MooseX::Clone - Fine-grained cloning support for Moose objects.


version 0.06


    package Bar;
    use Moose;

    with qw(MooseX::Clone);

    has foo => (
        isa => "Foo",
        traits => [qw(Clone)], # this attribute will be recursively cloned

    package Foo;
    use Moose;

    # this API is used/provided by MooseX::Clone
    sub clone {
        my ( $self, %params ) = @_;

        # ...

    # used like this:

    my $bar = Bar->new( foo => Foo->new );

    my $copy = $bar->clone( foo => [ qw(Args for Foo::clone) ] );


Out of the box Moose only provides very barebones cloning support in order to maximize flexibility.

This role provides a clone method that makes use of the low level cloning support already in Moose and adds selective deep cloning based on introspection on top of that. Attributes with the Clone trait will handle cloning of data within the object, typically delegating to the attribute value's own clone method.



By default Moose objects are cloned like this:

    bless { %$old }, ref $old;

By specifying the Clone trait for certain attributes custom behavior the value's own clone method will be invoked.

By extending this trait you can create custom cloning for certain attributes.

By creating clone methods for your objects (e.g. by composing MooseX::Compile) you can make them interact with this trait.


Specifies attributes that should be skipped entirely while cloning.


clone %params

Returns a clone of the object.

All attributes which do the MooseX::Clone::Meta::Attribute::Trait::Clone role will handle cloning of that attribute. All other fields are plainly copied over, just like in "clone_object" in Class::MOP::Class.

Attributes whose init_arg is in %params and who do the Clone trait will get that argument passed to the clone method (dereferenced). If the attribute does not self-clone then the param is used normally by "clone_object" in Class::MOP::Class, that is it will simply shadow the previous value, and does not have to be an array or hash reference.


Refactor to work in term of a metaclass trait so that meta->clone_object will still do the right thing.


clkao made the food required to write this module


יובל קוג'מן (Yuval Kogman) <>


This software is copyright (c) 2008 by יובל קוג'מן (Yuval Kogman).

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