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 $full_method_name = ($self->name . '::' . $method_name);
623 $self->add_package_symbol(
624 { sigil => '&', type => 'CODE', name => $method_name },
625 subname($full_method_name => $body)
630 my $fetch_and_prepare_method = sub {
631 my ($self, $method_name) = @_;
632 my $wrapped_metaclass = $self->wrapped_method_metaclass;
634 my $method = $self->get_method($method_name);
635 # if we dont have local ...
637 # try to find the next method
638 $method = $self->find_next_method_by_name($method_name);
639 # die if it does not exist
641 || confess "The method '$method_name' was not found in the inheritance hierarchy for " . $self->name;
642 # and now make sure to wrap it
643 # even if it is already wrapped
644 # because we need a new sub ref
645 $method = $wrapped_metaclass->wrap($method);
648 # now make sure we wrap it properly
649 $method = $wrapped_metaclass->wrap($method)
650 unless $method->isa($wrapped_metaclass);
652 $self->add_method($method_name => $method);
656 sub add_before_method_modifier {
657 my ($self, $method_name, $method_modifier) = @_;
658 (defined $method_name && $method_name)
659 || confess "You must pass in a method name";
660 my $method = $fetch_and_prepare_method->($self, $method_name);
661 $method->add_before_modifier(
662 subname(':before' => $method_modifier)
666 sub add_after_method_modifier {
667 my ($self, $method_name, $method_modifier) = @_;
668 (defined $method_name && $method_name)
669 || confess "You must pass in a method name";
670 my $method = $fetch_and_prepare_method->($self, $method_name);
671 $method->add_after_modifier(
672 subname(':after' => $method_modifier)
676 sub add_around_method_modifier {
677 my ($self, $method_name, $method_modifier) = @_;
678 (defined $method_name && $method_name)
679 || confess "You must pass in a method name";
680 my $method = $fetch_and_prepare_method->($self, $method_name);
681 $method->add_around_modifier(
682 subname(':around' => $method_modifier)
687 # the methods above used to be named like this:
688 # ${pkg}::${method}:(before|after|around)
689 # but this proved problematic when using one modifier
690 # to wrap multiple methods (something which is likely
691 # to happen pretty regularly IMO). So instead of naming
692 # it like this, I have chosen to just name them purely
693 # with their modifier names, like so:
694 # :(before|after|around)
695 # The fact is that in a stack trace, it will be fairly
696 # evident from the context what method they are attached
697 # to, and so don't need the fully qualified name.
701 Carp::cluck("The alias_method method is deprecated. Use add_method instead.\n");
703 shift->add_method(@_);
707 my ($self, $method_name) = @_;
708 (defined $method_name && $method_name)
709 || confess "You must define a method name";
711 exists $self->{methods}{$method_name} || exists $self->get_method_map->{$method_name};
715 my ($self, $method_name) = @_;
716 (defined $method_name && $method_name)
717 || confess "You must define a method name";
719 return $self->{methods}{$method_name} || $self->get_method_map->{$method_name};
723 my ($self, $method_name) = @_;
724 (defined $method_name && $method_name)
725 || confess "You must define a method name";
727 my $removed_method = delete $self->get_method_map->{$method_name};
729 $self->remove_package_symbol(
730 { sigil => '&', type => 'CODE', name => $method_name }
733 $removed_method->detach_from_class if $removed_method;
735 $self->update_package_cache_flag; # still valid, since we just removed the method from the map
737 return $removed_method;
740 sub get_method_list {
742 keys %{$self->get_method_map};
745 sub find_method_by_name {
746 my ($self, $method_name) = @_;
747 (defined $method_name && $method_name)
748 || confess "You must define a method name to find";
749 foreach my $class ($self->linearized_isa) {
750 # fetch the meta-class ...
