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';
18 our $VERSION = '0.95';
19 $VERSION = eval $VERSION;
20 our $AUTHORITY = 'cpan:STEVAN';
22 use base 'Class::MOP::Module';
32 $package_name = shift;
35 $package_name = $options{package};
38 ($package_name && !ref($package_name))
39 || confess "You must pass a package name and it cannot be blessed";
41 return Class::MOP::get_metaclass_by_name($package_name)
42 || $class->_construct_class_instance(package => $package_name, @_);
45 # NOTE: (meta-circularity)
46 # this is a special form of _construct_instance
47 # (see below), which is used to construct class
48 # meta-object instances for any Class::MOP::*
49 # class. All other classes will use the more
50 # normal &construct_instance.
51 sub _construct_class_instance {
53 my $options = @_ == 1 ? $_[0] : {@_};
54 my $package_name = $options->{package};
55 (defined $package_name && $package_name)
56 || confess "You must pass a package name";
58 # return the metaclass if we have it cached,
59 # and it is still defined (it has not been
60 # reaped by DESTROY yet, which can happen
61 # annoyingly enough during global destruction)
63 if (defined(my $meta = Class::MOP::get_metaclass_by_name($package_name))) {
68 # we need to deal with the possibility
69 # of class immutability here, and then
70 # get the name of the class appropriately
72 ? ($class->is_immutable
73 ? $class->_get_mutable_metaclass_name()
77 # now create the metaclass
79 if ($class eq 'Class::MOP::Class') {
80 $meta = $class->_new($options);
84 # it is safe to use meta here because
85 # class will always be a subclass of
86 # Class::MOP::Class, which defines meta
87 $meta = $class->meta->_construct_instance($options)
90 # and check the metaclass compatibility
91 $meta->_check_metaclass_compatibility();
93 Class::MOP::store_metaclass_by_name($package_name, $meta);
96 # we need to weaken any anon classes
97 # so that they can call DESTROY properly
98 Class::MOP::weaken_metaclass($package_name) if $meta->is_anon_class;
106 return Class::MOP::Class->initialize($class)->new_object(@_)
107 if $class ne __PACKAGE__;
109 my $options = @_ == 1 ? $_[0] : {@_};
112 # inherited from Class::MOP::Package
113 'package' => $options->{package},
116 # since the following attributes will
117 # actually be loaded from the symbol
118 # table, and actually bypass the instance
119 # entirely, we can just leave these things
120 # listed here for reference, because they
121 # should not actually have a value associated
123 'namespace' => \undef,
126 # inherited from Class::MOP::Module
128 'authority' => \undef,
130 # defined in Class::MOP::Class
131 'superclasses' => \undef,
134 'attribute_metaclass' =>
135 ( $options->{'attribute_metaclass'} || 'Class::MOP::Attribute' ),
136 'method_metaclass' =>
137 ( $options->{'method_metaclass'} || 'Class::MOP::Method' ),
138 'wrapped_method_metaclass' => (
139 $options->{'wrapped_method_metaclass'}
140 || 'Class::MOP::Method::Wrapped'
142 'instance_metaclass' =>
143 ( $options->{'instance_metaclass'} || 'Class::MOP::Instance' ),
144 'immutable_trait' => (
145 $options->{'immutable_trait'}
146 || 'Class::MOP::Class::Immutable::Trait'
148 'constructor_name' => ( $options->{constructor_name} || 'new' ),
149 'constructor_class' => (
150 $options->{constructor_class} || 'Class::MOP::Method::Constructor'
152 'destructor_class' => $options->{destructor_class},
156 sub reset_package_cache_flag { (shift)->{'_package_cache_flag'} = undef }
157 sub update_package_cache_flag {
160 # we can manually update the cache number
161 # since we are actually adding the method
162 # to our cache as well. This avoids us
163 # having to regenerate the method_map.
165 $self->{'_package_cache_flag'} = Class::MOP::check_package_cache_flag($self->name);
168 sub _check_metaclass_compatibility {
171 # this is always okay ...
172 return if ref($self) eq 'Class::MOP::Class' &&
173 $self->instance_metaclass eq 'Class::MOP::Instance';
175 my @class_list = $self->linearized_isa;
176 shift @class_list; # shift off $self->name
178 foreach my $superclass_name (@class_list) {
179 my $super_meta = Class::MOP::get_metaclass_by_name($superclass_name) || next;
182 # we need to deal with the possibility
183 # of class immutability here, and then
184 # get the name of the class appropriately
186 = $super_meta->is_immutable
187 ? $super_meta->_get_mutable_metaclass_name()
190 ($self->isa($super_meta_type))
191 || confess "The metaclass of " . $self->name . " ("
192 . (ref($self)) . ")" . " is not compatible with the " .
193 "metaclass of its superclass, ".$superclass_name . " ("
194 . ($super_meta_type) . ")";
196 # we also need to check that instance metaclasses
197 # are compatibile in the same the class.
198 ($self->instance_metaclass->isa($super_meta->instance_metaclass))
199 || confess "The instance metaclass for " . $self->name . " (" . ($self->instance_metaclass) . ")" .
200 " is not compatible with the " .
201 "instance metaclass of its superclass, " . $superclass_name . " (" . ($super_meta->instance_metaclass) . ")";
209 # this should be sufficient, if you have a
210 # use case where it is not, write a test and
212 my $ANON_CLASS_SERIAL = 0;
215 # we need a sufficiently annoying prefix
216 # this should suffice for now, this is
217 # used in a couple of places below, so
218 # need to put it up here for now.
