2 package Class::MOP::Class;
7 use Class::MOP::Instance;
8 use Class::MOP::Method::Wrapped;
9 use Class::MOP::Method::Accessor;
10 use Class::MOP::Method::Constructor;
11 use Class::MOP::MiniTrait;
14 use Scalar::Util 'blessed', 'reftype', 'weaken';
15 use Sub::Name 'subname';
16 use Devel::GlobalDestruction 'in_global_destruction';
18 use List::MoreUtils 'all';
20 our $VERSION = '1.12';
21 $VERSION = eval $VERSION;
22 our $AUTHORITY = 'cpan:STEVAN';
24 use base 'Class::MOP::Module',
25 'Class::MOP::Mixin::HasAttributes',
26 'Class::MOP::Mixin::HasMethods';
36 $package_name = shift;
39 $package_name = $options{package};
42 ($package_name && !ref($package_name))
43 || confess "You must pass a package name and it cannot be blessed";
45 return Class::MOP::get_metaclass_by_name($package_name)
46 || $class->_construct_class_instance(package => $package_name, @_);
50 my ( $class, @args ) = @_;
51 unshift @args, "package" if @args % 2;
53 my $old_metaclass = blessed($options{package})
55 : Class::MOP::get_metaclass_by_name($options{package});
56 $options{weaken} = Class::MOP::metaclass_is_weak($old_metaclass->name)
57 if !exists $options{weaken}
58 && blessed($old_metaclass)
59 && $old_metaclass->isa('Class::MOP::Class');
60 $old_metaclass->_remove_generated_metaobjects
61 if $old_metaclass && $old_metaclass->isa('Class::MOP::Class');
62 my $new_metaclass = $class->SUPER::reinitialize(%options);
63 $new_metaclass->_restore_metaobjects_from($old_metaclass)
64 if $old_metaclass && $old_metaclass->isa('Class::MOP::Class');
65 return $new_metaclass;
68 # NOTE: (meta-circularity)
69 # this is a special form of _construct_instance
70 # (see below), which is used to construct class
71 # meta-object instances for any Class::MOP::*
72 # class. All other classes will use the more
73 # normal &construct_instance.
74 sub _construct_class_instance {
76 my $options = @_ == 1 ? $_[0] : {@_};
77 my $package_name = $options->{package};
78 (defined $package_name && $package_name)
79 || confess "You must pass a package name";
81 # return the metaclass if we have it cached,
82 # and it is still defined (it has not been
83 # reaped by DESTROY yet, which can happen
84 # annoyingly enough during global destruction)
86 if (defined(my $meta = Class::MOP::get_metaclass_by_name($package_name))) {
92 ? $class->_real_ref_name
95 # now create the metaclass
97 if ($class eq 'Class::MOP::Class') {
98 $meta = $class->_new($options);
102 # it is safe to use meta here because
103 # class will always be a subclass of
104 # Class::MOP::Class, which defines meta
105 $meta = $class->meta->_construct_instance($options)
108 # and check the metaclass compatibility
109 $meta->_check_metaclass_compatibility();
111 Class::MOP::store_metaclass_by_name($package_name, $meta);
114 # we need to weaken any anon classes
115 # so that they can call DESTROY properly
116 Class::MOP::weaken_metaclass($package_name) if $options->{weaken};
124 # NOTE: we need to deal with the possibility of class immutability here,
125 # and then get the name of the class appropriately
126 return $self->is_immutable
127 ? $self->_get_mutable_metaclass_name()
134 return Class::MOP::Class->initialize($class)->new_object(@_)
135 if $class ne __PACKAGE__;
137 my $options = @_ == 1 ? $_[0] : {@_};
140 # inherited from Class::MOP::Package
141 'package' => $options->{package},
144 # since the following attributes will
145 # actually be loaded from the symbol
146 # table, and actually bypass the instance
147 # entirely, we can just leave these things
148 # listed here for reference, because they
149 # should not actually have a value associated
151 'namespace' => \undef,
154 # inherited from Class::MOP::Module
156 'authority' => \undef,
158 # defined in Class::MOP::Class
159 'superclasses' => \undef,
162 'attribute_metaclass' =>
163 ( $options->{'attribute_metaclass'} || 'Class::MOP::Attribute' ),
164 'method_metaclass' =>
165 ( $options->{'method_metaclass'} || 'Class::MOP::Method' ),
166 'wrapped_method_metaclass' => (
167 $options->{'wrapped_method_metaclass'}
168 || 'Class::MOP::Method::Wrapped'
170 'instance_metaclass' =>
171 ( $options->{'instance_metaclass'} || 'Class::MOP::Instance' ),
172 'immutable_trait' => (
173 $options->{'immutable_trait'}
174 || 'Class::MOP::Class::Immutable::Trait'
176 'constructor_name' => ( $options->{constructor_name} || 'new' ),
177 'constructor_class' => (
178 $options->{constructor_class} || 'Class::MOP::Method::Constructor'
180 'destructor_class' => $options->{destructor_class},
184 sub reset_package_cache_flag { (shift)->{'_package_cache_flag'} = undef }
185 sub update_package_cache_flag {
188 # we can manually update the cache number
189 # since we are actually adding the method
190 # to our cache as well. This avoids us
191 # having to regenerate the method_map.
193 $self->{'_package_cache_flag'} = Class::MOP::check_package_cache_flag($self->name);
196 ## Metaclass compatibility
198 my %base_metaclass = (
199 attribute_metaclass => 'Class::MOP::Attribute',
200 method_metaclass => 'Class::MOP::Method',
201 wrapped_method_metaclass => 'Class::MOP::Method::Wrapped',
202 instance_metaclass => 'Class::MOP::Instance',
203 constructor_class => 'Class::MOP::Method::Constructor',
204 destructor_class => 'Class::MOP::Method::Destructor',
207 sub _base_metaclasses { %base_metaclass }
210 sub _check_metaclass_compatibility {
213 my @superclasses = $self->superclasses
216 $self->_fix_metaclass_incompatibility(@superclasses);
218 my %base_metaclass = $self->_base_metaclasses;
220 # this is always okay ...
