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', 'weaken';
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});
327 # Instance Construction & Cloning
333 # we need to protect the integrity of the
334 # Class::MOP::Class singletons here, so we
335 # delegate this to &construct_class_instance
336 # which will deal with the singletons
337 return $class->_construct_class_instance(@_)
338 if $class->name->isa('Class::MOP::Class');
339 return $class->_construct_instance(@_);
342 sub _construct_instance {
344 my $params = @_ == 1 ? $_[0] : {@_};
345 my $meta_instance = $class->get_meta_instance();
347 # the code below is almost certainly incorrect
348 # but this is foreign inheritance, so we might
349 # have to kludge it in the end.
350 my $instance = $params->{__INSTANCE__} || $meta_instance->create_instance();
351 foreach my $attr ($class->get_all_attributes()) {
352 $attr->initialize_instance_slot($meta_instance, $instance, $params);
355 # this will only work for a HASH instance type
356 if ($class->is_anon_class) {
357 (reftype($instance) eq 'HASH')
358 || confess "Currently only HASH based instances are supported with instance of anon-classes";
360 # At some point we should make this official
361 # as a reserved slot name, but right now I am
362 # going to keep it here.
363 # my $RESERVED_MOP_SLOT = '__MOP__';
364 $instance->{'__MOP__'} = $class;
370 sub get_meta_instance {
372 $self->{'_meta_instance'} ||= $self->_create_meta_instance();
375 sub _create_meta_instance {
378 my $instance = $self->instance_metaclass->new(
379 associated_metaclass => $self,
380 attributes => [ $self->get_all_attributes() ],
383 $self->add_meta_instance_dependencies()
384 if $instance->is_dependent_on_superclasses();
391 my $instance = shift;
392 (blessed($instance) && $instance->isa($class->name))
393 || confess "You must pass an instance of the metaclass (" . (ref $class ? $class->name : $class) . "), not ($instance)";
396 # we need to protect the integrity of the
397 # Class::MOP::Class singletons here, they
398 # should not be cloned.
399 return $instance if $instance->isa('Class::MOP::Class');
400 $class->_clone_instance($instance, @_);
403 sub _clone_instance {
404 my ($class, $instance, %params) = @_;
406 || confess "You can only clone instances, ($instance) is not a blessed instance";
407 my $meta_instance = $class->get_meta_instance();
408 my $clone = $meta_instance->clone_instance($instance);
409 foreach my $attr ($class->get_all_attributes()) {
410 if ( defined( my $init_arg = $attr->init_arg ) ) {
411 if (exists $params{$init_arg}) {
412 $attr->set_value($clone, $params{$init_arg});
419 sub rebless_instance {
420 my ($self, $instance, %params) = @_;
422 my $old_metaclass = Class::MOP::class_of($instance);
424 my $old_class = $old_metaclass ? $old_metaclass->name : blessed($instance);
425 $self->name->isa($old_class)
426 || confess "You may rebless only into a subclass of ($old_class), of which (". $self->name .") isn't.";
428 $old_metaclass->rebless_instance_away($instance, $self, %params)
431 my $meta_instance = $self->get_meta_instance();
434 # we use $_[1] here because of t/306_rebless_overload.t regressions on 5.8.8
435 $meta_instance->rebless_instance_structure($_[1], $self);
437 foreach my $attr ( $self->get_all_attributes ) {
438 if ( $attr->has_value($instance) ) {
439 if ( defined( my $init_arg = $attr->init_arg ) ) {
440 $params{$init_arg} = $attr->get_value($instance)
441 unless exists $params{$init_arg};
444 $attr->set_value($instance, $attr->get_value($instance));
449 foreach my $attr ($self->get_all_attributes) {
450 $attr->initialize_instance_slot($meta_instance, $instance, \%params);
456 sub rebless_instance_away {
457 # this intentionally does nothing, it is just a hook
464 my $var_spec = { sigil => '@', type => 'ARRAY', name => 'ISA' };
467 @{$self->get_package_symbol($var_spec)} = @supers;
470 # on 5.8 and below, we need to call
471 # a method to get Perl to detect
472 # a cycle in the class hierarchy
473 my $class = $self->name;
477 # we need to check the metaclass
478 # compatibility here so that we can
479 # be sure that the superclass is
480 # not potentially creating an issues
481 # we don't know about
483 $self->_check_metaclass_compatibility();
484 $self->_superclasses_updated();
486 @{$self->get_package_symbol($var_spec)};
489 sub _superclasses_updated {
491 $self->update_meta_instance_dependencies();
496 my $super_class = $self->name;
498 return @{ $super_class->mro::get_isarev() };
501 sub direct_subclasses {
503 my $super_class = $self->name;
508 } Class::MOP::Class->initialize($_)->superclasses
513 return @{ mro::get_linear_isa( (shift)->name ) };
516 sub class_precedence_list {
518 my $name = $self->name;
520 unless (Class::MOP::IS_RUNNING_ON_5_10()) {
522 # We need to check for circular inheritance here
523 # if we are are not on 5.10, cause 5.8 detects it
524 # late. This will do nothing if all is well, and
525 # blow up otherwise. Yes, it's an ugly hack, better
526 # suggestions are welcome.