219 my $ANON_CLASS_PREFIX = 'Class::MOP::Class::__ANON__::SERIAL::';
223 no warnings 'uninitialized';
224 $self->name =~ /^$ANON_CLASS_PREFIX/o;
227 sub create_anon_class {
228 my ($class, %options) = @_;
229 my $package_name = $ANON_CLASS_PREFIX . ++$ANON_CLASS_SERIAL;
230 return $class->create($package_name, %options);
234 # this will only get called for
235 # anon-classes, all other calls
236 # are assumed to occur during
237 # global destruction and so don't
238 # really need to be handled explicitly
242 return if in_global_destruction(); # it'll happen soon anyway and this just makes things more complicated
244 no warnings 'uninitialized';
245 my $name = $self->name;
246 return unless $name =~ /^$ANON_CLASS_PREFIX/o;
247 # Moose does a weird thing where it replaces the metaclass for
248 # class when fixing metaclass incompatibility. In that case,
249 # we don't want to clean out the namespace now. We can detect
250 # that because Moose will explicitly update the singleton
251 # cache in Class::MOP.
252 my $current_meta = Class::MOP::get_metaclass_by_name($name);
253 return if $current_meta ne $self;
255 my ($serial_id) = ($name =~ /^$ANON_CLASS_PREFIX(\d+)/o);
257 @{$name . '::ISA'} = ();
258 %{$name . '::'} = ();
259 delete ${$ANON_CLASS_PREFIX}{$serial_id . '::'};
261 Class::MOP::remove_metaclass_by_name($name);
266 # creating classes with MOP ...
269 my ( $class, @args ) = @_;
271 unshift @args, 'package' if @args % 2 == 1;
273 my (%options) = @args;
274 my $package_name = $options{package};
276 (ref $options{superclasses} eq 'ARRAY')
277 || confess "You must pass an ARRAY ref of superclasses"
278 if exists $options{superclasses};
280 (ref $options{attributes} eq 'ARRAY')
281 || confess "You must pass an ARRAY ref of attributes"
282 if exists $options{attributes};
284 (ref $options{methods} eq 'HASH')
285 || confess "You must pass a HASH ref of methods"
286 if exists $options{methods};
288 my (%initialize_options) = @args;
289 delete @initialize_options{qw(
297 my $meta = $class->initialize( $package_name => %initialize_options );
299 $meta->_instantiate_module( $options{version}, $options{authority} );
302 $meta->add_method('meta' => sub {
303 $class->initialize(ref($_[0]) || $_[0]);
306 $meta->superclasses(@{$options{superclasses}})
307 if exists $options{superclasses};
309 # process attributes first, so that they can
310 # install accessors, but locally defined methods
311 # can then overwrite them. It is maybe a little odd, but
312 # I think this should be the order of things.
313 if (exists $options{attributes}) {
314 foreach my $attr (@{$options{attributes}}) {
315 $meta->add_attribute($attr);
318 if (exists $options{methods}) {
319 foreach my $method_name (keys %{$options{methods}}) {
320 $meta->add_method($method_name, $options{methods}->{$method_name});
329 # all these attribute readers will be bootstrapped
330 # away in the Class::MOP bootstrap section
332 sub _attribute_map { $_[0]->{'attributes'} }
333 sub attribute_metaclass { $_[0]->{'attribute_metaclass'} }
334 sub instance_metaclass { $_[0]->{'instance_metaclass'} }
335 sub immutable_trait { $_[0]->{'immutable_trait'} }
336 sub constructor_class { $_[0]->{'constructor_class'} }
337 sub constructor_name { $_[0]->{'constructor_name'} }
338 sub destructor_class { $_[0]->{'destructor_class'} }
340 # Instance Construction & Cloning
346 # we need to protect the integrity of the
347 # Class::MOP::Class singletons here, so we
348 # delegate this to &construct_class_instance
349 # which will deal with the singletons
350 return $class->_construct_class_instance(@_)
351 if $class->name->isa('Class::MOP::Class');
352 return $class->_construct_instance(@_);
355 sub _construct_instance {
357 my $params = @_ == 1 ? $_[0] : {@_};
358 my $meta_instance = $class->get_meta_instance();
360 # the code below is almost certainly incorrect
361 # but this is foreign inheritance, so we might
362 # have to kludge it in the end.
363 my $instance = $params->{__INSTANCE__} || $meta_instance->create_instance();
364 foreach my $attr ($class->get_all_attributes()) {
365 $attr->initialize_instance_slot($meta_instance, $instance, $params);
368 # this will only work for a HASH instance type
369 if ($class->is_anon_class) {
370 (reftype($instance) eq 'HASH')
371 || confess "Currently only HASH based instances are supported with instance of anon-classes";
373 # At some point we should make this official
374 # as a reserved slot name, but right now I am
375 # going to keep it here.
376 # my $RESERVED_MOP_SLOT = '__MOP__';
377 $instance->{'__MOP__'} = $class;
383 sub get_meta_instance {
385 $self->{'_meta_instance'} ||= $self->_create_meta_instance();
388 sub _create_meta_instance {
391 my $instance = $self->instance_metaclass->new(
392 associated_metaclass => $self,
393 attributes => [ $self->get_all_attributes() ],
396 $self->add_meta_instance_dependencies()
397 if $instance->is_dependent_on_superclasses();
404 my $instance = shift;
405 (blessed($instance) && $instance->isa($class->name))
406 || confess "You must pass an instance of the metaclass (" . (ref $class ? $class->name : $class) . "), not ($instance)";
409 # we need to protect the integrity of the
410 # Class::MOP::Class singletons here, they
411 # should not be cloned.
