2 package Moose::Meta::Role;
8 use Scalar::Util 'blessed';
10 use Devel::GlobalDestruction 'in_global_destruction';
12 our $VERSION = '0.93';
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" );
201 return $self->SUPER::add_attribute(@_);
204 sub _attach_attribute {
205 my ( $self, $attribute ) = @_;
207 $attribute->attach_to_role($self);
210 sub add_required_methods {
215 if (!blessed($method)) {
216 $method = $self->required_method_metaclass->new(
220 $self->get_required_methods_map->{$method->name} = $method;
224 sub add_conflicting_method {
228 if (@_ == 1 && blessed($_[0])) {
232 $method = $self->conflicting_method_metaclass->new(@_);
235 $self->add_required_methods($method);
238 ## ------------------------------------------------------------------
242 # the before/around/after method modifiers are
243 # stored by name, but there can be many methods
244 # then associated with that name. So again we have
245 # lots of similar functionality, so we can do some
246 # meta-programmin' and save some time.
249 foreach my $modifier_type (qw[ before around after ]) {
251 my $attr_reader = "get_${modifier_type}_method_modifiers_map";
253 # create the attribute ...
254 $META->add_attribute("${modifier_type}_method_modifiers" => (
255 reader => $attr_reader,
256 default => sub { {} }
259 # and some helper methods ...
260 $META->add_method("get_${modifier_type}_method_modifiers" => sub {
261 my ($self, $method_name) = @_;
262 #return () unless exists $self->$attr_reader->{$method_name};
263 my $mm = $self->$attr_reader->{$method_name};
267 $META->add_method("has_${modifier_type}_method_modifiers" => sub {
268 my ($self, $method_name) = @_;
270 # for now we assume that if it exists,..
271 # it has at least one modifier in it
272 (exists $self->$attr_reader->{$method_name}) ? 1 : 0;
275 $META->add_method("add_${modifier_type}_method_modifier" => sub {
276 my ($self, $method_name, $method) = @_;
278 $self->$attr_reader->{$method_name} = []
279 unless exists $self->$attr_reader->{$method_name};
281 my $modifiers = $self->$attr_reader->{$method_name};
284 # check to see that we aren't adding the
285 # same code twice. We err in favor of the
286 # first on here, this may not be as expected
287 foreach my $modifier (@{$modifiers}) {
288 return if $modifier == $method;
291 push @{$modifiers} => $method;
296 ## ------------------------------------------------------------------
297 ## override method mofidiers
299 $META->add_attribute('override_method_modifiers' => (
300 reader => 'get_override_method_modifiers_map',
301 default => sub { {} }
305 # these are a little different because there
306 # can only be one per name, whereas the other
307 # method modifiers can have multiples.
310 sub add_override_method_modifier {
311 my ($self, $method_name, $method) = @_;
312 (!$self->has_method($method_name))
313 || Moose->throw_error("Cannot add an override of method '$method_name' " .
314 "because there is a local version of '$method_name'");
315 $self->get_override_method_modifiers_map->{$method_name} = $method;
318 sub has_override_method_modifier {
319 my ($self, $method_name) = @_;
321 # for now we assume that if it exists,..
322 # it has at least one modifier in it
323 (exists $self->get_override_method_modifiers_map->{$method_name}) ? 1 : 0;
326 sub get_override_method_modifier {
327 my ($self, $method_name) = @_;
328 $self->get_override_method_modifiers_map->{$method_name};
331 ## general list accessor ...
