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 = '0.84';
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 $self->update_meta_instance_dependencies();
522 @{$self->get_package_symbol($var_spec)};
527 my $super_class = $self->name;
529 return @{ $super_class->mro::get_isarev() };
532 sub direct_subclasses {
534 my $super_class = $self->name;
539 } Class::MOP::Class->initialize($_)->superclasses
544 return @{ mro::get_linear_isa( (shift)->name ) };
547 sub class_precedence_list {
549 my $name = $self->name;
551 unless (Class::MOP::IS_RUNNING_ON_5_10()) {
553 # We need to check for circular inheritance here
554 # if we are are not on 5.10, cause 5.8 detects it
555 # late. This will do nothing if all is well, and
556 # blow up otherwise. Yes, it's an ugly hack, better
557 # suggestions are welcome.
559 ($name || return)->isa('This is a test for circular inheritance')
562 # if our mro is c3, we can
563 # just grab the linear_isa
564 if (mro::get_mro($name) eq 'c3') {
565 return @{ mro::get_linear_isa($name) }
569 # we can't grab the linear_isa for dfs
570 # since it has all the duplicates
575 $self->initialize($_)->class_precedence_list()
576 } $self->superclasses()
583 sub wrap_method_body {
584 my ( $self, %args ) = @_;
586 ('CODE' eq ref $args{body})
587 || confess "Your code block must be a CODE reference";
589 $self->method_metaclass->wrap(
590 package_name => $self->name,
596 my ($self, $method_name, $method) = @_;
597 (defined $method_name && $method_name)
598 || confess "You must define a method name";
601 if (blessed($method)) {
602 $body = $method->body;
603 if ($method->package_name ne $self->name) {
604 $method = $method->clone(
605 package_name => $self->name,
607 ) if $method->can('clone');
612 $method = $self->wrap_method_body( body => $body, name => $method_name );
615 $method->attach_to_class($self);
617 # This used to call get_method_map, which meant we would build all
618 # the method objects for the class just because we added one
619 # method. This is hackier, but quicker too.
620 $self->{methods}{$method_name} = $method;
622 my ( $current_package, $current_name ) = Class::MOP::get_code_info($body);
624 if ( $current_name eq '__ANON__' ) {
625 my $full_method_name = ($self->name . '::' . $method_name);
626 subname($full_method_name => $body);
629 $self->add_package_symbol(
630 { sigil => '&', type => 'CODE', name => $method_name },
636 my $fetch_and_prepare_method = sub {
637 my ($self, $method_name) = @_;
638 my $wrapped_metaclass = $self->wrapped_method_metaclass;
640 my $method = $self->get_method($method_name);
641 # if we dont have local ...
643 # try to find the next method
644 $method = $self->find_next_method_by_name($method_name);
645 # die if it does not exist
647 || confess "The method '$method_name' was not found in the inheritance hierarchy for " . $self->name;
648 # and now make sure to wrap it
649 # even if it is already wrapped
650 # because we need a new sub ref
651 $method = $wrapped_metaclass->wrap($method);
654 # now make sure we wrap it properly
655 $method = $wrapped_metaclass->wrap($method)
656 unless $method->isa($wrapped_metaclass);
658 $self->add_method($method_name => $method);
662 sub add_before_method_modifier {
663 my ($self, $method_name, $method_modifier) = @_;
664 (defined $method_name && $method_name)
665 || confess "You must pass in a method name";
666 my $method = $fetch_and_prepare_method->($self, $method_name);
667 $method->add_before_modifier(
668 subname(':before' => $method_modifier)
672 sub add_after_method_modifier {
673 my ($self, $method_name, $method_modifier) = @_;
674 (defined $method_name && $method_name)
675 || confess "You must pass in a method name";
676 my $method = $fetch_and_prepare_method->($self, $method_name);
677 $method->add_after_modifier(
678 subname(':after' => $method_modifier)
682 sub add_around_method_modifier {
683 my ($self, $method_name, $method_modifier) = @_;
684 (defined $method_name && $method_name)
685 || confess "You must pass in a method name";
686 my $method = $fetch_and_prepare_method->($self, $method_name);
687 $method->add_around_modifier(
688 subname(':around' => $method_modifier)
693 # the methods above used to be named like this:
694 # ${pkg}::${method}:(before|after|around)
695 # but this proved problematic when using one modifier
696 # to wrap multiple methods (something which is likely
697 # to happen pretty regularly IMO). So instead of naming
698 # it like this, I have chosen to just name them purely
699 # with their modifier names, like so:
700 # :(before|after|around)
701 # The fact is that in a stack trace, it will be fairly
702 # evident from the context what method they are attached
703 # to, and so don't need the fully qualified name.
