MooX::Role::CloneSet - create updated copies of immutable objects


    package Someone;

    use Moo;
    with 'MooX::Role::CloneSet';

    has name => (
        is => 'ro',

    has race => (
        is => 'ro',

    package main;

    my $first = Someone->new(name => 'Drizzt', race => 'drow');

    my $hybrid = $first->cset(race => 'dwarf');

    my $final = $weird->cset(name => 'Catti-brie', race => 'human');


MooX::Role::CloneSet is a role for immutable objects, providing an easy way to create a new object with some modified properties. It provides the cset() method that creates a new object with the specified changes, shallowly copying all the rest of the original object's properties.


  • cset(field => value, ...)

    Shallowly clone the object, making the specified changes to its attributes.

    Note that this method obtains the names and values of the current attributes by dereferencing the object as a hash reference; since Moo does not provide metaclasses by default, it cannot really get to them in any other way. This will not work for parameters that declare an init_arg; see MooX::Role::CloneSet::BuildArgs for an alternative if using truly immutable objects.


Copyright (C) 2016 Peter Pentchev <>

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


Peter Pentchev <>