751 my $meta = $self->initialize($class);
752 return $meta->get_method($method_name)
753 if $meta->has_method($method_name);
758 sub get_all_methods {
760 my %methods = map { %{ $self->initialize($_)->get_method_map } } reverse $self->linearized_isa;
761 return values %methods;
764 sub compute_all_applicable_methods {
765 Carp::cluck('The compute_all_applicable_methods method is deprecated.'
766 . " Use get_all_methods instead.\n");
771 class => $_->package_name,
772 code => $_, # sigh, overloading
774 } shift->get_all_methods(@_);
777 sub get_all_method_names {
780 grep { $uniq{$_}++ == 0 } map { $_->name } $self->get_all_methods;
783 sub find_all_methods_by_name {
784 my ($self, $method_name) = @_;
785 (defined $method_name && $method_name)
786 || confess "You must define a method name to find";
788 foreach my $class ($self->linearized_isa) {
789 # fetch the meta-class ...
790 my $meta = $self->initialize($class);
792 name => $method_name,
794 code => $meta->get_method($method_name)
795 } if $meta->has_method($method_name);
800 sub find_next_method_by_name {
801 my ($self, $method_name) = @_;
802 (defined $method_name && $method_name)
803 || confess "You must define a method name to find";
804 my @cpl = $self->linearized_isa;
805 shift @cpl; # discard ourselves
806 foreach my $class (@cpl) {
807 # fetch the meta-class ...
808 my $meta = $self->initialize($class);
809 return $meta->get_method($method_name)
810 if $meta->has_method($method_name);
819 # either we have an attribute object already
820 # or we need to create one from the args provided
821 my $attribute = blessed($_[0]) ? $_[0] : $self->attribute_metaclass->new(@_);
822 # make sure it is derived from the correct type though
823 ($attribute->isa('Class::MOP::Attribute'))
824 || confess "Your attribute must be an instance of Class::MOP::Attribute (or a subclass)";
826 # first we attach our new attribute
827 # because it might need certain information
828 # about the class which it is attached to
829 $attribute->attach_to_class($self);
831 # then we remove attributes of a conflicting
832 # name here so that we can properly detach
833 # the old attr object, and remove any
834 # accessors it would have generated
835 if ( $self->has_attribute($attribute->name) ) {
836 $self->remove_attribute($attribute->name);
838 $self->invalidate_meta_instances();
841 # get our count of previously inserted attributes and
842 # increment by one so this attribute knows its order
843 my $order = (scalar keys %{$self->get_attribute_map}) - 1;
844 $attribute->_set_insertion_order($order + 1);
846 # then onto installing the new accessors
847 $self->get_attribute_map->{$attribute->name} = $attribute;
849 # invalidate package flag here
850 my $e = do { local $@; eval { $attribute->install_accessors() }; $@ };
852 $self->remove_attribute($attribute->name);
859 sub update_meta_instance_dependencies {
862 if ( $self->{meta_instance_dependencies} ) {
863 return $self->add_meta_instance_dependencies;
867 sub add_meta_instance_dependencies {
870 $self->remove_meta_instance_dependencies;
872 my @attrs = $self->get_all_attributes();
875 my @classes = grep { not $seen{$_->name}++ } map { $_->associated_class } @attrs;
877 foreach my $class ( @classes ) {
878 $class->add_dependent_meta_instance($self);
881 $self->{meta_instance_dependencies} = \@classes;
884 sub remove_meta_instance_dependencies {
887 if ( my $classes = delete $self->{meta_instance_dependencies} ) {
888 foreach my $class ( @$classes ) {
889 $class->remove_dependent_meta_instance($self);
899 sub add_dependent_meta_instance {
900 my ( $self, $metaclass ) = @_;
901 push @{ $self->{dependent_meta_instances} }, $metaclass;
904 sub remove_dependent_meta_instance {
905 my ( $self, $metaclass ) = @_;
906 my $name = $metaclass->name;
907 @$_ = grep { $_->name ne $name } @$_ for $self->{dependent_meta_instances};
910 sub invalidate_meta_instances {
912 $_->invalidate_meta_instance() for $self, @{ $self->{dependent_meta_instances} };
915 sub invalidate_meta_instance {
917 undef $self->{_meta_instance};
921 my ($self, $attribute_name) = @_;
922 (defined $attribute_name && $attribute_name)
923 || confess "You must define an attribute name";
924 exists $self->get_attribute_map->{$attribute_name};
928 my ($self, $attribute_name) = @_;
929 (defined $attribute_name && $attribute_name)
930 || confess "You must define an attribute name";
931 return $self->get_attribute_map->{$attribute_name}
933 # this will return undef anyway, so no need ...
