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;
13 use Scalar::Util 'blessed', 'reftype';
14 use Sub::Name 'subname';
15 use Devel::GlobalDestruction 'in_global_destruction';
17 our $VERSION = '0.92';
18 $VERSION = eval $VERSION;
19 our $AUTHORITY = 'cpan:STEVAN';
21 use base 'Class::MOP::Module';
31 $package_name = shift;
34 $package_name = $options{package};
37 ($package_name && !ref($package_name))
38 || confess "You must pass a package name and it cannot be blessed";
40 return Class::MOP::get_metaclass_by_name($package_name)
41 || $class->_construct_class_instance(package => $package_name, @_);
44 # NOTE: (meta-circularity)
45 # this is a special form of _construct_instance
46 # (see below), which is used to construct class
47 # meta-object instances for any Class::MOP::*
48 # class. All other classes will use the more
49 # normal &construct_instance.
50 sub _construct_class_instance {
52 my $options = @_ == 1 ? $_[0] : {@_};
53 my $package_name = $options->{package};
54 (defined $package_name && $package_name)
55 || confess "You must pass a package name";
57 # return the metaclass if we have it cached,
58 # and it is still defined (it has not been
59 # reaped by DESTROY yet, which can happen
60 # annoyingly enough during global destruction)
62 if (defined(my $meta = Class::MOP::get_metaclass_by_name($package_name))) {
67 # we need to deal with the possibility
68 # of class immutability here, and then
69 # get the name of the class appropriately
71 ? ($class->is_immutable
72 ? $class->get_mutable_metaclass_name()
76 # now create the metaclass
78 if ($class eq 'Class::MOP::Class') {
79 $meta = $class->_new($options);
83 # it is safe to use meta here because
84 # class will always be a subclass of
85 # Class::MOP::Class, which defines meta
86 $meta = $class->meta->_construct_instance($options)
89 # and check the metaclass compatibility
90 $meta->_check_metaclass_compatibility();
92 Class::MOP::store_metaclass_by_name($package_name, $meta);
95 # we need to weaken any anon classes
96 # so that they can call DESTROY properly
97 Class::MOP::weaken_metaclass($package_name) if $meta->is_anon_class;
105 return Class::MOP::Class->initialize($class)->new_object(@_)
106 if $class ne __PACKAGE__;
108 my $options = @_ == 1 ? $_[0] : {@_};
111 # inherited from Class::MOP::Package
112 'package' => $options->{package},
115 # since the following attributes will
116 # actually be loaded from the symbol
117 # table, and actually bypass the instance
118 # entirely, we can just leave these things
119 # listed here for reference, because they
120 # should not actually have a value associated
122 'namespace' => \undef,
124 # inherited from Class::MOP::Module
126 'authority' => \undef,
128 # defined in Class::MOP::Class
129 'superclasses' => \undef,
133 'attribute_metaclass' =>
134 ( $options->{'attribute_metaclass'} || 'Class::MOP::Attribute' ),
135 'method_metaclass' =>
136 ( $options->{'method_metaclass'} || 'Class::MOP::Method' ),
137 'wrapped_method_metaclass' => (
138 $options->{'wrapped_method_metaclass'}
139 || 'Class::MOP::Method::Wrapped'
141 'instance_metaclass' =>
142 ( $options->{'instance_metaclass'} || 'Class::MOP::Instance' ),
143 'immutable_trait' => (
144 $options->{'immutable_trait'}
145 || 'Class::MOP::Class::Immutable::Trait'
147 'constructor_name' => ( $options->{constructor_name} || 'new' ),
148 'constructor_class' => (
149 $options->{constructor_class} || 'Class::MOP::Method::Constructor'
151 'destructor_class' => $options->{destructor_class},
155 sub reset_package_cache_flag { (shift)->{'_package_cache_flag'} = undef }
156 sub update_package_cache_flag {
159 # we can manually update the cache number
160 # since we are actually adding the method
161 # to our cache as well. This avoids us
162 # having to regenerate the method_map.
164 $self->{'_package_cache_flag'} = Class::MOP::check_package_cache_flag($self->name);
167 sub _check_metaclass_compatibility {
170 # this is always okay ...
171 return if ref($self) eq 'Class::MOP::Class' &&
172 $self->instance_metaclass eq 'Class::MOP::Instance';
174 my @class_list = $self->linearized_isa;
175 shift @class_list; # shift off $self->name
177 foreach my $superclass_name (@class_list) {
178 my $super_meta = Class::MOP::get_metaclass_by_name($superclass_name) || next;
181 # we need to deal with the possibility
182 # of class immutability here, and then
183 # get the name of the class appropriately
185 = $super_meta->is_immutable
186 ? $super_meta->get_mutable_metaclass_name()
189 ($self->isa($super_meta_type))
190 || confess "The metaclass of " . $self->name . " ("
191 . (ref($self)) . ")" . " is not compatible with the " .
192 "metaclass of its superclass, ".$superclass_name . " ("
193 . ($super_meta_type) . ")";
195 # we also need to check that instance metaclasses
196 # are compatibile in the same the class.
197 ($self->instance_metaclass->isa($super_meta->instance_metaclass))
198 || confess "The instance metaclass for " . $self->name . " (" . ($self->instance_metaclass) . ")" .
199 " is not compatible with the " .
200 "instance metaclass of its superclass, " . $superclass_name . " (" . ($super_meta->instance_metaclass) . ")";
208 # this should be sufficient, if you have a
209 # use case where it is not, write a test and
211 my $ANON_CLASS_SERIAL = 0;
214 # we need a sufficiently annoying prefix
215 # this should suffice for now, this is
216 # used in a couple of places below, so
217 # need to put it up here for now.