333 sub get_method_modifier_list {
334 my ($self, $modifier_type) = @_;
335 my $accessor = "get_${modifier_type}_method_modifiers_map";
336 keys %{$self->$accessor};
339 sub reset_package_cache_flag { (shift)->{'_package_cache_flag'} = undef }
340 sub update_package_cache_flag {
342 $self->{'_package_cache_flag'} = Class::MOP::check_package_cache_flag($self->name);
347 ## ------------------------------------------------------------------
350 $META->add_attribute('roles' => (
351 reader => 'get_roles',
352 default => sub { [] }
356 my ($self, $role) = @_;
357 (blessed($role) && $role->isa('Moose::Meta::Role'))
358 || Moose->throw_error("Roles must be instances of Moose::Meta::Role");
359 push @{$self->get_roles} => $role;
360 $self->reset_package_cache_flag;
363 sub calculate_all_roles {
369 $_->calculate_all_roles
370 } @{ $self->get_roles });
374 my ($self, $role_name) = @_;
376 || Moose->throw_error("You must supply a role name to look for");
377 # if we are it,.. then return true
378 return 1 if $role_name eq $self->name;
379 # otherwise.. check our children
380 foreach my $role (@{$self->get_roles}) {
381 return 1 if $role->does_role($role_name);
386 sub find_method_by_name { (shift)->get_method(@_) }
389 Carp::cluck("The alias_method method is deprecated. Use add_method instead.\n");
393 $self->add_method(@_);
396 ## ------------------------------------------------------------------
398 ## ------------------------------------------------------------------
401 my ($self, $other, @args) = @_;
404 || Moose->throw_error("You must pass in an blessed instance");
406 my $application_class;
407 if ($other->isa('Moose::Meta::Role')) {
408 $application_class = $self->application_to_role_class;
410 elsif ($other->isa('Moose::Meta::Class')) {
411 $application_class = $self->application_to_class_class;
414 $application_class = $self->application_to_instance_class;
417 Class::MOP::load_class($application_class);
418 return $application_class->new(@args)->apply($self, $other);
421 sub composition_class_roles { }
424 my ($class, @role_specs) = @_;
426 require Moose::Meta::Role::Composite;
428 my (@roles, %role_params);
429 while (@role_specs) {
430 my ($role_name, $params) = @{ splice @role_specs, 0, 1 };
431 my $requested_role = Class::MOP::class_of($role_name);
433 my $actual_role = $requested_role->_role_for_combination($params);
434 push @roles => $actual_role;
436 next unless defined $params;
437 $role_params{$actual_role->name} = $params;
440 my $c = Moose::Meta::Role::Composite->new(roles => \@roles);
441 return $c->apply_params(\%role_params);
444 sub _role_for_combination {
445 my ($self, $params) = @_;
450 my ( $role, $package_name, %options ) = @_;
452 $options{package} = $package_name;
454 (ref $options{attributes} eq 'HASH')
455 || confess "You must pass a HASH ref of attributes"
456 if exists $options{attributes};
458 (ref $options{methods} eq 'HASH')
459 || confess "You must pass a HASH ref of methods"
460 if exists $options{methods};
462 my (%initialize_options) = %options;
463 delete @initialize_options{qw(
471 my $meta = $role->initialize( $package_name => %initialize_options );
473 $meta->_instantiate_module( $options{version}, $options{authority} );
476 $meta->add_method('meta' => sub {
477 $role->initialize(ref($_[0]) || $_[0]);
480 if (exists $options{attributes}) {
481 foreach my $attribute_name (keys %{$options{attributes}}) {
482 my $attr = $options{attributes}->{$attribute_name};
483 $meta->add_attribute(
484 $attribute_name => blessed $attr ? $attr : %{$attr} );
488 if (exists $options{methods}) {
489 foreach my $method_name (keys %{$options{methods}}) {
490 $meta->add_method($method_name, $options{methods}->{$method_name});
494 Class::MOP::weaken_metaclass($meta->name)
495 if $meta->is_anon_role;
500 # anonymous roles. most of it is copied straight out of Class::MOP::Class.
501 # an intrepid hacker might find great riches if he unifies this code with that
502 # code in Class::MOP::Module or Class::MOP::Package
505 # this should be sufficient, if you have a
506 # use case where it is not, write a test and
508 my $ANON_ROLE_SERIAL = 0;
511 # we need a sufficiently annoying prefix
512 # this should suffice for now, this is
513 # used in a couple of places below, so
514 # need to put it up here for now.
