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});
325 # Instance Construction & Cloning
331 # we need to protect the integrity of the
332 # Class::MOP::Class singletons here, so we
333 # delegate this to &construct_class_instance
334 # which will deal with the singletons
335 return $class->_construct_class_instance(@_)
336 if $class->name->isa('Class::MOP::Class');
337 return $class->_construct_instance(@_);
340 sub _construct_instance {
342 my $params = @_ == 1 ? $_[0] : {@_};
343 my $meta_instance = $class->get_meta_instance();
345 # the code below is almost certainly incorrect
346 # but this is foreign inheritance, so we might
347 # have to kludge it in the end.
348 my $instance = $params->{__INSTANCE__} || $meta_instance->create_instance();
349 foreach my $attr ($class->get_all_attributes()) {
350 $attr->initialize_instance_slot($meta_instance, $instance, $params);
353 # this will only work for a HASH instance type
354 if ($class->is_anon_class) {
355 (reftype($instance) eq 'HASH')
356 || confess "Currently only HASH based instances are supported with instance of anon-classes";
358 # At some point we should make this official
359 # as a reserved slot name, but right now I am
360 # going to keep it here.
361 # my $RESERVED_MOP_SLOT = '__MOP__';
362 $instance->{'__MOP__'} = $class;
368 sub get_meta_instance {
370 $self->{'_meta_instance'} ||= $self->_create_meta_instance();
373 sub _create_meta_instance {
376 my $instance = $self->instance_metaclass->new(
377 associated_metaclass => $self,
378 attributes => [ $self->get_all_attributes() ],
381 $self->add_meta_instance_dependencies()
382 if $instance->is_dependent_on_superclasses();
389 my $instance = shift;
390 (blessed($instance) && $instance->isa($class->name))
391 || confess "You must pass an instance of the metaclass (" . (ref $class ? $class->name : $class) . "), not ($instance)";
394 # we need to protect the integrity of the
395 # Class::MOP::Class singletons here, they
396 # should not be cloned.
397 return $instance if $instance->isa('Class::MOP::Class');
398 $class->_clone_instance($instance, @_);
401 sub _clone_instance {
402 my ($class, $instance, %params) = @_;
404 || confess "You can only clone instances, ($instance) is not a blessed instance";
405 my $meta_instance = $class->get_meta_instance();
406 my $clone = $meta_instance->clone_instance($instance);
407 foreach my $attr ($class->get_all_attributes()) {
408 if ( defined( my $init_arg = $attr->init_arg ) ) {
409 if (exists $params{$init_arg}) {
410 $attr->set_value($clone, $params{$init_arg});
417 sub rebless_instance {
418 my ($self, $instance, %params) = @_;
420 my $old_metaclass = Class::MOP::class_of($instance);
422 my $old_class = $old_metaclass ? $old_metaclass->name : blessed($instance);
423 $self->name->isa($old_class)
424 || confess "You may rebless only into a subclass of ($old_class), of which (". $self->name .") isn't.";
426 $old_metaclass->rebless_instance_away($instance, $self, %params)
429 my $meta_instance = $self->get_meta_instance();
432 # we use $_[1] here because of t/306_rebless_overload.t regressions on 5.8.8
433 $meta_instance->rebless_instance_structure($_[1], $self);
435 foreach my $attr ( $self->get_all_attributes ) {
436 if ( $attr->has_value($instance) ) {
437 if ( defined( my $init_arg = $attr->init_arg ) ) {
438 $params{$init_arg} = $attr->get_value($instance)
439 unless exists $params{$init_arg};
442 $attr->set_value($instance, $attr->get_value($instance));
447 foreach my $attr ($self->get_all_attributes) {
448 $attr->initialize_instance_slot($meta_instance, $instance, \%params);
454 sub rebless_instance_away {
455 # this intentionally does nothing, it is just a hook
462 my $var_spec = { sigil => '@', type => 'ARRAY', name => 'ISA' };
465 @{$self->get_package_symbol($var_spec)} = @supers;
468 # on 5.8 and below, we need to call
469 # a method to get Perl to detect
470 # a cycle in the class hierarchy
471 my $class = $self->name;
475 # we need to check the metaclass
476 # compatibility here so that we can
477 # be sure that the superclass is
478 # not potentially creating an issues
479 # we don't know about
481 $self->_check_metaclass_compatibility();
482 $self->_superclasses_updated();
484 @{$self->get_package_symbol($var_spec)};
487 sub _superclasses_updated {
489 $self->update_meta_instance_dependencies();
494 my $super_class = $self->name;
496 return @{ $super_class->mro::get_isarev() };
499 sub direct_subclasses {
501 my $super_class = $self->name;
506 } Class::MOP::Class->initialize($_)->superclasses
511 return @{ mro::get_linear_isa( (shift)->name ) };
514 sub class_precedence_list {
516 my $name = $self->name;
518 unless (Class::MOP::IS_RUNNING_ON_5_10()) {
520 # We need to check for circular inheritance here
521 # if we are are not on 5.10, cause 5.8 detects it
522 # late. This will do nothing if all is well, and
523 # blow up otherwise. Yes, it's an ugly hack, better
524 # suggestions are welcome.