528 ($name || return)->isa('This is a test for circular inheritance')
531 # if our mro is c3, we can
532 # just grab the linear_isa
533 if (mro::get_mro($name) eq 'c3') {
534 return @{ mro::get_linear_isa($name) }
538 # we can't grab the linear_isa for dfs
539 # since it has all the duplicates
544 $self->initialize($_)->class_precedence_list()
545 } $self->superclasses()
553 my $fetch_and_prepare_method = sub {
554 my ($self, $method_name) = @_;
555 my $wrapped_metaclass = $self->wrapped_method_metaclass;
557 my $method = $self->get_method($method_name);
558 # if we dont have local ...
560 # try to find the next method
561 $method = $self->find_next_method_by_name($method_name);
562 # die if it does not exist
564 || confess "The method '$method_name' was not found in the inheritance hierarchy for " . $self->name;
565 # and now make sure to wrap it
566 # even if it is already wrapped
567 # because we need a new sub ref
568 $method = $wrapped_metaclass->wrap($method,
569 package_name => $self->name,
570 name => $method_name,
574 # now make sure we wrap it properly
575 $method = $wrapped_metaclass->wrap($method,
576 package_name => $self->name,
577 name => $method_name,
578 ) unless $method->isa($wrapped_metaclass);
580 $self->add_method($method_name => $method);
584 sub add_before_method_modifier {
585 my ($self, $method_name, $method_modifier) = @_;
586 (defined $method_name && $method_name)
587 || confess "You must pass in a method name";
588 my $method = $fetch_and_prepare_method->($self, $method_name);
589 $method->add_before_modifier(
590 subname(':before' => $method_modifier)
594 sub add_after_method_modifier {
595 my ($self, $method_name, $method_modifier) = @_;
596 (defined $method_name && $method_name)
597 || confess "You must pass in a method name";
598 my $method = $fetch_and_prepare_method->($self, $method_name);
599 $method->add_after_modifier(
600 subname(':after' => $method_modifier)
604 sub add_around_method_modifier {
605 my ($self, $method_name, $method_modifier) = @_;
606 (defined $method_name && $method_name)
607 || confess "You must pass in a method name";
608 my $method = $fetch_and_prepare_method->($self, $method_name);
609 $method->add_around_modifier(
610 subname(':around' => $method_modifier)
615 # the methods above used to be named like this:
616 # ${pkg}::${method}:(before|after|around)
617 # but this proved problematic when using one modifier
618 # to wrap multiple methods (something which is likely
619 # to happen pretty regularly IMO). So instead of naming
620 # it like this, I have chosen to just name them purely
621 # with their modifier names, like so:
622 # :(before|after|around)
623 # The fact is that in a stack trace, it will be fairly
624 # evident from the context what method they are attached
625 # to, and so don't need the fully qualified name.
628 sub find_method_by_name {
629 my ($self, $method_name) = @_;
630 (defined $method_name && $method_name)
631 || confess "You must define a method name to find";
632 foreach my $class ($self->linearized_isa) {
633 my $method = $self->initialize($class)->get_method($method_name);
634 return $method if defined $method;
639 sub get_all_methods {
641 my %methods = map { %{ $self->initialize($_)->get_method_map } } reverse $self->linearized_isa;
642 return values %methods;
645 sub get_all_method_names {
648 return grep { !$uniq{$_}++ } map { $self->initialize($_)->get_method_list } $self->linearized_isa;
651 sub find_all_methods_by_name {
652 my ($self, $method_name) = @_;
653 (defined $method_name && $method_name)
654 || confess "You must define a method name to find";
656 foreach my $class ($self->linearized_isa) {
657 # fetch the meta-class ...
