#!/usr/bin/perl -c
package constant::boolean;
=head1 NAME
constant::boolean - Define TRUE and FALSE constants.
=head1 SYNOPSIS
use constant::boolean;
use File::Spec;
sub is_package_exist {
my ($package) = @_;
return FALSE unless defined $package;
foreach my $inc (@INC) {
my $filename = File::Spec->catfile(
split( /\//, $inc ), split( /\::/, $package )
) . '.pm';
return TRUE if -f $filename;
};
return FALSE;
};
no constant::boolean;
=head1 DESCRIPTION
Defines C and C constants in caller's namespace. You could use
simple values like empty string or zero for false, or any non-empty and
non-zero string value as true, but the C and C constants are more
descriptive.
It is virtually the same as:
# double "not" operator is used for converting scalar to boolean value
use constant TRUE => !! 1;
use constant FALSE => !! '';
The constants exported by C are not reported by
L, so it is more convenient to use this module than to
define C and C constants by yourself.
The constants can be removed from class API with C
pragma or some universal tool like L.
=for readme stop
=cut
use 5.006;
use strict;
use warnings;
our $VERSION = '0.02';
sub import {
my $caller = caller;
no strict 'refs';
# double "not" operator is used for converting scalar to boolean value
*{"${caller}::TRUE"} = sub () { !! 1 };
*{"${caller}::FALSE"} = sub () { !! '' };
return 1;
};
sub unimport {
require Symbol::Util;
my $caller = caller;
Symbol::Util::delete_sub("${caller}::$_") foreach qw( TRUE FALSE );
return 1;
};
1;
=head1 BUGS
If you find the bug or want to implement new features, please report it at
L
=for readme continue
=head1 AUTHOR
Piotr Roszatycki
=head1 LICENSE
Copyright 2008, 2009 by Piotr Roszatycki .
This program is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
See L