707 Carp::cluck("The alias_method method is deprecated. Use add_method instead.\n");
709 shift->add_method(@_);
713 my ($self, $method_name) = @_;
714 (defined $method_name && $method_name)
715 || confess "You must define a method name";
717 exists $self->{methods}{$method_name} || exists $self->get_method_map->{$method_name};
721 my ($self, $method_name) = @_;
722 (defined $method_name && $method_name)
723 || confess "You must define a method name";
725 return $self->{methods}{$method_name} || $self->get_method_map->{$method_name};
729 my ($self, $method_name) = @_;
730 (defined $method_name && $method_name)
731 || confess "You must define a method name";
733 my $removed_method = delete $self->get_method_map->{$method_name};
735 $self->remove_package_symbol(
736 { sigil => '&', type => 'CODE', name => $method_name }
739 $removed_method->detach_from_class if $removed_method;
741 $self->update_package_cache_flag; # still valid, since we just removed the method from the map
743 return $removed_method;
746 sub get_method_list {
748 keys %{$self->get_method_map};
751 sub find_method_by_name {
752 my ($self, $method_name) = @_;
753 (defined $method_name && $method_name)
754 || confess "You must define a method name to find";
755 foreach my $class ($self->linearized_isa) {
756 # fetch the meta-class ...
757 my $meta = $self->initialize($class);
758 return $meta->get_method($method_name)
759 if $meta->has_method($method_name);
764 sub get_all_methods {
766 my %methods = map { %{ $self->initialize($_)->get_method_map } } reverse $self->linearized_isa;
767 return values %methods;
770 sub compute_all_applicable_methods {
771 Carp::cluck('The compute_all_applicable_methods method is deprecated.'
772 . " Use get_all_methods instead.\n");
777 class => $_->package_name,
778 code => $_, # sigh, overloading
780 } shift->get_all_methods(@_);
783 sub get_all_method_names {
786 grep { $uniq{$_}++ == 0 } map { $_->name } $self->get_all_methods;
789 sub find_all_methods_by_name {
790 my ($self, $method_name) = @_;
791 (defined $method_name && $method_name)
792 || confess "You must define a method name to find";
794 foreach my $class ($self->linearized_isa) {
795 # fetch the meta-class ...
796 my $meta = $self->initialize($class);
798 name => $method_name,
800 code => $meta->get_method($method_name)
801 } if $meta->has_method($method_name);
806 sub find_next_method_by_name {
807 my ($self, $method_name) = @_;
808 (defined $method_name && $method_name)
809 || confess "You must define a method name to find";
810 my @cpl = $self->linearized_isa;
811 shift @cpl; # discard ourselves
812 foreach my $class (@cpl) {
813 # fetch the meta-class ...
814 my $meta = $self->initialize($class);
815 return $meta->get_method($method_name)
816 if $meta->has_method($method_name);
825 # either we have an attribute object already
826 # or we need to create one from the args provided
827 my $attribute = blessed($_[0]) ? $_[0] : $self->attribute_metaclass->new(@_);
828 # make sure it is derived from the correct type though
829 ($attribute->isa('Class::MOP::Attribute'))
830 || confess "Your attribute must be an instance of Class::MOP::Attribute (or a subclass)";
832 # first we attach our new attribute
833 # because it might need certain information
834 # about the class which it is attached to
835 $attribute->attach_to_class($self);
837 # then we remove attributes of a conflicting
838 # name here so that we can properly detach
839 # the old attr object, and remove any
840 # accessors it would have generated
841 if ( $self->has_attribute($attribute->name) ) {
842 $self->remove_attribute($attribute->name);
844 $self->invalidate_meta_instances();
847 # get our count of previously inserted attributes and
848 # increment by one so this attribute knows its order
849 my $order = (scalar keys %{$self->get_attribute_map}) - 1;
850 $attribute->_set_insertion_order($order + 1);
852 # then onto installing the new accessors
853 $self->get_attribute_map->{$attribute->name} = $attribute;
855 # invalidate package flag here
