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;
11 use Class::MOP::Class::Immutable::Class::MOP::Class;
14 use Scalar::Util 'blessed', 'weaken';
15 use Sub::Name 'subname';
16 use Devel::GlobalDestruction 'in_global_destruction';
18 our $VERSION = '0.86';
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 (defined $package_name && $package_name && !ref($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 sub construct_class_instance {
46 Carp::cluck('The construct_class_instance method has been made private.'
47 . " The public version is deprecated and will be removed in a future release.\n");
48 shift->_construct_class_instance(@_);
51 # NOTE: (meta-circularity)
52 # this is a special form of _construct_instance
53 # (see below), which is used to construct class
54 # meta-object instances for any Class::MOP::*
55 # class. All other classes will use the more
56 # normal &construct_instance.
57 sub _construct_class_instance {
59 my $options = @_ == 1 ? $_[0] : {@_};
60 my $package_name = $options->{package};
61 (defined $package_name && $package_name)
62 || confess "You must pass a package name";
64 # return the metaclass if we have it cached,
65 # and it is still defined (it has not been
66 # reaped by DESTROY yet, which can happen
67 # annoyingly enough during global destruction)
69 if (defined(my $meta = Class::MOP::get_metaclass_by_name($package_name))) {
74 # we need to deal with the possibility
75 # of class immutability here, and then
76 # get the name of the class appropriately
78 ? ($class->is_immutable
79 ? $class->get_mutable_metaclass_name()
83 # now create the metaclass
85 if ($class eq 'Class::MOP::Class') {
86 $meta = $class->_new($options);
90 # it is safe to use meta here because
91 # class will always be a subclass of
92 # Class::MOP::Class, which defines meta
93 $meta = $class->meta->_construct_instance($options)
96 # and check the metaclass compatibility
97 $meta->_check_metaclass_compatibility();
99 Class::MOP::store_metaclass_by_name($package_name, $meta);
102 # we need to weaken any anon classes
103 # so that they can call DESTROY properly
104 Class::MOP::weaken_metaclass($package_name) if $meta->is_anon_class;
111 my $options = @_ == 1 ? $_[0] : {@_};
114 # inherited from Class::MOP::Package
115 'package' => $options->{package},
118 # since the following attributes will
119 # actually be loaded from the symbol
120 # table, and actually bypass the instance
121 # entirely, we can just leave these things
122 # listed here for reference, because they
123 # should not actually have a value associated
125 'namespace' => \undef,
127 # inherited from Class::MOP::Module
129 'authority' => \undef,
131 # defined in Class::MOP::Class
132 'superclasses' => \undef,
136 'attribute_metaclass' =>
137 ( $options->{'attribute_metaclass'} || 'Class::MOP::Attribute' ),
138 'method_metaclass' =>
139 ( $options->{'method_metaclass'} || 'Class::MOP::Method' ),
140 'wrapped_method_metaclass' => (
141 $options->{'wrapped_method_metaclass'}
142 || 'Class::MOP::Method::Wrapped'
144 'instance_metaclass' =>
145 ( $options->{'instance_metaclass'} || 'Class::MOP::Instance' ),
146 'immutable_trait' => (
147 $options->{'immutable_trait'}
148 || 'Class::MOP::Class::Immutable::Trait'
150 'constructor_name' => ( $options->{constructor_name} || 'new' ),
151 'constructor_class' => (
152 $options->{constructor_class} || 'Class::MOP::Method::Constructor'
154 'destructor_class' => $options->{destructor_class},
158 sub reset_package_cache_flag { (shift)->{'_package_cache_flag'} = undef }
159 sub update_package_cache_flag {
162 # we can manually update the cache number
163 # since we are actually adding the method
164 # to our cache as well. This avoids us
165 # having to regenerate the method_map.
167 $self->{'_package_cache_flag'} = Class::MOP::check_package_cache_flag($self->name);
171 sub check_metaclass_compatibility {
172 Carp::cluck('The check_metaclass_compatibility method has been made private.'
173 . " The public version is deprecated and will be removed in a future release.\n");
174 shift->_check_metaclass_compatibility(@_);
177 sub _check_metaclass_compatibility {
180 # this is always okay ...
181 return if ref($self) eq 'Class::MOP::Class' &&
182 $self->instance_metaclass eq 'Class::MOP::Instance';
184 my @class_list = $self->linearized_isa;
185 shift @class_list; # shift off $self->name
187 foreach my $superclass_name (@class_list) {
188 my $super_meta = Class::MOP::get_metaclass_by_name($superclass_name) || next;
191 # we need to deal with the possibility
192 # of class immutability here, and then
193 # get the name of the class appropriately
195 = $super_meta->is_immutable
196 ? $super_meta->get_mutable_metaclass_name()
199 ($self->isa($super_meta_type))
200 || confess "Class::MOP::class_of(" . $self->name . ") => ("
201 . (ref($self)) . ")" . " is not compatible with the " .
202 "Class::MOP::class_of(".$superclass_name . ") => ("
203 . ($super_meta_type) . ")";
205 # we also need to check that instance metaclasses
206 # are compatibile in the same the class.
207 ($self->instance_metaclass->isa($super_meta->instance_metaclass))
208 || confess "Class::MOP::class_of(" . $self->name . ")->instance_metaclass => (" . ($self->instance_metaclass) . ")" .
209 " is not compatible with the " .
210 "Class::MOP::class_of(" . $superclass_name . ")->instance_metaclass => (" . ($super_meta->instance_metaclass) . ")";
218 # this should be sufficient, if you have a
219 # use case where it is not, write a test and
221 my $ANON_CLASS_SERIAL = 0;
224 # we need a sufficiently annoying prefix
225 # this should suffice for now, this is
226 # used in a couple of places below, so
227 # need to put it up here for now.
