MooseX::Storage::Engine::Trait::OnlyWhenBuilt - An engine trait to bypass serialization


version 0.53


    {   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 }


Sometimes you don't want a particular attribute to be part of the serialization if it has not been built yet. If you invoke Storage() as outlined in the 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 MooseX::Storage::Engine, for the user-visible version shown in the SYNOPSIS, see MooseX::Storage::Traits::OnlyWhenBuilt


Bugs may be submitted through the RT bug tracker (or

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  • Chris Prather <>

  • Stevan Little <>

  • יובל קוג'מן (Yuval Kogman) <>


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.