'\"
'\" Generated from file 'pluginmgr\&.man' by tcllib/doctools with format 'nroff'
'\" Copyright (c) 2005 Andreas Kupries <andreas_kupries@users\&.sourceforge\&.net>
'\"
.TH "pluginmgr" n 0\&.3 tcllib "Plugin management"
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.SH "STANDARD OPTIONS"
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Command-Line Name:	\\fB\\$1\\fR
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.BS
.SH NAME
pluginmgr \- Manage a plugin
.SH SYNOPSIS
package require \fBTcl  8\&.4\fR
.sp
package require \fBpluginmgr  ?0\&.3?\fR
.sp
\fB::pluginmgr\fR \fIobjectName\fR ?\fIoption value\fR\&.\&.\&.?
.sp
\fB::pluginmgr::paths\fR \fIobjectName\fR \fIname\fR\&.\&.\&.
.sp
\fBobjectName\fR \fBmethod\fR ?\fIarg arg \&.\&.\&.\fR?
.sp
\fIobjectName\fR \fBclone\fR
.sp
\fIobjectName\fR \fBconfigure\fR
.sp
\fIobjectName\fR \fBconfigure\fR \fIoption\fR
.sp
\fIobjectName\fR \fBconfigure\fR \fB-option\fR \fIvalue\fR\&.\&.\&.
.sp
\fIobjectName\fR \fBcget\fR \fB-option\fR
.sp
\fIobjectName\fR \fBdestroy\fR
.sp
\fIobjectName\fR \fBdo\fR \fIarg\fR\&.\&.\&.
.sp
\fIobjectName\fR \fBinterpreter\fR
.sp
\fIobjectName\fR \fBplugin\fR
.sp
\fIobjectName\fR \fBload\fR \fIstring\fR
.sp
\fIobjectName\fR \fBunload\fR
.sp
\fIobjectName\fR \fBlist\fR
.sp
\fIobjectName\fR \fBpath\fR \fIpath\fR
.sp
\fIobjectName\fR \fBpaths\fR
.sp
.BE
.SH DESCRIPTION
This package provides commands and objects for the generic management
of plugins which can be loaded into an application\&.
.PP
To avoid the implementation of yet another system to locate Tcl code
the system provides by this package is built on top of the regular
package management system\&. Each plugin is considered as a package and
a simple invokation of \fBpackage require\fR is enough to locate and
load it, if it exists\&. The only time we will need additional paths is
when a plugin manager is part of a wrapped application and has to be
able to search for plugins existing outside of that application\&. For
this situation the package provides a command to create a general set
of such paths based on names for the plugin manager and/or application
in question\&.
.PP
The main contribution of this package is a generic framework which
allows the easy declaration of
.IP [1]
How to translate a plugin name to the name of the package implementing
it, and vice versa\&.
.IP [2]
The list of commands a plugin has to provide as API, and also of more
complex checks as code\&.
.IP [3]
The list of commands expected by the plugin from the environment\&.
.PP
This then allows the easy generation of plugin managers customized to
particular types of plugins for an application\&.
.PP
It should be noted that all plugin code is considered untrusted and
will always be executed within a safe interpreter\&. The interpreter is
enabled enough to allow plugins the loading of all additional packages
they may need\&.
.SH "PUBLIC API"
.SS "PACKAGE COMMANDS"
.TP
\fB::pluginmgr\fR \fIobjectName\fR ?\fIoption value\fR\&.\&.\&.?
This command creates a new plugin manager object with an associated
Tcl command whose name is \fIobjectName\fR\&. This \fIobject\fR command
is explained in full detail in the sections \fBOBJECT COMMAND\fR
and \fBOBJECT METHODS\fR\&. The object command will be created
under the current namespace if the \fIobjectName\fR is not fully
qualified, and in the specified namespace otherwise\&.
.sp
The options and their values coming after the name of the object are
used to set the initial configuration of the mamager object,
specifying the applicable plugins and their API\&.
.TP
\fB::pluginmgr::paths\fR \fIobjectName\fR \fIname\fR\&.\&.\&.
This utility command adds a set of paths to the specified object,
based on the given \fIname\fRs\&.
It will search for:
.RS
.IP [1]
The environment variable \fB\fIname\fR_PLUGINS\fR\&. Its contents will
be interpreted as a list of package paths\&. The entries have to be
separated by either \fB:\fR (unix) or \fB;\fR (windows)\&.
.sp
The name will be converted to upper-case letters\&.
.IP [2]
The registry entry "HKEY_LOCAL_MACHINE\\SOFTWARE\\\fIname\fR\\PLUGINS"\&.
Its contents will be interpreted as a list of package paths\&. The
entries have to be separated by \fB;\fR\&. This item is considered
only when on Windows (tm)\&.
.sp
The casing of letters is not changed\&.
.IP [3]
The registry entry "HKEY_CURRENT_USER\\SOFTWARE\\\fIname\fR\\PLUGINS"\&.
Its contents will be interpreted as a list of package paths\&. The
entries have to be separated by \fB;\fR\&. This item is considered
only when on Windows (tm)\&.
.sp
The casing of letters is not changed\&.
.IP [4]
The directory "\fI~/\&.\fIname\fR/plugin\fR"\&.
.IP [5]
The directory "\fI~/\&.\fIname\fR/plugins\fR"\&.
.sp
The casing of letters is not changed\&.
.RE
.sp
and add all the paths found that way to the list of package paths
maintained by the object\&.
.sp
If \fIname\fR is namespaced each item in the list will be repeated per
prefix of \fIname\fR, with conversion of :-sequences into the proper
separator (underscore for environment variables, backslash for
registry entries, and / for directories)\&.
.sp
Examples:
.sp
.CS