934 # if $self->has_attribute($attribute_name);
938 sub remove_attribute {
939 my ($self, $attribute_name) = @_;
940 (defined $attribute_name && $attribute_name)
941 || confess "You must define an attribute name";
942 my $removed_attribute = $self->get_attribute_map->{$attribute_name};
943 return unless defined $removed_attribute;
944 delete $self->get_attribute_map->{$attribute_name};
945 $self->invalidate_meta_instances();
946 $removed_attribute->remove_accessors();
947 $removed_attribute->detach_from_class();
948 return $removed_attribute;
951 sub get_attribute_list {
953 keys %{$self->get_attribute_map};
956 sub get_all_attributes {
958 my %attrs = map { %{ $self->initialize($_)->get_attribute_map } } reverse $self->linearized_isa;
959 return values %attrs;
962 sub compute_all_applicable_attributes {
963 Carp::cluck('The compute_all_applicable_attributes method has been deprecated.'
964 . " Use get_all_attributes instead.\n");
966 shift->get_all_attributes(@_);
969 sub find_attribute_by_name {
970 my ($self, $attr_name) = @_;
971 foreach my $class ($self->linearized_isa) {
972 # fetch the meta-class ...
973 my $meta = $self->initialize($class);
974 return $meta->get_attribute($attr_name)
975 if $meta->has_attribute($attr_name);
980 # check if we can reinitialize
984 # if any local attr is defined
985 return if $self->get_attribute_list;
987 # or any non-declared methods
988 if ( my @methods = values %{ $self->get_method_map } ) {
989 my $metaclass = $self->method_metaclass;
990 foreach my $method ( @methods ) {
991 return if $method->isa("Class::MOP::Method::Generated");
992 # FIXME do we need to enforce this too? return unless $method->isa($metaclass);
1001 sub is_mutable { 1 }
1002 sub is_immutable { 0 }
1003 sub immutable_transformer { return }
1005 sub _immutable_options {
1006 my ( $self, @args ) = @_;
1009 inline_accessors => 1,
1010 inline_constructor => 1,
1011 inline_destructor => 0,
1013 immutable_trait => $self->immutable_trait,
1014 constructor_name => $self->constructor_name,
1015 constructor_class => $self->constructor_class,
1016 destructor_class => $self->destructor_class,
1021 sub make_immutable {
1022 my ( $self, @args ) = @_;
1024 if ( $self->is_mutable ) {
1025 $self->_initialize_immutable( $self->_immutable_options(@args) );
1026 $self->_rebless_as_immutable(@args);
1037 if ( $self->is_immutable ) {
1038 my @args = $self->immutable_options;
1039 $self->_rebless_as_mutable();
1040 $self->_remove_inlined_code(@args);
1041 delete $self->{__immutable};
1049 sub _rebless_as_immutable {
1050 my ( $self, @args ) = @_;
1052 $self->{__immutable}{original_class} = ref $self;
1054 bless $self => $self->_immutable_metaclass(@args);
1057 sub _immutable_metaclass {
1058 my ( $self, %args ) = @_;
1060 if ( my $class = $args{immutable_metaclass} ) {
1064 my $trait = $args{immutable_trait} = $self->immutable_trait
1065 || confess "no immutable trait specified for $self";
1067 my $meta_attr = $self->meta->find_attribute_by_name("immutable_trait");
1071 if ( $meta_attr and $trait eq $meta_attr->default ) {
1073 # if the trait is the same as the default we try and pick a predictable
1074 # name for the immutable metaclass
1075 $class_name = "Class::MOP::Class::Immutable::" . ref($self);
1079 = join( "::", "Class::MOP::Class::Immutable::CustomTrait", $trait,
1080 "ForMetaClass", ref($self) );
1083 if ( Class::MOP::is_class_loaded($class_name) ) {
1084 if ( $class_name->isa($trait) ) {
1089 "$class_name is already defined but does not inherit $trait";
1093 my @super = ( $trait, ref($self) );
1095 my $meta = Class::MOP::Class->initialize($class_name);
1096 $meta->superclasses(@super);
1098 $meta->make_immutable;
1104 sub _remove_inlined_code {
1107 $self->remove_method( $_->name ) for $self->_inlined_methods;