412 return $instance if $instance->isa('Class::MOP::Class');
413 $class->_clone_instance($instance, @_);
416 sub _clone_instance {
417 my ($class, $instance, %params) = @_;
419 || confess "You can only clone instances, ($instance) is not a blessed instance";
420 my $meta_instance = $class->get_meta_instance();
421 my $clone = $meta_instance->clone_instance($instance);
422 foreach my $attr ($class->get_all_attributes()) {
423 if ( defined( my $init_arg = $attr->init_arg ) ) {
424 if (exists $params{$init_arg}) {
425 $attr->set_value($clone, $params{$init_arg});
432 sub rebless_instance {
433 my ($self, $instance, %params) = @_;
435 my $old_metaclass = Class::MOP::class_of($instance);
437 my $old_class = $old_metaclass ? $old_metaclass->name : blessed($instance);
438 $self->name->isa($old_class)
439 || confess "You may rebless only into a subclass of ($old_class), of which (". $self->name .") isn't.";
441 $old_metaclass->rebless_instance_away($instance, $self, %params)
444 my $meta_instance = $self->get_meta_instance();
447 # we use $_[1] here because of t/306_rebless_overload.t regressions on 5.8.8
448 $meta_instance->rebless_instance_structure($_[1], $self);
450 foreach my $attr ( $self->get_all_attributes ) {
451 if ( $attr->has_value($instance) ) {
452 if ( defined( my $init_arg = $attr->init_arg ) ) {
453 $params{$init_arg} = $attr->get_value($instance)
454 unless exists $params{$init_arg};
457 $attr->set_value($instance, $attr->get_value($instance));
462 foreach my $attr ($self->get_all_attributes) {
463 $attr->initialize_instance_slot($meta_instance, $instance, \%params);
469 sub rebless_instance_away {
470 # this intentionally does nothing, it is just a hook
477 my $var_spec = { sigil => '@', type => 'ARRAY', name => 'ISA' };
480 @{$self->get_package_symbol($var_spec)} = @supers;
483 # on 5.8 and below, we need to call
484 # a method to get Perl to detect
485 # a cycle in the class hierarchy
486 my $class = $self->name;
490 # we need to check the metaclass
491 # compatibility here so that we can
492 # be sure that the superclass is
493 # not potentially creating an issues
494 # we don't know about
496 $self->_check_metaclass_compatibility();
497 $self->_superclasses_updated();
499 @{$self->get_package_symbol($var_spec)};
502 sub _superclasses_updated {
504 $self->update_meta_instance_dependencies();
509 my $super_class = $self->name;
511 return @{ $super_class->mro::get_isarev() };
514 sub direct_subclasses {
516 my $super_class = $self->name;
521 } Class::MOP::Class->initialize($_)->superclasses
526 return @{ mro::get_linear_isa( (shift)->name ) };
529 sub class_precedence_list {
531 my $name = $self->name;
533 unless (Class::MOP::IS_RUNNING_ON_5_10()) {
535 # We need to check for circular inheritance here
536 # if we are are not on 5.10, cause 5.8 detects it
537 # late. This will do nothing if all is well, and
538 # blow up otherwise. Yes, it's an ugly hack, better
539 # suggestions are welcome.
541 ($name || return)->isa('This is a test for circular inheritance')
544 # if our mro is c3, we can
545 # just grab the linear_isa
546 if (mro::get_mro($name) eq 'c3') {
547 return @{ mro::get_linear_isa($name) }
551 # we can't grab the linear_isa for dfs
552 # since it has all the duplicates
557 $self->initialize($_)->class_precedence_list()
558 } $self->superclasses()
566 my $fetch_and_prepare_method = sub {
567 my ($self, $method_name) = @_;
568 my $wrapped_metaclass = $self->wrapped_method_metaclass;
570 my $method = $self->get_method($method_name);
571 # if we dont have local ...
573 # try to find the next method
574 $method = $self->find_next_method_by_name($method_name);
575 # die if it does not exist
577 || confess "The method '$method_name' was not found in the inheritance hierarchy for " . $self->name;
578 # and now make sure to wrap it
579 # even if it is already wrapped
580 # because we need a new sub ref
581 $method = $wrapped_metaclass->wrap($method,
582 package_name => $self->name,
583 name => $method_name,
587 # now make sure we wrap it properly
588 $method = $wrapped_metaclass->wrap($method,
589 package_name => $self->name,
590 name => $method_name,
591 ) unless $method->isa($wrapped_metaclass);
593 $self->add_method($method_name => $method);
597 sub add_before_method_modifier {
598 my ($self, $method_name, $method_modifier) = @_;
599 (defined $method_name && length $method_name)
600 || confess "You must pass in a method name";
601 my $method = $fetch_and_prepare_method->($self, $method_name);
602 $method->add_before_modifier(
603 subname(':before' => $method_modifier)
607 sub add_after_method_modifier {
608 my ($self, $method_name, $method_modifier) = @_;
609 (defined $method_name && length $method_name)
610 || confess "You must pass in a method name";
611 my $method = $fetch_and_prepare_method->($self, $method_name);
612 $method->add_after_modifier(
613 subname(':after' => $method_modifier)
617 sub add_around_method_modifier {
618 my ($self, $method_name, $method_modifier) = @_;
619 (defined $method_name && length $method_name)
620 || confess "You must pass in a method name";
621 my $method = $fetch_and_prepare_method->($self, $method_name);
622 $method->add_around_modifier(
623 subname(':around' => $method_modifier)
628 # the methods above used to be named like this:
629 # ${pkg}::${method}:(before|after|around)
630 # but this proved problematic when using one modifier
631 # to wrap multiple methods (something which is likely
632 # to happen pretty regularly IMO). So instead of naming
633 # it like this, I have chosen to just name them purely
634 # with their modifier names, like so:
635 # :(before|after|around)
636 # The fact is that in a stack trace, it will be fairly
637 # evident from the context what method they are attached
638 # to, and so don't need the fully qualified name.
