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 = '0.83';
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() };
534 return @{ mro::get_linear_isa( (shift)->name ) };
537 sub class_precedence_list {
539 my $name = $self->name;
541 unless (Class::MOP::IS_RUNNING_ON_5_10()) {
543 # We need to check for circular inheritance here
544 # if we are are not on 5.10, cause 5.8 detects it
545 # late. This will do nothing if all is well, and
546 # blow up otherwise. Yes, it's an ugly hack, better
547 # suggestions are welcome.
549 ($name || return)->isa('This is a test for circular inheritance')
552 # if our mro is c3, we can
553 # just grab the linear_isa
554 if (mro::get_mro($name) eq 'c3') {
555 return @{ mro::get_linear_isa($name) }
559 # we can't grab the linear_isa for dfs
560 # since it has all the duplicates
565 $self->initialize($_)->class_precedence_list()
566 } $self->superclasses()
573 sub wrap_method_body {
574 my ( $self, %args ) = @_;
576 ('CODE' eq ref $args{body})
577 || confess "Your code block must be a CODE reference";
579 $self->method_metaclass->wrap(
580 package_name => $self->name,
586 my ($self, $method_name, $method) = @_;
587 (defined $method_name && $method_name)
588 || confess "You must define a method name";
591 if (blessed($method)) {
592 $body = $method->body;
593 if ($method->package_name ne $self->name) {
594 $method = $method->clone(
595 package_name => $self->name,
597 ) if $method->can('clone');
602 $method = $self->wrap_method_body( body => $body, name => $method_name );
605 $method->attach_to_class($self);
607 # This used to call get_method_map, which meant we would build all
608 # the method objects for the class just because we added one
609 # method. This is hackier, but quicker too.
610 $self->{methods}{$method_name} = $method;
612 my $full_method_name = ($self->name . '::' . $method_name);
613 $self->add_package_symbol(
614 { sigil => '&', type => 'CODE', name => $method_name },
615 subname($full_method_name => $body)
620 my $fetch_and_prepare_method = sub {
621 my ($self, $method_name) = @_;
622 my $wrapped_metaclass = $self->wrapped_method_metaclass;
624 my $method = $self->get_method($method_name);
625 # if we dont have local ...
627 # try to find the next method
628 $method = $self->find_next_method_by_name($method_name);
629 # die if it does not exist
631 || confess "The method '$method_name' was not found in the inheritance hierarchy for " . $self->name;
632 # and now make sure to wrap it
633 # even if it is already wrapped
634 # because we need a new sub ref
635 $method = $wrapped_metaclass->wrap($method);
638 # now make sure we wrap it properly
639 $method = $wrapped_metaclass->wrap($method)
640 unless $method->isa($wrapped_metaclass);
642 $self->add_method($method_name => $method);
646 sub add_before_method_modifier {
647 my ($self, $method_name, $method_modifier) = @_;
648 (defined $method_name && $method_name)
649 || confess "You must pass in a method name";
650 my $method = $fetch_and_prepare_method->($self, $method_name);
651 $method->add_before_modifier(
652 subname(':before' => $method_modifier)
656 sub add_after_method_modifier {
657 my ($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_after_modifier(
662 subname(':after' => $method_modifier)
666 sub add_around_method_modifier {
667 my ($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_around_modifier(
672 subname(':around' => $method_modifier)
677 # the methods above used to be named like this:
678 # ${pkg}::${method}:(before|after|around)
679 # but this proved problematic when using one modifier
680 # to wrap multiple methods (something which is likely
681 # to happen pretty regularly IMO). So instead of naming
682 # it like this, I have chosen to just name them purely
683 # with their modifier names, like so:
684 # :(before|after|around)
685 # The fact is that in a stack trace, it will be fairly
686 # evident from the context what method they are attached
687 # to, and so don't need the fully qualified name.
