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} )
1197 || confess "The 'inline_destructor' option is present, but "
1198 . "no destructor class was specified";
1200 if ( $self->has_method('DESTROY') ) {
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 $self->add_method( 'DESTROY' => $destructor );
1222 $self->_add_inlined_method($destructor);
1233 Class::MOP::Class - Class Meta Object
1237 # assuming that class Foo
1238 # has been defined, you can
1240 # use this for introspection ...
1242 # add a method to Foo ...
1243 Foo->meta->add_method( 'bar' => sub {...} )
1245 # get a list of all the classes searched
1246 # the method dispatcher in the correct order
1247 Foo->meta->class_precedence_list()
1249 # remove a method from Foo
1250 Foo->meta->remove_method('bar');
1252 # or use this to actually create classes ...
1254 Class::MOP::Class->create(
1257 superclasses => ['Foo'],
1259 Class::MOP::Attribute->new('$bar'),
1260 Class::MOP::Attribute->new('$baz'),
1263 calculate_bar => sub {...},
1264 construct_baz => sub {...}
1271 The Class Protocol is the largest and most complex part of the
1272 Class::MOP meta-object protocol. It controls the introspection and
1273 manipulation of Perl 5 classes, and it can create them as well. The
1274 best way to understand what this module can do, is to read the
1275 documentation for each of its methods.
1279 C<Class::MOP::Class> is a subclass of L<Class::MOP::Module>.
1283 =head2 Class construction
1285 These methods all create new C<Class::MOP::Class> objects. These
1286 objects can represent existing classes, or they can be used to create
1287 new classes from scratch.
1289 The metaclass object for a given class is a singleton. If you attempt
1290 to create a metaclass for the same class twice, you will just get the
1295 =item B<< Class::MOP::Class->create($package_name, %options) >>
1297 This method creates a new C<Class::MOP::Class> object with the given
1298 package name. It accepts a number of options.
1304 An optional version number for the newly created package.
1308 An optional authority for the newly created package.
1310 =item * superclasses
1312 An optional array reference of superclass names.
1316 An optional hash reference of methods for the class. The keys of the
1317 hash reference are method names, and values are subroutine references.
1321 An optional array reference of attributes.
1323 An attribute can be passed as an existing L<Class::MOP::Attribute>
1324 object, I<or> or as a hash reference of options which will be passed
1325 to the attribute metaclass's constructor.
1329 =item B<< Class::MOP::Class->create_anon_class(%options) >>
1331 This method works just like C<< Class::MOP::Class->create >> but it
1332 creates an "anonymous" class. In fact, the class does have a name, but
1333 that name is a unique name generated internally by this module.
1335 It accepts the same C<superclasses>, C<methods>, and C<attributes>
1336 parameters that C<create> accepts.
1338 Anonymous classes are destroyed once the metaclass they are attached
1339 to goes out of scope, and will be removed from Perl's internal symbol
1342 All instances of an anonymous class keep a special reference to the
1343 metaclass object, which prevents the metaclass from going out of scope
1344 while any instances exist.
1346 This only works if the instance if based on a hash reference, however.
1348 =item B<< Class::MOP::Class->initialize($package_name, %options) >>
1350 This method will initialize a C<Class::MOP::Class> object for the
1351 named package. Unlike C<create>, this method I<will not> create a new
1354 The purpose of this method is to retrieve a C<Class::MOP::Class>
1355 object for introspecting an existing class.
1357 If an existing C<Class::MOP::Class> object exists for the named
1358 package, it will be returned, and any options provided will be
1361 If the object does not yet exist, it will be created.
1363 The valid options that can be passed to this method are
1364 C<attribute_metaclass>, C<method_metaclass>,
1365 C<wrapped_method_metaclass>, and C<instance_metaclass>. These are all
1366 optional, and default to the appropriate class in the C<Class::MOP>
1371 =head2 Object instance construction and cloning
1373 These methods are all related to creating and/or cloning object
1378 =item B<< $metaclass->clone_object($instance, %params) >>
1380 This method clones an existing object instance. Any parameters you
1381 provide are will override existing attribute values in the object.
1383 This is a convenience method for cloning an object instance, then
1384 blessing it into the appropriate package.