526 ($name || return)->isa('This is a test for circular inheritance')
529 # if our mro is c3, we can
530 # just grab the linear_isa
531 if (mro::get_mro($name) eq 'c3') {
532 return @{ mro::get_linear_isa($name) }
536 # we can't grab the linear_isa for dfs
537 # since it has all the duplicates
542 $self->initialize($_)->class_precedence_list()
543 } $self->superclasses()
551 my $fetch_and_prepare_method = sub {
552 my ($self, $method_name) = @_;
553 my $wrapped_metaclass = $self->wrapped_method_metaclass;
555 my $method = $self->get_method($method_name);
556 # if we dont have local ...
558 # try to find the next method
559 $method = $self->find_next_method_by_name($method_name);
560 # die if it does not exist
562 || confess "The method '$method_name' was not found in the inheritance hierarchy for " . $self->name;
563 # and now make sure to wrap it
564 # even if it is already wrapped
565 # because we need a new sub ref
566 $method = $wrapped_metaclass->wrap($method,
567 package_name => $self->name,
568 name => $method_name,
572 # now make sure we wrap it properly
573 $method = $wrapped_metaclass->wrap($method,
574 package_name => $self->name,
575 name => $method_name,
576 ) unless $method->isa($wrapped_metaclass);
578 $self->add_method($method_name => $method);
582 sub add_before_method_modifier {
583 my ($self, $method_name, $method_modifier) = @_;
584 (defined $method_name && $method_name)
585 || confess "You must pass in a method name";
586 my $method = $fetch_and_prepare_method->($self, $method_name);
587 $method->add_before_modifier(
588 subname(':before' => $method_modifier)
592 sub add_after_method_modifier {
593 my ($self, $method_name, $method_modifier) = @_;
594 (defined $method_name && $method_name)
595 || confess "You must pass in a method name";
596 my $method = $fetch_and_prepare_method->($self, $method_name);
597 $method->add_after_modifier(
598 subname(':after' => $method_modifier)
602 sub add_around_method_modifier {
603 my ($self, $method_name, $method_modifier) = @_;
604 (defined $method_name && $method_name)
605 || confess "You must pass in a method name";
606 my $method = $fetch_and_prepare_method->($self, $method_name);
607 $method->add_around_modifier(
608 subname(':around' => $method_modifier)
613 # the methods above used to be named like this:
614 # ${pkg}::${method}:(before|after|around)
615 # but this proved problematic when using one modifier
616 # to wrap multiple methods (something which is likely
617 # to happen pretty regularly IMO). So instead of naming
618 # it like this, I have chosen to just name them purely
619 # with their modifier names, like so:
620 # :(before|after|around)
621 # The fact is that in a stack trace, it will be fairly
622 # evident from the context what method they are attached
623 # to, and so don't need the fully qualified name.
626 sub find_method_by_name {
627 my ($self, $method_name) = @_;
628 (defined $method_name && $method_name)
629 || confess "You must define a method name to find";
630 foreach my $class ($self->linearized_isa) {
631 my $method = $self->initialize($class)->get_method($method_name);
632 return $method if defined $method;
637 sub get_all_methods {
639 my %methods = map { %{ $self->initialize($_)->get_method_map } } reverse $self->linearized_isa;
640 return values %methods;
643 sub get_all_method_names {
646 return grep { !$uniq{$_}++ } map { $self->initialize($_)->get_method_list } $self->linearized_isa;
649 sub find_all_methods_by_name {
650 my ($self, $method_name) = @_;
651 (defined $method_name && $method_name)
652 || confess "You must define a method name to find";
654 foreach my $class ($self->linearized_isa) {
655 # fetch the meta-class ...