218 my $ANON_CLASS_PREFIX = 'Class::MOP::Class::__ANON__::SERIAL::';
222 no warnings 'uninitialized';
223 $self->name =~ /^$ANON_CLASS_PREFIX/o;
226 sub create_anon_class {
227 my ($class, %options) = @_;
228 my $package_name = $ANON_CLASS_PREFIX . ++$ANON_CLASS_SERIAL;
229 return $class->create($package_name, %options);
233 # this will only get called for
234 # anon-classes, all other calls
235 # are assumed to occur during
236 # global destruction and so don't
237 # really need to be handled explicitly
241 return if in_global_destruction(); # it'll happen soon anyway and this just makes things more complicated
243 no warnings 'uninitialized';
244 my $name = $self->name;
245 return unless $name =~ /^$ANON_CLASS_PREFIX/o;
246 # Moose does a weird thing where it replaces the metaclass for
247 # class when fixing metaclass incompatibility. In that case,
248 # we don't want to clean out the namespace now. We can detect
249 # that because Moose will explicitly update the singleton
250 # cache in Class::MOP.
251 my $current_meta = Class::MOP::get_metaclass_by_name($name);
252 return if $current_meta ne $self;
254 my ($serial_id) = ($name =~ /^$ANON_CLASS_PREFIX(\d+)/o);
256 @{$name . '::ISA'} = ();
257 %{$name . '::'} = ();
258 delete ${$ANON_CLASS_PREFIX}{$serial_id . '::'};
260 Class::MOP::remove_metaclass_by_name($name);
265 # creating classes with MOP ...
268 my ( $class, @args ) = @_;
270 unshift @args, 'package' if @args % 2 == 1;
272 my (%options) = @args;
273 my $package_name = $options{package};
275 (ref $options{superclasses} eq 'ARRAY')
276 || confess "You must pass an ARRAY ref of superclasses"
277 if exists $options{superclasses};
279 (ref $options{attributes} eq 'ARRAY')
280 || confess "You must pass an ARRAY ref of attributes"
281 if exists $options{attributes};
283 (ref $options{methods} eq 'HASH')
284 || confess "You must pass a HASH ref of methods"
285 if exists $options{methods};
287 my (%initialize_options) = @args;
288 delete @initialize_options{qw(
296 my $meta = $class->initialize( $package_name => %initialize_options );
298 $meta->_instantiate_module( $options{version}, $options{authority} );
301 $meta->add_method('meta' => sub {
302 $class->initialize(ref($_[0]) || $_[0]);
305 $meta->superclasses(@{$options{superclasses}})
306 if exists $options{superclasses};
308 # process attributes first, so that they can
309 # install accessors, but locally defined methods
310 # can then overwrite them. It is maybe a little odd, but
311 # I think this should be the order of things.
312 if (exists $options{attributes}) {
313 foreach my $attr (@{$options{attributes}}) {
314 $meta->add_attribute($attr);
317 if (exists $options{methods}) {
318 foreach my $method_name (keys %{$options{methods}}) {
319 $meta->add_method($method_name, $options{methods}->{$method_name});
326 # Instance Construction & Cloning
332 # we need to protect the integrity of the
333 # Class::MOP::Class singletons here, so we
334 # delegate this to &construct_class_instance
335 # which will deal with the singletons
336 return $class->_construct_class_instance(@_)
337 if $class->name->isa('Class::MOP::Class');
338 return $class->_construct_instance(@_);
341 sub _construct_instance {
343 my $params = @_ == 1 ? $_[0] : {@_};
344 my $meta_instance = $class->get_meta_instance();
346 # the code below is almost certainly incorrect
347 # but this is foreign inheritance, so we might
348 # have to kludge it in the end.
349 my $instance = $params->{__INSTANCE__} || $meta_instance->create_instance();
350 foreach my $attr ($class->get_all_attributes()) {
351 $attr->initialize_instance_slot($meta_instance, $instance, $params);
354 # this will only work for a HASH instance type
355 if ($class->is_anon_class) {
356 (reftype($instance) eq 'HASH')
357 || confess "Currently only HASH based instances are supported with instance of anon-classes";
359 # At some point we should make this official
360 # as a reserved slot name, but right now I am
361 # going to keep it here.
362 # my $RESERVED_MOP_SLOT = '__MOP__';
363 $instance->{'__MOP__'} = $class;
369 sub get_meta_instance {
371 $self->{'_meta_instance'} ||= $self->_create_meta_instance();
374 sub _create_meta_instance {
377 my $instance = $self->instance_metaclass->new(
378 associated_metaclass => $self,
379 attributes => [ $self->get_all_attributes() ],
382 $self->add_meta_instance_dependencies()
383 if $instance->is_dependent_on_superclasses();
390 my $instance = shift;
391 (blessed($instance) && $instance->isa($class->name))
392 || confess "You must pass an instance of the metaclass (" . (ref $class ? $class->name : $class) . "), not ($instance)";
395 # we need to protect the integrity of the
396 # Class::MOP::Class singletons here, they
397 # should not be cloned.