1109 delete $self->{__immutable}{inlined_methods};
1112 sub _inlined_methods { @{ $_[0]{__immutable}{inlined_methods} || [] } }
1114 sub _add_inlined_method {
1115 my ( $self, $method ) = @_;
1117 push @{ $self->{__immutable}{inlined_methods} ||= [] }, $method;
1120 sub _initialize_immutable {
1121 my ( $self, %args ) = @_;
1123 $self->{__immutable}{options} = \%args;
1124 $self->_install_inlined_code(%args);
1127 sub _install_inlined_code {
1128 my ( $self, %args ) = @_;
1131 $self->_inline_accessors(%args) if $args{inline_accessors};
1132 $self->_inline_constructor(%args) if $args{inline_constructor};
1133 $self->_inline_destructor(%args) if $args{inline_destructor};
1136 sub _rebless_as_mutable {
1139 bless $self, $self->get_mutable_metaclass_name;
1144 sub _inline_accessors {
1147 foreach my $attr_name ( $self->get_attribute_list ) {
1148 $self->get_attribute($attr_name)->install_accessors(1);
1152 sub _inline_constructor {
1153 my ( $self, %args ) = @_;
1155 my $name = $args{constructor_name};
1157 #if ( my $existing = $self->name->can($args{constructor_name}) ) {
1158 # if ( refaddr($existing) == refaddr(\&Moose::Object::new) ) {
1160 unless ( $args{replace_constructor}
1161 or !$self->has_method($name) ) {
1162 my $class = $self->name;
1163 warn "Not inlining a constructor for $class since it defines"
1164 . " its own constructor.\n"
1165 . "If you are certain you don't need to inline your"
1166 . " constructor, specify inline_constructor => 0 in your"
1167 . " call to $class->meta->make_immutable\n";
1171 my $constructor_class = $args{constructor_class};
1173 Class::MOP::load_class($constructor_class);
1175 my $constructor = $constructor_class->new(
1179 package_name => $self->name,
1183 if ( $args{replace_constructor} or $constructor->can_be_inlined ) {
1184 $self->add_method( $name => $constructor );
1185 $self->_add_inlined_method($constructor);
1189 sub _inline_destructor {
1190 my ( $self, %args ) = @_;
1192 ( exists $args{destructor_class} )
1193 || confess "The 'inline_destructor' option is present, but "
1194 . "no destructor class was specified";
1196 my $destructor_class = $args{destructor_class};
1198 Class::MOP::load_class($destructor_class);
1200 return unless $destructor_class->is_needed($self);
1202 my $destructor = $destructor_class->new(
1205 package_name => $self->name,
1209 $self->add_method( 'DESTROY' => $destructor );
1211 $self->_add_inlined_method($destructor);
1222 Class::MOP::Class - Class Meta Object
1226 # assuming that class Foo
1227 # has been defined, you can
1229 # use this for introspection ...
1231 # add a method to Foo ...
1232 Foo->meta->add_method( 'bar' => sub {...} )
1234 # get a list of all the classes searched
1235 # the method dispatcher in the correct order
1236 Foo->meta->class_precedence_list()
1238 # remove a method from Foo
1239 Foo->meta->remove_method('bar');
1241 # or use this to actually create classes ...
1243 Class::MOP::Class->create(
1246 superclasses => ['Foo'],
1248 Class::MOP::Attribute->new('$bar'),
1249 Class::MOP::Attribute->new('$baz'),
1252 calculate_bar => sub {...},
1253 construct_baz => sub {...}
1260 The Class Protocol is the largest and most complex part of the
1261 Class::MOP meta-object protocol. It controls the introspection and
1262 manipulation of Perl 5 classes, and it can create them as well. The
1263 best way to understand what this module can do, is to read the
1264 documentation for each of its methods.
1268 C<Class::MOP::Class> is a subclass of L<Class::MOP::Module>.
1272 =head2 Class construction
1274 These methods all create new C<Class::MOP::Class> objects. These
1275 objects can represent existing classes, or they can be used to create
1276 new classes from scratch.