691 Carp::cluck("The alias_method method is deprecated. Use add_method instead.\n");
693 shift->add_method(@_);
697 my ($self, $method_name) = @_;
698 (defined $method_name && $method_name)
699 || confess "You must define a method name";
701 exists $self->{methods}{$method_name} || exists $self->get_method_map->{$method_name};
705 my ($self, $method_name) = @_;
706 (defined $method_name && $method_name)
707 || confess "You must define a method name";
709 return $self->{methods}{$method_name} || $self->get_method_map->{$method_name};
713 my ($self, $method_name) = @_;
714 (defined $method_name && $method_name)
715 || confess "You must define a method name";
717 my $removed_method = delete $self->get_method_map->{$method_name};
719 $self->remove_package_symbol(
720 { sigil => '&', type => 'CODE', name => $method_name }
723 $removed_method->detach_from_class if $removed_method;
725 $self->update_package_cache_flag; # still valid, since we just removed the method from the map
727 return $removed_method;
730 sub get_method_list {
732 keys %{$self->get_method_map};
735 sub find_method_by_name {
736 my ($self, $method_name) = @_;
737 (defined $method_name && $method_name)
738 || confess "You must define a method name to find";
739 foreach my $class ($self->linearized_isa) {
740 # fetch the meta-class ...
741 my $meta = $self->initialize($class);
742 return $meta->get_method($method_name)
743 if $meta->has_method($method_name);
748 sub get_all_methods {
750 my %methods = map { %{ $self->initialize($_)->get_method_map } } reverse $self->linearized_isa;
751 return values %methods;
754 sub compute_all_applicable_methods {
755 Carp::cluck('The compute_all_applicable_methods method is deprecated.'
756 . " Use get_all_methods instead.\n");
761 class => $_->package_name,
762 code => $_, # sigh, overloading
764 } shift->get_all_methods(@_);
767 sub get_all_method_names {
770 grep { $uniq{$_}++ == 0 } map { $_->name } $self->get_all_methods;
773 sub find_all_methods_by_name {
774 my ($self, $method_name) = @_;
775 (defined $method_name && $method_name)
776 || confess "You must define a method name to find";
778 foreach my $class ($self->linearized_isa) {
779 # fetch the meta-class ...
780 my $meta = $self->initialize($class);
782 name => $method_name,
784 code => $meta->get_method($method_name)
785 } if $meta->has_method($method_name);
790 sub find_next_method_by_name {
791 my ($self, $method_name) = @_;
792 (defined $method_name && $method_name)
793 || confess "You must define a method name to find";
794 my @cpl = $self->linearized_isa;
795 shift @cpl; # discard ourselves
796 foreach my $class (@cpl) {
797 # fetch the meta-class ...
798 my $meta = $self->initialize($class);
799 return $meta->get_method($method_name)
800 if $meta->has_method($method_name);
809 # either we have an attribute object already
810 # or we need to create one from the args provided
811 my $attribute = blessed($_[0]) ? $_[0] : $self->attribute_metaclass->new(@_);
812 # make sure it is derived from the correct type though
813 ($attribute->isa('Class::MOP::Attribute'))
814 || confess "Your attribute must be an instance of Class::MOP::Attribute (or a subclass)";
816 # first we attach our new attribute
817 # because it might need certain information
818 # about the class which it is attached to
819 $attribute->attach_to_class($self);
821 # then we remove attributes of a conflicting
822 # name here so that we can properly detach
823 # the old attr object, and remove any
824 # accessors it would have generated
825 if ( $self->has_attribute($attribute->name) ) {
826 $self->remove_attribute($attribute->name);
828 $self->invalidate_meta_instances();
831 # get our count of previously inserted attributes and
832 # increment by one so this attribute knows its order
833 $attribute->insertion_order((scalar keys %{$self->get_attribute_map}) + 1);
835 # then onto installing the new accessors
836 $self->get_attribute_map->{$attribute->name} = $attribute;
838 # invalidate package flag here
839 my $e = do { local $@; eval { $attribute->install_accessors() }; $@ };
841 $self->remove_attribute($attribute->name);
848 sub update_meta_instance_dependencies {
851 if ( $self->{meta_instance_dependencies} ) {
852 return $self->add_meta_instance_dependencies;
856 sub add_meta_instance_dependencies {
859 $self->remove_meta_instance_dependencies;
861 my @attrs = $self->get_all_attributes();
864 my @classes = grep { not $seen{$_->name}++ } map { $_->associated_class } @attrs;
866 foreach my $class ( @classes ) {
867 $class->add_dependent_meta_instance($self);
870 $self->{meta_instance_dependencies} = \@classes;
873 sub remove_meta_instance_dependencies {
876 if ( my $classes = delete $self->{meta_instance_dependencies} ) {
877 foreach my $class ( @$classes ) {
878 $class->remove_dependent_meta_instance($self);
888 sub add_dependent_meta_instance {
889 my ( $self, $metaclass ) = @_;
890 push @{ $self->{dependent_meta_instances} }, $metaclass;
893 sub remove_dependent_meta_instance {
894 my ( $self, $metaclass ) = @_;
895 my $name = $metaclass->name;
896 @$_ = grep { $_->name ne $name } @$_ for $self->{dependent_meta_instances};
899 sub invalidate_meta_instances {
901 $_->invalidate_meta_instance() for $self, @{ $self->{dependent_meta_instances} };
904 sub invalidate_meta_instance {
906 undef $self->{_meta_instance};
910 my ($self, $attribute_name) = @_;
911 (defined $attribute_name && $attribute_name)
912 || confess "You must define an attribute name";
913 exists $self->get_attribute_map->{$attribute_name};
917 my ($self, $attribute_name) = @_;
918 (defined $attribute_name && $attribute_name)
919 || confess "You must define an attribute name";
920 return $self->get_attribute_map->{$attribute_name}
922 # this will return undef anyway, so no need ...