398 return $instance if $instance->isa('Class::MOP::Class');
399 $class->_clone_instance($instance, @_);
402 sub _clone_instance {
403 my ($class, $instance, %params) = @_;
405 || confess "You can only clone instances, ($instance) is not a blessed instance";
406 my $meta_instance = $class->get_meta_instance();
407 my $clone = $meta_instance->clone_instance($instance);
408 foreach my $attr ($class->get_all_attributes()) {
409 if ( defined( my $init_arg = $attr->init_arg ) ) {
410 if (exists $params{$init_arg}) {
411 $attr->set_value($clone, $params{$init_arg});
418 sub rebless_instance {
419 my ($self, $instance, %params) = @_;
421 my $old_metaclass = Class::MOP::class_of($instance);
423 my $old_class = $old_metaclass ? $old_metaclass->name : blessed($instance);
424 $self->name->isa($old_class)
425 || confess "You may rebless only into a subclass of ($old_class), of which (". $self->name .") isn't.";
427 $old_metaclass->rebless_instance_away($instance, $self, %params)
430 my $meta_instance = $self->get_meta_instance();
433 # we use $_[1] here because of t/306_rebless_overload.t regressions on 5.8.8
434 $meta_instance->rebless_instance_structure($_[1], $self);
436 foreach my $attr ( $self->get_all_attributes ) {
437 if ( $attr->has_value($instance) ) {
438 if ( defined( my $init_arg = $attr->init_arg ) ) {
439 $params{$init_arg} = $attr->get_value($instance)
440 unless exists $params{$init_arg};
443 $attr->set_value($instance, $attr->get_value($instance));
448 foreach my $attr ($self->get_all_attributes) {
449 $attr->initialize_instance_slot($meta_instance, $instance, \%params);
455 sub rebless_instance_away {
456 # this intentionally does nothing, it is just a hook
463 my $var_spec = { sigil => '@', type => 'ARRAY', name => 'ISA' };
466 @{$self->get_package_symbol($var_spec)} = @supers;
469 # on 5.8 and below, we need to call
470 # a method to get Perl to detect
471 # a cycle in the class hierarchy
472 my $class = $self->name;
476 # we need to check the metaclass
477 # compatibility here so that we can
478 # be sure that the superclass is
479 # not potentially creating an issues
480 # we don't know about
482 $self->_check_metaclass_compatibility();
483 $self->_superclasses_updated();
485 @{$self->get_package_symbol($var_spec)};
488 sub _superclasses_updated {
490 $self->update_meta_instance_dependencies();
495 my $super_class = $self->name;
497 return @{ $super_class->mro::get_isarev() };
500 sub direct_subclasses {
502 my $super_class = $self->name;
507 } Class::MOP::Class->initialize($_)->superclasses
512 return @{ mro::get_linear_isa( (shift)->name ) };
515 sub class_precedence_list {
517 my $name = $self->name;
519 unless (Class::MOP::IS_RUNNING_ON_5_10()) {
521 # We need to check for circular inheritance here
522 # if we are are not on 5.10, cause 5.8 detects it
523 # late. This will do nothing if all is well, and
524 # blow up otherwise. Yes, it's an ugly hack, better
525 # suggestions are welcome.
527 ($name || return)->isa('This is a test for circular inheritance')
530 # if our mro is c3, we can
531 # just grab the linear_isa
532 if (mro::get_mro($name) eq 'c3') {
533 return @{ mro::get_linear_isa($name) }
537 # we can't grab the linear_isa for dfs
538 # since it has all the duplicates
543 $self->initialize($_)->class_precedence_list()
544 } $self->superclasses()
552 my $fetch_and_prepare_method = sub {
553 my ($self, $method_name) = @_;
554 my $wrapped_metaclass = $self->wrapped_method_metaclass;
556 my $method = $self->get_method($method_name);
557 # if we dont have local ...
559 # try to find the next method
560 $method = $self->find_next_method_by_name($method_name);
561 # die if it does not exist
563 || confess "The method '$method_name' was not found in the inheritance hierarchy for " . $self->name;
564 # and now make sure to wrap it
565 # even if it is already wrapped
566 # because we need a new sub ref
567 $method = $wrapped_metaclass->wrap($method,
568 package_name => $self->name,
569 name => $method_name,
573 # now make sure we wrap it properly
574 $method = $wrapped_metaclass->wrap($method,
575 package_name => $self->name,
576 name => $method_name,
577 ) unless $method->isa($wrapped_metaclass);
579 $self->add_method($method_name => $method);
583 sub add_before_method_modifier {
584 my ($self, $method_name, $method_modifier) = @_;
585 (defined $method_name && $method_name)
586 || confess "You must pass in a method name";
587 my $method = $fetch_and_prepare_method->($self, $method_name);
588 $method->add_before_modifier(
589 subname(':before' => $method_modifier)
593 sub add_after_method_modifier {
594 my ($self, $method_name, $method_modifier) = @_;
595 (defined $method_name && $method_name)
596 || confess "You must pass in a method name";
597 my $method = $fetch_and_prepare_method->($self, $method_name);
598 $method->add_after_modifier(
599 subname(':after' => $method_modifier)
603 sub add_around_method_modifier {
604 my ($self, $method_name, $method_modifier) = @_;
605 (defined $method_name && $method_name)
606 || confess "You must pass in a method name";
607 my $method = $fetch_and_prepare_method->($self, $method_name);
608 $method->add_around_modifier(
609 subname(':around' => $method_modifier)
614 # the methods above used to be named like this:
615 # ${pkg}::${method}:(before|after|around)
616 # but this proved problematic when using one modifier
617 # to wrap multiple methods (something which is likely
618 # to happen pretty regularly IMO). So instead of naming
619 # it like this, I have chosen to just name them purely
620 # with their modifier names, like so:
621 # :(before|after|around)
622 # The fact is that in a stack trace, it will be fairly
623 # evident from the context what method they are attached
624 # to, and so don't need the fully qualified name.