228 my $ANON_CLASS_PREFIX = 'Class::MOP::Class::__ANON__::SERIAL::';
232 no warnings 'uninitialized';
233 $self->name =~ /^$ANON_CLASS_PREFIX/;
236 sub create_anon_class {
237 my ($class, %options) = @_;
238 my $package_name = $ANON_CLASS_PREFIX . ++$ANON_CLASS_SERIAL;
239 return $class->create($package_name, %options);
243 # this will only get called for
244 # anon-classes, all other calls
245 # are assumed to occur during
246 # global destruction and so don't
247 # really need to be handled explicitly
251 return if in_global_destruction(); # it'll happen soon anyway and this just makes things more complicated
253 no warnings 'uninitialized';
254 return unless $self->name =~ /^$ANON_CLASS_PREFIX/;
255 # Moose does a weird thing where it replaces the metaclass for
256 # class when fixing metaclass incompatibility. In that case,
257 # we don't want to clean out the namespace now. We can detect
258 # that because Moose will explicitly update the singleton
259 # cache in Class::MOP.
260 my $current_meta = Class::MOP::get_metaclass_by_name($self->name);
261 return if $current_meta ne $self;
263 my ($serial_id) = ($self->name =~ /^$ANON_CLASS_PREFIX(\d+)/);
265 foreach my $key (keys %{$ANON_CLASS_PREFIX . $serial_id}) {
266 delete ${$ANON_CLASS_PREFIX . $serial_id}{$key};
268 delete ${'main::' . $ANON_CLASS_PREFIX}{$serial_id . '::'};
273 # creating classes with MOP ...
276 my ( $class, @args ) = @_;
278 unshift @args, 'package' if @args % 2 == 1;
280 my (%options) = @args;
281 my $package_name = $options{package};
283 (ref $options{superclasses} eq 'ARRAY')
284 || confess "You must pass an ARRAY ref of superclasses"
285 if exists $options{superclasses};
287 (ref $options{attributes} eq 'ARRAY')
288 || confess "You must pass an ARRAY ref of attributes"
289 if exists $options{attributes};
291 (ref $options{methods} eq 'HASH')
292 || confess "You must pass a HASH ref of methods"
293 if exists $options{methods};
295 my (%initialize_options) = @args;
296 delete @initialize_options{qw(
304 my $meta = $class->initialize( $package_name => %initialize_options );
306 $meta->_instantiate_module( $options{version}, $options{authority} );
309 $meta->add_method('meta' => sub {
310 $class->initialize(ref($_[0]) || $_[0]);
313 $meta->superclasses(@{$options{superclasses}})
314 if exists $options{superclasses};
316 # process attributes first, so that they can
317 # install accessors, but locally defined methods
318 # can then overwrite them. It is maybe a little odd, but
319 # I think this should be the order of things.
320 if (exists $options{attributes}) {
321 foreach my $attr (@{$options{attributes}}) {
322 $meta->add_attribute($attr);
325 if (exists $options{methods}) {
326 foreach my $method_name (keys %{$options{methods}}) {
327 $meta->add_method($method_name, $options{methods}->{$method_name});
336 # all these attribute readers will be bootstrapped
337 # away in the Class::MOP bootstrap section
339 sub get_attribute_map { $_[0]->{'attributes'} }
340 sub attribute_metaclass { $_[0]->{'attribute_metaclass'} }
341 sub method_metaclass { $_[0]->{'method_metaclass'} }
342 sub wrapped_method_metaclass { $_[0]->{'wrapped_method_metaclass'} }
343 sub instance_metaclass { $_[0]->{'instance_metaclass'} }
344 sub immutable_trait { $_[0]->{'immutable_trait'} }
345 sub constructor_class { $_[0]->{'constructor_class'} }
346 sub constructor_name { $_[0]->{'constructor_name'} }
347 sub destructor_class { $_[0]->{'destructor_class'} }
349 # Instance Construction & Cloning
355 # we need to protect the integrity of the
356 # Class::MOP::Class singletons here, so we
357 # delegate this to &construct_class_instance
358 # which will deal with the singletons
359 return $class->_construct_class_instance(@_)
360 if $class->name->isa('Class::MOP::Class');
361 return $class->_construct_instance(@_);
364 sub construct_instance {
365 Carp::cluck('The construct_instance method has been made private.'
366 . " The public version is deprecated and will be removed in a future release.\n");
367 shift->_construct_instance(@_);
370 sub _construct_instance {
372 my $params = @_ == 1 ? $_[0] : {@_};
373 my $meta_instance = $class->get_meta_instance();
374 my $instance = $meta_instance->create_instance();
375 foreach my $attr ($class->get_all_attributes()) {
376 $attr->initialize_instance_slot($meta_instance, $instance, $params);
379 # this will only work for a HASH instance type
380 if ($class->is_anon_class) {
381 (Scalar::Util::reftype($instance) eq 'HASH')
382 || confess "Currently only HASH based instances are supported with instance of anon-classes";
384 # At some point we should make this official
385 # as a reserved slot name, but right now I am
386 # going to keep it here.
387 # my $RESERVED_MOP_SLOT = '__MOP__';
388 $instance->{'__MOP__'} = $class;
394 sub get_meta_instance {
396 $self->{'_meta_instance'} ||= $self->_create_meta_instance();
399 sub create_meta_instance {
400 Carp::cluck('The create_meta_instance method has been made private.'
401 . " The public version is deprecated and will be removed in a future release.\n");
402 shift->_create_meta_instance(@_);
405 sub _create_meta_instance {
408 my $instance = $self->instance_metaclass->new(
409 associated_metaclass => $self,
410 attributes => [ $self->get_all_attributes() ],
413 $self->add_meta_instance_dependencies()
414 if $instance->is_dependent_on_superclasses();
421 my $instance = shift;
422 (blessed($instance) && $instance->isa($class->name))
423 || confess "You must pass an instance of the metaclass (" . (ref $class ? $class->name : $class) . "), not ($instance)";
426 # we need to protect the integrity of the
427 # Class::MOP::Class singletons here, they
428 # should not be cloned.
