX to the beginning and end of each directory in $F95PATH.

F95PATH
  The list of directories that the Fortran 95 compiler will search for include directories. The implicit dependency scanner will search these directories for include files. Don't explicitly put include directory arguments in $F95FLAGS because the result will be non-portable and the directories will not be searched by the dependency scanner. Note: directory names in $F95PATH will be looked-up relative to the SConscript directory when they are used in a command. To force scons to look-up a directory relative to the root of the source tree use #: You only need to set $F95PATH if you need to define a specific include path for Fortran 95 files. You should normally set the $FORTRANPATH variable, which specifies the include path for the default Fortran compiler for all Fortran versions.

        env = Environment(F95PATH='#/include')

  The directory look-up can also be forced using the Dir() function:

        include = Dir('include')
        env = Environment(F95PATH=include)

  The directory list will be added to command lines through the automatically-generated $_F95INCFLAGS construction variable, which is constructed by appending the values of the $INCPREFIX and $INCSUFFIX construction variables to the beginning and end of each directory in $F95PATH. Any command lines you define that need the F95PATH directory list should include $_F95INCFLAGS:

        env = Environment(F95COM="my_compiler $_F95INCFLAGS -c -o $TARGET $SOURCE")

F95PPCOM
  The command line used to compile a Fortran 95 source file to an object file after first running the file through the C preprocessor. Any options specified in the $F95FLAGS and $CPPFLAGS construction variables are included on this command line. You only need to set $F95PPCOM if you need to use a specific C-preprocessor command line for Fortran 95 files. You should normally set the $FORTRANPPCOM variable, which specifies the default C-preprocessor command line for all Fortran versions.

F95PPCOMSTR
  The string displayed when a Fortran 95 source file is compiled to an object file after first running the file through the C preprocessor. If this is not set, then $F95PPCOM or $FORTRANPPCOM (the command line) is displayed.

File
  A function that converts a string into a File instance relative to the target being built.

FORTRAN
  The default Fortran compiler for all versions of Fortran.

FORTRANCOM
  The command line used to compile a Fortran source file to an object file. By default, any options specified in the $FORTRANFLAGS, $CPPFLAGS, $_CPPDEFFLAGS, $_FORTRANMODFLAG, and $_FORTRANINCFLAGS construction variables are included on this command line.

FORTRANCOMSTR
  The string displayed when a Fortran source file is compiled to an object file. If this is not set, then $FORTRANCOM (the command line) is displayed.

FORTRANFLAGS
  General user-specified options that are passed to the Fortran compiler. Note that this variable does not contain -I (or similar) include or module search path options that scons generates automatically from $FORTRANPATH. See $_FORTRANINCFLAGS and $_FORTRANMODFLAG, below, for the variables that expand those options.

_FORTRANINCFLAGS
  An automatically-generated construction variable containing the Fortran compiler command-line options for specifying directories to be searched for include files and module files. The value of $_FORTRANINCFLAGS is created by prepending/appending $INCPREFIX and $INCSUFFIX to the beginning and end of each directory in $FORTRANPATH.

FORTRANMODDIR
  Directory location where the Fortran compiler should place any module files it generates. This variable is empty, by default. Some Fortran compilers will internally append this directory in the search path for module files, as well.

FORTRANMODDIRPREFIX
  The prefix used to specify a module directory on the Fortran compiler command line. This will be appended to the beginning of the directory in the $FORTRANMODDIR construction variables when the $_FORTRANMODFLAG variables is automatically generated.

FORTRANMODDIRSUFFIX
  The suffix used to specify a module directory on the Fortran compiler command line. This will be appended to the beginning of the directory in the $FORTRANMODDIR construction variables when the $_FORTRANMODFLAG variables is automatically generated.

_FORTRANMODFLAG
  An automatically-generated construction variable containing the Fortran compiler command-line option for specifying the directory location where the Fortran compiler should place any module files that happen to get generated during compilation. The value of $_FORTRANMODFLAG is created by prepending/appending $FORTRANMODDIRPREFIX and $FORTRANMODDIRSUFFIX to the beginning and end of the directory in $FORTRANMODDIR.

FORTRANMODPREFIX
  The module file prefix used by the Fortran compiler. SCons assumes that the Fortran compiler follows the quasi-standard naming convention for module files of module_name.mod. As a result, this variable is left empty, by default. For situations in which the compiler does not necessarily follow the normal convention, the user may use this variable. Its value will be appended to every module file name as scons attempts to resolve dependencies.

FORTRANMODSUFFIX
  The module file suffix used by the Fortran compiler. SCons assumes that the Fortran compiler follows the quasi-standard naming convention for module files of module_name.mod. As a result, this variable is set to ".mod", by default. For situations in which the compiler does not necessarily follow the normal convention, the user may use this variable. Its value will be appended to every module file name as scons attempts to resolve dependencies.

FORTRANPATH
  The list of directories that the Fortran compiler will search for include files and (for some compilers) module files. The Fortran implicit dependency scanner will search these directories for include files (but not module files since they are autogenerated and, as such, may not actually exist at the time the scan takes place). Don't explicitly put include directory arguments in FORTRANFLAGS because the result will be non-portable and the directories will not be searched by the dependency scanner. Note: directory names in FORTRANPATH will be looked-up relative to the SConscript directory when they are used in a command. To force scons to look-up a directory relative to the root of the source tree use #:

        env = Environment(FORTRANPATH='#/include')

  The directory look-up can also be forced using the Dir() function:

        include = Dir('include')
        env = Environment(FORTRANPATH=include)

  The directory list will be added to command lines through the automatically-generated $_FORTRANINCFLAGS construction variable, which is constructed by appending the values of the $INCPREFIX and $INCSUFFIX construction variables to the beginning and end of each directory in $FORTRANPATH. Any command lines you define that need the FORTRANPATH directory list should include $_FORTRANINCFLAGS:

        env = Environment(FORTRANCOM="my_compiler $_FORTRANINCFLAGS -c -o $TARGET $SOURCE")

FORTRANPPCOM
  The command line used to compile a Fortran source file to an object file after first running the file through the C preprocessor. By default, any options specified in the $FORTRANFLAGS, $CPPFLAGS, $_CPPDEFFLAGS, $_FORTRANMODFLAG, and $_FORTRANINCFLAGS construction variables are included on this command line.

FORTRANPPCOMSTR
  The string displayed when a Fortran source file is compiled to an object file after first running the file throught the C preprocessor. If this is not set, then $FORTRANPPCOM (the command line) is displayed.

FORTRANSUFFIXES
  The list of suffixes of files that will be scanned for Fortran implicit dependencies (INCLUDE lines and USE statements). The default list is:

        [".f", ".F", ".for", ".FOR", ".ftn", ".FTN", ".fpp", ".FPP",
        ".f77", ".F77", ".f90", ".F90", ".f95", ".F95"]

FRAMEWORKPATH
  On Mac OS X with gcc, a list containing the paths to search for frameworks. Used by the compiler to find framework-style includes like #include <Fmwk/Header.h>. Used by the linker to find user-specified frameworks when linking (see $FRAMEWORKS). For example:

         env.AppendUnique(FRAMEWORKPATH='#myframeworkdir')

  will add

          ... -Fmyframeworkdir

  to the compiler and linker command lines.

_FRAMEWORKPATH
  On Mac OS X with gcc, an automatically-generated construction variable containing the linker command-line options corresponding to $FRAMEWORKPATH.

FRAMEWORKPATHPREFIX
  On Mac OS X with gcc, the prefix to be used for the FRAMEWORKPATH entries. (see $FRAMEWORKPATH). The default value is -F.

FRAMEWORKPREFIX
  On Mac OS X with gcc, the prefix to be used for linking in frameworks (see $FRAMEWORKS). The default value is -framework.

_FRAMEWORKS
  On Mac OS X with gcc, an automatically-generated construction variable containing the linker command-line options for linking with FRAMEWORKS.

FRAMEWORKS
  On Mac OS X with gcc, a list of the framework names to be linked into a program or shared library or bundle. The default value is the empty list. For example:

         env.AppendUnique(FRAMEWORKS=Split('System Cocoa SystemConfiguration'))

FRAMEWORKSFLAGS
  On Mac OS X with gcc, general user-supplied frameworks options to be added at the end of a command line building a loadable module. (This has been largely superceded by the $FRAMEWORKPATH, $FRAMEWORKPATHPREFIX, $FRAMEWORKPREFIX and $FRAMEWORKS variables described above.)

GS
  The Ghostscript program used to convert PostScript to PDF files.

GSCOM
  The Ghostscript command line used to convert PostScript to PDF files.

GSCOMSTR
  The string displayed when Ghostscript is used to convert a PostScript file to a PDF file. If this is not set, then $GSCOM (the command line) is displayed.

GSFLAGS
  General options passed to the Ghostscript program when converting PostScript to PDF files.

IDLSUFFIXES
  The list of suffixes of files that will be scanned for IDL implicit dependencies (#include or import lines). The default list is:

        [".idl", ".IDL"]

IMPLICIT_COMMAND_DEPENDENCIES
  Controls whether or not SCons will add implicit dependencies for the commands executed to build targets.

  By default, SCons will add to each target an implicit dependency on the command represented by the first argument on any command line it executes. The specific file for the dependency is found by searching the PATH variable in the ENV environment used to execute the command.

  If the construction variable $IMPLICIT_COMMAND_DEPENDENCIES is set to a false value (None, False, 0, etc.), then the implicit dependency will not be added to the targets built with that construction environment.

        env = Environment(IMPLICIT_COMMAND_DEPENDENCIES = 0)

INCPREFIX
  The prefix used to specify an include directory on the C compiler command line. This will be appended to the beginning of each directory in the $CPPPATH and $FORTRANPATH construction variables when the $_CPPINCFLAGS and $_FORTRANINCFLAGS variables are automatically generated.

INCSUFFIX
  The suffix used to specify an include directory on the C compiler command line. This will be appended to the end of each directory in the $CPPPATH and $FORTRANPATH construction variables when the $_CPPINCFLAGS and $_FORTRANINCFLAGS variables are automatically generated.

INSTALL
  A function to be called to install a file into a destination file name. The default function copies the file into the destination (and sets the destination file's mode and permission bits to match the source file's). The function takes the following arguments:

        def install(dest, source, env):

  dest is the path name of the destination file. source is the path name of the source file. env is the construction environment (a dictionary of construction values) in force for this file installation.

INSTALLSTR
  The string displayed when a file is installed into a destination file name. The default is:

        Install file: "$SOURCE" as "$TARGET"

INTEL_C_COMPILER_VERSION
  Set by the "intelc" Tool to the major version number of the Intel C compiler selected for use.

JAR
  The Java archive tool.

JARCHDIR
  The directory to which the Java archive tool should change (using the -C option).

JARCOM
  The command line used to call the Java archive tool.

JARCOMSTR
  The string displayed when the Java archive tool is called If this is not set, then $JARCOM (the command line) is displayed.

        env = Environment(JARCOMSTR = "JARchiving $SOURCES into $TARGET")

JARFLAGS
  General options passed to the Java archive tool. By default this is set to cf to create the necessary jar file.

JARSUFFIX
  The suffix for Java archives: .jar by default.

JAVABOOTCLASSPATH
  Specifies the list of directories that will be added to the &javac; command line via the -bootclasspath option. The individual directory names will be separated by the operating system's path separate character (: on UNIX/Linux/POSIX, ; on Windows).

JAVAC
  The Java compiler.

JAVACCOM
  The command line used to compile a directory tree containing Java source files to corresponding Java class files. Any options specified in the $JAVACFLAGS construction variable are included on this command line.

JAVACCOMSTR
  The string displayed when compiling a directory tree of Java source files to corresponding Java class files. If this is not set, then $JAVACCOM (the command line) is displayed.

        env = Environment(JAVACCOMSTR = "Compiling class files $TARGETS from $SOURCES")

JAVACFLAGS
  General options that are passed to the Java compiler.

JAVACLASSDIR
  The directory in which Java class files may be found. This is stripped from the beginning of any Java .class file names supplied to the JavaH builder.

JAVACLASSPATH
  Specifies the list of directories that will be searched for Java .class file. The directories in this list will be added to the &javac; and &javah; command lines via the -classpath option. The individual directory names will be separated by the operating system's path separate character (: on UNIX/Linux/POSIX, ; on Windows).

  Note that this currently just adds the specified directory via the -classpath option. &SCons; does not currently search the $JAVACLASSPATH directories for dependency .class files.

JAVACLASSSUFFIX
  The suffix for Java class files; .class by default.

JAVAH
  The Java generator for C header and stub files.

JAVAHCOM
  The command line used to generate C header and stub files from Java classes. Any options specified in the $JAVAHFLAGS construction variable are included on this command line.

JAVAHCOMSTR
  The string displayed when C header and stub files are generated from Java classes. If this is not set, then $JAVAHCOM (the command line) is displayed.

        env = Environment(JAVAHCOMSTR = "Generating header/stub file(s) $TARGETS from $SOURCES")

JAVAHFLAGS
  General options passed to the C header and stub file generator for Java classes.

JAVASOURCEPATH
  Specifies the list of directories that will be searched for input .java file. The directories in this list will be added to the &javac; command line via the -sourcepath option. The individual directory names will be separated by the operating system's path separate character (: on UNIX/Linux/POSIX, ; on Windows).

  Note that this currently just adds the specified directory via the -sourcepath option. &SCons; does not currently search the $JAVASOURCEPATH directories for dependency .java files.

JAVASUFFIX
  The suffix for Java files; .java by default.

JAVAVERSION
  Specifies the Java version being used by the Java() builder. This is not currently used to select one version of the Java compiler vs. another. Instead, you should set this to specify the version of Java supported by your &javac; compiler. The default is 1.4.

  This is sometimes necessary because Java 1.5 changed the file names that are created for nested anonymous inner classes, which can cause a mismatch with the files that &SCons; expects will be generated by the &javac; compiler. Setting $JAVAVERSION to 1.5 (or 1.6, as appropriate) can make &SCons; realize that a Java 1.5 or 1.6 build is actually up to date.

LATEX
  The LaTeX structured formatter and typesetter.

LATEXCOM
  The command line used to call the LaTeX structured formatter and typesetter.

LATEXCOMSTR
  The string displayed when calling the LaTeX structured formatter and typesetter. If this is not set, then $LATEXCOM (the command line) is displayed.

        env = Environment(LATEXCOMSTR = "Building $TARGET from LaTeX input $SOURCES")

LATEXFLAGS
  General options passed to the LaTeX structured formatter and typesetter.

LATEXRETRIES
  The maximum number of times that LaTeX will be re-run if the .log generated by the $LATEXCOM command indicates that there are undefined references. The default is to try to resolve undefined references by re-running LaTeX up to three times.

LATEXSUFFIXES
  The list of suffixes of files that will be scanned for LaTeX implicit dependencies (\include or \import files). The default list is:

        [".tex", ".ltx", ".latex"]

LDMODULE
  The linker for building loadable modules. By default, this is the same as $SHLINK.

LDMODULECOM
  The command line for building loadable modules. On Mac OS X, this uses the $LDMODULE, $LDMODULEFLAGS and $FRAMEWORKSFLAGS variables. On other systems, this is the same as $SHLINK.

LDMODULECOMSTR
  The string displayed when building loadable modules. If this is not set, then $LDMODULECOM (the command line) is displayed.

LDMODULEFLAGS
  General user options passed to the linker for building loadable modules.

LDMODULEPREFIX
  The prefix used for loadable module file names. On Mac OS X, this is null; on other systems, this is the same as $SHLIBPREFIX.

LDMODULESUFFIX
  The suffix used for loadable module file names. On Mac OS X, this is null; on other systems, this is the same as $SHLIBSUFFIX.

LEX
  The lexical analyzer generator.

LEXCOM
  The command line used to call the lexical analyzer generator to generate a source file.

LEXCOMSTR
  The string displayed when generating a source file using the lexical analyzer generator. If this is not set, then $LEXCOM (the command line) is displayed.

        env = Environment(LEXCOMSTR = "Lex'ing $TARGET from $SOURCES")

LEXFLAGS
  General options passed to the lexical analyzer generator.

_LIBDIRFLAGS
  An automatically-generated construction variable containing the linker command-line options for specifying directories to be searched for library. The value of $_LIBDIRFLAGS is created by appending $LIBDIRPREFIX and $LIBDIRSUFFIX to the beginning and end of each directory in $LIBPATH.

LIBDIRPREFIX
  The prefix used to specify a library directory on the linker command line. This will be appended to the beginning of each directory in the $LIBPATH construction variable when the $_LIBDIRFLAGS variable is automatically generated.

