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 sub construct_class_instance {
45 Carp::cluck('The construct_class_instance method has been made private.'
46 . " The public version is deprecated and will be removed in a future release.\n");
47 shift->_construct_class_instance(@_);
50 # NOTE: (meta-circularity)
51 # this is a special form of _construct_instance
52 # (see below), which is used to construct class
53 # meta-object instances for any Class::MOP::*
54 # class. All other classes will use the more
55 # normal &construct_instance.
56 sub _construct_class_instance {
58 my $options = @_ == 1 ? $_[0] : {@_};
59 my $package_name = $options->{package};
60 (defined $package_name && $package_name)
61 || confess "You must pass a package name";
63 # return the metaclass if we have it cached,
64 # and it is still defined (it has not been
65 # reaped by DESTROY yet, which can happen
66 # annoyingly enough during global destruction)
68 if (defined(my $meta = Class::MOP::get_metaclass_by_name($package_name))) {
73 # we need to deal with the possibility
74 # of class immutability here, and then
75 # get the name of the class appropriately
77 ? ($class->is_immutable
78 ? $class->get_mutable_metaclass_name()
82 # now create the metaclass
84 if ($class eq 'Class::MOP::Class') {
85 $meta = $class->_new($options);
89 # it is safe to use meta here because
90 # class will always be a subclass of
91 # Class::MOP::Class, which defines meta
92 $meta = $class->meta->_construct_instance($options)
95 # and check the metaclass compatibility
96 $meta->_check_metaclass_compatibility();
98 Class::MOP::store_metaclass_by_name($package_name, $meta);
101 # we need to weaken any anon classes
102 # so that they can call DESTROY properly
103 Class::MOP::weaken_metaclass($package_name) if $meta->is_anon_class;
111 return Class::MOP::Class->initialize($class)->new_object(@_)
112 if $class ne __PACKAGE__;
114 my $options = @_ == 1 ? $_[0] : {@_};
117 # inherited from Class::MOP::Package
118 'package' => $options->{package},
121 # since the following attributes will
122 # actually be loaded from the symbol
123 # table, and actually bypass the instance
124 # entirely, we can just leave these things
125 # listed here for reference, because they
126 # should not actually have a value associated
128 'namespace' => \undef,
130 # inherited from Class::MOP::Module
132 'authority' => \undef,
134 # defined in Class::MOP::Class
135 'superclasses' => \undef,
139 'attribute_metaclass' =>
140 ( $options->{'attribute_metaclass'} || 'Class::MOP::Attribute' ),
141 'method_metaclass' =>
142 ( $options->{'method_metaclass'} || 'Class::MOP::Method' ),
143 'wrapped_method_metaclass' => (
144 $options->{'wrapped_method_metaclass'}
145 || 'Class::MOP::Method::Wrapped'
147 'instance_metaclass' =>
148 ( $options->{'instance_metaclass'} || 'Class::MOP::Instance' ),
149 'immutable_trait' => (
150 $options->{'immutable_trait'}
151 || 'Class::MOP::Class::Immutable::Trait'
153 'constructor_name' => ( $options->{constructor_name} || 'new' ),
154 'constructor_class' => (
155 $options->{constructor_class} || 'Class::MOP::Method::Constructor'
157 'destructor_class' => $options->{destructor_class},
161 sub reset_package_cache_flag { (shift)->{'_package_cache_flag'} = undef }
162 sub update_package_cache_flag {
165 # we can manually update the cache number
166 # since we are actually adding the method
167 # to our cache as well. This avoids us
168 # having to regenerate the method_map.
170 $self->{'_package_cache_flag'} = Class::MOP::check_package_cache_flag($self->name);
174 sub check_metaclass_compatibility {
175 Carp::cluck('The check_metaclass_compatibility method has been made private.'
176 . " The public version is deprecated and will be removed in a future release.\n");
177 shift->_check_metaclass_compatibility(@_);
180 sub _check_metaclass_compatibility {
183 # this is always okay ...
184 return if ref($self) eq 'Class::MOP::Class' &&
185 $self->instance_metaclass eq 'Class::MOP::Instance';
187 my @class_list = $self->linearized_isa;
188 shift @class_list; # shift off $self->name
190 foreach my $superclass_name (@class_list) {
191 my $super_meta = Class::MOP::get_metaclass_by_name($superclass_name) || next;
194 # we need to deal with the possibility
195 # of class immutability here, and then
196 # get the name of the class appropriately
198 = $super_meta->is_immutable
199 ? $super_meta->get_mutable_metaclass_name()
202 ($self->isa($super_meta_type))
203 || confess "The metaclass of " . $self->name . " ("
204 . (ref($self)) . ")" . " is not compatible with the " .
205 "metaclass of its superclass, ".$superclass_name . " ("
206 . ($super_meta_type) . ")";
208 # we also need to check that instance metaclasses
209 # are compatibile in the same the class.
210 ($self->instance_metaclass->isa($super_meta->instance_metaclass))
211 || confess "The instance metaclass for " . $self->name . " (" . ($self->instance_metaclass) . ")" .
212 " is not compatible with the " .
213 "instance metaclass of its superclass, " . $superclass_name . " (" . ($super_meta->instance_metaclass) . ")";
221 # this should be sufficient, if you have a
222 # use case where it is not, write a test and
224 my $ANON_CLASS_SERIAL = 0;
227 # we need a sufficiently annoying prefix
228 # this should suffice for now, this is
229 # used in a couple of places below, so
230 # need to put it up here for now.