1278 The metaclass object for a given class is a singleton. If you attempt
1279 to create a metaclass for the same class twice, you will just get the
1284 =item B<< Class::MOP::Class->create($package_name, %options) >>
1286 This method creates a new C<Class::MOP::Class> object with the given
1287 package name. It accepts a number of options.
1293 An optional version number for the newly created package.
1297 An optional authority for the newly created package.
1299 =item * superclasses
1301 An optional array reference of superclass names.
1305 An optional hash reference of methods for the class. The keys of the
1306 hash reference are method names, and values are subroutine references.
1310 An optional array reference of attributes.
1312 An attribute can be passed as an existing L<Class::MOP::Attribute>
1313 object, I<or> or as a hash reference of options which will be passed
1314 to the attribute metaclass's constructor.
1318 =item B<< Class::MOP::Class->create_anon_class(%options) >>
1320 This method works just like C<< Class::MOP::Class->create >> but it
1321 creates an "anonymous" class. In fact, the class does have a name, but
1322 that name is a unique name generated internally by this module.
1324 It accepts the same C<superclasses>, C<methods>, and C<attributes>
1325 parameters that C<create> accepts.
1327 Anonymous classes are destroyed once the metaclass they are attached
1328 to goes out of scope, and will be removed from Perl's internal symbol
1331 All instances of an anonymous class keep a special reference to the
1332 metaclass object, which prevents the metaclass from going out of scope
1333 while any instances exist.
1335 This only works if the instance if based on a hash reference, however.
1337 =item B<< Class::MOP::Class->initialize($package_name, %options) >>
1339 This method will initialize a C<Class::MOP::Class> object for the
1340 named package. Unlike C<create>, this method I<will not> create a new
1343 The purpose of this method is to retrieve a C<Class::MOP::Class>
1344 object for introspecting an existing class.
1346 If an existing C<Class::MOP::Class> object exists for the named
1347 package, it will be returned, and any options provided will be
1350 If the object does not yet exist, it will be created.
1352 The valid options that can be passed to this method are
1353 C<attribute_metaclass>, C<method_metaclass>,
1354 C<wrapped_method_metaclass>, and C<instance_metaclass>. These are all
1355 optional, and default to the appropriate class in the C<Class::MOP>
1360 =head2 Object instance construction and cloning
1362 These methods are all related to creating and/or cloning object
1367 =item B<< $metaclass->clone_object($instance, %params) >>
1369 This method clones an existing object instance. Any parameters you
1370 provide are will override existing attribute values in the object.
1372 This is a convenience method for cloning an object instance, then
1373 blessing it into the appropriate package.
1375 You could implement a clone method in your class, using this method:
1378 my ($self, %params) = @_;
1379 $self->meta->clone_object($self, %params);
1382 =item B<< $metaclass->rebless_instance($instance, %params) >>
1384 This method changes the class of C<$instance> to the metaclass's class.
1386 You can only rebless an instance into a subclass of its current
1387 class. If you pass any additional parameters, these will be treated
1388 like constructor parameters and used to initialize the object's
1389 attributes. Any existing attributes that are already set will be
1392 Before reblessing the instance, this method will call
1393 C<rebless_instance_away> on the instance's current metaclass. This method
1394 will be passed the instance, the new metaclass, and any parameters
1395 specified to C<rebless_instance>. By default, C<rebless_instance_away>
1396 does nothing; it is merely a hook.
1398 =item B<< $metaclass->new_object(%params) >>
1400 This method is used to create a new object of the metaclass's
1401 class. Any parameters you provide are used to initialize the
1402 instance's attributes.
1404 =item B<< $metaclass->instance_metaclass >>
1406 Returns the class name of the instance metaclass, see
1407 L<Class::MOP::Instance> for more information on the instance
1410 =item B<< $metaclass->get_meta_instance >>
1412 Returns an instance of the C<instance_metaclass> to be used in the
1413 construction of a new instance of the class.
