NAME

       boolean - Boolean support for Perl

VERSION

       This document describes boolean version 0.46.

SYNOPSIS

           use boolean;

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

           do &maybe if boolean($value)->isTrue;

       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".

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 encodedecoderoundtrip
       Boolean values.

FUNCTIONS

       This module defines the following functions:

       "true"
           This function returns a scalar value which will evaluate to true. The value is a
           singleton object, meaning there is only one "true" value in a Perl process at any
           time. You can check to see whether the value is the "true" object with the isTrue
           function described below.

       "false"
           This function returns a scalar value which will evaluate to false. The value is a
           singleton object, meaning there is only one "false" value in a Perl process at any
           time. You can check to see whether the value is the "false" object with the isFalse
           function described below.

       "boolean($scalar)"
           Casts the scalar value to a boolean value. If $scalar is true, it returns
           "boolean::true", otherwise it returns "boolean::false".

       "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.

METHODS

       Since true and false return objects, you can call methods on them.

       "$boolean->isTrue"
           Same as isTrue($boolean).

       "$boolean->isFalse"
           Same as isFalse($boolean).

USE OPTIONS

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

       The module also defines these export tags:

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

DEPRECATIONS

       This module offered an export tag, "-truth", that overrides the Perl interpreter's
       internal values for true and false. This has been found to corrupt the interpreter in some
       circumstances. Also, these overrides will no longer be possible as of Perl 5.22.
       Therefore, the "-truth" import tag is deprecated.

JSON SUPPORT

       JSON::MaybeXS (or less preferably JSON.pm ) will encode Perl data with boolean.pm values
       correctly if you use the "convert_blessed" option:

           use JSON::MaybeXS;
           use boolean -truth;
           my $json = JSON::MaybeXS->new->convert_blessed;
           say $json->encode({false => (0 == 1)});     # Says: '{"false":false}',

AUTHOR

       Ingy döt Net <ingy@cpan.org>

COPYRIGHT AND LICENSE

       Copyright 2007-2016. Ingy döt 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>