641 sub find_method_by_name {
642 my ($self, $method_name) = @_;
643 (defined $method_name && length $method_name)
644 || confess "You must define a method name to find";
645 foreach my $class ($self->linearized_isa) {
646 my $method = $self->initialize($class)->get_method($method_name);
647 return $method if defined $method;
652 sub get_all_methods {
656 for my $class ( reverse $self->linearized_isa ) {
657 my $meta = $self->initialize($class);
659 $methods{$_} = $meta->get_method($_)
660 for $meta->get_method_list;
663 return values %methods;
666 sub get_all_method_names {
669 return grep { !$uniq{$_}++ } map { $self->initialize($_)->get_method_list } $self->linearized_isa;
672 sub find_all_methods_by_name {
673 my ($self, $method_name) = @_;
674 (defined $method_name && length $method_name)
675 || confess "You must define a method name to find";
677 foreach my $class ($self->linearized_isa) {
678 # fetch the meta-class ...
679 my $meta = $self->initialize($class);
681 name => $method_name,
683 code => $meta->get_method($method_name)
684 } if $meta->has_method($method_name);
689 sub find_next_method_by_name {
690 my ($self, $method_name) = @_;
691 (defined $method_name && length $method_name)
692 || confess "You must define a method name to find";
693 my @cpl = $self->linearized_isa;
694 shift @cpl; # discard ourselves
695 foreach my $class (@cpl) {
696 my $method = $self->initialize($class)->get_method($method_name);
697 return $method if defined $method;
706 # either we have an attribute object already
707 # or we need to create one from the args provided
708 my $attribute = blessed($_[0]) ? $_[0] : $self->attribute_metaclass->new(@_);
709 # make sure it is derived from the correct type though
710 ($attribute->isa('Class::MOP::Attribute'))
711 || confess "Your attribute must be an instance of Class::MOP::Attribute (or a subclass)";
713 # first we attach our new attribute
714 # because it might need certain information
715 # about the class which it is attached to
716 $attribute->attach_to_class($self);
718 my $attr_name = $attribute->name;
720 # then we remove attributes of a conflicting
721 # name here so that we can properly detach
722 # the old attr object, and remove any
723 # accessors it would have generated
724 if ( $self->has_attribute($attr_name) ) {
725 $self->remove_attribute($attr_name);
727 $self->invalidate_meta_instances();
730 # get our count of previously inserted attributes and
731 # increment by one so this attribute knows its order
732 my $order = (scalar keys %{$self->_attribute_map});
733 $attribute->_set_insertion_order($order);
735 # then onto installing the new accessors
736 $self->_attribute_map->{$attr_name} = $attribute;
738 # invalidate package flag here
741 $attribute->install_accessors();
744 $self->remove_attribute($attr_name);
751 sub update_meta_instance_dependencies {
754 if ( $self->{meta_instance_dependencies} ) {
755 return $self->add_meta_instance_dependencies;
759 sub add_meta_instance_dependencies {
762 $self->remove_meta_instance_dependencies;
764 my @attrs = $self->get_all_attributes();
767 my @classes = grep { not $seen{$_->name}++ } map { $_->associated_class } @attrs;
769 foreach my $class ( @classes ) {
770 $class->add_dependent_meta_instance($self);
773 $self->{meta_instance_dependencies} = \@classes;
776 sub remove_meta_instance_dependencies {
779 if ( my $classes = delete $self->{meta_instance_dependencies} ) {
780 foreach my $class ( @$classes ) {
781 $class->remove_dependent_meta_instance($self);
791 sub add_dependent_meta_instance {
792 my ( $self, $metaclass ) = @_;
793 push @{ $self->{dependent_meta_instances} }, $metaclass;
796 sub remove_dependent_meta_instance {
797 my ( $self, $metaclass ) = @_;
798 my $name = $metaclass->name;
799 @$_ = grep { $_->name ne $name } @$_ for $self->{dependent_meta_instances};
802 sub invalidate_meta_instances {
804 $_->invalidate_meta_instance() for $self, @{ $self->{dependent_meta_instances} };
807 sub invalidate_meta_instance {
809 undef $self->{_meta_instance};
813 my ($self, $attribute_name) = @_;
814 (defined $attribute_name)
815 || confess "You must define an attribute name";
816 exists $self->_attribute_map->{$attribute_name};
820 my ($self, $attribute_name) = @_;
821 (defined $attribute_name)
822 || confess "You must define an attribute name";
823 return $self->_attribute_map->{$attribute_name}
825 # this will return undef anyway, so no need ...
826 # if $self->has_attribute($attribute_name);
830 sub remove_attribute {
831 my ($self, $attribute_name) = @_;
832 (defined $attribute_name)
833 || confess "You must define an attribute name";
834 my $removed_attribute = $self->_attribute_map->{$attribute_name};
835 return unless defined $removed_attribute;
836 delete $self->_attribute_map->{$attribute_name};
837 $self->invalidate_meta_instances();
838 $removed_attribute->remove_accessors();
839 $removed_attribute->detach_from_class();
840 return $removed_attribute;
843 sub get_attribute_list {
845 keys %{$self->_attribute_map};
848 sub get_all_attributes {
850 my %attrs = map { %{ $self->initialize($_)->_attribute_map } } reverse $self->linearized_isa;
851 return values %attrs;
854 sub find_attribute_by_name {
855 my ($self, $attr_name) = @_;
856 foreach my $class ($self->linearized_isa) {
857 # fetch the meta-class ...