LIBDIRSUFFIX
  The suffix used to specify a library directory on the linker command line. This will be appended to the end of each directory in the $LIBPATH construction variable when the $_LIBDIRFLAGS variable is automatically generated.

_LIBFLAGS
  An automatically-generated construction variable containing the linker command-line options for specifying libraries to be linked with the resulting target. The value of $_LIBFLAGS is created by appending $LIBLINKPREFIX and $LIBLINKSUFFIX to the beginning and end of each filename in $LIBS.

LIBLINKPREFIX
  The prefix used to specify a library to link on the linker command line. This will be appended to the beginning of each library in the $LIBS construction variable when the $_LIBFLAGS variable is automatically generated.

LIBLINKSUFFIX
  The suffix used to specify a library to link on the linker command line. This will be appended to the end of each library in the $LIBS construction variable when the $_LIBFLAGS variable is automatically generated.

LIBPATH
  The list of directories that will be searched for libraries. The implicit dependency scanner will search these directories for include files. Don't explicitly put include directory arguments in $LINKFLAGS or $SHLINKFLAGS because the result will be non-portable and the directories will not be searched by the dependency scanner. Note: directory names in LIBPATH will be looked-up relative to the SConscript directory when they are used in a command. To force scons to look-up a directory relative to the root of the source tree use #:

        env = Environment(LIBPATH='#/libs')

  The directory look-up can also be forced using the Dir() function:

        libs = Dir('libs')
        env = Environment(LIBPATH=libs)

  The directory list will be added to command lines through the automatically-generated $_LIBDIRFLAGS construction variable, which is constructed by appending the values of the $LIBDIRPREFIX and $LIBDIRSUFFIX construction variables to the beginning and end of each directory in $LIBPATH. Any command lines you define that need the LIBPATH directory list should include $_LIBDIRFLAGS:

        env = Environment(LINKCOM="my_linker $_LIBDIRFLAGS $_LIBFLAGS -o $TARGET $SOURCE")

LIBPREFIX
  The prefix used for (static) library file names. A default value is set for each platform (posix, win32, os2, etc.), but the value is overridden by individual tools (ar, mslib, sgiar, sunar, tlib, etc.) to reflect the names of the libraries they create.

LIBPREFIXES
  A list of all legal prefixes for library file names. When searching for library dependencies, SCons will look for files with these prefixes, the base library name, and suffixes in the $LIBSUFFIXES list.

LIBS
  A list of one or more libraries that will be linked with any executable programs created by this environment.

  The library list will be added to command lines through the automatically-generated $_LIBFLAGS construction variable, which is constructed by appending the values of the $LIBLINKPREFIX and $LIBLINKSUFFIX construction variables to the beginning and end of each filename in $LIBS. Any command lines you define that need the LIBS library list should include $_LIBFLAGS:

        env = Environment(LINKCOM="my_linker $_LIBDIRFLAGS $_LIBFLAGS -o $TARGET $SOURCE")

  If you add a File object to the $LIBS list, the name of that file will be added to $_LIBFLAGS, and thus the link line, as is, without $LIBLINKPREFIX or $LIBLINKSUFFIX. For example:

        env.Append(LIBS=File('/tmp/mylib.so'))

  In all cases, scons will add dependencies from the executable program to all the libraries in this list.

LIBSUFFIX
  The suffix used for (static) library file names. A default value is set for each platform (posix, win32, os2, etc.), but the value is overridden by individual tools (ar, mslib, sgiar, sunar, tlib, etc.) to reflect the names of the libraries they create.

LIBSUFFIXES
  A list of all legal suffixes for library file names. When searching for library dependencies, SCons will look for files with prefixes, in the $LIBPREFIXES list, the base library name, and these suffixes.

LICENSE
  The abbreviated name of the license under which this project is released (gpl, lpgl, bsd etc.). See http://www.opensource.org/licenses/alphabetical for a list of license names.

LINK
  The linker.

LINKCOM
  The command line used to link object files into an executable.

LINKCOMSTR
  The string displayed when object files are linked into an executable. If this is not set, then $LINKCOM (the command line) is displayed.

        env = Environment(LINKCOMSTR = "Linking $TARGET")

LINKFLAGS
  General user options passed to the linker. Note that this variable should not contain -l (or similar) options for linking with the libraries listed in $LIBS, nor -L (or similar) library search path options that scons generates automatically from $LIBPATH. See $_LIBFLAGS above, for the variable that expands to library-link options, and $_LIBDIRFLAGS above, for the variable that expands to library search path options.

M4
  The M4 macro preprocessor.

M4COM
  The command line used to pass files through the M4 macro preprocessor.

M4COMSTR
  The string displayed when a file is passed through the M4 macro preprocessor. If this is not set, then $M4COM (the command line) is displayed.

M4FLAGS
  General options passed to the M4 macro preprocessor.

MAKEINDEX
  The makeindex generator for the TeX formatter and typesetter and the LaTeX structured formatter and typesetter.

MAKEINDEXCOM
  The command line used to call the makeindex generator for the TeX formatter and typesetter and the LaTeX structured formatter and typesetter.

MAKEINDEXCOMSTR
  The string displayed when calling the makeindex generator for the TeX formatter and typesetter and the LaTeX structured formatter and typesetter. If this is not set, then $MAKEINDEXCOM (the command line) is displayed.

MAKEINDEXFLAGS
  General options passed to the makeindex generator for the TeX formatter and typesetter and the LaTeX structured formatter and typesetter.

MAXLINELENGTH
  The maximum number of characters allowed on an external command line. On Win32 systems, link lines longer than this many characters are linked via a temporary file name.

MIDL
  The Microsoft IDL compiler.

MIDLCOM
  The command line used to pass files to the Microsoft IDL compiler.

MIDLCOMSTR
  The string displayed when the Microsoft IDL copmiler is called. If this is not set, then $MIDLCOM (the command line) is displayed.

MIDLFLAGS
  General options passed to the Microsoft IDL compiler.

MSVS
  When the Microsoft Visual Studio tools are initialized, they set up this dictionary with the following keys:

  VERSION: the version of MSVS being used (can be set via MSVS_VERSION)

  VERSIONS: the available versions of MSVS installed

  VCINSTALLDIR: installed directory of Visual C++

  VSINSTALLDIR: installed directory of Visual Studio

  FRAMEWORKDIR: installed directory of the .NET framework

  FRAMEWORKVERSIONS: list of installed versions of the .NET framework, sorted latest to oldest.

  FRAMEWORKVERSION: latest installed version of the .NET framework

  FRAMEWORKSDKDIR: installed location of the .NET SDK.

  PLATFORMSDKDIR: installed location of the Platform SDK.

  PLATFORMSDK_MODULES: dictionary of installed Platform SDK modules, where the dictionary keys are keywords for the various modules, and the values are 2-tuples where the first is the release date, and the second is the version number.

  If a value isn't set, it wasn't available in the registry.

MSVS_IGNORE_IDE_PATHS
  Tells the MS Visual Studio tools to use minimal INCLUDE, LIB, and PATH settings, instead of the settings from the IDE.

  For Visual Studio, SCons will (by default) automatically determine where MSVS is installed, and use the LIB, INCLUDE, and PATH variables set by the IDE. You can override this behavior by setting these variables after Environment initialization, or by setting MSVS_IGNORE_IDE_PATHS = 1 in the Environment initialization. Specifying this will not leave these unset, but will set them to a minimal set of paths needed to run the tools successfully.

  For VS6, the mininimal set is:

           INCLUDE:'<VSDir>\VC98\ATL\include;<VSDir>\VC98\MFC\include;<VSDir>\VC98\include'
           LIB:'<VSDir>\VC98\MFC\lib;<VSDir>\VC98\lib'
           PATH:'<VSDir>\Common\MSDev98\bin;<VSDir>\VC98\bin'

  For VS7, it is:

           INCLUDE:'<VSDir>\Vc7\atlmfc\include;<VSDir>\Vc7\include'
           LIB:'<VSDir>\Vc7\atlmfc\lib;<VSDir>\Vc7\lib'
           PATH:'<VSDir>\Common7\Tools\bin;<VSDir>\Common7\Tools;<VSDir>\Vc7\bin'

  Where '<VSDir>' is the installed location of Visual Studio.

MSVS_PROJECT_BASE_PATH
  The string placed in a generated Microsoft Visual Studio solution file as the value of the SccProjectFilePathRelativizedFromConnection0 and SccProjectFilePathRelativizedFromConnection1 attributes of the GlobalSection(SourceCodeControl) section. There is no default value.

MSVS_PROJECT_GUID
  The string placed in a generated Microsoft Visual Studio project file as the value of the ProjectGUID attribute. The string is also placed in the SolutionUniqueID attribute of the GlobalSection(SourceCodeControl) section of the Microsoft Visual Studio solution file. There is no default value.

MSVS_SCC_AUX_PATH
  The path name placed in a generated Microsoft Visual Studio project file as the value of the SccAuxPath attribute if the MSVS_SCC_PROVIDER construction variable is also set. There is no default value.

MSVS_SCC_LOCAL_PATH
  The path name placed in a generated Microsoft Visual Studio project file as the value of the SccLocalPath attribute if the MSVS_SCC_PROVIDER construction variable is also set. The path name is also placed in the SccLocalPath0 and SccLocalPath1 attributes of the GlobalSection(SourceCodeControl) section of the Microsoft Visual Studio solution file. There is no default value.

MSVS_SCC_PROJECT_NAME
  The project name placed in a generated Microsoft Visual Studio project file as the value of the SccProjectName attribute. There is no default value.

MSVS_SCC_PROVIDER
  The string placed in a generated Microsoft Visual Studio project file as the value of the SccProvider attribute. The string is also placed in the SccProvider1 attribute of the GlobalSection(SourceCodeControl) section of the Microsoft Visual Studio solution file. There is no default value.

MSVS_USE_MFC_DIRS
  Tells the MS Visual Studio tool(s) to use the MFC directories in its default paths for compiling and linking. The $MSVS_USE_MFC_DIRS variable has no effect if the INCLUDE or LIB environment variables are set explictly.

  Under Visual Studio version 6, setting $MSVS_USE_MFC_DIRS to a non-zero value adds the ATL\\ATL and MFC\\MFC directories to the default INCLUDE external environment variable, and adds the MFC\\MFC directory to the default LIB external environment variable.

  Under Visual Studio version 7, setting $MSVS_USE_MFC_DIRS to a non-zero value adds the atlmfc\\atlmfc directory to the default INCLUDE external environment variable, and adds the atlmfc\\atlmfc directory to the default LIB external environment variable.

  Under Visual Studio version 8, setting $MSVS_USE_MFC_DIRS to a non-zero value will, by default, add the atlmfc\\atlmfc directory to the default INCLUDE external environment variable, and the atlmfc\\atlmfc directory to the default LIB external environment variable. If, however, the ['MSVS']['PLATFORMSDKDIR'] variable is set, then the mfc and the atl subdirectories of the PLATFORMSDKDIR are added to the default value of the INCLUDE external environment variable, and the default value of the LIB external environment variable is left untouched.

MSVS_VERSION
  Sets the preferred version of MSVS to use.

  SCons will (by default) select the latest version of MSVS installed on your machine. So, if you have version 6 and version 7 (MSVS .NET) installed, it will prefer version 7. You can override this by specifying the MSVS_VERSION variable in the Environment initialization, setting it to the appropriate version ('6.0' or '7.0', for example). If the given version isn't installed, tool initialization will fail.

MSVSBUILDCOM
  The build command line placed in a generated Microsoft Visual Studio project file. The default is to have Visual Studio invoke SCons with any specified build targets.

MSVSCLEANCOM
  The clean command line placed in a generated Microsoft Visual Studio project file. The default is to have Visual Studio invoke SCons with the -c option to remove any specified targets.

MSVSENCODING
  The encoding string placed in a generated Microsoft Visual Studio project file. The default is encoding Windows-1252.

MSVSPROJECTCOM
  The action used to generate Microsoft Visual Studio project files.

MSVSPROJECTSUFFIX
  The suffix used for Microsoft Visual Studio project (DSP) files. The default value is .vcproj when using Visual Studio version 7.x (.NET) or later version, and .dsp when using earlier versions of Visual Studio.

MSVSREBUILDCOM
  The rebuild command line placed in a generated Microsoft Visual Studio project file. The default is to have Visual Studio invoke SCons with any specified rebuild targets.

MSVSSCONS
  The SCons used in generated Microsoft Visual Studio project files. The default is the version of SCons being used to generate the project file.

MSVSSCONSCOM
  The default SCons command used in generated Microsoft Visual Studio project files.

MSVSSCONSCRIPT
  The sconscript file (that is, SConstruct or SConscript file) that will be invoked by Visual Studio project files (through the $MSVSSCONSCOM variable). The default is the same sconscript file that contains the call to MSVSProject() to build the project file.

MSVSSCONSFLAGS
  The SCons flags used in generated Microsoft Visual Studio project files.

MSVSSOLUTIONCOM
  The action used to generate Microsoft Visual Studio solution files.

MSVSSOLUTIONSUFFIX
  The suffix used for Microsoft Visual Studio solution (DSW) files. The default value is .sln when using Visual Studio version 7.x (.NET), and .dsw when using earlier versions of Visual Studio.

MWCW_VERSION
  The version number of the MetroWerks CodeWarrior C compiler to be used.

MWCW_VERSIONS
  A list of installed versions of the MetroWerks CodeWarrior C compiler on this system.

NAME
  Specfies the name of the project to package.

no_import_lib
  When set to non-zero, suppresses creation of a corresponding Windows static import lib by the SharedLibrary builder when used with MinGW, Microsoft Visual Studio or Metrowerks. This also suppresses creation of an export (.exp) file when using Microsoft Visual Studio.

OBJPREFIX
  The prefix used for (static) object file names.

OBJSUFFIX
  The suffix used for (static) object file names.

P4
  The Perforce executable.

P4COM
  The command line used to fetch source files from Perforce.

P4COMSTR
  The string displayed when fetching a source file from Perforce. If this is not set, then $P4COM (the command line) is displayed.

P4FLAGS
  General options that are passed to Perforce.

PACKAGEROOT
  Specifies the directory where all files in resulting archive will be placed if applicable. The default value is "$NAME-$VERSION".

PACKAGETYPE
  Selects the package type to build. Currently these are available:

  * msi - Microsoft Installer
  * rpm - Redhat Package Manger
  * ipkg - Itsy Package Management System
  * tarbz2 - compressed tar
  * targz - compressed tar
  * zip - zip file
  * src_tarbz2 - compressed tar source
  * src_targz - compressed tar source
  * src_zip - zip file source

  This may be overridden with the "package_type" command line option.

PACKAGEVERSION
  The version of the package (not the underlying project). This is currently only used by the rpm packager and should reflect changes in the packaging, not the underlying project code itself.

PCH
  The Microsoft Visual C++ precompiled header that will be used when compiling object files. This variable is ignored by tools other than Microsoft Visual C++. When this variable is defined SCons will add options to the compiler command line to cause it to use the precompiled header, and will also set up the dependencies for the PCH file. Example:

        env['PCH'] = 'StdAfx.pch'

PCHCOM
  The command line used by the PCH() builder to generated a precompiled header.

PCHCOMSTR
  The string displayed when generating a precompiled header. If this is not set, then $PCHCOM (the command line) is displayed.

PCHPDBFLAGS
  A construction variable that, when expanded, adds the /yD flag to the command line only if the $PDB construction variable is set.

PCHSTOP
  This variable specifies how much of a source file is precompiled. This variable is ignored by tools other than Microsoft Visual C++, or when the PCH variable is not being used. When this variable is define it must be a string that is the name of the header that is included at the end of the precompiled portion of the source files, or the empty string if the "#pragma hrdstop" construct is being used:

        env['PCHSTOP'] = 'StdAfx.h'

PDB
  The Microsoft Visual C++ PDB file that will store debugging information for object files, shared libraries, and programs. This variable is ignored by tools other than Microsoft Visual C++. When this variable is defined SCons will add options to the compiler and linker command line to cause them to generate external debugging information, and will also set up the dependencies for the PDB file. Example:

        env['PDB'] = 'hello.pdb'

  The Visual C++ compiler switch that SCons uses by default to generate PDB information is /Z7. This works correctly with parallel (-j) builds because it embeds the debug information in the intermediate object files, as opposed to sharing a single PDB file between multiple object files. This is also the only way to get debug information embedded into a static library. Using the /Zi instead may yield improved link-time performance, although parallel builds will no longer work. You can generate PDB files with the /Zi switch by overriding the default $CCPDBFLAGS variable; see the entry for that variable for specific examples.