627 sub find_method_by_name {
628 my ($self, $method_name) = @_;
629 (defined $method_name && $method_name)
630 || confess "You must define a method name to find";
631 foreach my $class ($self->linearized_isa) {
632 my $method = $self->initialize($class)->get_method($method_name);
633 return $method if defined $method;
638 sub get_all_methods {
640 my %methods = map { %{ $self->initialize($_)->get_method_map } } reverse $self->linearized_isa;
641 return values %methods;
644 sub get_all_method_names {
647 return grep { !$uniq{$_}++ } map { $self->initialize($_)->get_method_list } $self->linearized_isa;
650 sub find_all_methods_by_name {
651 my ($self, $method_name) = @_;
652 (defined $method_name && $method_name)
653 || confess "You must define a method name to find";
655 foreach my $class ($self->linearized_isa) {
656 # fetch the meta-class ...
657 my $meta = $self->initialize($class);
659 name => $method_name,
661 code => $meta->get_method($method_name)
662 } if $meta->has_method($method_name);
667 sub find_next_method_by_name {
668 my ($self, $method_name) = @_;
669 (defined $method_name && $method_name)
670 || confess "You must define a method name to find";
671 my @cpl = $self->linearized_isa;
672 shift @cpl; # discard ourselves
673 foreach my $class (@cpl) {
674 my $method = $self->initialize($class)->get_method($method_name);
675 return $method if defined $method;
684 # either we have an attribute object already
685 # or we need to create one from the args provided
686 my $attribute = blessed($_[0]) ? $_[0] : $self->attribute_metaclass->new(@_);
687 # make sure it is derived from the correct type though
688 ($attribute->isa('Class::MOP::Attribute'))
689 || confess "Your attribute must be an instance of Class::MOP::Attribute (or a subclass)";
691 # first we attach our new attribute
692 # because it might need certain information
693 # about the class which it is attached to
694 $attribute->attach_to_class($self);
696 my $attr_name = $attribute->name;
698 # then we remove attributes of a conflicting
699 # name here so that we can properly detach
700 # the old attr object, and remove any
701 # accessors it would have generated
702 if ( $self->has_attribute($attr_name) ) {
703 $self->remove_attribute($attr_name);
705 $self->invalidate_meta_instances();
708 # get our count of previously inserted attributes and
709 # increment by one so this attribute knows its order
710 my $order = (scalar keys %{$self->get_attribute_map});
711 $attribute->_set_insertion_order($order);
713 # then onto installing the new accessors
714 $self->get_attribute_map->{$attr_name} = $attribute;
716 # invalidate package flag here
720 eval { $attribute->install_accessors() };
724 $self->remove_attribute($attr_name);
731 sub update_meta_instance_dependencies {
734 if ( $self->{meta_instance_dependencies} ) {
735 return $self->add_meta_instance_dependencies;
739 sub add_meta_instance_dependencies {
742 $self->remove_meta_instance_dependencies;
744 my @attrs = $self->get_all_attributes();
747 my @classes = grep { not $seen{$_->name}++ } map { $_->associated_class } @attrs;
749 foreach my $class ( @classes ) {
750 $class->add_dependent_meta_instance($self);
753 $self->{meta_instance_dependencies} = \@classes;
756 sub remove_meta_instance_dependencies {
759 if ( my $classes = delete $self->{meta_instance_dependencies} ) {
760 foreach my $class ( @$classes ) {
761 $class->remove_dependent_meta_instance($self);
771 sub add_dependent_meta_instance {
772 my ( $self, $metaclass ) = @_;
773 push @{ $self->{dependent_meta_instances} }, $metaclass;
776 sub remove_dependent_meta_instance {
777 my ( $self, $metaclass ) = @_;
778 my $name = $metaclass->name;
779 @$_ = grep { $_->name ne $name } @$_ for $self->{dependent_meta_instances};
782 sub invalidate_meta_instances {
784 $_->invalidate_meta_instance() for $self, @{ $self->{dependent_meta_instances} };
787 sub invalidate_meta_instance {
789 undef $self->{_meta_instance};
793 my ($self, $attribute_name) = @_;
794 (defined $attribute_name)
795 || confess "You must define an attribute name";
796 exists $self->get_attribute_map->{$attribute_name};
800 my ($self, $attribute_name) = @_;
801 (defined $attribute_name)
802 || confess "You must define an attribute name";
803 return $self->get_attribute_map->{$attribute_name}
805 # this will return undef anyway, so no need ...
806 # if $self->has_attribute($attribute_name);
810 sub remove_attribute {
811 my ($self, $attribute_name) = @_;
812 (defined $attribute_name)
813 || confess "You must define an attribute name";
814 my $removed_attribute = $self->get_attribute_map->{$attribute_name};
815 return unless defined $removed_attribute;
816 delete $self->get_attribute_map->{$attribute_name};
817 $self->invalidate_meta_instances();
818 $removed_attribute->remove_accessors();
819 $removed_attribute->detach_from_class();
820 return $removed_attribute;
823 sub get_attribute_list {
825 keys %{$self->get_attribute_map};
828 sub get_all_attributes {
830 my %attrs = map { %{ $self->initialize($_)->get_attribute_map } } reverse $self->linearized_isa;
831 return values %attrs;
834 sub find_attribute_by_name {
835 my ($self, $attr_name) = @_;
836 foreach my $class ($self->linearized_isa) {
837 # fetch the meta-class ...