1386 You could implement a clone method in your class, using this method:
1389 my ($self, %params) = @_;
1390 $self->meta->clone_object($self, %params);
1393 =item B<< $metaclass->rebless_instance($instance, %params) >>
1395 This method changes the class of C<$instance> to the metaclass's class.
1397 You can only rebless an instance into a subclass of its current
1398 class. If you pass any additional parameters, these will be treated
1399 like constructor parameters and used to initialize the object's
1400 attributes. Any existing attributes that are already set will be
1403 Before reblessing the instance, this method will call
1404 C<rebless_instance_away> on the instance's current metaclass. This method
1405 will be passed the instance, the new metaclass, and any parameters
1406 specified to C<rebless_instance>. By default, C<rebless_instance_away>
1407 does nothing; it is merely a hook.
1409 =item B<< $metaclass->new_object(%params) >>
1411 This method is used to create a new object of the metaclass's
1412 class. Any parameters you provide are used to initialize the
1413 instance's attributes.
1415 =item B<< $metaclass->instance_metaclass >>
1417 Returns the class name of the instance metaclass, see
1418 L<Class::MOP::Instance> for more information on the instance
1421 =item B<< $metaclass->get_meta_instance >>
1423 Returns an instance of the C<instance_metaclass> to be used in the
1424 construction of a new instance of the class.
1428 =head2 Informational predicates
1430 These are a few predicate methods for asking information about the
1435 =item B<< $metaclass->is_anon_class >>
1437 This returns true if the class was created by calling C<<
1438 Class::MOP::Class->create_anon_class >>.
1440 =item B<< $metaclass->is_mutable >>
1442 This returns true if the class is still mutable.
1444 =item B<< $metaclass->is_immutable >>
1446 This returns true if the class has been made immutable.
1448 =item B<< $metaclass->is_pristine >>
1450 A class is I<not> pristine if it has non-inherited attributes or if it
1451 has any generated methods.
1455 =head2 Inheritance Relationships
1459 =item B<< $metaclass->superclasses(@superclasses) >>
1461 This is a read-write accessor which represents the superclass
1462 relationships of the metaclass's class.
1464 This is basically sugar around getting and setting C<@ISA>.
1466 =item B<< $metaclass->class_precedence_list >>
1468 This returns a list of all of the class's ancestor classes. The
1469 classes are returned in method dispatch order.
1471 =item B<< $metaclass->linearized_isa >>
1473 This returns a list based on C<class_precedence_list> but with all
1476 =item B<< $metaclass->subclasses >>
1478 This returns a list of all subclasses for this class, even indirect
1481 =item B<< $metaclass->direct_subclasses >>
1483 This returns a list of immediate subclasses for this class, which does not
1484 include indirect subclasses.
1488 =head2 Method introspection and creation
1490 These methods allow you to introspect a class's methods, as well as
1491 add, remove, or change methods.
1493 Determining what is truly a method in a Perl 5 class requires some
1494 heuristics (aka guessing).
1496 Methods defined outside the package with a fully qualified name (C<sub
1497 Package::name { ... }>) will be included. Similarly, methods named
1498 with a fully qualified name using L<Sub::Name> are also included.
1500 However, we attempt to ignore imported functions.
1502 Ultimately, we are using heuristics to determine what truly is a
1503 method in a class, and these heuristics may get the wrong answer in
1504 some edge cases. However, for most "normal" cases the heuristics work
1509 =item B<< $metaclass->get_method($method_name) >>
1511 This will return a L<Class::MOP::Method> for the specified
1512 C<$method_name>. If the class does not have the specified method, it
1515 =item B<< $metaclass->has_method($method_name) >>
1517 Returns a boolean indicating whether or not the class defines the
1518 named method. It does not include methods inherited from parent
1521 =item B<< $metaclass->get_method_map >>
1523 Returns a hash reference representing the methods defined in this
1524 class. The keys are method names and the values are
1525 L<Class::MOP::Method> objects.
1527 =item B<< $metaclass->get_method_list >>
1529 This will return a list of method I<names> for all methods defined in
1532 =item B<< $metaclass->get_all_methods >>
1534 This will traverse the inheritance hierarchy and return a list of all
1535 the L<Class::MOP::Method> objects for this class and its parents.
1537 =item B<< $metaclass->find_method_by_name($method_name) >>
1539 This will return a L<Class::MOP::Method> for the specified
1540 C<$method_name>. If the class does not have the specified method, it
1543 Unlike C<get_method>, this method I<will> look for the named method in
1546 =item B<< $metaclass->get_all_method_names >>
1548 This will return a list of method I<names> for all of this class's
1549 methods, including inherited methods.
1551 =item B<< $metaclass->find_all_methods_by_name($method_name) >>
1553 This method looks for the named method in the class and all of its
1554 parents. It returns every matching method it finds in the inheritance
1555 tree, so it returns a list of methods.