858 my $meta = $self->initialize($class);
859 return $meta->get_attribute($attr_name)
860 if $meta->has_attribute($attr_name);
865 # check if we can reinitialize
869 # if any local attr is defined
870 return if $self->get_attribute_list;
872 # or any non-declared methods
873 for my $method ( map { $self->get_method($_) } $self->get_method_list ) {
874 return if $method->isa("Class::MOP::Method::Generated");
875 # FIXME do we need to enforce this too? return unless $method->isa( $self->method_metaclass );
884 sub is_immutable { 0 }
886 sub immutable_options { %{ $_[0]{__immutable}{options} || {} } }
888 sub _immutable_options {
889 my ( $self, @args ) = @_;
892 inline_accessors => 1,
893 inline_constructor => 1,
894 inline_destructor => 0,
896 immutable_trait => $self->immutable_trait,
897 constructor_name => $self->constructor_name,
898 constructor_class => $self->constructor_class,
899 destructor_class => $self->destructor_class,
905 my ( $self, @args ) = @_;
907 if ( $self->is_mutable ) {
908 $self->_initialize_immutable( $self->_immutable_options(@args) );
909 $self->_rebless_as_immutable(@args);
920 if ( $self->is_immutable ) {
921 my @args = $self->immutable_options;
922 $self->_rebless_as_mutable();
923 $self->_remove_inlined_code(@args);
924 delete $self->{__immutable};
932 sub _rebless_as_immutable {
933 my ( $self, @args ) = @_;
935 $self->{__immutable}{original_class} = ref $self;
937 bless $self => $self->_immutable_metaclass(@args);
940 sub _immutable_metaclass {
941 my ( $self, %args ) = @_;
943 if ( my $class = $args{immutable_metaclass} ) {
947 my $trait = $args{immutable_trait} = $self->immutable_trait
948 || confess "no immutable trait specified for $self";
950 my $meta = $self->meta;
951 my $meta_attr = $meta->find_attribute_by_name("immutable_trait");
955 if ( $meta_attr and $trait eq $meta_attr->default ) {
956 # if the trait is the same as the default we try and pick a
957 # predictable name for the immutable metaclass
958 $class_name = 'Class::MOP::Class::Immutable::' . ref($self);
961 $class_name = join '::', 'Class::MOP::Class::Immutable::CustomTrait',
962 $trait, 'ForMetaClass', ref($self);
966 if Class::MOP::is_class_loaded($class_name);
968 # If the metaclass is a subclass of CMOP::Class which has had
969 # metaclass roles applied (via Moose), then we want to make sure
970 # that we preserve that anonymous class (see Fey::ORM for an
971 # example of where this matters).
973 = $meta->is_immutable
974 ? $meta->_get_mutable_metaclass_name
977 my $immutable_meta = $meta_name->create(
979 superclasses => [ ref $self ],
982 Class::MOP::load_class($trait);
983 for my $meth ( Class::MOP::Class->initialize($trait)->get_all_methods ) {
984 my $meth_name = $meth->name;
986 if ( $immutable_meta->find_method_by_name( $meth_name ) ) {
987 $immutable_meta->add_around_method_modifier( $meth_name, $meth->body );
990 $immutable_meta->add_method( $meth_name, $meth->clone );
994 $immutable_meta->make_immutable(
995 inline_constructor => 0,
996 inline_accessors => 0,
1002 sub _remove_inlined_code {
1005 $self->remove_method( $_->name ) for $self->_inlined_methods;
1007 delete $self->{__immutable}{inlined_methods};
1010 sub _inlined_methods { @{ $_[0]{__immutable}{inlined_methods} || [] } }
1012 sub _add_inlined_method {
1013 my ( $self, $method ) = @_;
1015 push @{ $self->{__immutable}{inlined_methods} ||= [] }, $method;
1018 sub _initialize_immutable {
1019 my ( $self, %args ) = @_;
1021 $self->{__immutable}{options} = \%args;
1022 $self->_install_inlined_code(%args);
1025 sub _install_inlined_code {
1026 my ( $self, %args ) = @_;
1029 $self->_inline_accessors(%args) if $args{inline_accessors};
1030 $self->_inline_constructor(%args) if $args{inline_constructor};
1031 $self->_inline_destructor(%args) if $args{inline_destructor};
1034 sub _rebless_as_mutable {
1037 bless $self, $self->_get_mutable_metaclass_name;
1042 sub _inline_accessors {
1045 foreach my $attr_name ( $self->get_attribute_list ) {
1046 $self->get_attribute($attr_name)->install_accessors(1);
1050 sub _inline_constructor {
1051 my ( $self, %args ) = @_;
1053 my $name = $args{constructor_name};
1054 # A class may not even have a constructor, and that's okay.
1055 return unless defined $name;
1057 if ( $self->has_method($name) && !$args{replace_constructor} ) {
1058 my $class = $self->name;
1059 warn "Not inlining a constructor for $class since it defines"
1060 . " its own constructor.\n"
1061 . "If you are certain you don't need to inline your"
1062 . " constructor, specify inline_constructor => 0 in your"
1063 . " call to $class->meta->make_immutable\n";
1067 my $constructor_class = $args{constructor_class};
1069 Class::MOP::load_class($constructor_class);
1071 my $constructor = $constructor_class->new(
1075 package_name => $self->name,
1079 if ( $args{replace_constructor} or $constructor->can_be_inlined ) {
1080 $self->add_method( $name => $constructor );
1081 $self->_add_inlined_method($constructor);
1085 sub _inline_destructor {
1086 my ( $self, %args ) = @_;
1088 ( exists $args{destructor_class} && defined $args{destructor_class} )
1089 || confess "The 'inline_destructor' option is present, but "
1090 . "no destructor class was specified";
1092 if ( $self->has_method('DESTROY') && ! $args{replace_destructor} ) {
1093 my $class = $self->name;
1094 warn "Not inlining a destructor for $class since it defines"
1095 . " its own destructor.\n";
1099 my $destructor_class = $args{destructor_class};
1101 Class::MOP::load_class($destructor_class);
1103 return unless $destructor_class->is_needed($self);
1105 my $destructor = $destructor_class->new(
1108 package_name => $self->name,
1112 if ( $args{replace_destructor} or $destructor->can_be_inlined ) {
1113 $self->add_method( 'DESTROY' => $destructor );
1114 $self->_add_inlined_method($destructor);
1126 Class::MOP::Class - Class Meta Object
1130 # assuming that class Foo
1131 # has been defined, you can
1133 # use this for introspection ...