656 my $meta = $self->initialize($class);
658 name => $method_name,
660 code => $meta->get_method($method_name)
661 } if $meta->has_method($method_name);
666 sub find_next_method_by_name {
667 my ($self, $method_name) = @_;
668 (defined $method_name && $method_name)
669 || confess "You must define a method name to find";
670 my @cpl = $self->linearized_isa;
671 shift @cpl; # discard ourselves
672 foreach my $class (@cpl) {
673 my $method = $self->initialize($class)->get_method($method_name);
674 return $method if defined $method;
683 # either we have an attribute object already
684 # or we need to create one from the args provided
685 my $attribute = blessed($_[0]) ? $_[0] : $self->attribute_metaclass->new(@_);
686 # make sure it is derived from the correct type though
687 ($attribute->isa('Class::MOP::Attribute'))
688 || confess "Your attribute must be an instance of Class::MOP::Attribute (or a subclass)";
690 # first we attach our new attribute
691 # because it might need certain information
692 # about the class which it is attached to
693 $attribute->attach_to_class($self);
695 my $attr_name = $attribute->name;
697 # then we remove attributes of a conflicting
698 # name here so that we can properly detach
699 # the old attr object, and remove any
700 # accessors it would have generated
701 if ( $self->has_attribute($attr_name) ) {
702 $self->remove_attribute($attr_name);
704 $self->invalidate_meta_instances();
707 # get our count of previously inserted attributes and
708 # increment by one so this attribute knows its order
709 my $order = (scalar keys %{$self->get_attribute_map});
710 $attribute->_set_insertion_order($order);
712 # then onto installing the new accessors
713 $self->get_attribute_map->{$attr_name} = $attribute;
715 # invalidate package flag here
719 eval { $attribute->install_accessors() };
723 $self->remove_attribute($attr_name);
730 sub update_meta_instance_dependencies {
733 if ( $self->{meta_instance_dependencies} ) {
734 return $self->add_meta_instance_dependencies;
738 sub add_meta_instance_dependencies {
741 $self->remove_meta_instance_dependencies;
743 my @attrs = $self->get_all_attributes();
746 my @classes = grep { not $seen{$_->name}++ } map { $_->associated_class } @attrs;
748 foreach my $class ( @classes ) {
749 $class->add_dependent_meta_instance($self);
752 $self->{meta_instance_dependencies} = \@classes;
755 sub remove_meta_instance_dependencies {
758 if ( my $classes = delete $self->{meta_instance_dependencies} ) {
759 foreach my $class ( @$classes ) {
760 $class->remove_dependent_meta_instance($self);
770 sub add_dependent_meta_instance {
771 my ( $self, $metaclass ) = @_;
772 push @{ $self->{dependent_meta_instances} }, $metaclass;
775 sub remove_dependent_meta_instance {
776 my ( $self, $metaclass ) = @_;
777 my $name = $metaclass->name;
778 @$_ = grep { $_->name ne $name } @$_ for $self->{dependent_meta_instances};
781 sub invalidate_meta_instances {
783 $_->invalidate_meta_instance() for $self, @{ $self->{dependent_meta_instances} };
786 sub invalidate_meta_instance {
788 undef $self->{_meta_instance};
792 my ($self, $attribute_name) = @_;
793 (defined $attribute_name)
794 || confess "You must define an attribute name";
795 exists $self->get_attribute_map->{$attribute_name};
799 my ($self, $attribute_name) = @_;
800 (defined $attribute_name)
801 || confess "You must define an attribute name";
802 return $self->get_attribute_map->{$attribute_name}
804 # this will return undef anyway, so no need ...
805 # if $self->has_attribute($attribute_name);
809 sub remove_attribute {
810 my ($self, $attribute_name) = @_;
811 (defined $attribute_name)
812 || confess "You must define an attribute name";
813 my $removed_attribute = $self->get_attribute_map->{$attribute_name};
814 return unless defined $removed_attribute;
815 delete $self->get_attribute_map->{$attribute_name};
816 $self->invalidate_meta_instances();
817 $removed_attribute->remove_accessors();
818 $removed_attribute->detach_from_class();
819 return $removed_attribute;
822 sub get_attribute_list {
824 keys %{$self->get_attribute_map};
827 sub get_all_attributes {
829 my %attrs = map { %{ $self->initialize($_)->get_attribute_map } } reverse $self->linearized_isa;
830 return values %attrs;
833 sub find_attribute_by_name {
834 my ($self, $attr_name) = @_;
835 foreach my $class ($self->linearized_isa) {
836 # fetch the meta-class ...