515 my $ANON_ROLE_PREFIX = 'Moose::Meta::Role::__ANON__::SERIAL::';
519 no warnings 'uninitialized';
520 $self->name =~ /^$ANON_ROLE_PREFIX/;
523 sub create_anon_role {
524 my ($role, %options) = @_;
525 my $package_name = $ANON_ROLE_PREFIX . ++$ANON_ROLE_SERIAL;
526 return $role->create($package_name, %options);
530 # this will only get called for
531 # anon-roles, all other calls
532 # are assumed to occur during
533 # global destruction and so don't
534 # really need to be handled explicitly
538 return if in_global_destruction(); # it'll happen soon anyway and this just makes things more complicated
540 no warnings 'uninitialized';
541 return unless $self->name =~ /^$ANON_ROLE_PREFIX/;
543 # XXX: is this necessary for us? I don't understand what it's doing
546 # Moose does a weird thing where it replaces the metaclass for
547 # class when fixing metaclass incompatibility. In that case,
548 # we don't want to clean out the namespace now. We can detect
549 # that because Moose will explicitly update the singleton
550 # cache in Class::MOP.
551 #my $current_meta = Class::MOP::get_metaclass_by_name($self->name);
552 #return if $current_meta ne $self;
554 my ($serial_id) = ($self->name =~ /^$ANON_ROLE_PREFIX(\d+)/);
556 foreach my $key (keys %{$ANON_ROLE_PREFIX . $serial_id}) {
557 delete ${$ANON_ROLE_PREFIX . $serial_id}{$key};
559 delete ${'main::' . $ANON_ROLE_PREFIX}{$serial_id . '::'};
563 #####################################################################
565 ## This is Moose::Meta::Role as defined by Moose (plus the use of
566 ## MooseX::AttributeHelpers module). It is here as a reference to
567 ## make it easier to see what is happening above with all the meta
569 #####################################################################
572 # metaclass => 'Array',
573 # reader => 'get_roles',
574 # isa => 'ArrayRef[Moose::Meta::Role]',
575 # default => sub { [] },
577 # 'push' => 'add_role',
581 # has 'excluded_roles_map' => (
582 # metaclass => 'Hash',
583 # reader => 'get_excluded_roles_map',
584 # isa => 'HashRef[Str]',
586 # # Not exactly set, cause it sets multiple
587 # 'set' => 'add_excluded_roles',
588 # 'keys' => 'get_excluded_roles_list',
589 # 'exists' => 'excludes_role',
593 # has 'required_methods' => (
594 # metaclass => 'Hash',
595 # reader => 'get_required_methods_map',
596 # isa => 'HashRef[Moose::Meta::Role::Method::Required]',
598 # # not exactly set, or delete since it works for multiple
599 # 'set' => 'add_required_methods',
600 # 'delete' => 'remove_required_methods',
601 # 'keys' => 'get_required_method_list',
602 # 'exists' => 'requires_method',
606 # # the before, around and after modifiers are
607 # # HASH keyed by method-name, with ARRAY of
608 # # CODE refs to apply in that order
610 # has 'before_method_modifiers' => (
611 # metaclass => 'Hash',
612 # reader => 'get_before_method_modifiers_map',
613 # isa => 'HashRef[ArrayRef[CodeRef]]',
615 # 'keys' => 'get_before_method_modifiers',
616 # 'exists' => 'has_before_method_modifiers',
617 # # This actually makes sure there is an
618 # # ARRAY at the given key, and pushed onto
619 # # it. It also checks for duplicates as well
620 # # 'add' => 'add_before_method_modifier'
624 # has 'after_method_modifiers' => (
625 # metaclass => 'Hash',
626 # reader =>'get_after_method_modifiers_map',
627 # isa => 'HashRef[ArrayRef[CodeRef]]',
629 # 'keys' => 'get_after_method_modifiers',
630 # 'exists' => 'has_after_method_modifiers',
631 # # This actually makes sure there is an
632 # # ARRAY at the given key, and pushed onto
633 # # it. It also checks for duplicates as well
634 # # 'add' => 'add_after_method_modifier'
638 # has 'around_method_modifiers' => (
639 # metaclass => 'Hash',
640 # reader =>'get_around_method_modifiers_map',
641 # isa => 'HashRef[ArrayRef[CodeRef]]',
643 # 'keys' => 'get_around_method_modifiers',
644 # 'exists' => 'has_around_method_modifiers',
645 # # This actually makes sure there is an
646 # # ARRAY at the given key, and pushed onto
647 # # it. It also checks for duplicates as well
648 # # 'add' => 'add_around_method_modifier'
652 # # override is similar to the other modifiers
653 # # except that it is not an ARRAY of code refs
654 # # but instead just a single name->code mapping
656 # has 'override_method_modifiers' => (
657 # metaclass => 'Hash',
658 # reader =>'get_override_method_modifiers_map',
659 # isa => 'HashRef[CodeRef]',
661 # 'keys' => 'get_override_method_modifier',
662 # 'exists' => 'has_override_method_modifier',
663 # 'add' => 'add_override_method_modifier', # checks for local method ..
