GOLF(2gg)

NAME
if-defined - (program-flow)

PURPOSE
Conditional compilation.

SYNTAX

        if-defined <symbol>
            <any code>
        end-defined

        if-defined <symbol> [ equal | not-equal | lesser-than | lesser-equal | greater-than | greater-equal ] <number>
            <any code>
        end-defined

        if-not-defined <symbol>
            <any code>
        end-defined

DESCRIPTION
Without a comparison clause, if-defined will cause <any code> to be compiled if <symbol> is defined (see "--cflag" option in gg); if <symbol> is not defined, then <any code> is not compiled.

With a comparison clause, if-defined will cause <any code> to be compiled if <symbol> is equal/not equal/lesser than/lesser or equal/greater than/greater or equal than <number> constant, depending on the clause used (see "--cflag" option in gg). If <symbol> is not defined, then its value is assumed to be 0, and <any code> may still be compiled if the comparison clause and the <number> are such that the condition is true for <symbol> being 0.

if-not-defined will cause <any code> to be compiled if <symbol> is not defined (see "--cflag" option in gg); if <symbol> is defined, then <any code> is not compiled.

Note that <symbol> can start with an underscore, unlike Golf variable names; this is because defined symbols aren't variables and generally are set by the outside environment or during compilation (see "--cflag" option in gg).

EXAMPLES
The following code will have a different output depending on how is the application compiled:

        if-defined DEF1
            @Defined
        end-defined
        if-not-defined DEF1
            @Not defined
        end-defined
        if-defined DEF2 equal 10
            @DEF2 is 10
        end-defined
        if-defined DEF2 equal 0
            @DEF2 is 0
        end-defined

If compiled with:

        gg -q

then the output is:

        Not defined
        DEF2 is 0

If compiled with:

        gg -q --cflag="-DDEF1 -DDEF2=10"

then the output is:

        Defined
        DEF2 is 10

SEE ALSO
 Program flow

break-loop call-handler code-blocks continue-loop do-once exit-handler if-defined if-true quit-process return-handler start-loop See all documentation