
EVAL_STMT  -  controls  the  execution  of  statements  in

expressions

Calling sequence:

EVAL_STMT := bool

Parameter:

bool   --  Boolean value

Summary:

EVAL_STMT controls the execution of statements that occur in expressions;
such as f((a:=b)).  If EVAL_STMT is set to TRUE, then such statements are
executed.  In the example above, firstly b is assigned to a and then f is
called with b as argument. If, however, EVAL_STMT is set to FALSE then the
statements in expressions are not executed.

Through the assignment EVAL_STMT := NIL;, EVAL_STMT is set to its default
value TRUE. EVAL_STMT is an environment variable.

>>  a + (b := 3), b;

     a+3, 3

>>  EVAL_STMT := FALSE: c + (d := 3), d;

     c + (d := 3), d