658 my $meta = $self->initialize($class);
660 name => $method_name,
662 code => $meta->get_method($method_name)
663 } if $meta->has_method($method_name);
668 sub find_next_method_by_name {
669 my ($self, $method_name) = @_;
670 (defined $method_name && $method_name)
671 || confess "You must define a method name to find";
672 my @cpl = $self->linearized_isa;
673 shift @cpl; # discard ourselves
674 foreach my $class (@cpl) {
675 my $method = $self->initialize($class)->get_method($method_name);
676 return $method if defined $method;
685 # either we have an attribute object already
686 # or we need to create one from the args provided
687 my $attribute = blessed($_[0]) ? $_[0] : $self->attribute_metaclass->new(@_);
688 # make sure it is derived from the correct type though
689 ($attribute->isa('Class::MOP::Attribute'))
690 || confess "Your attribute must be an instance of Class::MOP::Attribute (or a subclass)";
692 # first we attach our new attribute
693 # because it might need certain information
694 # about the class which it is attached to
695 $attribute->attach_to_class($self);
697 my $attr_name = $attribute->name;
699 # then we remove attributes of a conflicting
700 # name here so that we can properly detach
701 # the old attr object, and remove any
702 # accessors it would have generated
703 if ( $self->has_attribute($attr_name) ) {
704 $self->remove_attribute($attr_name);
706 $self->invalidate_meta_instances();
709 # get our count of previously inserted attributes and
710 # increment by one so this attribute knows its order
711 my $order = (scalar keys %{$self->get_attribute_map});
712 $attribute->_set_insertion_order($order);
714 # then onto installing the new accessors
715 $self->get_attribute_map->{$attr_name} = $attribute;
717 # invalidate package flag here
721 eval { $attribute->install_accessors() };
725 $self->remove_attribute($attr_name);
732 sub update_meta_instance_dependencies {
735 if ( $self->{meta_instance_dependencies} ) {
736 return $self->add_meta_instance_dependencies;
740 sub add_meta_instance_dependencies {
743 $self->remove_meta_instance_dependencies;
745 my @attrs = $self->get_all_attributes();
748 my @classes = grep { not $seen{$_->name}++ } map { $_->associated_class } @attrs;
750 foreach my $class ( @classes ) {
751 $class->add_dependent_meta_instance($self);
754 $self->{meta_instance_dependencies} = \@classes;
757 sub remove_meta_instance_dependencies {
760 if ( my $classes = delete $self->{meta_instance_dependencies} ) {
761 foreach my $class ( @$classes ) {
762 $class->remove_dependent_meta_instance($self);
772 sub add_dependent_meta_instance {
773 my ( $self, $metaclass ) = @_;
774 push @{ $self->{dependent_meta_instances} }, $metaclass;
777 sub remove_dependent_meta_instance {
778 my ( $self, $metaclass ) = @_;
779 my $name = $metaclass->name;
780 @$_ = grep { $_->name ne $name } @$_ for $self->{dependent_meta_instances};
783 sub invalidate_meta_instances {
785 $_->invalidate_meta_instance() for $self, @{ $self->{dependent_meta_instances} };
788 sub invalidate_meta_instance {
790 undef $self->{_meta_instance};
794 my ($self, $attribute_name) = @_;
795 (defined $attribute_name)
796 || confess "You must define an attribute name";
797 exists $self->get_attribute_map->{$attribute_name};
801 my ($self, $attribute_name) = @_;
802 (defined $attribute_name)
803 || confess "You must define an attribute name";
804 return $self->get_attribute_map->{$attribute_name}
806 # this will return undef anyway, so no need ...
807 # if $self->has_attribute($attribute_name);
811 sub remove_attribute {
812 my ($self, $attribute_name) = @_;
813 (defined $attribute_name)
814 || confess "You must define an attribute name";
815 my $removed_attribute = $self->get_attribute_map->{$attribute_name};
816 return unless defined $removed_attribute;
817 delete $self->get_attribute_map->{$attribute_name};
818 $self->invalidate_meta_instances();
819 $removed_attribute->remove_accessors();
820 $removed_attribute->detach_from_class();
821 return $removed_attribute;
824 sub get_attribute_list {
826 keys %{$self->get_attribute_map};
829 sub get_all_attributes {
831 my %attrs = map { %{ $self->initialize($_)->get_attribute_map } } reverse $self->linearized_isa;
832 return values %attrs;
835 sub find_attribute_by_name {
836 my ($self, $attr_name) = @_;
837 foreach my $class ($self->linearized_isa) {
838 # fetch the meta-class ...