PDFCOM
  A deprecated synonym for $DVIPDFCOM.

PDFLATEX
  The &pdflatex; utility.

PDFLATEXCOM
  The command line used to call the &pdflatex; utility.

PDFLATEXCOMSTR
  The string displayed when calling the &pdflatex; utility. If this is not set, then $PDFLATEXCOM (the command line) is displayed.

        env = Environment(PDFLATEX;COMSTR = "Building $TARGET from LaTeX input $SOURCES")

PDFLATEXFLAGS
  General options passed to the &pdflatex; utility.

PDFPREFIX
  The prefix used for PDF file names.

PDFSUFFIX
  The suffix used for PDF file names.

PDFTEX
  The &pdftex; utility.

PDFTEXCOM
  The command line used to call the &pdftex; utility.

PDFTEXCOMSTR
  The string displayed when calling the &pdftex; utility. If this is not set, then $PDFTEXCOM (the command line) is displayed.

        env = Environment(PDFTEXCOMSTR = "Building $TARGET from TeX input $SOURCES")

PDFTEXFLAGS
  General options passed to the &pdftex; utility.

PKGCHK
  On Solaris systems, the package-checking program that will be used (along with $PKGINFO) to look for installed versions of the Sun PRO C++ compiler. The default is /usr/sbin/pgkchk.

PKGINFO
  On Solaris systems, the package information program that will be used (along with $PKGCHK) to look for installed versions of the Sun PRO C++ compiler. The default is pkginfo.

PLATFORM
  The name of the platform used to create the Environment. If no platform is specified when the Environment is created, scons autodetects the platform.

        env = Environment(tools = [])
        if env['PLATFORM'] == 'cygwin':
            Tool('mingw')(env)
        else:
            Tool('msvc')(env)

PRINT_CMD_LINE_FUNC
  A Python function used to print the command lines as they are executed (assuming command printing is not disabled by the -q or -s options or their equivalents). The function should take four arguments: s, the command being executed (a string), target, the target being built (file node, list, or string name(s)), source, the source(s) used (file node, list, or string name(s)), and env, the environment being used.

  The function must do the printing itself. The default implementation, used if this variable is not set or is None, is:

        def print_cmd_line(s, target, source, env):
          sys.stdout.write(s + "\n")

  Here's an example of a more interesting function:

        def print_cmd_line(s, target, source, env):
           sys.stdout.write("Building %s -> %s...\n" %
            (' and '.join([str(x) for x in source]),
             ' and '.join([str(x) for x in target])))
        env=Environment(PRINT_CMD_LINE_FUNC=print_cmd_line)
        env.Program('foo', 'foo.c')

  This just prints "Building targetname from sourcename..." instead of the actual commands. Such a function could also log the actual commands to a log file, for example.

PROGPREFIX
  The prefix used for executable file names.

PROGSUFFIX
  The suffix used for executable file names.

PSCOM
  The command line used to convert TeX DVI files into a PostScript file.

PSCOMSTR
  The string displayed when a TeX DVI file is converted into a PostScript file. If this is not set, then $PSCOM (the command line) is displayed.

PSPREFIX
  The prefix used for PostScript file names.

PSSUFFIX
  The prefix used for PostScript file names.

QT_AUTOSCAN
  Turn off scanning for mocable files. Use the Moc Builder to explicitely specify files to run moc on.

QT_BINPATH
  The path where the qt binaries are installed. The default value is '$QTDIR/bin'.

QT_CPPPATH
  The path where the qt header files are installed. The default value is '$QTDIR/include'. Note: If you set this variable to None, the tool won't change the $CPPPATH construction variable.

QT_DEBUG
  Prints lots of debugging information while scanning for moc files.

QT_LIB
  Default value is 'qt'. You may want to set this to 'qt-mt'. Note: If you set this variable to None, the tool won't change the $LIBS variable.

QT_LIBPATH
  The path where the qt libraries are installed. The default value is '$QTDIR/lib'. Note: If you set this variable to None, the tool won't change the $LIBPATH construction variable.

QT_MOC
  Default value is '$QT_BINPATH/moc'.

QT_MOCCXXPREFIX
  Default value is ''. Prefix for moc output files, when source is a cxx file.

QT_MOCCXXSUFFIX
  Default value is '.moc'. Suffix for moc output files, when source is a cxx file.

QT_MOCFROMCXXCOM
  Command to generate a moc file from a cpp file.

QT_MOCFROMCXXCOMSTR
  The string displayed when generating a moc file from a cpp file. If this is not set, then $QT_MOCFROMCXXCOM (the command line) is displayed.

QT_MOCFROMCXXFLAGS
  Default value is '-i'. These flags are passed to moc, when moccing a C++ file.

QT_MOCFROMHCOM
  Command to generate a moc file from a header.

QT_MOCFROMHCOMSTR
  The string displayed when generating a moc file from a cpp file. If this is not set, then $QT_MOCFROMHCOM (the command line) is displayed.

QT_MOCFROMHFLAGS
  Default value is ''. These flags are passed to moc, when moccing a header file.

QT_MOCHPREFIX
  Default value is 'moc_'. Prefix for moc output files, when source is a header.

QT_MOCHSUFFIX
  Default value is '$CXXFILESUFFIX'. Suffix for moc output files, when source is a header.

QT_UIC
  Default value is '$QT_BINPATH/uic'.

QT_UICCOM
  Command to generate header files from .ui files.

QT_UICCOMSTR
  The string displayed when generating header files from .ui files. If this is not set, then $QT_UICCOM (the command line) is displayed.

QT_UICDECLFLAGS
  Default value is ''. These flags are passed to uic, when creating a a h file from a .ui file.

QT_UICDECLPREFIX
  Default value is ''. Prefix for uic generated header files.

QT_UICDECLSUFFIX
  Default value is '.h'. Suffix for uic generated header files.

QT_UICIMPLFLAGS
  Default value is ''. These flags are passed to uic, when creating a cxx file from a .ui file.

QT_UICIMPLPREFIX
  Default value is 'uic_'. Prefix for uic generated implementation files.

QT_UICIMPLSUFFIX
  Default value is '$CXXFILESUFFIX'. Suffix for uic generated implementation files.

QT_UISUFFIX
  Default value is '.ui'. Suffix of designer input files.

QTDIR
  The qt tool tries to take this from os.environ. It also initializes all QT_* construction variables listed below. (Note that all paths are constructed with python's os.path.join() method, but are listed here with the '/' separator for easier reading.) In addition, the construction environment variables $CPPPATH, $LIBPATH and $LIBS may be modified and the variables PROGEMITTER, SHLIBEMITTER and LIBEMITTER are modified. Because the build-performance is affected when using this tool, you have to explicitly specify it at Environment creation:

        Environment(tools=['default','qt'])

  The qt tool supports the following operations:

  Automatic moc file generation from header files. You do not have to specify moc files explicitly, the tool does it for you. However, there are a few preconditions to do so: Your header file must have the same filebase as your implementation file and must stay in the same directory. It must have one of the suffixes .h, .hpp, .H, .hxx, .hh. You can turn off automatic moc file generation by setting QT_AUTOSCAN to 0. See also the corresponding builder method Moc()

  Automatic moc file generation from cxx files. As stated in the qt documentation, include the moc file at the end of the cxx file. Note that you have to include the file, which is generated by the transformation ${QT_MOCCXXPREFIX}<basename>${QT_MOCCXXSUFFIX}, by default <basename>.moc. A warning is generated after building the moc file, if you do not include the correct file. If you are using VariantDir, you may need to specify duplicate=1. You can turn off automatic moc file generation by setting QT_AUTOSCAN to 0. See also the corresponding Moc() builder method.

  Automatic handling of .ui files. The implementation files generated from .ui files are handled much the same as yacc or lex files. Each .ui file given as a source of Program, Library or SharedLibrary will generate three files, the declaration file, the implementation file and a moc file. Because there are also generated headers, you may need to specify duplicate=1 in calls to VariantDir. See also the corresponding Uic() builder method.

RANLIB
  The archive indexer.

RANLIBCOM
  The command line used to index a static library archive.

RANLIBCOMSTR
  The string displayed when a static library archive is indexed. If this is not set, then $RANLIBCOM (the command line) is displayed.

        env = Environment(RANLIBCOMSTR = "Indexing $TARGET")

RANLIBFLAGS
  General options passed to the archive indexer.

RC
  The resource compiler used to build a Microsoft Visual C++ resource file.

RCCOM
  The command line used to build a Microsoft Visual C++ resource file.

RCCOMSTR
  The string displayed when invoking the resource compiler to build a Microsoft Visual C++ resource file. If this is not set, then $RCCOM (the command line) is displayed.

RCFLAGS
  The flags passed to the resource compiler by the RES builder.

RCINCFLAGS
  An automatically-generated construction variable containing the command-line options for specifying directories to be searched by the resource compiler. The value of $RCINCFLAGS is created by appending $RCINCPREFIX and $RCINCSUFFIX to the beginning and end of each directory in $CPPPATH.

RCINCPREFIX
  The prefix (flag) used to specify an include directory on the resource compiler command line. This will be appended to the beginning of each directory in the $CPPPATH construction variable when the $RCINCFLAGS variable is expanded.

RCINCSUFFIX
  The suffix used to specify an include directory on the resource compiler command line. This will be appended to the end of each directory in the $CPPPATH construction variable when the $RCINCFLAGS variable is expanded.

RCS
  The RCS executable. Note that this variable is not actually used for the command to fetch source files from RCS; see the $RCS_CO construction variable, below.

RCS_CO
  The RCS "checkout" executable, used to fetch source files from RCS.

RCS_COCOM
  The command line used to fetch (checkout) source files from RCS.

RCS_COCOMSTR
  The string displayed when fetching a source file from RCS. If this is not set, then $RCS_COCOM (the command line) is displayed.

RCS_COFLAGS
  Options that are passed to the $RCS_CO command.

RDirs
  A function that converts a string into a list of Dir instances by searching the repositories.

REGSVR
  The program used on Windows systems to register a newly-built DLL library whenever the SharedLibrary() builder is passed a keyword argument of register=1.

REGSVRCOM
  The command line used on Windows systems to register a newly-built DLL library whenever the SharedLibrary() builder is passed a keyword argument of register=1.

REGSVRCOMSTR
  The string displayed when registering a newly-built DLL file. If this is not set, then $REGSVRCOM (the command line) is displayed.

REGSVRFLAGS
  Flags passed to the DLL registration program on Windows systems when a newly-built DLL library is registered. By default, this includes the /s that prevents dialog boxes from popping up and requiring user attention.

RMIC
  The Java RMI stub compiler.

RMICCOM
  The command line used to compile stub and skeleton class files from Java classes that contain RMI implementations. Any options specified in the $RMICFLAGS construction variable are included on this command line.

RMICCOMSTR
  The string displayed when compiling stub and skeleton class files from Java classes that contain RMI implementations. If this is not set, then $RMICCOM (the command line) is displayed.

        env = Environment(RMICCOMSTR = "Generating stub/skeleton class files $TARGETS from $SOURCES")

RMICFLAGS
  General options passed to the Java RMI stub compiler.

_RPATH
  An automatically-generated construction variable containing the rpath flags to be used when linking a program with shared libraries. The value of $_RPATH is created by appending $RPATHPREFIX and $RPATHSUFFIX to the beginning and end of each directory in $RPATH.

RPATH
  A list of paths to search for shared libraries when running programs. Currently only used in the GNU (gnulink), IRIX (sgilink) and Sun (sunlink) linkers. Ignored on platforms and toolchains that don't support it. Note that the paths added to RPATH are not transformed by scons in any way: if you want an absolute path, you must make it absolute yourself.

RPATHPREFIX
  The prefix used to specify a directory to be searched for shared libraries when running programs. This will be appended to the beginning of each directory in the $RPATH construction variable when the $_RPATH variable is automatically generated.

RPATHSUFFIX
  The suffix used to specify a directory to be searched for shared libraries when running programs. This will be appended to the end of each directory in the $RPATH construction variable when the $_RPATH variable is automatically generated.

RPCGEN
  The RPC protocol compiler.

RPCGENCLIENTFLAGS
  Options passed to the RPC protocol compiler when generating client side stubs. These are in addition to any flags specified in the $RPCGENFLAGS construction variable.

RPCGENFLAGS
  General options passed to the RPC protocol compiler.

RPCGENHEADERFLAGS
  Options passed to the RPC protocol compiler when generating a header file. These are in addition to any flags specified in the $RPCGENFLAGS construction variable.

RPCGENSERVICEFLAGS
  Options passed to the RPC protocol compiler when generating server side stubs. These are in addition to any flags specified in the $RPCGENFLAGS construction variable.

RPCGENXDRFLAGS
  Options passed to the RPC protocol compiler when generating XDR routines. These are in addition to any flags specified in the $RPCGENFLAGS construction variable.

SCANNERS
  A list of the available implicit dependency scanners. New file scanners may be added by appending to this list, although the more flexible approach is to associate scanners with a specific Builder. See the sections "Builder Objects" and "Scanner Objects," below, for more information.

SCCS
  The SCCS executable.

SCCSCOM
  The command line used to fetch source files from SCCS.

SCCSCOMSTR
  The string displayed when fetching a source file from a CVS repository. If this is not set, then $SCCSCOM (the command line) is displayed.

SCCSFLAGS
  General options that are passed to SCCS.

SCCSGETFLAGS
  Options that are passed specifically to the SCCS "get" subcommand. This can be set, for example, to -e to check out editable files from SCCS.

SCONS_HOME
  The (optional) path to the SCons library directory, initialized from the external environment. If set, this is used to construct a shorter and more efficient search path in the $MSVSSCONS command line executed from Microsoft Visual Studio project files.

SHCC
  The C compiler used for generating shared-library objects.

SHCCCOM
  The command line used to compile a C source file to a shared-library object file. Any options specified in the $SHCFLAGS, $SHCCFLAGS and $CPPFLAGS construction variables are included on this command line.

SHCCCOMSTR
  The string displayed when a C source file is compiled to a shared object file. If this is not set, then $SHCCCOM (the command line) is displayed.

        env = Environment(SHCCCOMSTR = "Compiling shared object $TARGET")

SHCCFLAGS
  Options that are passed to the C and C++ compilers to generate shared-library objects.

SHCFLAGS
  Options that are passed to the C compiler (only; not C++) to generate shared-library objects.

SHCXX
  The C++ compiler used for generating shared-library objects.

SHCXXCOM
  The command line used to compile a C++ source file to a shared-library object file. Any options specified in the $SHCXXFLAGS and $CPPFLAGS construction variables are included on this command line.

SHCXXCOMSTR
  The string displayed when a C++ source file is compiled to a shared object file. If this is not set, then $SHCXXCOM (the command line) is displayed.

        env = Environment(SHCXXCOMSTR = "Compiling shared object $TARGET")

SHCXXFLAGS
  Options that are passed to the C++ compiler to generate shared-library objects.

SHELL
  A string naming the shell program that will be passed to the $SPAWN function. See the $SPAWN construction variable for more information.

SHF77
  The Fortran 77 compiler used for generating shared-library objects. You should normally set the $SHFORTRAN variable, which specifies the default Fortran compiler for all Fortran versions. You only need to set $SHF77 if you need to use a specific compiler or compiler version for Fortran 77 files.

SHF77COM
  The command line used to compile a Fortran 77 source file to a shared-library object file. You only need to set $SHF77COM if you need to use a specific command line for Fortran 77 files. You should normally set the $SHFORTRANCOM variable, which specifies the default command line for all Fortran versions.

SHF77COMSTR
  The string displayed when a Fortran 77 source file is compiled to a shared-library object file. If this is not set, then $SHF77COM or $SHFORTRANCOM (the command line) is displayed.

SHF77FLAGS
  Options that are passed to the Fortran 77 compiler to generated shared-library objects. You only need to set $SHF77FLAGS if you need to define specific user options for Fortran 77 files. You should normally set the $SHFORTRANFLAGS variable, which specifies the user-specified options passed to the default Fortran compiler for all Fortran versions.

SHF77PPCOM
  The command line used to compile a Fortran 77 source file to a shared-library object file after first running the file through the C preprocessor. Any options specified in the $SHF77FLAGS and $CPPFLAGS construction variables are included on this command line. You only need to set $SHF77PPCOM if you need to use a specific C-preprocessor command line for Fortran 77 files. You should normally set the $SHFORTRANPPCOM variable, which specifies the default C-preprocessor command line for all Fortran versions.