222 if ref($self) eq 'Class::MOP::Class'
224 my $meta = $self->$_;
225 !defined($meta) || $meta eq $base_metaclass{$_};
227 keys %base_metaclass;
229 for my $superclass (@superclasses) {
230 $self->_check_class_metaclass_compatibility($superclass);
233 for my $metaclass_type ( keys %base_metaclass ) {
234 next unless defined $self->$metaclass_type;
235 for my $superclass (@superclasses) {
236 $self->_check_single_metaclass_compatibility( $metaclass_type,
242 sub _check_class_metaclass_compatibility {
244 my ( $superclass_name ) = @_;
246 if (!$self->_class_metaclass_is_compatible($superclass_name)) {
247 my $super_meta = Class::MOP::get_metaclass_by_name($superclass_name);
249 my $super_meta_type = $super_meta->_real_ref_name;
251 confess "The metaclass of " . $self->name . " ("
252 . (ref($self)) . ")" . " is not compatible with "
253 . "the metaclass of its superclass, "
254 . $superclass_name . " (" . ($super_meta_type) . ")";
258 sub _class_metaclass_is_compatible {
260 my ( $superclass_name ) = @_;
262 my $super_meta = Class::MOP::get_metaclass_by_name($superclass_name)
265 my $super_meta_name = $super_meta->_real_ref_name;
267 return $self->_is_compatible_with($super_meta_name);
270 sub _check_single_metaclass_compatibility {
272 my ( $metaclass_type, $superclass_name ) = @_;
274 if (!$self->_single_metaclass_is_compatible($metaclass_type, $superclass_name)) {
275 my $super_meta = Class::MOP::get_metaclass_by_name($superclass_name);
276 my $metaclass_type_name = $metaclass_type;
277 $metaclass_type_name =~ s/_(?:meta)?class$//;
278 $metaclass_type_name =~ s/_/ /g;
279 confess "The $metaclass_type_name metaclass for "
280 . $self->name . " (" . ($self->$metaclass_type)
281 . ")" . " is not compatible with the "
282 . "$metaclass_type_name metaclass of its "
283 . "superclass, $superclass_name ("
284 . ($super_meta->$metaclass_type) . ")";
288 sub _single_metaclass_is_compatible {
290 my ( $metaclass_type, $superclass_name ) = @_;
292 my $super_meta = Class::MOP::get_metaclass_by_name($superclass_name)
295 # for instance, Moose::Meta::Class has a error_class attribute, but
296 # Class::MOP::Class doesn't - this shouldn't be an error
297 return 1 unless $super_meta->can($metaclass_type);
298 # for instance, Moose::Meta::Class has a destructor_class, but
299 # Class::MOP::Class doesn't - this shouldn't be an error
300 return 1 unless defined $super_meta->$metaclass_type;
301 # if metaclass is defined in superclass but not here, it's not compatible
302 # this is a really odd case
303 return 0 unless defined $self->$metaclass_type;
305 return $self->$metaclass_type->_is_compatible_with($super_meta->$metaclass_type);
308 sub _fix_metaclass_incompatibility {
310 my @supers = map { Class::MOP::Class->initialize($_) } @_;
313 for my $super (@supers) {
315 if $self->_can_fix_metaclass_incompatibility($super);
317 return unless $necessary;
319 for my $super (@supers) {
320 if (!$self->_class_metaclass_is_compatible($super->name)) {
321 $self->_fix_class_metaclass_incompatibility($super);
325 my %base_metaclass = $self->_base_metaclasses;
326 for my $metaclass_type (keys %base_metaclass) {
327 for my $super (@supers) {
328 if (!$self->_single_metaclass_is_compatible($metaclass_type, $super->name)) {
329 $self->_fix_single_metaclass_incompatibility(
330 $metaclass_type, $super
337 sub _can_fix_metaclass_incompatibility {
339 my ($super_meta) = @_;
341 return 1 if $self->_class_metaclass_can_be_made_compatible($super_meta);
343 my %base_metaclass = $self->_base_metaclasses;
344 for my $metaclass_type (keys %base_metaclass) {
345 return 1 if $self->_single_metaclass_can_be_made_compatible($super_meta, $metaclass_type);
351 sub _class_metaclass_can_be_made_compatible {
353 my ($super_meta) = @_;
355 return $self->_can_be_made_compatible_with($super_meta->_real_ref_name);
358 sub _single_metaclass_can_be_made_compatible {
360 my ($super_meta, $metaclass_type) = @_;
362 my $specific_meta = $self->$metaclass_type;
364 return unless $super_meta->can($metaclass_type);
365 my $super_specific_meta = $super_meta->$metaclass_type;
367 # for instance, Moose::Meta::Class has a destructor_class, but
368 # Class::MOP::Class doesn't - this shouldn't be an error
369 return unless defined $super_specific_meta;
371 # if metaclass is defined in superclass but not here, it's fixable
372 # this is a really odd case
373 return 1 unless defined $specific_meta;
375 return 1 if $specific_meta->_can_be_made_compatible_with($super_specific_meta);
378 sub _fix_class_metaclass_incompatibility {
380 my ( $super_meta ) = @_;
382 if ($self->_class_metaclass_can_be_made_compatible($super_meta)) {
384 || confess "Can't fix metaclass incompatibility for "
386 . " because it is not pristine.";
388 my $super_meta_name = $super_meta->_real_ref_name;
390 $self->_make_compatible_with($super_meta_name);
394 sub _fix_single_metaclass_incompatibility {
396 my ( $metaclass_type, $super_meta ) = @_;
398 if ($self->_single_metaclass_can_be_made_compatible($super_meta, $metaclass_type)) {
400 || confess "Can't fix metaclass incompatibility for "
402 . " because it is not pristine.";
404 my $new_metaclass = $self->$metaclass_type
405 ? $self->$metaclass_type->_get_compatible_metaclass($super_meta->$metaclass_type)
406 : $super_meta->$metaclass_type;
407 $self->{$metaclass_type} = $new_metaclass;
411 sub _restore_metaobjects_from {
415 $self->_restore_metamethods_from($old_meta);
416 $self->_restore_metaattributes_from($old_meta);
419 sub _remove_generated_metaobjects {
422 for my $attr (map { $self->get_attribute($_) } $self->get_attribute_list) {
423 $attr->remove_accessors;
431 # this should be sufficient, if you have a
432 # use case where it is not, write a test and
434 my $ANON_CLASS_SERIAL = 0;
437 # we need a sufficiently annoying prefix
438 # this should suffice for now, this is
439 # used in a couple of places below, so
440 # need to put it up here for now.
441 my $ANON_CLASS_PREFIX = 'Class::MOP::Class::__ANON__::SERIAL::';
445 no warnings 'uninitialized';
446 $self->name =~ /^$ANON_CLASS_PREFIX/o;
449 sub create_anon_class {
450 my ($class, %options) = @_;
451 $options{weaken} = 1 unless exists $options{weaken};
452 my $package_name = $ANON_CLASS_PREFIX . ++$ANON_CLASS_SERIAL;
453 return $class->create($package_name, %options);
457 # this will only get called for
458 # anon-classes, all other calls
459 # are assumed to occur during
460 # global destruction and so don't
461 # really need to be handled explicitly
465 return if in_global_destruction(); # it'll happen soon anyway and this just makes things more complicated
467 no warnings 'uninitialized';
468 my $name = $self->name;
469 return unless $name =~ /^$ANON_CLASS_PREFIX/o;
471 # Moose does a weird thing where it replaces the metaclass for
472 # class when fixing metaclass incompatibility. In that case,
473 # we don't want to clean out the namespace now. We can detect
474 # that because Moose will explicitly update the singleton
475 # cache in Class::MOP.
476 my $current_meta = Class::MOP::get_metaclass_by_name($name);
477 return if $current_meta ne $self;
479 my ($serial_id) = ($name =~ /^$ANON_CLASS_PREFIX(\d+)/o);
481 @{$name . '::ISA'} = ();
482 %{$name . '::'} = ();
483 delete ${$ANON_CLASS_PREFIX}{$serial_id . '::'};
485 Class::MOP::remove_metaclass_by_name($name);
490 # creating classes with MOP ...
