package MooseX::Storage::Traits::OnlyWhenBuilt;
# ABSTRACT: A custom trait to bypass serialization

our $VERSION = '0.52';

use Moose::Role;
use namespace::autoclean;

requires 'pack';
requires 'unpack';

around 'pack' => sub {
    my ($orig, $self, %args) = @_;
    $args{engine_traits} ||= [];
    push(@{$args{engine_traits}}, 'OnlyWhenBuilt');
    $self->$orig(%args);
};

around 'unpack' => sub {
    my ($orig, $self, $data, %args) = @_;
    $args{engine_traits} ||= [];
    push(@{$args{engine_traits}}, 'OnlyWhenBuilt');
    $self->$orig($data, %args);
};

no Moose::Role;

1;

__END__

=pod

=encoding UTF-8

=head1 NAME

MooseX::Storage::Traits::OnlyWhenBuilt - A custom trait to bypass serialization

=head1 VERSION

version 0.52

=head1 SYNOPSIS

    {   package Point;
        use Moose;
        use MooseX::Storage;

        with Storage( traits => [qw|OnlyWhenBuilt|] );

        has 'x' => (is => 'rw', lazy_build => 1 );
        has 'y' => (is => 'rw', predicate => '_has_y' );
        has 'z' => (is => 'rw', builder => '_build_z' );

        sub _build_x { 3 }
        sub _build_y { expensive_computation() }
        sub _build_z { 3 }

    }

    my $p = Point->new( 'x' => 4 );

    # the result of ->pack will contain:
    # { x => 4, z => 3 }
    $p->pack;

=head1 DESCRIPTION

Sometimes you don't want a particular attribute to be part of the
serialization if it has not been built yet. If you invoke C<Storage()>
as outlined in the C<Synopsis>, only attributes that have been built
(i.e., where the predicate returns 'true') will be serialized.
This avoids any potentially expensive computations.

=for stopwords culted

See the SYNOPSIS for a nice example that can be easily cargo-culted.

=head1 SUPPORT

Bugs may be submitted through L<the RT bug tracker|https://rt.cpan.org/Public/Dist/Display.html?Name=MooseX-Storage>
(or L<bug-MooseX-Storage@rt.cpan.org|mailto:bug-MooseX-Storage@rt.cpan.org>).

There is also a mailing list available for users of this distribution, at
L<http://lists.perl.org/list/moose.html>.

There is also an irc channel available for users of this distribution, at
L<C<#moose> on C<irc.perl.org>|irc://irc.perl.org/#moose>.

=head1 AUTHORS

=over 4

=item *

Chris Prather <chris.prather@iinteractive.com>

=item *

Stevan Little <stevan.little@iinteractive.com>

=item *

יובל קוג'מן (Yuval Kogman) <nothingmuch@woobling.org>

=back

=head1 COPYRIGHT AND LICENSE

This software is copyright (c) 2007 by Infinity Interactive, Inc.

This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.

=cut