429 return $instance if $instance->isa('Class::MOP::Class');
430 $class->_clone_instance($instance, @_);
434 Carp::cluck('The clone_instance method has been made private.'
435 . " The public version is deprecated and will be removed in a future release.\n");
436 shift->_clone_instance(@_);
439 sub _clone_instance {
440 my ($class, $instance, %params) = @_;
442 || confess "You can only clone instances, ($instance) is not a blessed instance";
443 my $meta_instance = $class->get_meta_instance();
444 my $clone = $meta_instance->clone_instance($instance);
445 foreach my $attr ($class->get_all_attributes()) {
446 if ( defined( my $init_arg = $attr->init_arg ) ) {
447 if (exists $params{$init_arg}) {
448 $attr->set_value($clone, $params{$init_arg});
455 sub rebless_instance {
456 my ($self, $instance, %params) = @_;
458 my $old_metaclass = Class::MOP::class_of($instance);
460 my $old_class = $old_metaclass ? $old_metaclass->name : blessed($instance);
461 $self->name->isa($old_class)
462 || confess "You may rebless only into a subclass of ($old_class), of which (". $self->name .") isn't.";
464 $old_metaclass->rebless_instance_away($instance, $self, %params)
467 my $meta_instance = $self->get_meta_instance();
470 # we use $_[1] here because of t/306_rebless_overload.t regressions on 5.8.8
471 $meta_instance->rebless_instance_structure($_[1], $self);
473 foreach my $attr ( $self->get_all_attributes ) {
474 if ( $attr->has_value($instance) ) {
475 if ( defined( my $init_arg = $attr->init_arg ) ) {
476 $params{$init_arg} = $attr->get_value($instance)
477 unless exists $params{$init_arg};
480 $attr->set_value($instance, $attr->get_value($instance));
485 foreach my $attr ($self->get_all_attributes) {
486 $attr->initialize_instance_slot($meta_instance, $instance, \%params);
492 sub rebless_instance_away {
493 # this intentionally does nothing, it is just a hook
500 my $var_spec = { sigil => '@', type => 'ARRAY', name => 'ISA' };
503 @{$self->get_package_symbol($var_spec)} = @supers;
506 # on 5.8 and below, we need to call
507 # a method to get Perl to detect
508 # a cycle in the class hierarchy
509 my $class = $self->name;
513 # we need to check the metaclass
514 # compatibility here so that we can
515 # be sure that the superclass is
516 # not potentially creating an issues
517 # we don't know about
519 $self->_check_metaclass_compatibility();
520 $self->_superclasses_updated();
522 @{$self->get_package_symbol($var_spec)};
525 sub _superclasses_updated {
527 $self->update_meta_instance_dependencies();
532 my $super_class = $self->name;
534 return @{ $super_class->mro::get_isarev() };
537 sub direct_subclasses {
539 my $super_class = $self->name;
544 } Class::MOP::Class->initialize($_)->superclasses
549 return @{ mro::get_linear_isa( (shift)->name ) };
552 sub class_precedence_list {
554 my $name = $self->name;
556 unless (Class::MOP::IS_RUNNING_ON_5_10()) {
558 # We need to check for circular inheritance here
559 # if we are are not on 5.10, cause 5.8 detects it
560 # late. This will do nothing if all is well, and
561 # blow up otherwise. Yes, it's an ugly hack, better
562 # suggestions are welcome.
564 ($name || return)->isa('This is a test for circular inheritance')
567 # if our mro is c3, we can
568 # just grab the linear_isa
569 if (mro::get_mro($name) eq 'c3') {
570 return @{ mro::get_linear_isa($name) }
574 # we can't grab the linear_isa for dfs
575 # since it has all the duplicates
580 $self->initialize($_)->class_precedence_list()
581 } $self->superclasses()
588 sub wrap_method_body {
589 my ( $self, %args ) = @_;
591 ('CODE' eq ref $args{body})
592 || confess "Your code block must be a CODE reference";
594 $self->method_metaclass->wrap(
595 package_name => $self->name,
601 my ($self, $method_name, $method) = @_;
602 (defined $method_name && $method_name)
603 || confess "You must define a method name";
606 if (blessed($method)) {
607 $body = $method->body;
608 if ($method->package_name ne $self->name) {
609 $method = $method->clone(
610 package_name => $self->name,
612 ) if $method->can('clone');
617 $method = $self->wrap_method_body( body => $body, name => $method_name );
620 $method->attach_to_class($self);
622 $self->get_method_map->{$method_name} = $method;
624 my ( $current_package, $current_name ) = Class::MOP::get_code_info($body);
626 if ( $current_name eq '__ANON__' ) {
627 my $full_method_name = ($self->name . '::' . $method_name);
628 subname($full_method_name => $body);
631 $self->add_package_symbol(
632 { sigil => '&', type => 'CODE', name => $method_name },
638 my $fetch_and_prepare_method = sub {
639 my ($self, $method_name) = @_;
640 my $wrapped_metaclass = $self->wrapped_method_metaclass;
642 my $method = $self->get_method($method_name);
643 # if we dont have local ...
645 # try to find the next method
646 $method = $self->find_next_method_by_name($method_name);
647 # die if it does not exist
649 || confess "The method '$method_name' was not found in the inheritance hierarchy for " . $self->name;
650 # and now make sure to wrap it
651 # even if it is already wrapped
652 # because we need a new sub ref
653 $method = $wrapped_metaclass->wrap($method);
656 # now make sure we wrap it properly
657 $method = $wrapped_metaclass->wrap($method)
658 unless $method->isa($wrapped_metaclass);
660 $self->add_method($method_name => $method);
664 sub add_before_method_modifier {
665 my ($self, $method_name, $method_modifier) = @_;
666 (defined $method_name && $method_name)
667 || confess "You must pass in a method name";
668 my $method = $fetch_and_prepare_method->($self, $method_name);
669 $method->add_before_modifier(
670 subname(':before' => $method_modifier)
674 sub add_after_method_modifier {
675 my ($self, $method_name, $method_modifier) = @_;
676 (defined $method_name && $method_name)
677 || confess "You must pass in a method name";
678 my $method = $fetch_and_prepare_method->($self, $method_name);
679 $method->add_after_modifier(
680 subname(':after' => $method_modifier)
684 sub add_around_method_modifier {
685 my ($self, $method_name, $method_modifier) = @_;
686 (defined $method_name && $method_name)
687 || confess "You must pass in a method name";
688 my $method = $fetch_and_prepare_method->($self, $method_name);
689 $method->add_around_modifier(
690 subname(':around' => $method_modifier)
695 # the methods above used to be named like this:
696 # ${pkg}::${method}:(before|after|around)
697 # but this proved problematic when using one modifier
698 # to wrap multiple methods (something which is likely
699 # to happen pretty regularly IMO). So instead of naming
700 # it like this, I have chosen to just name them purely
701 # with their modifier names, like so:
702 # :(before|after|around)
703 # The fact is that in a stack trace, it will be fairly
704 # evident from the context what method they are attached
705 # to, and so don't need the fully qualified name.