493 my ( $class, @args ) = @_;
495 unshift @args, 'package' if @args % 2 == 1;
497 my (%options) = @args;
498 my $package_name = $options{package};
500 (ref $options{superclasses} eq 'ARRAY')
501 || confess "You must pass an ARRAY ref of superclasses"
502 if exists $options{superclasses};
504 (ref $options{attributes} eq 'ARRAY')
505 || confess "You must pass an ARRAY ref of attributes"
506 if exists $options{attributes};
508 (ref $options{methods} eq 'HASH')
509 || confess "You must pass a HASH ref of methods"
510 if exists $options{methods};
512 $options{meta_name} = 'meta'
513 unless exists $options{meta_name};
515 my (%initialize_options) = @args;
516 delete @initialize_options{qw(
525 my $meta = $class->initialize( $package_name => %initialize_options );
527 $meta->_instantiate_module( $options{version}, $options{authority} );
529 $meta->_add_meta_method($options{meta_name})
530 if defined $options{meta_name};
532 $meta->superclasses(@{$options{superclasses}})
533 if exists $options{superclasses};
535 # process attributes first, so that they can
536 # install accessors, but locally defined methods
537 # can then overwrite them. It is maybe a little odd, but
538 # I think this should be the order of things.
539 if (exists $options{attributes}) {
540 foreach my $attr (@{$options{attributes}}) {
541 $meta->add_attribute($attr);
544 if (exists $options{methods}) {
545 foreach my $method_name (keys %{$options{methods}}) {
546 $meta->add_method($method_name, $options{methods}->{$method_name});
555 # all these attribute readers will be bootstrapped
556 # away in the Class::MOP bootstrap section
558 sub instance_metaclass { $_[0]->{'instance_metaclass'} }
559 sub immutable_trait { $_[0]->{'immutable_trait'} }
560 sub constructor_class { $_[0]->{'constructor_class'} }
561 sub constructor_name { $_[0]->{'constructor_name'} }
562 sub destructor_class { $_[0]->{'destructor_class'} }
564 # Instance Construction & Cloning
570 # we need to protect the integrity of the
571 # Class::MOP::Class singletons here, so we
572 # delegate this to &construct_class_instance
573 # which will deal with the singletons
574 return $class->_construct_class_instance(@_)
575 if $class->name->isa('Class::MOP::Class');
576 return $class->_construct_instance(@_);
579 sub _construct_instance {
581 my $params = @_ == 1 ? $_[0] : {@_};
582 my $meta_instance = $class->get_meta_instance();
584 # the code below is almost certainly incorrect
585 # but this is foreign inheritance, so we might
586 # have to kludge it in the end.
588 if (my $instance_class = blessed($params->{__INSTANCE__})) {
589 ($instance_class eq $class->name)
590 || confess "Objects passed as the __INSTANCE__ parameter must "
591 . "already be blessed into the correct class, but "
592 . "$params->{__INSTANCE__} is not a " . $class->name;
593 $instance = $params->{__INSTANCE__};
595 elsif (exists $params->{__INSTANCE__}) {
596 confess "The __INSTANCE__ parameter must be a blessed reference, not "
597 . $params->{__INSTANCE__};
600 $instance = $meta_instance->create_instance();
602 foreach my $attr ($class->get_all_attributes()) {
603 $attr->initialize_instance_slot($meta_instance, $instance, $params);
605 if (Class::MOP::metaclass_is_weak($class->name)) {
606 $meta_instance->_set_mop_slot($instance, $class);
612 sub get_meta_instance {
614 $self->{'_meta_instance'} ||= $self->_create_meta_instance();
617 sub _create_meta_instance {
620 my $instance = $self->instance_metaclass->new(
621 associated_metaclass => $self,
622 attributes => [ $self->get_all_attributes() ],
625 $self->add_meta_instance_dependencies()
626 if $instance->is_dependent_on_superclasses();
631 sub inline_create_instance {
634 return $self->get_meta_instance->inline_create_instance(@_);
637 sub inline_rebless_instance {
640 return $self->get_meta_instance->inline_rebless_instance_structure(@_);
643 sub _inline_get_mop_slot {
646 return $self->get_meta_instance->_inline_get_mop_slot(@_);
649 sub _inline_set_mop_slot {
652 return $self->get_meta_instance->_inline_set_mop_slot(@_);
655 sub _inline_clear_mop_slot {
658 return $self->get_meta_instance->_inline_clear_mop_slot(@_);
663 my $instance = shift;
664 (blessed($instance) && $instance->isa($class->name))
665 || confess "You must pass an instance of the metaclass (" . (ref $class ? $class->name : $class) . "), not ($instance)";
668 # we need to protect the integrity of the
669 # Class::MOP::Class singletons here, they
670 # should not be cloned.
671 return $instance if $instance->isa('Class::MOP::Class');
672 $class->_clone_instance($instance, @_);
675 sub _clone_instance {
676 my ($class, $instance, %params) = @_;
678 || confess "You can only clone instances, ($instance) is not a blessed instance";
679 my $meta_instance = $class->get_meta_instance();
680 my $clone = $meta_instance->clone_instance($instance);
681 foreach my $attr ($class->get_all_attributes()) {
682 if ( defined( my $init_arg = $attr->init_arg ) ) {
683 if (exists $params{$init_arg}) {
684 $attr->set_value($clone, $params{$init_arg});
691 sub _force_rebless_instance {
692 my ($self, $instance, %params) = @_;
693 my $old_metaclass = Class::MOP::class_of($instance);
695 $old_metaclass->rebless_instance_away($instance, $self, %params)
698 my $meta_instance = $self->get_meta_instance;
700 if (Class::MOP::metaclass_is_weak($old_metaclass->name)) {
701 $meta_instance->_clear_mop_slot($instance);
705 # we use $_[1] here because of t/306_rebless_overload.t regressions on 5.8.8
706 $meta_instance->rebless_instance_structure($_[1], $self);
708 $self->_fixup_attributes_after_rebless($instance, $old_metaclass, %params);
710 if (Class::MOP::metaclass_is_weak($self->name)) {
711 $meta_instance->_set_mop_slot($instance, $self);
715 sub rebless_instance {
716 my ($self, $instance, %params) = @_;
717 my $old_metaclass = Class::MOP::class_of($instance);
719 my $old_class = $old_metaclass ? $old_metaclass->name : blessed($instance);
720 $self->name->isa($old_class)
721 || confess "You may rebless only into a subclass of ($old_class), of which (". $self->name .") isn't.";
723 $self->_force_rebless_instance($_[1], %params);
728 sub rebless_instance_back {
729 my ( $self, $instance ) = @_;
730 my $old_metaclass = Class::MOP::class_of($instance);
733 = $old_metaclass ? $old_metaclass->name : blessed($instance);
734 $old_class->isa( $self->name )
736 "You may rebless only into a superclass of ($old_class), of which ("
740 $self->_force_rebless_instance($_[1]);
745 sub rebless_instance_away {
746 # this intentionally does nothing, it is just a hook
749 sub _fixup_attributes_after_rebless {
751 my ($instance, $rebless_from, %params) = @_;
752 my $meta_instance = $self->get_meta_instance;
754 for my $attr ( $rebless_from->get_all_attributes ) {
755 next if $self->find_attribute_by_name( $attr->name );
756 $meta_instance->deinitialize_slot( $instance, $_ ) for $attr->slots;
759 foreach my $attr ( $self->get_all_attributes ) {
760 if ( $attr->has_value($instance) ) {
761 if ( defined( my $init_arg = $attr->init_arg ) ) {
762 $params{$init_arg} = $attr->get_value($instance)
763 unless exists $params{$init_arg};
766 $attr->set_value($instance, $attr->get_value($instance));
771 foreach my $attr ($self->get_all_attributes) {
772 $attr->initialize_instance_slot($meta_instance, $instance, \%params);
776 sub _attach_attribute {
777 my ($self, $attribute) = @_;
778 $attribute->attach_to_class($self);
781 sub _post_add_attribute {
782 my ( $self, $attribute ) = @_;
784 $self->invalidate_meta_instances;
786 # invalidate package flag here
789 $attribute->install_accessors;
792 $self->remove_attribute( $attribute->name );
797 sub remove_attribute {
800 my $removed_attribute = $self->SUPER::remove_attribute(@_)
803 $self->invalidate_meta_instances;
805 $removed_attribute->remove_accessors;
806 $removed_attribute->detach_from_class;
808 return$removed_attribute;
811 sub find_attribute_by_name {
812 my ( $self, $attr_name ) = @_;
814 foreach my $class ( $self->linearized_isa ) {
815 # fetch the meta-class ...
