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package Amazon::MWS::Enumeration;

use strict;
use warnings;

use Exporter;

use overload (
    '""'  => \&as_string,
    'cmp' => sub { "$_[0]" cmp $_[1] },
);

sub as_string { 
    my $self = shift; 
    return $$self;
}

sub define {
    my $class = shift;
    no strict 'refs';

    *{"${class}::import"} = *Exporter::import;

    foreach my $const (@_) {
        my $string = $const;
        my $ref    = \$string;
        bless $ref, $class;

        *{"${class}::$const"} = sub { $ref };
        push @{"${class}::EXPORT_OK"}, $const;
        push @{ ${"${class}::EXPORT_TAGS"}{'all'} }, $const;
    }
}

1;

__END__

=head1 NAME

Amazon::MWS::Enumeration

=head1 DESCRIPTION

Base class for enumeration values that stringify to themselves, used to
represent the various enum values defined in the MWS api.  Using these instead
of just raw strings buys you compile-time checking to make sure you didn't
misspell the rather long all-caps names.

=head1 SYNOPSIS

use Amazon::MWS::Enumeration::FeedType qw(:all);

_POST_PRODUCT_DATA_ # no warnings or strict violations, checked for typos!

=head1 METHODS

=head2 define ( @constants )

For each string passed, installs a class method / exportable sub into the
calling subclass by that name.  The value returned by that sub will be an
object blessed into the calling package which stringifies into the constant
itself, e.g. $class->CONSTANT eq 'CONSTANT';

=head2 as_string ()

The stringifier for these enums - simply dereferences the blessed scalar.

=head1 AUTHOR

Paul Driver C<< frodwith@cpan.org >>

=head1 LICENCE AND COPYRIGHT

Copyright (c) 2009, Plain Black Corporation L<http://plainblack.com>.
All rights reserved

This module is free software; you can redistribute it and/or modify it under
the same terms as Perl itself.  See L<perlartistic>.