839 my $meta = $self->initialize($class);
840 return $meta->get_attribute($attr_name)
841 if $meta->has_attribute($attr_name);
846 # check if we can reinitialize
850 # if any local attr is defined
851 return if $self->get_attribute_list;
853 # or any non-declared methods
854 if ( my @methods = values %{ $self->get_method_map } ) {
855 my $metaclass = $self->method_metaclass;
856 foreach my $method ( @methods ) {
857 return if $method->isa("Class::MOP::Method::Generated");
858 # FIXME do we need to enforce this too? return unless $method->isa($metaclass);
868 sub is_immutable { 0 }
870 sub _immutable_options {
871 my ( $self, @args ) = @_;
874 inline_constructor => 1,
875 inline_destructor => 0,
877 immutable_trait => $self->immutable_trait,
878 constructor_name => $self->constructor_name,
879 constructor_class => $self->constructor_class,
880 destructor_class => $self->destructor_class,
886 my ( $self, @args ) = @_;
888 if ( $self->is_mutable ) {
889 $self->_initialize_immutable( $self->_immutable_options(@args) );
890 $self->_rebless_as_immutable(@args);
901 if ( $self->is_immutable ) {
902 my @args = $self->immutable_options;
903 $self->_rebless_as_mutable();
904 $self->_remove_inlined_code(@args);
905 delete $self->{__immutable};
913 sub _rebless_as_immutable {
914 my ( $self, @args ) = @_;
916 $self->{__immutable}{original_class} = ref $self;
918 bless $self => $self->_immutable_metaclass(@args);
921 sub _immutable_metaclass {
922 my ( $self, %args ) = @_;
924 if ( my $class = $args{immutable_metaclass} ) {
928 my $trait = $args{immutable_trait} = $self->immutable_trait
929 || confess "no immutable trait specified for $self";
931 my $meta = $self->meta;
932 my $meta_attr = $meta->find_attribute_by_name("immutable_trait");
936 if ( $meta_attr and $trait eq $meta_attr->default ) {
937 # if the trait is the same as the default we try and pick a
938 # predictable name for the immutable metaclass
939 $class_name = 'Class::MOP::Class::Immutable::' . ref($self);
942 $class_name = join '::', 'Class::MOP::Class::Immutable::CustomTrait',
943 $trait, 'ForMetaClass', ref($self);
947 if Class::MOP::is_class_loaded($class_name);
949 # If the metaclass is a subclass of CMOP::Class which has had
950 # metaclass roles applied (via Moose), then we want to make sure
951 # that we preserve that anonymous class (see Fey::ORM for an
952 # example of where this matters).
954 = $meta->is_immutable
955 ? $meta->get_mutable_metaclass_name
958 my $immutable_meta = $meta_name->create(
960 superclasses => [ ref $self ],
963 Class::MOP::load_class($trait);
964 for my $meth ( Class::MOP::Class->initialize($trait)->get_all_methods ) {
965 my $meth_name = $meth->name;
967 if ( $immutable_meta->find_method_by_name( $meth_name ) ) {
968 $immutable_meta->add_around_method_modifier( $meth_name, $meth->body );
971 $immutable_meta->add_method( $meth_name, $meth->clone );
975 $immutable_meta->make_immutable(
976 inline_constructor => 0,
982 sub _remove_inlined_code {
985 $self->remove_method( $_->name ) for $self->_inlined_methods;
987 delete $self->{__immutable}{inlined_methods};
990 sub _inlined_methods { @{ $_[0]{__immutable}{inlined_methods} || [] } }
992 sub _add_inlined_method {
993 my ( $self, $method ) = @_;
995 push @{ $self->{__immutable}{inlined_methods} ||= [] }, $method;
998 sub _initialize_immutable {
999 my ( $self, %args ) = @_;
1001 $self->{__immutable}{options} = \%args;
1002 $self->_install_inlined_code(%args);
1005 sub _install_inlined_code {
1006 my ( $self, %args ) = @_;
1009 $self->_inline_constructor(%args) if $args{inline_constructor};
1010 $self->_inline_destructor(%args) if $args{inline_destructor};
1013 sub _rebless_as_mutable {
1016 bless $self, $self->get_mutable_metaclass_name;
1021 sub _inline_accessors {
1022 Carp::cluck("The _inline_accessors method is deprecated and will be removed in a future release.\n");
1026 foreach my $attr_name ( $self->get_attribute_list ) {
1027 $self->get_attribute($attr_name)->install_accessors(1);
1031 sub _inline_constructor {
1032 my ( $self, %args ) = @_;
1034 my $name = $args{constructor_name};
1036 if ( $self->has_method($name) && !$args{replace_constructor} ) {
1037 my $class = $self->name;
1038 warn "Not inlining a constructor for $class since it defines"
1039 . " its own constructor.\n"
1040 . "If you are certain you don't need to inline your"
1041 . " constructor, specify inline_constructor => 0 in your"