816 my $meta = Class::MOP::Class->initialize($class);
817 return $meta->get_attribute($attr_name)
818 if $meta->has_attribute($attr_name);
824 sub get_all_attributes {
826 my %attrs = map { %{ Class::MOP::Class->initialize($_)->_attribute_map } }
827 reverse $self->linearized_isa;
828 return values %attrs;
836 my $isa = $self->get_or_add_package_symbol(
837 { sigil => '@', type => 'ARRAY', name => 'ISA' } );
844 # on 5.8 and below, we need to call
845 # a method to get Perl to detect
846 # a cycle in the class hierarchy
847 my $class = $self->name;
851 # we need to check the metaclass
852 # compatibility here so that we can
853 # be sure that the superclass is
854 # not potentially creating an issues
855 # we don't know about
857 $self->_check_metaclass_compatibility();
858 $self->_superclasses_updated();
864 sub _superclasses_updated {
866 $self->update_meta_instance_dependencies();
867 # keep strong references to all our parents, so they don't disappear if
868 # they are anon classes and don't have any direct instances
869 $self->_superclass_metas(
870 map { Class::MOP::class_of($_) } $self->superclasses
874 sub _superclass_metas {
876 $self->{_superclass_metas} = [@_];
881 my $super_class = $self->name;
883 return @{ $super_class->mro::get_isarev() };
886 sub direct_subclasses {
888 my $super_class = $self->name;
893 } Class::MOP::Class->initialize($_)->superclasses
898 return @{ mro::get_linear_isa( (shift)->name ) };
901 sub class_precedence_list {
903 my $name = $self->name;
905 unless (Class::MOP::IS_RUNNING_ON_5_10()) {
907 # We need to check for circular inheritance here
908 # if we are are not on 5.10, cause 5.8 detects it
909 # late. This will do nothing if all is well, and
910 # blow up otherwise. Yes, it's an ugly hack, better
911 # suggestions are welcome.
913 ($name || return)->isa('This is a test for circular inheritance')
916 # if our mro is c3, we can
917 # just grab the linear_isa
918 if (mro::get_mro($name) eq 'c3') {
919 return @{ mro::get_linear_isa($name) }
923 # we can't grab the linear_isa for dfs
924 # since it has all the duplicates
929 Class::MOP::Class->initialize($_)->class_precedence_list()
930 } $self->superclasses()
938 my $fetch_and_prepare_method = sub {
939 my ($self, $method_name) = @_;
940 my $wrapped_metaclass = $self->wrapped_method_metaclass;
942 my $method = $self->get_method($method_name);
943 # if we dont have local ...
945 # try to find the next method
946 $method = $self->find_next_method_by_name($method_name);
947 # die if it does not exist
949 || confess "The method '$method_name' was not found in the inheritance hierarchy for " . $self->name;
950 # and now make sure to wrap it
951 # even if it is already wrapped
952 # because we need a new sub ref
953 $method = $wrapped_metaclass->wrap($method,
954 package_name => $self->name,
955 name => $method_name,
959 # now make sure we wrap it properly
960 $method = $wrapped_metaclass->wrap($method,
961 package_name => $self->name,
962 name => $method_name,
963 ) unless $method->isa($wrapped_metaclass);
965 $self->add_method($method_name => $method);
969 sub add_before_method_modifier {
970 my ($self, $method_name, $method_modifier) = @_;
971 (defined $method_name && length $method_name)
972 || confess "You must pass in a method name";
973 my $method = $fetch_and_prepare_method->($self, $method_name);
974 $method->add_before_modifier(
975 subname(':before' => $method_modifier)
979 sub add_after_method_modifier {
980 my ($self, $method_name, $method_modifier) = @_;
981 (defined $method_name && length $method_name)
982 || confess "You must pass in a method name";
983 my $method = $fetch_and_prepare_method->($self, $method_name);
984 $method->add_after_modifier(
985 subname(':after' => $method_modifier)
989 sub add_around_method_modifier {
990 my ($self, $method_name, $method_modifier) = @_;
991 (defined $method_name && length $method_name)
992 || confess "You must pass in a method name";
993 my $method = $fetch_and_prepare_method->($self, $method_name);
994 $method->add_around_modifier(
995 subname(':around' => $method_modifier)
1000 # the methods above used to be named like this:
1001 # ${pkg}::${method}:(before|after|around)
1002 # but this proved problematic when using one modifier
1003 # to wrap multiple methods (something which is likely
1004 # to happen pretty regularly IMO). So instead of naming
1005 # it like this, I have chosen to just name them purely
1006 # with their modifier names, like so:
1007 # :(before|after|around)
1008 # The fact is that in a stack trace, it will be fairly
1009 # evident from the context what method they are attached
1010 # to, and so don't need the fully qualified name.
1013 sub find_method_by_name {
1014 my ($self, $method_name) = @_;
1015 (defined $method_name && length $method_name)
1016 || confess "You must define a method name to find";
1017 foreach my $class ($self->linearized_isa) {
1018 my $method = Class::MOP::Class->initialize($class)->get_method($method_name);
1019 return $method if defined $method;
1024 sub get_all_methods {
1028 for my $class ( reverse $self->linearized_isa ) {
1029 my $meta = Class::MOP::Class->initialize($class);
1031 $methods{ $_->name } = $_ for $meta->_get_local_methods;
1034 return values %methods;
1037 sub get_all_method_names {
1040 return grep { !$uniq{$_}++ } map { Class::MOP::Class->initialize($_)->get_method_list } $self->linearized_isa;
1043 sub find_all_methods_by_name {
1044 my ($self, $method_name) = @_;
1045 (defined $method_name && length $method_name)
1046 || confess "You must define a method name to find";
1048 foreach my $class ($self->linearized_isa) {
1049 # fetch the meta-class ...
