package MooseX::Storage::Traits::OnlyWhenBuilt;
use Moose::Role;

our $VERSION   = '0.30';
our $AUTHORITY = 'cpan:STEVAN';

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

=head1 NAME

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

=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', lazy_build => 1 );
        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
(ie, where the predicate returns 'true') will be serialized.
This avoids any potentially expensive computations.

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

=head1 METHODS

=head2 Introspection

=over 4

=item B<meta>

=back

=head1 BUGS

All complex software has bugs lurking in it, and this module is no
exception. If you find a bug please either email me, or add the bug
to cpan-RT.

=head1 AUTHOR

Stevan Little E<lt>stevan.little@iinteractive.comE<gt>

=head1 COPYRIGHT AND LICENSE

Copyright 2007-2008 by Infinity Interactive, Inc.

L<http://www.iinteractive.com>

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

=cut