2 package Class::MOP::Class;
7 use Class::MOP::Immutable;
8 use Class::MOP::Instance;
9 use Class::MOP::Method::Wrapped;
12 use Scalar::Util 'blessed', 'weaken';
14 our $VERSION = '0.78';
15 $VERSION = eval $VERSION;
16 our $AUTHORITY = 'cpan:STEVAN';
18 use base 'Class::MOP::Module';
28 $package_name = shift;
31 $package_name = $options{package};
34 (defined $package_name && $package_name && !ref($package_name))
35 || confess "You must pass a package name and it cannot be blessed";
37 return Class::MOP::get_metaclass_by_name($package_name)
38 || $class->_construct_class_instance(package => $package_name, @_);
41 sub construct_class_instance {
42 warn 'The construct_class_instance method has been made private.'
43 . " The public version is deprecated and will be removed in a future release.\n";
44 goto &_construct_class_instance;
47 # NOTE: (meta-circularity)
48 # this is a special form of &construct_instance
49 # (see below), which is used to construct class
50 # meta-object instances for any Class::MOP::*
51 # class. All other classes will use the more
52 # normal &construct_instance.
53 sub _construct_class_instance {
55 my $options = @_ == 1 ? $_[0] : {@_};
56 my $package_name = $options->{package};
57 (defined $package_name && $package_name)
58 || confess "You must pass a package name";
60 # return the metaclass if we have it cached,
61 # and it is still defined (it has not been
62 # reaped by DESTROY yet, which can happen
63 # annoyingly enough during global destruction)
65 if (defined(my $meta = Class::MOP::get_metaclass_by_name($package_name))) {
70 # we need to deal with the possibility
71 # of class immutability here, and then
72 # get the name of the class appropriately
74 ? ($class->is_immutable
75 ? $class->get_mutable_metaclass_name()
79 # now create the metaclass
81 if ($class eq 'Class::MOP::Class') {
83 $meta = $class->_new($options)
87 # it is safe to use meta here because
88 # class will always be a subclass of
89 # Class::MOP::Class, which defines meta
90 $meta = $class->meta->construct_instance($options)
93 # and check the metaclass compatibility
94 $meta->_check_metaclass_compatibility();
96 Class::MOP::store_metaclass_by_name($package_name, $meta);
99 # we need to weaken any anon classes
100 # so that they can call DESTROY properly
101 Class::MOP::weaken_metaclass($package_name) if $meta->is_anon_class;
108 my $options = @_ == 1 ? $_[0] : {@_};
111 # inherited from Class::MOP::Package
112 'package' => $options->{package},
115 # since the following attributes will
116 # actually be loaded from the symbol
117 # table, and actually bypass the instance
118 # entirely, we can just leave these things
119 # listed here for reference, because they
120 # should not actually have a value associated
122 'namespace' => \undef,
124 # inherited from Class::MOP::Module
126 'authority' => \undef,
128 # defined in Class::MOP::Class
129 'superclasses' => \undef,
133 'attribute_metaclass' => $options->{'attribute_metaclass'}
134 || 'Class::MOP::Attribute',
135 'method_metaclass' => $options->{'method_metaclass'}
136 || 'Class::MOP::Method',
137 'wrapped_method_metaclass' => $options->{'wrapped_method_metaclass'}
138 || 'Class::MOP::Method::Wrapped',
139 'instance_metaclass' => $options->{'instance_metaclass'}
140 || 'Class::MOP::Instance',
144 sub reset_package_cache_flag { (shift)->{'_package_cache_flag'} = undef }
145 sub update_package_cache_flag {
148 # we can manually update the cache number
149 # since we are actually adding the method
150 # to our cache as well. This avoids us
151 # having to regenerate the method_map.
153 $self->{'_package_cache_flag'} = Class::MOP::check_package_cache_flag($self->name);
157 sub check_metaclass_compatibility {
158 warn 'The check_metaclass_compatibility method has been made private.'
159 . " The public version is deprecated and will be removed in a future release.\n";
160 goto &_check_metaclass_compatibility;
163 sub _check_metaclass_compatibility {
166 # this is always okay ...
167 return if ref($self) eq 'Class::MOP::Class' &&
168 $self->instance_metaclass eq 'Class::MOP::Instance';
170 my @class_list = $self->linearized_isa;
171 shift @class_list; # shift off $self->name
173 foreach my $superclass_name (@class_list) {
174 my $super_meta = Class::MOP::get_metaclass_by_name($superclass_name) || next;
177 # we need to deal with the possibility
178 # of class immutability here, and then
179 # get the name of the class appropriately
181 = $super_meta->is_immutable
182 ? $super_meta->get_mutable_metaclass_name()
185 ($self->isa($super_meta_type))
186 || confess $self->name . "->meta => (" . (ref($self)) . ")" .