856 my $e = do { local $@; eval { $attribute->install_accessors() }; $@ };
858 $self->remove_attribute($attribute->name);
865 sub update_meta_instance_dependencies {
868 if ( $self->{meta_instance_dependencies} ) {
869 return $self->add_meta_instance_dependencies;
873 sub add_meta_instance_dependencies {
876 $self->remove_meta_instance_dependencies;
878 my @attrs = $self->get_all_attributes();
881 my @classes = grep { not $seen{$_->name}++ } map { $_->associated_class } @attrs;
883 foreach my $class ( @classes ) {
884 $class->add_dependent_meta_instance($self);
887 $self->{meta_instance_dependencies} = \@classes;
890 sub remove_meta_instance_dependencies {
893 if ( my $classes = delete $self->{meta_instance_dependencies} ) {
894 foreach my $class ( @$classes ) {
895 $class->remove_dependent_meta_instance($self);
905 sub add_dependent_meta_instance {
906 my ( $self, $metaclass ) = @_;
907 push @{ $self->{dependent_meta_instances} }, $metaclass;
910 sub remove_dependent_meta_instance {
911 my ( $self, $metaclass ) = @_;
912 my $name = $metaclass->name;
913 @$_ = grep { $_->name ne $name } @$_ for $self->{dependent_meta_instances};
916 sub invalidate_meta_instances {
918 $_->invalidate_meta_instance() for $self, @{ $self->{dependent_meta_instances} };
921 sub invalidate_meta_instance {
923 undef $self->{_meta_instance};
927 my ($self, $attribute_name) = @_;
928 (defined $attribute_name && $attribute_name)
929 || confess "You must define an attribute name";
930 exists $self->get_attribute_map->{$attribute_name};
934 my ($self, $attribute_name) = @_;
935 (defined $attribute_name && $attribute_name)
936 || confess "You must define an attribute name";
937 return $self->get_attribute_map->{$attribute_name}
939 # this will return undef anyway, so no need ...
940 # if $self->has_attribute($attribute_name);
944 sub remove_attribute {
945 my ($self, $attribute_name) = @_;
946 (defined $attribute_name && $attribute_name)
947 || confess "You must define an attribute name";
948 my $removed_attribute = $self->get_attribute_map->{$attribute_name};
949 return unless defined $removed_attribute;
950 delete $self->get_attribute_map->{$attribute_name};
951 $self->invalidate_meta_instances();
952 $removed_attribute->remove_accessors();
953 $removed_attribute->detach_from_class();
954 return $removed_attribute;
957 sub get_attribute_list {
959 keys %{$self->get_attribute_map};
962 sub get_all_attributes {
964 my %attrs = map { %{ $self->initialize($_)->get_attribute_map } } reverse $self->linearized_isa;
965 return values %attrs;
968 sub compute_all_applicable_attributes {
969 Carp::cluck('The compute_all_applicable_attributes method has been deprecated.'
970 . " Use get_all_attributes instead.\n");
972 shift->get_all_attributes(@_);
975 sub find_attribute_by_name {
976 my ($self, $attr_name) = @_;
977 foreach my $class ($self->linearized_isa) {
978 # fetch the meta-class ...
979 my $meta = $self->initialize($class);
980 return $meta->get_attribute($attr_name)
981 if $meta->has_attribute($attr_name);
986 # check if we can reinitialize
990 # if any local attr is defined
991 return if $self->get_attribute_list;
993 # or any non-declared methods
994 if ( my @methods = values %{ $self->get_method_map } ) {
995 my $metaclass = $self->method_metaclass;
996 foreach my $method ( @methods ) {
997 return if $method->isa("Class::MOP::Method::Generated");
998 # FIXME do we need to enforce this too? return unless $method->isa($metaclass);
1007 sub is_mutable { 1 }
1008 sub is_immutable { 0 }
1009 sub immutable_transformer { return }
1011 sub _immutable_options {
1012 my ( $self, @args ) = @_;
1015 inline_accessors => 1,
1016 inline_constructor => 1,
1017 inline_destructor => 0,
1019 immutable_trait => $self->immutable_trait,
1020 constructor_name => $self->constructor_name,
1021 constructor_class => $self->constructor_class,
1022 destructor_class => $self->destructor_class,
1027 sub make_immutable {
1028 my ( $self, @args ) = @_;
1030 if ( $self->is_mutable ) {
1031 $self->_initialize_immutable( $self->_immutable_options(@args) );