231 my $ANON_CLASS_PREFIX = 'Class::MOP::Class::__ANON__::SERIAL::';
235 no warnings 'uninitialized';
236 $self->name =~ /^$ANON_CLASS_PREFIX/o;
239 sub create_anon_class {
240 my ($class, %options) = @_;
241 my $package_name = $ANON_CLASS_PREFIX . ++$ANON_CLASS_SERIAL;
242 return $class->create($package_name, %options);
246 # this will only get called for
247 # anon-classes, all other calls
248 # are assumed to occur during
249 # global destruction and so don't
250 # really need to be handled explicitly
254 return if in_global_destruction(); # it'll happen soon anyway and this just makes things more complicated
256 no warnings 'uninitialized';
257 my $name = $self->name;
258 return unless $name =~ /^$ANON_CLASS_PREFIX/o;
259 # Moose does a weird thing where it replaces the metaclass for
260 # class when fixing metaclass incompatibility. In that case,
261 # we don't want to clean out the namespace now. We can detect
262 # that because Moose will explicitly update the singleton
263 # cache in Class::MOP.
264 my $current_meta = Class::MOP::get_metaclass_by_name($name);
265 return if $current_meta ne $self;
267 if(my $isa_ref = $self->get_package_symbol('@ISA')){
271 %{ $self->namespace } = ();
273 my ($serial_id) = ($name =~ /^$ANON_CLASS_PREFIX(\d+)/o);
275 Class::MOP::remove_metaclass_by_name($name);
278 delete ${$ANON_CLASS_PREFIX}{$serial_id . '::'};
284 # creating classes with MOP ...
287 my ( $class, @args ) = @_;
289 unshift @args, 'package' if @args % 2 == 1;
291 my (%options) = @args;
292 my $package_name = $options{package};
294 (ref $options{superclasses} eq 'ARRAY')
295 || confess "You must pass an ARRAY ref of superclasses"
296 if exists $options{superclasses};
298 (ref $options{attributes} eq 'ARRAY')
299 || confess "You must pass an ARRAY ref of attributes"
300 if exists $options{attributes};
302 (ref $options{methods} eq 'HASH')
303 || confess "You must pass a HASH ref of methods"
304 if exists $options{methods};
306 my (%initialize_options) = @args;
307 delete @initialize_options{qw(
315 my $meta = $class->initialize( $package_name => %initialize_options );
317 $meta->_instantiate_module( $options{version}, $options{authority} );
320 $meta->add_method('meta' => sub {
321 $class->initialize(ref($_[0]) || $_[0]);
324 $meta->superclasses(@{$options{superclasses}})
325 if exists $options{superclasses};
327 # process attributes first, so that they can
328 # install accessors, but locally defined methods
329 # can then overwrite them. It is maybe a little odd, but
330 # I think this should be the order of things.
331 if (exists $options{attributes}) {
332 foreach my $attr (@{$options{attributes}}) {
333 $meta->add_attribute($attr);
336 if (exists $options{methods}) {
337 foreach my $method_name (keys %{$options{methods}}) {
338 $meta->add_method($method_name, $options{methods}->{$method_name});
347 # all these attribute readers will be bootstrapped
348 # away in the Class::MOP bootstrap section
350 sub get_attribute_map { $_[0]->{'attributes'} }
351 sub attribute_metaclass { $_[0]->{'attribute_metaclass'} }
352 sub instance_metaclass { $_[0]->{'instance_metaclass'} }
353 sub immutable_trait { $_[0]->{'immutable_trait'} }
354 sub constructor_class { $_[0]->{'constructor_class'} }
355 sub constructor_name { $_[0]->{'constructor_name'} }
356 sub destructor_class { $_[0]->{'destructor_class'} }
358 # Instance Construction & Cloning
364 # we need to protect the integrity of the
365 # Class::MOP::Class singletons here, so we
366 # delegate this to &construct_class_instance
367 # which will deal with the singletons
368 return $class->_construct_class_instance(@_)
369 if $class->name->isa('Class::MOP::Class');
370 return $class->_construct_instance(@_);
373 sub construct_instance {
374 Carp::cluck('The construct_instance method has been made private.'
375 . " The public version is deprecated and will be removed in a future release.\n");
376 shift->_construct_instance(@_);
379 sub _construct_instance {
381 my $params = @_ == 1 ? $_[0] : {@_};
382 my $meta_instance = $class->get_meta_instance();
384 # the code below is almost certainly incorrect
385 # but this is foreign inheritance, so we might
386 # have to kludge it in the end.
387 my $instance = $params->{__INSTANCE__} || $meta_instance->create_instance();
388 foreach my $attr ($class->get_all_attributes()) {
389 $attr->initialize_instance_slot($meta_instance, $instance, $params);
392 # this will only work for a HASH instance type
393 if ($class->is_anon_class) {
394 (reftype($instance) eq 'HASH')
395 || confess "Currently only HASH based instances are supported with instance of anon-classes";
397 # At some point we should make this official
398 # as a reserved slot name, but right now I am
399 # going to keep it here.
400 # my $RESERVED_MOP_SLOT = '__MOP__';
401 $instance->{'__MOP__'} = $class;
407 sub get_meta_instance {
409 $self->{'_meta_instance'} ||= $self->_create_meta_instance();
412 sub create_meta_instance {
413 Carp::cluck('The create_meta_instance method has been made private.'
414 . " The public version is deprecated and will be removed in a future release.\n");
415 shift->_create_meta_instance(@_);
418 sub _create_meta_instance {
421 my $instance = $self->instance_metaclass->new(
422 associated_metaclass => $self,
423 attributes => [ $self->get_all_attributes() ],
426 $self->add_meta_instance_dependencies()
427 if $instance->is_dependent_on_superclasses();
434 my $instance = shift;
435 (blessed($instance) && $instance->isa($class->name))
436 || confess "You must pass an instance of the metaclass (" . (ref $class ? $class->name : $class) . "), not ($instance)";
439 # we need to protect the integrity of the
440 # Class::MOP::Class singletons here, they
441 # should not be cloned.