187 " is not compatible with the " .
188 $superclass_name . "->meta => (" . ($super_meta_type) . ")";
190 # we also need to check that instance metaclasses
191 # are compatibile in the same the class.
192 ($self->instance_metaclass->isa($super_meta->instance_metaclass))
193 || confess $self->name . "->meta->instance_metaclass => (" . ($self->instance_metaclass) . ")" .
194 " is not compatible with the " .
195 $superclass_name . "->meta->instance_metaclass => (" . ($super_meta->instance_metaclass) . ")";
203 # this should be sufficient, if you have a
204 # use case where it is not, write a test and
206 my $ANON_CLASS_SERIAL = 0;
209 # we need a sufficiently annoying prefix
210 # this should suffice for now, this is
211 # used in a couple of places below, so
212 # need to put it up here for now.
213 my $ANON_CLASS_PREFIX = 'Class::MOP::Class::__ANON__::SERIAL::';
217 no warnings 'uninitialized';
218 $self->name =~ /^$ANON_CLASS_PREFIX/;
221 sub create_anon_class {
222 my ($class, %options) = @_;
223 my $package_name = $ANON_CLASS_PREFIX . ++$ANON_CLASS_SERIAL;
224 return $class->create($package_name, %options);
228 # this will only get called for
229 # anon-classes, all other calls
230 # are assumed to occur during
231 # global destruction and so don't
232 # really need to be handled explicitly
236 return if Class::MOP::in_global_destruction(); # it'll happen soon anyway and this just makes things more complicated
238 no warnings 'uninitialized';
239 return unless $self->name =~ /^$ANON_CLASS_PREFIX/;
240 # Moose does a weird thing where it replaces the metaclass for
241 # class when fixing metaclass incompatibility. In that case,
242 # we don't want to clean out the namespace now. We can detect
243 # that because Moose will explicitly update the singleton
244 # cache in Class::MOP.
245 my $current_meta = Class::MOP::get_metaclass_by_name($self->name);
246 return if $current_meta ne $self;
248 my ($serial_id) = ($self->name =~ /^$ANON_CLASS_PREFIX(\d+)/);
250 foreach my $key (keys %{$ANON_CLASS_PREFIX . $serial_id}) {
251 delete ${$ANON_CLASS_PREFIX . $serial_id}{$key};
253 delete ${'main::' . $ANON_CLASS_PREFIX}{$serial_id . '::'};
258 # creating classes with MOP ...
261 my ( $class, @args ) = @_;
263 unshift @args, 'package' if @args % 2 == 1;
265 my (%options) = @args;
266 my $package_name = $options{package};
268 (ref $options{superclasses} eq 'ARRAY')
269 || confess "You must pass an ARRAY ref of superclasses"
270 if exists $options{superclasses};
272 (ref $options{attributes} eq 'ARRAY')
273 || confess "You must pass an ARRAY ref of attributes"
274 if exists $options{attributes};
276 (ref $options{methods} eq 'HASH')
277 || confess "You must pass a HASH ref of methods"
278 if exists $options{methods};
280 my (%initialize_options) = @args;
281 delete @initialize_options{qw(
289 my $meta = $class->initialize( $package_name => %initialize_options );
291 $meta->_instantiate_module( $options{version}, $options{authority} );
294 $meta->add_method('meta' => sub {
295 $class->initialize(ref($_[0]) || $_[0]);
298 $meta->superclasses(@{$options{superclasses}})
299 if exists $options{superclasses};
301 # process attributes first, so that they can
302 # install accessors, but locally defined methods
303 # can then overwrite them. It is maybe a little odd, but
304 # I think this should be the order of things.
305 if (exists $options{attributes}) {
306 foreach my $attr (@{$options{attributes}}) {
307 $meta->add_attribute($attr);
310 if (exists $options{methods}) {
311 foreach my $method_name (keys %{$options{methods}}) {
312 $meta->add_method($method_name, $options{methods}->{$method_name});
321 # all these attribute readers will be bootstrapped
322 # away in the Class::MOP bootstrap section
324 sub get_attribute_map { $_[0]->{'attributes'} }
325 sub attribute_metaclass { $_[0]->{'attribute_metaclass'} }
326 sub method_metaclass { $_[0]->{'method_metaclass'} }
327 sub wrapped_method_metaclass { $_[0]->{'wrapped_method_metaclass'} }
328 sub instance_metaclass { $_[0]->{'instance_metaclass'} }
330 # Instance Construction & Cloning
336 # we need to protect the integrity of the
337 # Class::MOP::Class singletons here, so we
338 # delegate this to &construct_class_instance
339 # which will deal with the singletons
340 return $class->_construct_class_instance(@_)
341 if $class->name->isa('Class::MOP::Class');
342 return $class->construct_instance(@_);
345 sub construct_instance {
347 my $params = @_ == 1 ? $_[0] : {@_};
348 my $meta_instance = $class->get_meta_instance();
349 my $instance = $meta_instance->create_instance();
350 foreach my $attr ($class->compute_all_applicable_attributes()) {
351 $attr->initialize_instance_slot($meta_instance, $instance, $params);
354 # this will only work for a HASH instance type
355 if ($class->is_anon_class) {
356 (Scalar::Util::reftype($instance) eq 'HASH')
357 || confess "Currently only HASH based instances are supported with instance of anon-classes";
359 # At some point we should make this official
360 # as a reserved slot name, but right now I am
361 # going to keep it here.
