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MooseX::Clone(3pm) User Contributed Perl Documentation MooseX::Clone(3pm)


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.


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


XXXX XXX'XX (Yuval Kogman) <>


This software is copyright (c) 2008 by XXXX XXX'XX (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.

2015-09-12 perl v5.20.2