1050 my $meta = Class::MOP::Class->initialize($class);
1052 name => $method_name,
1054 code => $meta->get_method($method_name)
1055 } if $meta->has_method($method_name);
1060 sub find_next_method_by_name {
1061 my ($self, $method_name) = @_;
1062 (defined $method_name && length $method_name)
1063 || confess "You must define a method name to find";
1064 my @cpl = $self->linearized_isa;
1065 shift @cpl; # discard ourselves
1066 foreach my $class (@cpl) {
1067 my $method = Class::MOP::Class->initialize($class)->get_method($method_name);
1068 return $method if defined $method;
1073 sub update_meta_instance_dependencies {
1076 if ( $self->{meta_instance_dependencies} ) {
1077 return $self->add_meta_instance_dependencies;
1081 sub add_meta_instance_dependencies {
1084 $self->remove_meta_instance_dependencies;
1086 my @attrs = $self->get_all_attributes();
1089 my @classes = grep { not $seen{ $_->name }++ }
1090 map { $_->associated_class } @attrs;
1092 foreach my $class (@classes) {
1093 $class->add_dependent_meta_instance($self);
1096 $self->{meta_instance_dependencies} = \@classes;
1099 sub remove_meta_instance_dependencies {
1102 if ( my $classes = delete $self->{meta_instance_dependencies} ) {
1103 foreach my $class (@$classes) {
1104 $class->remove_dependent_meta_instance($self);
1114 sub add_dependent_meta_instance {
1115 my ( $self, $metaclass ) = @_;
1116 push @{ $self->{dependent_meta_instances} }, $metaclass;
1119 sub remove_dependent_meta_instance {
1120 my ( $self, $metaclass ) = @_;
1121 my $name = $metaclass->name;
1122 @$_ = grep { $_->name ne $name } @$_
1123 for $self->{dependent_meta_instances};
1126 sub invalidate_meta_instances {
1128 $_->invalidate_meta_instance()
1129 for $self, @{ $self->{dependent_meta_instances} };
1132 sub invalidate_meta_instance {
1134 undef $self->{_meta_instance};
1137 # check if we can reinitialize
1141 # if any local attr is defined
1142 return if $self->get_attribute_list;
1144 # or any non-declared methods
1145 for my $method ( map { $self->get_method($_) } $self->get_method_list ) {
1146 return if $method->isa("Class::MOP::Method::Generated");
1147 # FIXME do we need to enforce this too? return unless $method->isa( $self->method_metaclass );
1155 sub is_mutable { 1 }
1156 sub is_immutable { 0 }
1158 sub immutable_options { %{ $_[0]{__immutable}{options} || {} } }
1160 sub _immutable_options {
1161 my ( $self, @args ) = @_;
1164 inline_accessors => 1,
1165 inline_constructor => 1,
1166 inline_destructor => 0,
1168 immutable_trait => $self->immutable_trait,
1169 constructor_name => $self->constructor_name,
1170 constructor_class => $self->constructor_class,
1171 destructor_class => $self->destructor_class,
1176 sub make_immutable {
1177 my ( $self, @args ) = @_;
1179 if ( $self->is_mutable ) {
1180 $self->_initialize_immutable( $self->_immutable_options(@args) );
1181 $self->_rebless_as_immutable(@args);
1192 if ( $self->is_immutable ) {
1193 my @args = $self->immutable_options;
1194 $self->_rebless_as_mutable();
1195 $self->_remove_inlined_code(@args);
1196 delete $self->{__immutable};
1204 sub _rebless_as_immutable {
1205 my ( $self, @args ) = @_;
1207 $self->{__immutable}{original_class} = ref $self;
1209 bless $self => $self->_immutable_metaclass(@args);
1212 sub _immutable_metaclass {
1213 my ( $self, %args ) = @_;
1215 if ( my $class = $args{immutable_metaclass} ) {
1219 my $trait = $args{immutable_trait} = $self->immutable_trait
1220 || confess "no immutable trait specified for $self";
1222 my $meta = $self->meta;
1223 my $meta_attr = $meta->find_attribute_by_name("immutable_trait");
1227 if ( $meta_attr and $trait eq $meta_attr->default ) {
1228 # if the trait is the same as the default we try and pick a
1229 # predictable name for the immutable metaclass
1230 $class_name = 'Class::MOP::Class::Immutable::' . ref($self);
1233 $class_name = join '::', 'Class::MOP::Class::Immutable::CustomTrait',
1234 $trait, 'ForMetaClass', ref($self);
1238 if Class::MOP::is_class_loaded($class_name);
1240 # If the metaclass is a subclass of CMOP::Class which has had
1241 # metaclass roles applied (via Moose), then we want to make sure
1242 # that we preserve that anonymous class (see Fey::ORM for an
1243 # example of where this matters).
1244 my $meta_name = $meta->_real_ref_name;
1246 my $immutable_meta = $meta_name->create(
1248 superclasses => [ ref $self ],
1251 Class::MOP::MiniTrait::apply( $immutable_meta, $trait );
1253 $immutable_meta->make_immutable(
1254 inline_constructor => 0,
1255 inline_accessors => 0,
1261 sub _remove_inlined_code {
1264 $self->remove_method( $_->name ) for $self->_inlined_methods;
1266 delete $self->{__immutable}{inlined_methods};
1269 sub _inlined_methods { @{ $_[0]{__immutable}{inlined_methods} || [] } }
1271 sub _add_inlined_method {
1272 my ( $self, $method ) = @_;
1274 push @{ $self->{__immutable}{inlined_methods} ||= [] }, $method;
1277 sub _initialize_immutable {
1278 my ( $self, %args ) = @_;
1280 $self->{__immutable}{options} = \%args;
1281 $self->_install_inlined_code(%args);
1284 sub _install_inlined_code {
1285 my ( $self, %args ) = @_;
1288 $self->_inline_accessors(%args) if $args{inline_accessors};
1289 $self->_inline_constructor(%args) if $args{inline_constructor};
1290 $self->_inline_destructor(%args) if $args{inline_destructor};
1293 sub _rebless_as_mutable {
1296 bless $self, $self->_get_mutable_metaclass_name;
1301 sub _inline_accessors {
1304 foreach my $attr_name ( $self->get_attribute_list ) {
1305 $self->get_attribute($attr_name)->install_accessors(1);
1309 sub _inline_constructor {
1310 my ( $self, %args ) = @_;
1312 my $name = $args{constructor_name};
1313 # A class may not even have a constructor, and that's okay.