    ::pluginmgr::paths ::obj docidx

    => env  DOCIDX_PLUGINS
       reg  HKEY_LOCAL_MACHINE\\SOFTWARE\\docidx\\PLUGINS
       reg  HKEY_CURRENT_USER\\SOFTWARE\\docidx\\PLUGINS
       path ~/\&.docidx/plugins

    ::pluginmgr::paths ::obj doctools::idx

    => env  DOCTOOLS_PLUGINS
       env  DOCTOOLS_IDX_PLUGINS
       reg  HKEY_LOCAL_MACHINE\\SOFTWARE\\doctools\\PLUGINS
       reg  HKEY_LOCAL_MACHINE\\SOFTWARE\\doctools\\idx\\PLUGINS
       reg  HKEY_CURRENT_USER\\SOFTWARE\\doctools\\PLUGINS
       reg  HKEY_CURRENT_USER\\SOFTWARE\\doctools\\idx\\PLUGINS
       path ~/\&.doctools/plugin
       path ~/\&.doctools/idx/plugin

.CE
.PP
.SS "OBJECT COMMAND"
All commands created by the command \fB::pluginmgr\fR (See section
\fBPACKAGE COMMANDS\fR) have the following general form and may
be used to invoke various operations on their plugin manager object\&.
.TP
\fBobjectName\fR \fBmethod\fR ?\fIarg arg \&.\&.\&.\fR?
The method \fBmethod\fR and its \fIarg\fR'uments determine the exact
behavior of the command\&. See section \fBOBJECT METHODS\fR for
the detailed specifications\&.
.PP
.SS "OBJECT METHODS"
.TP
\fIobjectName\fR \fBclone\fR
This method creates a new plugin management object and returns the
associated object command\&. The generated object is a clone of the
object the method was invoked on\&. I\&.e\&. the new object will have the
same configuration as the current object\&. With regard to state, if the
current object has a plugin loaded then this plugin and all associated
state is moved to the generated clone and the current object is reset
into the base state (no plugin loaded)\&. In this manner a configured
plugin manager is also a factory for loaded plugins\&.
.TP
\fIobjectName\fR \fBconfigure\fR
The method returns a list of all known options and their current
values when called without any arguments\&.
.TP
\fIobjectName\fR \fBconfigure\fR \fIoption\fR
The method behaves like the method \fBcget\fR when called with a
single argument and returns the value of the option specified by said
argument\&.
.TP
\fIobjectName\fR \fBconfigure\fR \fB-option\fR \fIvalue\fR\&.\&.\&.
The method reconfigures the specified \fBoption\fRs of the object,
setting them to the associated \fIvalue\fRs, when called with an even
number of arguments, at least two\&.
.sp
The legal options are described in the section
\fBOBJECT CONFIGURATION\fR\&.
.TP
\fIobjectName\fR \fBcget\fR \fB-option\fR
This method expects a legal configuration option as argument and will
return the current value of that option for the object the method was
invoked for\&.
.sp
The legal configuration options are described in section
\fBOBJECT CONFIGURATION\fR\&.
.TP
\fIobjectName\fR \fBdestroy\fR
This method destroys the object it is invoked for\&.
.TP
\fIobjectName\fR \fBdo\fR \fIarg\fR\&.\&.\&.
This method interprets its list of arguments as the words of a command
and invokes this command in the execution context of the plugin\&.
The result of the invoked command is made the result of the method\&.
The call will fail with an error if no valid plugin has been loaded
into the manager object\&.
.TP
\fIobjectName\fR \fBinterpreter\fR
This method returns the handle of the safe interpreter the current
plugin is loaded into\&. An empty string as return value signals that
the manager currently has no valid plugin loaded\&.
.TP
\fIobjectName\fR \fBplugin\fR
This method returns the name of the plugin currently loaded\&. An empty
string as return value signals that the manager currently has no valid
plugin loaded\&.
.TP
\fIobjectName\fR \fBload\fR \fIstring\fR
This method loads, validates, and initializes a named plugin into the
manager object\&.
.sp
The algorithm to locate and load the plugin employed is:
.RS
.IP [1]
If the \fIstring\fR contains the path to an existing file then this
file is taken as the implementation of the plugin\&.
.IP [2]
Otherwise the plugin name is translated into a package name via the value
of the option \fB-pattern\fR and then loaded through the
regular package management\&.
.IP [3]
The load fails\&.
.RE
.sp
The algorithm to validate and initialize the loaded code is:
.RS
.IP [1]
If the option \fB-api\fR is non-empty introspection commands are
used to ascertain that the plugin provides the listed commands\&.
.IP [2]
If the option \fB-check\fR is non-empty the specified command
prefix is called\&.
.IP [3]
If either of the above fails the candidate plugin is unloaded again
.IP [4]
Otherwise all the commands specified via the option