709 Carp::cluck("The alias_method method is deprecated. Use add_method instead.\n");
711 shift->add_method(@_);
715 my ($self, $method_name) = @_;
716 (defined $method_name && $method_name)
717 || confess "You must define a method name";
719 exists $self->get_method_map->{$method_name};
723 my ($self, $method_name) = @_;
724 (defined $method_name && $method_name)
725 || confess "You must define a method name";
727 return $self->get_method_map->{$method_name};
731 my ($self, $method_name) = @_;
732 (defined $method_name && $method_name)
733 || confess "You must define a method name";
735 my $removed_method = delete $self->get_method_map->{$method_name};
737 $self->remove_package_symbol(
738 { sigil => '&', type => 'CODE', name => $method_name }
741 $removed_method->detach_from_class if $removed_method;
743 $self->update_package_cache_flag; # still valid, since we just removed the method from the map
745 return $removed_method;
748 sub get_method_list {
750 keys %{$self->get_method_map};
753 sub find_method_by_name {
754 my ($self, $method_name) = @_;
755 (defined $method_name && $method_name)
756 || confess "You must define a method name to find";
757 foreach my $class ($self->linearized_isa) {
758 # fetch the meta-class ...
759 my $meta = $self->initialize($class);
760 return $meta->get_method($method_name)
761 if $meta->has_method($method_name);
766 sub get_all_methods {
768 my %methods = map { %{ $self->initialize($_)->get_method_map } } reverse $self->linearized_isa;
769 return values %methods;
772 sub compute_all_applicable_methods {
773 Carp::cluck('The compute_all_applicable_methods method is deprecated.'
774 . " Use get_all_methods instead.\n");
779 class => $_->package_name,
780 code => $_, # sigh, overloading
782 } shift->get_all_methods(@_);
785 sub get_all_method_names {
788 grep { $uniq{$_}++ == 0 } map { $_->name } $self->get_all_methods;
791 sub find_all_methods_by_name {
792 my ($self, $method_name) = @_;
793 (defined $method_name && $method_name)
794 || confess "You must define a method name to find";
796 foreach my $class ($self->linearized_isa) {
797 # fetch the meta-class ...
798 my $meta = $self->initialize($class);
800 name => $method_name,
802 code => $meta->get_method($method_name)
803 } if $meta->has_method($method_name);
808 sub find_next_method_by_name {
809 my ($self, $method_name) = @_;
810 (defined $method_name && $method_name)
811 || confess "You must define a method name to find";
812 my @cpl = $self->linearized_isa;
813 shift @cpl; # discard ourselves
814 foreach my $class (@cpl) {
815 # fetch the meta-class ...
816 my $meta = $self->initialize($class);
817 return $meta->get_method($method_name)
818 if $meta->has_method($method_name);
827 # either we have an attribute object already
828 # or we need to create one from the args provided
829 my $attribute = blessed($_[0]) ? $_[0] : $self->attribute_metaclass->new(@_);
830 # make sure it is derived from the correct type though
831 ($attribute->isa('Class::MOP::Attribute'))
832 || confess "Your attribute must be an instance of Class::MOP::Attribute (or a subclass)";
834 # first we attach our new attribute
835 # because it might need certain information
836 # about the class which it is attached to
837 $attribute->attach_to_class($self);
839 # then we remove attributes of a conflicting
840 # name here so that we can properly detach
841 # the old attr object, and remove any
842 # accessors it would have generated
843 if ( $self->has_attribute($attribute->name) ) {
844 $self->remove_attribute($attribute->name);
846 $self->invalidate_meta_instances();
849 # get our count of previously inserted attributes and
850 # increment by one so this attribute knows its order
851 my $order = (scalar keys %{$self->get_attribute_map}) - 1;
852 $attribute->_set_insertion_order($order + 1);
854 # then onto installing the new accessors
855 $self->get_attribute_map->{$attribute->name} = $attribute;
857 # invalidate package flag here
858 my $e = do { local $@; eval { $attribute->install_accessors() }; $@ };
860 $self->remove_attribute($attribute->name);
867 sub update_meta_instance_dependencies {
870 if ( $self->{meta_instance_dependencies} ) {
871 return $self->add_meta_instance_dependencies;
875 sub add_meta_instance_dependencies {
878 $self->remove_meta_instance_dependencies;
880 my @attrs = $self->get_all_attributes();
883 my @classes = grep { not $seen{$_->name}++ } map { $_->associated_class } @attrs;
885 foreach my $class ( @classes ) {
886 $class->add_dependent_meta_instance($self);
889 $self->{meta_instance_dependencies} = \@classes;
892 sub remove_meta_instance_dependencies {
895 if ( my $classes = delete $self->{meta_instance_dependencies} ) {
896 foreach my $class ( @$classes ) {
897 $class->remove_dependent_meta_instance($self);
907 sub add_dependent_meta_instance {
908 my ( $self, $metaclass ) = @_;
909 push @{ $self->{dependent_meta_instances} }, $metaclass;
912 sub remove_dependent_meta_instance {
913 my ( $self, $metaclass ) = @_;
914 my $name = $metaclass->name;
915 @$_ = grep { $_->name ne $name } @$_ for $self->{dependent_meta_instances};
918 sub invalidate_meta_instances {
920 $_->invalidate_meta_instance() for $self, @{ $self->{dependent_meta_instances} };
923 sub invalidate_meta_instance {
925 undef $self->{_meta_instance};
929 my ($self, $attribute_name) = @_;
930 (defined $attribute_name && $attribute_name)
931 || confess "You must define an attribute name";
932 exists $self->get_attribute_map->{$attribute_name};
936 my ($self, $attribute_name) = @_;
937 (defined $attribute_name && $attribute_name)
938 || confess "You must define an attribute name";
939 return $self->get_attribute_map->{$attribute_name}
941 # this will return undef anyway, so no need ...