1314 return unless defined $name;
1316 if ( $self->has_method($name) && !$args{replace_constructor} ) {
1317 my $class = $self->name;
1318 warn "Not inlining a constructor for $class since it defines"
1319 . " its own constructor.\n"
1320 . "If you are certain you don't need to inline your"
1321 . " constructor, specify inline_constructor => 0 in your"
1322 . " call to $class->meta->make_immutable\n";
1326 my $constructor_class = $args{constructor_class};
1328 Class::MOP::load_class($constructor_class);
1330 my $constructor = $constructor_class->new(
1334 package_name => $self->name,
1338 if ( $args{replace_constructor} or $constructor->can_be_inlined ) {
1339 $self->add_method( $name => $constructor );
1340 $self->_add_inlined_method($constructor);
1344 sub _inline_destructor {
1345 my ( $self, %args ) = @_;
1347 ( exists $args{destructor_class} && defined $args{destructor_class} )
1348 || confess "The 'inline_destructor' option is present, but "
1349 . "no destructor class was specified";
1351 if ( $self->has_method('DESTROY') && ! $args{replace_destructor} ) {
1352 my $class = $self->name;
1353 warn "Not inlining a destructor for $class since it defines"
1354 . " its own destructor.\n";
1358 my $destructor_class = $args{destructor_class};
1360 Class::MOP::load_class($destructor_class);
1362 return unless $destructor_class->is_needed($self);
1364 my $destructor = $destructor_class->new(
1367 package_name => $self->name,
1371 if ( $args{replace_destructor} or $destructor->can_be_inlined ) {
1372 $self->add_method( 'DESTROY' => $destructor );
1373 $self->_add_inlined_method($destructor);
1385 Class::MOP::Class - Class Meta Object
1389 # assuming that class Foo
1390 # has been defined, you can
1392 # use this for introspection ...
1394 # add a method to Foo ...
1395 Foo->meta->add_method( 'bar' => sub {...} )
1397 # get a list of all the classes searched
1398 # the method dispatcher in the correct order
1399 Foo->meta->class_precedence_list()
1401 # remove a method from Foo
1402 Foo->meta->remove_method('bar');
1404 # or use this to actually create classes ...
1406 Class::MOP::Class->create(
1409 superclasses => ['Foo'],
1411 Class::MOP::Attribute->new('$bar'),
1412 Class::MOP::Attribute->new('$baz'),
1415 calculate_bar => sub {...},
1416 construct_baz => sub {...}
1423 The Class Protocol is the largest and most complex part of the
1424 Class::MOP meta-object protocol. It controls the introspection and
1425 manipulation of Perl 5 classes, and it can create them as well. The
1426 best way to understand what this module can do is to read the
1427 documentation for each of its methods.
1431 C<Class::MOP::Class> is a subclass of L<Class::MOP::Module>.
1435 =head2 Class construction
1437 These methods all create new C<Class::MOP::Class> objects. These
1438 objects can represent existing classes or they can be used to create
1439 new classes from scratch.
1441 The metaclass object for a given class is a singleton. If you attempt
1442 to create a metaclass for the same class twice, you will just get the
1447 =item B<< Class::MOP::Class->create($package_name, %options) >>
1449 This method creates a new C<Class::MOP::Class> object with the given
1450 package name. It accepts a number of options:
1456 An optional version number for the newly created package.
1460 An optional authority for the newly created package.
1462 =item * superclasses
1464 An optional array reference of superclass names.
1468 An optional hash reference of methods for the class. The keys of the
1469 hash reference are method names and values are subroutine references.
1473 An optional array reference of L<Class::MOP::Attribute> objects.
1477 Specifies the name to install the C<meta> method for this class under.
1478 If it is not passed, C<meta> is assumed, and if C<undef> is explicitly
1479 given, no meta method will be installed.
1483 If true, the metaclass that is stored in the global cache will be a
1486 Classes created in this way are destroyed once the metaclass they are
1487 attached to goes out of scope, and will be removed from Perl's internal
1490 All instances of a class with a weakened metaclass keep a special
1491 reference to the metaclass object, which prevents the metaclass from
1492 going out of scope while any instances exist.
1494 This only works if the instance is based on a hash reference, however.
1498 =item B<< Class::MOP::Class->create_anon_class(%options) >>
1500 This method works just like C<< Class::MOP::Class->create >> but it
1501 creates an "anonymous" class. In fact, the class does have a name, but
1502 that name is a unique name generated internally by this module.
1504 It accepts the same C<superclasses>, C<methods>, and C<attributes>
1505 parameters that C<create> accepts.
1507 Anonymous classes default to C<< weaken => 1 >>, although this can be
1510 =item B<< Class::MOP::Class->initialize($package_name, %options) >>
1512 This method will initialize a C<Class::MOP::Class> object for the
1513 named package. Unlike C<create>, this method I<will not> create a new
1516 The purpose of this method is to retrieve a C<Class::MOP::Class>
1517 object for introspecting an existing class.
1519 If an existing C<Class::MOP::Class> object exists for the named
1520 package, it will be returned, and any options provided will be
1523 If the object does not yet exist, it will be created.
1525 The valid options that can be passed to this method are
1526 C<attribute_metaclass>, C<method_metaclass>,
1527 C<wrapped_method_metaclass>, and C<instance_metaclass>. These are all
1528 optional, and default to the appropriate class in the C<Class::MOP>
1533 =head2 Object instance construction and cloning
1535 These methods are all related to creating and/or cloning object
1540 =item B<< $metaclass->clone_object($instance, %params) >>
1542 This method clones an existing object instance. Any parameters you
1543 provide are will override existing attribute values in the object.
1545 This is a convenience method for cloning an object instance, then
1546 blessing it into the appropriate package.
1548 You could implement a clone method in your class, using this method:
1551 my ($self, %params) = @_;
1552 $self->meta->clone_object($self, %params);
1555 =item B<< $metaclass->rebless_instance($instance, %params) >>
1557 This method changes the class of C<$instance> to the metaclass's class.
1559 You can only rebless an instance into a subclass of its current
1560 class. If you pass any additional parameters, these will be treated
1561 like constructor parameters and used to initialize the object's
1562 attributes. Any existing attributes that are already set will be
1565 Before reblessing the instance, this method will call
1566 C<rebless_instance_away> on the instance's current metaclass. This method
1567 will be passed the instance, the new metaclass, and any parameters
1568 specified to C<rebless_instance>. By default, C<rebless_instance_away>
1569 does nothing; it is merely a hook.
1571 =item B<< $metaclass->rebless_instance_back($instance) >>
1573 Does the same thing as C<rebless_instance>, except that you can only
1574 rebless an instance into one of its superclasses. Any attributes that
1575 do not exist in the superclass will be deinitialized.
1577 This is a much more dangerous operation than C<rebless_instance>,
1578 especially when multiple inheritance is involved, so use this carefully!
1580 =item B<< $metaclass->new_object(%params) >>
1582 This method is used to create a new object of the metaclass's
1583 class. Any parameters you provide are used to initialize the
1584 instance's attributes. A special C<__INSTANCE__> key can be passed to
1585 provide an already generated instance, rather than having Class::MOP
1586 generate it for you. This is mostly useful for using Class::MOP with
1587 foreign classes which generate instances using their own constructors.