923 # if $self->has_attribute($attribute_name);
927 sub remove_attribute {
928 my ($self, $attribute_name) = @_;
929 (defined $attribute_name && $attribute_name)
930 || confess "You must define an attribute name";
931 my $removed_attribute = $self->get_attribute_map->{$attribute_name};
932 return unless defined $removed_attribute;
933 delete $self->get_attribute_map->{$attribute_name};
934 $self->invalidate_meta_instances();
935 $removed_attribute->remove_accessors();
936 $removed_attribute->detach_from_class();
937 return $removed_attribute;
940 sub get_attribute_list {
942 keys %{$self->get_attribute_map};
945 sub get_all_attributes {
947 my %attrs = map { %{ $self->initialize($_)->get_attribute_map } } reverse $self->linearized_isa;
948 return values %attrs;
951 sub compute_all_applicable_attributes {
952 Carp::cluck('The compute_all_applicable_attributes method has been deprecated.'
953 . " Use get_all_attributes instead.\n");
955 shift->get_all_attributes(@_);
958 sub find_attribute_by_name {
959 my ($self, $attr_name) = @_;
960 foreach my $class ($self->linearized_isa) {
961 # fetch the meta-class ...
962 my $meta = $self->initialize($class);
963 return $meta->get_attribute($attr_name)
964 if $meta->has_attribute($attr_name);
969 # check if we can reinitialize
973 # if any local attr is defined
974 return if $self->get_attribute_list;
976 # or any non-declared methods
977 if ( my @methods = values %{ $self->get_method_map } ) {
978 my $metaclass = $self->method_metaclass;
979 foreach my $method ( @methods ) {
980 return if $method->isa("Class::MOP::Method::Generated");
981 # FIXME do we need to enforce this too? return unless $method->isa($metaclass);
991 sub is_immutable { 0 }
992 sub immutable_transformer { return }
994 sub _immutable_options {
995 my ( $self, @args ) = @_;
998 inline_accessors => 1,
999 inline_constructor => 1,
1000 inline_destructor => 0,
1002 immutable_trait => $self->immutable_trait,
1003 constructor_name => $self->constructor_name,
1004 constructor_class => $self->constructor_class,
1005 destructor_class => $self->destructor_class,
1010 sub make_immutable {
1011 my ( $self, @args ) = @_;
1013 if ( $self->is_mutable ) {
1014 $self->_initialize_immutable( $self->_immutable_options(@args) );
1015 $self->_rebless_as_immutable(@args);
1026 if ( $self->is_immutable ) {
1027 my @args = $self->immutable_options;
1028 $self->_rebless_as_mutable();
1029 $self->_remove_inlined_code(@args);
1030 delete $self->{__immutable};
1038 sub _rebless_as_immutable {
1039 my ( $self, @args ) = @_;
1041 $self->{__immutable}{original_class} = ref $self;
1043 bless $self => $self->_immutable_metaclass(@args);
1046 sub _immutable_metaclass {
1047 my ( $self, %args ) = @_;
1049 if ( my $class = $args{immutable_metaclass} ) {
1053 my $trait = $args{immutable_trait} = $self->immutable_trait
1054 || confess "no immutable trait specified for $self";
1056 my $meta_attr = $self->meta->find_attribute_by_name("immutable_trait");
1060 if ( $meta_attr and $trait eq $meta_attr->default ) {
1062 # if the trait is the same as the default we try and pick a predictable
1063 # name for the immutable metaclass
1064 $class_name = "Class::MOP::Class::Immutable::" . ref($self);
1068 = join( "::", "Class::MOP::Class::Immutable::CustomTrait", $trait,
1069 "ForMetaClass", ref($self) );