838 my $meta = $self->initialize($class);
839 return $meta->get_attribute($attr_name)
840 if $meta->has_attribute($attr_name);
845 # check if we can reinitialize
849 # if any local attr is defined
850 return if $self->get_attribute_list;
852 # or any non-declared methods
853 if ( my @methods = values %{ $self->get_method_map } ) {
854 my $metaclass = $self->method_metaclass;
855 foreach my $method ( @methods ) {
856 return if $method->isa("Class::MOP::Method::Generated");
857 # FIXME do we need to enforce this too? return unless $method->isa($metaclass);
867 sub is_immutable { 0 }
869 sub _immutable_options {
870 my ( $self, @args ) = @_;
873 inline_constructor => 1,
874 inline_destructor => 0,
876 immutable_trait => $self->immutable_trait,
877 constructor_name => $self->constructor_name,
878 constructor_class => $self->constructor_class,
879 destructor_class => $self->destructor_class,
885 my ( $self, @args ) = @_;
887 if ( $self->is_mutable ) {
888 $self->_initialize_immutable( $self->_immutable_options(@args) );
889 $self->_rebless_as_immutable(@args);
900 if ( $self->is_immutable ) {
901 my @args = $self->immutable_options;
902 $self->_rebless_as_mutable();
903 $self->_remove_inlined_code(@args);
904 delete $self->{__immutable};
912 sub _rebless_as_immutable {
913 my ( $self, @args ) = @_;
915 $self->{__immutable}{original_class} = ref $self;
917 bless $self => $self->_immutable_metaclass(@args);
920 sub _immutable_metaclass {
921 my ( $self, %args ) = @_;
923 if ( my $class = $args{immutable_metaclass} ) {
927 my $trait = $args{immutable_trait} = $self->immutable_trait
928 || confess "no immutable trait specified for $self";
930 my $meta = $self->meta;
931 my $meta_attr = $meta->find_attribute_by_name("immutable_trait");
935 if ( $meta_attr and $trait eq $meta_attr->default ) {
936 # if the trait is the same as the default we try and pick a
937 # predictable name for the immutable metaclass
938 $class_name = 'Class::MOP::Class::Immutable::' . ref($self);
941 $class_name = join '::', 'Class::MOP::Class::Immutable::CustomTrait',
942 $trait, 'ForMetaClass', ref($self);
946 if Class::MOP::is_class_loaded($class_name);
948 # If the metaclass is a subclass of CMOP::Class which has had
949 # metaclass roles applied (via Moose), then we want to make sure
950 # that we preserve that anonymous class (see Fey::ORM for an
951 # example of where this matters).
953 = $meta->is_immutable
954 ? $meta->get_mutable_metaclass_name
957 my $immutable_meta = $meta_name->create(
959 superclasses => [ ref $self ],
962 Class::MOP::load_class($trait);
963 for my $meth ( Class::MOP::Class->initialize($trait)->get_all_methods ) {
964 my $meth_name = $meth->name;
966 if ( $immutable_meta->find_method_by_name( $meth_name ) ) {
967 $immutable_meta->add_around_method_modifier( $meth_name, $meth->body );
970 $immutable_meta->add_method( $meth_name, $meth->clone );
974 $immutable_meta->make_immutable(
975 inline_constructor => 0,
981 sub _remove_inlined_code {
984 $self->remove_method( $_->name ) for $self->_inlined_methods;
986 delete $self->{__immutable}{inlined_methods};
989 sub _inlined_methods { @{ $_[0]{__immutable}{inlined_methods} || [] } }
991 sub _add_inlined_method {
992 my ( $self, $method ) = @_;
994 push @{ $self->{__immutable}{inlined_methods} ||= [] }, $method;
997 sub _initialize_immutable {
998 my ( $self, %args ) = @_;
1000 $self->{__immutable}{options} = \%args;
1001 $self->_install_inlined_code(%args);
1004 sub _install_inlined_code {
1005 my ( $self, %args ) = @_;
1008 $self->_inline_constructor(%args) if $args{inline_constructor};
1009 $self->_inline_destructor(%args) if $args{inline_destructor};
1012 sub _rebless_as_mutable {
1015 bless $self, $self->get_mutable_metaclass_name;
1020 sub _inline_accessors {
1021 Carp::cluck("The _inline_accessors method is deprecated and will be removed in a future release.\n");
1025 foreach my $attr_name ( $self->get_attribute_list ) {
1026 $self->get_attribute($attr_name)->install_accessors(1);
1030 sub _inline_constructor {
1031 my ( $self, %args ) = @_;
1033 my $name = $args{constructor_name};
1035 if ( $self->has_method($name) && !$args{replace_constructor} ) {
1036 my $class = $self->name;
1037 warn "Not inlining a constructor for $class since it defines"
1038 . " its own constructor.\n"
1039 . "If you are certain you don't need to inline your"
1040 . " constructor, specify inline_constructor => 0 in your"
1041 . " call to $class->meta->make_immutable\n";
1045 my $constructor_class = $args{constructor_class};
1047 Class::MOP::load_class($constructor_class);
1049 my $constructor = $constructor_class->new(
1053 package_name => $self->name,
1057 if ( $args{replace_constructor} or $constructor->can_be_inlined ) {
1058 $self->add_method( $name => $constructor );
1059 $self->_add_inlined_method($constructor);
1063 sub _inline_destructor {
1064 my ( $self, %args ) = @_;
1066 ( exists $args{destructor_class} && defined $args{destructor_class} )
1067 || confess "The 'inline_destructor' option is present, but "
1068 . "no destructor class was specified";
1070 if ( $self->has_method('DESTROY') && ! $args{replace_destructor} ) {
1071 my $class = $self->name;
1072 warn "Not inlining a destructor for $class since it defines"
1073 . " its own destructor.\n";
1077 my $destructor_class = $args{destructor_class};
1079 Class::MOP::load_class($destructor_class);
1081 return unless $destructor_class->is_needed($self);
1083 my $destructor = $destructor_class->new(
1086 package_name => $self->name,
1090 if ( $args{replace_destructor} or $destructor->can_be_inlined ) {
1091 $self->add_method( 'DESTROY' => $destructor );
1092 $self->_add_inlined_method($destructor);
1104 Class::MOP::Class - Class Meta Object
1108 # assuming that class Foo
1109 # has been defined, you can
1111 # use this for introspection ...