1589 =item B<< $metaclass->instance_metaclass >>
1591 Returns the class name of the instance metaclass. See
1592 L<Class::MOP::Instance> for more information on the instance
1595 =item B<< $metaclass->get_meta_instance >>
1597 Returns an instance of the C<instance_metaclass> to be used in the
1598 construction of a new instance of the class.
1600 =item B<< $metaclass->inline_create_instance($class_var) >>
1602 =item B<< $metaclass->inline_rebless_instance($instance_var, $class_var) >>
1604 These methods takes variable names, and use them to create an inline snippet
1605 of code that will create a new instance of the class.
1609 =head2 Informational predicates
1611 These are a few predicate methods for asking information about the
1616 =item B<< $metaclass->is_anon_class >>
1618 This returns true if the class was created by calling C<<
1619 Class::MOP::Class->create_anon_class >>.
1621 =item B<< $metaclass->is_mutable >>
1623 This returns true if the class is still mutable.
1625 =item B<< $metaclass->is_immutable >>
1627 This returns true if the class has been made immutable.
1629 =item B<< $metaclass->is_pristine >>
1631 A class is I<not> pristine if it has non-inherited attributes or if it
1632 has any generated methods.
1636 =head2 Inheritance Relationships
1640 =item B<< $metaclass->superclasses(@superclasses) >>
1642 This is a read-write accessor which represents the superclass
1643 relationships of the metaclass's class.
1645 This is basically sugar around getting and setting C<@ISA>.
1647 =item B<< $metaclass->class_precedence_list >>
1649 This returns a list of all of the class's ancestor classes. The
1650 classes are returned in method dispatch order.
1652 =item B<< $metaclass->linearized_isa >>
1654 This returns a list based on C<class_precedence_list> but with all
1657 =item B<< $metaclass->subclasses >>
1659 This returns a list of all subclasses for this class, even indirect
1662 =item B<< $metaclass->direct_subclasses >>
1664 This returns a list of immediate subclasses for this class, which does not
1665 include indirect subclasses.
1669 =head2 Method introspection and creation
1671 These methods allow you to introspect a class's methods, as well as
1672 add, remove, or change methods.
1674 Determining what is truly a method in a Perl 5 class requires some
1675 heuristics (aka guessing).
1677 Methods defined outside the package with a fully qualified name (C<sub
1678 Package::name { ... }>) will be included. Similarly, methods named
1679 with a fully qualified name using L<Sub::Name> are also included.
1681 However, we attempt to ignore imported functions.
1683 Ultimately, we are using heuristics to determine what truly is a
1684 method in a class, and these heuristics may get the wrong answer in
1685 some edge cases. However, for most "normal" cases the heuristics work
1690 =item B<< $metaclass->get_method($method_name) >>
1692 This will return a L<Class::MOP::Method> for the specified
1693 C<$method_name>. If the class does not have the specified method, it
1696 =item B<< $metaclass->has_method($method_name) >>
1698 Returns a boolean indicating whether or not the class defines the
1699 named method. It does not include methods inherited from parent
1702 =item B<< $metaclass->get_method_list >>
1704 This will return a list of method I<names> for all methods defined in
1707 =item B<< $metaclass->add_method($method_name, $method) >>
1709 This method takes a method name and a subroutine reference, and adds
1710 the method to the class.
1712 The subroutine reference can be a L<Class::MOP::Method>, and you are
1713 strongly encouraged to pass a meta method object instead of a code
1714 reference. If you do so, that object gets stored as part of the
1715 class's method map directly. If not, the meta information will have to
1716 be recreated later, and may be incorrect.
1718 If you provide a method object, this method will clone that object if
1719 the object's package name does not match the class name. This lets us
1720 track the original source of any methods added from other classes
1721 (notably Moose roles).
1723 =item B<< $metaclass->remove_method($method_name) >>
1725 Remove the named method from the class. This method returns the
1726 L<Class::MOP::Method> object for the method.
1728 =item B<< $metaclass->method_metaclass >>
1730 Returns the class name of the method metaclass, see
1731 L<Class::MOP::Method> for more information on the method metaclass.
1733 =item B<< $metaclass->wrapped_method_metaclass >>
1735 Returns the class name of the wrapped method metaclass, see
1736 L<Class::MOP::Method::Wrapped> for more information on the wrapped
1739 =item B<< $metaclass->get_all_methods >>
1741 This will traverse the inheritance hierarchy and return a list of all
1742 the L<Class::MOP::Method> objects for this class and its parents.
1744 =item B<< $metaclass->find_method_by_name($method_name) >>
1746 This will return a L<Class::MOP::Method> for the specified
1747 C<$method_name>. If the class does not have the specified method, it
1750 Unlike C<get_method>, this method I<will> look for the named method in
1753 =item B<< $metaclass->get_all_method_names >>
1755 This will return a list of method I<names> for all of this class's
1756 methods, including inherited methods.
1758 =item B<< $metaclass->find_all_methods_by_name($method_name) >>
1760 This method looks for the named method in the class and all of its
1761 parents. It returns every matching method it finds in the inheritance
1762 tree, so it returns a list of methods.
1764 Each method is returned as a hash reference with three keys. The keys
1765 are C<name>, C<class>, and C<code>. The C<code> key has a
1766 L<Class::MOP::Method> object as its value.
1768 The list of methods is distinct.
1770 =item B<< $metaclass->find_next_method_by_name($method_name) >>
1772 This method returns the first method in any superclass matching the
1773 given name. It is effectively the method that C<SUPER::$method_name>
1778 =head2 Attribute introspection and creation
1780 Because Perl 5 does not have a core concept of attributes in classes,
1781 we can only return information about attributes which have been added
1782 via this class's methods. We cannot discover information about
1783 attributes which are defined in terms of "regular" Perl 5 methods.
1787 =item B<< $metaclass->get_attribute($attribute_name) >>
1789 This will return a L<Class::MOP::Attribute> for the specified
1790 C<$attribute_name>. If the class does not have the specified
1791 attribute, it returns C<undef>.
1793 NOTE that get_attribute does not search superclasses, for that you
1794 need to use C<find_attribute_by_name>.
1796 =item B<< $metaclass->has_attribute($attribute_name) >>
1798 Returns a boolean indicating whether or not the class defines the
1799 named attribute. It does not include attributes inherited from parent
1802 =item B<< $metaclass->get_attribute_list >>
1804 This will return a list of attributes I<names> for all attributes
1805 defined in this class. Note that this operates on the current class
1806 only, it does not traverse the inheritance hierarchy.
1808 =item B<< $metaclass->get_all_attributes >>
1810 This will traverse the inheritance hierarchy and return a list of all
1811 the L<Class::MOP::Attribute> objects for this class and its parents.
1813 =item B<< $metaclass->find_attribute_by_name($attribute_name) >>
1815 This will return a L<Class::MOP::Attribute> for the specified
1816 C<$attribute_name>. If the class does not have the specified
1817 attribute, it returns C<undef>.
1819 Unlike C<get_attribute>, this attribute I<will> look for the named
1820 attribute in superclasses.
1822 =item B<< $metaclass->add_attribute(...) >>
1824 This method accepts either an existing L<Class::MOP::Attribute>
1825 object or parameters suitable for passing to that class's C<new>
1828 The attribute provided will be added to the class.
1830 Any accessor methods defined by the attribute will be added to the
1831 class when the attribute is added.