1417 =head2 Informational predicates
1419 These are a few predicate methods for asking information about the
1424 =item B<< $metaclass->is_anon_class >>
1426 This returns true if the class was created by calling C<<
1427 Class::MOP::Class->create_anon_class >>.
1429 =item B<< $metaclass->is_mutable >>
1431 This returns true if the class is still mutable.
1433 =item B<< $metaclass->is_immutable >>
1435 This returns true if the class has been made immutable.
1437 =item B<< $metaclass->is_pristine >>
1439 A class is I<not> pristine if it has non-inherited attributes or if it
1440 has any generated methods.
1444 =head2 Inheritance Relationships
1448 =item B<< $metaclass->superclasses(@superclasses) >>
1450 This is a read-write accessor which represents the superclass
1451 relationships of the metaclass's class.
1453 This is basically sugar around getting and setting C<@ISA>.
1455 =item B<< $metaclass->class_precedence_list >>
1457 This returns a list of all of the class's ancestor classes. The
1458 classes are returned in method dispatch order.
1460 =item B<< $metaclass->linearized_isa >>
1462 This returns a list based on C<class_precedence_list> but with all
1465 =item B<< $metaclass->subclasses >>
1467 This returns a list of all subclasses for this class, even indirect
1470 =item B<< $metaclass->direct_subclasses >>
1472 This returns a list of immediate subclasses for this class, which does not
1473 include indirect subclasses.
1477 =head2 Method introspection and creation
1479 These methods allow you to introspect a class's methods, as well as
1480 add, remove, or change methods.
1482 Determining what is truly a method in a Perl 5 class requires some
1483 heuristics (aka guessing).
1485 Methods defined outside the package with a fully qualified name (C<sub
1486 Package::name { ... }>) will be included. Similarly, methods named
1487 with a fully qualified name using L<Sub::Name> are also included.
1489 However, we attempt to ignore imported functions.
1491 Ultimately, we are using heuristics to determine what truly is a
1492 method in a class, and these heuristics may get the wrong answer in
1493 some edge cases. However, for most "normal" cases the heuristics work
1498 =item B<< $metaclass->get_method($method_name) >>
1500 This will return a L<Class::MOP::Method> for the specified
1501 C<$method_name>. If the class does not have the specified method, it
1504 =item B<< $metaclass->has_method($method_name) >>
1506 Returns a boolean indicating whether or not the class defines the
1507 named method. It does not include methods inherited from parent
1510 =item B<< $metaclass->get_method_map >>
1512 Returns a hash reference representing the methods defined in this
1513 class. The keys are method names and the values are
1514 L<Class::MOP::Method> objects.
1516 =item B<< $metaclass->get_method_list >>
1518 This will return a list of method I<names> for all methods defined in
1521 =item B<< $metaclass->get_all_methods >>
1523 This will traverse the inheritance hierarchy and return a list of all
1524 the L<Class::MOP::Method> objects for this class and its parents.
1526 =item B<< $metaclass->find_method_by_name($method_name) >>
1528 This will return a L<Class::MOP::Method> for the specified
1529 C<$method_name>. If the class does not have the specified method, it
1532 Unlike C<get_method>, this method I<will> look for the named method in
1535 =item B<< $metaclass->get_all_method_names >>
1537 This will return a list of method I<names> for all of this class's
1538 methods, including inherited methods.
1540 =item B<< $metaclass->find_all_methods_by_name($method_name) >>
1542 This method looks for the named method in the class and all of its
1543 parents. It returns every matching method it finds in the inheritance
1544 tree, so it returns a list of methods.
1546 Each method is returned as a hash reference with three keys. The keys
1547 are C<name>, C<class>, and C<code>. The C<code> key has a
1548 L<Class::MOP::Method> object as its value.
1550 The list of methods is distinct.
1552 =item B<< $metaclass->find_next_method_by_name($method_name) >>
1554 This method returns the first method in any superclass matching the
1555 given name. It is effectively the method that C<SUPER::$method_name>
1558 =item B<< $metaclass->add_method($method_name, $method) >>
1560 This method takes a method name and a subroutine reference, and adds
1561 the method to the class.
1563 The subroutine reference can be a L<Class::MOP::Method>, and you are
1564 strongly encouraged to pass a meta method object instead of a code
1565 reference. If you do so, that object gets stored as part of the
1566 class's method map directly. If not, the meta information will have to
1567 be recreated later, and may be incorrect.
