2 package Moose::Meta::Role;
8 use Scalar::Util 'blessed';
10 use Devel::GlobalDestruction 'in_global_destruction';
12 our $VERSION = '1.03';
13 $VERSION = eval $VERSION;
14 our $AUTHORITY = 'cpan:STEVAN';
16 use Moose::Meta::Class;
17 use Moose::Meta::Role::Attribute;
18 use Moose::Meta::Role::Method;
19 use Moose::Meta::Role::Method::Required;
20 use Moose::Meta::Role::Method::Conflicting;
21 use Moose::Util qw( ensure_all_roles );
23 use base 'Class::MOP::Module', 'Class::MOP::Mixin::HasAttributes';
25 ## ------------------------------------------------------------------
27 ## I normally don't do this, but I am doing
28 ## a whole bunch of meta-programmin in this
29 ## module, so it just makes sense. For a clearer
30 ## picture of what is going on in the next
31 ## several lines of code, look at the really
32 ## big comment at the end of this file (right
35 ## ------------------------------------------------------------------
37 my $META = __PACKAGE__->meta;
39 ## ------------------------------------------------------------------
43 # since roles are lazy, we hold all the attributes
44 # of the individual role in 'statis' until which
45 # time when it is applied to a class. This means
46 # keeping a lot of things in hash maps, so we are
47 # using a little of that meta-programmin' magic
48 # here an saving lots of extra typin. And since
49 # many of these attributes above require similar
50 # functionality to support them, so we again use
51 # the wonders of meta-programmin' to deliver a
52 # very compact solution to this normally verbose
58 name => 'excluded_roles_map',
59 attr_reader => 'get_excluded_roles_map' ,
61 add => 'add_excluded_roles',
62 get_keys => 'get_excluded_roles_list',
63 existence => 'excludes_role',
67 name => 'required_methods',
68 attr_reader => 'get_required_methods_map',
70 remove => 'remove_required_methods',
71 get_values => 'get_required_method_list',
72 existence => 'requires_method',
77 my $attr_reader = $action->{attr_reader};
78 my $methods = $action->{methods};
80 # create the attribute
81 $META->add_attribute($action->{name} => (
82 reader => $attr_reader,
86 # create some helper methods
87 $META->add_method($methods->{add} => sub {
88 my ($self, @values) = @_;
89 $self->$attr_reader->{$_} = undef foreach @values;
90 }) if exists $methods->{add};
92 $META->add_method($methods->{get_keys} => sub {
94 keys %{$self->$attr_reader};
95 }) if exists $methods->{get_keys};
97 $META->add_method($methods->{get_values} => sub {
99 values %{$self->$attr_reader};
100 }) if exists $methods->{get_values};
102 $META->add_method($methods->{get} => sub {
103 my ($self, $name) = @_;
104 $self->$attr_reader->{$name}
105 }) if exists $methods->{get};
107 $META->add_method($methods->{existence} => sub {
108 my ($self, $name) = @_;
109 exists $self->$attr_reader->{$name} ? 1 : 0;
110 }) if exists $methods->{existence};
112 $META->add_method($methods->{remove} => sub {
113 my ($self, @values) = @_;
114 delete $self->$attr_reader->{$_} foreach @values;
115 }) if exists $methods->{remove};
118 $META->add_attribute(
120 reader => 'method_metaclass',
121 default => 'Moose::Meta::Role::Method',
124 $META->add_attribute(
125 'required_method_metaclass',
126 reader => 'required_method_metaclass',
127 default => 'Moose::Meta::Role::Method::Required',
130 $META->add_attribute(
131 'conflicting_method_metaclass',
132 reader => 'conflicting_method_metaclass',
133 default => 'Moose::Meta::Role::Method::Conflicting',
136 $META->add_attribute(
137 'application_to_class_class',
138 reader => 'application_to_class_class',
139 default => 'Moose::Meta::Role::Application::ToClass',
142 $META->add_attribute(
143 'application_to_role_class',
144 reader => 'application_to_role_class',
145 default => 'Moose::Meta::Role::Application::ToRole',
148 $META->add_attribute(
149 'application_to_instance_class',
150 reader => 'application_to_instance_class',
151 default => 'Moose::Meta::Role::Application::ToInstance',
154 # More or less copied from Moose::Meta::Class