837 my $meta = $self->initialize($class);
838 return $meta->get_attribute($attr_name)
839 if $meta->has_attribute($attr_name);
844 # check if we can reinitialize
848 # if any local attr is defined
849 return if $self->get_attribute_list;
851 # or any non-declared methods
852 if ( my @methods = values %{ $self->get_method_map } ) {
853 my $metaclass = $self->method_metaclass;
854 foreach my $method ( @methods ) {
855 return if $method->isa("Class::MOP::Method::Generated");
856 # FIXME do we need to enforce this too? return unless $method->isa($metaclass);
866 sub is_immutable { 0 }
868 sub _immutable_options {
869 my ( $self, @args ) = @_;
872 inline_constructor => 1,
873 inline_destructor => 0,
875 immutable_trait => $self->immutable_trait,
876 constructor_name => $self->constructor_name,
877 constructor_class => $self->constructor_class,
878 destructor_class => $self->destructor_class,
884 my ( $self, @args ) = @_;
886 if ( $self->is_mutable ) {
887 $self->_initialize_immutable( $self->_immutable_options(@args) );
888 $self->_rebless_as_immutable(@args);
899 if ( $self->is_immutable ) {
900 my @args = $self->immutable_options;
901 $self->_rebless_as_mutable();
902 $self->_remove_inlined_code(@args);
903 delete $self->{__immutable};
911 sub _rebless_as_immutable {
912 my ( $self, @args ) = @_;
914 $self->{__immutable}{original_class} = ref $self;
916 bless $self => $self->_immutable_metaclass(@args);
919 sub _immutable_metaclass {
920 my ( $self, %args ) = @_;
922 if ( my $class = $args{immutable_metaclass} ) {
926 my $trait = $args{immutable_trait} = $self->immutable_trait
927 || confess "no immutable trait specified for $self";
929 my $meta = $self->meta;
930 my $meta_attr = $meta->find_attribute_by_name("immutable_trait");
934 if ( $meta_attr and $trait eq $meta_attr->default ) {
935 # if the trait is the same as the default we try and pick a
936 # predictable name for the immutable metaclass
937 $class_name = 'Class::MOP::Class::Immutable::' . ref($self);
940 $class_name = join '::', 'Class::MOP::Class::Immutable::CustomTrait',
941 $trait, 'ForMetaClass', ref($self);
945 if Class::MOP::is_class_loaded($class_name);
947 # If the metaclass is a subclass of CMOP::Class which has had
948 # metaclass roles applied (via Moose), then we want to make sure
949 # that we preserve that anonymous class (see Fey::ORM for an
950 # example of where this matters).
952 = $meta->is_immutable
953 ? $meta->get_mutable_metaclass_name
956 my $immutable_meta = $meta_name->create(
958 superclasses => [ ref $self ],
961 Class::MOP::load_class($trait);
962 for my $meth ( Class::MOP::Class->initialize($trait)->get_all_methods ) {
963 my $meth_name = $meth->name;
965 if ( $immutable_meta->find_method_by_name( $meth_name ) ) {
966 $immutable_meta->add_around_method_modifier( $meth_name, $meth->body );
969 $immutable_meta->add_method( $meth_name, $meth->clone );
973 $immutable_meta->make_immutable(
974 inline_constructor => 0,
980 sub _remove_inlined_code {
983 $self->remove_method( $_->name ) for $self->_inlined_methods;
985 delete $self->{__immutable}{inlined_methods};
988 sub _inlined_methods { @{ $_[0]{__immutable}{inlined_methods} || [] } }
990 sub _add_inlined_method {
991 my ( $self, $method ) = @_;
993 push @{ $self->{__immutable}{inlined_methods} ||= [] }, $method;
996 sub _initialize_immutable {
997 my ( $self, %args ) = @_;
999 $self->{__immutable}{options} = \%args;
1000 $self->_install_inlined_code(%args);
1003 sub _install_inlined_code {
1004 my ( $self, %args ) = @_;
1007 $self->_inline_constructor(%args) if $args{inline_constructor};
1008 $self->_inline_destructor(%args) if $args{inline_destructor};
1011 sub _rebless_as_mutable {
1014 bless $self, $self->get_mutable_metaclass_name;
1019 sub _inline_accessors {
1020 Carp::cluck("The _inline_accessors method is deprecated and will be removed in a future release.\n");
1024 foreach my $attr_name ( $self->get_attribute_list ) {
1025 $self->get_attribute($attr_name)->install_accessors(1);
1029 sub _inline_constructor {
1030 my ( $self, %args ) = @_;
1032 my $name = $args{constructor_name};
1034 if ( $self->has_method($name) && !$args{replace_constructor} ) {
1035 my $class = $self->name;
1036 warn "Not inlining a constructor for $class since it defines"
1037 . " its own constructor.\n"
1038 . "If you are certain you don't need to inline your"
1039 . " constructor, specify inline_constructor => 0 in your"