942 # if $self->has_attribute($attribute_name);
946 sub remove_attribute {
947 my ($self, $attribute_name) = @_;
948 (defined $attribute_name && $attribute_name)
949 || confess "You must define an attribute name";
950 my $removed_attribute = $self->get_attribute_map->{$attribute_name};
951 return unless defined $removed_attribute;
952 delete $self->get_attribute_map->{$attribute_name};
953 $self->invalidate_meta_instances();
954 $removed_attribute->remove_accessors();
955 $removed_attribute->detach_from_class();
956 return $removed_attribute;
959 sub get_attribute_list {
961 keys %{$self->get_attribute_map};
964 sub get_all_attributes {
966 my %attrs = map { %{ $self->initialize($_)->get_attribute_map } } reverse $self->linearized_isa;
967 return values %attrs;
970 sub compute_all_applicable_attributes {
971 Carp::cluck('The compute_all_applicable_attributes method has been deprecated.'
972 . " Use get_all_attributes instead.\n");
974 shift->get_all_attributes(@_);
977 sub find_attribute_by_name {
978 my ($self, $attr_name) = @_;
979 foreach my $class ($self->linearized_isa) {
980 # fetch the meta-class ...
981 my $meta = $self->initialize($class);
982 return $meta->get_attribute($attr_name)
983 if $meta->has_attribute($attr_name);
988 # check if we can reinitialize
992 # if any local attr is defined
993 return if $self->get_attribute_list;
995 # or any non-declared methods
996 if ( my @methods = values %{ $self->get_method_map } ) {
997 my $metaclass = $self->method_metaclass;
998 foreach my $method ( @methods ) {
999 return if $method->isa("Class::MOP::Method::Generated");
1000 # FIXME do we need to enforce this too? return unless $method->isa($metaclass);
1009 sub is_mutable { 1 }
1010 sub is_immutable { 0 }
1011 sub immutable_transformer { return }
1013 sub _immutable_options {
1014 my ( $self, @args ) = @_;
1017 inline_accessors => 1,
1018 inline_constructor => 1,
1019 inline_destructor => 0,
1021 immutable_trait => $self->immutable_trait,
1022 constructor_name => $self->constructor_name,
1023 constructor_class => $self->constructor_class,
1024 destructor_class => $self->destructor_class,
1029 sub make_immutable {
1030 my ( $self, @args ) = @_;
1032 if ( $self->is_mutable ) {
1033 $self->_initialize_immutable( $self->_immutable_options(@args) );
1034 $self->_rebless_as_immutable(@args);
1045 if ( $self->is_immutable ) {
1046 my @args = $self->immutable_options;
1047 $self->_rebless_as_mutable();
1048 $self->_remove_inlined_code(@args);
1049 delete $self->{__immutable};
1057 sub _rebless_as_immutable {
1058 my ( $self, @args ) = @_;
1060 $self->{__immutable}{original_class} = ref $self;
1062 bless $self => $self->_immutable_metaclass(@args);
1065 sub _immutable_metaclass {
1066 my ( $self, %args ) = @_;
1068 if ( my $class = $args{immutable_metaclass} ) {
1072 my $trait = $args{immutable_trait} = $self->immutable_trait
1073 || confess "no immutable trait specified for $self";
1075 my $meta_attr = $self->meta->find_attribute_by_name("immutable_trait");
1079 if ( $meta_attr and $trait eq $meta_attr->default ) {
1081 # if the trait is the same as the default we try and pick a predictable
1082 # name for the immutable metaclass
1083 $class_name = "Class::MOP::Class::Immutable::" . ref($self);
1087 = join( "::", "Class::MOP::Class::Immutable::CustomTrait", $trait,
1088 "ForMetaClass", ref($self) );
1091 if ( Class::MOP::is_class_loaded($class_name) ) {
1092 if ( $class_name->isa($trait) ) {
1097 "$class_name is already defined but does not inherit $trait";
1101 my @super = ( $trait, ref($self) );
1103 my $meta = Class::MOP::Class->initialize($class_name);
1104 $meta->superclasses(@super);
1106 $meta->make_immutable;
1112 sub _remove_inlined_code {
1115 $self->remove_method( $_->name ) for $self->_inlined_methods;
1117 delete $self->{__immutable}{inlined_methods};
1120 sub _inlined_methods { @{ $_[0]{__immutable}{inlined_methods} || [] } }
1122 sub _add_inlined_method {
1123 my ( $self, $method ) = @_;
1125 push @{ $self->{__immutable}{inlined_methods} ||= [] }, $method;
1128 sub _initialize_immutable {
1129 my ( $self, %args ) = @_;
1131 $self->{__immutable}{options} = \%args;
1132 $self->_install_inlined_code(%args);
1135 sub _install_inlined_code {
1136 my ( $self, %args ) = @_;
1139 $self->_inline_accessors(%args) if $args{inline_accessors};
1140 $self->_inline_constructor(%args) if $args{inline_constructor};
1141 $self->_inline_destructor(%args) if $args{inline_destructor};
1144 sub _rebless_as_mutable {
1147 bless $self, $self->get_mutable_metaclass_name;
1152 sub _inline_accessors {
1155 foreach my $attr_name ( $self->get_attribute_list ) {
1156 $self->get_attribute($attr_name)->install_accessors(1);
1160 sub _inline_constructor {
1161 my ( $self, %args ) = @_;
1163 my $name = $args{constructor_name};
1165 if ( $self->has_method($name) && !$args{replace_constructor} ) {
1166 my $class = $self->name;
1167 warn "Not inlining a constructor for $class since it defines"
1168 . " its own constructor.\n"
1169 . "If you are certain you don't need to inline your"
1170 . " constructor, specify inline_constructor => 0 in your"
1171 . " call to $class->meta->make_immutable\n";
1175 my $constructor_class = $args{constructor_class};
1177 Class::MOP::load_class($constructor_class);
1179 my $constructor = $constructor_class->new(
1183 package_name => $self->name,
1187 if ( $args{replace_constructor} or $constructor->can_be_inlined ) {
1188 $self->add_method( $name => $constructor );
1189 $self->_add_inlined_method($constructor);
1193 sub _inline_destructor {
1194 my ( $self, %args ) = @_;
1196 ( exists $args{destructor_class} && defined $args{destructor_class} )
1197 || confess "The 'inline_destructor' option is present, but "
1198 . "no destructor class was specified";
1200 if ( $self->has_method('DESTROY') && ! $args{replace_destructor} ) {
1201 my $class = $self->name;
1202 warn "Not inlining a destructor for $class since it defines"
1203 . " its own destructor.\n";
1207 my $destructor_class = $args{destructor_class};
1209 Class::MOP::load_class($destructor_class);
1211 return unless $destructor_class->is_needed($self);
1213 my $destructor = $destructor_class->new(
1216 package_name => $self->name,
1220 if ( $args{replace_destructor} or $destructor->can_be_inlined ) {
1221 $self->add_method( 'DESTROY' => $destructor );
1222 $self->_add_inlined_method($destructor);
1234 Class::MOP::Class - Class Meta Object
1238 # assuming that class Foo
1239 # has been defined, you can
1241 # use this for introspection ...