362 # my $RESERVED_MOP_SLOT = '__MOP__';
363 $instance->{'__MOP__'} = $class;
369 sub get_meta_instance {
371 $self->{'_meta_instance'} ||= $self->_create_meta_instance();
374 sub create_meta_instance {
375 warn 'The create_meta_instance method has been made private.'
376 . " The public version is deprecated and will be removed in a future release.\n";
377 goto &_create_meta_instance;
380 sub _create_meta_instance {
383 my $instance = $self->instance_metaclass->new(
384 associated_metaclass => $self,
385 attributes => [ $self->compute_all_applicable_attributes() ],
388 $self->add_meta_instance_dependencies()
389 if $instance->is_dependent_on_superclasses();
396 my $instance = shift;
397 (blessed($instance) && $instance->isa($class->name))
398 || confess "You must pass an instance of the metaclass (" . (ref $class ? $class->name : $class) . "), not ($instance)";
401 # we need to protect the integrity of the
402 # Class::MOP::Class singletons here, they
403 # should not be cloned.
404 return $instance if $instance->isa('Class::MOP::Class');
405 $class->_clone_instance($instance, @_);
409 warn 'The clone_instance method has been made private.'
410 . " The public version is deprecated and will be removed in a future release.\n";
411 goto &_clone_instance;
414 sub _clone_instance {
415 my ($class, $instance, %params) = @_;
417 || confess "You can only clone instances, ($instance) is not a blessed instance";
418 my $meta_instance = $class->get_meta_instance();
419 my $clone = $meta_instance->clone_instance($instance);
420 foreach my $attr ($class->compute_all_applicable_attributes()) {
421 if ( defined( my $init_arg = $attr->init_arg ) ) {
422 if (exists $params{$init_arg}) {
423 $attr->set_value($clone, $params{$init_arg});
430 sub rebless_instance {
431 my ($self, $instance, %params) = @_;
434 if ($instance->can('meta')) {
435 ($instance->meta->isa('Class::MOP::Class'))
436 || confess 'Cannot rebless instance if ->meta is not an instance of Class::MOP::Class';
437 $old_metaclass = $instance->meta;
440 $old_metaclass = $self->initialize(ref($instance));
443 my $meta_instance = $self->get_meta_instance();
445 $self->name->isa($old_metaclass->name)
446 || confess "You may rebless only into a subclass of (". $old_metaclass->name ."), of which (". $self->name .") isn't.";
449 # we use $_[1] here because of t/306_rebless_overload.t regressions on 5.8.8
450 $meta_instance->rebless_instance_structure($_[1], $self);
452 foreach my $attr ( $self->compute_all_applicable_attributes ) {
453 if ( $attr->has_value($instance) ) {
454 if ( defined( my $init_arg = $attr->init_arg ) ) {
455 $params{$init_arg} = $attr->get_value($instance)
456 unless exists $params{$init_arg};
459 $attr->set_value($instance, $attr->get_value($instance));
464 foreach my $attr ($self->compute_all_applicable_attributes) {
465 $attr->initialize_instance_slot($meta_instance, $instance, \%params);
475 my $var_spec = { sigil => '@', type => 'ARRAY', name => 'ISA' };
478 @{$self->get_package_symbol($var_spec)} = @supers;
481 # on 5.8 and below, we need to call
482 # a method to get Perl to detect
483 # a cycle in the class hierarchy
484 my $class = $self->name;
488 # we need to check the metaclass
489 # compatibility here so that we can
490 # be sure that the superclass is
491 # not potentially creating an issues
492 # we don't know about
494 $self->_check_metaclass_compatibility();
495 $self->update_meta_instance_dependencies();
497 @{$self->get_package_symbol($var_spec)};
503 my $super_class = $self->name;
505 if ( Class::MOP::HAVE_ISAREV() ) {
506 return @{ $super_class->mro::get_isarev() };
510 my $find_derived_classes;
511 $find_derived_classes = sub {
512 my ($outer_class) = @_;
514 my $symbol_table_hashref = do { no strict 'refs'; \%{"${outer_class}::"} };
517 for my $symbol ( keys %$symbol_table_hashref ) {
518 next SYMBOL if $symbol !~ /\A (\w+):: \z/x;
519 my $inner_class = $1;
521 next SYMBOL if $inner_class eq 'SUPER'; # skip '*::SUPER'
525 ? "${outer_class}::$inner_class"
528 if ( $class->isa($super_class) and $class ne $super_class ) {
529 push @derived_classes, $class;
532 next SYMBOL if $class eq 'main'; # skip 'main::*'
534 $find_derived_classes->($class);
538 my $root_class = q{};
539 $find_derived_classes->($root_class);
541 undef $find_derived_classes;
543 @derived_classes = sort { $a->isa($b) ? 1 : $b->isa($a) ? -1 : 0 } @derived_classes;
545 return @derived_classes;
551 return @{ mro::get_linear_isa( (shift)->name ) };
554 sub class_precedence_list {
556 my $name = $self->name;
558 unless (Class::MOP::IS_RUNNING_ON_5_10()) {
560 # We need to check for circular inheritance here
561 # if we are are not on 5.10, cause 5.8 detects it
562 # late. This will do nothing if all is well, and
563 # blow up otherwise. Yes, it's an ugly hack, better
564 # suggestions are welcome.