158 return Class::MOP::get_metaclass_by_name($pkg)
159 || $class->SUPER::initialize(
161 'attribute_metaclass' => 'Moose::Meta::Role::Attribute',
170 my $meta = blessed $pkg ? $pkg : Class::MOP::class_of($pkg);
172 my %existing_classes;
174 %existing_classes = map { $_ => $meta->$_() } qw(
177 wrapped_method_metaclass
178 required_method_metaclass
179 conflicting_method_metaclass
180 application_to_class_class
181 application_to_role_class
182 application_to_instance_class
186 return $self->SUPER::reinitialize(
196 if (blessed $_[0] && ! $_[0]->isa('Moose::Meta::Role::Attribute') ) {
197 my $class = ref $_[0];
198 Moose->throw_error( "Cannot add a $class as an attribute to a role" );
200 elsif (!blessed($_[0]) && $_[0] =~ /^\+(.*)/) {
201 Moose->throw_error( "has '+attr' is not supported in roles" );
204 return $self->SUPER::add_attribute(@_);
207 sub _attach_attribute {
208 my ( $self, $attribute ) = @_;
210 $attribute->attach_to_role($self);
213 sub add_required_methods {
218 if (!blessed($method)) {
219 $method = $self->required_method_metaclass->new(
223 $self->get_required_methods_map->{$method->name} = $method;
227 sub add_conflicting_method {
231 if (@_ == 1 && blessed($_[0])) {
235 $method = $self->conflicting_method_metaclass->new(@_);
238 $self->add_required_methods($method);
241 ## ------------------------------------------------------------------
245 # the before/around/after method modifiers are
246 # stored by name, but there can be many methods
247 # then associated with that name. So again we have
248 # lots of similar functionality, so we can do some
249 # meta-programmin' and save some time.
252 foreach my $modifier_type (qw[ before around after ]) {
254 my $attr_reader = "get_${modifier_type}_method_modifiers_map";
256 # create the attribute ...
257 $META->add_attribute("${modifier_type}_method_modifiers" => (
258 reader => $attr_reader,
259 default => sub { {} }
262 # and some helper methods ...
263 $META->add_method("get_${modifier_type}_method_modifiers" => sub {
264 my ($self, $method_name) = @_;
265 #return () unless exists $self->$attr_reader->{$method_name};
266 my $mm = $self->$attr_reader->{$method_name};
270 $META->add_method("has_${modifier_type}_method_modifiers" => sub {
271 my ($self, $method_name) = @_;
273 # for now we assume that if it exists,..
274 # it has at least one modifier in it
275 (exists $self->$attr_reader->{$method_name}) ? 1 : 0;
278 $META->add_method("add_${modifier_type}_method_modifier" => sub {
279 my ($self, $method_name, $method) = @_;
281 $self->$attr_reader->{$method_name} = []
282 unless exists $self->$attr_reader->{$method_name};
284 my $modifiers = $self->$attr_reader->{$method_name};
287 # check to see that we aren't adding the
288 # same code twice. We err in favor of the
289 # first on here, this may not be as expected
290 foreach my $modifier (@{$modifiers}) {
291 return if $modifier == $method;
294 push @{$modifiers} => $method;
299 ## ------------------------------------------------------------------
300 ## override method mofidiers
302 $META->add_attribute('override_method_modifiers' => (
303 reader => 'get_override_method_modifiers_map',
304 default => sub { {} }
308 # these are a little different because there
309 # can only be one per name, whereas the other
310 # method modifiers can have multiples.
313 sub add_override_method_modifier {
314 my ($self, $method_name, $method) = @_;
315 (!$self->has_method($method_name))
316 || Moose->throw_error("Cannot add an override of method '$method_name' " .
317 "because there is a local version of '$method_name'");
318 $self->get_override_method_modifiers_map->{$method_name} = $method;
321 sub has_override_method_modifier {
322 my ($self, $method_name) = @_;
324 # for now we assume that if it exists,..
325 # it has at least one modifier in it
326 (exists $self->get_override_method_modifiers_map->{$method_name}) ? 1 : 0;
329 sub get_override_method_modifier {
330 my ($self, $method_name) = @_;
331 $self->get_override_method_modifiers_map->{$method_name};
334 ## general list accessor ...