1032 $self->_rebless_as_immutable(@args);
1043 if ( $self->is_immutable ) {
1044 my @args = $self->immutable_options;
1045 $self->_rebless_as_mutable();
1046 $self->_remove_inlined_code(@args);
1047 delete $self->{__immutable};
1055 sub _rebless_as_immutable {
1056 my ( $self, @args ) = @_;
1058 $self->{__immutable}{original_class} = ref $self;
1060 bless $self => $self->_immutable_metaclass(@args);
1063 sub _immutable_metaclass {
1064 my ( $self, %args ) = @_;
1066 if ( my $class = $args{immutable_metaclass} ) {
1070 my $trait = $args{immutable_trait} = $self->immutable_trait
1071 || confess "no immutable trait specified for $self";
1073 my $meta_attr = $self->meta->find_attribute_by_name("immutable_trait");
1077 if ( $meta_attr and $trait eq $meta_attr->default ) {
1079 # if the trait is the same as the default we try and pick a predictable
1080 # name for the immutable metaclass
1081 $class_name = "Class::MOP::Class::Immutable::" . ref($self);
1085 = join( "::", "Class::MOP::Class::Immutable::CustomTrait", $trait,
1086 "ForMetaClass", ref($self) );
1089 if ( Class::MOP::is_class_loaded($class_name) ) {
1090 if ( $class_name->isa($trait) ) {
1095 "$class_name is already defined but does not inherit $trait";
1099 my @super = ( $trait, ref($self) );
1101 my $meta = Class::MOP::Class->initialize($class_name);
1102 $meta->superclasses(@super);
1104 $meta->make_immutable;
1110 sub _remove_inlined_code {
1113 $self->remove_method( $_->name ) for $self->_inlined_methods;
1115 delete $self->{__immutable}{inlined_methods};
1118 sub _inlined_methods { @{ $_[0]{__immutable}{inlined_methods} || [] } }
1120 sub _add_inlined_method {
1121 my ( $self, $method ) = @_;
1123 push @{ $self->{__immutable}{inlined_methods} ||= [] }, $method;
1126 sub _initialize_immutable {
1127 my ( $self, %args ) = @_;
1129 $self->{__immutable}{options} = \%args;
1130 $self->_install_inlined_code(%args);
1133 sub _install_inlined_code {
1134 my ( $self, %args ) = @_;
1137 $self->_inline_accessors(%args) if $args{inline_accessors};
1138 $self->_inline_constructor(%args) if $args{inline_constructor};
1139 $self->_inline_destructor(%args) if $args{inline_destructor};
1142 sub _rebless_as_mutable {
1145 bless $self, $self->get_mutable_metaclass_name;
1150 sub _inline_accessors {
1153 foreach my $attr_name ( $self->get_attribute_list ) {
1154 $self->get_attribute($attr_name)->install_accessors(1);
1158 sub _inline_constructor {
1159 my ( $self, %args ) = @_;
1161 my $name = $args{constructor_name};
1163 #if ( my $existing = $self->name->can($args{constructor_name}) ) {
1164 # if ( refaddr($existing) == refaddr(\&Moose::Object::new) ) {
1166 unless ( $args{replace_constructor}
1167 or !$self->has_method($name) ) {
1168 my $class = $self->name;
1169 warn "Not inlining a constructor for $class since it defines"
1170 . " its own constructor.\n"
1171 . "If you are certain you don't need to inline your"
1172 . " constructor, specify inline_constructor => 0 in your"
1173 . " call to $class->meta->make_immutable\n";
1177 my $constructor_class = $args{constructor_class};
1179 Class::MOP::load_class($constructor_class);
1181 my $constructor = $constructor_class->new(
1185 package_name => $self->name,
1189 if ( $args{replace_constructor} or $constructor->can_be_inlined ) {
1190 $self->add_method( $name => $constructor );
1191 $self->_add_inlined_method($constructor);
1195 sub _inline_destructor {
1196 my ( $self, %args ) = @_;
1198 ( exists $args{destructor_class} )
1199 || confess "The 'inline_destructor' option is present, but "
1200 . "no destructor class was specified";
1202 my $destructor_class = $args{destructor_class};
1204 Class::MOP::load_class($destructor_class);
1206 return unless $destructor_class->is_needed($self);
1208 my $destructor = $destructor_class->new(
1211 package_name => $self->name,
1215 $self->add_method( 'DESTROY' => $destructor );
1217 $self->_add_inlined_method($destructor);
1228 Class::MOP::Class - Class Meta Object
1232 # assuming that class Foo
1233 # has been defined, you can
1235 # use this for introspection ...