1113 # add a method to Foo ...
1114 Foo->meta->add_method( 'bar' => sub {...} )
1116 # get a list of all the classes searched
1117 # the method dispatcher in the correct order
1118 Foo->meta->class_precedence_list()
1120 # remove a method from Foo
1121 Foo->meta->remove_method('bar');
1123 # or use this to actually create classes ...
1125 Class::MOP::Class->create(
1128 superclasses => ['Foo'],
1130 Class::MOP::Attribute->new('$bar'),
1131 Class::MOP::Attribute->new('$baz'),
1134 calculate_bar => sub {...},
1135 construct_baz => sub {...}
1142 The Class Protocol is the largest and most complex part of the
1143 Class::MOP meta-object protocol. It controls the introspection and
1144 manipulation of Perl 5 classes, and it can create them as well. The
1145 best way to understand what this module can do, is to read the
1146 documentation for each of its methods.
1150 C<Class::MOP::Class> is a subclass of L<Class::MOP::Module>.
1154 =head2 Class construction
1156 These methods all create new C<Class::MOP::Class> objects. These
1157 objects can represent existing classes, or they can be used to create
1158 new classes from scratch.
1160 The metaclass object for a given class is a singleton. If you attempt
1161 to create a metaclass for the same class twice, you will just get the
1166 =item B<< Class::MOP::Class->create($package_name, %options) >>
1168 This method creates a new C<Class::MOP::Class> object with the given
1169 package name. It accepts a number of options.
1175 An optional version number for the newly created package.
1179 An optional authority for the newly created package.
1181 =item * superclasses
1183 An optional array reference of superclass names.
1187 An optional hash reference of methods for the class. The keys of the
1188 hash reference are method names, and values are subroutine references.
1192 An optional array reference of L<Class::MOP::Attribute> objects.
1196 =item B<< Class::MOP::Class->create_anon_class(%options) >>
1198 This method works just like C<< Class::MOP::Class->create >> but it
1199 creates an "anonymous" class. In fact, the class does have a name, but
1200 that name is a unique name generated internally by this module.
1202 It accepts the same C<superclasses>, C<methods>, and C<attributes>
1203 parameters that C<create> accepts.
1205 Anonymous classes are destroyed once the metaclass they are attached
1206 to goes out of scope, and will be removed from Perl's internal symbol
1209 All instances of an anonymous class keep a special reference to the
1210 metaclass object, which prevents the metaclass from going out of scope
1211 while any instances exist.
1213 This only works if the instance if based on a hash reference, however.
1215 =item B<< Class::MOP::Class->initialize($package_name, %options) >>
1217 This method will initialize a C<Class::MOP::Class> object for the
1218 named package. Unlike C<create>, this method I<will not> create a new
1221 The purpose of this method is to retrieve a C<Class::MOP::Class>
1222 object for introspecting an existing class.
1224 If an existing C<Class::MOP::Class> object exists for the named
1225 package, it will be returned, and any options provided will be
1228 If the object does not yet exist, it will be created.
1230 The valid options that can be passed to this method are
1231 C<attribute_metaclass>, C<method_metaclass>,
1232 C<wrapped_method_metaclass>, and C<instance_metaclass>. These are all
1233 optional, and default to the appropriate class in the C<Class::MOP>
1238 =head2 Object instance construction and cloning
1240 These methods are all related to creating and/or cloning object
1245 =item B<< $metaclass->clone_object($instance, %params) >>
1247 This method clones an existing object instance. Any parameters you
1248 provide are will override existing attribute values in the object.
1250 This is a convenience method for cloning an object instance, then
1251 blessing it into the appropriate package.
1253 You could implement a clone method in your class, using this method:
1256 my ($self, %params) = @_;
1257 $self->meta->clone_object($self, %params);
1260 =item B<< $metaclass->rebless_instance($instance, %params) >>
1262 This method changes the class of C<$instance> to the metaclass's class.
1264 You can only rebless an instance into a subclass of its current
1265 class. If you pass any additional parameters, these will be treated
1266 like constructor parameters and used to initialize the object's
1267 attributes. Any existing attributes that are already set will be
1270 Before reblessing the instance, this method will call
1271 C<rebless_instance_away> on the instance's current metaclass. This method
1272 will be passed the instance, the new metaclass, and any parameters
1273 specified to C<rebless_instance>. By default, C<rebless_instance_away>
1274 does nothing; it is merely a hook.
1276 =item B<< $metaclass->new_object(%params) >>
1278 This method is used to create a new object of the metaclass's
1279 class. Any parameters you provide are used to initialize the
1280 instance's attributes. A special C<__INSTANCE__> key can be passed to
1281 provide an already generated instance, rather than having Class::MOP
1282 generate it for you. This is mostly useful for using Class::MOP with
1283 foreign classes, which generally generate instances using their own
1286 =item B<< $metaclass->instance_metaclass >>
1288 Returns the class name of the instance metaclass, see
1289 L<Class::MOP::Instance> for more information on the instance
1292 =item B<< $metaclass->get_meta_instance >>
1294 Returns an instance of the C<instance_metaclass> to be used in the
1295 construction of a new instance of the class.
1299 =head2 Informational predicates
1301 These are a few predicate methods for asking information about the
1306 =item B<< $metaclass->is_anon_class >>
1308 This returns true if the class was created by calling C<<
1309 Class::MOP::Class->create_anon_class >>.
1311 =item B<< $metaclass->is_mutable >>
1313 This returns true if the class is still mutable.
1315 =item B<< $metaclass->is_immutable >>
1317 This returns true if the class has been made immutable.
1319 =item B<< $metaclass->is_pristine >>
1321 A class is I<not> pristine if it has non-inherited attributes or if it
1322 has any generated methods.
