package Moose::Meta::Role; use strict; use warnings; use metaclass; use Scalar::Util 'blessed'; use Carp 'confess'; use Devel::GlobalDestruction 'in_global_destruction'; our $VERSION = '1.08'; $VERSION = eval $VERSION; our $AUTHORITY = 'cpan:STEVAN'; use Moose::Meta::Class; use Moose::Meta::Role::Attribute; use Moose::Meta::Role::Method; use Moose::Meta::Role::Method::Required; use Moose::Meta::Role::Method::Conflicting; use Moose::Util qw( ensure_all_roles ); use base 'Class::MOP::Module', 'Class::MOP::Mixin::HasAttributes', 'Class::MOP::Mixin::HasMethods'; ## ------------------------------------------------------------------ ## NOTE: ## I normally don't do this, but I am doing ## a whole bunch of meta-programmin in this ## module, so it just makes sense. For a clearer ## picture of what is going on in the next ## several lines of code, look at the really ## big comment at the end of this file (right ## before the POD). ## - SL ## ------------------------------------------------------------------ my $META = __PACKAGE__->meta; ## ------------------------------------------------------------------ ## attributes ... # NOTE: # since roles are lazy, we hold all the attributes # of the individual role in 'statis' until which # time when it is applied to a class. This means # keeping a lot of things in hash maps, so we are # using a little of that meta-programmin' magic # here an saving lots of extra typin. And since # many of these attributes above require similar # functionality to support them, so we again use # the wonders of meta-programmin' to deliver a # very compact solution to this normally verbose # problem. # - SL foreach my $action ( { name => 'excluded_roles_map', attr_reader => 'get_excluded_roles_map' , methods => { add => 'add_excluded_roles', get_keys => 'get_excluded_roles_list', existence => 'excludes_role', } }, { name => 'required_methods', attr_reader => 'get_required_methods_map', methods => { remove => 'remove_required_methods', get_values => 'get_required_method_list', existence => 'requires_method', } }, ) { my $attr_reader = $action->{attr_reader}; my $methods = $action->{methods}; # create the attribute $META->add_attribute($action->{name} => ( reader => $attr_reader, default => sub { {} } )); # create some helper methods $META->add_method($methods->{add} => sub { my ($self, @values) = @_; $self->$attr_reader->{$_} = undef foreach @values; }) if exists $methods->{add}; $META->add_method($methods->{get_keys} => sub { my ($self) = @_; keys %{$self->$attr_reader}; }) if exists $methods->{get_keys}; $META->add_method($methods->{get_values} => sub { my ($self) = @_; values %{$self->$attr_reader}; }) if exists $methods->{get_values}; $META->add_method($methods->{get} => sub { my ($self, $name) = @_; $self->$attr_reader->{$name} }) if exists $methods->{get}; $META->add_method($methods->{existence} => sub { my ($self, $name) = @_; exists $self->$attr_reader->{$name} ? 1 : 0; }) if exists $methods->{existence}; $META->add_method($methods->{remove} => sub { my ($self, @values) = @_; delete $self->$attr_reader->{$_} foreach @values; }) if exists $methods->{remove}; } $META->add_attribute( 'method_metaclass', reader => 'method_metaclass', default => 'Moose::Meta::Role::Method', ); $META->add_attribute( 'required_method_metaclass', reader => 'required_method_metaclass', default => 'Moose::Meta::Role::Method::Required', ); $META->add_attribute( 'conflicting_method_metaclass', reader => 'conflicting_method_metaclass', default => 'Moose::Meta::Role::Method::Conflicting', ); $META->add_attribute( 'application_to_class_class', reader => 'application_to_class_class', default => 'Moose::Meta::Role::Application::ToClass', ); $META->add_attribute( 'application_to_role_class', reader => 'application_to_role_class', default => 'Moose::Meta::Role::Application::ToRole', ); $META->add_attribute( 'application_to_instance_class', reader => 'application_to_instance_class', default => 'Moose::Meta::Role::Application::ToInstance', ); # More or less copied from Moose::Meta::Class sub initialize { my $class = shift; my $pkg = shift; return Class::MOP::get_metaclass_by_name($pkg) || $class->SUPER::initialize( $pkg, 