566 ($name || return)->isa('This is a test for circular inheritance')
569 # if our mro is c3, we can
570 # just grab the linear_isa
571 if (mro::get_mro($name) eq 'c3') {
572 return @{ mro::get_linear_isa($name) }
576 # we can't grab the linear_isa for dfs
577 # since it has all the duplicates
582 $self->initialize($_)->class_precedence_list()
583 } $self->superclasses()
590 sub wrap_method_body {
591 my ( $self, %args ) = @_;
593 ('CODE' eq ref $args{body})
594 || confess "Your code block must be a CODE reference";
596 $self->method_metaclass->wrap(
597 package_name => $self->name,
603 my ($self, $method_name, $method) = @_;
604 (defined $method_name && $method_name)
605 || confess "You must define a method name";
608 if (blessed($method)) {
609 $body = $method->body;
610 if ($method->package_name ne $self->name) {
611 $method = $method->clone(
612 package_name => $self->name,
614 ) if $method->can('clone');
619 $method = $self->wrap_method_body( body => $body, name => $method_name );
622 $method->attach_to_class($self);
624 # This used to call get_method_map, which meant we would build all
625 # the method objects for the class just because we added one
626 # method. This is hackier, but quicker too.
627 $self->{methods}{$method_name} = $method;
629 my $full_method_name = ($self->name . '::' . $method_name);
630 $self->add_package_symbol(
631 { sigil => '&', type => 'CODE', name => $method_name },
632 Class::MOP::subname($full_method_name => $body)
637 my $fetch_and_prepare_method = sub {
638 my ($self, $method_name) = @_;
639 my $wrapped_metaclass = $self->wrapped_method_metaclass;
641 my $method = $self->get_method($method_name);
642 # if we dont have local ...
644 # try to find the next method
645 $method = $self->find_next_method_by_name($method_name);
646 # die if it does not exist
648 || confess "The method '$method_name' was not found in the inheritance hierarchy for " . $self->name;
649 # and now make sure to wrap it
650 # even if it is already wrapped
651 # because we need a new sub ref
652 $method = $wrapped_metaclass->wrap($method);
655 # now make sure we wrap it properly
656 $method = $wrapped_metaclass->wrap($method)
657 unless $method->isa($wrapped_metaclass);
659 $self->add_method($method_name => $method);
663 sub add_before_method_modifier {
664 my ($self, $method_name, $method_modifier) = @_;
665 (defined $method_name && $method_name)
666 || confess "You must pass in a method name";
667 my $method = $fetch_and_prepare_method->($self, $method_name);
668 $method->add_before_modifier(
669 Class::MOP::subname(':before' => $method_modifier)
673 sub add_after_method_modifier {
674 my ($self, $method_name, $method_modifier) = @_;
675 (defined $method_name && $method_name)
676 || confess "You must pass in a method name";
677 my $method = $fetch_and_prepare_method->($self, $method_name);
678 $method->add_after_modifier(
679 Class::MOP::subname(':after' => $method_modifier)
683 sub add_around_method_modifier {
684 my ($self, $method_name, $method_modifier) = @_;
685 (defined $method_name && $method_name)
686 || confess "You must pass in a method name";
687 my $method = $fetch_and_prepare_method->($self, $method_name);
688 $method->add_around_modifier(
689 Class::MOP::subname(':around' => $method_modifier)
694 # the methods above used to be named like this:
695 # ${pkg}::${method}:(before|after|around)
696 # but this proved problematic when using one modifier
697 # to wrap multiple methods (something which is likely
698 # to happen pretty regularly IMO). So instead of naming
699 # it like this, I have chosen to just name them purely
700 # with their modifier names, like so:
701 # :(before|after|around)
702 # The fact is that in a stack trace, it will be fairly
703 # evident from the context what method they are attached
704 # to, and so don't need the fully qualified name.