1042 . " call to $class->meta->make_immutable\n";
1046 my $constructor_class = $args{constructor_class};
1048 Class::MOP::load_class($constructor_class);
1050 my $constructor = $constructor_class->new(
1054 package_name => $self->name,
1058 if ( $args{replace_constructor} or $constructor->can_be_inlined ) {
1059 $self->add_method( $name => $constructor );
1060 $self->_add_inlined_method($constructor);
1064 sub _inline_destructor {
1065 my ( $self, %args ) = @_;
1067 ( exists $args{destructor_class} && defined $args{destructor_class} )
1068 || confess "The 'inline_destructor' option is present, but "
1069 . "no destructor class was specified";
1071 if ( $self->has_method('DESTROY') && ! $args{replace_destructor} ) {
1072 my $class = $self->name;
1073 warn "Not inlining a destructor for $class since it defines"
1074 . " its own destructor.\n";
1078 my $destructor_class = $args{destructor_class};
1080 Class::MOP::load_class($destructor_class);
1082 return unless $destructor_class->is_needed($self);
1084 my $destructor = $destructor_class->new(
1087 package_name => $self->name,
1091 if ( $args{replace_destructor} or $destructor->can_be_inlined ) {
1092 $self->add_method( 'DESTROY' => $destructor );
1093 $self->_add_inlined_method($destructor);
1105 Class::MOP::Class - Class Meta Object
1109 # assuming that class Foo
1110 # has been defined, you can
1112 # use this for introspection ...
1114 # add a method to Foo ...
1115 Foo->meta->add_method( 'bar' => sub {...} )
1117 # get a list of all the classes searched
1118 # the method dispatcher in the correct order
1119 Foo->meta->class_precedence_list()
1121 # remove a method from Foo
1122 Foo->meta->remove_method('bar');
1124 # or use this to actually create classes ...
1126 Class::MOP::Class->create(
1129 superclasses => ['Foo'],
1131 Class::MOP::Attribute->new('$bar'),
1132 Class::MOP::Attribute->new('$baz'),
1135 calculate_bar => sub {...},
1136 construct_baz => sub {...}
1143 The Class Protocol is the largest and most complex part of the
1144 Class::MOP meta-object protocol. It controls the introspection and
1145 manipulation of Perl 5 classes, and it can create them as well. The
1146 best way to understand what this module can do, is to read the
1147 documentation for each of its methods.
1151 C<Class::MOP::Class> is a subclass of L<Class::MOP::Module>.
1155 =head2 Class construction
1157 These methods all create new C<Class::MOP::Class> objects. These
1158 objects can represent existing classes, or they can be used to create
1159 new classes from scratch.
1161 The metaclass object for a given class is a singleton. If you attempt
1162 to create a metaclass for the same class twice, you will just get the
1167 =item B<< Class::MOP::Class->create($package_name, %options) >>
1169 This method creates a new C<Class::MOP::Class> object with the given
1170 package name. It accepts a number of options.
1176 An optional version number for the newly created package.
1180 An optional authority for the newly created package.
1182 =item * superclasses
1184 An optional array reference of superclass names.
1188 An optional hash reference of methods for the class. The keys of the
1189 hash reference are method names, and values are subroutine references.
1193 An optional array reference of L<Class::MOP::Attribute> objects.
1197 =item B<< Class::MOP::Class->create_anon_class(%options) >>
1199 This method works just like C<< Class::MOP::Class->create >> but it
1200 creates an "anonymous" class. In fact, the class does have a name, but
1201 that name is a unique name generated internally by this module.
1203 It accepts the same C<superclasses>, C<methods>, and C<attributes>
1204 parameters that C<create> accepts.
1206 Anonymous classes are destroyed once the metaclass they are attached
1207 to goes out of scope, and will be removed from Perl's internal symbol
1210 All instances of an anonymous class keep a special reference to the
1211 metaclass object, which prevents the metaclass from going out of scope
1212 while any instances exist.
1214 This only works if the instance if based on a hash reference, however.
1216 =item B<< Class::MOP::Class->initialize($package_name, %options) >>
1218 This method will initialize a C<Class::MOP::Class> object for the
1219 named package. Unlike C<create>, this method I<will not> create a new
1222 The purpose of this method is to retrieve a C<Class::MOP::Class>
1223 object for introspecting an existing class.