1072 if ( Class::MOP::is_class_loaded($class_name) ) {
1073 if ( $class_name->isa($trait) ) {
1078 "$class_name is already defined but does not inherit $trait";
1082 my @super = ( $trait, ref($self) );
1084 my $meta = Class::MOP::Class->initialize($class_name);
1085 $meta->superclasses(@super);
1087 $meta->make_immutable;
1093 sub _remove_inlined_code {
1096 $self->remove_method( $_->name ) for $self->_inlined_methods;
1098 delete $self->{__immutable}{inlined_methods};
1101 sub _inlined_methods { @{ $_[0]{__immutable}{inlined_methods} || [] } }
1103 sub _add_inlined_method {
1104 my ( $self, $method ) = @_;
1106 push @{ $self->{__immutable}{inlined_methods} ||= [] }, $method;
1109 sub _initialize_immutable {
1110 my ( $self, %args ) = @_;
1112 $self->{__immutable}{options} = \%args;
1113 $self->_install_inlined_code(%args);
1116 sub _install_inlined_code {
1117 my ( $self, %args ) = @_;
1120 $self->_inline_accessors(%args) if $args{inline_accessors};
1121 $self->_inline_constructor(%args) if $args{inline_constructor};
1122 $self->_inline_destructor(%args) if $args{inline_destructor};
1125 sub _rebless_as_mutable {
1128 bless $self, $self->get_mutable_metaclass_name;
1133 sub _inline_accessors {
1136 foreach my $attr_name ( $self->get_attribute_list ) {
1137 $self->get_attribute($attr_name)->install_accessors(1);
1141 sub _inline_constructor {
1142 my ( $self, %args ) = @_;
1144 my $name = $args{constructor_name};
1146 #if ( my $existing = $self->name->can($args{constructor_name}) ) {
1147 # if ( refaddr($existing) == refaddr(\&Moose::Object::new) ) {
1149 unless ( $args{replace_constructor}
1150 or !$self->has_method($name) ) {
1151 my $class = $self->name;
1152 warn "Not inlining a constructor for $class since it defines"
1153 . " its own constructor.\n"
1154 . "If you are certain you don't need to inline your"
1155 . " constructor, specify inline_constructor => 0 in your"
1156 . " call to $class->meta->make_immutable\n";
1160 my $constructor_class = $args{constructor_class};
1162 Class::MOP::load_class($constructor_class);
1164 my $constructor = $constructor_class->new(
1168 package_name => $self->name,
1172 if ( $args{replace_constructor} or $constructor->can_be_inlined ) {
1173 $self->add_method( $name => $constructor );
1174 $self->_add_inlined_method($constructor);
1178 sub _inline_destructor {
1179 my ( $self, %args ) = @_;
1181 ( exists $args{destructor_class} )
1182 || confess "The 'inline_destructor' option is present, but "
1183 . "no destructor class was specified";
1185 my $destructor_class = $args{destructor_class};
1187 Class::MOP::load_class($destructor_class);
1189 return unless $destructor_class->is_needed($self);
1191 my $destructor = $destructor_class->new(
1194 package_name => $self->name,
1198 $self->add_method( 'DESTROY' => $destructor );
1200 $self->_add_inlined_method($destructor);
1211 Class::MOP::Class - Class Meta Object
1215 # assuming that class Foo
1216 # has been defined, you can
1218 # use this for introspection ...
1220 # add a method to Foo ...
1221 Foo->meta->add_method( 'bar' => sub {...} )
1223 # get a list of all the classes searched
1224 # the method dispatcher in the correct order
1225 Foo->meta->class_precedence_list()
1227 # remove a method from Foo
1228 Foo->meta->remove_method('bar');
1230 # or use this to actually create classes ...