442 return $instance if $instance->isa('Class::MOP::Class');
443 $class->_clone_instance($instance, @_);
447 Carp::cluck('The clone_instance method has been made private.'
448 . " The public version is deprecated and will be removed in a future release.\n");
449 shift->_clone_instance(@_);
452 sub _clone_instance {
453 my ($class, $instance, %params) = @_;
455 || confess "You can only clone instances, ($instance) is not a blessed instance";
456 my $meta_instance = $class->get_meta_instance();
457 my $clone = $meta_instance->clone_instance($instance);
458 foreach my $attr ($class->get_all_attributes()) {
459 if ( defined( my $init_arg = $attr->init_arg ) ) {
460 if (exists $params{$init_arg}) {
461 $attr->set_value($clone, $params{$init_arg});
468 sub rebless_instance {
469 my ($self, $instance, %params) = @_;
471 my $old_metaclass = Class::MOP::class_of($instance);
473 my $old_class = $old_metaclass ? $old_metaclass->name : blessed($instance);
474 $self->name->isa($old_class)
475 || confess "You may rebless only into a subclass of ($old_class), of which (". $self->name .") isn't.";
477 $old_metaclass->rebless_instance_away($instance, $self, %params)
480 my $meta_instance = $self->get_meta_instance();
483 # we use $_[1] here because of t/306_rebless_overload.t regressions on 5.8.8
484 $meta_instance->rebless_instance_structure($_[1], $self);
486 foreach my $attr ( $self->get_all_attributes ) {
487 if ( $attr->has_value($instance) ) {
488 if ( defined( my $init_arg = $attr->init_arg ) ) {
489 $params{$init_arg} = $attr->get_value($instance)
490 unless exists $params{$init_arg};
493 $attr->set_value($instance, $attr->get_value($instance));
498 foreach my $attr ($self->get_all_attributes) {
499 $attr->initialize_instance_slot($meta_instance, $instance, \%params);
505 sub rebless_instance_away {
506 # this intentionally does nothing, it is just a hook
515 @{$self->get_package_symbol('@ISA', create => 1)} = @supers;
518 # on 5.8 and below, we need to call
519 # a method to get Perl to detect
520 # a cycle in the class hierarchy
521 my $class = $self->name;
525 # we need to check the metaclass
526 # compatibility here so that we can
527 # be sure that the superclass is
528 # not potentially creating an issues
529 # we don't know about
531 $self->_check_metaclass_compatibility();
532 $self->_superclasses_updated();
534 @{$self->get_package_symbol('@ISA', create => 1)};
537 sub _superclasses_updated {
539 $self->update_meta_instance_dependencies();
544 my $super_class = $self->name;
546 return @{ $super_class->mro::get_isarev() };
549 sub direct_subclasses {
551 my $super_class = $self->name;
556 } Class::MOP::Class->initialize($_)->superclasses
561 return @{ mro::get_linear_isa( (shift)->name ) };
564 sub class_precedence_list {
566 my $name = $self->name;
568 unless (Class::MOP::IS_RUNNING_ON_5_10()) {
570 # We need to check for circular inheritance here
571 # if we are are not on 5.10, cause 5.8 detects it
572 # late. This will do nothing if all is well, and
573 # blow up otherwise. Yes, it's an ugly hack, better
574 # suggestions are welcome.
576 ($name || return)->isa('This is a test for circular inheritance')
579 # if our mro is c3, we can
580 # just grab the linear_isa
581 if (mro::get_mro($name) eq 'c3') {
582 return @{ mro::get_linear_isa($name) }
586 # we can't grab the linear_isa for dfs
587 # since it has all the duplicates
592 $self->initialize($_)->class_precedence_list()
593 } $self->superclasses()
601 my $fetch_and_prepare_method = sub {
602 my ($self, $method_name) = @_;
603 my $wrapped_metaclass = $self->wrapped_method_metaclass;
605 my $method = $self->get_method($method_name);
606 # if we dont have local ...
608 # try to find the next method
609 $method = $self->find_next_method_by_name($method_name);
610 # die if it does not exist
612 || confess "The method '$method_name' was not found in the inheritance hierarchy for " . $self->name;
613 # and now make sure to wrap it
614 # even if it is already wrapped
615 # because we need a new sub ref
616 $method = $wrapped_metaclass->wrap($method,
617 package_name => $self->name,
618 name => $method_name,
622 # now make sure we wrap it properly
623 $method = $wrapped_metaclass->wrap($method,
624 package_name => $self->name,
625 name => $method_name,
626 ) unless $method->isa($wrapped_metaclass);
628 $self->add_method($method_name => $method);
632 sub add_before_method_modifier {
633 my ($self, $method_name, $method_modifier) = @_;
634 (defined $method_name && $method_name)
635 || confess "You must pass in a method name";
636 my $method = $fetch_and_prepare_method->($self, $method_name);
637 $method->add_before_modifier(
638 subname(':before' => $method_modifier)
642 sub add_after_method_modifier {
643 my ($self, $method_name, $method_modifier) = @_;
644 (defined $method_name && $method_name)
645 || confess "You must pass in a method name";
646 my $method = $fetch_and_prepare_method->($self, $method_name);
647 $method->add_after_modifier(
648 subname(':after' => $method_modifier)
652 sub add_around_method_modifier {
653 my ($self, $method_name, $method_modifier) = @_;
654 (defined $method_name && $method_name)
655 || confess "You must pass in a method name";
656 my $method = $fetch_and_prepare_method->($self, $method_name);
657 $method->add_around_modifier(
658 subname(':around' => $method_modifier)
663 # the methods above used to be named like this:
664 # ${pkg}::${method}:(before|after|around)
665 # but this proved problematic when using one modifier
666 # to wrap multiple methods (something which is likely
667 # to happen pretty regularly IMO). So instead of naming
668 # it like this, I have chosen to just name them purely
669 # with their modifier names, like so:
670 # :(before|after|around)
671 # The fact is that in a stack trace, it will be fairly
672 # evident from the context what method they are attached
673 # to, and so don't need the fully qualified name.