667 #####################################################################
678 Moose::Meta::Role - The Moose Role metaclass
682 This class is a subclass of L<Class::MOP::Module> that provides
683 additional Moose-specific functionality.
685 It's API looks a lot like L<Moose::Meta::Class>, but internally it
686 implements many things differently. This may change in the future.
690 C<Moose::Meta::Role> is a subclass of L<Class::MOP::Module>.
698 =item B<< Moose::Meta::Role->initialize($role_name) >>
700 This method creates a new role object with the provided name.
702 =item B<< Moose::Meta::Role->combine( [ $role => { ... } ], [ $role ], ... ) >>
704 This method accepts a list of array references. Each array reference
705 should contain a role name as its first element. The second element is
706 an optional hash reference. The hash reference can contain C<-excludes>
707 and C<-alias> keys to control how methods are composed from the role.
709 The return value is a new L<Moose::Meta::Role::Composite> that
710 represents the combined roles.
712 =item B<< $metarole->composition_class_roles >>
714 When combining multiple roles using C<combine>, this method is used to obtain a
715 list of role names to be applied to the L<Moose::Meta::Role::Composite>
716 instance returned by C<combine>. The default implementation returns an empty
717 list. Extensions that need to hook into role combination may wrap this method
718 to return additional role names.
720 =item B<< Moose::Meta::Role->create($name, %options) >>
722 This method is identical to the L<Moose::Meta::Class> C<create>
725 =item B<< Moose::Meta::Role->create_anon_role >>
727 This method is identical to the L<Moose::Meta::Class>
728 C<create_anon_class> method.
730 =item B<< $metarole->is_anon_role >>
732 Returns true if the role is an anonymous role.
736 =head2 Role application
740 =item B<< $metarole->apply( $thing, @options ) >>
742 This method applies a role to the given C<$thing>. That can be another
743 L<Moose::Meta::Role>, object, a L<Moose::Meta::Class> object, or a
744 (non-meta) object instance.
746 The options are passed directly to the constructor for the appropriate
747 L<Moose::Meta::Role::Application> subclass.
749 Note that this will apply the role even if the C<$thing> in question already
750 C<does> this role. L<Moose::Util/does_role> is a convenient wrapper for
751 finding out if role application is necessary.
755 =head2 Roles and other roles
759 =item B<< $metarole->get_roles >>
761 This returns an array reference of roles which this role does. This
762 list may include duplicates.
764 =item B<< $metarole->calculate_all_roles >>
766 This returns a I<unique> list of all roles that this role does, and
767 all the roles that its roles do.
769 =item B<< $metarole->does_role($role_name) >>
771 Given a role I<name>, returns true if this role does the given
774 =item B<< $metarole->add_role($role) >>
776 Given a L<Moose::Meta::Role> object, this adds the role to the list of
777 roles that the role does.
779 =item B<< $metarole->get_excluded_roles_list >>
781 Returns a list of role names which this role excludes.
783 =item B<< $metarole->excludes_role($role_name) >>
785 Given a role I<name>, returns true if this role excludes the named
788 =item B<< $metarole->add_excluded_roles(@role_names) >>
790 Given one or more role names, adds those roles to the list of excluded
797 The methods for dealing with a role's methods are all identical in API
798 and behavior to the same methods in L<Class::MOP::Class>.