1243 # add a method to Foo ...
1244 Foo->meta->add_method( 'bar' => sub {...} )
1246 # get a list of all the classes searched
1247 # the method dispatcher in the correct order
1248 Foo->meta->class_precedence_list()
1250 # remove a method from Foo
1251 Foo->meta->remove_method('bar');
1253 # or use this to actually create classes ...
1255 Class::MOP::Class->create(
1258 superclasses => ['Foo'],
1260 Class::MOP::Attribute->new('$bar'),
1261 Class::MOP::Attribute->new('$baz'),
1264 calculate_bar => sub {...},
1265 construct_baz => sub {...}
1272 The Class Protocol is the largest and most complex part of the
1273 Class::MOP meta-object protocol. It controls the introspection and
1274 manipulation of Perl 5 classes, and it can create them as well. The
1275 best way to understand what this module can do, is to read the
1276 documentation for each of its methods.
1280 C<Class::MOP::Class> is a subclass of L<Class::MOP::Module>.
1284 =head2 Class construction
1286 These methods all create new C<Class::MOP::Class> objects. These
1287 objects can represent existing classes, or they can be used to create
1288 new classes from scratch.
1290 The metaclass object for a given class is a singleton. If you attempt
1291 to create a metaclass for the same class twice, you will just get the
1296 =item B<< Class::MOP::Class->create($package_name, %options) >>
1298 This method creates a new C<Class::MOP::Class> object with the given
1299 package name. It accepts a number of options.
1305 An optional version number for the newly created package.
1309 An optional authority for the newly created package.
1311 =item * superclasses
1313 An optional array reference of superclass names.
1317 An optional hash reference of methods for the class. The keys of the
1318 hash reference are method names, and values are subroutine references.
1322 An optional array reference of attributes.
1324 An attribute can be passed as an existing L<Class::MOP::Attribute>
1325 object, I<or> or as a hash reference of options which will be passed
1326 to the attribute metaclass's constructor.
1330 =item B<< Class::MOP::Class->create_anon_class(%options) >>
1332 This method works just like C<< Class::MOP::Class->create >> but it
1333 creates an "anonymous" class. In fact, the class does have a name, but
1334 that name is a unique name generated internally by this module.
1336 It accepts the same C<superclasses>, C<methods>, and C<attributes>
1337 parameters that C<create> accepts.
1339 Anonymous classes are destroyed once the metaclass they are attached
1340 to goes out of scope, and will be removed from Perl's internal symbol
1343 All instances of an anonymous class keep a special reference to the
1344 metaclass object, which prevents the metaclass from going out of scope
1345 while any instances exist.
1347 This only works if the instance if based on a hash reference, however.
1349 =item B<< Class::MOP::Class->initialize($package_name, %options) >>
1351 This method will initialize a C<Class::MOP::Class> object for the
1352 named package. Unlike C<create>, this method I<will not> create a new
1355 The purpose of this method is to retrieve a C<Class::MOP::Class>
1356 object for introspecting an existing class.
1358 If an existing C<Class::MOP::Class> object exists for the named
1359 package, it will be returned, and any options provided will be
1362 If the object does not yet exist, it will be created.
1364 The valid options that can be passed to this method are
1365 C<attribute_metaclass>, C<method_metaclass>,
1366 C<wrapped_method_metaclass>, and C<instance_metaclass>. These are all
1367 optional, and default to the appropriate class in the C<Class::MOP>
1372 =head2 Object instance construction and cloning
1374 These methods are all related to creating and/or cloning object
1379 =item B<< $metaclass->clone_object($instance, %params) >>
1381 This method clones an existing object instance. Any parameters you
1382 provide are will override existing attribute values in the object.
1384 This is a convenience method for cloning an object instance, then
1385 blessing it into the appropriate package.
1387 You could implement a clone method in your class, using this method:
1390 my ($self, %params) = @_;
1391 $self->meta->clone_object($self, %params);
1394 =item B<< $metaclass->rebless_instance($instance, %params) >>
1396 This method changes the class of C<$instance> to the metaclass's class.
1398 You can only rebless an instance into a subclass of its current
1399 class. If you pass any additional parameters, these will be treated
1400 like constructor parameters and used to initialize the object's
1401 attributes. Any existing attributes that are already set will be
1404 Before reblessing the instance, this method will call
1405 C<rebless_instance_away> on the instance's current metaclass. This method
1406 will be passed the instance, the new metaclass, and any parameters
1407 specified to C<rebless_instance>. By default, C<rebless_instance_away>
1408 does nothing; it is merely a hook.
1410 =item B<< $metaclass->new_object(%params) >>
1412 This method is used to create a new object of the metaclass's
1413 class. Any parameters you provide are used to initialize the
1414 instance's attributes.
1416 =item B<< $metaclass->instance_metaclass >>
1418 Returns the class name of the instance metaclass, see
1419 L<Class::MOP::Instance> for more information on the instance
1422 =item B<< $metaclass->get_meta_instance >>
1424 Returns an instance of the C<instance_metaclass> to be used in the
1425 construction of a new instance of the class.