677 Carp::cluck("The alias_method method is deprecated. Use add_method instead.\n");
679 shift->add_method(@_);
682 sub find_method_by_name {
683 my ($self, $method_name) = @_;
684 (defined $method_name && $method_name)
685 || confess "You must define a method name to find";
686 foreach my $class ($self->linearized_isa) {
687 my $method = $self->initialize($class)->get_method($method_name);
688 return $method if defined $method;
693 sub get_all_methods {
695 my %methods = map { %{ $self->initialize($_)->get_method_map } } reverse $self->linearized_isa;
696 return values %methods;
699 sub compute_all_applicable_methods {
700 Carp::cluck('The compute_all_applicable_methods method is deprecated.'
701 . " Use get_all_methods instead.\n");
706 class => $_->package_name,
707 code => $_, # sigh, overloading
709 } shift->get_all_methods(@_);
712 sub get_all_method_names {
715 return grep { !$uniq{$_}++ } map { $self->initialize($_)->get_method_list } $self->linearized_isa;
718 sub find_all_methods_by_name {
719 my ($self, $method_name) = @_;
720 (defined $method_name && $method_name)
721 || confess "You must define a method name to find";
723 foreach my $class ($self->linearized_isa) {
724 # fetch the meta-class ...
725 my $meta = $self->initialize($class);
727 name => $method_name,
729 code => $meta->get_method($method_name)
730 } if $meta->has_method($method_name);
735 sub find_next_method_by_name {
736 my ($self, $method_name) = @_;
737 (defined $method_name && $method_name)
738 || confess "You must define a method name to find";
739 my @cpl = $self->linearized_isa;
740 shift @cpl; # discard ourselves
741 foreach my $class (@cpl) {
742 my $method = $self->initialize($class)->get_method($method_name);
743 return $method if defined $method;
752 # either we have an attribute object already
753 # or we need to create one from the args provided
754 my $attribute = blessed($_[0]) ? $_[0] : $self->attribute_metaclass->new(@_);
755 # make sure it is derived from the correct type though
756 ($attribute->isa('Class::MOP::Attribute'))
757 || confess "Your attribute must be an instance of Class::MOP::Attribute (or a subclass)";
759 # first we attach our new attribute
760 # because it might need certain information
761 # about the class which it is attached to
762 $attribute->attach_to_class($self);
764 my $attr_name = $attribute->name;
766 # then we remove attributes of a conflicting
767 # name here so that we can properly detach
768 # the old attr object, and remove any
769 # accessors it would have generated
770 if ( $self->has_attribute($attr_name) ) {
771 $self->remove_attribute($attr_name);
773 $self->invalidate_meta_instances();
776 # get our count of previously inserted attributes and
777 # increment by one so this attribute knows its order
778 my $order = (scalar keys %{$self->get_attribute_map});
779 $attribute->_set_insertion_order($order);
781 # then onto installing the new accessors
782 $self->get_attribute_map->{$attr_name} = $attribute;
784 # invalidate package flag here
788 eval { $attribute->install_accessors() };
792 $self->remove_attribute($attr_name);
799 sub update_meta_instance_dependencies {
802 if ( $self->{meta_instance_dependencies} ) {
803 return $self->add_meta_instance_dependencies;
807 sub add_meta_instance_dependencies {
810 $self->remove_meta_instance_dependencies;
812 my @attrs = $self->get_all_attributes();
815 my @classes = grep { not $seen{$_->name}++ } map { $_->associated_class } @attrs;
817 foreach my $class ( @classes ) {
818 $class->add_dependent_meta_instance($self);
821 $self->{meta_instance_dependencies} = \@classes;
824 sub remove_meta_instance_dependencies {
827 if ( my $classes = delete $self->{meta_instance_dependencies} ) {
828 foreach my $class ( @$classes ) {
829 $class->remove_dependent_meta_instance($self);
839 sub add_dependent_meta_instance {
840 my ( $self, $metaclass ) = @_;
841 push @{ $self->{dependent_meta_instances} }, $metaclass;
844 sub remove_dependent_meta_instance {
845 my ( $self, $metaclass ) = @_;
846 my $name = $metaclass->name;
847 @$_ = grep { $_->name ne $name } @$_ for $self->{dependent_meta_instances};
850 sub invalidate_meta_instances {
852 $_->invalidate_meta_instance() for $self, @{ $self->{dependent_meta_instances} };
855 sub invalidate_meta_instance {
857 undef $self->{_meta_instance};
861 my ($self, $attribute_name) = @_;
862 (defined $attribute_name)
863 || confess "You must define an attribute name";
864 exists $self->get_attribute_map->{$attribute_name};
868 my ($self, $attribute_name) = @_;
869 (defined $attribute_name)
870 || confess "You must define an attribute name";
871 return $self->get_attribute_map->{$attribute_name}
873 # this will return undef anyway, so no need ...
874 # if $self->has_attribute($attribute_name);
878 sub remove_attribute {
879 my ($self, $attribute_name) = @_;
880 (defined $attribute_name)
881 || confess "You must define an attribute name";
882 my $removed_attribute = $self->get_attribute_map->{$attribute_name};
883 return unless defined $removed_attribute;
884 delete $self->get_attribute_map->{$attribute_name};
885 $self->invalidate_meta_instances();
886 $removed_attribute->remove_accessors();
887 $removed_attribute->detach_from_class();
888 return $removed_attribute;
891 sub get_attribute_list {
893 keys %{$self->get_attribute_map};
896 sub get_all_attributes {
898 my %attrs = map { %{ $self->initialize($_)->get_attribute_map } } reverse $self->linearized_isa;
899 return values %attrs;
902 sub compute_all_applicable_attributes {
903 Carp::cluck('The compute_all_applicable_attributes method has been deprecated.'
904 . " Use get_all_attributes instead.\n");
906 shift->get_all_attributes(@_);
909 sub find_attribute_by_name {
910 my ($self, $attr_name) = @_;
911 foreach my $class ($self->linearized_isa) {
912 # fetch the meta-class ...