'attribute_metaclass' => 'Moose::Meta::Role::Attribute', @_ ); } sub reinitialize { my $self = shift; my $pkg = shift; my $meta = blessed $pkg ? $pkg : Class::MOP::class_of($pkg); my %existing_classes; if ($meta) { %existing_classes = map { $_ => $meta->$_() } qw( attribute_metaclass method_metaclass wrapped_method_metaclass required_method_metaclass conflicting_method_metaclass application_to_class_class application_to_role_class application_to_instance_class ); } return $self->SUPER::reinitialize( $pkg, %existing_classes, @_, ); } sub add_attribute { my $self = shift; if (blessed $_[0] && ! $_[0]->isa('Moose::Meta::Role::Attribute') ) { my $class = ref $_[0]; Moose->throw_error( "Cannot add a $class as an attribute to a role" ); } elsif (!blessed($_[0]) && defined($_[0]) && $_[0] =~ /^\+(.*)/) { Moose->throw_error( "has '+attr' is not supported in roles" ); } return $self->SUPER::add_attribute(@_); } sub _attach_attribute { my ( $self, $attribute ) = @_; $attribute->attach_to_role($self); } sub add_required_methods { my $self = shift; for (@_) { my $method = $_; if (!blessed($method)) { $method = $self->required_method_metaclass->new( name => $method, ); } $self->get_required_methods_map->{$method->name} = $method; } } sub add_conflicting_method { my $self = shift; my $method; if (@_ == 1 && blessed($_[0])) { $method = shift; } else { $method = $self->conflicting_method_metaclass->new(@_); } $self->add_required_methods($method); } ## ------------------------------------------------------------------ ## method modifiers # NOTE: # the before/around/after method modifiers are # stored by name, but there can be many methods # then associated with that name. So again we have # lots of similar functionality, so we can do some # meta-programmin' and save some time. # - SL foreach my $modifier_type (qw[ before around after ]) { my $attr_reader = "get_${modifier_type}_method_modifiers_map"; # create the attribute ... $META->add_attribute("${modifier_type}_method_modifiers" => ( reader => $attr_reader, default => sub { {} } )); # and some helper methods ... $META->add_method("get_${modifier_type}_method_modifiers" => sub { my ($self, $method_name) = @_; #return () unless exists $self->$attr_reader->{$method_name}; my $mm = $self->$attr_reader->{$method_name}; $mm ? @$mm : (); }); $META->add_method("has_${modifier_type}_method_modifiers" => sub { my ($self, $method_name) = @_; # NOTE: # for now we assume that if it exists,.. # it has at least one modifier in it (exists $self->$attr_reader->{$method_name}) ? 1 : 0; }); $META->add_method("add_${modifier_type}_method_modifier" => sub { my ($self, $method_name, $method) = @_; $self->$attr_reader->{$method_name} = [] unless exists $self->$attr_reader->{$method_name}; my $modifiers = $self->$attr_reader->{$method_name}; # NOTE: # check to see that we aren't adding the # same code twice. We err in favor of the # first on here, this may not be as expected foreach my $modifier (@{$modifiers}) { return if $modifier == $method; } push @{$modifiers} => $method; }); } ## ------------------------------------------------------------------ ## override method mofidiers $META->add_attribute('override_method_modifiers' => ( reader => 'get_override_method_modifiers_map', default => sub { {} } )); # NOTE: # these are a little different because there # can only be one per name, whereas the other # method modifiers can have multiples. # - SL sub add_override_method_modifier { my ($self, $method_name, $method) = @_; (!$self->has_method($method_name)) || Moose->throw_error("Cannot add an override of method '$method_name' " . "because there is a local version of '$method_name'"); $self->get_override_method_modifiers_map->{$method_name} = $method; } sub has_override_method_modifier { my ($self, $method_name) = @_; # NOTE: # for now we assume that if it exists,.. # it has at least one modifier in it (exists $self->get_override_method_modifiers_map->{$method_name}) ? 