336 sub get_method_modifier_list {
337 my ($self, $modifier_type) = @_;
338 my $accessor = "get_${modifier_type}_method_modifiers_map";
339 keys %{$self->$accessor};
342 sub reset_package_cache_flag { (shift)->{'_package_cache_flag'} = undef }
343 sub update_package_cache_flag {
345 $self->{'_package_cache_flag'} = Class::MOP::check_package_cache_flag($self->name);
350 ## ------------------------------------------------------------------
353 $META->add_attribute('roles' => (
354 reader => 'get_roles',
355 default => sub { [] }
359 my ($self, $role) = @_;
360 (blessed($role) && $role->isa('Moose::Meta::Role'))
361 || Moose->throw_error("Roles must be instances of Moose::Meta::Role");
362 push @{$self->get_roles} => $role;
363 $self->reset_package_cache_flag;
366 sub calculate_all_roles {
372 $_->calculate_all_roles
373 } @{ $self->get_roles });
377 my ($self, $role) = @_;
379 || Moose->throw_error("You must supply a role name to look for");
380 my $role_name = blessed $role ? $role->name : $role;
381 # if we are it,.. then return true
382 return 1 if $role_name eq $self->name;
383 # otherwise.. check our children
384 foreach my $role (@{$self->get_roles}) {
385 return 1 if $role->does_role($role_name);
390 sub find_method_by_name { (shift)->get_method(@_) }
393 Carp::cluck("The alias_method method is deprecated. Use add_method instead.\n");
397 $self->add_method(@_);
400 ## ------------------------------------------------------------------
402 ## ------------------------------------------------------------------
405 my ($self, $other, %args) = @_;
408 || Moose->throw_error("You must pass in an blessed instance");
410 my $application_class;
411 if ($other->isa('Moose::Meta::Role')) {
412 $application_class = $self->application_to_role_class;
414 elsif ($other->isa('Moose::Meta::Class')) {
415 $application_class = $self->application_to_class_class;
418 $application_class = $self->application_to_instance_class;
421 Class::MOP::load_class($application_class);
422 return $application_class->new(%args)->apply($self, $other, \%args);
425 sub composition_class_roles { }
428 my ($class, @role_specs) = @_;
430 require Moose::Meta::Role::Composite;
432 my (@roles, %role_params);
433 while (@role_specs) {
434 my ($role, $params) = @{ splice @role_specs, 0, 1 };
438 : Class::MOP::class_of($role);
440 my $actual_role = $requested_role->_role_for_combination($params);
441 push @roles => $actual_role;
443 next unless defined $params;
444 $role_params{$actual_role->name} = $params;
447 my $c = Moose::Meta::Role::Composite->new(roles => \@roles);
448 return $c->apply_params(\%role_params);
451 sub _role_for_combination {
452 my ($self, $params) = @_;
457 my ( $role, $package_name, %options ) = @_;
459 $options{package} = $package_name;
461 (ref $options{attributes} eq 'HASH')
462 || confess "You must pass a HASH ref of attributes"
463 if exists $options{attributes};
465 (ref $options{methods} eq 'HASH')
466 || confess "You must pass a HASH ref of methods"
467 if exists $options{methods};
469 my (%initialize_options) = %options;
470 delete @initialize_options{qw(
478 my $meta = $role->initialize( $package_name => %initialize_options );
480 $meta->_instantiate_module( $options{version}, $options{authority} );
483 $meta->add_method('meta' => sub {
484 $role->initialize(ref($_[0]) || $_[0]);
487 if (exists $options{attributes}) {
488 foreach my $attribute_name (keys %{$options{attributes}}) {
489 my $attr = $options{attributes}->{$attribute_name};
490 $meta->add_attribute(
491 $attribute_name => blessed $attr ? $attr : %{$attr} );
495 if (exists $options{methods}) {
496 foreach my $method_name (keys %{$options{methods}}) {
497 $meta->add_method($method_name, $options{methods}->{$method_name});
501 Class::MOP::weaken_metaclass($meta->name)
502 if $meta->is_anon_role;
507 # anonymous roles. most of it is copied straight out of Class::MOP::Class.