1040 . " call to $class->meta->make_immutable\n";
1044 my $constructor_class = $args{constructor_class};
1046 Class::MOP::load_class($constructor_class);
1048 my $constructor = $constructor_class->new(
1052 package_name => $self->name,
1056 if ( $args{replace_constructor} or $constructor->can_be_inlined ) {
1057 $self->add_method( $name => $constructor );
1058 $self->_add_inlined_method($constructor);
1062 sub _inline_destructor {
1063 my ( $self, %args ) = @_;
1065 ( exists $args{destructor_class} && defined $args{destructor_class} )
1066 || confess "The 'inline_destructor' option is present, but "
1067 . "no destructor class was specified";
1069 if ( $self->has_method('DESTROY') && ! $args{replace_destructor} ) {
1070 my $class = $self->name;
1071 warn "Not inlining a destructor for $class since it defines"
1072 . " its own destructor.\n";
1076 my $destructor_class = $args{destructor_class};
1078 Class::MOP::load_class($destructor_class);
1080 return unless $destructor_class->is_needed($self);
1082 my $destructor = $destructor_class->new(
1085 package_name => $self->name,
1089 if ( $args{replace_destructor} or $destructor->can_be_inlined ) {
1090 $self->add_method( 'DESTROY' => $destructor );
1091 $self->_add_inlined_method($destructor);
1103 Class::MOP::Class - Class Meta Object
1107 # assuming that class Foo
1108 # has been defined, you can
1110 # use this for introspection ...
1112 # add a method to Foo ...
1113 Foo->meta->add_method( 'bar' => sub {...} )
1115 # get a list of all the classes searched
1116 # the method dispatcher in the correct order
1117 Foo->meta->class_precedence_list()
1119 # remove a method from Foo
1120 Foo->meta->remove_method('bar');
1122 # or use this to actually create classes ...
1124 Class::MOP::Class->create(
1127 superclasses => ['Foo'],
1129 Class::MOP::Attribute->new('$bar'),
1130 Class::MOP::Attribute->new('$baz'),
1133 calculate_bar => sub {...},
1134 construct_baz => sub {...}
1141 The Class Protocol is the largest and most complex part of the
1142 Class::MOP meta-object protocol. It controls the introspection and
1143 manipulation of Perl 5 classes, and it can create them as well. The
1144 best way to understand what this module can do, is to read the
1145 documentation for each of its methods.
1149 C<Class::MOP::Class> is a subclass of L<Class::MOP::Module>.
1153 =head2 Class construction
1155 These methods all create new C<Class::MOP::Class> objects. These
1156 objects can represent existing classes, or they can be used to create
1157 new classes from scratch.
1159 The metaclass object for a given class is a singleton. If you attempt
1160 to create a metaclass for the same class twice, you will just get the
1165 =item B<< Class::MOP::Class->create($package_name, %options) >>
1167 This method creates a new C<Class::MOP::Class> object with the given
1168 package name. It accepts a number of options.
1174 An optional version number for the newly created package.
1178 An optional authority for the newly created package.
1180 =item * superclasses
1182 An optional array reference of superclass names.
1186 An optional hash reference of methods for the class. The keys of the
1187 hash reference are method names, and values are subroutine references.
1191 An optional array reference of L<Class::MOP::Attribute> objects.
1195 =item B<< Class::MOP::Class->create_anon_class(%options) >>
1197 This method works just like C<< Class::MOP::Class->create >> but it
1198 creates an "anonymous" class. In fact, the class does have a name, but
1199 that name is a unique name generated internally by this module.
1201 It accepts the same C<superclasses>, C<methods>, and C<attributes>
1202 parameters that C<create> accepts.
1204 Anonymous classes are destroyed once the metaclass they are attached
1205 to goes out of scope, and will be removed from Perl's internal symbol
1208 All instances of an anonymous class keep a special reference to the
1209 metaclass object, which prevents the metaclass from going out of scope
1210 while any instances exist.
1212 This only works if the instance if based on a hash reference, however.
1214 =item B<< Class::MOP::Class->initialize($package_name, %options) >>
1216 This method will initialize a C<Class::MOP::Class> object for the
1217 named package. Unlike C<create>, this method I<will not> create a new
1220 The purpose of this method is to retrieve a C<Class::MOP::Class>
1221 object for introspecting an existing class.