708 warn "The alias_method method is deprecated. Use add_method instead.\n";
714 my ($self, $method_name) = @_;
715 (defined $method_name && $method_name)
716 || confess "You must define a method name";
718 exists $self->{methods}{$method_name} || exists $self->get_method_map->{$method_name};
722 my ($self, $method_name) = @_;
723 (defined $method_name && $method_name)
724 || confess "You must define a method name";
726 return $self->{methods}{$method_name} || $self->get_method_map->{$method_name};
730 my ($self, $method_name) = @_;
731 (defined $method_name && $method_name)
732 || confess "You must define a method name";
734 my $removed_method = delete $self->get_method_map->{$method_name};
736 $self->remove_package_symbol(
737 { sigil => '&', type => 'CODE', name => $method_name }
740 $removed_method->detach_from_class if $removed_method;
742 $self->update_package_cache_flag; # still valid, since we just removed the method from the map
744 return $removed_method;
747 sub get_method_list {
749 keys %{$self->get_method_map};
752 sub find_method_by_name {
753 my ($self, $method_name) = @_;
754 (defined $method_name && $method_name)
755 || confess "You must define a method name to find";
756 foreach my $class ($self->linearized_isa) {
757 # fetch the meta-class ...
758 my $meta = $self->initialize($class);
759 return $meta->get_method($method_name)
760 if $meta->has_method($method_name);
765 sub get_all_methods {
767 my %methods = map { %{ $self->initialize($_)->get_method_map } } reverse $self->linearized_isa;
768 return values %methods;
771 sub compute_all_applicable_methods {
772 warn 'The compute_all_applicable_methods method is deprecated.'
773 . " Use get_all_methods instead.\n";
778 class => $_->package_name,
779 code => $_, # sigh, overloading
781 } shift->get_all_methods(@_);
784 sub get_all_method_names {
787 grep { $uniq{$_}++ == 0 } map { $_->name } $self->get_all_methods;
790 sub find_all_methods_by_name {
791 my ($self, $method_name) = @_;
792 (defined $method_name && $method_name)
793 || confess "You must define a method name to find";
795 foreach my $class ($self->linearized_isa) {
796 # fetch the meta-class ...
797 my $meta = $self->initialize($class);
799 name => $method_name,
801 code => $meta->get_method($method_name)
802 } if $meta->has_method($method_name);
807 sub find_next_method_by_name {
808 my ($self, $method_name) = @_;
809 (defined $method_name && $method_name)
810 || confess "You must define a method name to find";
811 my @cpl = $self->linearized_isa;
812 shift @cpl; # discard ourselves
813 foreach my $class (@cpl) {
814 # fetch the meta-class ...
815 my $meta = $self->initialize($class);
816 return $meta->get_method($method_name)
817 if $meta->has_method($method_name);
826 # either we have an attribute object already
827 # or we need to create one from the args provided
828 my $attribute = blessed($_[0]) ? $_[0] : $self->attribute_metaclass->new(@_);
829 # make sure it is derived from the correct type though
830 ($attribute->isa('Class::MOP::Attribute'))
831 || confess "Your attribute must be an instance of Class::MOP::Attribute (or a subclass)";
833 # first we attach our new attribute
834 # because it might need certain information
835 # about the class which it is attached to
836 $attribute->attach_to_class($self);
838 # then we remove attributes of a conflicting
839 # name here so that we can properly detach
840 # the old attr object, and remove any
841 # accessors it would have generated
842 if ( $self->has_attribute($attribute->name) ) {
843 $self->remove_attribute($attribute->name);
845 $self->invalidate_meta_instances();
848 # then onto installing the new accessors
849 $self->get_attribute_map->{$attribute->name} = $attribute;
851 # invalidate package flag here
852 my $e = do { local $@; eval { $attribute->install_accessors() }; $@ };
854 $self->remove_attribute($attribute->name);
861 sub update_meta_instance_dependencies {
864 if ( $self->{meta_instance_dependencies} ) {
865 return $self->add_meta_instance_dependencies;
869 sub add_meta_instance_dependencies {
872 $self->remove_meta_instance_dependencies;
874 my @attrs = $self->compute_all_applicable_attributes();
877 my @classes = grep { not $seen{$_->name}++ } map { $_->associated_class } @attrs;
879 foreach my $class ( @classes ) {
880 $class->add_dependent_meta_instance($self);
883 $self->{meta_instance_dependencies} = \@classes;
886 sub remove_meta_instance_dependencies {
889 if ( my $classes = delete $self->{meta_instance_dependencies} ) {
890 foreach my $class ( @$classes ) {
891 $class->remove_dependent_meta_instance($self);
901 sub add_dependent_meta_instance {
902 my ( $self, $metaclass ) = @_;
903 push @{ $self->{dependent_meta_instances} }, $metaclass;
906 sub remove_dependent_meta_instance {
907 my ( $self, $metaclass ) = @_;
908 my $name = $metaclass->name;
909 @$_ = grep { $_->name ne $name } @$_ for $self->{dependent_meta_instances};
912 sub invalidate_meta_instances {
914 $_->invalidate_meta_instance() for $self, @{ $self->{dependent_meta_instances} };
917 sub invalidate_meta_instance {
919 undef $self->{_meta_instance};
923 my ($self, $attribute_name) = @_;
924 (defined $attribute_name && $attribute_name)
925 || confess "You must define an attribute name";
926 exists $self->get_attribute_map->{$attribute_name};
930 my ($self, $attribute_name) = @_;
931 (defined $attribute_name && $attribute_name)
932 || confess "You must define an attribute name";
933 return $self->get_attribute_map->{$attribute_name}
935 # this will return undef anyway, so no need ...