508 # an intrepid hacker might find great riches if he unifies this code with that
509 # code in Class::MOP::Module or Class::MOP::Package
512 # this should be sufficient, if you have a
513 # use case where it is not, write a test and
515 my $ANON_ROLE_SERIAL = 0;
518 # we need a sufficiently annoying prefix
519 # this should suffice for now, this is
520 # used in a couple of places below, so
521 # need to put it up here for now.
522 my $ANON_ROLE_PREFIX = 'Moose::Meta::Role::__ANON__::SERIAL::';
526 no warnings 'uninitialized';
527 $self->name =~ /^$ANON_ROLE_PREFIX/;
530 sub create_anon_role {
531 my ($role, %options) = @_;
532 my $package_name = $ANON_ROLE_PREFIX . ++$ANON_ROLE_SERIAL;
533 return $role->create($package_name, %options);
537 # this will only get called for
538 # anon-roles, all other calls
539 # are assumed to occur during
540 # global destruction and so don't
541 # really need to be handled explicitly
545 return if in_global_destruction(); # it'll happen soon anyway and this just makes things more complicated
547 no warnings 'uninitialized';
548 return unless $self->name =~ /^$ANON_ROLE_PREFIX/;
550 # XXX: is this necessary for us? I don't understand what it's doing
553 # Moose does a weird thing where it replaces the metaclass for
554 # class when fixing metaclass incompatibility. In that case,
555 # we don't want to clean out the namespace now. We can detect
556 # that because Moose will explicitly update the singleton
557 # cache in Class::MOP.
558 #my $current_meta = Class::MOP::get_metaclass_by_name($self->name);
559 #return if $current_meta ne $self;
561 my ($serial_id) = ($self->name =~ /^$ANON_ROLE_PREFIX(\d+)/);
563 foreach my $key (keys %{$ANON_ROLE_PREFIX . $serial_id}) {
564 delete ${$ANON_ROLE_PREFIX . $serial_id}{$key};
566 delete ${'main::' . $ANON_ROLE_PREFIX}{$serial_id . '::'};
570 #####################################################################
572 ## This is Moose::Meta::Role as defined by Moose (plus the use of
573 ## MooseX::AttributeHelpers module). It is here as a reference to
574 ## make it easier to see what is happening above with all the meta
576 #####################################################################
579 # metaclass => 'Array',
580 # reader => 'get_roles',
581 # isa => 'ArrayRef[Moose::Meta::Role]',
582 # default => sub { [] },
584 # 'push' => 'add_role',
588 # has 'excluded_roles_map' => (
589 # metaclass => 'Hash',
590 # reader => 'get_excluded_roles_map',
591 # isa => 'HashRef[Str]',
593 # # Not exactly set, cause it sets multiple
594 # 'set' => 'add_excluded_roles',
595 # 'keys' => 'get_excluded_roles_list',
596 # 'exists' => 'excludes_role',
600 # has 'required_methods' => (
601 # metaclass => 'Hash',
602 # reader => 'get_required_methods_map',
603 # isa => 'HashRef[Moose::Meta::Role::Method::Required]',
605 # # not exactly set, or delete since it works for multiple
606 # 'set' => 'add_required_methods',
607 # 'delete' => 'remove_required_methods',
608 # 'keys' => 'get_required_method_list',
609 # 'exists' => 'requires_method',
613 # # the before, around and after modifiers are
614 # # HASH keyed by method-name, with ARRAY of
615 # # CODE refs to apply in that order
617 # has 'before_method_modifiers' => (
618 # metaclass => 'Hash',
619 # reader => 'get_before_method_modifiers_map',
620 # isa => 'HashRef[ArrayRef[CodeRef]]',
622 # 'keys' => 'get_before_method_modifiers',
623 # 'exists' => 'has_before_method_modifiers',
624 # # This actually makes sure there is an
625 # # ARRAY at the given key, and pushed onto
626 # # it. It also checks for duplicates as well
627 # # 'add' => 'add_before_method_modifier'
631 # has 'after_method_modifiers' => (
632 # metaclass => 'Hash',
633 # reader =>'get_after_method_modifiers_map',
634 # isa => 'HashRef[ArrayRef[CodeRef]]',
636 # 'keys' => 'get_after_method_modifiers',
637 # 'exists' => 'has_after_method_modifiers',
638 # # This actually makes sure there is an
639 # # ARRAY at the given key, and pushed onto
640 # # it. It also checks for duplicates as well