1237 # add a method to Foo ...
1238 Foo->meta->add_method( 'bar' => sub {...} )
1240 # get a list of all the classes searched
1241 # the method dispatcher in the correct order
1242 Foo->meta->class_precedence_list()
1244 # remove a method from Foo
1245 Foo->meta->remove_method('bar');
1247 # or use this to actually create classes ...
1249 Class::MOP::Class->create(
1252 superclasses => ['Foo'],
1254 Class::MOP::Attribute->new('$bar'),
1255 Class::MOP::Attribute->new('$baz'),
1258 calculate_bar => sub {...},
1259 construct_baz => sub {...}
1266 The Class Protocol is the largest and most complex part of the
1267 Class::MOP meta-object protocol. It controls the introspection and
1268 manipulation of Perl 5 classes, and it can create them as well. The
1269 best way to understand what this module can do, is to read the
1270 documentation for each of its methods.
1274 C<Class::MOP::Class> is a subclass of L<Class::MOP::Module>.
1278 =head2 Class construction
1280 These methods all create new C<Class::MOP::Class> objects. These
1281 objects can represent existing classes, or they can be used to create
1282 new classes from scratch.
1284 The metaclass object for a given class is a singleton. If you attempt
1285 to create a metaclass for the same class twice, you will just get the
1290 =item B<< Class::MOP::Class->create($package_name, %options) >>
1292 This method creates a new C<Class::MOP::Class> object with the given
1293 package name. It accepts a number of options.
1299 An optional version number for the newly created package.
1303 An optional authority for the newly created package.
1305 =item * superclasses
1307 An optional array reference of superclass names.
1311 An optional hash reference of methods for the class. The keys of the
1312 hash reference are method names, and values are subroutine references.
1316 An optional array reference of attributes.
1318 An attribute can be passed as an existing L<Class::MOP::Attribute>
1319 object, I<or> or as a hash reference of options which will be passed
1320 to the attribute metaclass's constructor.
1324 =item B<< Class::MOP::Class->create_anon_class(%options) >>
1326 This method works just like C<< Class::MOP::Class->create >> but it
1327 creates an "anonymous" class. In fact, the class does have a name, but
1328 that name is a unique name generated internally by this module.
1330 It accepts the same C<superclasses>, C<methods>, and C<attributes>
1331 parameters that C<create> accepts.
1333 Anonymous classes are destroyed once the metaclass they are attached
1334 to goes out of scope, and will be removed from Perl's internal symbol
1337 All instances of an anonymous class keep a special reference to the
1338 metaclass object, which prevents the metaclass from going out of scope
1339 while any instances exist.
1341 This only works if the instance if based on a hash reference, however.
1343 =item B<< Class::MOP::Class->initialize($package_name, %options) >>
1345 This method will initialize a C<Class::MOP::Class> object for the
1346 named package. Unlike C<create>, this method I<will not> create a new
1349 The purpose of this method is to retrieve a C<Class::MOP::Class>
1350 object for introspecting an existing class.
1352 If an existing C<Class::MOP::Class> object exists for the named
1353 package, it will be returned, and any options provided will be
1356 If the object does not yet exist, it will be created.
1358 The valid options that can be passed to this method are
1359 C<attribute_metaclass>, C<method_metaclass>,
1360 C<wrapped_method_metaclass>, and C<instance_metaclass>. These are all
1361 optional, and default to the appropriate class in the C<Class::MOP>
1366 =head2 Object instance construction and cloning
1368 These methods are all related to creating and/or cloning object
1373 =item B<< $metaclass->clone_object($instance, %params) >>
1375 This method clones an existing object instance. Any parameters you
1376 provide are will override existing attribute values in the object.
1378 This is a convenience method for cloning an object instance, then
1379 blessing it into the appropriate package.
1381 You could implement a clone method in your class, using this method:
1384 my ($self, %params) = @_;
1385 $self->meta->clone_object($self, %params);
1388 =item B<< $metaclass->rebless_instance($instance, %params) >>
1390 This method changes the class of C<$instance> to the metaclass's class.
1392 You can only rebless an instance into a subclass of its current
1393 class. If you pass any additional parameters, these will be treated
1394 like constructor parameters and used to initialize the object's
1395 attributes. Any existing attributes that are already set will be
1398 Before reblessing the instance, this method will call
1399 C<rebless_instance_away> on the instance's current metaclass. This method
1400 will be passed the instance, the new metaclass, and any parameters
1401 specified to C<rebless_instance>. By default, C<rebless_instance_away>
1402 does nothing; it is merely a hook.
