1 package Moose::Util::MetaRole;
6 our $VERSION = '0.89_01';
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
54 application_to_class_class
55 application_to_role_class
56 application_to_instance_class
59 my $old_meta = Class::MOP::class_of($for);
61 = _make_new_class( ref $old_meta, $options->{metaclass_roles} );
63 # This could get called for a Moose::Meta::Role as well as a Moose::Meta::Class
65 $_ => _make_new_class( $old_meta->$_(), $options->{ $_ . '_roles' } )
67 grep { $old_meta->can($_) }
71 wrapped_method_metaclass
73 application_to_class_class
74 application_to_role_class
75 application_to_instance_class
78 return $new_metaclass->reinitialize( $for, %classes );
81 sub apply_base_class_roles {
84 my $for = $options{for_class};
86 my $meta = Class::MOP::class_of($for);
88 my $new_base = _make_new_class(
91 [ $meta->superclasses() ],
94 $meta->superclasses($new_base)
95 if $new_base ne $meta->name();
99 my $existing_class = shift;
101 my $superclasses = shift || [$existing_class];
103 return $existing_class unless $roles;
105 my $meta = Class::MOP::Class->initialize($existing_class);
107 return $existing_class
108 if $meta->can('does_role') && all { $meta->does_role($_) }
109 grep { !ref $_ } @{$roles};
111 return Moose::Meta::Class->create_anon_class(
112 superclasses => $superclasses,
124 Moose::Util::MetaRole - Apply roles to any metaclass, as well as the object base class
128 package MyApp::Moose;
132 use Moose::Util::MetaRole;
134 use MyApp::Role::Meta::Class;
135 use MyApp::Role::Meta::Method::Constructor;
136 use MyApp::Role::Object;
138 Moose::Exporter->setup_import_methods( also => 'Moose' );
144 Moose->init_meta(%options);
146 Moose::Util::MetaRole::apply_metaclass_roles(
147 for_class => $options{for_class},
148 metaclass_roles => ['MyApp::Role::Meta::Class'],
149 constructor_class_roles => ['MyApp::Role::Meta::Method::Constructor'],
152 Moose::Util::MetaRole::apply_base_class_roles(
153 for_class => $options{for_class},
154 roles => ['MyApp::Role::Object'],
157 return $options{for_class}->meta();
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 =item * application_to_class_class_roles => \@roles
215 =item * application_to_role_class_roles => \@roles
217 =item * application_to_instance_class_roles => \@roles
219 These parameter all specify one or more roles to be applied to the
220 specified metaclass. You can pass any or all of these parameters at
225 =head2 apply_base_class_roles( for_class => $class, roles => \@roles )
227 This function will apply the specified roles to the object's base class.
231 Dave Rolsky E<lt>autarch@urth.orgE<gt>
233 =head1 COPYRIGHT AND LICENSE
235 Copyright 2009 by Infinity Interactive, Inc.
237 L<http://www.iinteractive.com>
239 This library is free software; you can redistribute it and/or modify
240 it under the same terms as Perl itself.