641 # # 'add' => 'add_after_method_modifier'
645 # has 'around_method_modifiers' => (
646 # metaclass => 'Hash',
647 # reader =>'get_around_method_modifiers_map',
648 # isa => 'HashRef[ArrayRef[CodeRef]]',
650 # 'keys' => 'get_around_method_modifiers',
651 # 'exists' => 'has_around_method_modifiers',
652 # # This actually makes sure there is an
653 # # ARRAY at the given key, and pushed onto
654 # # it. It also checks for duplicates as well
655 # # 'add' => 'add_around_method_modifier'
659 # # override is similar to the other modifiers
660 # # except that it is not an ARRAY of code refs
661 # # but instead just a single name->code mapping
663 # has 'override_method_modifiers' => (
664 # metaclass => 'Hash',
665 # reader =>'get_override_method_modifiers_map',
666 # isa => 'HashRef[CodeRef]',
668 # 'keys' => 'get_override_method_modifier',
669 # 'exists' => 'has_override_method_modifier',
670 # 'add' => 'add_override_method_modifier', # checks for local method ..
674 #####################################################################
685 Moose::Meta::Role - The Moose Role metaclass
689 This class is a subclass of L<Class::MOP::Module> that provides
690 additional Moose-specific functionality.
692 It's API looks a lot like L<Moose::Meta::Class>, but internally it
693 implements many things differently. This may change in the future.
697 C<Moose::Meta::Role> is a subclass of L<Class::MOP::Module>.
705 =item B<< Moose::Meta::Role->initialize($role_name) >>
707 This method creates a new role object with the provided name.
709 =item B<< Moose::Meta::Role->combine( [ $role => { ... } ], [ $role ], ... ) >>
711 This method accepts a list of array references. Each array reference
712 should contain a role name or L<Moose::Meta::Role> object as its first element. The second element is
713 an optional hash reference. The hash reference can contain C<-excludes>
714 and C<-alias> keys to control how methods are composed from the role.
716 The return value is a new L<Moose::Meta::Role::Composite> that
717 represents the combined roles.
719 =item B<< $metarole->composition_class_roles >>
721 When combining multiple roles using C<combine>, this method is used to obtain a
722 list of role names to be applied to the L<Moose::Meta::Role::Composite>
723 instance returned by C<combine>. The default implementation returns an empty
724 list. Extensions that need to hook into role combination may wrap this method
725 to return additional role names.
727 =item B<< Moose::Meta::Role->create($name, %options) >>
729 This method is identical to the L<Moose::Meta::Class> C<create>
732 =item B<< Moose::Meta::Role->create_anon_role >>
734 This method is identical to the L<Moose::Meta::Class>
735 C<create_anon_class> method.
737 =item B<< $metarole->is_anon_role >>
739 Returns true if the role is an anonymous role.
743 =head2 Role application
747 =item B<< $metarole->apply( $thing, @options ) >>
749 This method applies a role to the given C<$thing>. That can be another
750 L<Moose::Meta::Role>, object, a L<Moose::Meta::Class> object, or a
751 (non-meta) object instance.
753 The options are passed directly to the constructor for the appropriate
754 L<Moose::Meta::Role::Application> subclass.
756 Note that this will apply the role even if the C<$thing> in question already
757 C<does> this role. L<Moose::Util/does_role> is a convenient wrapper for
758 finding out if role application is necessary.
762 =head2 Roles and other roles
766 =item B<< $metarole->get_roles >>
768 This returns an array reference of roles which this role does. This
769 list may include duplicates.
771 =item B<< $metarole->calculate_all_roles >>
773 This returns a I<unique> list of all roles that this role does, and
774 all the roles that its roles do.
776 =item B<< $metarole->does_role($role) >>
778 Given a role I<name> or L<Moose::Meta::Role> object, returns true if this role
781 =item B<< $metarole->add_role($role) >>
783 Given a L<Moose::Meta::Role> object, this adds the role to the list of
784 roles that the role does.