1 : 0; } sub get_override_method_modifier { my ($self, $method_name) = @_; $self->get_override_method_modifiers_map->{$method_name}; } ## general list accessor ... sub get_method_modifier_list { my ($self, $modifier_type) = @_; my $accessor = "get_${modifier_type}_method_modifiers_map"; keys %{$self->$accessor}; } sub reset_package_cache_flag { (shift)->{'_package_cache_flag'} = undef } sub update_package_cache_flag { my $self = shift; $self->{'_package_cache_flag'} = Class::MOP::check_package_cache_flag($self->name); } ## ------------------------------------------------------------------ ## subroles $META->add_attribute('roles' => ( reader => 'get_roles', default => sub { [] } )); sub add_role { my ($self, $role) = @_; (blessed($role) && $role->isa('Moose::Meta::Role')) || Moose->throw_error("Roles must be instances of Moose::Meta::Role"); push @{$self->get_roles} => $role; $self->reset_package_cache_flag; } sub calculate_all_roles { my $self = shift; my %seen; grep { !$seen{$_->name}++ } ($self, map { $_->calculate_all_roles } @{ $self->get_roles }); } sub does_role { my ($self, $role) = @_; (defined $role) || Moose->throw_error("You must supply a role name to look for"); my $role_name = blessed $role ? $role->name : $role; # if we are it,.. then return true return 1 if $role_name eq $self->name; # otherwise.. check our children foreach my $role (@{$self->get_roles}) { return 1 if $role->does_role($role_name); } return 0; } sub find_method_by_name { (shift)->get_method(@_) } sub alias_method { Carp::cluck("The alias_method method is deprecated. Use add_method instead.\n"); my $self = shift; $self->add_method(@_); } ## ------------------------------------------------------------------ ## role construction ## ------------------------------------------------------------------ sub apply { my ($self, $other, %args) = @_; (blessed($other)) || Moose->throw_error("You must pass in an blessed instance"); my $application_class; if ($other->isa('Moose::Meta::Role')) { $application_class = $self->application_to_role_class; } elsif ($other->isa('Moose::Meta::Class')) { $application_class = $self->application_to_class_class; } else { $application_class = $self->application_to_instance_class; } Class::MOP::load_class($application_class); return $application_class->new(%args)->apply($self, $other, \%args); } sub composition_class_roles { } sub combine { my ($class, @role_specs) = @_; require Moose::Meta::Role::Composite; my (@roles, %role_params); while (@role_specs) { my ($role, $params) = @{ splice @role_specs, 0, 1 }; my $requested_role = blessed $role ? $role : Class::MOP::class_of($role); my $actual_role = $requested_role->_role_for_combination($params); push @roles => $actual_role; next unless defined $params; $role_params{$actual_role->name} = $params; } my $c = Moose::Meta::Role::Composite->new(roles => \@roles); return $c->apply_params(\%role_params); } sub _role_for_combination { my ($self, $params) = @_; return $self; } sub create { my ( $role, $package_name, %options ) = @_; $options{package} = $package_name; (ref $options{attributes} eq 'HASH') || confess "You must pass a HASH ref of attributes" if exists $options{attributes}; (ref $options{methods} eq 'HASH') || confess "You must pass a HASH ref of methods" if exists $options{methods}; my (%initialize_options) = %options; delete @initialize_options{qw( package attributes methods version authority )}; my $meta = $role->initialize( $package_name => %initialize_options ); $meta->_instantiate_module( $options{version}, $options{authority} ); # FIXME totally lame $meta->add_method('meta' => sub { $role->initialize(ref($_[0]) || $_[0]); }); if (exists $options{attributes}) { foreach my $attribute_name (keys %{$options{attributes}}) { my $attr = $options{attributes}->{$attribute_name}; $meta->add_attribute( $attribute_name => blessed $attr ? $attr : %{$attr} ); } } if (exists $options{methods}) { foreach my $method_name (keys %{$options{methods}}) { $meta->add_method($method_name, $options{methods}->{$method_name}); } } Class::MOP::weaken_metaclass($meta->name) if $meta->is_anon_role; return $meta; } sub consumers { my $self = shift; my @consumers; for my $meta (Class::MOP::get_all_metaclass_instances) { next if $meta->name eq $self->name; next unless $meta->isa('Moose::Meta::Class') || $meta->isa('Moose::Meta::Role'); push @consumers, $meta->name if $meta->does_role($self->name); } return @consumers; } # anonymous roles. most of it is copied straight out of Class::MOP::Class. # an intrepid hacker might find great riches if he unifies this code with that # code in Class::MOP::Module or Class::MOP::Package { # NOTE: # this should be sufficient, if you have a # use case where it is not, write a test and # I will change it. my $ANON_ROLE_SERIAL = 0; # NOTE: # we need a sufficiently annoying prefix # this should suffice for now, this is # used in a couple of places below, so # need to put it up here for now. my $ANON_ROLE_PREFIX = 'Moose::Meta::Role::__ANON__::SERIAL::'; sub is_anon_role { my $self = shift; no warnings 'uninitialized'; $self->name =~ /^$ANON_ROLE_PREFIX/; } sub create_anon_role { my ($role, %options) = @_; my $package_name = $ANON_ROLE_PREFIX . ++$ANON_ROLE_SERIAL; return $role->create($package_name, %options); } # NOTE: # this will only get called for # anon-roles, all other calls # are assumed to occur during # global destruction and so don't # really need to be handled explicitly sub DESTROY { my $self = shift; return if in_global_destruction(); # it'll happen soon anyway and this just makes things more complicated no warnings 'uninitialized'; return unless $self->name =~ /^$ANON_ROLE_PREFIX/; # XXX: is this necessary for us? I don't understand what it's doing # -sartak # Moose does a weird thing where it replaces the metaclass for # class when fixing metaclass incompatibility. In that case, # we don't want to clean out the namespace now. We can detect # that because Moose will explicitly update the singleton # cache in Class::MOP. #my $current_meta = Class::MOP::get_metaclass_by_name($self->name); #return if $current_meta ne $self; my ($serial_id) = ($self->name =~ /^$ANON_ROLE_PREFIX(\d+)/); no strict 'refs'; foreach my $key (keys %{$ANON_ROLE_PREFIX . $serial_id}) { delete ${$ANON_ROLE_PREFIX . $serial_id}{$key}; } delete ${'main::' . $ANON_ROLE_PREFIX}{$serial_id . '::'}; } } ##################################################################### ## NOTE: ## This is Moose::Meta::Role as defined by Moose (plus the use of ## MooseX::AttributeHelpers module). It is here as a reference to ## make it easier to see what is happening above with all the meta ## programming. - SL ##################################################################### # # has 'roles' => ( # metaclass => 'Array', # reader => 'get_roles', # isa => 'ArrayRef[Moose::Meta::Role]', # default => sub { [] }, # provides => { # 'push' => 'add_role', # } # ); # # has 'excluded_roles_map' => ( # metaclass => 'Hash', # reader => 'get_excluded_roles_map', # isa => 'HashRef[Str]', # provides => { # # Not exactly set, cause it sets multiple # 'set' => 'add_excluded_roles', # 'keys' => 'get_excluded_roles_list', # 'exists' => 'excludes_role', # } # ); # # has 'required_methods' => ( # metaclass => 'Hash', # reader => 'get_required_methods_map', # isa => 'HashRef[Moose::Meta::Role::Method::Required]', # provides => { # # not exactly set, or delete since it works for multiple # 'set' => 'add_required_methods', # 'delete' => 'remove_required_methods', # 'keys' => 'get_required_method_list', # 'exists' => 'requires_method', # } # ); # # # the before, around and after modifiers are # # HASH keyed by method-name, with ARRAY of # # CODE refs to apply in that order # # has 'before_method_modifiers' => ( # metaclass => 'Hash', # reader => 'get_before_method_modifiers_map', # isa => 'HashRef[ArrayRef[CodeRef]]', # provides => { # 'keys' => 'get_before_method_modifiers', # 'exists' => 'has_before_method_modifiers', # # This actually makes sure there is an # # ARRAY at the given key, and pushed onto # # it. It also checks for duplicates as well # # 'add' => 'add_before_method_modifier' # } # ); # # has 'after_method_modifiers' => ( # metaclass => 'Hash', # reader =>'get_after_method_modifiers_map', # isa => 'HashRef[ArrayRef[CodeRef]]', # provides => { # 'keys' => 'get_after_method_modifiers', # 'exists' => 'has_after_method_modifiers', # # This actually makes sure there is an # # ARRAY at the given