SHF77PPCOMSTR
  The string displayed when a Fortran 77 source file is compiled to a shared-library object file after first running the file through the C preprocessor. If this is not set, then $SHF77PPCOM or $SHFORTRANPPCOM (the command line) is displayed.

SHF90
  The Fortran 90 compiler used for generating shared-library objects. You should normally set the $SHFORTRAN variable, which specifies the default Fortran compiler for all Fortran versions. You only need to set $SHF90 if you need to use a specific compiler or compiler version for Fortran 90 files.

SHF90COM
  The command line used to compile a Fortran 90 source file to a shared-library object file. You only need to set $SHF90COM if you need to use a specific command line for Fortran 90 files. You should normally set the $SHFORTRANCOM variable, which specifies the default command line for all Fortran versions.

SHF90COMSTR
  The string displayed when a Fortran 90 source file is compiled to a shared-library object file. If this is not set, then $SHF90COM or $SHFORTRANCOM (the command line) is displayed.

SHF90FLAGS
  Options that are passed to the Fortran 90 compiler to generated shared-library objects. You only need to set $SHF90FLAGS if you need to define specific user options for Fortran 90 files. You should normally set the $SHFORTRANFLAGS variable, which specifies the user-specified options passed to the default Fortran compiler for all Fortran versions.

SHF90PPCOM
  The command line used to compile a Fortran 90 source file to a shared-library object file after first running the file through the C preprocessor. Any options specified in the $SHF90FLAGS and $CPPFLAGS construction variables are included on this command line. You only need to set $SHF90PPCOM if you need to use a specific C-preprocessor command line for Fortran 90 files. You should normally set the $SHFORTRANPPCOM variable, which specifies the default C-preprocessor command line for all Fortran versions.

SHF90PPCOMSTR
  The string displayed when a Fortran 90 source file is compiled to a shared-library object file after first running the file through the C preprocessor. If this is not set, then $SHF90PPCOM or $SHFORTRANPPCOM (the command line) is displayed.

SHF95
  The Fortran 95 compiler used for generating shared-library objects. You should normally set the $SHFORTRAN variable, which specifies the default Fortran compiler for all Fortran versions. You only need to set $SHF95 if you need to use a specific compiler or compiler version for Fortran 95 files.

SHF95COM
  The command line used to compile a Fortran 95 source file to a shared-library object file. You only need to set $SHF95COM if you need to use a specific command line for Fortran 95 files. You should normally set the $SHFORTRANCOM variable, which specifies the default command line for all Fortran versions.

SHF95COMSTR
  The string displayed when a Fortran 95 source file is compiled to a shared-library object file. If this is not set, then $SHF95COM or $SHFORTRANCOM (the command line) is displayed.

SHF95FLAGS
  Options that are passed to the Fortran 95 compiler to generated shared-library objects. You only need to set $SHF95FLAGS if you need to define specific user options for Fortran 95 files. You should normally set the $SHFORTRANFLAGS variable, which specifies the user-specified options passed to the default Fortran compiler for all Fortran versions.

SHF95PPCOM
  The command line used to compile a Fortran 95 source file to a shared-library object file after first running the file through the C preprocessor. Any options specified in the $SHF95FLAGS and $CPPFLAGS construction variables are included on this command line. You only need to set $SHF95PPCOM if you need to use a specific C-preprocessor command line for Fortran 95 files. You should normally set the $SHFORTRANPPCOM variable, which specifies the default C-preprocessor command line for all Fortran versions.

SHF95PPCOMSTR
  The string displayed when a Fortran 95 source file is compiled to a shared-library object file after first running the file through the C preprocessor. If this is not set, then $SHF95PPCOM or $SHFORTRANPPCOM (the command line) is displayed.

SHFORTRAN
  The default Fortran compiler used for generating shared-library objects.

SHFORTRANCOM
  The command line used to compile a Fortran source file to a shared-library object file.

SHFORTRANCOMSTR
  The string displayed when a Fortran source file is compiled to a shared-library object file. If this is not set, then $SHFORTRANCOM (the command line) is displayed.

SHFORTRANFLAGS
  Options that are passed to the Fortran compiler to generate shared-library objects.

SHFORTRANPPCOM
  The command line used to compile a Fortran source file to a shared-library object file after first running the file through the C preprocessor. Any options specified in the $SHFORTRANFLAGS and $CPPFLAGS construction variables are included on this command line.

SHFORTRANPPCOMSTR
  The string displayed when a Fortran source file is compiled to a shared-library object file after first running the file throught the C preprocessor. If this is not set, then $SHFORTRANPPCOM (the command line) is displayed.

SHLIBPREFIX
  The prefix used for shared library file names.

SHLIBSUFFIX
  The suffix used for shared library file names.

SHLINK
  The linker for programs that use shared libraries.

SHLINKCOM
  The command line used to link programs using shared libaries.

SHLINKCOMSTR
  The string displayed when programs using shared libraries are linked. If this is not set, then $SHLINKCOM (the command line) is displayed.

        env = Environment(SHLINKCOMSTR = "Linking shared $TARGET")

SHLINKFLAGS
  General user options passed to the linker for programs using shared libraries. Note that this variable should not contain -l (or similar) options for linking with the libraries listed in $LIBS, nor -L (or similar) include search path options that scons generates automatically from $LIBPATH. See $_LIBFLAGS above, for the variable that expands to library-link options, and $_LIBDIRFLAGS above, for the variable that expands to library search path options.

SHOBJPREFIX
  The prefix used for shared object file names.

SHOBJSUFFIX
  The suffix used for shared object file names.

SOURCE
  A reserved variable name that may not be set or used in a construction environment. (See "Variable Substitution," below.)

SOURCE_URL
  The URL (web address) of the location from which the project was retrieved. This is used to fill in the Source: field in the controlling information for Ipkg and RPM packages.

SOURCES
  A reserved variable name that may not be set or used in a construction environment. (See "Variable Substitution," below.)

SPAWN
  A command interpreter function that will be called to execute command line strings. The function must expect the following arguments:

        def spawn(shell, escape, cmd, args, env):

  sh is a string naming the shell program to use. escape is a function that can be called to escape shell special characters in the command line. cmd is the path to the command to be executed. args is the arguments to the command. env is a dictionary of the environment variables in which the command should be executed.

SUMMARY
  A short summary of what the project is about. This is used to fill in the Summary: field in the controlling information for Ipkg and RPM packages, and as the Description: field in MSI packages.

SWIG
  The scripting language wrapper and interface generator.

SWIGCFILESUFFIX
  The suffix that will be used for intermediate C source files generated by the scripting language wrapper and interface generator. The default value is _wrap$CFILESUFFIX. By default, this value is used whenever the -c++ option is not specified as part of the $SWIGFLAGS construction variable.

SWIGCOM
  The command line used to call the scripting language wrapper and interface generator.

SWIGCOMSTR
  The string displayed when calling the scripting language wrapper and interface generator. If this is not set, then $SWIGCOM (the command line) is displayed.

SWIGCXXFILESUFFIX
  The suffix that will be used for intermediate C++ source files generated by the scripting language wrapper and interface generator. The default value is _wrap$CFILESUFFIX. By default, this value is used whenever the -c++ option is specified as part of the $SWIGFLAGS construction variable.

SWIGFLAGS
  General options passed to the scripting language wrapper and interface generator. This is where you should set -python, -perl5, -tcl, or whatever other options you want to specify to SWIG. If you set the -c++ option in this variable, scons will, by default, generate a C++ intermediate source file with the extension that is specified as the $CXXFILESUFFIX variable.

_SWIGINCFLAGS
  An automatically-generated construction variable containing the SWIG command-line options for specifying directories to be searched for included files. The value of $_SWIGINCFLAGS is created by appending $SWIGINCPREFIX and $SWIGINCSUFFIX to the beginning and end of each directory in $SWIGPATH.

SWIGINCPREFIX
  The prefix used to specify an include directory on the SWIG command line. This will be appended to the beginning of each directory in the $SWIGPATH construction variable when the $_SWIGINCFLAGS variable is automatically generated.

SWIGINCSUFFIX
  The suffix used to specify an include directory on the SWIG command line. This will be appended to the end of each directory in the $SWIGPATH construction variable when the $_SWIGINCFLAGS variable is automatically generated.

SWIGOUTDIR
  Specifies the output directory in which the scripting language wrapper and interface generator should place generated language-specific files. This will be used by SCons to identify the files that will be generated by the &swig; call, and translated into the swig -outdir option on the command line.

SWIGPATH
  The list of directories that the scripting language wrapper and interface generate will search for included files. The SWIG implicit dependency scanner will search these directories for include files. The default is to use the same path specified as $CPPPATH.

  Don't explicitly put include directory arguments in SWIGFLAGS; the result will be non-portable and the directories will not be searched by the dependency scanner. Note: directory names in SWIGPATH will be looked-up relative to the SConscript directory when they are used in a command. To force scons to look-up a directory relative to the root of the source tree use #:

        env = Environment(SWIGPATH='#/include')

  The directory look-up can also be forced using the Dir() function:

        include = Dir('include')
        env = Environment(SWIGPATH=include)

  The directory list will be added to command lines through the automatically-generated $_SWIGINCFLAGS construction variable, which is constructed by appending the values of the $SWIGINCPREFIX and $SWIGINCSUFFIX construction variables to the beginning and end of each directory in $SWIGPATH. Any command lines you define that need the SWIGPATH directory list should include $_SWIGINCFLAGS:

        env = Environment(SWIGCOM="my_swig -o $TARGET $_SWIGINCFLAGS $SORUCES")

TAR
  The tar archiver.

TARCOM
  The command line used to call the tar archiver.

TARCOMSTR
  The string displayed when archiving files using the tar archiver. If this is not set, then $TARCOM (the command line) is displayed.

        env = Environment(TARCOMSTR = "Archiving $TARGET")

TARFLAGS
  General options passed to the tar archiver.

TARGET
  A reserved variable name that may not be set or used in a construction environment. (See "Variable Substitution," below.)

TARGETS
  A reserved variable name that may not be set or used in a construction environment. (See "Variable Substitution," below.)

TARSUFFIX
  The suffix used for tar file names.

TEMPFILEPREFIX
  The prefix for a temporary file used to execute lines longer than $MAXLINELENGTH. The default is '@'. This may be set for toolchains that use other values, such as '-@' for the diab compiler or '-via' for ARM toolchain.

TEX
  The TeX formatter and typesetter.

TEXCOM
  The command line used to call the TeX formatter and typesetter.

TEXCOMSTR
  The string displayed when calling the TeX formatter and typesetter. If this is not set, then $TEXCOM (the command line) is displayed.

        env = Environment(TEXCOMSTR = "Building $TARGET from TeX input $SOURCES")

TEXFLAGS
  General options passed to the TeX formatter and typesetter.

TEXINPUTS
  List of directories that the LaTeX programm will search for include directories. The LaTeX implicit dependency scanner will search these directories for \include and \import files.

TOOLS
  A list of the names of the Tool specifications that are part of this construction environment.

VENDOR
  The person or organization who supply the packaged software. This is used to fill in the Vendor: field in the controlling information for RPM packages, and the Manufacturer: field in the controlling information for MSI packages.

VERSION
  The version of the project, specified as a string.

WIN32_INSERT_DEF
  A deprecated synonym for $WINDOWS_INSERT_DEF.

WIN32DEFPREFIX
  A deprecated synonym for $WINDOWSDEFPREFIX.

WIN32DEFSUFFIX
  A deprecated synonym for $WINDOWSDEFSUFFIX.

WIN32EXPPREFIX
  A deprecated synonym for $WINDOWSEXPSUFFIX.

WIN32EXPSUFFIX
  A deprecated synonym for $WINDOWSEXPSUFFIX.

WINDOWS_INSERT_DEF
  When this is set to true, a library build of a Windows shared library (.dllfile) will also build a corresponding .def file at the same time, if a .def file is not already listed as a build target. The default is 0 (do not build a .def file).

WINDOWS_INSERT_MANIFEST
  When this is set to true, scons will be aware of the .manifest files generated by Microsoft Visua C/C++ 8.

WINDOWSDEFPREFIX
  The prefix used for Windows .deffile names.

WINDOWSDEFSUFFIX
  The suffix used for Windows .def file names.

WINDOWSEXPPREFIX
  The prefix used for Windows .exp file names.

WINDOWSEXPSUFFIX
  The suffix used for Windows .exp file names.

WINDOWSPROGMANIFESTPREFIX
  The prefix used for executable program .manifest files generated by Microsoft Visual C/C++.

WINDOWSPROGMANIFESTSUFFIX
  The suffix used for executable program .manifest files generated by Microsoft Visual C/C++.

WINDOWSSHLIBMANIFESTPREFIX
  The prefix used for shared library .manifest files generated by Microsoft Visual C/C++.

WINDOWSSHLIBMANIFESTSUFFIX
  The suffix used for shared library .manifest files generated by Microsoft Visual C/C++.

X_IPK_DEPENDS
  This is used to fill in the Depends: field in the controlling information for Ipkg packages.

X_IPK_DESCRIPTION
  This is used to fill in the Description: field in the controlling information for Ipkg packages. The default value is $SUMMARY\\$SUMMARY
X_IPK_MAINTAINER
  This is used to fill in the Maintainer: field in the controlling information for Ipkg packages.

X_IPK_PRIORITY
  This is used to fill in the Priority: field in the controlling information for Ipkg packages.

X_IPK_SECTION
  This is used to fill in the Section: field in the controlling information for Ipkg packages.

X_MSI_LANGUAGE
  This is used to fill in the Language: attribute in the controlling information for MSI packages.

X_MSI_LICENSE_TEXT
  The text of the software license in RTF format. Carriage return characters will be replaced with the RTF equivalent \
  ar.

X_MSI_UPGRADE_CODE
  TODO

X_RPM_AUTOREQPROV
  This is used to fill in the AutoReqProv: field in the RPM .spec file.

X_RPM_BUILD
  internal, but overridable

X_RPM_BUILDREQUIRES
  This is used to fill in the BuildRequires: field in the RPM .spec file.

X_RPM_BUILDROOT
  internal, but overridable

X_RPM_CLEAN
  internal, but overridable

X_RPM_CONFLICTS
  This is used to fill in the Conflicts: field in the RPM .spec file.

X_RPM_DEFATTR
  This value is used as the default attributes for the files in the RPM package. The default value is (-,root,root).

X_RPM_DISTRIBUTION
  This is used to fill in the Distribution: field in the RPM .spec file.

X_RPM_EPOCH
  This is used to fill in the Epoch: field in the controlling information for RPM packages.

X_RPM_EXCLUDEARCH
  This is used to fill in the ExcludeArch: field in the RPM .spec file.

X_RPM_EXLUSIVEARCH
  This is used to fill in the ExclusiveArch: field in the RPM .spec file.

X_RPM_GROUP
  This is used to fill in the Group: field in the RPM .spec file.

X_RPM_GROUP_lang
  This is used to fill in the Group(lang): field in the RPM .spec file. Note that lang is not literal and should be replaced by the appropriate language code.

X_RPM_ICON
  This is used to fill in the Icon: field in the RPM .spec file.

X_RPM_INSTALL
  internal, but overridable

X_RPM_PACKAGER
  This is used to fill in the Packager: field in the RPM .spec file.

X_RPM_POSTINSTALL
  This is used to fill in the %post: section in the RPM .spec file.

X_RPM_POSTUNINSTALL
  This is used to fill in the %postun: section in the RPM .spec file.

X_RPM_PREFIX
  This is used to fill in the Prefix: field in the RPM .spec file.

X_RPM_PREINSTALL
  This is used to fill in the %pre: section in the RPM .spec file.

X_RPM_PREP
  internal, but overridable

X_RPM_PREUNINSTALL
  This is used to fill in the %preun: section in the RPM .spec file.

X_RPM_PROVIDES
  This is used to fill in the Provides: field in the RPM .spec file.

X_RPM_REQUIRES
  This is used to fill in the Requires: field in the RPM .spec file.

X_RPM_SERIAL
  This is used to fill in the Serial: field in the RPM .spec file.

X_RPM_URL
  This is used to fill in the Url: field in the RPM .spec file.

YACC
  The parser generator.

YACCCOM
  The command line used to call the parser generator to generate a source file.