786 =item B<< $metarole->get_excluded_roles_list >>
788 Returns a list of role names which this role excludes.
790 =item B<< $metarole->excludes_role($role_name) >>
792 Given a role I<name>, returns true if this role excludes the named
795 =item B<< $metarole->add_excluded_roles(@role_names) >>
797 Given one or more role names, adds those roles to the list of excluded
804 The methods for dealing with a role's methods are all identical in API
805 and behavior to the same methods in L<Class::MOP::Class>.
809 =item B<< $metarole->method_metaclass >>
811 Returns the method metaclass name for the role. This defaults to
812 L<Moose::Meta::Role::Method>.
814 =item B<< $metarole->get_method($name) >>
816 =item B<< $metarole->has_method($name) >>
818 =item B<< $metarole->add_method( $name, $body ) >>
820 =item B<< $metarole->get_method_list >>
822 =item B<< $metarole->find_method_by_name($name) >>
824 These methods are all identical to the methods of the same name in
825 L<Class::MOP::Package>
831 As with methods, the methods for dealing with a role's attribute are
832 all identical in API and behavior to the same methods in
833 L<Class::MOP::Class>.
835 However, attributes stored in this class are I<not> stored as
836 objects. Rather, the attribute definition is stored as a hash
837 reference. When a role is composed into a class, this hash reference
838 is passed directly to the metaclass's C<add_attribute> method.
840 This is quite likely to change in the future.
844 =item B<< $metarole->get_attribute($attribute_name) >>
846 =item B<< $metarole->has_attribute($attribute_name) >>
848 =item B<< $metarole->get_attribute_list >>
850 =item B<< $metarole->add_attribute($name, %options) >>
852 =item B<< $metarole->remove_attribute($attribute_name) >>
856 =head2 Required methods
860 =item B<< $metarole->get_required_method_list >>
862 Returns the list of methods required by the role.
864 =item B<< $metarole->requires_method($name) >>
866 Returns true if the role requires the named method.
868 =item B<< $metarole->add_required_methods(@names) >>
870 Adds the named methods to the role's list of required methods.
872 =item B<< $metarole->remove_required_methods(@names) >>
874 Removes the named methods from the role's list of required methods.
876 =item B<< $metarole->add_conflicting_method(%params) >>
878 Instantiate the parameters as a L<Moose::Meta::Role::Method::Conflicting>
879 object, then add it to the required method list.
883 =head2 Method modifiers
885 These methods act like their counterparts in L<Class::MOP::Class> and
886 L<Moose::Meta::Class>.
888 However, method modifiers are simply stored internally, and are not
889 applied until the role itself is applied to a class.
893 =item B<< $metarole->add_after_method_modifier($method_name, $method) >>
895 =item B<< $metarole->add_around_method_modifier($method_name, $method) >>
897 =item B<< $metarole->add_before_method_modifier($method_name, $method) >>
899 =item B<< $metarole->add_override_method_modifier($method_name, $method) >>
901 These methods all add an appropriate modifier to the internal list of
904 =item B<< $metarole->has_after_method_modifiers >>
906 =item B<< $metarole->has_around_method_modifiers >>
908 =item B<< $metarole->has_before_method_modifiers >>
910 =item B<< $metarole->has_override_method_modifier >>
912 Return true if the role has any modifiers of the given type.
914 =item B<< $metarole->get_after_method_modifiers($method_name) >>
916 =item B<< $metarole->get_around_method_modifiers($method_name) >>
918 =item B<< $metarole->get_before_method_modifiers($method_name) >>
920 Given a method name, returns a list of the appropriate modifiers for
923 =item B<< $metarole->get_override_method_modifier($method_name) >>
925 Given a method name, returns the override method modifier for that
926 method, if it has one.
934 =item B<< Moose::Meta::Role->meta >>
936 This will return a L<Class::MOP::Class> instance for this class.
942 See L<Moose/BUGS> for details on reporting bugs.
946 Stevan Little E<lt>stevan@iinteractive.comE<gt>
948 =head1 COPYRIGHT AND LICENSE
950 Copyright 2006-2010 by Infinity Interactive, Inc.
952 L<http://www.iinteractive.com>
954 This library is free software; you can redistribute it and/or modify
955 it under the same terms as Perl itself.