key, and pushed onto # # it. It also checks for duplicates as well # # 'add' => 'add_after_method_modifier' # } # ); # # has 'around_method_modifiers' => ( # metaclass => 'Hash', # reader =>'get_around_method_modifiers_map', # isa => 'HashRef[ArrayRef[CodeRef]]', # provides => { # 'keys' => 'get_around_method_modifiers', # 'exists' => 'has_around_method_modifiers', # # This actually makes sure there is an # # ARRAY at the given key, and pushed onto # # it. It also checks for duplicates as well # # 'add' => 'add_around_method_modifier' # } # ); # # # override is similar to the other modifiers # # except that it is not an ARRAY of code refs # # but instead just a single name->code mapping # # has 'override_method_modifiers' => ( # metaclass => 'Hash', # reader =>'get_override_method_modifiers_map', # isa => 'HashRef[CodeRef]', # provides => { # 'keys' => 'get_override_method_modifier', # 'exists' => 'has_override_method_modifier', # 'add' => 'add_override_method_modifier', # checks for local method .. # } # ); # ##################################################################### 1; __END__ =pod =head1 NAME Moose::Meta::Role - The Moose Role metaclass =head1 DESCRIPTION This class is a subclass of L<Class::MOP::Module> that provides additional Moose-specific functionality. It's API looks a lot like L<Moose::Meta::Class>, but internally it implements many things differently. This may change in the future. =head1 INHERITANCE C<Moose::Meta::Role> is a subclass of L<Class::MOP::Module>. =head1 METHODS =head2 Construction =over 4 =item B<< Moose::Meta::Role->initialize($role_name) >> This method creates a new role object with the provided name. =item B<< Moose::Meta::Role->combine( [ $role => { ... } ], [ $role ], ... ) >> This method accepts a list of array references. Each array reference should contain a role name or L<Moose::Meta::Role> object as its first element. The second element is an optional hash reference. The hash reference can contain C<-excludes> and C<-alias> keys to control how methods are composed from the role. The return value is a new L<Moose::Meta::Role::Composite> that represents the combined roles. =item B<< $metarole->composition_class_roles >> When combining multiple roles using C<combine>, this method is used to obtain a list of role names to be applied to the L<Moose::Meta::Role::Composite> instance returned by C<combine>. The default implementation returns an empty list. Extensions that need to hook into role combination may wrap this method to return additional role names. =item B<< Moose::Meta::Role->create($name, %options) >> This method is identical to the L<Moose::Meta::Class> C<create> method. =item B<< Moose::Meta::Role->create_anon_role >> This method is identical to the L<Moose::Meta::Class> C<create_anon_class> method. =item B<< $metarole->is_anon_role >> Returns true if the role is an anonymous role. =item B<< $metarole->consumers >> Returns a list of names of classes and roles which consume this role. =back =head2 Role application =over 4 =item B<< $metarole->apply( $thing, @options ) >> This method applies a role to the given C<$thing>. That can be another L<Moose::Meta::Role>, object, a L<Moose::Meta::Class> object, or a (non-meta) object instance. The options are passed directly to the constructor for the appropriate L<Moose::Meta::Role::Application> subclass. Note that this will apply the role even if the C<$thing> in question already C<does> this role. L<Moose::Util/does_role> is a convenient wrapper for finding out if role application is necessary. =back =head2 Roles and other roles =over 4 =item B<< $metarole->get_roles >> This returns an array reference of roles which this role does. This list may include duplicates. =item B<< $metarole->calculate_all_roles >> This returns a I<unique> list of all roles that this role does, and all the roles that its roles do. =item B<< $metarole->does_role($role) >> Given a role I<name> or L<Moose::Meta::Role> object, returns true if this role does the given role. =item B<< $metarole->add_role($role) >> Given a L<Moose::Meta::Role> object, this adds the role to the list of roles that the role does. =item