1429 =head2 Informational predicates
1431 These are a few predicate methods for asking information about the
1436 =item B<< $metaclass->is_anon_class >>
1438 This returns true if the class was created by calling C<<
1439 Class::MOP::Class->create_anon_class >>.
1441 =item B<< $metaclass->is_mutable >>
1443 This returns true if the class is still mutable.
1445 =item B<< $metaclass->is_immutable >>
1447 This returns true if the class has been made immutable.
1449 =item B<< $metaclass->is_pristine >>
1451 A class is I<not> pristine if it has non-inherited attributes or if it
1452 has any generated methods.
1456 =head2 Inheritance Relationships
1460 =item B<< $metaclass->superclasses(@superclasses) >>
1462 This is a read-write accessor which represents the superclass
1463 relationships of the metaclass's class.
1465 This is basically sugar around getting and setting C<@ISA>.
1467 =item B<< $metaclass->class_precedence_list >>
1469 This returns a list of all of the class's ancestor classes. The
1470 classes are returned in method dispatch order.
1472 =item B<< $metaclass->linearized_isa >>
1474 This returns a list based on C<class_precedence_list> but with all
1477 =item B<< $metaclass->subclasses >>
1479 This returns a list of all subclasses for this class, even indirect
1482 =item B<< $metaclass->direct_subclasses >>
1484 This returns a list of immediate subclasses for this class, which does not
1485 include indirect subclasses.
1489 =head2 Method introspection and creation
1491 These methods allow you to introspect a class's methods, as well as
1492 add, remove, or change methods.
1494 Determining what is truly a method in a Perl 5 class requires some
1495 heuristics (aka guessing).
1497 Methods defined outside the package with a fully qualified name (C<sub
1498 Package::name { ... }>) will be included. Similarly, methods named
1499 with a fully qualified name using L<Sub::Name> are also included.
1501 However, we attempt to ignore imported functions.
1503 Ultimately, we are using heuristics to determine what truly is a
1504 method in a class, and these heuristics may get the wrong answer in
1505 some edge cases. However, for most "normal" cases the heuristics work
1510 =item B<< $metaclass->get_method($method_name) >>
1512 This will return a L<Class::MOP::Method> for the specified
1513 C<$method_name>. If the class does not have the specified method, it
1516 =item B<< $metaclass->has_method($method_name) >>
1518 Returns a boolean indicating whether or not the class defines the
1519 named method. It does not include methods inherited from parent
1522 =item B<< $metaclass->get_method_map >>
1524 Returns a hash reference representing the methods defined in this
1525 class. The keys are method names and the values are
1526 L<Class::MOP::Method> objects.
1528 =item B<< $metaclass->get_method_list >>
1530 This will return a list of method I<names> for all methods defined in
1533 =item B<< $metaclass->get_all_methods >>
1535 This will traverse the inheritance hierarchy and return a list of all
1536 the L<Class::MOP::Method> objects for this class and its parents.
1538 =item B<< $metaclass->find_method_by_name($method_name) >>
1540 This will return a L<Class::MOP::Method> for the specified
1541 C<$method_name>. If the class does not have the specified method, it
1544 Unlike C<get_method>, this method I<will> look for the named method in
1547 =item B<< $metaclass->get_all_method_names >>
1549 This will return a list of method I<names> for all of this class's
1550 methods, including inherited methods.
1552 =item B<< $metaclass->find_all_methods_by_name($method_name) >>
1554 This method looks for the named method in the class and all of its
1555 parents. It returns every matching method it finds in the inheritance
1556 tree, so it returns a list of methods.
1558 Each method is returned as a hash reference with three keys. The keys
1559 are C<name>, C<class>, and C<code>. The C<code> key has a
1560 L<Class::MOP::Method> object as its value.
1562 The list of methods is distinct.
1564 =item B<< $metaclass->find_next_method_by_name($method_name) >>
1566 This method returns the first method in any superclass matching the
1567 given name. It is effectively the method that C<SUPER::$method_name>
1570 =item B<< $metaclass->add_method($method_name, $method) >>
1572 This method takes a method name and a subroutine reference, and adds
1573 the method to the class.
1575 The subroutine reference can be a L<Class::MOP::Method>, and you are
1576 strongly encouraged to pass a meta method object instead of a code
1577 reference. If you do so, that object gets stored as part of the
1578 class's method map directly. If not, the meta information will have to
1579 be recreated later, and may be incorrect.
1581 If you provide a method object, this method will clone that object if
1582 the object's package name does not match the class name. This lets us
1583 track the original source of any methods added from other classes
1584 (notably Moose roles).
1586 =item B<< $metaclass->remove_method($method_name) >>
1588 Remove the named method from the class. This method returns the
1589 L<Class::MOP::Method> object for the method.
1591 =item B<< $metaclass->method_metaclass >>
1593 Returns the class name of the method metaclass, see
1594 L<Class::MOP::Method> for more information on the method metaclass.
1596 =item B<< $metaclass->wrapped_method_metaclass >>
1598 Returns the class name of the wrapped method metaclass, see
1599 L<Class::MOP::Method::Wrapped> for more information on the wrapped
1604 =head2 Attribute introspection and creation
1606 Because Perl 5 does not have a core concept of attributes in classes,
1607 we can only return information about attributes which have been added
1608 via this class's methods. We cannot discover information about
1609 attributes which are defined in terms of "regular" Perl 5 methods.
1613 =item B<< $metaclass->get_attribute($attribute_name) >>
1615 This will return a L<Class::MOP::Attribute> for the specified
1616 C<$attribute_name>. If the class does not have the specified
1617 attribute, it returns C<undef>.
1619 NOTE that get_attribute does not search superclasses, for
1620 that you need to use C<find_attribute_by_name>.
1622 =item B<< $metaclass->has_attribute($attribute_name) >>
1624 Returns a boolean indicating whether or not the class defines the
1625 named attribute. It does not include attributes inherited from parent
1628 =item B<< $metaclass->get_attribute_map >>
1630 Returns a hash reference representing the attributes defined in this
1631 class. The keys are attribute names and the values are
1632 L<Class::MOP::Attribute> objects.
1634 =item B<< $metaclass->get_attribute_list >>
1636 This will return a list of attributes I<names> for all attributes
1637 defined in this class.
1639 =item B<< $metaclass->get_all_attributes >>
1641 This will traverse the inheritance hierarchy and return a list of all
1642 the L<Class::MOP::Attribute> objects for this class and its parents.