913 my $meta = $self->initialize($class);
914 return $meta->get_attribute($attr_name)
915 if $meta->has_attribute($attr_name);
920 # check if we can reinitialize
924 # if any local attr is defined
925 return if $self->get_attribute_list;
927 # or any non-declared methods
928 if ( my @methods = values %{ $self->get_method_map } ) {
929 my $metaclass = $self->method_metaclass;
930 foreach my $method ( @methods ) {
931 return if $method->isa("Class::MOP::Method::Generated");
932 # FIXME do we need to enforce this too? return unless $method->isa($metaclass);
942 sub is_immutable { 0 }
944 sub _immutable_options {
945 my ( $self, @args ) = @_;
948 inline_accessors => 1,
949 inline_constructor => 1,
950 inline_destructor => 0,
952 immutable_trait => $self->immutable_trait,
953 constructor_name => $self->constructor_name,
954 constructor_class => $self->constructor_class,
955 destructor_class => $self->destructor_class,
961 my ( $self, @args ) = @_;
963 if ( $self->is_mutable ) {
964 $self->_initialize_immutable( $self->_immutable_options(@args) );
965 $self->_rebless_as_immutable(@args);
976 if ( $self->is_immutable ) {
977 my @args = $self->immutable_options;
978 $self->_rebless_as_mutable();
979 $self->_remove_inlined_code(@args);
980 delete $self->{__immutable};
988 sub _rebless_as_immutable {
989 my ( $self, @args ) = @_;
991 $self->{__immutable}{original_class} = ref $self;
993 bless $self => $self->_immutable_metaclass(@args);
996 sub _immutable_metaclass {
997 my ( $self, %args ) = @_;
999 if ( my $class = $args{immutable_metaclass} ) {
1003 my $trait = $args{immutable_trait} = $self->immutable_trait
1004 || confess "no immutable trait specified for $self";
1006 my $meta = $self->meta;
1007 my $meta_attr = $meta->find_attribute_by_name("immutable_trait");
1011 if ( $meta_attr and $trait eq $meta_attr->default ) {
1012 # if the trait is the same as the default we try and pick a
1013 # predictable name for the immutable metaclass
1014 $class_name = 'Class::MOP::Class::Immutable::' . ref($self);
1017 $class_name = join '::', 'Class::MOP::Class::Immutable::CustomTrait',
1018 $trait, 'ForMetaClass', ref($self);
1022 if Class::MOP::is_class_loaded($class_name);
1024 # If the metaclass is a subclass of CMOP::Class which has had
1025 # metaclass roles applied (via Moose), then we want to make sure
1026 # that we preserve that anonymous class (see Fey::ORM for an
1027 # example of where this matters).
1029 = $meta->is_immutable
1030 ? $meta->get_mutable_metaclass_name
1033 my $immutable_meta = $meta_name->create(
1035 superclasses => [ ref $self ],
1038 Class::MOP::load_class($trait);
1039 for my $meth ( Class::MOP::Class->initialize($trait)->get_all_methods ) {
1040 my $meth_name = $meth->name;
1042 if ( $immutable_meta->find_method_by_name( $meth_name ) ) {
1043 $immutable_meta->add_around_method_modifier( $meth_name, $meth->body );
1046 $immutable_meta->add_method( $meth_name, $meth->clone );
1050 $immutable_meta->make_immutable(
1051 inline_constructor => 0,
1052 inline_accessors => 0,
1058 sub _remove_inlined_code {
1061 $self->remove_method( $_->name ) for $self->_inlined_methods;
1063 delete $self->{__immutable}{inlined_methods};
1066 sub _inlined_methods { @{ $_[0]{__immutable}{inlined_methods} || [] } }
1068 sub _add_inlined_method {
1069 my ( $self, $method ) = @_;
1071 push @{ $self->{__immutable}{inlined_methods} ||= [] }, $method;
1074 sub _initialize_immutable {
1075 my ( $self, %args ) = @_;
1077 $self->{__immutable}{options} = \%args;
1078 $self->_install_inlined_code(%args);
1081 sub _install_inlined_code {
1082 my ( $self, %args ) = @_;
1085 $self->_inline_accessors(%args) if $args{inline_accessors};
1086 $self->_inline_constructor(%args) if $args{inline_constructor};
1087 $self->_inline_destructor(%args) if $args{inline_destructor};
1090 sub _rebless_as_mutable {
1093 bless $self, $self->get_mutable_metaclass_name;
1098 sub _inline_accessors {
1101 foreach my $attr_name ( $self->get_attribute_list ) {
1102 $self->get_attribute($attr_name)->install_accessors(1);
1106 sub _inline_constructor {
1107 my ( $self, %args ) = @_;
1109 my $name = $args{constructor_name};
1111 if ( $self->has_method($name) && !$args{replace_constructor} ) {
1112 my $class = $self->name;
1113 warn "Not inlining a constructor for $class since it defines"
1114 . " its own constructor.\n"
1115 . "If you are certain you don't need to inline your"
1116 . " constructor, specify inline_constructor => 0 in your"
1117 . " call to $class->meta->make_immutable\n";
1121 my $constructor_class = $args{constructor_class};
1123 Class::MOP::load_class($constructor_class);
1125 my $constructor = $constructor_class->new(
1129 package_name => $self->name,
1133 if ( $args{replace_constructor} or $constructor->can_be_inlined ) {
1134 $self->add_method( $name => $constructor );
1135 $self->_add_inlined_method($constructor);
1139 sub _inline_destructor {
1140 my ( $self, %args ) = @_;
1142 ( exists $args{destructor_class} && defined $args{destructor_class} )
1143 || confess "The 'inline_destructor' option is present, but "
1144 . "no destructor class was specified";
1146 if ( $self->has_method('DESTROY') && ! $args{replace_destructor} ) {
1147 my $class = $self->name;
1148 warn "Not inlining a destructor for $class since it defines"
1149 . " its own destructor.\n";
1153 my $destructor_class = $args{destructor_class};
1155 Class::MOP::load_class($destructor_class);
1157 return unless $destructor_class->is_needed($self);
1159 my $destructor = $destructor_class->new(
1162 package_name => $self->name,
1166 if ( $args{replace_destructor} or $destructor->can_be_inlined ) {
1167 $self->add_method( 'DESTROY' => $destructor );
1168 $self->_add_inlined_method($destructor);
1180 Class::MOP::Class - Class Meta Object
1184 # assuming that class Foo
1185 # has been defined, you can
1187 # use this for introspection ...
