NAME
    constant::def - Perl pragma to declare previously undeclared constants

VERSION
    Version 0.01

SYNOPSIS
    Define compile-time constant only if it wasn't previously defined
    elsewhere. The main reason is to use for debugging constants, since
    there is no way to change the value, except by editing the source

        # common way: (redefine may be done only in source file)
        use constant DEBUG => ...;
        # or 
        BEGIN { *DEBUG = sub () { ... } }
        # or 
        sub DEBUG () { ... }

        ################

        # complex way: redefine works, if done before use of module
        # in main.pl
        BEGIN { *My::Module::Debug = sub () { 1 }; }
        use My::Module;

        # in My/Module.pm
        BEGIN { defined &DEBUG or do { my $debug = $ENV{MY_MODULE_DEBUG} || 0; *DEBUG = sub () { $debug } } }

        ################

        # using this distribution
        # redefine works, if done before use of module

        # in main.pl
        use constant::abs 'My::Module::DEBUG' => 1;
        use My::Module;

        # in My/Module.pm
        use constant::def DEBUG => $ENV{MY_MODULE_DEBUG} || 0;

    Syntax is fully compatible with "constant"

SEE ALSO
    constant::abs, constant

AUTHOR
    Mons Anderson, "<mons at cpan.org>"

BUGS
    Please report any bugs or feature requests to "bug-constant-def at
    rt.cpan.org", or through the web interface at
    <http://rt.cpan.org/NoAuth/ReportBug.html?Queue=constant-def>. I will be
    notified, and then you'll automatically be notified of progress on your
    bug as I make changes.

COPYRIGHT & LICENSE
    Copyright 2009 Mons Anderson.

    This program is free software; you can redistribute it and/or modify it
    under the same terms as Perl itself.