/ 
boolean-0.24
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/ boolean

NAME

boolean - Boolean support for Perl

SYNOPSIS

use boolean;

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

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

With autobox:

use autobox;
use boolean;

do &maybe if $value->is_true;

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 encode/decode/roundtrip Boolean values.

FUNCTIONS

This module defines the following functions:

true

This function returns a scalar value which should 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 should 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->is_true

Same as isTrue($boolean).

$boolean->is_false

Same as isFalse($boolean).

autobox Methods

If you use boolean with autobox you can call the following methods on any scalar:

$scalar->boolean

Same as boolean($scalar).

$scalar->is_true

Same as isTrue(boolean($scalar)).

$scalar->is_false

Same as isFalse(boolean($scalar)).

EXPORTABLES

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

:test

Exports isTrue, isFalse, isBoolean

AUTHOR

Ingy döt Net <ingy@cpan.org>

COPYRIGHT

Copyright (c) 2007, 2008, 2010, 2011. 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