1223 If an existing C<Class::MOP::Class> object exists for the named
1224 package, it will be returned, and any options provided will be
1227 If the object does not yet exist, it will be created.
1229 The valid options that can be passed to this method are
1230 C<attribute_metaclass>, C<method_metaclass>,
1231 C<wrapped_method_metaclass>, and C<instance_metaclass>. These are all
1232 optional, and default to the appropriate class in the C<Class::MOP>
1237 =head2 Object instance construction and cloning
1239 These methods are all related to creating and/or cloning object
1244 =item B<< $metaclass->clone_object($instance, %params) >>
1246 This method clones an existing object instance. Any parameters you
1247 provide are will override existing attribute values in the object.
1249 This is a convenience method for cloning an object instance, then
1250 blessing it into the appropriate package.
1252 You could implement a clone method in your class, using this method:
1255 my ($self, %params) = @_;
1256 $self->meta->clone_object($self, %params);
1259 =item B<< $metaclass->rebless_instance($instance, %params) >>
1261 This method changes the class of C<$instance> to the metaclass's class.
1263 You can only rebless an instance into a subclass of its current
1264 class. If you pass any additional parameters, these will be treated
1265 like constructor parameters and used to initialize the object's
1266 attributes. Any existing attributes that are already set will be
1269 Before reblessing the instance, this method will call
1270 C<rebless_instance_away> on the instance's current metaclass. This method
1271 will be passed the instance, the new metaclass, and any parameters
1272 specified to C<rebless_instance>. By default, C<rebless_instance_away>
1273 does nothing; it is merely a hook.
1275 =item B<< $metaclass->new_object(%params) >>
1277 This method is used to create a new object of the metaclass's
1278 class. Any parameters you provide are used to initialize the
1279 instance's attributes. A special C<__INSTANCE__> key can be passed to
1280 provide an already generated instance, rather than having Class::MOP
1281 generate it for you. This is mostly useful for using Class::MOP with
1282 foreign classes, which generally generate instances using their own
1285 =item B<< $metaclass->instance_metaclass >>
1287 Returns the class name of the instance metaclass, see
1288 L<Class::MOP::Instance> for more information on the instance
1291 =item B<< $metaclass->get_meta_instance >>
1293 Returns an instance of the C<instance_metaclass> to be used in the
1294 construction of a new instance of the class.
1298 =head2 Informational predicates
1300 These are a few predicate methods for asking information about the
1305 =item B<< $metaclass->is_anon_class >>
1307 This returns true if the class was created by calling C<<
1308 Class::MOP::Class->create_anon_class >>.
1310 =item B<< $metaclass->is_mutable >>
1312 This returns true if the class is still mutable.
1314 =item B<< $metaclass->is_immutable >>
1316 This returns true if the class has been made immutable.
1318 =item B<< $metaclass->is_pristine >>
1320 A class is I<not> pristine if it has non-inherited attributes or if it
1321 has any generated methods.
1325 =head2 Inheritance Relationships
1329 =item B<< $metaclass->superclasses(@superclasses) >>
1331 This is a read-write accessor which represents the superclass
1332 relationships of the metaclass's class.
1334 This is basically sugar around getting and setting C<@ISA>.
1336 =item B<< $metaclass->class_precedence_list >>
1338 This returns a list of all of the class's ancestor classes. The
1339 classes are returned in method dispatch order.
1341 =item B<< $metaclass->linearized_isa >>
1343 This returns a list based on C<class_precedence_list> but with all
1346 =item B<< $metaclass->subclasses >>
1348 This returns a list of all subclasses for this class, even indirect
1351 =item B<< $metaclass->direct_subclasses >>
1353 This returns a list of immediate subclasses for this class, which does not
1354 include indirect subclasses.
1358 =head2 Method introspection
1360 See L<Class::MOP::Package/Method introspection and creation> for
1361 methods that operate only on the current class. Class::MOP::Class adds
1362 introspection capabilities that take inheritance into account.
1366 =item B<< $metaclass->get_all_methods >>
1368 This will traverse the inheritance hierarchy and return a list of all
1369 the L<Class::MOP::Method> objects for this class and its parents.
1371 =item B<< $metaclass->find_method_by_name($method_name) >>
1373 This will return a L<Class::MOP::Method> for the specified
1374 C<$method_name>. If the class does not have the specified method, it
1377 Unlike C<get_method>, this method I<will> look for the named method in
1380 =item B<< $metaclass->get_all_method_names >>
1382 This will return a list of method I<names> for all of this class's
1383 methods, including inherited methods.
1385 =item B<< $metaclass->find_all_methods_by_name($method_name) >>
1387 This method looks for the named method in the class and all of its
1388 parents. It returns every matching method it finds in the inheritance
1389 tree, so it returns a list of methods.