B<< $metarole->get_excluded_roles_list >> Returns a list of role names which this role excludes. =item B<< $metarole->excludes_role($role_name) >> Given a role I<name>, returns true if this role excludes the named role. =item B<< $metarole->add_excluded_roles(@role_names) >> Given one or more role names, adds those roles to the list of excluded roles. =back =head2 Methods The methods for dealing with a role's methods are all identical in API and behavior to the same methods in L<Class::MOP::Class>. =over 4 =item B<< $metarole->method_metaclass >> Returns the method metaclass name for the role. This defaults to L<Moose::Meta::Role::Method>. =item B<< $metarole->get_method($name) >> =item B<< $metarole->has_method($name) >> =item B<< $metarole->add_method( $name, $body ) >> =item B<< $metarole->get_method_list >> =item B<< $metarole->find_method_by_name($name) >> These methods are all identical to the methods of the same name in L<Class::MOP::Package> =back =head2 Attributes As with methods, the methods for dealing with a role's attribute are all identical in API and behavior to the same methods in L<Class::MOP::Class>. However, attributes stored in this class are I<not> stored as objects. Rather, the attribute definition is stored as a hash reference. When a role is composed into a class, this hash reference is passed directly to the metaclass's C<add_attribute> method. This is quite likely to change in the future. =over 4 =item B<< $metarole->get_attribute($attribute_name) >> =item B<< $metarole->has_attribute($attribute_name) >> =item B<< $metarole->get_attribute_list >> =item B<< $metarole->add_attribute($name, %options) >> =item B<< $metarole->remove_attribute($attribute_name) >> =back =head2 Required methods =over 4 =item B<< $metarole->get_required_method_list >> Returns the list of methods required by the role. =item B<< $metarole->requires_method($name) >> Returns true if the role requires the named method. =item B<< $metarole->add_required_methods(@names) >> Adds the named methods to the role's list of required methods. =item B<< $metarole->remove_required_methods(@names) >> Removes the named methods from the role's list of required methods. =item B<< $metarole->add_conflicting_method(%params) >> Instantiate the parameters as a L<Moose::Meta::Role::Method::Conflicting> object, then add it to the required method list. =back =head2 Method modifiers These methods act like their counterparts in L<Class::MOP::Class> and L<Moose::Meta::Class>. However, method modifiers are simply stored internally, and are not applied until the role itself is applied to a class. =over 4 =item B<< $metarole->add_after_method_modifier($method_name, $method) >> =item B<< $metarole->add_around_method_modifier($method_name, $method) >> =item B<< $metarole->add_before_method_modifier($method_name, $method) >> =item B<< $metarole->add_override_method_modifier($method_name, $method) >> These methods all add an appropriate modifier to the internal list of modifiers. =item B<< $metarole->has_after_method_modifiers >> =item B<< $metarole->has_around_method_modifiers >> =item B<< $metarole->has_before_method_modifiers >> =item B<< $metarole->has_override_method_modifier >> Return true if the role has any modifiers of the given type. =item B<< $metarole->get_after_method_modifiers($method_name) >> =item B<< $metarole->get_around_method_modifiers($method_name) >> =item B<< $metarole->get_before_method_modifiers($method_name) >> Given a method name, returns a list of the appropriate modifiers for that method. =item B<< $metarole->get_override_method_modifier($method_name) >> Given a method name, returns the override method modifier for that method, if it has one. =back =head2 Introspection =over 4 =item B<< Moose::Meta::Role->meta >> This will return a L<Class::MOP::Class> instance for this class. =back =head1 BUGS See L<Moose/BUGS> for details on reporting bugs. =head1 AUTHOR Stevan Little E<lt>stevan@iinteractive.comE<gt> =head1 COPYRIGHT AND LICENSE Copyright 2006-2010 by Infinity Interactive, Inc. L<http://www.iinteractive.com> This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself. =cut