1404 =item B<< $metaclass->new_object(%params) >>
1406 This method is used to create a new object of the metaclass's
1407 class. Any parameters you provide are used to initialize the
1408 instance's attributes.
1410 =item B<< $metaclass->instance_metaclass >>
1412 Returns the class name of the instance metaclass, see
1413 L<Class::MOP::Instance> for more information on the instance
1416 =item B<< $metaclass->get_meta_instance >>
1418 Returns an instance of the C<instance_metaclass> to be used in the
1419 construction of a new instance of the class.
1423 =head2 Informational predicates
1425 These are a few predicate methods for asking information about the
1430 =item B<< $metaclass->is_anon_class >>
1432 This returns true if the class was created by calling C<<
1433 Class::MOP::Class->create_anon_class >>.
1435 =item B<< $metaclass->is_mutable >>
1437 This returns true if the class is still mutable.
1439 =item B<< $metaclass->is_immutable >>
1441 This returns true if the class has been made immutable.
1443 =item B<< $metaclass->is_pristine >>
1445 A class is I<not> pristine if it has non-inherited attributes or if it
1446 has any generated methods.
1450 =head2 Inheritance Relationships
1454 =item B<< $metaclass->superclasses(@superclasses) >>
1456 This is a read-write accessor which represents the superclass
1457 relationships of the metaclass's class.
1459 This is basically sugar around getting and setting C<@ISA>.
1461 =item B<< $metaclass->class_precedence_list >>
1463 This returns a list of all of the class's ancestor classes. The
1464 classes are returned in method dispatch order.
1466 =item B<< $metaclass->linearized_isa >>
1468 This returns a list based on C<class_precedence_list> but with all
1471 =item B<< $metaclass->subclasses >>
1473 This returns a list of all subclasses for this class, even indirect
1476 =item B<< $metaclass->direct_subclasses >>
1478 This returns a list of immediate subclasses for this class, which does not
1479 include indirect subclasses.
1483 =head2 Method introspection and creation
1485 These methods allow you to introspect a class's methods, as well as
1486 add, remove, or change methods.
1488 Determining what is truly a method in a Perl 5 class requires some
1489 heuristics (aka guessing).
1491 Methods defined outside the package with a fully qualified name (C<sub
1492 Package::name { ... }>) will be included. Similarly, methods named
1493 with a fully qualified name using L<Sub::Name> are also included.
1495 However, we attempt to ignore imported functions.
1497 Ultimately, we are using heuristics to determine what truly is a
1498 method in a class, and these heuristics may get the wrong answer in
1499 some edge cases. However, for most "normal" cases the heuristics work
1504 =item B<< $metaclass->get_method($method_name) >>
1506 This will return a L<Class::MOP::Method> for the specified
1507 C<$method_name>. If the class does not have the specified method, it
1510 =item B<< $metaclass->has_method($method_name) >>
1512 Returns a boolean indicating whether or not the class defines the
1513 named method. It does not include methods inherited from parent
1516 =item B<< $metaclass->get_method_map >>
1518 Returns a hash reference representing the methods defined in this
1519 class. The keys are method names and the values are
1520 L<Class::MOP::Method> objects.
1522 =item B<< $metaclass->get_method_list >>
1524 This will return a list of method I<names> for all methods defined in
1527 =item B<< $metaclass->get_all_methods >>
1529 This will traverse the inheritance hierarchy and return a list of all
1530 the L<Class::MOP::Method> objects for this class and its parents.
1532 =item B<< $metaclass->find_method_by_name($method_name) >>
1534 This will return a L<Class::MOP::Method> for the specified
1535 C<$method_name>. If the class does not have the specified method, it
1538 Unlike C<get_method>, this method I<will> look for the named method in
1541 =item B<< $metaclass->get_all_method_names >>
1543 This will return a list of method I<names> for all of this class's
1544 methods, including inherited methods.
1546 =item B<< $metaclass->find_all_methods_by_name($method_name) >>
1548 This method looks for the named method in the class and all of its
1549 parents. It returns every matching method it finds in the inheritance
1550 tree, so it returns a list of methods.