1391 Each method is returned as a hash reference with three keys. The keys
1392 are C<name>, C<class>, and C<code>. The C<code> key has a
1393 L<Class::MOP::Method> object as its value.
1395 The list of methods is distinct.
1397 =item B<< $metaclass->find_next_method_by_name($method_name) >>
1399 This method returns the first method in any superclass matching the
1400 given name. It is effectively the method that C<SUPER::$method_name>
1405 =head2 Attribute introspection and creation
1407 Because Perl 5 does not have a core concept of attributes in classes,
1408 we can only return information about attributes which have been added
1409 via this class's methods. We cannot discover information about
1410 attributes which are defined in terms of "regular" Perl 5 methods.
1414 =item B<< $metaclass->get_attribute($attribute_name) >>
1416 This will return a L<Class::MOP::Attribute> for the specified
1417 C<$attribute_name>. If the class does not have the specified
1418 attribute, it returns C<undef>.
1420 NOTE that get_attribute does not search superclasses, for that you
1421 need to use C<find_attribute_by_name>.
1423 =item B<< $metaclass->has_attribute($attribute_name) >>
1425 Returns a boolean indicating whether or not the class defines the
1426 named attribute. It does not include attributes inherited from parent
1429 =item B<< $metaclass->get_attribute_map >>
1431 Returns a hash reference representing the attributes defined in this
1432 class. The keys are attribute names and the values are
1433 L<Class::MOP::Attribute> objects.
1435 =item B<< $metaclass->get_attribute_list >>
1437 This will return a list of attributes I<names> for all attributes
1438 defined in this class.
1440 =item B<< $metaclass->get_all_attributes >>
1442 This will traverse the inheritance hierarchy and return a list of all
1443 the L<Class::MOP::Attribute> objects for this class and its parents.
1445 =item B<< $metaclass->find_attribute_by_name($attribute_name) >>
1447 This will return a L<Class::MOP::Attribute> for the specified
1448 C<$attribute_name>. If the class does not have the specified
1449 attribute, it returns C<undef>
1451 Unlike C<get_attribute>, this attribute I<will> look for the named
1452 attribute in superclasses.
1454 =item B<< $metaclass->add_attribute(...) >>
1456 This method accepts either an existing L<Class::MOP::Attribute>
1457 object, or parameters suitable for passing to that class's C<new>
1460 The attribute provided will be added to the class.
1462 Any accessor methods defined by the attribute will be added to the
1463 class when the attribute is added.
1465 If an attribute of the same name already exists, the old attribute
1466 will be removed first.
1468 =item B<< $metaclass->remove_attribute($attribute_name) >>
1470 This will remove the named attribute from the class, and
1471 L<Class::MOP::Attribute> object.
1473 Removing an attribute also removes any accessor methods defined by the
1476 However, note that removing an attribute will only affect I<future>
1477 object instances created for this class, not existing instances.
1479 =item B<< $metaclass->attribute_metaclass >>
1481 Returns the class name of the attribute metaclass for this class. By
1482 default, this is L<Class::MOP::Attribute>.
1486 =head2 Class Immutability
1488 Making a class immutable "freezes" the class definition. You can no
1489 longer call methods which alter the class, such as adding or removing
1490 methods or attributes.
1492 Making a class immutable lets us optimize the class by inlining some
1493 methods, and also allows us to optimize some methods on the metaclass
1496 After immutabilization, the metaclass object will cache most
1497 informational methods such as C<get_method_map> and
1498 C<get_all_attributes>. Methods which would alter the class, such as
1499 C<add_attribute>, C<add_method>, and so on will throw an error on an
1500 immutable metaclass object.
1502 The immutabilization system in L<Moose> takes much greater advantage
1503 of the inlining features than Class::MOP itself does.
1507 =item B<< $metaclass->make_immutable(%options) >>
1509 This method will create an immutable transformer and uses it to make
1510 the class and its metaclass object immutable.
1512 This method accepts the following options:
1516 =item * inline_constructor
1518 =item * inline_destructor
1520 These are all booleans indicating whether the specified method(s)
1523 By default, accessors and the constructor are inlined, but not the
1526 =item * immutable_trait
1528 The name of a class which will be used as a parent class for the
1529 metaclass object being made immutable. This "trait" implements the
1530 post-immutability functionality of the metaclass (but not the
1531 transformation itself).
1533 This defaults to L<Class::MOP::Class::Immutable::Trait>.
1535 =item * constructor_name
1537 This is the constructor method name. This defaults to "new".
1539 =item * constructor_class
1541 The name of the method metaclass for constructors. It will be used to
1542 generate the inlined constructor. This defaults to
1543 "Class::MOP::Method::Constructor".