1644 =item B<< $metaclass->find_attribute_by_name($attribute_name) >>
1646 This will return a L<Class::MOP::Attribute> for the specified
1647 C<$attribute_name>. If the class does not have the specified
1648 attribute, it returns C<undef>
1650 Unlike C<get_attribute>, this attribute I<will> look for the named
1651 attribute in superclasses.
1653 =item B<< $metaclass->add_attribute(...) >>
1655 This method accepts either an existing L<Class::MOP::Attribute>
1656 object, or parameters suitable for passing to that class's C<new>
1659 The attribute provided will be added to the class.
1661 Any accessor methods defined by the attribute will be added to the
1662 class when the attribute is added.
1664 If an attribute of the same name already exists, the old attribute
1665 will be removed first.
1667 =item B<< $metaclass->remove_attribute($attribute_name) >>
1669 This will remove the named attribute from the class, and
1670 L<Class::MOP::Attribute> object.
1672 Removing an attribute also removes any accessor methods defined by the
1675 However, note that removing an attribute will only affect I<future>
1676 object instances created for this class, not existing instances.
1678 =item B<< $metaclass->attribute_metaclass >>
1680 Returns the class name of the attribute metaclass for this class. By
1681 default, this is L<Class::MOP::Attribute>. for more information on
1685 =head2 Class Immutability
1687 Making a class immutable "freezes" the class definition. You can no
1688 longer call methods which alter the class, such as adding or removing
1689 methods or attributes.
1691 Making a class immutable lets us optimize the class by inlining some
1692 methods, and also allows us to optimize some methods on the metaclass
1695 The immutabilization system in L<Moose> takes much greater advantage
1696 of the inlining features than Class::MOP itself does.
1700 =item B<< $metaclass->make_immutable(%options) >>
1702 This method will create an immutable transformer and uses it to make
1703 the class and its metaclass object immutable.
1705 Details of how immutabilization works are in L<Class::MOP::Immutable>
1708 =item B<< $metaclass->make_mutable >>
1710 Calling this method reverse the immutabilization transformation.
1712 =item B<< $metaclass->immutable_transformer >>
1714 If the class has been made immutable previously, this returns the
1715 L<Class::MOP::Immutable> object that was created to do the
1718 If the class was never made immutable, this method will die.
1722 =head2 Method Modifiers
1724 Method modifiers are hooks which allow a method to be wrapped with
1725 I<before>, I<after> and I<around> method modifiers. Every time a
1726 method is called, it's modifiers are also called.
1728 A class can modify its own methods, as well as methods defined in
1731 =head3 How method modifiers work?
1733 Method modifiers work by wrapping the original method and then
1734 replacing it in the class's symbol table. The wrappers will handle
1735 calling all the modifiers in the appropriate order and preserving the
1736 calling context for the original method.
1738 The return values of C<before> and C<after> modifiers are
1739 ignored. This is because their purpose is B<not> to filter the input
1740 and output of the primary method (this is done with an I<around>
1743 This may seem like an odd restriction to some, but doing this allows
1744 for simple code to be added at the beginning or end of a method call
1745 without altering the function of the wrapped method or placing any
1746 extra responsibility on the code of the modifier.
1748 Of course if you have more complex needs, you can use the C<around>
1749 modifier which allows you to change both the parameters passed to the
1750 wrapped method, as well as its return value.
1752 Before and around modifiers are called in last-defined-first-called
1753 order, while after modifiers are called in first-defined-first-called
1754 order. So the call tree might looks something like this:
1766 =head3 What is the performance impact?
1768 Of course there is a performance cost associated with method
1769 modifiers, but we have made every effort to make that cost directly
1770 proportional to the number of modifier features you utilize.
1772 The wrapping method does it's best to B<only> do as much work as it
1773 absolutely needs to. In order to do this we have moved some of the
1774 performance costs to set-up time, where they are easier to amortize.
1776 All this said, our benchmarks have indicated the following:
1778 simple wrapper with no modifiers 100% slower
1779 simple wrapper with simple before modifier 400% slower
1780 simple wrapper with simple after modifier 450% slower
1781 simple wrapper with simple around modifier 500-550% slower
1782 simple wrapper with all 3 modifiers 1100% slower
1784 These numbers may seem daunting, but you must remember, every feature
1785 comes with some cost. To put things in perspective, just doing a
1786 simple C<AUTOLOAD> which does nothing but extract the name of the
1787 method called and return it costs about 400% over a normal method
1792 =item B<< $metaclass->add_before_method_modifier($method_name, $code) >>
1794 This wraps the specified method with the supplied subroutine
1795 reference. The modifier will be called as a method itself, and will
1796 receive the same arguments as are passed to the method.
1798 When the modifier exits, the wrapped method will be called.
1800 The return value of the modifier will be ignored.
1802 =item B<< $metaclass->add_after_method_modifier($method_name, $code) >>
1804 This wraps the specified method with the supplied subroutine
1805 reference. The modifier will be called as a method itself, and will
1806 receive the same arguments as are passed to the method.
1808 When the wrapped methods exits, the modifier will be called.
1810 The return value of the modifier will be ignored.
1812 =item B<< $metaclass->add_around_method_modifier($method_name, $code) >>
1814 This wraps the specified method with the supplied subroutine
1817 The first argument passed to the modifier will be a subroutine
1818 reference to the wrapped method. The second argument is the object,
1819 and after that come any arguments passed when the method is called.
1821 The around modifier can choose to call the original method, as well as
1822 what arguments to pass if it does so.
1824 The return value of the modifier is what will be seen by the caller.
1828 =head2 Introspection
1832 =item B<< Class::MOP::Class->meta >>
1834 This will return a L<Class::MOP::Class> instance for this class.
1836 It should also be noted that L<Class::MOP> will actually bootstrap
1837 this module by installing a number of attribute meta-objects into its
1844 Stevan Little E<lt>stevan@iinteractive.comE<gt>
1846 =head1 COPYRIGHT AND LICENSE
1848 Copyright 2006-2009 by Infinity Interactive, Inc.
1850 L<http://www.iinteractive.com>
1852 This library is free software; you can redistribute it and/or modify
1853 it under the same terms as Perl itself.