YACCCOMSTR
  The string displayed when generating a source file using the parser generator. If this is not set, then $YACCCOM (the command line) is displayed.

        env = Environment(YACCCOMSTR = "Yacc'ing $TARGET from $SOURCES")

YACCFLAGS
  General options passed to the parser generator. If $YACCFLAGS contains a -d option, SCons assumes that the call will also create a .h file (if the yacc source file ends in a .y suffix) or a .hpp file (if the yacc source file ends in a .yy suffix)

YACCHFILESUFFIX
  The suffix of the C header file generated by the parser generator when the -d option is used. Note that setting this variable does not cause the parser generator to generate a header file with the specified suffix, it exists to allow you to specify what suffix the parser generator will use of its own accord. The default value is .h.

YACCHXXFILESUFFIX
  The suffix of the C++ header file generated by the parser generator when the -d option is used. Note that setting this variable does not cause the parser generator to generate a header file with the specified suffix, it exists to allow you to specify what suffix the parser generator will use of its own accord. The default value is .hpp, except on Mac OS X, where the default is ${TARGET.suffix}.h. because the default &bison; parser generator just appends .h to the name of the generated C++ file.

YACCVCGFILESUFFIX
  The suffix of the file containing the VCG grammar automaton definition when the --graph= option is used. Note that setting this variable does not cause the parser generator to generate a VCG file with the specified suffix, it exists to allow you to specify what suffix the parser generator will use of its own accord. The default value is .vcg.

ZIP
  The zip compression and file packaging utility.

ZIPCOM
  The command line used to call the zip utility, or the internal Python function used to create a zip archive.

ZIPCOMPRESSION
  The compression flag from the Python zipfile module used by the internal Python function to control whether the zip archive is compressed or not. The default value is zipfile.ZIP_DEFLATED, which creates a compressed zip archive. This value has no effect when using Python 1.5.2 or if the zipfile module is otherwise unavailable.

ZIPCOMSTR
  The string displayed when archiving files using the zip utility. If this is not set, then $ZIPCOM (the command line or internal Python function) is displayed.

        env = Environment(ZIPCOMSTR = "Zipping $TARGET")

ZIPFLAGS
  General options passed to the zip utility.

ZIPSUFFIX
  The suffix used for zip file names.

Construction variables can be retrieved and set using the Dictionary method of the construction environment:

      dict = env.Dictionary()
      dict["CC"] = "cc"

or using the [] operator:

      env["CC"] = "cc"

Construction variables can also be passed to the construction environment constructor:

      env = Environment(CC="cc")

or when copying a construction environment using the Clone method:

      env2 = env.Clone(CC="cl.exe")

### Configure Contexts

scons supports configure contexts, an integrated mechanism similar to the various AC_CHECK macros in GNU autoconf for testing for the existence of C header files, libraries, etc. In contrast to autoconf, scons does not maintain an explicit cache of the tested values, but uses its normal dependency tracking to keep the checked values up to date. However, users may override this behaviour with the --config command line option.

The following methods can be used to perform checks:

Configure(env, [custom_tests, conf_dir, log_file, config_h, clean, help])
env.Configure([custom_tests, conf_dir, log_file, config_h, clean, help])
  This creates a configure context, which can be used to perform checks. env specifies the environment for building the tests. This environment may be modified when performing checks. custom_tests is a dictionary containing custom tests. See also the section about custom tests below. By default, no custom tests are added to the configure context. conf_dir specifies a directory where the test cases are built. Note that this directory is not used for building normal targets. The default value is the directory #/.sconf_temp. log_file specifies a file which collects the output from commands that are executed to check for the existence of header files, libraries, etc. The default is the file #/config.log. If you are using the VariantDir method, you may want to specify a subdirectory under your variant directory. config_h specifies a C header file where the results of tests will be written, e.g. #define HAVE_STDIO_H, #define HAVE_LIBM, etc. The default is to not write a config.h file. You can specify the same config.h file in multiple calls to Configure, in which case scons will concatenate all results in the specified file. Note that SCons uses its normal dependency checking to decide if it's necessary to rebuild the specified config_h file. This means that the file is not necessarily re-built each time scons is run, but is only rebuilt if its contents will have changed and some target that depends on the config_h file is being built.

  The optional clean and help arguments can be used to suppress execution of the configuration tests when the -c/--clean or -H/-h/--help options are used, respectively. The default behavior is always to execute configure context tests, since the results of the tests may affect the list of targets to be cleaned or the help text. If the configure tests do not affect these, then you may add the clean=False or help=False arguments (or both) to avoid unnecessary test execution.

  A created Configure instance has the following associated methods:

Configure.Finish(self)
  This method should be called after configuration is done. It returns the environment as modified by the configuration checks performed. After this method is called, no further checks can be performed with this configuration context. However, you can create a new Configure context to perform additional checks. Only one context should be active at a time.

  The following Checks are predefined. (This list will likely grow larger as time goes by and developers contribute new useful tests.)

Configure.CheckHeader(self, header, [include_quotes, language])
  Checks if header is usable in the specified language. header may be a list, in which case the last item in the list is the header file to be checked, and the previous list items are header files whose #include lines should precede the header line being checked for. The optional argument include_quotes must be a two character string, where the first character denotes the opening quote and the second character denotes the closing quote. By default, both characters are " (double quote). The optional argument language should be either C or C++ and selects the compiler to be used for the check. Returns 1 on success and 0 on failure.

Configure.CheckCHeader(self, header, [include_quotes])
  This is a wrapper around Configure.CheckHeader which checks if header is usable in the C language. header may be a list, in which case the last item in the list is the header file to be checked, and the previous list items are header files whose #include lines should precede the header line being checked for. The optional argument include_quotes must be a two character string, where the first character denotes the opening quote and the second character denotes the closing quote (both default to "). Returns 1 on success and 0 on failure.

Configure.CheckCXXHeader(self, header, [include_quotes])
  This is a wrapper around Configure.CheckHeader which checks if header is usable in the C++ language. header may be a list, in which case the last item in the list is the header file to be checked, and the previous list items are header files whose #include lines should precede the header line being checked for. The optional argument include_quotes must be a two character string, where the first character denotes the opening quote and the second character denotes the closing quote (both default to "). Returns 1 on success and 0 on failure.

Configure.CheckFunc(self, function_name, [header, language])
  Checks if the specified C or C++ function is available. function_name is the name of the function to check for. The optional header argument is a string that will be placed at the top of the test file that will be compiled to check if the function exists; the default is:

        #ifdef __cplusplus
        extern "C"
        #endif
        char function_name();

  The optional language argument should be C or C++ and selects the compiler to be used for the check; the default is "C".

Configure.CheckLib(self, [library, symbol, header, language, autoadd=1])
  Checks if library provides symbol. If the value of autoadd is 1 and the library provides the specified symbol, appends the library to the LIBS construction environment variable. library may also be None (the default), in which case symbol is checked with the current LIBS variable, or a list of library names, in which case each library in the list will be checked for symbol. If symbol is not set or is None, then Configure.CheckLib() just checks if you can link against the specified library. The optional language argument should be C or C++ and selects the compiler to be used for the check; the default is "C". The default value for autoadd is 1. This method returns 1 on success and 0 on error.

Configure.CheckLibWithHeader(self, library, header, language, [call, autoadd])

  In contrast to the Configure.CheckLib call, this call provides a more sophisticated way to check against libraries. Again, library specifies the library or a list of libraries to check. header specifies a header to check for. header may be a list, in which case the last item in the list is the header file to be checked, and the previous list items are header files whose #include lines should precede the header line being checked for. language may be one of 'C','c','CXX','cxx','C++' and 'c++'. call can be any valid expression (with a trailing ';'). If call is not set, the default simply checks that you can link against the specified library. autoadd specifies whether to add the library to the environment (only if the check succeeds). This method returns 1 on success and 0 on error.

Configure.CheckType(self, type_name, [includes, language])
  Checks for the existence of a type defined by typedef. type_name specifies the typedef name to check for. includes is a string containing one or more #include lines that will be inserted into the program that will be run to test for the existence of the type. The optional language argument should be C or C++ and selects the compiler to be used for the check; the default is "C".

  Example of a typical Configure usage:

        env = Environment()
        conf = Configure( env )
        if not conf.CheckCHeader( 'math.h' ):
            print 'We really need math.h!'
            Exit(1)
        if conf.CheckLibWithHeader( 'qt', 'qapp.h', 'c++', 'QApplication qapp(0,0);' ):
            # do stuff for qt - usage, e.g.
            conf.env.Append( CPPFLAGS = '-DWITH_QT' )
        env = conf.Finish()

Configure.CheckTypeSize(self, type_name, [header, language, expect])
  Checks for the size of a type defined by typedef. type_name specifies the typedef name to check for. The optional header argument is a string that will be placed at the top of the test file that will be compiled to check if the function exists; the default is empty. The optional language argument should be C or C++ and selects the compiler to be used for the check; the default is "C". The optional expect argument should be an integer. If this argument is used, the function will only check whether the type given in type_name has the expected size (in bytes). For example, CheckTypeSize('short', expect = 2) will return success only if short is two bytes.

Configure.CheckDeclaration(self, symbol, [includes, language])
  Checks if the specified symbol is declared. includes is a string containing one or more #include lines that will be inserted into the program that will be run to test for the existence of the type. The optional language argument should be C or C++ and selects the compiler to be used for the check; the default is "C".

Configure.Define(self, symbol, [value, comment])
  This function does not check for anything, but defines a preprocessor symbol that will be added to the configuration header file. It is the equivalent of AC_DEFINE, and defines the symbol name with the optional value and the optional comment comment.

  Examples:

        env = Environment()
        conf = Configure( env )

        # Puts the following line in the config header file:
        #    #define A_SYMBOL
        conf.Define('A_SYMBOL')

        # Puts the following line in the config header file:
        #    #define A_SYMBOL 1
        conf.Define('A_SYMBOL', 1)

  Be careful about quoting string values, though:

        env = Environment()
        conf = Configure( env )

        # Puts the following line in the config header file:
        #    #define A_SYMBOL YA
        conf.Define('A_SYMBOL', "YA")

        # Puts the following line in the config header file:
        #    #define A_SYMBOL "YA"
        conf.Define('A_SYMBOL', '"YA"')

  For comment:

        env = Environment()
        conf = Configure( env )

        # Puts the following lines in the config header file:
        #    /* Set to 1 if you have a symbol */
        #    #define A_SYMBOL 1
        conf.Define('A_SYMBOL', 1, 'Set to 1 if you have a symbol')

  You can define your own custom checks. in addition to the predefined checks. These are passed in a dictionary to the Configure function. This dictionary maps the names of the checks to user defined Python callables (either Python functions or class instances implementing the __call__ method). The first argument of the call is always a CheckContext instance followed by the arguments, which must be supplied by the user of the check. These CheckContext instances define the following methods:

CheckContext.Message(self, text)

  Usually called before the check is started. text will be displayed to the user, e.g. 'Checking for library X...'

CheckContext.Result(self,, res)

  Usually called after the check is done. res can be either an integer or a string. In the former case, 'ok' (res != 0) or 'failed' (res == 0) is displayed to the user, in the latter case the given string is displayed.

CheckContext.TryCompile(self, text, extension)
  Checks if a file with the specified extension (e.g. '.c') containing text can be compiled using the environment's Object builder. Returns 1 on success and 0 on failure.

CheckContext.TryLink(self, text, extension)
  Checks, if a file with the specified extension (e.g. '.c') containing text can be compiled using the environment's Program builder. Returns 1 on success and 0 on failure.

CheckContext.TryRun(self, text, extension)
  Checks, if a file with the specified extension (e.g. '.c') containing text can be compiled using the environment's Program builder. On success, the program is run. If the program executes successfully (that is, its return status is 0), a tuple (1, outputStr) is returned, where outputStr is the standard output of the program. If the program fails execution (its return status is non-zero), then (0, '') is returned.

CheckContext.TryAction(self, action, [text, extension])
  Checks if the specified action with an optional source file (contents text , extension extension = '' ) can be executed. action may be anything which can be converted to a scons Action. On success, (1, outputStr) is returned, where outputStr is the content of the target file. On failure (0, '') is returned.

CheckContext.TryBuild(self, builder, [text, extension])
  Low level implementation for testing specific builds; the methods above are based on this method. Given the Builder instance builder and the optional text of a source file with optional extension, this method returns 1 on success and 0 on failure. In addition, self.lastTarget is set to the build target node, if the build was successful.

  Example for implementing and using custom tests:

        def CheckQt(context, qtdir):
            context.Message( 'Checking for qt ...' )
            lastLIBS = context.env['LIBS']
            lastLIBPATH = context.env['LIBPATH']
            lastCPPPATH= context.env['CPPPATH']
            context.env.Append(LIBS = 'qt', LIBPATH = qtdir + '/lib', CPPPATH = qtdir + '/include' )
            ret = context.TryLink("""
        #include <qapp.h>
        int main(int argc, char **argv) {
          QApplication qapp(argc, argv);
          return 0;
        }
        """)
            if not ret:
                context.env.Replace(LIBS = lastLIBS, LIBPATH=lastLIBPATH, CPPPATH=lastCPPPATH)
            context.Result( ret )
            return ret

        env = Environment()
        conf = Configure( env, custom_tests = { 'CheckQt' : CheckQt } )
        if not conf.CheckQt('/usr/lib/qt'):
            print 'We really need qt!'
            Exit(1)
        env = conf.Finish()

### Construction Variable Options

Often when building software, various options need to be specified at build time that are not known when the SConstruct/SConscript files are written. For example, libraries needed for the build may be in non-standard locations, or site-specific compiler options may need to be passed to the compiler. scons provides an Options object for overridding construction variables on the command line:

      $ scons VARIABLE=foo

The variable values can also be specified in a text-based SConscript file. To create an Options object, call the Options() function:

Options([files], [args])
  This creates an Options object that will read construction variables from the file or list of filenames specified in files. If no files are specified, or the files argument is None, then no files will be read. The optional argument args is a dictionary of values that will override anything read from the specified files; it is primarily intended to be passed the ARGUMENTS dictionary that holds variables specified on the command line. Example:

        opts = Options('custom.py')
        opts = Options('overrides.py', ARGUMENTS)
        opts = Options(None, {FOO:'expansion', BAR:7})

  Options objects have the following methods:

Add(key, [help, default, validator, converter])
  This adds a customizable construction variable to the Options object. key is the name of the variable. help is the help text for the variable. default is the default value of the variable; if the default value is None and there is no explicit value specified, the construction variable will not be added to the construction environment. validator is called to validate the value of the variable, and should take three arguments: key, value, and environment. The recommended way to handle an invalid value is to raise an exception (see example below). converter is called to convert the value before putting it in the environment, and should take either a value, or the value and environment, as parameters. The converter must return a value, which will be converted into a string before being validated by the validator (if any) and then added to the environment.

  Examples:

        opts.Add('CC', 'The C compiler')

        def validate_color(key, val, env):
            if not val in ['red', 'blue', 'yellow']:
                raise "Invalid color value '%s'" % val
        opts.Add('COLOR', validator=valid_color)

AddOptions(list)
  A wrapper script that adds multiple customizable construction variables to an Options object. list is a list of tuple or list objects that contain the arguments for an individual call to the Add method.

        opt.AddOptions(
               ('debug', '', 0),
               ('CC', 'The C compiler'),
               ('VALIDATE', 'An option for testing validation',
                'notset', validator, None),
            )

Update(env, [args])
  This updates a construction environment env with the customized construction variables. Any specified variables that are not configured for the Options object will be saved and may be retrieved with the UnknownOptions() method, below.

  Normally this method is not called directly, but is called indirectly by passing the Options object to the Environment() function:

        env = Environment(options=opts)

  The text file(s) that were specified when the Options object was created are executed as Python scripts, and the values of (global) Python variables set in the file are added to the construction environment.

  Example:

        CC = 'my_cc'

UnknownOptions()
  Returns a dictionary containing any variables that were specified either in the files or the dictionary with which the Options object was intialized, but for which the Options object was not configured.

        env = Environment(options=opts)
        for key, value in opts.UnknownOptions():
            print "unknown variable:  %s=%s" % (key, value)

Save(filename, env)
  This saves the currently set options into a script file named filename that can be used on the next invocation to automatically load the current settings. This method combined with the Options method can be used to support caching of options between runs.

        env = Environment()
        opts = Options(['options.cache', 'custom.py'])
        opts.Add(...)
        opts.Update(env)
        opts.Save('options.cache', env)

GenerateHelpText(env, [sort])
  This generates help text documenting the customizable construction variables suitable to passing in to the Help() function. env is the construction environment that will be used to get the actual values of customizable variables. Calling with an optional sort function will cause the output to be sorted by the specified argument. The specific sort function should take two arguments and return -1, 0 or 1 (like the standard Python cmp function).