802 =item B<< $metarole->method_metaclass >>
804 Returns the method metaclass name for the role. This defaults to
805 L<Moose::Meta::Role::Method>.
807 =item B<< $metarole->get_method($name) >>
809 =item B<< $metarole->has_method($name) >>
811 =item B<< $metarole->add_method( $name, $body ) >>
813 =item B<< $metarole->get_method_list >>
815 =item B<< $metarole->find_method_by_name($name) >>
817 These methods are all identical to the methods of the same name in
818 L<Class::MOP::Package>
824 As with methods, the methods for dealing with a role's attribute are
825 all identical in API and behavior to the same methods in
826 L<Class::MOP::Class>.
828 However, attributes stored in this class are I<not> stored as
829 objects. Rather, the attribute definition is stored as a hash
830 reference. When a role is composed into a class, this hash reference
831 is passed directly to the metaclass's C<add_attribute> method.
833 This is quite likely to change in the future.
837 =item B<< $metarole->get_attribute($attribute_name) >>
839 =item B<< $metarole->has_attribute($attribute_name) >>
841 =item B<< $metarole->get_attribute_list >>
843 =item B<< $metarole->add_attribute($name, %options) >>
845 =item B<< $metarole->remove_attribute($attribute_name) >>
849 =head2 Required methods
853 =item B<< $metarole->get_required_method_list >>
855 Returns the list of methods required by the role.
857 =item B<< $metarole->requires_method($name) >>
859 Returns true if the role requires the named method.
861 =item B<< $metarole->add_required_methods(@names) >>
863 Adds the named methods to the role's list of required methods.
865 =item B<< $metarole->remove_required_methods(@names) >>
867 Removes the named methods from the role's list of required methods.
869 =item B<< $metarole->add_conflicting_method(%params) >>
871 Instantiate the parameters as a L<Moose::Meta::Role::Method::Conflicting>
872 object, then add it to the required method list.
876 =head2 Method modifiers
878 These methods act like their counterparts in L<Class::Mop::Class> and
879 L<Moose::Meta::Class>.
881 However, method modifiers are simply stored internally, and are not
882 applied until the role itself is applied to a class.
886 =item B<< $metarole->add_after_method_modifier($method_name, $method) >>
888 =item B<< $metarole->add_around_method_modifier($method_name, $method) >>
890 =item B<< $metarole->add_before_method_modifier($method_name, $method) >>
892 =item B<< $metarole->add_override_method_modifier($method_name, $method) >>
894 These methods all add an appropriate modifier to the internal list of
897 =item B<< $metarole->has_after_method_modifiers >>
899 =item B<< $metarole->has_around_method_modifiers >>
901 =item B<< $metarole->has_before_method_modifiers >>
903 =item B<< $metarole->has_override_method_modifier >>
905 Return true if the role has any modifiers of the given type.
907 =item B<< $metarole->get_after_method_modifiers($method_name) >>
909 =item B<< $metarole->get_around_method_modifiers($method_name) >>
911 =item B<< $metarole->get_before_method_modifiers($method_name) >>
913 Given a method name, returns a list of the appropriate modifiers for
916 =item B<< $metarole->get_override_method_modifier($method_name) >>
918 Given a method name, returns the override method modifier for that
919 method, if it has one.
927 =item B<< Moose::Meta::Role->meta >>
929 This will return a L<Class::MOP::Class> instance for this class.
935 All complex software has bugs lurking in it, and this module is no
936 exception. If you find a bug please either email me, or add the bug
941 Stevan Little E<lt>stevan@iinteractive.comE<gt>
943 =head1 COPYRIGHT AND LICENSE
945 Copyright 2006-2009 by Infinity Interactive, Inc.
947 L<http://www.iinteractive.com>
949 This library is free software; you can redistribute it and/or modify
950 it under the same terms as Perl itself.