1545 =item * replace_constructor
1547 This is a boolean indicating whether an existing constructor should be
1548 replaced when inlining a constructor. This defaults to false.
1550 =item * destructor_class
1552 The name of the method metaclass for destructors. It will be used to
1553 generate the inlined destructor. This defaults to
1554 "Class::MOP::Method::Denstructor".
1556 =item * replace_destructor
1558 This is a boolean indicating whether an existing destructor should be
1559 replaced when inlining a destructor. This defaults to false.
1563 =item B<< $metaclass->make_mutable >>
1565 Calling this method reverse the immutabilization transformation.
1569 =head2 Method Modifiers
1571 Method modifiers are hooks which allow a method to be wrapped with
1572 I<before>, I<after> and I<around> method modifiers. Every time a
1573 method is called, it's modifiers are also called.
1575 A class can modify its own methods, as well as methods defined in
1578 =head3 How method modifiers work?
1580 Method modifiers work by wrapping the original method and then
1581 replacing it in the class's symbol table. The wrappers will handle
1582 calling all the modifiers in the appropriate order and preserving the
1583 calling context for the original method.
1585 The return values of C<before> and C<after> modifiers are
1586 ignored. This is because their purpose is B<not> to filter the input
1587 and output of the primary method (this is done with an I<around>
1590 This may seem like an odd restriction to some, but doing this allows
1591 for simple code to be added at the beginning or end of a method call
1592 without altering the function of the wrapped method or placing any
1593 extra responsibility on the code of the modifier.
1595 Of course if you have more complex needs, you can use the C<around>
1596 modifier which allows you to change both the parameters passed to the
1597 wrapped method, as well as its return value.
1599 Before and around modifiers are called in last-defined-first-called
1600 order, while after modifiers are called in first-defined-first-called
1601 order. So the call tree might looks something like this:
1613 =head3 What is the performance impact?
1615 Of course there is a performance cost associated with method
1616 modifiers, but we have made every effort to make that cost directly
1617 proportional to the number of modifier features you utilize.
1619 The wrapping method does it's best to B<only> do as much work as it
1620 absolutely needs to. In order to do this we have moved some of the
1621 performance costs to set-up time, where they are easier to amortize.
1623 All this said, our benchmarks have indicated the following:
1625 simple wrapper with no modifiers 100% slower
1626 simple wrapper with simple before modifier 400% slower
1627 simple wrapper with simple after modifier 450% slower
1628 simple wrapper with simple around modifier 500-550% slower
1629 simple wrapper with all 3 modifiers 1100% slower
1631 These numbers may seem daunting, but you must remember, every feature
1632 comes with some cost. To put things in perspective, just doing a
1633 simple C<AUTOLOAD> which does nothing but extract the name of the
1634 method called and return it costs about 400% over a normal method
1639 =item B<< $metaclass->add_before_method_modifier($method_name, $code) >>
1641 This wraps the specified method with the supplied subroutine
1642 reference. The modifier will be called as a method itself, and will
1643 receive the same arguments as are passed to the method.
1645 When the modifier exits, the wrapped method will be called.
1647 The return value of the modifier will be ignored.
1649 =item B<< $metaclass->add_after_method_modifier($method_name, $code) >>
1651 This wraps the specified method with the supplied subroutine
1652 reference. The modifier will be called as a method itself, and will
1653 receive the same arguments as are passed to the method.
1655 When the wrapped methods exits, the modifier will be called.
1657 The return value of the modifier will be ignored.
1659 =item B<< $metaclass->add_around_method_modifier($method_name, $code) >>
1661 This wraps the specified method with the supplied subroutine
1664 The first argument passed to the modifier will be a subroutine
1665 reference to the wrapped method. The second argument is the object,
1666 and after that come any arguments passed when the method is called.
1668 The around modifier can choose to call the original method, as well as
1669 what arguments to pass if it does so.
1671 The return value of the modifier is what will be seen by the caller.
1675 =head2 Introspection
1679 =item B<< Class::MOP::Class->meta >>
1681 This will return a L<Class::MOP::Class> instance for this class.
1683 It should also be noted that L<Class::MOP> will actually bootstrap
1684 this module by installing a number of attribute meta-objects into its
1691 Stevan Little E<lt>stevan@iinteractive.comE<gt>
1693 =head1 COPYRIGHT AND LICENSE
1695 Copyright 2006-2009 by Infinity Interactive, Inc.
1697 L<http://www.iinteractive.com>
1699 This library is free software; you can redistribute it and/or modify
1700 it under the same terms as Perl itself.