boolean

SYNOPSIS
           use boolean;

           do &always if true;
           do &never if false;

       and:

           use boolean ':all';

           $guess = int(rand(2)) % 2 ? true : false;

           do &something if isTrue($guess);
           do &something_else if isFalse($guess);

DESCRIPTION
       Most programming languages have a native "Boolean" data type.  Perl
       does not.

       Perl has a simple and well known Truth System. The following scalar
       values are false:

           $false1 = undef;
           $false2 = 0;
           $false3 = 0.0;
           $false4 = '';
           $false5 = '0';

       Every other scalar value is true.

       This module provides basic Boolean support, by defining two special
       objects: "true" and "false".

IMPLEMENTATION NOTE
       Version 0.20 is a complete rewrite from version 0.12. The old version
       used XS and had some fundamental flaws. The new version is pure Perl
       and is more correct. The new version depends on overload.pm to make the
       true and false objects return 1 and 0 respectively.

       The "null" support found in 0.12 was also removed as superfluous.

RATIONALE
       When sharing data between programming languages, it is important to
       support the same group of basic types. In Perlish programming
       languages, these types include: Hash, Array, String, Number, Null and
       Boolean. Perl lacks native Boolean support.

       Data interchange modules like YAML and JSON can now "use boolean" to
       encode/decode/roundtrip Boolean values.

FUNCTIONS
       This module defines the following functions:

           described below.

       isTrue($scalar)
           Returns "boolean::true" if the scalar passed to it is the
           "boolean::true" object. Returns "boolean::false" otherwise.

       isFalse($scalar)
           Returns "boolean::true" if the scalar passed to it is the
           "boolean::false" object. Returns "boolean::false" otherwise.

       isBoolean($scalar)
           Returns "boolean::true" if the scalar passed to it is the
           "boolean::true" or "boolean::false" object. Returns
           "boolean::false" otherwise.

EXPORTABLES
       By default this module exports the "true" and "false" functions.

       The module also defines these export tags:

       :all
           Exports "true", "false", "isTrue", "isFalse", "isBoolean"

       :test
           Exports "isTrue", "isFalse", "isBoolean"

AUTHOR
       Ingy doet Net <ingy@cpan.org>

COPYRIGHT
       Copyright (c) 2007, 2008. Ingy doet Net.

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

       See http://www.perl.com/perl/misc/Artistic.html



perl v5.10.0                      2008-08-25                      boolean(3pm)