1232 Class::MOP::Class->create(
1235 superclasses => ['Foo'],
1237 Class::MOP::Attribute->new('$bar'),
1238 Class::MOP::Attribute->new('$baz'),
1241 calculate_bar => sub {...},
1242 construct_baz => sub {...}
1249 The Class Protocol is the largest and most complex part of the
1250 Class::MOP meta-object protocol. It controls the introspection and
1251 manipulation of Perl 5 classes, and it can create them as well. The
1252 best way to understand what this module can do, is to read the
1253 documentation for each of its methods.
1257 C<Class::MOP::Class> is a subclass of L<Class::MOP::Module>.
1261 =head2 Class construction
1263 These methods all create new C<Class::MOP::Class> objects. These
1264 objects can represent existing classes, or they can be used to create
1265 new classes from scratch.
1267 The metaclass object for a given class is a singleton. If you attempt
1268 to create a metaclass for the same class twice, you will just get the
1273 =item B<< Class::MOP::Class->create($package_name, %options) >>
1275 This method creates a new C<Class::MOP::Class> object with the given
1276 package name. It accepts a number of options.
1282 An optional version number for the newly created package.
1286 An optional authority for the newly created package.
1288 =item * superclasses
1290 An optional array reference of superclass names.
1294 An optional hash reference of methods for the class. The keys of the
1295 hash reference are method names, and values are subroutine references.
1299 An optional array reference of attributes.
1301 An attribute can be passed as an existing L<Class::MOP::Attribute>
1302 object, I<or> or as a hash reference of options which will be passed
1303 to the attribute metaclass's constructor.
1307 =item B<< Class::MOP::Class->create_anon_class(%options) >>
1309 This method works just like C<< Class::MOP::Class->create >> but it
1310 creates an "anonymous" class. In fact, the class does have a name, but
1311 that name is a unique name generated internally by this module.
1313 It accepts the same C<superclasses>, C<methods>, and C<attributes>
1314 parameters that C<create> accepts.
1316 Anonymous classes are destroyed once the metaclass they are attached
1317 to goes out of scope, and will be removed from Perl's internal symbol
1320 All instances of an anonymous class keep a special reference to the
1321 metaclass object, which prevents the metaclass from going out of scope
1322 while any instances exist.
1324 This only works if the instance if based on a hash reference, however.
1326 =item B<< Class::MOP::Class->initialize($package_name, %options) >>
1328 This method will initialize a C<Class::MOP::Class> object for the
1329 named package. Unlike C<create>, this method I<will not> create a new
1332 The purpose of this method is to retrieve a C<Class::MOP::Class>
1333 object for introspecting an existing class.
1335 If an existing C<Class::MOP::Class> object exists for the named
1336 package, it will be returned, and any options provided will be
1339 If the object does not yet exist, it will be created.
1341 The valid options that can be passed to this method are
1342 C<attribute_metaclass>, C<method_metaclass>,
1343 C<wrapped_method_metaclass>, and C<instance_metaclass>. These are all
1344 optional, and default to the appropriate class in the C<Class::MOP>
1349 =head2 Object instance construction and cloning
1351 These methods are all related to creating and/or cloning object
1356 =item B<< $metaclass->clone_object($instance, %params) >>
1358 This method clones an existing object instance. Any parameters you
1359 provide are will override existing attribute values in the object.
1361 This is a convenience method for cloning an object instance, then
1362 blessing it into the appropriate package.
1364 You could implement a clone method in your class, using this method:
1367 my ($self, %params) = @_;
1368 $self->meta->clone_object($self, %params);
1371 =item B<< $metaclass->rebless_instance($instance, %params) >>
1373 This method changes the class of C<$instance> to the metaclass's class.
1375 You can only rebless an instance into a subclass of its current
1376 class. If you pass any additional parameters, these will be treated
1377 like constructor parameters and used to initialize the object's
1378 attributes. Any existing attributes that are already set will be
1381 Before reblessing the instance, this method will call
1382 C<rebless_instance_away> on the instance's current metaclass. This method
1383 will be passed the instance, the new metaclass, and any parameters
1384 specified to C<rebless_instance>. By default, C<rebless_instance_away>
1385 does nothing; it is merely a hook.
1387 =item B<< $metaclass->new_object(%params) >>
1389 This method is used to create a new object of the metaclass's
1390 class. Any parameters you provide are used to initialize the
1391 instance's attributes.