        Help(opts.GenerateHelpText(env))
        Help(opts.GenerateHelpText(env, sort=cmp))

FormatOptionHelpText(env, opt, help, default, actual)
  This method returns a formatted string containing the printable help text for one option. It is normally not called directly, but is called by the GenerateHelpText() method to create the returned help text. It may be overridden with your own function that takes the arguments specified above and returns a string of help text formatted to your liking. Note that the GenerateHelpText() will not put any blank lines or extra characters in between the entries, so you must add those characters to the returned string if you want the entries separated.

        def my_format(env, opt, help, default, actual):
            fmt = "s: default=%s actual=%s (%s)
            return fmt % (opt, default. actual, help)
        opts.FormatOptionHelpText = my_format

  To make it more convenient to work with customizable Options, scons provides a number of functions that make it easy to set up various types of Options:

BoolOption(key, help, default)
  Return a tuple of arguments to set up a Boolean option. The option will use the specified name key, have a default value of default, and display the specified help text. The option will interpret the values y, yes, t, true, 1, on and all as true, and the values n, no, f, false, 0, off and none as false.

EnumOption(key, help, default, allowed_values, [map, ignorecase])
  Return a tuple of arguments to set up an option whose value may be one of a specified list of legal enumerated values. The option will use the specified name key, have a default value of default, and display the specified help text. The option will only support those values in the allowed_values list. The optional map argument is a dictionary that can be used to convert input values into specific legal values in the allowed_values list. If the value of ignore_case is 0 (the default), then the values are case-sensitive. If the value of ignore_case is 1, then values will be matched case-insensitive. If the value of ignore_case is 1, then values will be matched case-insensitive, and all input values will be converted to lower case.

ListOption(key, help, default, names, [,map])
  Return a tuple of arguments to set up an option whose value may be one or more of a specified list of legal enumerated values. The option will use the specified name key, have a default value of default, and display the specified help text. The option will only support the values all, none, or the values in the names list. More than one value may be specified, with all values separated by commas. The default may be a string of comma-separated default values, or a list of the default values. The optional map argument is a dictionary that can be used to convert input values into specific legal values in the names list.

PackageOption(key, help, default)
  Return a tuple of arguments to set up an option whose value is a path name of a package that may be enabled, disabled or given an explicit path name. The option will use the specified name key, have a default value of default, and display the specified help text. The option will support the values yes, true, on, enable or search, in which case the specified default will be used, or the option may be set to an arbitrary string (typically the path name to a package that is being enabled). The option will also support the values no, false, off or disable to disable use of the specified option.

PathOption(key, help, default, [validator])
  Return a tuple of arguments to set up an option whose value is expected to be a path name. The option will use the specified name key, have a default value of default, and display the specified help text. An additional validator may be specified that will be called to verify that the specified path is acceptable. SCons supplies the following ready-made validators: PathOption.PathExists (the default), which verifies that the specified path exists; PathOption.PathIsFile, which verifies that the specified path is an existing file; PathOption.PathIsDir, which verifies that the specified path is an existing directory; PathOption.PathIsDirCreate, which verifies that the specified path is a directory and will create the specified directory if the path does not exist; and PathOption.PathAccept, which simply accepts the specific path name argument without validation, and which is suitable if you want your users to be able to specify a directory path that will be created as part of the build process, for example. You may supply your own validator function, which must take three arguments (key, the name of the options variable to be set; val, the specified value being checked; and env, the construction environment) and should raise an exception if the specified value is not acceptable.

  These functions make it convenient to create a number of options with consistent behavior in a single call to the AddOptions method:

        opts.AddOptions(
            BoolOption('warnings', 'compilation with -Wall and similiar', 1),
            EnumOption('debug', 'debug output and symbols', 'no'
                       allowed_values=('yes', 'no', 'full'),
                       map={}, ignorecase=0),  # case sensitive
            ListOption('shared',
                       'libraries to build as shared libraries',
                       'all',
                       names = list_of_libs),
            PackageOption('x11',
                          'use X11 installed here (yes = search some places)',
                          'yes'),
            PathOption('qtdir', 'where the root of Qt is installed', qtdir),
            PathOption('foopath', 'where the foo library is installed', foopath,
                       PathOption.PathIsDir),

        )

### File and Directory Nodes

The File() and Dir() functions return File and Dir Nodes, respectively. python objects, respectively. Those objects have several user-visible attributes and methods that are often useful:

path
  The build path of the given file or directory. This path is relative to the top-level directory (where the SConstruct file is found). The build path is the same as the source path if variant_dir is not being used.

abspath
  The absolute build path of the given file or directory.

srcnode()
  The srcnode() method returns another File or Dir object representing the source path of the given File or Dir. The

        # Get the current build dir's path, relative to top.
        Dir('.').path
        # Current dir's absolute path
        Dir('.').abspath
        # Next line is always '.', because it is the top dir's path relative to itself.
        Dir('#.').path
        File('foo.c').srcnode().path   # source path of the given source file.

        # Builders also return File objects:
        foo = env.Program('foo.c')
        print "foo will be built in %s"%foo.path

  A Dir Node or File Node can also be used to create file and subdirectory Nodes relative to the generating Node. A Dir Node will place the new Nodes within the directory it represents. A File node will place the new Nodes within its parent directory (that is, "beside" the file in question). If d is a Dir (directory) Node and f is a File (file) Node, then these methods are available:

d.Dir(name)
  Returns a directory Node for a subdirectory of d named name.

d.File(name)
  Returns a file Node for a file within d named name.

d.Entry(name)
  Returns an unresolved Node within d named name.

f.Dir(name)
  Returns a directory named name within the parent directory of f.

f.File(name)
  Returns a file named name within the parent directory of f.

f.Entry(name)
  Returns an unresolved Node named name within the parent directory of f.

  For example:

        # Get a Node for a file within a directory
        incl = Dir('include')
        f = incl.File('header.h')

        # Get a Node for a subdirectory within a directory
        dist = Dir('project-3.2.1)
        src = dist.Dir('src')

        # Get a Node for a file in the same directory
        cfile = File('sample.c')
        hfile = cfile.File('sample.h')

        # Combined example
        docs = Dir('docs')
        html = docs.Dir('html')
        index = html.File('index.html')
        css = index.File('app.css')

## EXTENDING SCONS

### Builder Objects

scons can be extended to build different types of targets by adding new Builder objects to a construction environment. In general, you should only need to add a new Builder object when you want to build a new type of file or other external target. If you just want to invoke a different compiler or other tool to build a Program, Object, Library, or any other type of output file for which scons already has an existing Builder, it is generally much easier to use those existing Builders in a construction environment that sets the appropriate construction variables (CC, LINK, etc.).

Builder objects are created using the Builder function. The Builder function accepts the following arguments:

action
  The command line string used to build the target from the source. action can also be: a list of strings representing the command to be executed and its arguments (suitable for enclosing white space in an argument), a dictionary mapping source file name suffixes to any combination of command line strings (if the builder should accept multiple source file extensions), a Python function; an Action object (see the next section); or a list of any of the above.

  An action function takes three arguments: source - a list of source nodes, target - a list of target nodes, env - the construction environment.

prefix
  The prefix that will be prepended to the target file name. This may be specified as a:

    * string,

    * callable object - a function or other callable that takes
      two arguments (a construction environment and a list of sources) and returns a prefix,

    * dictionary - specifies a mapping from a specific source suffix (of the first
      source specified) to a corresponding target prefix. Both the source suffix and target prefix specifications may use environment variable substitution, and the target prefix (the 'value' entries in the dictionary) may also be a callable object. The default target prefix may be indicated by a dictionary entry with a key value of None.

      b = Builder("build_it < $SOURCE > $TARGET"
                  prefix = "file-")

      def gen_prefix(env, sources):
          return "file-" + env['PLATFORM'] + '-'
      b = Builder("build_it < $SOURCE > $TARGET",
                  prefix = gen_prefix)

      b = Builder("build_it < $SOURCE > $TARGET",
                  suffix = { None: "file-",
                             "$SRC_SFX_A": gen_prefix })

suffix
  The suffix that will be appended to the target file name. This may be specified in the same manner as the prefix above. If the suffix is a string, then scons will append a '.' to the beginning of the suffix if it's not already there. The string returned by callable object (or obtained from the dictionary) is untouched and must append its own '.' to the beginning if one is desired.

        b = Builder("build_it < $SOURCE > $TARGET"
                    suffix = "-file")

        def gen_suffix(env, sources):
            return "." + env['PLATFORM'] + "-file"
        b = Builder("build_it < $SOURCE > $TARGET",
                    suffix = gen_suffix)

        b = Builder("build_it < $SOURCE > $TARGET",
                    suffix = { None: ".sfx1",
                               "$SRC_SFX_A": gen_suffix })

ensure_suffix
  When set to any true value, causes scons to add the target suffix specified by the suffix keyword to any target strings that have a different suffix. (The default behavior is to leave untouched any target file name that looks like it already has any suffix.)

        b1 = Builder("build_it < $SOURCE > $TARGET"
                     suffix = ".out")
        b2 = Builder("build_it < $SOURCE > $TARGET"
                     suffix = ".out",
                     ensure_suffix)
        env = Environment()
        env['BUILDERS']['B1'] = b1
        env['BUILDERS']['B2'] = b2

        # Builds "foo.txt" because ensure_suffix is not set.
        env.B1('foo.txt', 'foo.in')

        # Builds "bar.txt.out" because ensure_suffix is set.
        env.B2('bar.txt', 'bar.in')

src_suffix
  The expected source file name suffix. This may be a string or a list of strings.

target_scanner
  A Scanner object that will be invoked to find implicit dependencies for this target file. This keyword argument should be used for Scanner objects that find implicit dependencies based only on the target file and the construction environment, not for implicit (See the section "Scanner Objects," below, for information about creating Scanner objects.)

source_scanner
  A Scanner object that will be invoked to find implicit dependences in any source files used to build this target file. This is where you would specify a scanner to find things like #include lines in source files. The pre-built DirScanner Scanner object may be used to indicate that this Builder should scan directory trees for on-disk changes to files that scons does not know about from other Builder or function calls. (See the section "Scanner Objects," below, for information about creating your own Scanner objects.)

target_factory
  A factory function that the Builder will use to turn any targets specified as strings into SCons Nodes. By default, SCons assumes that all targets are files. Other useful target_factory values include Dir, for when a Builder creates a directory target, and Entry, for when a Builder can create either a file or directory target.

  Example:

        MakeDirectoryBuilder = Builder(action=my_mkdir, target_factory=Dir)
        env = Environment()
        env.Append(BUILDERS = {'MakeDirectory':MakeDirectoryBuilder})
        env.MakeDirectory('new_directory', [])

  Note that the call to the MakeDirectory Builder needs to specify an empty source list to make the string represent the builder's target; without that, it would assume the argument is the source, and would try to deduce the target name from it, which in the absence of an automatically-added prefix or suffix would lead to a matching target and source name and a circular dependency.

source_factory
  A factory function that the Builder will use to turn any sources specified as strings into SCons Nodes. By default, SCons assumes that all source are files. Other useful source_factory values include Dir, for when a Builder uses a directory as a source, and Entry, for when a Builder can use files or directories (or both) as sources.

  Example:

        CollectBuilder = Builder(action=my_mkdir, source_factory=Entry)
        env = Environment()
        env.Append(BUILDERS = {'Collect':CollectBuilder})
        env.Collect('archive', ['directory_name', 'file_name'])

emitter
  A function or list of functions to manipulate the target and source lists before dependencies are established and the target(s) are actually built. emitter can also be a string containing a construction variable to expand to an emitter function or list of functions, or a dictionary mapping source file suffixes to emitter functions. (Only the suffix of the first source file is used to select the actual emitter function from an emitter dictionary.)

  An emitter function takes three arguments: source - a list of source nodes, target - a list of target nodes, env - the construction environment. An emitter must return a tuple containing two lists, the list of targets to be built by this builder, and the list of sources for this builder.

  Example:

        def e(target, source, env):
            return (target + ['foo.foo'], source + ['foo.src'])

        # Simple association of an emitter function with a Builder.
        b = Builder("my_build < $TARGET > $SOURCE",
                    emitter = e)

        def e2(target, source, env):
            return (target + ['bar.foo'], source + ['bar.src'])

        # Simple association of a list of emitter functions with a Builder.
        b = Builder("my_build < $TARGET > $SOURCE",
                    emitter = [e, e2])

        # Calling an emitter function through a construction variable.
        env = Environment(MY_EMITTER = e)
        b = Builder("my_build < $TARGET > $SOURCE",
                    emitter = '$MY_EMITTER')

        # Calling a list of emitter functions through a construction variable.
        env = Environment(EMITTER_LIST = [e, e2])
        b = Builder("my_build < $TARGET > $SOURCE",
                    emitter = '$EMITTER_LIST')

        # Associating multiple emitters with different file
        # suffixes using a dictionary.
        def e_suf1(target, source, env):
            return (target + ['another_target_file'], source)
        def e_suf2(target, source, env):
            return (target, source + ['another_source_file'])
        b = Builder("my_build < $TARGET > $SOURCE",
                    emitter = {'.suf1' : e_suf1,
                               '.suf2' : e_suf2})

multi
  Specifies whether this builder is allowed to be called multiple times for the same target file(s). The default is 0, which means the builder can not be called multiple times for the same target file(s). Calling a builder multiple times for the same target simply adds additional source files to the target; it is not allowed to change the environment associated with the target, specify addition environment overrides, or associate a different builder with the target.

env
  A construction environment that can be used to fetch source code using this Builder. (Note that this environment is not used for normal builds of normal target files, which use the environment that was used to call the Builder for the target file.)

generator
  A function that returns a list of actions that will be executed to build the target(s) from the source(s). The returned action(s) may be an Action object, or anything that can be converted into an Action object (see the next section).

  The generator function takes four arguments: source - a list of source nodes, target - a list of target nodes, env - the construction environment, for_signature - a Boolean value that specifies whether the generator is being called for generating a build signature (as opposed to actually executing the command). Example:

        def g(source, target, env, for_signature):
            return [["gcc", "-c", "-o"] + target + source]

        b = Builder(generator=g)

  The generator and action arguments must not both be used for the same Builder.

src_builder
  Specifies a builder to use when a source file name suffix does not match any of the suffixes of the builder. Using this argument produces a multi-stage builder.

single_source
  Specifies that this builder expects exactly one source file per call. Giving more than one source files without target files results in implicitely calling the builder multiple times (once for each source given). Giving multiple source files together with target files results in a UserError exception.

  The generator and action arguments must not both be used for the same Builder.

source_ext_match
  When the specified action argument is a dictionary, the default behavior when a builder is passed multiple source files is to make sure that the extensions of all the source files match. If it is legal for this builder to be called with a list of source files with different extensions, this check can be suppressed by setting source_ext_match to None or some other non-true value. When source_ext_match is disable, scons will use the suffix of the first specified source file to select the appropriate action from the action dictionary.

  In the following example, the setting of source_ext_match prevents scons from exiting with an error due to the mismatched suffixes of foo.in and foo.extra.

        b = Builder(action={'.in' : 'build $SOURCES > $TARGET'},
                    source_ext_match = None)

        env = Environment(BUILDERS = {'MyBuild':b})
        env.MyBuild('foo.out', ['foo.in', 'foo.extra'])

env
  A construction environment that can be used to fetch source code using this Builder. (Note that this environment is not used for normal builds of normal target files, which use the environment that was used to call the Builder for the target file.)

        b = Builder(action="build < $SOURCE > $TARGET")
        env = Environment(BUILDERS = {'MyBuild' : b})
        env.MyBuild('foo.out', 'foo.in', my_arg = 'xyzzy')

chdir
  A directory from which scons will execute the action(s) specified for this Builder. If the chdir argument is a string or a directory Node, scons will change to the specified directory. If the chdir is not a string or Node and is non-zero, then scons will change to the target file's directory.

  Note that scons will not automatically modify its expansion of construction variables like $TARGET and $SOURCE when using the chdir keyword argument--that is, the expanded file names will still be relative to the top-level SConstruct directory, and consequently incorrect relative to the chdir directory. Builders created using chdir keyword argument, will need to use construction variable expansions like ${TARGET.file} and ${SOURCE.file} to use just the filename portion of the targets and source.

        b = Builder(action="build < ${SOURCE.file} > ${TARGET.file}",
                    chdir=1)
        env = Environment(BUILDERS = {'MyBuild' : b})
        env.MyBuild('sub/dir/foo.out', 'sub/dir/foo.in')

  WARNING: Python only keeps one current directory location for all of the threads. This means that use of the chdir argument will not work with the SCons -j option, because individual worker threads spawned by SCons interfere with each other when they start changing directory.