1189 # add a method to Foo ...
1190 Foo->meta->add_method( 'bar' => sub {...} )
1192 # get a list of all the classes searched
1193 # the method dispatcher in the correct order
1194 Foo->meta->class_precedence_list()
1196 # remove a method from Foo
1197 Foo->meta->remove_method('bar');
1199 # or use this to actually create classes ...
1201 Class::MOP::Class->create(
1204 superclasses => ['Foo'],
1206 Class::MOP::Attribute->new('$bar'),
1207 Class::MOP::Attribute->new('$baz'),
1210 calculate_bar => sub {...},
1211 construct_baz => sub {...}
1218 The Class Protocol is the largest and most complex part of the
1219 Class::MOP meta-object protocol. It controls the introspection and
1220 manipulation of Perl 5 classes, and it can create them as well. The
1221 best way to understand what this module can do, is to read the
1222 documentation for each of its methods.
1226 C<Class::MOP::Class> is a subclass of L<Class::MOP::Module>.
1230 =head2 Class construction
1232 These methods all create new C<Class::MOP::Class> objects. These
1233 objects can represent existing classes, or they can be used to create
1234 new classes from scratch.
1236 The metaclass object for a given class is a singleton. If you attempt
1237 to create a metaclass for the same class twice, you will just get the
1242 =item B<< Class::MOP::Class->create($package_name, %options) >>
1244 This method creates a new C<Class::MOP::Class> object with the given
1245 package name. It accepts a number of options.
1251 An optional version number for the newly created package.
1255 An optional authority for the newly created package.
1257 =item * superclasses
1259 An optional array reference of superclass names.
1263 An optional hash reference of methods for the class. The keys of the
1264 hash reference are method names, and values are subroutine references.
1268 An optional array reference of L<Class::MOP::Attribute> objects.
1272 =item B<< Class::MOP::Class->create_anon_class(%options) >>
1274 This method works just like C<< Class::MOP::Class->create >> but it
1275 creates an "anonymous" class. In fact, the class does have a name, but
1276 that name is a unique name generated internally by this module.
1278 It accepts the same C<superclasses>, C<methods>, and C<attributes>
1279 parameters that C<create> accepts.
1281 Anonymous classes are destroyed once the metaclass they are attached
1282 to goes out of scope, and will be removed from Perl's internal symbol
1285 All instances of an anonymous class keep a special reference to the
1286 metaclass object, which prevents the metaclass from going out of scope
1287 while any instances exist.
1289 This only works if the instance if based on a hash reference, however.
1291 =item B<< Class::MOP::Class->initialize($package_name, %options) >>
1293 This method will initialize a C<Class::MOP::Class> object for the
1294 named package. Unlike C<create>, this method I<will not> create a new
1297 The purpose of this method is to retrieve a C<Class::MOP::Class>
1298 object for introspecting an existing class.
1300 If an existing C<Class::MOP::Class> object exists for the named
1301 package, it will be returned, and any options provided will be
1304 If the object does not yet exist, it will be created.
1306 The valid options that can be passed to this method are
1307 C<attribute_metaclass>, C<method_metaclass>,
1308 C<wrapped_method_metaclass>, and C<instance_metaclass>. These are all
1309 optional, and default to the appropriate class in the C<Class::MOP>
1314 =head2 Object instance construction and cloning
1316 These methods are all related to creating and/or cloning object
1321 =item B<< $metaclass->clone_object($instance, %params) >>
1323 This method clones an existing object instance. Any parameters you
1324 provide are will override existing attribute values in the object.
1326 This is a convenience method for cloning an object instance, then
1327 blessing it into the appropriate package.
1329 You could implement a clone method in your class, using this method:
1332 my ($self, %params) = @_;
1333 $self->meta->clone_object($self, %params);
1336 =item B<< $metaclass->rebless_instance($instance, %params) >>
1338 This method changes the class of C<$instance> to the metaclass's class.
1340 You can only rebless an instance into a subclass of its current
1341 class. If you pass any additional parameters, these will be treated
1342 like constructor parameters and used to initialize the object's
1343 attributes. Any existing attributes that are already set will be
1346 Before reblessing the instance, this method will call
1347 C<rebless_instance_away> on the instance's current metaclass. This method
1348 will be passed the instance, the new metaclass, and any parameters
1349 specified to C<rebless_instance>. By default, C<rebless_instance_away>
1350 does nothing; it is merely a hook.
1352 =item B<< $metaclass->new_object(%params) >>
1354 This method is used to create a new object of the metaclass's
1355 class. Any parameters you provide are used to initialize the
1356 instance's attributes. A special C<__INSTANCE__> key can be passed to
1357 provide an already generated instance, rather than having Class::MOP
1358 generate it for you. This is mostly useful for using Class::MOP with
1359 foreign classes, which generally generate instances using their own
1362 =item B<< $metaclass->instance_metaclass >>
1364 Returns the class name of the instance metaclass, see
1365 L<Class::MOP::Instance> for more information on the instance
1368 =item B<< $metaclass->get_meta_instance >>
1370 Returns an instance of the C<instance_metaclass> to be used in the
1371 construction of a new instance of the class.