1393 =item B<< $metaclass->instance_metaclass >>
1395 Returns the class name of the instance metaclass, see
1396 L<Class::MOP::Instance> for more information on the instance
1399 =item B<< $metaclass->get_meta_instance >>
1401 Returns an instance of the C<instance_metaclass> to be used in the
1402 construction of a new instance of the class.
1406 =head2 Informational predicates
1408 These are a few predicate methods for asking information about the
1413 =item B<< $metaclass->is_anon_class >>
1415 This returns true if the class was created by calling C<<
1416 Class::MOP::Class->create_anon_class >>.
1418 =item B<< $metaclass->is_mutable >>
1420 This returns true if the class is still mutable.
1422 =item B<< $metaclass->is_immutable >>
1424 This returns true if the class has been made immutable.
1426 =item B<< $metaclass->is_pristine >>
1428 A class is I<not> pristine if it has non-inherited attributes or if it
1429 has any generated methods.
1433 =head2 Inheritance Relationships
1437 =item B<< $metaclass->superclasses(@superclasses) >>
1439 This is a read-write accessor which represents the superclass
1440 relationships of the metaclass's class.
1442 This is basically sugar around getting and setting C<@ISA>.
1444 =item B<< $metaclass->class_precedence_list >>
1446 This returns a list of all of the class's ancestor classes. The
1447 classes are returned in method dispatch order.
1449 =item B<< $metaclass->linearized_isa >>
1451 This returns a list based on C<class_precedence_list> but with all
1454 =item B<< $metaclass->subclasses >>
1456 This returns a list of subclasses for this class.
1460 =head2 Method introspection and creation
1462 These methods allow you to introspect a class's methods, as well as
1463 add, remove, or change methods.
1465 Determining what is truly a method in a Perl 5 class requires some
1466 heuristics (aka guessing).
1468 Methods defined outside the package with a fully qualified name (C<sub
1469 Package::name { ... }>) will be included. Similarly, methods named
1470 with a fully qualified name using L<Sub::Name> are also included.
1472 However, we attempt to ignore imported functions.
1474 Ultimately, we are using heuristics to determine what truly is a
1475 method in a class, and these heuristics may get the wrong answer in
1476 some edge cases. However, for most "normal" cases the heuristics work
1481 =item B<< $metaclass->get_method($method_name) >>
1483 This will return a L<Class::MOP::Method> for the specified
1484 C<$method_name>. If the class does not have the specified method, it
1487 =item B<< $metaclass->has_method($method_name) >>
1489 Returns a boolean indicating whether or not the class defines the
1490 named method. It does not include methods inherited from parent
1493 =item B<< $metaclass->get_method_map >>
1495 Returns a hash reference representing the methods defined in this
1496 class. The keys are method names and the values are
1497 L<Class::MOP::Method> objects.
1499 =item B<< $metaclass->get_method_list >>
1501 This will return a list of method I<names> for all methods defined in
1504 =item B<< $metaclass->get_all_methods >>
1506 This will traverse the inheritance hierarchy and return a list of all
1507 the L<Class::MOP::Method> objects for this class and its parents.
1509 =item B<< $metaclass->find_method_by_name($method_name) >>
1511 This will return a L<Class::MOP::Method> for the specified
1512 C<$method_name>. If the class does not have the specified method, it
1515 Unlike C<get_method>, this method I<will> look for the named method in
1518 =item B<< $metaclass->get_all_method_names >>
1520 This will return a list of method I<names> for all of this class's
1521 methods, including inherited methods.
1523 =item B<< $metaclass->find_all_methods_by_name($method_name) >>
1525 This method looks for the named method in the class and all of its
1526 parents. It returns every matching method it finds in the inheritance
1527 tree, so it returns a list of methods.
1529 Each method is returned as a hash reference with three keys. The keys
1530 are C<name>, C<class>, and C<code>. The C<code> key has a
1531 L<Class::MOP::Method> object as its value.
1533 The list of methods is distinct.
1535 =item B<< $metaclass->find_next_method_by_name($method_name) >>
1537 This method returns the first method in any superclass matching the
1538 given name. It is effectively the method that C<SUPER::$method_name>
1541 =item B<< $metaclass->add_method($method_name, $method) >>
1543 This method takes a method name and a subroutine reference, and adds
1544 the method to the class.