  Any additional keyword arguments supplied when a Builder object is created (that is, when the Builder() function is called) will be set in the executing construction environment when the Builder object is called. The canonical example here would be to set a construction variable to the repository of a source code system.

  Any additional keyword arguments supplied when a Builder object is called will only be associated with the target created by that particular Builder call (and any other files built as a result of the call).

  These extra keyword arguments are passed to the following functions: command generator functions, function Actions, and emitter functions.

### Action Objects

The Builder() function will turn its action keyword argument into an appropriate internal Action object. You can also explicity create Action objects using the Action() global function, which can then be passed to the Builder() function. This can be used to configure an Action object more flexibly, or it may simply be more efficient than letting each separate Builder object create a separate Action when multiple Builder objects need to do the same thing.

The Action() global function returns an appropriate object for the action represented by the type of the first argument:

Action
  If the first argument is already an Action object, the object is simply returned.

String
  If the first argument is a string, a command-line Action is returned. Note that the command line string may be preceded by an @ (at-sign) to suppress printing of the specified command line, or by a - (hyphen) to ignore the exit status from the specified command. Examples:

        Action('$CC -c -o $TARGET $SOURCES')

        # Doesn't print the line being executed.
        Action('@build $TARGET $SOURCES')

        # Ignores
        Action('-build $TARGET $SOURCES')

List
  If the first argument is a list, then a list of Action objects is returned. An Action object is created as necessary for each element in the list. If an element within the list is itself a list, the internal list is the command and arguments to be executed via the command line. This allows white space to be enclosed in an argument by defining a command in a list within a list:

        Action([['cc', '-c', '-DWHITE SPACE', '-o', '$TARGET', '$SOURCES']])

Function
  If the first argument is a Python function, a function Action is returned. The Python function takes three keyword arguments, target (a Node object representing the target file), source (a Node object representing the source file) and env (the construction environment used for building the target file). The target and source arguments may be lists of Node objects if there is more than one target file or source file. The actual target and source file name(s) may be retrieved from their Node objects via the built-in Python str() function:

        target_file_name = str(target)
        source_file_names = map(lambda x: str(x), source)

  The function should return 0 or None to indicate a successful build of the target file(s). The function may raise an exception or return a non-zero exit status to indicate an unsuccessful build.

        def build_it(target = None, source = None, env = None):
            # build the target from the source
            return 0

        a = Action(build_it)

  If the action argument is not one of the above, None is returned.

The second, optional argument is used to define the output which is printed when the Action is actually performed. In the absence of this parameter, or if it's an empty string, a default output depending on the type of the action is used. For example, a command-line action will print the executed command. The argument is either a python function or a string.

In the first case, it's a function that returns a string to be printed to describe the action being executed. Like a function to build a file, this function takes three arguments: target (a Node object representing the target file), source (a Node object representing the source file) and env (a construction environment). The target and source arguments may be lists of Node objects if there is more than one target file or source file.

In the second case, you provide the string itself. The string typically contains variables, notably $TARGET(S) and $SOURCE(S), or consists of just a single variable, which is optionally defined somewhere else. SCons itself heavily uses the latter variant.

Examples:

      def build_it(target, source, env):
          # build the target from the source
          return 0

      def string_it(target, source, env):
          return "building '%s' from '%s'" % (target[0], source[0])

      # Use a positional argument.
      f = Action(build_it, string_it)
      s = Action(build_it, "building '$TARGET' from '$SOURCE'")

      # Alternatively, use a keyword argument.
      f = Action(build_it, strfunction=string_it)
      s = Action(build_it, cmdstr="building '$TARGET' from '$SOURCE'")

      # You can provide a configurable variable.
      l = Action(build_it, '$STRINGIT')

The third, also optional argument is a list of construction variables whose values will be included in the signature of the Action when deciding whether a target should be rebuilt because the action changed. This is necessary whenever you want a target to be rebuilt when a specific construction variable changes, because the underlying Python code for a function will not change when the value of the construction variable does.

      def build_it(target, source, env):
          # build the target from the 'XXX' construction variable
          open(target[0], 'w').write(env['XXX'])
          return 0

      # Use positional arguments.
      a = Action(build_it, '$STRINGIT', ['XXX'])

      # Alternatively, use a keyword argument.
      a = Action(build_it, varlist=['XXX'])

The Action() global function also takes a chdir keyword argument which specifies that scons will execute the action after changing to the specified directory. If the chdir argument is a string or a directory Node, scons will change to the specified directory. If the chdir argument is not a string or Node and is non-zero, then scons will change to the target file's directory.

Note that scons will not automatically modify its expansion of construction variables like $TARGET and $SOURCE when using the chdir keyword argument--that is, the expanded file names will still be relative to the top-level SConstruct directory, and consequently incorrect relative to the chdir directory. Builders created using chdir keyword argument, will need to use construction variable expansions like ${TARGET.file} and ${SOURCE.file} to use just the filename portion of the targets and source.

      a = Action("build < ${SOURCE.file} > ${TARGET.file}",
                 chdir=1)

The Action() global function also takes an exitstatfunc keyword argument which specifies a function that is passed the exit status (or return value) from the specified action and can return an arbitrary or modified value. This can be used, for example, to specify that an Action object's return value should be ignored and SCons should, therefore, consider that the action always suceeds:

      def always_succeed(s):
          # Always return 0, which indicates success.
          return 0
      a = Action("build < ${SOURCE.file} > ${TARGET.file}",
                 exitstatfunc=always_succeed)

### Miscellaneous Action Functions

scons supplies a number of functions that arrange for various common file and directory manipulations to be performed. These are similar in concept to "tasks" in the Ant build tool, although the implementation is slightly different. These functions do not actually perform the specified action at the time the function is called, but instead return an Action object that can be executed at the appropriate time. (In Object-Oriented terminology, these are actually Action Factory functions that return Action objects.)

In practice, there are two natural ways that these Action Functions are intended to be used.

First, if you need to perform the action at the time the SConscript file is being read, you can use the Execute global function to do so:

      Execute(Touch('file'))

Second, you can use these functions to supply Actions in a list for use by the Command method. This can allow you to perform more complicated sequences of file manipulation without relying on platform-specific external commands: that

      env = Environment(TMPBUILD = '/tmp/builddir')
      env.Command('foo.out', 'foo.in',
                  [Mkdir('$TMPBUILD'),
                   Copy('$TMPBUILD', '${SOURCE.dir}'),
                   "cd $TMPBUILD && make",
                   Delete('$TMPBUILD')])

Chmod(dest, mode)
  Returns an Action object that changes the permissions on the specified dest file or directory to the specified mode. Examples:

        Execute(Chmod('file', 0755))

        env.Command('foo.out', 'foo.in',
                    [Copy('$TARGET', '$SOURCE'),
                     Chmod('$TARGET', 0755)])

Copy(dest, src)
  Returns an Action object that will copy the src source file or directory to the dest destination file or directory. Examples:

        Execute(Copy('foo.output', 'foo.input'))

        env.Command('bar.out', 'bar.in',
                    Copy('$TARGET', '$SOURCE'))

Delete(entry, [must_exist])
  Returns an Action that deletes the specified entry, which may be a file or a directory tree. If a directory is specified, the entire directory tree will be removed. If the must_exist flag is set, then a Python error will be thrown if the specified entry does not exist; the default is must_exist=0, that is, the Action will silently do nothing if the entry does not exist. Examples:

        Execute(Delete('/tmp/buildroot'))

        env.Command('foo.out', 'foo.in',
                    [Delete('${TARGET.dir}'),
                     MyBuildAction])

        Execute(Delete('file_that_must_exist', must_exist=1))

Mkdir(dir)
  Returns an Action that creates the specified directory dir . Examples:

        Execute(Mkdir('/tmp/outputdir'))

        env.Command('foo.out', 'foo.in',
                    [Mkdir('/tmp/builddir',
                     Copy('$SOURCE', '/tmp/builddir')
                     "cd /tmp/builddir && ])

Move(dest, src)
  Returns an Action that moves the specified src file or directory to the specified dest file or directory. Examples:

        Execute(Move('file.destination', 'file.source'))

        env.Command('output_file', 'input_file',
                    [MyBuildAction,
                     Move('$TARGET', 'file_created_by_MyBuildAction')])

Touch(file)
  Returns an Action that updates the modification time on the specified file. Examples:

        Execute(Touch('file_to_be_touched'))

        env.Command('marker', 'input_file',
                    [MyBuildAction,
                     Touch('$TARGET')])

### Variable Substitution

Before executing a command, scons performs construction variable interpolation on the strings that make up the command line of builders. Variables are introduced by a $ prefix. Besides construction variables, scons provides the following variables for each command execution:

TARGET
  The file name of the target being built, or the file name of the first target if multiple targets are being built.

TARGETS
  The file names of all targets being built.

SOURCE
  The file name of the source of the build command, or the file name of the first source if multiple sources are being built.

SOURCES
  The file names of the sources of the build command.

  (Note that the above variables are reserved and may not be set in a construction environment.)

For example, given the construction variable CC='cc', targets=['foo'], and sources=['foo.c', 'bar.c']:

      action='$CC -c -o $TARGET $SOURCES'

would produce the command line:

      cc -c -o foo foo.c bar.c

Variable names may be surrounded by curly braces ({}) to separate the name from the trailing characters. Within the curly braces, a variable name may have a Python slice subscript appended to select one or more items from a list. In the previous example, the string:

      ${SOURCES[1]}

would produce:

      bar.c

Additionally, a variable name may have the following special modifiers appended within the enclosing curly braces to modify the interpolated string:

base
  The base path of the file name, including the directory path but excluding any suffix.

dir
  The name of the directory in which the file exists.

file
  The file name, minus any directory portion.

filebase
  Just the basename of the file, minus any suffix and minus the directory.

suffix
  Just the file suffix.

abspath
  The absolute path name of the file.

posix
  The POSIX form of the path, with directories separated by / (forward slashes) not backslashes. This is sometimes necessary on Windows systems when a path references a file on other (POSIX) systems.

srcpath
  The directory and file name to the source file linked to this file through VariantDir. If this file isn't linked, it just returns the directory and filename unchanged.

srcdir
  The directory containing the source file linked to this file through VariantDir. If this file isn't linked, it just returns the directory part of the filename.

rsrcpath
  The directory and file name to the source file linked to this file through VariantDir. If the file does not exist locally but exists in a Repository, the path in the Repository is returned. If this file isn't linked, it just returns the directory and filename unchanged.

rsrcdir
  The Repository directory containing the source file linked to this file through VariantDir. If this file isn't linked, it just returns the directory part of the filename.

For example, the specified target will expand as follows for the corresponding modifiers:

      $TARGET              => sub/dir/file.x
      ${TARGET.base}       => sub/dir/file
      ${TARGET.dir}        => sub/dir
      ${TARGET.file}       => file.x
      ${TARGET.filebase}   => file
      ${TARGET.suffix}     => .x
      ${TARGET.abspath}    => /top/dir/sub/dir/file.x

      SConscript('src/SConscript', variant_dir='sub/dir')
      $SOURCE              => sub/dir/file.x
      ${SOURCE.srcpath}    => src/file.x
      ${SOURCE.srcdir}     => src

      Repository('/usr/repository')
      $SOURCE              => sub/dir/file.x
      ${SOURCE.rsrcpath}   => /usr/repository/src/file.x
      ${SOURCE.rsrcdir}    => /usr/repository/src

Note that curly braces braces may also be used to enclose arbitrary Python code to be evaluated. (In fact, this is how the above modifiers are substituted, they are simply attributes of the Python objects that represent TARGET, SOURCES, etc.) See the section "Python Code Substitution," below, for more thorough examples of how this can be used.

Lastly, a variable name may be a callable Python function associated with a construction variable in the environment. The function should take four arguments: target - a list of target nodes, source - a list of source nodes, env - the construction environment, for_signature - a Boolean value that specifies whether the function is being called for generating a build signature. SCons will insert whatever the called function returns into the expanded string:

      def foo(target, source, env, for_signature):
          return "bar"

      # Will expand $BAR to "bar baz"
      env=Environment(FOO=foo, BAR="$FOO baz")

You can use this feature to pass arguments to a Python function by creating a callable class that stores one or more arguments in an object, and then uses them when the __call__() method is called. Note that in this case, the entire variable expansion must be enclosed by curly braces so that the arguments will be associated with the instantiation of the class:

      class foo:
          def __init__(self, arg):
              self.arg = arg

          def __call__(self, target, source, env, for_signature):
              return self.arg + " bar"

      # Will expand $BAR to "my argument bar baz"
      env=Environment(FOO=foo, BAR="${FOO('my argument')} baz")

The special pseudo-variables $( and $) may be used to surround parts of a command line that may change without causing a rebuild--that is, which are not included in the signature of target files built with this command. All text between $( and $) will be removed from the command line before it is added to file signatures, and the $( and $) will be removed before the command is executed. For example, the command line:

      echo Last build occurred $( $TODAY $). > $TARGET

would execute the command:

      echo Last build occurred $TODAY. > $TARGET

but the command signature added to any target files would be:

      echo Last build occurred  . > $TARGET

### Python Code Substitution

Any python code within ${-} pairs gets evaluated by python 'eval', with the python globals set to the current environment's set of construction variables. So in the following case:

      env['COND'] = 0
      env.Command('foo.out', 'foo.in',
         '''echo ${COND==1 and 'FOO' or 'BAR'} > $TARGET''')

the command executed will be either

      echo FOO > foo.out

or

      echo BAR > foo.out

according to the current value of env['COND'] when the command is executed. The evaluation occurs when the target is being built, not when the SConscript is being read. So if env['COND'] is changed later in the SConscript, the final value will be used.

Here's a more interesting example. Note that all of COND, FOO, and BAR are environment variables, and their values are substituted into the final command. FOO is a list, so its elements are interpolated separated by spaces.

      env=Environment()
      env['COND'] = 0
      env['FOO'] = ['foo1', 'foo2']
      env['BAR'] = 'barbar'
      env.Command('foo.out', 'foo.in',
          'echo ${COND==1 and FOO or BAR} > $TARGET')

      # Will execute this:
      #  echo foo1 foo2 > foo.out

SCons uses the following rules when converting construction variables into command lines:

String
  When the value is a string it is interpreted as a space delimited list of command line arguments.

List
  When the value is a list it is interpreted as a list of command line arguments. Each element of the list is converted to a string.

Other
  Anything that is not a list or string is converted to a string and interpreted as a single command line argument.

Newline
  Newline characters (\n) delimit lines. The newline parsing is done after all other parsing, so it is not possible for arguments (e.g. file names) to contain embedded newline characters. This limitation will likely go away in a future version of SCons.

### Scanner Objects

You can use the Scanner function to define objects to scan new file types for implicit dependencies. Scanner accepts the following arguments:

function
  This can be either: 1) a Python function that will process the Node (file) and return a list of strings (file names) representing the implicit dependencies found in the contents; or: 2) a dictionary that maps keys (typically the file suffix, but see below for more discussion) to other Scanners that should be called.

  If the argument is actually a Python function, the function must take three or four arguments:

  def scanner_function(node, env, path):

  def scanner_function(node, env, path, arg=None):

  The node argument is the internal SCons node representing the file. Use str(node) to fetch the name of the file, and node.get_contents() to fetch contents of the file. Note that the file is not guaranteed to exist before the scanner is called, so the scanner function should check that if there's any chance that the scanned file might not exist (for example, if it's built from other files).

  The env argument is the construction environment for the scan. Fetch values from it using the env.Dictionary() method.

  The path argument is a tuple (or list) of directories that can be searched for files. This will usually be the tuple returned by the path_function argument (see below).