1569 If you provide a method object, this method will clone that object if
1570 the object's package name does not match the class name. This lets us
1571 track the original source of any methods added from other classes
1572 (notably Moose roles).
1574 =item B<< $metaclass->remove_method($method_name) >>
1576 Remove the named method from the class. This method returns the
1577 L<Class::MOP::Method> object for the method.
1579 =item B<< $metaclass->method_metaclass >>
1581 Returns the class name of the method metaclass, see
1582 L<Class::MOP::Method> for more information on the method metaclass.
1584 =item B<< $metaclass->wrapped_method_metaclass >>
1586 Returns the class name of the wrapped method metaclass, see
1587 L<Class::MOP::Method::Wrapped> for more information on the wrapped
1592 =head2 Attribute introspection and creation
1594 Because Perl 5 does not have a core concept of attributes in classes,
1595 we can only return information about attributes which have been added
1596 via this class's methods. We cannot discover information about
1597 attributes which are defined in terms of "regular" Perl 5 methods.
1601 =item B<< $metaclass->get_attribute($attribute_name) >>
1603 This will return a L<Class::MOP::Attribute> for the specified
1604 C<$attribute_name>. If the class does not have the specified
1605 attribute, it returns C<undef>
1607 =item B<< $metaclass->has_attribute($attribute_name) >>
1609 Returns a boolean indicating whether or not the class defines the
1610 named attribute. It does not include attributes inherited from parent
1613 =item B<< $metaclass->get_attribute_map >>
1615 Returns a hash reference representing the attributes defined in this
1616 class. The keys are attribute names and the values are
1617 L<Class::MOP::Attribute> objects.
1619 =item B<< $metaclass->get_attribute_list >>
1621 This will return a list of attributes I<names> for all attributes
1622 defined in this class.
1624 =item B<< $metaclass->get_all_attributes >>
1626 This will traverse the inheritance hierarchy and return a list of all
1627 the L<Class::MOP::Attribute> objects for this class and its parents.
1629 =item B<< $metaclass->find_attribute_by_name($attribute_name) >>
1631 This will return a L<Class::MOP::Attribute> for the specified
1632 C<$attribute_name>. If the class does not have the specified
1633 attribute, it returns C<undef>
1635 Unlike C<get_attribute>, this attribute I<will> look for the named
1636 attribute in superclasses.
1638 =item B<< $metaclass->add_attribute(...) >>
1640 This method accepts either an existing L<Class::MOP::Attribute>
1641 object, or parameters suitable for passing to that class's C<new>
1644 The attribute provided will be added to the class.
1646 Any accessor methods defined by the attribute will be added to the
1647 class when the attribute is added.
1649 If an attribute of the same name already exists, the old attribute
1650 will be removed first.
1652 =item B<< $metaclass->remove_attribute($attribute_name) >>
1654 This will remove the named attribute from the class, and
1655 L<Class::MOP::Attribute> object.
1657 Removing an attribute also removes any accessor methods defined by the
1660 However, note that removing an attribute will only affect I<future>
1661 object instances created for this class, not existing instances.
1663 =item B<< $metaclass->attribute_metaclass >>
1665 Returns the class name of the attribute metaclass for this class. By
1666 default, this is L<Class::MOP::Attribute>. for more information on
1670 =head2 Class Immutability
1672 Making a class immutable "freezes" the class definition. You can no
1673 longer call methods which alter the class, such as adding or removing
1674 methods or attributes.
1676 Making a class immutable lets us optimize the class by inlining some
1677 methods, and also allows us to optimize some methods on the metaclass
1680 The immutabilization system in L<Moose> takes much greater advantage
1681 of the inlining features than Class::MOP itself does.
1685 =item B<< $metaclass->make_immutable(%options) >>
1687 This method will create an immutable transformer and uses it to make
1688 the class and its metaclass object immutable.