1546 The subroutine reference can be a L<Class::MOP::Method>, and you are
1547 strongly encouraged to pass a meta method object instead of a code
1548 reference. If you do so, that object gets stored as part of the
1549 class's method map directly. If not, the meta information will have to
1550 be recreated later, and may be incorrect.
1552 If you provide a method object, this method will clone that object if
1553 the object's package name does not match the class name. This lets us
1554 track the original source of any methods added from other classes
1555 (notably Moose roles).
1557 =item B<< $metaclass->remove_method($method_name) >>
1559 Remove the named method from the class. This method returns the
1560 L<Class::MOP::Method> object for the method.
1562 =item B<< $metaclass->method_metaclass >>
1564 Returns the class name of the method metaclass, see
1565 L<Class::MOP::Method> for more information on the method metaclass.
1567 =item B<< $metaclass->wrapped_method_metaclass >>
1569 Returns the class name of the wrapped method metaclass, see
1570 L<Class::MOP::Method::Wrapped> for more information on the wrapped
1575 =head2 Attribute introspection and creation
1577 Because Perl 5 does not have a core concept of attributes in classes,
1578 we can only return information about attributes which have been added
1579 via this class's methods. We cannot discover information about
1580 attributes which are defined in terms of "regular" Perl 5 methods.
1584 =item B<< $metaclass->get_attribute($attribute_name) >>
1586 This will return a L<Class::MOP::Attribute> for the specified
1587 C<$attribute_name>. If the class does not have the specified
1588 attribute, it returns C<undef>
1590 =item B<< $metaclass->has_attribute($attribute_name) >>
1592 Returns a boolean indicating whether or not the class defines the
1593 named attribute. It does not include attributes inherited from parent
1596 =item B<< $metaclass->get_attribute_map >>
1598 Returns a hash reference representing the attributes defined in this
1599 class. The keys are attribute names and the values are
1600 L<Class::MOP::Attribute> objects.
1602 =item B<< $metaclass->get_attribute_list >>
1604 This will return a list of attributes I<names> for all attributes
1605 defined in this class.
1607 =item B<< $metaclass->get_all_attributes >>
1609 This will traverse the inheritance hierarchy and return a list of all
1610 the L<Class::MOP::Attribute> objects for this class and its parents.
1612 =item B<< $metaclass->find_attribute_by_name($attribute_name) >>
1614 This will return a L<Class::MOP::Attribute> for the specified
1615 C<$attribute_name>. If the class does not have the specified
1616 attribute, it returns C<undef>
1618 Unlike C<get_attribute>, this attribute I<will> look for the named
1619 attribute in superclasses.
1621 =item B<< $metaclass->add_attribute(...) >>
1623 This method accepts either an existing L<Class::MOP::Attribute>
1624 object, or parameters suitable for passing to that class's C<new>
1627 The attribute provided will be added to the class.
1629 Any accessor methods defined by the attribute will be added to the
1630 class when the attribute is added.
1632 If an attribute of the same name already exists, the old attribute
1633 will be removed first.
1635 =item B<< $metaclass->remove_attribute($attribute_name) >>
1637 This will remove the named attribute from the class, and
1638 L<Class::MOP::Attribute> object.
1640 Removing an attribute also removes any accessor methods defined by the
1643 However, note that removing an attribute will only affect I<future>
1644 object instances created for this class, not existing instances.
1646 =item B<< $metaclass->attribute_metaclass >>
1648 Returns the class name of the attribute metaclass for this class. By
1649 default, this is L<Class::MOP::Attribute>. for more information on
1653 =head2 Class Immutability
1655 Making a class immutable "freezes" the class definition. You can no
1656 longer call methods which alter the class, such as adding or removing
1657 methods or attributes.
1659 Making a class immutable lets us optimize the class by inlining some
1660 methods, and also allows us to optimize some methods on the metaclass
1663 The immutabilization system in L<Moose> takes much greater advantage
1664 of the inlining features than Class::MOP itself does.
1668 =item B<< $metaclass->make_immutable(%options) >>
1670 This method will create an immutable transformer and uses it to make
1671 the class and its metaclass object immutable.