  The arg argument is the argument supplied when the scanner was created, if any.

name
  The name of the Scanner. This is mainly used to identify the Scanner internally.

argument
  An optional argument that, if specified, will be passed to the scanner function (described above) and the path function (specified below).

skeys
  An optional list that can be used to determine which scanner should be used for a given Node. In the usual case of scanning for file names, this argument will be a list of suffixes for the different file types that this Scanner knows how to scan. If the argument is a string, then it will be expanded into a list by the current environment.

path_function
  A Python function that takes four or five arguments: a construction environment, a Node for the directory containing the SConscript file in which the first target was defined, a list of target nodes, a list of source nodes, and an optional argument supplied when the scanner was created. The path_function returns a tuple of directories that can be searched for files to be returned by this Scanner object. (Note that the FindPathDirs() function can be used to return a ready-made path_function for a given construction variable name, instead of having to write your own function from scratch.)

node_class
  The class of Node that should be returned by this Scanner object. Any strings or other objects returned by the scanner function that are not of this class will be run through the node_factory function.

node_factory
  A Python function that will take a string or other object and turn it into the appropriate class of Node to be returned by this Scanner object.

scan_check
  An optional Python function that takes two arguments, a Node (file) and a construction environment, and returns whether the Node should, in fact, be scanned for dependencies. This check can be used to eliminate unnecessary calls to the scanner function when, for example, the underlying file represented by a Node does not yet exist.

recursive
  An optional flag that specifies whether this scanner should be re-invoked on the dependency files returned by the scanner. When this flag is not set, the Node subsystem will only invoke the scanner on the file being scanned, and not (for example) also on the files specified by the #include lines in the file being scanned. recursive may be a callable function, in which case it will be called with a list of Nodes found and should return a list of Nodes that should be scanned recursively; this can be used to select a specific subset of Nodes for additional scanning.

  Note that scons has a global SourceFileScanner object that is used by the Object(), SharedObject(), and StaticObject() builders to decide which scanner should be used for different file extensions. You can using the SourceFileScanner.add_scanner() method to add your own Scanner object to the scons infrastructure that builds target programs or libraries from a list of source files of different types:

        def xyz_scan(node, env, path):
            contents = node.get_contents()
            # Scan the contents and return the included files.

        XYZScanner = Scanner(xyz_scan)

        SourceFileScanner.add_scanner('.xyx', XYZScanner)

        env.Program('my_prog', ['file1.c', 'file2.f', 'file3.xyz'])

## SYSTEM-SPECIFIC BEHAVIOR

SCons and its configuration files are very portable, due largely to its implementation in Python. There are, however, a few portability issues waiting to trap the unwary.

### .C file suffix

SCons handles the upper-case .C file suffix differently, depending on the capabilities of the underlying system. On a case-sensitive system such as Linux or UNIX, SCons treats a file with a .C suffix as a C++ source file. On a case-insensitive system such as Windows, SCons treats a file with a .C suffix as a C source file.

### .F file suffix

SCons handles the upper-case .F file suffix differently, depending on the capabilities of the underlying system. On a case-sensitive system such as Linux or UNIX, SCons treats a file with a .F suffix as a Fortran source file that is to be first run through the standard C preprocessor. On a case-insensitive system such as Windows, SCons treats a file with a .F suffix as a Fortran source file that should not be run through the C preprocessor.

### Windows: Cygwin Tools and Cygwin Python vs. Windows Pythons

Cygwin supplies a set of tools and utilities that let users work on a Windows system using a more POSIX-like environment. The Cygwin tools, including Cygwin Python, do this, in part, by sharing an ability to interpret UNIX-like path names. For example, the Cygwin tools will internally translate a Cygwin path name like /cygdrive/c/mydir to an equivalent Windows pathname of C:/mydir (equivalent to C:\mydir).

Versions of Python that are built for native Windows execution, such as the python.org and ActiveState versions, do not have the Cygwin path name semantics. This means that using a native Windows version of Python to build compiled programs using Cygwin tools (such as gcc, bison, and flex) may yield unpredictable results. "Mixing and matching" in this way can be made to work, but it requires careful attention to the use of path names in your SConscript files.

In practice, users can sidestep the issue by adopting the following rules: When using gcc, use the Cygwin-supplied Python interpreter to run SCons; when using Microsoft Visual C/C++ (or some other Windows compiler) use the python.org or ActiveState version of Python to run SCons.

### Windows: scons.bat file

On Windows systems, SCons is executed via a wrapper scons.bat file. This has (at least) two ramifications:

First, Windows command-line users that want to use variable assignment on the command line may have to put double quotes around the assignments:

      scons "FOO=BAR" "BAZ=BLEH"

Second, the Cygwin shell does not recognize this file as being the same as an scons command issued at the command-line prompt. You can work around this either by executing scons.bat from the Cygwin command line, or by creating a wrapper shell script named scons .

### MinGW

The MinGW bin directory must be in your PATH environment variable or the PATH variable under the ENV construction variable for SCons to detect and use the MinGW tools. When running under the native Windows Python interpreter, SCons will prefer the MinGW tools over the Cygwin tools, if they are both installed, regardless of the order of the bin directories in the PATH variable. If you have both MSVC and MinGW installed and you want to use MinGW instead of MSVC, then you must explictly tell SCons to use MinGW by passing

      tools=['mingw']

to the Environment() function, because SCons will prefer the MSVC tools over the MinGW tools.

## EXAMPLES

To help you get started using SCons, this section contains a brief overview of some common tasks.

### Basic Compilation From a Single Source File

      env = Environment()
      env.Program(target = 'foo', source = 'foo.c')

Note: Build the file by specifying the target as an argument ("scons foo" or "scons foo.exe"). or by specifying a dot ("scons .").

### Basic Compilation From Multiple Source Files

      env = Environment()
      env.Program(target = 'foo', source = Split('f1.c f2.c f3.c'))

### Setting a Compilation Flag

      env = Environment(CCFLAGS = '-g')
      env.Program(target = 'foo', source = 'foo.c')

### Search The Local Directory For .h Files

Note: You do not need to set CCFLAGS to specify -I options by hand. SCons will construct the right -I options from CPPPATH.

      env = Environment(CPPPATH = ['.'])
      env.Program(target = 'foo', source = 'foo.c')

### Search Multiple Directories For .h Files

      env = Environment(CPPPATH = ['include1', 'include2'])
      env.Program(target = 'foo', source = 'foo.c')

### Building a Static Library

      env = Environment()
      env.StaticLibrary(target = 'foo', source = Split('l1.c l2.c'))
      env.StaticLibrary(target = 'bar', source = ['l3.c', 'l4.c'])

### Building a Shared Library

      env = Environment()
      env.SharedLibrary(target = 'foo', source = ['l5.c', 'l6.c'])
      env.SharedLibrary(target = 'bar', source = Split('l7.c l8.c'))

### Linking a Local Library Into a Program

      env = Environment(LIBS = 'mylib', LIBPATH = ['.'])
      env.Library(target = 'mylib', source = Split('l1.c l2.c'))
      env.Program(target = 'prog', source = ['p1.c', 'p2.c'])

### Defining Your Own Builder Object

Notice that when you invoke the Builder, you can leave off the target file suffix, and SCons will add it automatically.

      bld = Builder(action = 'pdftex < $SOURCES > $TARGET'
                    suffix = '.pdf',
                    src_suffix = '.tex')
      env = Environment(BUILDERS = {'PDFBuilder' : bld})
      env.PDFBuilder(target = 'foo.pdf', source = 'foo.tex')

      # The following creates "bar.pdf" from "bar.tex"
      env.PDFBuilder(target = 'bar', source = 'bar')

Note also that the above initialization overwrites the default Builder objects, so the Environment created above can not be used call Builders like env.Program(), env.Object(), env.StaticLibrary(), etc.

### Adding Your Own Builder Object to an Environment

      bld = Builder(action = 'pdftex < $SOURCES > $TARGET'
                    suffix = '.pdf',
                    src_suffix = '.tex')
      env = Environment()
      env.Append(BUILDERS = {'PDFBuilder' : bld})
      env.PDFBuilder(target = 'foo.pdf', source = 'foo.tex')
      env.Program(target = 'bar', source = 'bar.c')

You also can use other Pythonic techniques to add to the BUILDERS construction variable, such as:

      env = Environment()
      env['BUILDERS]['PDFBuilder'] = bld

### Defining Your Own Scanner Object

The following example shows an extremely simple scanner (the kfile_scan() function) that doesn't use a search path at all and simply returns the file names present on any include lines in the scanned file. This would implicitly assume that all included files live in the top-level directory:

      import re

      include_re = re.compile(r'^include\s+(\S+)$', re.M)

      def kfile_scan(node, env, path, arg):
          contents = node.get_contents()
          includes = include_re.findall(contents)
          return includes

      kscan = Scanner(name = 'kfile',
                      function = kfile_scan,
                      argument = None,
                      skeys = ['.k'])
      scanners = Environment().Dictionary('SCANNERS')
      env = Environment(SCANNERS = scanners + [kscan])

      env.Command('foo', 'foo.k', 'kprocess < $SOURCES > $TARGET')

      bar_in = File('bar.in')
      env.Command('bar', bar_in, 'kprocess $SOURCES > $TARGET')
      bar_in.target_scanner = kscan

Here is a similar but more complete example that searches a path of directories (specified as the MYPATH construction variable) for files that actually exist:

      include_re = re.compile(r'^include\s+(\S+)$', re.M)

      def my_scan(node, env, path, arg):
         contents = node.get_contents()
         includes = include_re.findall(contents)
         if includes == []:
              return []
          results = []
          for inc in includes:
              for dir in path:
                  file = dir + os.sep + inc
                  if os.path.exists(file):
                      results.append(file)
                      break
          return results

      scanner = Scanner(name = 'myscanner',
                       function = my_scan,
                       argument = None,
                       skeys = ['.x'],
                       path_function = FindPathDirs('MYPATH'),
                       )
      scanners = Environment().Dictionary('SCANNERS')
      env = Environment(SCANNERS = scanners + [scanner])

The FindPathDirs() function used in the previous example returns a function (actually a callable Python object) that will return a list of directories specified in the $MYPATH construction variable. If you need to customize how the search path is derived, you would provide your own path_function argument when creating the Scanner object, as follows:

      # MYPATH is a list of directories to search for files in
      def pf(env, dir, target, source, arg):
          top_dir = Dir('#').abspath
          results = []
          if env.has_key('MYPATH'):
              for p in env['MYPATH']:
                  results.append(top_dir + os.sep + p)
          return results

      scanner = Scanner(name = 'myscanner',
                       function = my_scan,
                       argument = None,
                       skeys = ['.x'],
                       path_function = pf,
                       )

### Creating a Hierarchical Build

Notice that the file names specified in a subdirectory's SConscript file are relative to that subdirectory.

      SConstruct:

          env = Environment()
          env.Program(target = 'foo', source = 'foo.c')

          SConscript('sub/SConscript')

      sub/SConscript:

          env = Environment()
          # Builds sub/foo from sub/foo.c
          env.Program(target = 'foo', source = 'foo.c')

          SConscript('dir/SConscript')

      sub/dir/SConscript:

          env = Environment()
          # Builds sub/dir/foo from sub/dir/foo.c
          env.Program(target = 'foo', source = 'foo.c')

### Sharing Variables Between SConscript Files

You must explicitly Export() and Import() variables that you want to share between SConscript files.

      SConstruct:

          env = Environment()
          env.Program(target = 'foo', source = 'foo.c')

          Export("env")
          SConscript('subdirectory/SConscript')

      subdirectory/SConscript:

          Import("env")
          env.Program(target = 'foo', source = 'foo.c')

### Building Multiple Variants From the Same Source

Use the variant_dir keyword argument to the SConscript function to establish one or more separate variant build directory trees for a given source directory:

      SConstruct:

          cppdefines = ['FOO']
          Export("cppdefines")
          SConscript('src/SConscript', variant_dir='foo')

          cppdefines = ['BAR']
          Export("cppdefines")
          SConscript('src/SConscript', variant_dir='bar')

      src/SConscript:

          Import("cppdefines")
          env = Environment(CPPDEFINES = cppdefines)
          env.Program(target = 'src', source = 'src.c')

Note the use of the Export() method to set the "cppdefines" variable to a different value each time we call the SConscript function.

### Hierarchical Build of Two Libraries Linked With a Program

      SConstruct:

          env = Environment(LIBPATH = ['#libA', '#libB'])
          Export('env')
          SConscript('libA/SConscript')
          SConscript('libB/SConscript')
          SConscript('Main/SConscript')

      libA/SConscript:

          Import('env')
          env.Library('a', Split('a1.c a2.c a3.c'))

      libB/SConscript:

          Import('env')
          env.Library('b', Split('b1.c b2.c b3.c'))

      Main/SConscript:

          Import('env')
          e = env.Copy(LIBS = ['a', 'b'])
          e.Program('foo', Split('m1.c m2.c m3.c'))

The '#' in the LIBPATH directories specify that they're relative to the top-level directory, so they don't turn into "Main/libA" when they're used in Main/SConscript.

Specifying only 'a' and 'b' for the library names allows SCons to append the appropriate library prefix and suffix for the current platform (for example, 'liba.a' on POSIX systems,

### Customizing construction variables from the command line.

The following would allow the C compiler to be specified on the command line or in the file custom.py.

      opts = Options('custom.py')
      opts.Add('CC', 'The C compiler.')
      env = Environment(options=opts)
      Help(opts.GenerateHelpText(env))

The user could specify the C compiler on the command line:

      scons "CC=my_cc"

or in the custom.py file:

      CC = 'my_cc'

or get documentation on the options:

      $ scons -h

      CC: The C compiler.
          default: None
          actual: cc

### Using Microsoft Visual C++ precompiled headers

Since windows.h includes everything and the kitchen sink, it can take quite some time to compile it over and over again for a bunch of object files, so Microsoft provides a mechanism to compile a set of headers once and then include the previously compiled headers in any object file. This technology is called precompiled headers. The general recipe is to create a file named "StdAfx.cpp" that includes a single header named "StdAfx.h", and then include every header you want to precompile in "StdAfx.h", and finally include "StdAfx.h" as the first header in all the source files you are compiling to object files. For example:

StdAfx.h:

      #include <windows.h>
      #include <my_big_header.h>

StdAfx.cpp:

      #include <StdAfx.h>

Foo.cpp:

      #include <StdAfx.h>

      /* do some stuff */

Bar.cpp:

      #include <StdAfx.h>

      /* do some other stuff */

SConstruct:

      env=Environment()
      env['PCHSTOP'] = 'StdAfx.h'
      env['PCH'] = env.PCH('StdAfx.cpp')[0]
      env.Program('MyApp', ['Foo.cpp', 'Bar.cpp'])

For more information see the document for the PCH builder, and the PCH and PCHSTOP construction variables. To learn about the details of precompiled headers consult the MSDN documention for /Yc, /Yu, and /Yp.

### Using Microsoft Visual C++ external debugging information

Since including debugging information in programs and shared libraries can cause their size to increase significantly, Microsoft provides a mechanism for including the debugging information in an external file called a PDB file. SCons supports PDB files through the PDB construction variable.

SConstruct:

      env=Environment()
      env['PDB'] = 'MyApp.pdb'
      env.Program('MyApp', ['Foo.cpp', 'Bar.cpp'])

For more information see the document for the PDB construction variable.

## ENVIRONMENT

SCONS_LIB_DIR
  Specifies the directory that contains the SCons Python module directory (e.g. /home/aroach/scons-src-0.01/src/engine).

SCONSFLAGS
  A string of options that will be used by scons in addition to those passed on the command line.

## SEE ALSO

scons User Manual, scons Design Document, scons source code.

## AUTHORS

Steven Knight <knight@baldmt.com>
Anthony Roach <aroach@electriceyeball.com>

## Index

NAME
SYNOPSIS
DESCRIPTION
OPTIONS
CONFIGURATION FILE REFERENCE
  Construction Environments
  Builder Methods
  Methods and Functions to Do Things
  SConscript Variables
  Construction Variables
  Configure Contexts
  Construction Variable Options
  File and Directory Nodes
EXTENDING SCONS
  Builder Objects
  Action Objects
  Miscellaneous Action Functions
  Variable Substitution
  Python Code Substitution
  Scanner Objects
SYSTEM-SPECIFIC BEHAVIOR
  .C file suffix
  .F file suffix
  Windows: Cygwin Tools and Cygwin Python vs. Windows Pythons
  Windows: scons.bat file
  MinGW
EXAMPLES
  Basic Compilation From a Single Source File
  Basic Compilation From Multiple Source Files
  Setting a Compilation Flag
  Search The Local Directory For .h Files
  Search Multiple Directories For .h Files
  Building a Static Library
  Building a Shared Library
  Linking a Local Library Into a Program
  Defining Your Own Builder Object
  Adding Your Own Builder Object to an Environment
  Defining Your Own Scanner Object
  Creating a Hierarchical Build
  Sharing Variables Between SConscript Files
  Building Multiple Variants From the Same Source
  Hierarchical Build of Two Libraries Linked With a Program
  Customizing construction variables from the command line.
  Using Microsoft Visual C++ precompiled headers
  Using Microsoft Visual C++ external debugging information
ENVIRONMENT
SEE ALSO
AUTHORS

This document was created by man2html, using the manual pages.
Time: 19:55:43 GMT, March 31, 2008