936 # if $self->has_attribute($attribute_name);
940 sub remove_attribute {
941 my ($self, $attribute_name) = @_;
942 (defined $attribute_name && $attribute_name)
943 || confess "You must define an attribute name";
944 my $removed_attribute = $self->get_attribute_map->{$attribute_name};
945 return unless defined $removed_attribute;
946 delete $self->get_attribute_map->{$attribute_name};
947 $self->invalidate_meta_instances();
948 $removed_attribute->remove_accessors();
949 $removed_attribute->detach_from_class();
950 return $removed_attribute;
953 sub get_attribute_list {
955 keys %{$self->get_attribute_map};
958 sub get_all_attributes {
959 shift->compute_all_applicable_attributes(@_);
962 sub compute_all_applicable_attributes {
964 my %attrs = map { %{ $self->initialize($_)->get_attribute_map } } reverse $self->linearized_isa;
965 return values %attrs;
968 sub find_attribute_by_name {
969 my ($self, $attr_name) = @_;
970 foreach my $class ($self->linearized_isa) {
971 # fetch the meta-class ...
972 my $meta = $self->initialize($class);
973 return $meta->get_attribute($attr_name)
974 if $meta->has_attribute($attr_name);
979 # check if we can reinitialize
983 # if any local attr is defined
984 return if $self->get_attribute_list;
986 # or any non-declared methods
987 if ( my @methods = values %{ $self->get_method_map } ) {
988 my $metaclass = $self->method_metaclass;
989 foreach my $method ( @methods ) {
990 return if $method->isa("Class::MOP::Method::Generated");
991 # FIXME do we need to enforce this too? return unless $method->isa($metaclass);
1000 sub is_mutable { 1 }
1001 sub is_immutable { 0 }
1004 # Why I changed this (groditi)
1005 # - One Metaclass may have many Classes through many Metaclass instances
1006 # - One Metaclass should only have one Immutable Transformer instance
1007 # - Each Class may have different Immutabilizing options
1008 # - Therefore each Metaclass instance may have different Immutabilizing options
1009 # - We need to store one Immutable Transformer instance per Metaclass
1010 # - We need to store one set of Immutable Transformer options per Class
1011 # - Upon make_mutable we may delete the Immutabilizing options
1012 # - We could clean the immutable Transformer instance when there is no more
1013 # immutable Classes of that type, but we can also keep it in case
1014 # another class with this same Metaclass becomes immutable. It is a case
1015 # of trading of storing an instance to avoid unnecessary instantiations of
1016 # Immutable Transformers. You may view this as a memory leak, however
1017 # Because we have few Metaclasses, in practice it seems acceptable
1018 # - To allow Immutable Transformers instances to be cleaned up we could weaken
1019 # the reference stored in $IMMUTABLE_TRANSFORMERS{$class} and ||= should DWIM
1023 my %IMMUTABLE_TRANSFORMERS;
1024 my %IMMUTABLE_OPTIONS;
1026 sub get_immutable_options {
1028 return if $self->is_mutable;
1029 confess "unable to find immutabilizing options"
1030 unless exists $IMMUTABLE_OPTIONS{$self->name};
1031 my %options = %{$IMMUTABLE_OPTIONS{$self->name}};
1032 delete $options{IMMUTABLE_TRANSFORMER};
1036 sub get_immutable_transformer {
1038 if( $self->is_mutable ){
1039 return $IMMUTABLE_TRANSFORMERS{$self->name} ||= $self->create_immutable_transformer;
1041 confess "unable to find transformer for immutable class"
1042 unless exists $IMMUTABLE_OPTIONS{$self->name};
1043 return $IMMUTABLE_OPTIONS{$self->name}->{IMMUTABLE_TRANSFORMER};
1046 sub make_immutable {
1050 my $transformer = $self->get_immutable_transformer;
1051 $transformer->make_metaclass_immutable($self, \%options);
1052 $IMMUTABLE_OPTIONS{$self->name} =
1053 { %options, IMMUTABLE_TRANSFORMER => $transformer };
1055 if( exists $options{debug} && $options{debug} ){
1056 print STDERR "# of Metaclass options: ", keys %IMMUTABLE_OPTIONS;
1057 print STDERR "# of Immutable transformers: ", keys %IMMUTABLE_TRANSFORMERS;
1065 return if $self->is_mutable;
1066 my $options = delete $IMMUTABLE_OPTIONS{$self->name};
1067 confess "unable to find immutabilizing options" unless ref $options;
1068 my $transformer = delete $options->{IMMUTABLE_TRANSFORMER};
1069 $transformer->make_metaclass_mutable($self, $options);
1074 sub create_immutable_transformer {
1076 my $class = Class::MOP::Immutable->new($self, {
1077 read_only => [qw/superclasses/],
1084 remove_package_symbol
1087 class_precedence_list => 'ARRAY',
1088 linearized_isa => 'ARRAY', # FIXME perl 5.10 memoizes this on its own, no need?