1135 # add a method to Foo ...
1136 Foo->meta->add_method( 'bar' => sub {...} )
1138 # get a list of all the classes searched
1139 # the method dispatcher in the correct order
1140 Foo->meta->class_precedence_list()
1142 # remove a method from Foo
1143 Foo->meta->remove_method('bar');
1145 # or use this to actually create classes ...
1147 Class::MOP::Class->create(
1150 superclasses => ['Foo'],
1152 Class::MOP::Attribute->new('$bar'),
1153 Class::MOP::Attribute->new('$baz'),
1156 calculate_bar => sub {...},
1157 construct_baz => sub {...}
1164 The Class Protocol is the largest and most complex part of the
1165 Class::MOP meta-object protocol. It controls the introspection and
1166 manipulation of Perl 5 classes, and it can create them as well. The
1167 best way to understand what this module can do is to read the
1168 documentation for each of its methods.
1172 C<Class::MOP::Class> is a subclass of L<Class::MOP::Module>.
1176 =head2 Class construction
1178 These methods all create new C<Class::MOP::Class> objects. These
1179 objects can represent existing classes or they can be used to create
1180 new classes from scratch.
1182 The metaclass object for a given class is a singleton. If you attempt
1183 to create a metaclass for the same class twice, you will just get the
1188 =item B<< Class::MOP::Class->create($package_name, %options) >>
1190 This method creates a new C<Class::MOP::Class> object with the given
1191 package name. It accepts a number of options:
1197 An optional version number for the newly created package.
1201 An optional authority for the newly created package.
1203 =item * superclasses
1205 An optional array reference of superclass names.
1209 An optional hash reference of methods for the class. The keys of the
1210 hash reference are method names and values are subroutine references.
1214 An optional array reference of L<Class::MOP::Attribute> objects.
1218 =item B<< Class::MOP::Class->create_anon_class(%options) >>
1220 This method works just like C<< Class::MOP::Class->create >> but it
1221 creates an "anonymous" class. In fact, the class does have a name, but
1222 that name is a unique name generated internally by this module.
1224 It accepts the same C<superclasses>, C<methods>, and C<attributes>
1225 parameters that C<create> accepts.
1227 Anonymous classes are destroyed once the metaclass they are attached
1228 to goes out of scope, and will be removed from Perl's internal symbol
1231 All instances of an anonymous class keep a special reference to the
1232 metaclass object, which prevents the metaclass from going out of scope
1233 while any instances exist.
1235 This only works if the instance is based on a hash reference, however.
1237 =item B<< Class::MOP::Class->initialize($package_name, %options) >>
1239 This method will initialize a C<Class::MOP::Class> object for the
1240 named package. Unlike C<create>, this method I<will not> create a new
1243 The purpose of this method is to retrieve a C<Class::MOP::Class>
1244 object for introspecting an existing class.
1246 If an existing C<Class::MOP::Class> object exists for the named
1247 package, it will be returned, and any options provided will be
1250 If the object does not yet exist, it will be created.
1252 The valid options that can be passed to this method are
1253 C<attribute_metaclass>, C<method_metaclass>,
1254 C<wrapped_method_metaclass>, and C<instance_metaclass>. These are all
1255 optional, and default to the appropriate class in the C<Class::MOP>
1260 =head2 Object instance construction and cloning
1262 These methods are all related to creating and/or cloning object
1267 =item B<< $metaclass->clone_object($instance, %params) >>
1269 This method clones an existing object instance. Any parameters you
1270 provide are will override existing attribute values in the object.
1272 This is a convenience method for cloning an object instance, then
1273 blessing it into the appropriate package.
1275 You could implement a clone method in your class, using this method:
1278 my ($self, %params) = @_;
1279 $self->meta->clone_object($self, %params);
1282 =item B<< $metaclass->rebless_instance($instance, %params) >>
1284 This method changes the class of C<$instance> to the metaclass's class.
1286 You can only rebless an instance into a subclass of its current
1287 class. If you pass any additional parameters, these will be treated
1288 like constructor parameters and used to initialize the object's
1289 attributes. Any existing attributes that are already set will be
1292 Before reblessing the instance, this method will call
1293 C<rebless_instance_away> on the instance's current metaclass. This method
1294 will be passed the instance, the new metaclass, and any parameters
1295 specified to C<rebless_instance>. By default, C<rebless_instance_away>
1296 does nothing; it is merely a hook.
1298 =item B<< $metaclass->new_object(%params) >>
1300 This method is used to create a new object of the metaclass's
1301 class. Any parameters you provide are used to initialize the
1302 instance's attributes. A special C<__INSTANCE__> key can be passed to
1303 provide an already generated instance, rather than having Class::MOP
1304 generate it for you. This is mostly useful for using Class::MOP with
1305 foreign classes which generate instances using their own constructors.
1307 =item B<< $metaclass->instance_metaclass >>
1309 Returns the class name of the instance metaclass. See
1310 L<Class::MOP::Instance> for more information on the instance
1313 =item B<< $metaclass->get_meta_instance >>
1315 Returns an instance of the C<instance_metaclass> to be used in the
1316 construction of a new instance of the class.