\fB-cmds\fR are installed in the plugin\&.
.RE
.sp
A previously loaded plugin is discarded, but only if the new plugin
was found and sucessfully validated and initialized\&. Note that there
will be no intereference between old and new plugin as both will be
put into separate safe interpreters\&.
.TP
\fIobjectName\fR \fBunload\fR
This method unloads the currently loaded plugin\&. It returns the empty
string\&. The call will be silently ignored if no plugin is loaded at
all\&.
.TP
\fIobjectName\fR \fBlist\fR
This method uses the contents of the option \fB-pattern\fR to find
all packages which can be plugins under the purview of this manager
object\&. It translates their names into plugin names and returns a list
containing them\&.
.TP
\fIobjectName\fR \fBpath\fR \fIpath\fR
This methods adds the specified \fIpath\fR to the list of additional
package paths to look at when searching for a plugin\&. It returns the
empty string\&. Duplicate paths are ignored, i\&.e\&. each path is added
only once\&. Paths are made absolute, but are not normalized\&.
.TP
\fIobjectName\fR \fBpaths\fR
This method returns a list containing all additional paths which have
been added to the plugin manager object since its creation\&.
.PP
.SS "OBJECT CONFIGURATION"
All plugin manager objects understand the following configuration options:
.TP
\fB-pattern\fR \fIstring\fR
The value of this option is a glob pattern which has to contain
exactly one '*'-operator\&. All packages whose names match this pattern
are the plugins recognized by the manager object\&. And vice versa, the
replacement of the '*'-operator with a plugin name will yield the name
of the package implementing that plugin\&.
.sp
This option has no default, except if option \fB-name\fR was set\&.
It has to be set before attempting to load a plugin, either directly,
or through option \fB-name\fR\&.
.TP
\fB-api\fR \fIlist\fR
The value of this option is a list of command names, and any plugin
loaded has to provide these commands\&. Names which are not fully
qualified are considered to be rooted in the global namespace\&.
If empty no expectations are made on the plugin\&. The default value is
the empty list\&.
.TP
\fB-check\fR \fIcmdprefix\fR
The value of this option is interpreted as a command prefix\&.
Its purpose is to perform complex checks on a loaded plugin package to
validate it, which go beyond a simple list of provided commands\&.
.sp
It is called with the manager object command as the only argument and
has to return a boolean value\&. A value of \fBtrue\fR will be
interpreted to mean that the candidate plugin passed the test\&.
The call will happen if and only if the candidate plugin already
passed the basic API check specified through the option \fB-api\fR\&.
.sp
The default value is the empty list, which causes the manager object
to suppress the call and to assume the candidate plugin passes\&.
.TP
\fB-cmds\fR \fIdict\fR
The value of this option is a dictionary\&.  It specifies the commands
which will be made available to the plugin (as keys), and the trusted
commands in the environment which implement them (as values)\&.
The trusted commands will be executed in the interpreter specified by
the option \fB-cmdip\fR\&.
The default value is the empty dictionary\&.
.TP
\fB-cmdip\fR \fIipspec\fR
The value of this option is the path of the interpreter where the
trusted commands given to the plugin will be executed in\&.
The default is the empty string, referring to the current interpreter\&.
.TP
\fB-setup\fR \fIcmdprefix\fR
The value of this option is interpreted as a command prefix\&.
.sp
It is called whenever a new safe interpreter for a plugin has been
created, but before a plugin is loaded\&. It is provided with the
manager object command and the interpreter handle as its only
arguments\&. Any return value will be ignored\&.
.sp
Its purpose is give a user of the plugin management the ability to
define commands, packages, etc\&. a chosen plugin may need while being
loaded\&.
.PP
.SH "BUGS, IDEAS, FEEDBACK"
This document, and the package it describes, will undoubtedly contain
bugs and other problems\&.
Please report such in the category \fIpluginmgr\fR of the
\fITcllib Trackers\fR [http://core\&.tcl\&.tk/tcllib/reportlist]\&.
Please also report any ideas for enhancements you may have for either
package and/or documentation\&.
.SH KEYWORDS
plugin management, plugin search
.SH CATEGORY
Programming tools
.SH COPYRIGHT
.nf
Copyright (c) 2005 Andreas Kupries <andreas_kupries@users\&.sourceforge\&.net>

.fi