1089 get_all_methods => 'ARRAY',
1090 get_all_method_names => 'ARRAY',
1091 #get_all_attributes => 'ARRAY', # it's an alias, no need, but maybe in the future
1092 compute_all_applicable_attributes => 'ARRAY',
1093 get_meta_instance => 'SCALAR',
1094 get_method_map => 'SCALAR',
1097 # this is ugly, but so are typeglobs,
1098 # so whattayahgonnadoboutit
1101 add_package_symbol => sub {
1102 my $original = shift;
1103 confess "Cannot add package symbols to an immutable metaclass"
1104 unless (caller(2))[3] eq 'Class::MOP::Package::get_package_symbol';
1106 # This is a workaround for a bug in 5.8.1 which thinks that
1107 # goto $original->body
1108 # is trying to go to a label
1109 my $body = $original->body;
1125 Class::MOP::Class - Class Meta Object
1129 # assuming that class Foo
1130 # has been defined, you can
1132 # use this for introspection ...
1134 # add a method to Foo ...
1135 Foo->meta->add_method( 'bar' => sub {...} )
1137 # get a list of all the classes searched
1138 # the method dispatcher in the correct order
1139 Foo->meta->class_precedence_list()
1141 # remove a method from Foo
1142 Foo->meta->remove_method('bar');
1144 # or use this to actually create classes ...
1146 Class::MOP::Class->create(
1149 superclasses => ['Foo'],
1151 Class::MOP:: : Attribute->new('$bar'),
1152 Class::MOP:: : Attribute->new('$baz'),
1155 calculate_bar => sub {...},
1156 construct_baz => sub {...}
1163 The Class Protocol is the largest and most complex part of the
1164 Class::MOP meta-object protocol. It controls the introspection and
1165 manipulation of Perl 5 classes, and it can create them as well. The
1166 best way to understand what this module can do, is to read the
1167 documentation for each of its methods.
1171 C<Class::MOP::Class> is a subclass of L<Class::MOP::Module>.
1175 =head2 Class construction
1177 These methods all create new C<Class::MOP::Class> objects. These
1178 objects can represent existing classes, or they can be used to create
1179 new classes from scratch.
1181 The metaclass object for a given class is a singleton. If you attempt
1182 to create a metaclass for the same class twice, you will just get the
1187 =item B<< Class::MOP::Class->create($package_name, %options) >>
1189 This method creates a new C<Class::MOP::Class> object with the given
1190 package name. It accepts a number of options.
1196 An optional version number for the newly created package.
1200 An optional authority for the newly created package.
1202 =item * superclasses
1204 An optional array reference of superclass names.
1208 An optional hash reference of methods for the class. The keys of the
1209 hash reference are method names, and values are subroutine references.
1213 An optional array reference of attributes.
1215 An attribute can be passed as an existing L<Class::MOP::Attribute>
1216 object, I<or> or as a hash reference of options which will be passed
1217 to the attribute metaclass's constructor.
1221 =item B<< Class::MOP::Class->create_anon_class(%options) >>
1223 This method works just like C<< Class::MOP::Class->create >> but it
1224 creates an "anonymous" class. In fact, the class does have a name, but
1225 that name is a unique name generated internally by this module.
1227 It accepts the same C<superclasses>, C<methods>, and C<attributes>
1228 parameters that C<create> accepts.
1230 Anonymous classes are destroyed once the metaclass they are attached
1231 to goes out of scope, and will be removed from Perl's internal symbol
1234 All instances of an anonymous class keep a special reference to the
1235 metaclass object, which prevents the metaclass from going out of scope
1236 while any instances exist.
