1 package Moose::Util::MetaRole;
7 $VERSION = eval $VERSION;
8 our $AUTHORITY = 'cpan:STEVAN';
10 use List::MoreUtils qw( all );
12 my @Classes = qw( constructor_class destructor_class error_class );
14 sub apply_metaclass_roles {
17 my $for = $options{for_class};
19 my %old_classes = map { $_ => Class::MOP::class_of($for)->$_ }
20 grep { Class::MOP::class_of($for)->can($_) }
23 my $meta = _make_new_metaclass( $for, \%options );
25 for my $c ( grep { $meta->can($_) } @Classes ) {
26 if ( $options{ $c . '_roles' } ) {
27 my $class = _make_new_class(
29 $options{ $c . '_roles' }
35 $meta->$c( $old_classes{$c} );
42 sub _make_new_metaclass {
46 return Class::MOP::class_of($for)
47 unless grep { exists $options->{ $_ . '_roles' } }
52 wrapped_method_metaclass
57 = _make_new_class( ref $for->meta(), $options->{metaclass_roles} );
59 my $old_meta = $for->meta();
61 # This could get called for a Moose::Meta::Role as well as a Moose::Meta::Class
63 $_ => _make_new_class( $old_meta->$_(), $options->{ $_ . '_roles' } )
65 grep { $old_meta->can($_) }
69 wrapped_method_metaclass
73 return $new_metaclass->reinitialize( $for, %classes );
76 sub apply_base_class_roles {
79 my $for = $options{for_class};
81 my $meta = $for->meta();
83 my $new_base = _make_new_class(
86 [ $meta->superclasses() ],
89 $meta->superclasses($new_base)
90 if $new_base ne $meta->name();
94 my $existing_class = shift;
96 my $superclasses = shift || [$existing_class];
98 return $existing_class unless $roles;
100 my $meta = Class::MOP::Class->initialize($existing_class);
102 return $existing_class
103 if $meta->can('does_role') && all { $meta->does_role($_) } @{$roles};
105 return Moose::Meta::Class->create_anon_class(
106 superclasses => $superclasses,
118 Moose::Util::MetaRole - Apply roles to any metaclass, as well as the object base class
122 package MyApp::Moose;
129 use Moose::Util::MetaRole;
131 use MyApp::Role::Meta::Class;
132 use MyApp::Role::Meta::Method::Constructor;
133 use MyApp::Role::Object;
135 Moose::Exporter->setup_import_methods( also => 'Moose' );
141 Moose->init_meta(%options);
143 Moose::Util::MetaRole::apply_metaclass_roles(
144 for_class => $options{for_class},
145 metaclass_roles => ['MyApp::Role::Meta::Class'],
146 constructor_class_roles => ['MyApp::Role::Meta::Method::Constructor'],
149 Moose::Util::MetaRole::apply_base_class_roles(
150 for_class => $options{for_class},
151 roles => ['MyApp::Role::Object'],
154 return $options{for_class}->meta();
159 B<The whole concept behind this module is still considered
160 experimental, and it could go away in the future!>
162 This utility module is designed to help authors of Moose extensions
163 write extensions that are able to cooperate with other Moose
164 extensions. To do this, you must write your extensions as roles, which
165 can then be dynamically applied to the caller's metaclasses.
167 This module makes sure to preserve any existing superclasses and roles
168 already set for the meta objects, which means that any number of
169 extensions can apply roles in any order.
173 B<It is very important that you only call this module's functions when
174 your module is imported by the caller>. The process of applying roles
175 to the metaclass reinitializes the metaclass object, which wipes out
176 any existing attributes already defined. However, as long as you do
177 this when your module is imported, the caller should not have any
178 attributes defined yet.
180 The easiest way to ensure that this happens is to use
181 L<Moose::Exporter> and provide an C<init_meta> method that will be
182 called when imported.
186 This module provides two functions.
188 =head2 apply_metaclass_roles( ... )
190 This function will apply roles to one or more metaclasses for the
191 specified class. It accepts the following parameters:
195 =item * for_class => $name
197 This specifies the class for which to alter the meta classes.
199 =item * metaclass_roles => \@roles
201 =item * attribute_metaclass_roles => \@roles
203 =item * method_metaclass_roles => \@roles
205 =item * wrapped_method_metaclass_roles => \@roles
207 =item * instance_metaclass_roles => \@roles
209 =item * constructor_class_roles => \@roles
211 =item * destructor_class_roles => \@roles
213 These parameter all specify one or more roles to be applied to the
214 specified metaclass. You can pass any or all of these parameters at
219 =head2 apply_base_class_roles( for_class => $class, roles => \@roles )
221 This function will apply the specified roles to the object's base class.
225 Dave Rolsky E<lt>autarch@urth.orgE<gt>
227 =head1 COPYRIGHT AND LICENSE
229 Copyright 2009 by Infinity Interactive, Inc.
231 L<http://www.iinteractive.com>
233 This library is free software; you can redistribute it and/or modify
234 it under the same terms as Perl itself.