1225 If an existing C<Class::MOP::Class> object exists for the named
1226 package, it will be returned, and any options provided will be
1229 If the object does not yet exist, it will be created.
1231 The valid options that can be passed to this method are
1232 C<attribute_metaclass>, C<method_metaclass>,
1233 C<wrapped_method_metaclass>, and C<instance_metaclass>. These are all
1234 optional, and default to the appropriate class in the C<Class::MOP>
1239 =head2 Object instance construction and cloning
1241 These methods are all related to creating and/or cloning object
1246 =item B<< $metaclass->clone_object($instance, %params) >>
1248 This method clones an existing object instance. Any parameters you
1249 provide are will override existing attribute values in the object.
1251 This is a convenience method for cloning an object instance, then
1252 blessing it into the appropriate package.
1254 You could implement a clone method in your class, using this method:
1257 my ($self, %params) = @_;
1258 $self->meta->clone_object($self, %params);
1261 =item B<< $metaclass->rebless_instance($instance, %params) >>
1263 This method changes the class of C<$instance> to the metaclass's class.
1265 You can only rebless an instance into a subclass of its current
1266 class. If you pass any additional parameters, these will be treated
1267 like constructor parameters and used to initialize the object's
1268 attributes. Any existing attributes that are already set will be
1271 Before reblessing the instance, this method will call
1272 C<rebless_instance_away> on the instance's current metaclass. This method
1273 will be passed the instance, the new metaclass, and any parameters
1274 specified to C<rebless_instance>. By default, C<rebless_instance_away>
1275 does nothing; it is merely a hook.
1277 =item B<< $metaclass->new_object(%params) >>
1279 This method is used to create a new object of the metaclass's
1280 class. Any parameters you provide are used to initialize the
1281 instance's attributes. A special C<__INSTANCE__> key can be passed to
1282 provide an already generated instance, rather than having Class::MOP
1283 generate it for you. This is mostly useful for using Class::MOP with
1284 foreign classes, which generally generate instances using their own
1287 =item B<< $metaclass->instance_metaclass >>
1289 Returns the class name of the instance metaclass, see
1290 L<Class::MOP::Instance> for more information on the instance
1293 =item B<< $metaclass->get_meta_instance >>
1295 Returns an instance of the C<instance_metaclass> to be used in the
1296 construction of a new instance of the class.
1300 =head2 Informational predicates
1302 These are a few predicate methods for asking information about the
1307 =item B<< $metaclass->is_anon_class >>
1309 This returns true if the class was created by calling C<<
1310 Class::MOP::Class->create_anon_class >>.
1312 =item B<< $metaclass->is_mutable >>
1314 This returns true if the class is still mutable.
1316 =item B<< $metaclass->is_immutable >>
1318 This returns true if the class has been made immutable.
1320 =item B<< $metaclass->is_pristine >>
1322 A class is I<not> pristine if it has non-inherited attributes or if it
1323 has any generated methods.
1327 =head2 Inheritance Relationships
1331 =item B<< $metaclass->superclasses(@superclasses) >>
1333 This is a read-write accessor which represents the superclass
1334 relationships of the metaclass's class.
1336 This is basically sugar around getting and setting C<@ISA>.
1338 =item B<< $metaclass->class_precedence_list >>
1340 This returns a list of all of the class's ancestor classes. The
1341 classes are returned in method dispatch order.
1343 =item B<< $metaclass->linearized_isa >>
1345 This returns a list based on C<class_precedence_list> but with all
1348 =item B<< $metaclass->subclasses >>
1350 This returns a list of all subclasses for this class, even indirect
1353 =item B<< $metaclass->direct_subclasses >>
1355 This returns a list of immediate subclasses for this class, which does not
1356 include indirect subclasses.
1360 =head2 Method introspection
1362 See L<Class::MOP::Package/Method introspection and creation> for
1363 methods that operate only on the current class. Class::MOP::Class adds
1364 introspection capabilities that take inheritance into account.
1368 =item B<< $metaclass->get_all_methods >>
1370 This will traverse the inheritance hierarchy and return a list of all
1371 the L<Class::MOP::Method> objects for this class and its parents.
1373 =item B<< $metaclass->find_method_by_name($method_name) >>
1375 This will return a L<Class::MOP::Method> for the specified
1376 C<$method_name>. If the class does not have the specified method, it
1379 Unlike C<get_method>, this method I<will> look for the named method in
1382 =item B<< $metaclass->get_all_method_names >>
1384 This will return a list of method I<names> for all of this class's
1385 methods, including inherited methods.
1387 =item B<< $metaclass->find_all_methods_by_name($method_name) >>
1389 This method looks for the named method in the class and all of its
1390 parents. It returns every matching method it finds in the inheritance
1391 tree, so it returns a list of methods.