1375 =head2 Informational predicates
1377 These are a few predicate methods for asking information about the
1382 =item B<< $metaclass->is_anon_class >>
1384 This returns true if the class was created by calling C<<
1385 Class::MOP::Class->create_anon_class >>.
1387 =item B<< $metaclass->is_mutable >>
1389 This returns true if the class is still mutable.
1391 =item B<< $metaclass->is_immutable >>
1393 This returns true if the class has been made immutable.
1395 =item B<< $metaclass->is_pristine >>
1397 A class is I<not> pristine if it has non-inherited attributes or if it
1398 has any generated methods.
1402 =head2 Inheritance Relationships
1406 =item B<< $metaclass->superclasses(@superclasses) >>
1408 This is a read-write accessor which represents the superclass
1409 relationships of the metaclass's class.
1411 This is basically sugar around getting and setting C<@ISA>.
1413 =item B<< $metaclass->class_precedence_list >>
1415 This returns a list of all of the class's ancestor classes. The
1416 classes are returned in method dispatch order.
1418 =item B<< $metaclass->linearized_isa >>
1420 This returns a list based on C<class_precedence_list> but with all
1423 =item B<< $metaclass->subclasses >>
1425 This returns a list of all subclasses for this class, even indirect
1428 =item B<< $metaclass->direct_subclasses >>
1430 This returns a list of immediate subclasses for this class, which does not
1431 include indirect subclasses.
1435 =head2 Method introspection
1437 See L<Class::MOP::Package/Method introspection and creation> for
1438 methods that operate only on the current class. Class::MOP::Class adds
1439 introspection capabilities that take inheritance into account.
1443 =item B<< $metaclass->get_all_methods >>
1445 This will traverse the inheritance hierarchy and return a list of all
1446 the L<Class::MOP::Method> objects for this class and its parents.
1448 =item B<< $metaclass->find_method_by_name($method_name) >>
1450 This will return a L<Class::MOP::Method> for the specified
1451 C<$method_name>. If the class does not have the specified method, it
1454 Unlike C<get_method>, this method I<will> look for the named method in
1457 =item B<< $metaclass->get_all_method_names >>
1459 This will return a list of method I<names> for all of this class's
1460 methods, including inherited methods.
1462 =item B<< $metaclass->find_all_methods_by_name($method_name) >>
1464 This method looks for the named method in the class and all of its
1465 parents. It returns every matching method it finds in the inheritance
1466 tree, so it returns a list of methods.
1468 Each method is returned as a hash reference with three keys. The keys
1469 are C<name>, C<class>, and C<code>. The C<code> key has a
1470 L<Class::MOP::Method> object as its value.
1472 The list of methods is distinct.
1474 =item B<< $metaclass->find_next_method_by_name($method_name) >>
1476 This method returns the first method in any superclass matching the
1477 given name. It is effectively the method that C<SUPER::$method_name>
1482 =head2 Attribute introspection and creation
1484 Because Perl 5 does not have a core concept of attributes in classes,
1485 we can only return information about attributes which have been added
1486 via this class's methods. We cannot discover information about
1487 attributes which are defined in terms of "regular" Perl 5 methods.
1491 =item B<< $metaclass->get_attribute($attribute_name) >>
1493 This will return a L<Class::MOP::Attribute> for the specified
1494 C<$attribute_name>. If the class does not have the specified
1495 attribute, it returns C<undef>.
1497 NOTE that get_attribute does not search superclasses, for that you
1498 need to use C<find_attribute_by_name>.
1500 =item B<< $metaclass->has_attribute($attribute_name) >>
1502 Returns a boolean indicating whether or not the class defines the
1503 named attribute. It does not include attributes inherited from parent
1506 =item B<< $metaclass->get_attribute_map >>
1508 Returns a hash reference representing the attributes defined in this
1509 class. The keys are attribute names and the values are
1510 L<Class::MOP::Attribute> objects.
1512 =item B<< $metaclass->get_attribute_list >>
1514 This will return a list of attributes I<names> for all attributes
1515 defined in this class.
1517 =item B<< $metaclass->get_all_attributes >>
1519 This will traverse the inheritance hierarchy and return a list of all
1520 the L<Class::MOP::Attribute> objects for this class and its parents.
1522 =item B<< $metaclass->find_attribute_by_name($attribute_name) >>
1524 This will return a L<Class::MOP::Attribute> for the specified
1525 C<$attribute_name>. If the class does not have the specified
1526 attribute, it returns C<undef>
1528 Unlike C<get_attribute>, this attribute I<will> look for the named
1529 attribute in superclasses.
1531 =item B<< $metaclass->add_attribute(...) >>
1533 This method accepts either an existing L<Class::MOP::Attribute>
1534 object, or parameters suitable for passing to that class's C<new>
1537 The attribute provided will be added to the class.
1539 Any accessor methods defined by the attribute will be added to the
1540 class when the attribute is added.
1542 If an attribute of the same name already exists, the old attribute
1543 will be removed first.
1545 =item B<< $metaclass->remove_attribute($attribute_name) >>
1547 This will remove the named attribute from the class, and
1548 L<Class::MOP::Attribute> object.
1550 Removing an attribute also removes any accessor methods defined by the
1553 However, note that removing an attribute will only affect I<future>
1554 object instances created for this class, not existing instances.
1556 =item B<< $metaclass->attribute_metaclass >>
1558 Returns the class name of the attribute metaclass for this class. By
1559 default, this is L<Class::MOP::Attribute>. for more information on
1563 =head2 Class Immutability
1565 Making a class immutable "freezes" the class definition. You can no
1566 longer call methods which alter the class, such as adding or removing
1567 methods or attributes.