1833 If an attribute of the same name already exists, the old attribute
1834 will be removed first.
1836 =item B<< $metaclass->remove_attribute($attribute_name) >>
1838 This will remove the named attribute from the class, and
1839 L<Class::MOP::Attribute> object.
1841 Removing an attribute also removes any accessor methods defined by the
1844 However, note that removing an attribute will only affect I<future>
1845 object instances created for this class, not existing instances.
1847 =item B<< $metaclass->attribute_metaclass >>
1849 Returns the class name of the attribute metaclass for this class. By
1850 default, this is L<Class::MOP::Attribute>.
1854 =head2 Class Immutability
1856 Making a class immutable "freezes" the class definition. You can no
1857 longer call methods which alter the class, such as adding or removing
1858 methods or attributes.
1860 Making a class immutable lets us optimize the class by inlining some
1861 methods, and also allows us to optimize some methods on the metaclass
1864 After immutabilization, the metaclass object will cache most informational
1865 methods that returns information about methods or attributes. Methods which
1866 would alter the class, such as C<add_attribute> and C<add_method>, will
1867 throw an error on an immutable metaclass object.
1869 The immutabilization system in L<Moose> takes much greater advantage
1870 of the inlining features than Class::MOP itself does.
1874 =item B<< $metaclass->make_immutable(%options) >>
1876 This method will create an immutable transformer and use it to make
1877 the class and its metaclass object immutable.
1879 This method accepts the following options:
1883 =item * inline_accessors
1885 =item * inline_constructor
1887 =item * inline_destructor
1889 These are all booleans indicating whether the specified method(s)
1892 By default, accessors and the constructor are inlined, but not the
1895 =item * immutable_trait
1897 The name of a class which will be used as a parent class for the
1898 metaclass object being made immutable. This "trait" implements the
1899 post-immutability functionality of the metaclass (but not the
1900 transformation itself).
1902 This defaults to L<Class::MOP::Class::Immutable::Trait>.
1904 =item * constructor_name
1906 This is the constructor method name. This defaults to "new".
1908 =item * constructor_class
1910 The name of the method metaclass for constructors. It will be used to
1911 generate the inlined constructor. This defaults to
1912 "Class::MOP::Method::Constructor".
1914 =item * replace_constructor
1916 This is a boolean indicating whether an existing constructor should be
1917 replaced when inlining a constructor. This defaults to false.
1919 =item * destructor_class
1921 The name of the method metaclass for destructors. It will be used to
1922 generate the inlined destructor. This defaults to
1923 "Class::MOP::Method::Denstructor".
1925 =item * replace_destructor
1927 This is a boolean indicating whether an existing destructor should be
1928 replaced when inlining a destructor. This defaults to false.
1932 =item B<< $metaclass->immutable_options >>
1934 Returns a hash of the options used when making the class immutable, including
1935 both defaults and anything supplied by the user in the call to C<<
1936 $metaclass->make_immutable >>. This is useful if you need to temporarily make
1937 a class mutable and then restore immutability as it was before.
1939 =item B<< $metaclass->make_mutable >>
1941 Calling this method reverse the immutabilization transformation.
1945 =head2 Method Modifiers
1947 Method modifiers are hooks which allow a method to be wrapped with
1948 I<before>, I<after> and I<around> method modifiers. Every time a
1949 method is called, its modifiers are also called.
1951 A class can modify its own methods, as well as methods defined in
1954 =head3 How method modifiers work?
1956 Method modifiers work by wrapping the original method and then
1957 replacing it in the class's symbol table. The wrappers will handle
1958 calling all the modifiers in the appropriate order and preserving the
1959 calling context for the original method.
1961 The return values of C<before> and C<after> modifiers are
1962 ignored. This is because their purpose is B<not> to filter the input
1963 and output of the primary method (this is done with an I<around>
1966 This may seem like an odd restriction to some, but doing this allows
1967 for simple code to be added at the beginning or end of a method call
1968 without altering the function of the wrapped method or placing any
1969 extra responsibility on the code of the modifier.
1971 Of course if you have more complex needs, you can use the C<around>
1972 modifier which allows you to change both the parameters passed to the
1973 wrapped method, as well as its return value.
1975 Before and around modifiers are called in last-defined-first-called
1976 order, while after modifiers are called in first-defined-first-called
1977 order. So the call tree might looks something like this:
1989 =head3 What is the performance impact?
1991 Of course there is a performance cost associated with method
1992 modifiers, but we have made every effort to make that cost directly
1993 proportional to the number of modifier features you use.
1995 The wrapping method does its best to B<only> do as much work as it
1996 absolutely needs to. In order to do this we have moved some of the
1997 performance costs to set-up time, where they are easier to amortize.
1999 All this said, our benchmarks have indicated the following:
2001 simple wrapper with no modifiers 100% slower
2002 simple wrapper with simple before modifier 400% slower
2003 simple wrapper with simple after modifier 450% slower
2004 simple wrapper with simple around modifier 500-550% slower
2005 simple wrapper with all 3 modifiers 1100% slower
2007 These numbers may seem daunting, but you must remember, every feature
2008 comes with some cost. To put things in perspective, just doing a
2009 simple C<AUTOLOAD> which does nothing but extract the name of the
2010 method called and return it costs about 400% over a normal method
2015 =item B<< $metaclass->add_before_method_modifier($method_name, $code) >>
2017 This wraps the specified method with the supplied subroutine
2018 reference. The modifier will be called as a method itself, and will
2019 receive the same arguments as are passed to the method.
2021 When the modifier exits, the wrapped method will be called.
2023 The return value of the modifier will be ignored.
2025 =item B<< $metaclass->add_after_method_modifier($method_name, $code) >>
2027 This wraps the specified method with the supplied subroutine
2028 reference. The modifier will be called as a method itself, and will
2029 receive the same arguments as are passed to the method.
2031 When the wrapped methods exits, the modifier will be called.
2033 The return value of the modifier will be ignored.
2035 =item B<< $metaclass->add_around_method_modifier($method_name, $code) >>
2037 This wraps the specified method with the supplied subroutine
2040 The first argument passed to the modifier will be a subroutine
2041 reference to the wrapped method. The second argument is the object,
2042 and after that come any arguments passed when the method is called.
2044 The around modifier can choose to call the original method, as well as
2045 what arguments to pass if it does so.
2047 The return value of the modifier is what will be seen by the caller.
2051 =head2 Introspection
2055 =item B<< Class::MOP::Class->meta >>
2057 This will return a L<Class::MOP::Class> instance for this class.
2059 It should also be noted that L<Class::MOP> will actually bootstrap
2060 this module by installing a number of attribute meta-objects into its
2067 Stevan Little E<lt>stevan@iinteractive.comE<gt>
2069 =head1 COPYRIGHT AND LICENSE
2071 Copyright 2006-2010 by Infinity Interactive, Inc.
2073 L<http://www.iinteractive.com>
2075 This library is free software; you can redistribute it and/or modify
2076 it under the same terms as Perl itself.