1320 =head2 Informational predicates
1322 These are a few predicate methods for asking information about the
1327 =item B<< $metaclass->is_anon_class >>
1329 This returns true if the class was created by calling C<<
1330 Class::MOP::Class->create_anon_class >>.
1332 =item B<< $metaclass->is_mutable >>
1334 This returns true if the class is still mutable.
1336 =item B<< $metaclass->is_immutable >>
1338 This returns true if the class has been made immutable.
1340 =item B<< $metaclass->is_pristine >>
1342 A class is I<not> pristine if it has non-inherited attributes or if it
1343 has any generated methods.
1347 =head2 Inheritance Relationships
1351 =item B<< $metaclass->superclasses(@superclasses) >>
1353 This is a read-write accessor which represents the superclass
1354 relationships of the metaclass's class.
1356 This is basically sugar around getting and setting C<@ISA>.
1358 =item B<< $metaclass->class_precedence_list >>
1360 This returns a list of all of the class's ancestor classes. The
1361 classes are returned in method dispatch order.
1363 =item B<< $metaclass->linearized_isa >>
1365 This returns a list based on C<class_precedence_list> but with all
1368 =item B<< $metaclass->subclasses >>
1370 This returns a list of all subclasses for this class, even indirect
1373 =item B<< $metaclass->direct_subclasses >>
1375 This returns a list of immediate subclasses for this class, which does not
1376 include indirect subclasses.
1380 =head2 Method introspection
1382 See L<Class::MOP::Package/Method introspection and creation> for
1383 methods that operate only on the current class. Class::MOP::Class adds
1384 introspection capabilities that take inheritance into account.
1388 =item B<< $metaclass->get_all_methods >>
1390 This will traverse the inheritance hierarchy and return a list of all
1391 the L<Class::MOP::Method> objects for this class and its parents.
1393 =item B<< $metaclass->find_method_by_name($method_name) >>
1395 This will return a L<Class::MOP::Method> for the specified
1396 C<$method_name>. If the class does not have the specified method, it
1399 Unlike C<get_method>, this method I<will> look for the named method in
1402 =item B<< $metaclass->get_all_method_names >>
1404 This will return a list of method I<names> for all of this class's
1405 methods, including inherited methods.
1407 =item B<< $metaclass->find_all_methods_by_name($method_name) >>
1409 This method looks for the named method in the class and all of its
1410 parents. It returns every matching method it finds in the inheritance
1411 tree, so it returns a list of methods.
1413 Each method is returned as a hash reference with three keys. The keys
1414 are C<name>, C<class>, and C<code>. The C<code> key has a
1415 L<Class::MOP::Method> object as its value.
1417 The list of methods is distinct.
1419 =item B<< $metaclass->find_next_method_by_name($method_name) >>
1421 This method returns the first method in any superclass matching the
1422 given name. It is effectively the method that C<SUPER::$method_name>
1427 =head2 Attribute introspection and creation
1429 Because Perl 5 does not have a core concept of attributes in classes,
1430 we can only return information about attributes which have been added
1431 via this class's methods. We cannot discover information about
1432 attributes which are defined in terms of "regular" Perl 5 methods.
1436 =item B<< $metaclass->get_attribute($attribute_name) >>
1438 This will return a L<Class::MOP::Attribute> for the specified
1439 C<$attribute_name>. If the class does not have the specified
1440 attribute, it returns C<undef>.
1442 NOTE that get_attribute does not search superclasses, for that you
1443 need to use C<find_attribute_by_name>.
1445 =item B<< $metaclass->has_attribute($attribute_name) >>
1447 Returns a boolean indicating whether or not the class defines the
1448 named attribute. It does not include attributes inherited from parent
1451 =item B<< $metaclass->get_attribute_list >>
1453 This will return a list of attributes I<names> for all attributes
1454 defined in this class.
1456 =item B<< $metaclass->get_all_attributes >>
1458 This will traverse the inheritance hierarchy and return a list of all
1459 the L<Class::MOP::Attribute> objects for this class and its parents.
1461 =item B<< $metaclass->find_attribute_by_name($attribute_name) >>
1463 This will return a L<Class::MOP::Attribute> for the specified
1464 C<$attribute_name>. If the class does not have the specified
1465 attribute, it returns C<undef>.
1467 Unlike C<get_attribute>, this attribute I<will> look for the named
1468 attribute in superclasses.
1470 =item B<< $metaclass->add_attribute(...) >>
1472 This method accepts either an existing L<Class::MOP::Attribute>
1473 object or parameters suitable for passing to that class's C<new>
1476 The attribute provided will be added to the class.
1478 Any accessor methods defined by the attribute will be added to the
1479 class when the attribute is added.
1481 If an attribute of the same name already exists, the old attribute
1482 will be removed first.
1484 =item B<< $metaclass->remove_attribute($attribute_name) >>
1486 This will remove the named attribute from the class, and
1487 L<Class::MOP::Attribute> object.
1489 Removing an attribute also removes any accessor methods defined by the
1492 However, note that removing an attribute will only affect I<future>
1493 object instances created for this class, not existing instances.
1495 =item B<< $metaclass->attribute_metaclass >>
1497 Returns the class name of the attribute metaclass for this class. By
1498 default, this is L<Class::MOP::Attribute>.
1502 =head2 Class Immutability
1504 Making a class immutable "freezes" the class definition. You can no
1505 longer call methods which alter the class, such as adding or removing
1506 methods or attributes.
1508 Making a class immutable lets us optimize the class by inlining some
1509 methods, and also allows us to optimize some methods on the metaclass
1512 After immutabilization, the metaclass object will cache most informational
1513 methods that returns information about methods or attributes. Methods which
1514 would alter the class, such as C<add_attribute> and C<add_method>, will
1515 throw an error on an immutable metaclass object.
1517 The immutabilization system in L<Moose> takes much greater advantage
1518 of the inlining features than Class::MOP itself does.