1673 Details of how immutabilization works are in L<Class::MOP::Immutable>
1676 =item B<< $metaclass->make_mutable >>
1678 Calling this method reverse the immutabilization transformation.
1680 =item B<< $metaclass->immutable_transformer >>
1682 If the class has been made immutable previously, this returns the
1683 L<Class::MOP::Immutable> object that was created to do the
1686 If the class was never made immutable, this method will die.
1690 =head2 Method Modifiers
1692 Method modifiers are hooks which allow a method to be wrapped with
1693 I<before>, I<after> and I<around> method modifiers. Every time a
1694 method is called, it's modifiers are also called.
1696 A class can modify its own methods, as well as methods defined in
1699 =head3 How method modifiers work?
1701 Method modifiers work by wrapping the original method and then
1702 replacing it in the class's symbol table. The wrappers will handle
1703 calling all the modifiers in the appropriate order and preserving the
1704 calling context for the original method.
1706 The return values of C<before> and C<after> modifiers are
1707 ignored. This is because their purpose is B<not> to filter the input
1708 and output of the primary method (this is done with an I<around>
1711 This may seem like an odd restriction to some, but doing this allows
1712 for simple code to be added at the beginning or end of a method call
1713 without altering the function of the wrapped method or placing any
1714 extra responsibility on the code of the modifier.
1716 Of course if you have more complex needs, you can use the C<around>
1717 modifier which allows you to change both the parameters passed to the
1718 wrapped method, as well as its return value.
1720 Before and around modifiers are called in last-defined-first-called
1721 order, while after modifiers are called in first-defined-first-called
1722 order. So the call tree might looks something like this:
1734 =head3 What is the performance impact?
1736 Of course there is a performance cost associated with method
1737 modifiers, but we have made every effort to make that cost directly
1738 proportional to the number of modifier features you utilize.
1740 The wrapping method does it's best to B<only> do as much work as it
1741 absolutely needs to. In order to do this we have moved some of the
1742 performance costs to set-up time, where they are easier to amortize.
1744 All this said, our benchmarks have indicated the following:
1746 simple wrapper with no modifiers 100% slower
1747 simple wrapper with simple before modifier 400% slower
1748 simple wrapper with simple after modifier 450% slower
1749 simple wrapper with simple around modifier 500-550% slower
1750 simple wrapper with all 3 modifiers 1100% slower
1752 These numbers may seem daunting, but you must remember, every feature
1753 comes with some cost. To put things in perspective, just doing a
1754 simple C<AUTOLOAD> which does nothing but extract the name of the
1755 method called and return it costs about 400% over a normal method
1760 =item B<< $metaclass->add_before_method_modifier($method_name, $code) >>
1762 This wraps the specified method with the supplied subroutine
1763 reference. The modifier will be called as a method itself, and will
1764 receive the same arguments as are passed to the method.
1766 When the modifier exits, the wrapped method will be called.
1768 The return value of the modifier will be ignored.
1770 =item B<< $metaclass->add_after_method_modifier($method_name, $code) >>
1772 This wraps the specified method with the supplied subroutine
1773 reference. The modifier will be called as a method itself, and will
1774 receive the same arguments as are passed to the method.
1776 When the wrapped methods exits, the modifier will be called.
1778 The return value of the modifier will be ignored.
1780 =item B<< $metaclass->add_around_method_modifier($method_name, $code) >>
1782 This wraps the specified method with the supplied subroutine
1785 The first argument passed to the modifier will be a subroutine
1786 reference to the wrapped method. The second argument is the object,
1787 and after that come any arguments passed when the method is called.
1789 The around modifier can choose to call the original method, as well as
1790 what arguments to pass if it does so.
1792 The return value of the modifier is what will be seen by the caller.
1796 =head2 Introspection
1800 =item B<< Class::MOP::Class->meta >>
1802 This will return a L<Class::MOP::Class> instance for this class.
1804 It should also be noted that L<Class::MOP> will actually bootstrap
1805 this module by installing a number of attribute meta-objects into its
1812 Stevan Little E<lt>stevan@iinteractive.comE<gt>
1814 =head1 COPYRIGHT AND LICENSE
1816 Copyright 2006-2009 by Infinity Interactive, Inc.
1818 L<http://www.iinteractive.com>
1820 This library is free software; you can redistribute it and/or modify
1821 it under the same terms as Perl itself.