1326 =head2 Inheritance Relationships
1330 =item B<< $metaclass->superclasses(@superclasses) >>
1332 This is a read-write accessor which represents the superclass
1333 relationships of the metaclass's class.
1335 This is basically sugar around getting and setting C<@ISA>.
1337 =item B<< $metaclass->class_precedence_list >>
1339 This returns a list of all of the class's ancestor classes. The
1340 classes are returned in method dispatch order.
1342 =item B<< $metaclass->linearized_isa >>
1344 This returns a list based on C<class_precedence_list> but with all
1347 =item B<< $metaclass->subclasses >>
1349 This returns a list of all subclasses for this class, even indirect
1352 =item B<< $metaclass->direct_subclasses >>
1354 This returns a list of immediate subclasses for this class, which does not
1355 include indirect subclasses.
1359 =head2 Method introspection
1361 See L<Class::MOP::Package/Method introspection and creation> for
1362 methods that operate only on the current class. Class::MOP::Class adds
1363 introspection capabilities that take inheritance into account.
1367 =item B<< $metaclass->get_all_methods >>
1369 This will traverse the inheritance hierarchy and return a list of all
1370 the L<Class::MOP::Method> objects for this class and its parents.
1372 =item B<< $metaclass->find_method_by_name($method_name) >>
1374 This will return a L<Class::MOP::Method> for the specified
1375 C<$method_name>. If the class does not have the specified method, it
1378 Unlike C<get_method>, this method I<will> look for the named method in
1381 =item B<< $metaclass->get_all_method_names >>
1383 This will return a list of method I<names> for all of this class's
1384 methods, including inherited methods.
1386 =item B<< $metaclass->find_all_methods_by_name($method_name) >>
1388 This method looks for the named method in the class and all of its
1389 parents. It returns every matching method it finds in the inheritance
1390 tree, so it returns a list of methods.
1392 Each method is returned as a hash reference with three keys. The keys
1393 are C<name>, C<class>, and C<code>. The C<code> key has a
1394 L<Class::MOP::Method> object as its value.
1396 The list of methods is distinct.
1398 =item B<< $metaclass->find_next_method_by_name($method_name) >>
1400 This method returns the first method in any superclass matching the
1401 given name. It is effectively the method that C<SUPER::$method_name>
1406 =head2 Attribute introspection and creation
1408 Because Perl 5 does not have a core concept of attributes in classes,
1409 we can only return information about attributes which have been added
1410 via this class's methods. We cannot discover information about
1411 attributes which are defined in terms of "regular" Perl 5 methods.
1415 =item B<< $metaclass->get_attribute($attribute_name) >>
1417 This will return a L<Class::MOP::Attribute> for the specified
1418 C<$attribute_name>. If the class does not have the specified
1419 attribute, it returns C<undef>.
1421 NOTE that get_attribute does not search superclasses, for that you
1422 need to use C<find_attribute_by_name>.
1424 =item B<< $metaclass->has_attribute($attribute_name) >>
1426 Returns a boolean indicating whether or not the class defines the
1427 named attribute. It does not include attributes inherited from parent
1430 =item B<< $metaclass->get_attribute_map >>
1432 Returns a hash reference representing the attributes defined in this
1433 class. The keys are attribute names and the values are
1434 L<Class::MOP::Attribute> objects.
1436 =item B<< $metaclass->get_attribute_list >>
1438 This will return a list of attributes I<names> for all attributes
1439 defined in this class.
1441 =item B<< $metaclass->get_all_attributes >>
1443 This will traverse the inheritance hierarchy and return a list of all
1444 the L<Class::MOP::Attribute> objects for this class and its parents.
1446 =item B<< $metaclass->find_attribute_by_name($attribute_name) >>
1448 This will return a L<Class::MOP::Attribute> for the specified
1449 C<$attribute_name>. If the class does not have the specified
1450 attribute, it returns C<undef>
1452 Unlike C<get_attribute>, this attribute I<will> look for the named
1453 attribute in superclasses.
1455 =item B<< $metaclass->add_attribute(...) >>
1457 This method accepts either an existing L<Class::MOP::Attribute>
1458 object, or parameters suitable for passing to that class's C<new>
1461 The attribute provided will be added to the class.
1463 Any accessor methods defined by the attribute will be added to the
1464 class when the attribute is added.
1466 If an attribute of the same name already exists, the old attribute
1467 will be removed first.
1469 =item B<< $metaclass->remove_attribute($attribute_name) >>
1471 This will remove the named attribute from the class, and
1472 L<Class::MOP::Attribute> object.
1474 Removing an attribute also removes any accessor methods defined by the
1477 However, note that removing an attribute will only affect I<future>
1478 object instances created for this class, not existing instances.
1480 =item B<< $metaclass->attribute_metaclass >>
1482 Returns the class name of the attribute metaclass for this class. By
1483 default, this is L<Class::MOP::Attribute>.
1487 =head2 Class Immutability
1489 Making a class immutable "freezes" the class definition. You can no
1490 longer call methods which alter the class, such as adding or removing
1491 methods or attributes.
1493 Making a class immutable lets us optimize the class by inlining some
1494 methods, and also allows us to optimize some methods on the metaclass
1497 After immutabilization, the metaclass object will cache most
1498 informational methods such as C<get_method_map> and
1499 C<get_all_attributes>. Methods which would alter the class, such as
1500 C<add_attribute>, C<add_method>, and so on will throw an error on an
1501 immutable metaclass object.