1552 Each method is returned as a hash reference with three keys. The keys
1553 are C<name>, C<class>, and C<code>. The C<code> key has a
1554 L<Class::MOP::Method> object as its value.
1556 The list of methods is distinct.
1558 =item B<< $metaclass->find_next_method_by_name($method_name) >>
1560 This method returns the first method in any superclass matching the
1561 given name. It is effectively the method that C<SUPER::$method_name>
1564 =item B<< $metaclass->add_method($method_name, $method) >>
1566 This method takes a method name and a subroutine reference, and adds
1567 the method to the class.
1569 The subroutine reference can be a L<Class::MOP::Method>, and you are
1570 strongly encouraged to pass a meta method object instead of a code
1571 reference. If you do so, that object gets stored as part of the
1572 class's method map directly. If not, the meta information will have to
1573 be recreated later, and may be incorrect.
1575 If you provide a method object, this method will clone that object if
1576 the object's package name does not match the class name. This lets us
1577 track the original source of any methods added from other classes
1578 (notably Moose roles).
1580 =item B<< $metaclass->remove_method($method_name) >>
1582 Remove the named method from the class. This method returns the
1583 L<Class::MOP::Method> object for the method.
1585 =item B<< $metaclass->method_metaclass >>
1587 Returns the class name of the method metaclass, see
1588 L<Class::MOP::Method> for more information on the method metaclass.
1590 =item B<< $metaclass->wrapped_method_metaclass >>
1592 Returns the class name of the wrapped method metaclass, see
1593 L<Class::MOP::Method::Wrapped> for more information on the wrapped
1598 =head2 Attribute introspection and creation
1600 Because Perl 5 does not have a core concept of attributes in classes,
1601 we can only return information about attributes which have been added
1602 via this class's methods. We cannot discover information about
1603 attributes which are defined in terms of "regular" Perl 5 methods.
1607 =item B<< $metaclass->get_attribute($attribute_name) >>
1609 This will return a L<Class::MOP::Attribute> for the specified
1610 C<$attribute_name>. If the class does not have the specified
1611 attribute, it returns C<undef>
1613 =item B<< $metaclass->has_attribute($attribute_name) >>
1615 Returns a boolean indicating whether or not the class defines the
1616 named attribute. It does not include attributes inherited from parent
1619 =item B<< $metaclass->get_attribute_map >>
1621 Returns a hash reference representing the attributes defined in this
1622 class. The keys are attribute names and the values are
1623 L<Class::MOP::Attribute> objects.
1625 =item B<< $metaclass->get_attribute_list >>
1627 This will return a list of attributes I<names> for all attributes
1628 defined in this class.
1630 =item B<< $metaclass->get_all_attributes >>
1632 This will traverse the inheritance hierarchy and return a list of all
1633 the L<Class::MOP::Attribute> objects for this class and its parents.
1635 =item B<< $metaclass->find_attribute_by_name($attribute_name) >>
1637 This will return a L<Class::MOP::Attribute> for the specified
1638 C<$attribute_name>. If the class does not have the specified
1639 attribute, it returns C<undef>
1641 Unlike C<get_attribute>, this attribute I<will> look for the named
1642 attribute in superclasses.
1644 =item B<< $metaclass->add_attribute(...) >>
1646 This method accepts either an existing L<Class::MOP::Attribute>
1647 object, or parameters suitable for passing to that class's C<new>
1650 The attribute provided will be added to the class.
1652 Any accessor methods defined by the attribute will be added to the
1653 class when the attribute is added.
1655 If an attribute of the same name already exists, the old attribute
1656 will be removed first.
1658 =item B<< $metaclass->remove_attribute($attribute_name) >>
1660 This will remove the named attribute from the class, and
1661 L<Class::MOP::Attribute> object.
1663 Removing an attribute also removes any accessor methods defined by the
1666 However, note that removing an attribute will only affect I<future>
1667 object instances created for this class, not existing instances.
1669 =item B<< $metaclass->attribute_metaclass >>
1671 Returns the class name of the attribute metaclass for this class. By
1672 default, this is L<Class::MOP::Attribute>. for more information on
1676 =head2 Class Immutability
1678 Making a class immutable "freezes" the class definition. You can no
1679 longer call methods which alter the class, such as adding or removing
1680 methods or attributes.
1682 Making a class immutable lets us optimize the class by inlining some
1683 methods, and also allows us to optimize some methods on the metaclass
1686 The immutabilization system in L<Moose> takes much greater advantage
1687 of the inlining features than Class::MOP itself does.
1691 =item B<< $metaclass->make_immutable(%options) >>
1693 This method will create an immutable transformer and uses it to make
1694 the class and its metaclass object immutable.