1522 =item B<< $metaclass->make_immutable(%options) >>
1524 This method will create an immutable transformer and use it to make
1525 the class and its metaclass object immutable.
1527 This method accepts the following options:
1531 =item * inline_accessors
1533 =item * inline_constructor
1535 =item * inline_destructor
1537 These are all booleans indicating whether the specified method(s)
1540 By default, accessors and the constructor are inlined, but not the
1543 =item * immutable_trait
1545 The name of a class which will be used as a parent class for the
1546 metaclass object being made immutable. This "trait" implements the
1547 post-immutability functionality of the metaclass (but not the
1548 transformation itself).
1550 This defaults to L<Class::MOP::Class::Immutable::Trait>.
1552 =item * constructor_name
1554 This is the constructor method name. This defaults to "new".
1556 =item * constructor_class
1558 The name of the method metaclass for constructors. It will be used to
1559 generate the inlined constructor. This defaults to
1560 "Class::MOP::Method::Constructor".
1562 =item * replace_constructor
1564 This is a boolean indicating whether an existing constructor should be
1565 replaced when inlining a constructor. This defaults to false.
1567 =item * destructor_class
1569 The name of the method metaclass for destructors. It will be used to
1570 generate the inlined destructor. This defaults to
1571 "Class::MOP::Method::Denstructor".
1573 =item * replace_destructor
1575 This is a boolean indicating whether an existing destructor should be
1576 replaced when inlining a destructor. This defaults to false.
1580 =item B<< $metaclass->immutable_options >>
1582 Returns a hash of the options used when making the class immutable, including
1583 both defaults and anything supplied by the user in the call to C<<
1584 $metaclass->make_immutable >>. This is useful if you need to temporarily make
1585 a class mutable and then restore immutability as it was before.
1587 =item B<< $metaclass->make_mutable >>
1589 Calling this method reverse the immutabilization transformation.
1593 =head2 Method Modifiers
1595 Method modifiers are hooks which allow a method to be wrapped with
1596 I<before>, I<after> and I<around> method modifiers. Every time a
1597 method is called, its modifiers are also called.
1599 A class can modify its own methods, as well as methods defined in
1602 =head3 How method modifiers work?
1604 Method modifiers work by wrapping the original method and then
1605 replacing it in the class's symbol table. The wrappers will handle
1606 calling all the modifiers in the appropriate order and preserving the
1607 calling context for the original method.
1609 The return values of C<before> and C<after> modifiers are
1610 ignored. This is because their purpose is B<not> to filter the input
1611 and output of the primary method (this is done with an I<around>
1614 This may seem like an odd restriction to some, but doing this allows
1615 for simple code to be added at the beginning or end of a method call
1616 without altering the function of the wrapped method or placing any
1617 extra responsibility on the code of the modifier.
1619 Of course if you have more complex needs, you can use the C<around>
1620 modifier which allows you to change both the parameters passed to the
1621 wrapped method, as well as its return value.
1623 Before and around modifiers are called in last-defined-first-called
1624 order, while after modifiers are called in first-defined-first-called
1625 order. So the call tree might looks something like this:
1637 =head3 What is the performance impact?
1639 Of course there is a performance cost associated with method
1640 modifiers, but we have made every effort to make that cost directly
1641 proportional to the number of modifier features you use.
1643 The wrapping method does its best to B<only> do as much work as it
1644 absolutely needs to. In order to do this we have moved some of the
1645 performance costs to set-up time, where they are easier to amortize.
1647 All this said, our benchmarks have indicated the following:
1649 simple wrapper with no modifiers 100% slower
1650 simple wrapper with simple before modifier 400% slower
1651 simple wrapper with simple after modifier 450% slower
1652 simple wrapper with simple around modifier 500-550% slower
1653 simple wrapper with all 3 modifiers 1100% slower
1655 These numbers may seem daunting, but you must remember, every feature
1656 comes with some cost. To put things in perspective, just doing a
1657 simple C<AUTOLOAD> which does nothing but extract the name of the
1658 method called and return it costs about 400% over a normal method
1663 =item B<< $metaclass->add_before_method_modifier($method_name, $code) >>
1665 This wraps the specified method with the supplied subroutine
1666 reference. The modifier will be called as a method itself, and will
1667 receive the same arguments as are passed to the method.
1669 When the modifier exits, the wrapped method will be called.
1671 The return value of the modifier will be ignored.
1673 =item B<< $metaclass->add_after_method_modifier($method_name, $code) >>
1675 This wraps the specified method with the supplied subroutine
1676 reference. The modifier will be called as a method itself, and will
1677 receive the same arguments as are passed to the method.
1679 When the wrapped methods exits, the modifier will be called.
1681 The return value of the modifier will be ignored.
1683 =item B<< $metaclass->add_around_method_modifier($method_name, $code) >>
1685 This wraps the specified method with the supplied subroutine
1688 The first argument passed to the modifier will be a subroutine
1689 reference to the wrapped method. The second argument is the object,
1690 and after that come any arguments passed when the method is called.
1692 The around modifier can choose to call the original method, as well as
1693 what arguments to pass if it does so.
1695 The return value of the modifier is what will be seen by the caller.
1699 =head2 Introspection
1703 =item B<< Class::MOP::Class->meta >>
1705 This will return a L<Class::MOP::Class> instance for this class.
1707 It should also be noted that L<Class::MOP> will actually bootstrap
1708 this module by installing a number of attribute meta-objects into its
1715 Stevan Little E<lt>stevan@iinteractive.comE<gt>
1717 =head1 COPYRIGHT AND LICENSE
1719 Copyright 2006-2009 by Infinity Interactive, Inc.
1721 L<http://www.iinteractive.com>
1723 This library is free software; you can redistribute it and/or modify
1724 it under the same terms as Perl itself.