1503 The immutabilization system in L<Moose> takes much greater advantage
1504 of the inlining features than Class::MOP itself does.
1508 =item B<< $metaclass->make_immutable(%options) >>
1510 This method will create an immutable transformer and uses it to make
1511 the class and its metaclass object immutable.
1513 This method accepts the following options:
1517 =item * inline_constructor
1519 =item * inline_destructor
1521 These are all booleans indicating whether the specified method(s)
1524 By default, accessors and the constructor are inlined, but not the
1527 =item * immutable_trait
1529 The name of a class which will be used as a parent class for the
1530 metaclass object being made immutable. This "trait" implements the
1531 post-immutability functionality of the metaclass (but not the
1532 transformation itself).
1534 This defaults to L<Class::MOP::Class::Immutable::Trait>.
1536 =item * constructor_name
1538 This is the constructor method name. This defaults to "new".
1540 =item * constructor_class
1542 The name of the method metaclass for constructors. It will be used to
1543 generate the inlined constructor. This defaults to
1544 "Class::MOP::Method::Constructor".
1546 =item * replace_constructor
1548 This is a boolean indicating whether an existing constructor should be
1549 replaced when inlining a constructor. This defaults to false.
1551 =item * destructor_class
1553 The name of the method metaclass for destructors. It will be used to
1554 generate the inlined destructor. This defaults to
1555 "Class::MOP::Method::Denstructor".
1557 =item * replace_destructor
1559 This is a boolean indicating whether an existing destructor should be
1560 replaced when inlining a destructor. This defaults to false.
1564 =item B<< $metaclass->make_mutable >>
1566 Calling this method reverse the immutabilization transformation.
1570 =head2 Method Modifiers
1572 Method modifiers are hooks which allow a method to be wrapped with
1573 I<before>, I<after> and I<around> method modifiers. Every time a
1574 method is called, it's modifiers are also called.
1576 A class can modify its own methods, as well as methods defined in
1579 =head3 How method modifiers work?
1581 Method modifiers work by wrapping the original method and then
1582 replacing it in the class's symbol table. The wrappers will handle
1583 calling all the modifiers in the appropriate order and preserving the
1584 calling context for the original method.
1586 The return values of C<before> and C<after> modifiers are
1587 ignored. This is because their purpose is B<not> to filter the input
1588 and output of the primary method (this is done with an I<around>
1591 This may seem like an odd restriction to some, but doing this allows
1592 for simple code to be added at the beginning or end of a method call
1593 without altering the function of the wrapped method or placing any
1594 extra responsibility on the code of the modifier.
1596 Of course if you have more complex needs, you can use the C<around>
1597 modifier which allows you to change both the parameters passed to the
1598 wrapped method, as well as its return value.
1600 Before and around modifiers are called in last-defined-first-called
1601 order, while after modifiers are called in first-defined-first-called
1602 order. So the call tree might looks something like this:
1614 =head3 What is the performance impact?
1616 Of course there is a performance cost associated with method
1617 modifiers, but we have made every effort to make that cost directly
1618 proportional to the number of modifier features you utilize.
1620 The wrapping method does it's best to B<only> do as much work as it
1621 absolutely needs to. In order to do this we have moved some of the
1622 performance costs to set-up time, where they are easier to amortize.
1624 All this said, our benchmarks have indicated the following:
1626 simple wrapper with no modifiers 100% slower
1627 simple wrapper with simple before modifier 400% slower
1628 simple wrapper with simple after modifier 450% slower
1629 simple wrapper with simple around modifier 500-550% slower
1630 simple wrapper with all 3 modifiers 1100% slower
1632 These numbers may seem daunting, but you must remember, every feature
1633 comes with some cost. To put things in perspective, just doing a
1634 simple C<AUTOLOAD> which does nothing but extract the name of the
1635 method called and return it costs about 400% over a normal method
1640 =item B<< $metaclass->add_before_method_modifier($method_name, $code) >>
1642 This wraps the specified method with the supplied subroutine
1643 reference. The modifier will be called as a method itself, and will
1644 receive the same arguments as are passed to the method.
1646 When the modifier exits, the wrapped method will be called.
1648 The return value of the modifier will be ignored.
1650 =item B<< $metaclass->add_after_method_modifier($method_name, $code) >>
1652 This wraps the specified method with the supplied subroutine
1653 reference. The modifier will be called as a method itself, and will
1654 receive the same arguments as are passed to the method.
1656 When the wrapped methods exits, the modifier will be called.
1658 The return value of the modifier will be ignored.
1660 =item B<< $metaclass->add_around_method_modifier($method_name, $code) >>
1662 This wraps the specified method with the supplied subroutine
1665 The first argument passed to the modifier will be a subroutine
1666 reference to the wrapped method. The second argument is the object,
1667 and after that come any arguments passed when the method is called.
1669 The around modifier can choose to call the original method, as well as
1670 what arguments to pass if it does so.
1672 The return value of the modifier is what will be seen by the caller.
1676 =head2 Introspection
1680 =item B<< Class::MOP::Class->meta >>
1682 This will return a L<Class::MOP::Class> instance for this class.
1684 It should also be noted that L<Class::MOP> will actually bootstrap
1685 this module by installing a number of attribute meta-objects into its
1692 Stevan Little E<lt>stevan@iinteractive.comE<gt>
1694 =head1 COPYRIGHT AND LICENSE
1696 Copyright 2006-2009 by Infinity Interactive, Inc.
1698 L<http://www.iinteractive.com>
1700 This library is free software; you can redistribute it and/or modify
1701 it under the same terms as Perl itself.