1696 Details of how immutabilization works are in L<Class::MOP::Immutable>
1699 =item B<< $metaclass->make_mutable >>
1701 Calling this method reverse the immutabilization transformation.
1703 =item B<< $metaclass->immutable_transformer >>
1705 If the class has been made immutable previously, this returns the
1706 L<Class::MOP::Immutable> object that was created to do the
1709 If the class was never made immutable, this method will die.
1713 =head2 Method Modifiers
1715 Method modifiers are hooks which allow a method to be wrapped with
1716 I<before>, I<after> and I<around> method modifiers. Every time a
1717 method is called, it's modifiers are also called.
1719 A class can modify its own methods, as well as methods defined in
1722 =head3 How method modifiers work?
1724 Method modifiers work by wrapping the original method and then
1725 replacing it in the class's symbol table. The wrappers will handle
1726 calling all the modifiers in the appropriate order and preserving the
1727 calling context for the original method.
1729 The return values of C<before> and C<after> modifiers are
1730 ignored. This is because their purpose is B<not> to filter the input
1731 and output of the primary method (this is done with an I<around>
1734 This may seem like an odd restriction to some, but doing this allows
1735 for simple code to be added at the beginning or end of a method call
1736 without altering the function of the wrapped method or placing any
1737 extra responsibility on the code of the modifier.
1739 Of course if you have more complex needs, you can use the C<around>
1740 modifier which allows you to change both the parameters passed to the
1741 wrapped method, as well as its return value.
1743 Before and around modifiers are called in last-defined-first-called
1744 order, while after modifiers are called in first-defined-first-called
1745 order. So the call tree might looks something like this:
1757 =head3 What is the performance impact?
1759 Of course there is a performance cost associated with method
1760 modifiers, but we have made every effort to make that cost directly
1761 proportional to the number of modifier features you utilize.
1763 The wrapping method does it's best to B<only> do as much work as it
1764 absolutely needs to. In order to do this we have moved some of the
1765 performance costs to set-up time, where they are easier to amortize.
1767 All this said, our benchmarks have indicated the following:
1769 simple wrapper with no modifiers 100% slower
1770 simple wrapper with simple before modifier 400% slower
1771 simple wrapper with simple after modifier 450% slower
1772 simple wrapper with simple around modifier 500-550% slower
1773 simple wrapper with all 3 modifiers 1100% slower
1775 These numbers may seem daunting, but you must remember, every feature
1776 comes with some cost. To put things in perspective, just doing a
1777 simple C<AUTOLOAD> which does nothing but extract the name of the
1778 method called and return it costs about 400% over a normal method
1783 =item B<< $metaclass->add_before_method_modifier($method_name, $code) >>
1785 This wraps the specified method with the supplied subroutine
1786 reference. The modifier will be called as a method itself, and will
1787 receive the same arguments as are passed to the method.
1789 When the modifier exits, the wrapped method will be called.
1791 The return value of the modifier will be ignored.
1793 =item B<< $metaclass->add_after_method_modifier($method_name, $code) >>
1795 This wraps the specified method with the supplied subroutine
1796 reference. The modifier will be called as a method itself, and will
1797 receive the same arguments as are passed to the method.
1799 When the wrapped methods exits, the modifier will be called.
1801 The return value of the modifier will be ignored.
1803 =item B<< $metaclass->add_around_method_modifier($method_name, $code) >>
1805 This wraps the specified method with the supplied subroutine
1808 The first argument passed to the modifier will be a subroutine
1809 reference to the wrapped method. The second argument is the object,
1810 and after that come any arguments passed when the method is called.
1812 The around modifier can choose to call the original method, as well as
1813 what arguments to pass if it does so.
1815 The return value of the modifier is what will be seen by the caller.
1819 =head2 Introspection
1823 =item B<< Class::MOP::Class->meta >>
1825 This will return a L<Class::MOP::Class> instance for this class.
1827 It should also be noted that L<Class::MOP> will actually bootstrap
1828 this module by installing a number of attribute meta-objects into its
1835 Stevan Little E<lt>stevan@iinteractive.comE<gt>
1837 =head1 COPYRIGHT AND LICENSE
1839 Copyright 2006-2009 by Infinity Interactive, Inc.
1841 L<http://www.iinteractive.com>
1843 This library is free software; you can redistribute it and/or modify
1844 it under the same terms as Perl itself.