1393 Each method is returned as a hash reference with three keys. The keys
1394 are C<name>, C<class>, and C<code>. The C<code> key has a
1395 L<Class::MOP::Method> object as its value.
1397 The list of methods is distinct.
1399 =item B<< $metaclass->find_next_method_by_name($method_name) >>
1401 This method returns the first method in any superclass matching the
1402 given name. It is effectively the method that C<SUPER::$method_name>
1407 =head2 Attribute introspection and creation
1409 Because Perl 5 does not have a core concept of attributes in classes,
1410 we can only return information about attributes which have been added
1411 via this class's methods. We cannot discover information about
1412 attributes which are defined in terms of "regular" Perl 5 methods.
1416 =item B<< $metaclass->get_attribute($attribute_name) >>
1418 This will return a L<Class::MOP::Attribute> for the specified
1419 C<$attribute_name>. If the class does not have the specified
1420 attribute, it returns C<undef>.
1422 NOTE that get_attribute does not search superclasses, for that you
1423 need to use C<find_attribute_by_name>.
1425 =item B<< $metaclass->has_attribute($attribute_name) >>
1427 Returns a boolean indicating whether or not the class defines the
1428 named attribute. It does not include attributes inherited from parent
1431 =item B<< $metaclass->get_attribute_map >>
1433 Returns a hash reference representing the attributes defined in this
1434 class. The keys are attribute names and the values are
1435 L<Class::MOP::Attribute> objects.
1437 =item B<< $metaclass->get_attribute_list >>
1439 This will return a list of attributes I<names> for all attributes
1440 defined in this class.
1442 =item B<< $metaclass->get_all_attributes >>
1444 This will traverse the inheritance hierarchy and return a list of all
1445 the L<Class::MOP::Attribute> objects for this class and its parents.
1447 =item B<< $metaclass->find_attribute_by_name($attribute_name) >>
1449 This will return a L<Class::MOP::Attribute> for the specified
1450 C<$attribute_name>. If the class does not have the specified
1451 attribute, it returns C<undef>
1453 Unlike C<get_attribute>, this attribute I<will> look for the named
1454 attribute in superclasses.
1456 =item B<< $metaclass->add_attribute(...) >>
1458 This method accepts either an existing L<Class::MOP::Attribute>
1459 object, or parameters suitable for passing to that class's C<new>
1462 The attribute provided will be added to the class.
1464 Any accessor methods defined by the attribute will be added to the
1465 class when the attribute is added.
1467 If an attribute of the same name already exists, the old attribute
1468 will be removed first.
1470 =item B<< $metaclass->remove_attribute($attribute_name) >>
1472 This will remove the named attribute from the class, and
1473 L<Class::MOP::Attribute> object.
1475 Removing an attribute also removes any accessor methods defined by the
1478 However, note that removing an attribute will only affect I<future>
1479 object instances created for this class, not existing instances.
1481 =item B<< $metaclass->attribute_metaclass >>
1483 Returns the class name of the attribute metaclass for this class. By
1484 default, this is L<Class::MOP::Attribute>.
1488 =head2 Class Immutability
1490 Making a class immutable "freezes" the class definition. You can no
1491 longer call methods which alter the class, such as adding or removing
1492 methods or attributes.
1494 Making a class immutable lets us optimize the class by inlining some
1495 methods, and also allows us to optimize some methods on the metaclass
1498 After immutabilization, the metaclass object will cache most
1499 informational methods such as C<get_method_map> and
1500 C<get_all_attributes>. Methods which would alter the class, such as
1501 C<add_attribute>, C<add_method>, and so on will throw an error on an
1502 immutable metaclass object.
1504 The immutabilization system in L<Moose> takes much greater advantage
1505 of the inlining features than Class::MOP itself does.
1509 =item B<< $metaclass->make_immutable(%options) >>
1511 This method will create an immutable transformer and uses it to make
1512 the class and its metaclass object immutable.
1514 This method accepts the following options:
1518 =item * inline_constructor
1520 =item * inline_destructor
1522 These are all booleans indicating whether the specified method(s)
1525 By default, accessors and the constructor are inlined, but not the
1528 =item * immutable_trait
1530 The name of a class which will be used as a parent class for the
1531 metaclass object being made immutable. This "trait" implements the
1532 post-immutability functionality of the metaclass (but not the
1533 transformation itself).
1535 This defaults to L<Class::MOP::Class::Immutable::Trait>.
1537 =item * constructor_name
1539 This is the constructor method name. This defaults to "new".
1541 =item * constructor_class
1543 The name of the method metaclass for constructors. It will be used to
1544 generate the inlined constructor. This defaults to
1545 "Class::MOP::Method::Constructor".