1557 Each method is returned as a hash reference with three keys. The keys
1558 are C<name>, C<class>, and C<code>. The C<code> key has a
1559 L<Class::MOP::Method> object as its value.
1561 The list of methods is distinct.
1563 =item B<< $metaclass->find_next_method_by_name($method_name) >>
1565 This method returns the first method in any superclass matching the
1566 given name. It is effectively the method that C<SUPER::$method_name>
1569 =item B<< $metaclass->add_method($method_name, $method) >>
1571 This method takes a method name and a subroutine reference, and adds
1572 the method to the class.
1574 The subroutine reference can be a L<Class::MOP::Method>, and you are
1575 strongly encouraged to pass a meta method object instead of a code
1576 reference. If you do so, that object gets stored as part of the
1577 class's method map directly. If not, the meta information will have to
1578 be recreated later, and may be incorrect.
1580 If you provide a method object, this method will clone that object if
1581 the object's package name does not match the class name. This lets us
1582 track the original source of any methods added from other classes
1583 (notably Moose roles).
1585 =item B<< $metaclass->remove_method($method_name) >>
1587 Remove the named method from the class. This method returns the
1588 L<Class::MOP::Method> object for the method.
1590 =item B<< $metaclass->method_metaclass >>
1592 Returns the class name of the method metaclass, see
1593 L<Class::MOP::Method> for more information on the method metaclass.
1595 =item B<< $metaclass->wrapped_method_metaclass >>
1597 Returns the class name of the wrapped method metaclass, see
1598 L<Class::MOP::Method::Wrapped> for more information on the wrapped
1603 =head2 Attribute introspection and creation
1605 Because Perl 5 does not have a core concept of attributes in classes,
1606 we can only return information about attributes which have been added
1607 via this class's methods. We cannot discover information about
1608 attributes which are defined in terms of "regular" Perl 5 methods.
1612 =item B<< $metaclass->get_attribute($attribute_name) >>
1614 This will return a L<Class::MOP::Attribute> for the specified
1615 C<$attribute_name>. If the class does not have the specified
1616 attribute, it returns C<undef>.
1618 NOTE that get_attribute does not search superclasses, for
1619 that you need to use C<find_attribute_by_name>.
1621 =item B<< $metaclass->has_attribute($attribute_name) >>
1623 Returns a boolean indicating whether or not the class defines the
1624 named attribute. It does not include attributes inherited from parent
1627 =item B<< $metaclass->get_attribute_map >>
1629 Returns a hash reference representing the attributes defined in this
1630 class. The keys are attribute names and the values are
1631 L<Class::MOP::Attribute> objects.
1633 =item B<< $metaclass->get_attribute_list >>
1635 This will return a list of attributes I<names> for all attributes
1636 defined in this class.
1638 =item B<< $metaclass->get_all_attributes >>
1640 This will traverse the inheritance hierarchy and return a list of all
1641 the L<Class::MOP::Attribute> objects for this class and its parents.
1643 =item B<< $metaclass->find_attribute_by_name($attribute_name) >>
1645 This will return a L<Class::MOP::Attribute> for the specified
1646 C<$attribute_name>. If the class does not have the specified
1647 attribute, it returns C<undef>
1649 Unlike C<get_attribute>, this attribute I<will> look for the named
1650 attribute in superclasses.
1652 =item B<< $metaclass->add_attribute(...) >>
1654 This method accepts either an existing L<Class::MOP::Attribute>
1655 object, or parameters suitable for passing to that class's C<new>
1658 The attribute provided will be added to the class.
1660 Any accessor methods defined by the attribute will be added to the
1661 class when the attribute is added.
1663 If an attribute of the same name already exists, the old attribute
1664 will be removed first.
1666 =item B<< $metaclass->remove_attribute($attribute_name) >>
1668 This will remove the named attribute from the class, and
1669 L<Class::MOP::Attribute> object.
1671 Removing an attribute also removes any accessor methods defined by the
1674 However, note that removing an attribute will only affect I<future>
1675 object instances created for this class, not existing instances.
1677 =item B<< $metaclass->attribute_metaclass >>
1679 Returns the class name of the attribute metaclass for this class. By
1680 default, this is L<Class::MOP::Attribute>. for more information on
1684 =head2 Class Immutability
1686 Making a class immutable "freezes" the class definition. You can no
1687 longer call methods which alter the class, such as adding or removing
1688 methods or attributes.
1690 Making a class immutable lets us optimize the class by inlining some
1691 methods, and also allows us to optimize some methods on the metaclass
1694 The immutabilization system in L<Moose> takes much greater advantage
1695 of the inlining features than Class::MOP itself does.
