true(3pm) [debian man page]

true(3pm)						User Contributed Perl Documentation						 true(3pm)

NAME

       true - automatically return a true value when a file is required

SYNOPSIS

	 package Contemporary::Perl;

	 use strict;
	 use warnings;
	 use true;

	 sub import {
	     strict->import();
	     warnings->import();
	     true->import();
	 }

DESCRIPTION

       Perl's "require" builtin (and its "use" wrapper) requires the files it loads to return a true value.  This is usually accomplished by
       placing a single

	   1;

       statement at the end of included scripts or modules. It's not onerous to add but it's a speed bump on the Perl novice's road to
       enlightenment. In addition, it appears to be a non-sequitur to the uninitiated, leading some to attempt to mitigate its appearance with a
       comment:

	   1; # keep require happy

       or:

	   1; # Do not remove this line

       or even:

	   1; # Must end with this, because Perl is bogus.

       This module packages this "return true" behaviour so that it need not be written explicitly.  It can be used directly, but it is intended
       to be invoked from the "import" method of a Modern::Perl-style module that enables modern Perl features and conveniences and cleans up
       legacy Perl warts.

   METHODS
       "true" is file-scoped rather than lexically-scoped. Importing it anywhere in a file (e.g. at the top-level or in a nested scope) causes
       that file to return true, and unimporting it anywhere in a file restores the default behaviour. Redundant imports/unimports are ignored.

       import

       Enable the "automatically return true" behaviour for the currently-compiling file. This should typically be invoked from the "import"
       method of a module that loads "true". Code that uses this module solely on behalf of its callers can load "true" without importing it e.g.

	   use true (); # don't import

	   sub import {
	       true->import();
	   }

	   1;

       But there's nothing stopping a wrapper module also importing "true" to obviate its own need to explicitly return a true value:

	   use true; # both load and import it

	   sub import {
	       true->import();
	   }

	   # no need to return true

       unimport

       Disable the "automatically return true" behaviour for the currently-compiling file.

   EXPORT
       None by default.

NOTES

       Because some versions of YAML::XS may interpret the key of "true" as a boolean, you may have trouble declaring a dependency on true.pm.
       You can work around this by declaring a dependency on the package true::VERSION, which has the same version as true.pm.

SEE ALSO

       o   latest

       o   Modern::Perl

       o   nonsense

       o   perl5i

       o   Toolkit

       o   uni::perl

AUTHOR

       chocolateboy, <chocolate@cpan.org>

COPYRIGHT AND LICENSE

       Copyright (C) 2010-2011 by chocolateboy

       This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.10.0 or,
       at your option, any later version of Perl 5 you may have available.

perl v5.14.2							    2011-04-18								 true(3pm)

boolean(3pm)						User Contributed Perl Documentation					      boolean(3pm)

NAME

       boolean - Boolean support for Perl

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);

       and:

	   use boolean -truth;

	   die unless ref(42 == 42) eq 'boolean';
	   die unless ("foo" =~ /bar/) eq '0';

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 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"

   -truth
       You can specify the "-truth" option to override truth operators to return "boolean" values.

	   use boolean -truth;
	   print ref("hello" eq "world"), "
";

       Prints:

	   boolean

       "-truth" can be used with the other import options.

AUTHOR

       Ingy doet Net <ingy@cpan.org>

COPYRIGHT

       Copyright (c) 2007, 2008, 2010, 2011. 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 v5.12.4							    2011-09-12							      boolean(3pm)