1 package Mouse::Util::MetaRole;
2 use Mouse::Util; # enables strict and warnings
4 my @MetaClassTypes = qw(
12 # In Mouse::Exporter::do_import():
13 # apply_metaclass_roles(for_class => $class, metaclass_roles => \@traits)
14 sub apply_metaclass_roles {
17 my $for = Scalar::Util::blessed($options{for_class})
19 : Mouse::Util::get_metaclass_by_name($options{for_class});
21 my $new_metaclass = _make_new_class( ref $for,
22 $options{metaclass_roles},
23 $options{metaclass} ? [$options{metaclass}] : undef,
28 foreach my $mc_type(@MetaClassTypes){
29 next if !$for->can($mc_type);
31 if(my $roles = $options{ $mc_type . '_roles' }){
33 ($mc_type => _make_new_class($for->$mc_type(), $roles));
35 elsif(my $mc = $options{$mc_type}){
36 push @metaclass_map, ($mc_type => $mc);
40 return $new_metaclass->reinitialize( $for, @metaclass_map );
43 sub apply_base_class_roles {
46 my $for = $options{for_class};
48 my $meta = Mouse::Util::class_of($for);
50 my $new_base = _make_new_class(
53 [ $meta->superclasses() ],
56 $meta->superclasses($new_base)
57 if $new_base ne $meta->name();
62 my($existing_class, $roles, $superclasses) = @_;
65 return $existing_class if !$roles;
67 my $meta = Mouse::Meta::Class->initialize($existing_class);
69 return $existing_class
70 if !grep { !ref($_) && !$meta->does_role($_) } @{$roles};
73 return Mouse::Meta::Class->create_anon_class(
74 superclasses => $superclasses ? $superclasses : [$existing_class],
86 Mouse::Util::MetaRole - Apply roles to any metaclass, as well as the object base class
94 use Mouse::Util::MetaRole;
96 use MyApp::Role::Meta::Class;
97 use MyApp::Role::Meta::Method::Constructor;
98 use MyApp::Role::Object;
100 Mouse::Exporter->setup_import_methods( also => 'Mouse' );
106 Mouse->init_meta(%options);
108 Mouse::Util::MetaRole::apply_metaclass_roles(
109 for_class => $options{for_class},
110 metaclass_roles => ['MyApp::Role::Meta::Class'],
111 constructor_class_roles => ['MyApp::Role::Meta::Method::Constructor'],
114 Mouse::Util::MetaRole::apply_base_class_roles(
115 for_class => $options{for_class},
116 roles => ['MyApp::Role::Object'],
119 return $options{for_class}->meta();
124 This utility module is designed to help authors of Mouse extensions
125 write extensions that are able to cooperate with other Mouse
126 extensions. To do this, you must write your extensions as roles, which
127 can then be dynamically applied to the caller's metaclasses.
129 This module makes sure to preserve any existing superclasses and roles
130 already set for the meta objects, which means that any number of
131 extensions can apply roles in any order.
135 B<It is very important that you only call this module's functions when
136 your module is imported by the caller>. The process of applying roles
137 to the metaclass reinitializes the metaclass object, which wipes out
138 any existing attributes already defined. However, as long as you do
139 this when your module is imported, the caller should not have any
140 attributes defined yet.
142 The easiest way to ensure that this happens is to use
143 L<Mouse::Exporter>, which can generate the appropriate C<init_meta>
144 method for you, and make sure it is called when imported.
148 This module provides two functions.
150 =head2 apply_metaclass_roles( ... )
152 This function will apply roles to one or more metaclasses for the
153 specified class. It accepts the following parameters:
157 =item * for_class => $name
159 This specifies the class for which to alter the meta classes.
161 =item * metaclass_roles => \@roles
163 =item * attribute_metaclass_roles => \@roles
165 =item * method_metaclass_roles => \@roles
167 =item * constructor_class_roles => \@roles
169 =item * destructor_class_roles => \@roles
171 These parameter all specify one or more roles to be applied to the
172 specified metaclass. You can pass any or all of these parameters at
177 =head2 apply_base_class_roles( for_class => $class, roles => \@roles )
179 This function will apply the specified roles to the object's base class.
183 L<Moose::Util::MetaRole>