1690 Details of how immutabilization works are in L<Class::MOP::Immutable>
1693 =item B<< $metaclass->make_mutable >>
1695 Calling this method reverse the immutabilization transformation.
1697 =item B<< $metaclass->immutable_transformer >>
1699 If the class has been made immutable previously, this returns the
1700 L<Class::MOP::Immutable> object that was created to do the
1703 If the class was never made immutable, this method will die.
1707 =head2 Method Modifiers
1709 Method modifiers are hooks which allow a method to be wrapped with
1710 I<before>, I<after> and I<around> method modifiers. Every time a
1711 method is called, it's modifiers are also called.
1713 A class can modify its own methods, as well as methods defined in
1716 =head3 How method modifiers work?
1718 Method modifiers work by wrapping the original method and then
1719 replacing it in the class's symbol table. The wrappers will handle
1720 calling all the modifiers in the appropriate order and preserving the
1721 calling context for the original method.
1723 The return values of C<before> and C<after> modifiers are
1724 ignored. This is because their purpose is B<not> to filter the input
1725 and output of the primary method (this is done with an I<around>
1728 This may seem like an odd restriction to some, but doing this allows
1729 for simple code to be added at the beginning or end of a method call
1730 without altering the function of the wrapped method or placing any
1731 extra responsibility on the code of the modifier.
1733 Of course if you have more complex needs, you can use the C<around>
1734 modifier which allows you to change both the parameters passed to the
1735 wrapped method, as well as its return value.
1737 Before and around modifiers are called in last-defined-first-called
1738 order, while after modifiers are called in first-defined-first-called
1739 order. So the call tree might looks something like this:
1751 =head3 What is the performance impact?
1753 Of course there is a performance cost associated with method
1754 modifiers, but we have made every effort to make that cost directly
1755 proportional to the number of modifier features you utilize.
1757 The wrapping method does it's best to B<only> do as much work as it
1758 absolutely needs to. In order to do this we have moved some of the
1759 performance costs to set-up time, where they are easier to amortize.
1761 All this said, our benchmarks have indicated the following:
1763 simple wrapper with no modifiers 100% slower
1764 simple wrapper with simple before modifier 400% slower
1765 simple wrapper with simple after modifier 450% slower
1766 simple wrapper with simple around modifier 500-550% slower
1767 simple wrapper with all 3 modifiers 1100% slower
1769 These numbers may seem daunting, but you must remember, every feature
1770 comes with some cost. To put things in perspective, just doing a
1771 simple C<AUTOLOAD> which does nothing but extract the name of the
1772 method called and return it costs about 400% over a normal method
1777 =item B<< $metaclass->add_before_method_modifier($method_name, $code) >>
1779 This wraps the specified method with the supplied subroutine
1780 reference. The modifier will be called as a method itself, and will
1781 receive the same arguments as are passed to the method.
1783 When the modifier exits, the wrapped method will be called.
1785 The return value of the modifier will be ignored.
1787 =item B<< $metaclass->add_after_method_modifier($method_name, $code) >>
1789 This wraps the specified method with the supplied subroutine
1790 reference. The modifier will be called as a method itself, and will
1791 receive the same arguments as are passed to the method.
1793 When the wrapped methods exits, the modifier will be called.
1795 The return value of the modifier will be ignored.
1797 =item B<< $metaclass->add_around_method_modifier($method_name, $code) >>
1799 This wraps the specified method with the supplied subroutine
1802 The first argument passed to the modifier will be a subroutine
1803 reference to the wrapped method. The second argument is the object,
1804 and after that come any arguments passed when the method is called.
1806 The around modifier can choose to call the original method, as well as
1807 what arguments to pass if it does so.
1809 The return value of the modifier is what will be seen by the caller.
1813 =head2 Introspection
1817 =item B<< Class::MOP::Class->meta >>
1819 This will return a L<Class::MOP::Class> instance for this class.
1821 It should also be noted that L<Class::MOP> will actually bootstrap
1822 this module by installing a number of attribute meta-objects into its
1829 Stevan Little E<lt>stevan@iinteractive.comE<gt>
1831 =head1 COPYRIGHT AND LICENSE
1833 Copyright 2006-2009 by Infinity Interactive, Inc.
1835 L<http://www.iinteractive.com>
1837 This library is free software; you can redistribute it and/or modify
1838 it under the same terms as Perl itself.