1547 =item * replace_constructor
1549 This is a boolean indicating whether an existing constructor should be
1550 replaced when inlining a constructor. This defaults to false.
1552 =item * destructor_class
1554 The name of the method metaclass for destructors. It will be used to
1555 generate the inlined destructor. This defaults to
1556 "Class::MOP::Method::Denstructor".
1558 =item * replace_destructor
1560 This is a boolean indicating whether an existing destructor should be
1561 replaced when inlining a destructor. This defaults to false.
1565 =item B<< $metaclass->make_mutable >>
1567 Calling this method reverse the immutabilization transformation.
1571 =head2 Method Modifiers
1573 Method modifiers are hooks which allow a method to be wrapped with
1574 I<before>, I<after> and I<around> method modifiers. Every time a
1575 method is called, it's modifiers are also called.
1577 A class can modify its own methods, as well as methods defined in
1580 =head3 How method modifiers work?
1582 Method modifiers work by wrapping the original method and then
1583 replacing it in the class's symbol table. The wrappers will handle
1584 calling all the modifiers in the appropriate order and preserving the
1585 calling context for the original method.
1587 The return values of C<before> and C<after> modifiers are
1588 ignored. This is because their purpose is B<not> to filter the input
1589 and output of the primary method (this is done with an I<around>
1592 This may seem like an odd restriction to some, but doing this allows
1593 for simple code to be added at the beginning or end of a method call
1594 without altering the function of the wrapped method or placing any
1595 extra responsibility on the code of the modifier.
1597 Of course if you have more complex needs, you can use the C<around>
1598 modifier which allows you to change both the parameters passed to the
1599 wrapped method, as well as its return value.
1601 Before and around modifiers are called in last-defined-first-called
1602 order, while after modifiers are called in first-defined-first-called
1603 order. So the call tree might looks something like this:
1615 =head3 What is the performance impact?
1617 Of course there is a performance cost associated with method
1618 modifiers, but we have made every effort to make that cost directly
1619 proportional to the number of modifier features you utilize.
1621 The wrapping method does it's best to B<only> do as much work as it
1622 absolutely needs to. In order to do this we have moved some of the
1623 performance costs to set-up time, where they are easier to amortize.
1625 All this said, our benchmarks have indicated the following:
1627 simple wrapper with no modifiers 100% slower
1628 simple wrapper with simple before modifier 400% slower
1629 simple wrapper with simple after modifier 450% slower
1630 simple wrapper with simple around modifier 500-550% slower
1631 simple wrapper with all 3 modifiers 1100% slower
1633 These numbers may seem daunting, but you must remember, every feature
1634 comes with some cost. To put things in perspective, just doing a
1635 simple C<AUTOLOAD> which does nothing but extract the name of the
1636 method called and return it costs about 400% over a normal method
1641 =item B<< $metaclass->add_before_method_modifier($method_name, $code) >>
1643 This wraps the specified method with the supplied subroutine
1644 reference. The modifier will be called as a method itself, and will
1645 receive the same arguments as are passed to the method.
1647 When the modifier exits, the wrapped method will be called.
1649 The return value of the modifier will be ignored.
1651 =item B<< $metaclass->add_after_method_modifier($method_name, $code) >>
1653 This wraps the specified method with the supplied subroutine
1654 reference. The modifier will be called as a method itself, and will
1655 receive the same arguments as are passed to the method.
1657 When the wrapped methods exits, the modifier will be called.
1659 The return value of the modifier will be ignored.
1661 =item B<< $metaclass->add_around_method_modifier($method_name, $code) >>
1663 This wraps the specified method with the supplied subroutine
1666 The first argument passed to the modifier will be a subroutine
1667 reference to the wrapped method. The second argument is the object,
1668 and after that come any arguments passed when the method is called.
1670 The around modifier can choose to call the original method, as well as
1671 what arguments to pass if it does so.
1673 The return value of the modifier is what will be seen by the caller.
1677 =head2 Introspection
1681 =item B<< Class::MOP::Class->meta >>
1683 This will return a L<Class::MOP::Class> instance for this class.
1685 It should also be noted that L<Class::MOP> will actually bootstrap
1686 this module by installing a number of attribute meta-objects into its
1693 Stevan Little E<lt>stevan@iinteractive.comE<gt>
1695 =head1 COPYRIGHT AND LICENSE
1697 Copyright 2006-2009 by Infinity Interactive, Inc.
1699 L<http://www.iinteractive.com>
1701 This library is free software; you can redistribute it and/or modify
1702 it under the same terms as Perl itself.