1699 =item B<< $metaclass->make_immutable(%options) >>
1701 This method will create an immutable transformer and uses it to make
1702 the class and its metaclass object immutable.
1704 Details of how immutabilization works are in L<Class::MOP::Immutable>
1707 =item B<< $metaclass->make_mutable >>
1709 Calling this method reverse the immutabilization transformation.
1711 =item B<< $metaclass->immutable_transformer >>
1713 If the class has been made immutable previously, this returns the
1714 L<Class::MOP::Immutable> object that was created to do the
1717 If the class was never made immutable, this method will die.
1721 =head2 Method Modifiers
1723 Method modifiers are hooks which allow a method to be wrapped with
1724 I<before>, I<after> and I<around> method modifiers. Every time a
1725 method is called, it's modifiers are also called.
1727 A class can modify its own methods, as well as methods defined in
1730 =head3 How method modifiers work?
1732 Method modifiers work by wrapping the original method and then
1733 replacing it in the class's symbol table. The wrappers will handle
1734 calling all the modifiers in the appropriate order and preserving the
1735 calling context for the original method.
1737 The return values of C<before> and C<after> modifiers are
1738 ignored. This is because their purpose is B<not> to filter the input
1739 and output of the primary method (this is done with an I<around>
1742 This may seem like an odd restriction to some, but doing this allows
1743 for simple code to be added at the beginning or end of a method call
1744 without altering the function of the wrapped method or placing any
1745 extra responsibility on the code of the modifier.
1747 Of course if you have more complex needs, you can use the C<around>
1748 modifier which allows you to change both the parameters passed to the
1749 wrapped method, as well as its return value.
1751 Before and around modifiers are called in last-defined-first-called
1752 order, while after modifiers are called in first-defined-first-called
1753 order. So the call tree might looks something like this:
1765 =head3 What is the performance impact?
1767 Of course there is a performance cost associated with method
1768 modifiers, but we have made every effort to make that cost directly
1769 proportional to the number of modifier features you utilize.
1771 The wrapping method does it's best to B<only> do as much work as it
1772 absolutely needs to. In order to do this we have moved some of the
1773 performance costs to set-up time, where they are easier to amortize.
1775 All this said, our benchmarks have indicated the following:
1777 simple wrapper with no modifiers 100% slower
1778 simple wrapper with simple before modifier 400% slower
1779 simple wrapper with simple after modifier 450% slower
1780 simple wrapper with simple around modifier 500-550% slower
1781 simple wrapper with all 3 modifiers 1100% slower
1783 These numbers may seem daunting, but you must remember, every feature
1784 comes with some cost. To put things in perspective, just doing a
1785 simple C<AUTOLOAD> which does nothing but extract the name of the
1786 method called and return it costs about 400% over a normal method
1791 =item B<< $metaclass->add_before_method_modifier($method_name, $code) >>
1793 This wraps the specified method with the supplied subroutine
1794 reference. The modifier will be called as a method itself, and will
1795 receive the same arguments as are passed to the method.
1797 When the modifier exits, the wrapped method will be called.
1799 The return value of the modifier will be ignored.
1801 =item B<< $metaclass->add_after_method_modifier($method_name, $code) >>
1803 This wraps the specified method with the supplied subroutine
1804 reference. The modifier will be called as a method itself, and will
1805 receive the same arguments as are passed to the method.
1807 When the wrapped methods exits, the modifier will be called.
1809 The return value of the modifier will be ignored.
1811 =item B<< $metaclass->add_around_method_modifier($method_name, $code) >>
1813 This wraps the specified method with the supplied subroutine
1816 The first argument passed to the modifier will be a subroutine
1817 reference to the wrapped method. The second argument is the object,
1818 and after that come any arguments passed when the method is called.
1820 The around modifier can choose to call the original method, as well as
1821 what arguments to pass if it does so.
1823 The return value of the modifier is what will be seen by the caller.
1827 =head2 Introspection
1831 =item B<< Class::MOP::Class->meta >>
1833 This will return a L<Class::MOP::Class> instance for this class.
1835 It should also be noted that L<Class::MOP> will actually bootstrap
1836 this module by installing a number of attribute meta-objects into its
1843 Stevan Little E<lt>stevan@iinteractive.comE<gt>
1845 =head1 COPYRIGHT AND LICENSE
1847 Copyright 2006-2009 by Infinity Interactive, Inc.
1849 L<http://www.iinteractive.com>
1851 This library is free software; you can redistribute it and/or modify
1852 it under the same terms as Perl itself.