1569 Making a class immutable lets us optimize the class by inlining some
1570 methods, and also allows us to optimize some methods on the metaclass
1573 After immutabilization, the metaclass object will cache most
1574 informational methods such as C<get_method_map> and
1575 C<get_all_attributes>. Methods which would alter the class, such as
1576 C<add_attribute>, C<add_method>, and so on will throw an error on an
1577 immutable metaclass object.
1579 The immutabilization system in L<Moose> takes much greater advantage
1580 of the inlining features than Class::MOP itself does.
1584 =item B<< $metaclass->make_immutable(%options) >>
1586 This method will create an immutable transformer and uses it to make
1587 the class and its metaclass object immutable.
1589 This method accepts the following options:
1593 =item * inline_accessors
1595 =item * inline_constructor
1597 =item * inline_destructor
1599 These are all booleans indicating whether the specified method(s)
1602 By default, accessors and the constructor are inlined, but not the
1605 =item * immutable_trait
1607 The name of a class which will be used as a parent class for the
1608 metaclass object being made immutable. This "trait" implements the
1609 post-immutability functionality of the metaclass (but not the
1610 transformation itself).
1612 This defaults to L<Class::MOP::Class::Immutable::Trait>.
1614 =item * constructor_name
1616 This is the constructor method name. This defaults to "new".
1618 =item * constructor_class
1620 The name of the method metaclass for constructors. It will be used to
1621 generate the inlined constructor. This defaults to
1622 "Class::MOP::Method::Constructor".
1624 =item * replace_constructor
1626 This is a boolean indicating whether an existing constructor should be
1627 replaced when inlining a constructor. This defaults to false.
1629 =item * destructor_class
1631 The name of the method metaclass for destructors. It will be used to
1632 generate the inlined destructor. This defaults to
1633 "Class::MOP::Method::Denstructor".
1635 =item * replace_destructor
1637 This is a boolean indicating whether an existing destructor should be
1638 replaced when inlining a destructor. This defaults to false.
1642 =item B<< $metaclass->make_mutable >>
1644 Calling this method reverse the immutabilization transformation.
1648 =head2 Method Modifiers
1650 Method modifiers are hooks which allow a method to be wrapped with
1651 I<before>, I<after> and I<around> method modifiers. Every time a
1652 method is called, it's modifiers are also called.
1654 A class can modify its own methods, as well as methods defined in
1657 =head3 How method modifiers work?
1659 Method modifiers work by wrapping the original method and then
1660 replacing it in the class's symbol table. The wrappers will handle
1661 calling all the modifiers in the appropriate order and preserving the
1662 calling context for the original method.
1664 The return values of C<before> and C<after> modifiers are
1665 ignored. This is because their purpose is B<not> to filter the input
1666 and output of the primary method (this is done with an I<around>
1669 This may seem like an odd restriction to some, but doing this allows
1670 for simple code to be added at the beginning or end of a method call
1671 without altering the function of the wrapped method or placing any
1672 extra responsibility on the code of the modifier.
1674 Of course if you have more complex needs, you can use the C<around>
1675 modifier which allows you to change both the parameters passed to the
1676 wrapped method, as well as its return value.
1678 Before and around modifiers are called in last-defined-first-called
1679 order, while after modifiers are called in first-defined-first-called
1680 order. So the call tree might looks something like this:
1692 =head3 What is the performance impact?
1694 Of course there is a performance cost associated with method
1695 modifiers, but we have made every effort to make that cost directly
1696 proportional to the number of modifier features you utilize.
1698 The wrapping method does it's best to B<only> do as much work as it
1699 absolutely needs to. In order to do this we have moved some of the
1700 performance costs to set-up time, where they are easier to amortize.
1702 All this said, our benchmarks have indicated the following:
1704 simple wrapper with no modifiers 100% slower
1705 simple wrapper with simple before modifier 400% slower
1706 simple wrapper with simple after modifier 450% slower
1707 simple wrapper with simple around modifier 500-550% slower
1708 simple wrapper with all 3 modifiers 1100% slower
1710 These numbers may seem daunting, but you must remember, every feature
1711 comes with some cost. To put things in perspective, just doing a
1712 simple C<AUTOLOAD> which does nothing but extract the name of the
1713 method called and return it costs about 400% over a normal method
1718 =item B<< $metaclass->add_before_method_modifier($method_name, $code) >>
1720 This wraps the specified method with the supplied subroutine
1721 reference. The modifier will be called as a method itself, and will
1722 receive the same arguments as are passed to the method.
1724 When the modifier exits, the wrapped method will be called.
1726 The return value of the modifier will be ignored.
1728 =item B<< $metaclass->add_after_method_modifier($method_name, $code) >>
1730 This wraps the specified method with the supplied subroutine
1731 reference. The modifier will be called as a method itself, and will
1732 receive the same arguments as are passed to the method.
1734 When the wrapped methods exits, the modifier will be called.
1736 The return value of the modifier will be ignored.
1738 =item B<< $metaclass->add_around_method_modifier($method_name, $code) >>
1740 This wraps the specified method with the supplied subroutine
1743 The first argument passed to the modifier will be a subroutine
1744 reference to the wrapped method. The second argument is the object,
1745 and after that come any arguments passed when the method is called.
1747 The around modifier can choose to call the original method, as well as
1748 what arguments to pass if it does so.
1750 The return value of the modifier is what will be seen by the caller.
1754 =head2 Introspection
1758 =item B<< Class::MOP::Class->meta >>
1760 This will return a L<Class::MOP::Class> instance for this class.
1762 It should also be noted that L<Class::MOP> will actually bootstrap
1763 this module by installing a number of attribute meta-objects into its
1770 Stevan Little E<lt>stevan@iinteractive.comE<gt>
1772 =head1 COPYRIGHT AND LICENSE
1774 Copyright 2006-2009 by Infinity Interactive, Inc.
1776 L<http://www.iinteractive.com>
1778 This library is free software; you can redistribute it and/or modify
1779 it under the same terms as Perl itself.