make spelling tests pass

[gitmo/MooseX-Storage.git] / lib / MooseX / Storage / Engine / Trait / OnlyWhenBuilt.pm

diff --git a/lib/MooseX/Storage/Engine/Trait/OnlyWhenBuilt.pm b/lib/MooseX/Storage/Engine/Trait/OnlyWhenBuilt.pm
index 163be53..f7f0199 100644 (file)
--- a/lib/MooseX/Storage/Engine/Trait/OnlyWhenBuilt.pm
+++ b/lib/MooseX/Storage/Engine/Trait/OnlyWhenBuilt.pm
@@ -1,7 +1,93 @@
 package MooseX::Storage::Engine::Trait::OnlyWhenBuilt;
 use Moose::Role;
 
-our $VERSION = 1;
+# we should
+# only serialize the attribute if it's already built. So, go ahead
+# and check if the attribute has a predicate. If so, check if it's
+# set  and then go ahead and look it up.
+around 'collapse_attribute' => sub {
+    my ($orig, $self, $attr, @args) = @_;
+
+    my $pred = $attr->predicate if $attr->has_predicate;
+    if ($pred) {
+        return () unless $self->object->$pred();
+    }
+
+    return $self->$orig($attr, @args);
+};
 
 1;
 
+__END__
+
+=pod
+
+=head1 NAME
+
+MooseX::Storage::Engine::Trait::OnlyWhenBuilt - An engine 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
+(i.e., where the predicate returns 'true') will be serialized.
+This avoids any potentially expensive computations.
+
+This trait is applied to an instance of L<MooseX::Storage::Engine>, for the
+user-visible version shown in the SYNOPSIS, see L<MooseX::Storage::Traits::OnlyWhenBuilt>
+
+=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
+