1238 This only works if the instance if based on a hash reference, however.
1240 =item B<< Class::MOP::Class->initialize($package_name, %options) >>
1242 This method will initialize a C<Class::MOP::Class> object for the
1243 named package. Unlike C<create>, this method I<will not> create a new
1246 The purpose of this method is to retrieve a C<Class::MOP::Class>
1247 object for introspecting an existing class.
1249 If an existing C<Class::MOP::Class> object exists for the named
1250 package, it will be returned, and any options provided will be
1253 If the object does not yet exist, it will be created.
1255 The valid options that can be passed to this method are
1256 C<attribute_metaclass>, C<method_metaclass>,
1257 C<wrapped_method_metaclass>, and C<instance_metaclass>. These are all
1258 optional, and default to the appropriate class in the C<Class::MOP>
1263 =head2 Object instance construction and cloning
1265 These methods are all related to creating and/or cloning object
1270 =item B<< $metaclass->clone_object($instance, %params) >>
1272 This method clones an existing object instance. Any parameters you
1273 provide are will override existing attribute values in the object.
1275 This is a convenience method for cloning an object instance, then
1276 blessing it into the appropriate package.
1278 You could implement a clone method in your class, using this method:
1281 my ($self, %params) = @_;
1282 $self->meta->clone_object($self, %params);
1285 =item B<< $metaclass->rebless_instance($instance, %params) >>
1287 This method changes the class of C<$instance> to the metaclass's class.
1289 You can only rebless an instance into a subclass of its current
1290 class. If you pass any additional parameters, these will be treated
1291 like constructor parameters and used to initialize the object's
1292 attributes. Any existing attributes that are already set will be
1295 =item B<< $metaclass->new_object(%params) >>
1297 This method is used to create a new object of the metaclass's
1298 class. Any parameters you provide are used to initialize the
1299 instance's attributes.
1301 =item B<< $metaclass->instance_metaclass >>
1303 Returns the class name of the instance metaclass, see
1304 L<Class::MOP::Instance> for more information on the instance
1307 =item B<< $metaclass->get_meta_instance >>
1309 Returns an instance of the C<instance_metaclass> to be used in the
1310 construction of a new instance of the class.
1314 =head2 Informational predicates
1316 These are a few predicate methods for asking information about the
1321 =item B<< $metaclass->is_anon_class >>
1323 This returns true if the class was created by calling C<<
1324 Class::MOP::Class->create_anon_class >>.
1326 =item B<< $metaclass->is_mutable >>
1328 This returns true if the class is still mutable.
1330 =item B<< $metaclass->is_immutable >>
1332 This returns true if the class has been made immutable.
1334 =item B<< $metaclass->is_pristine >>
1336 A class is I<not> pristine if it has non-inherited attributes or if it
1337 has any generated methods.
1341 =head2 Inheritance Relationships
1345 =item B<< $metaclass->superclasses(@superclasses) >>
1347 This is a read-write accessor which represents the superclass
1348 relationships of the metaclass's class.
1350 This is basically sugar around getting and setting C<@ISA>.
1352 =item B<< $metaclass->class_precedence_list >>
1354 This returns a list of all of the class's ancestor classes. The
1355 classes are returned in method dispatch order.
1357 =item B<< $metaclass->linearized_isa >>
1359 This returns a list based on C<class_precedence_list> but with all
1362 =item B<< $metaclass->subclasses >>
1364 This returns a list of subclasses for this class.
1368 =head2 Method introspection and creation
1370 These methods allow you to introspect a class's methods, as well as
1371 add, remove, or change methods.
1373 Determining what is truly a method in a Perl 5 class requires some
1374 heuristics (aka guessing).
1376 Methods defined outside the package with a fully qualified name (C<sub
1377 Package::name { ... }>) will be included. Similarly, methods named
1378 with a fully qualified name using L<Sub::Name> are also included.
1380 However, we attempt to ignore imported functions.
1382 Ultimately, we are using heuristics to determine what truly is a
1383 method in a class, and these heuristics may get the wrong answer in
1384 some edge cases. However, for most "normal" cases the heuristics work
1389 =item B<< $metaclass->get_method($method_name) >>
1391 This will return a L<Class::MOP::Method> for the specified
1392 C<$method_name>. If the class does not have the specified method, it
1395 =item B<< $metaclass->has_method($method_name) >>
1397 Returns a boolean indicating whether or not the class defines the
1398 named method. It does not include methods inherited from parent
1401 =item B<< $metaclass->get_method_map >>
1403 Returns a hash reference representing the methods defined in this
1404 class. The keys are method names and the values are
1405 L<Class::MOP::Method> objects.
1407 =item B<< $metaclass->get_method_list >>
1409 This will return a list of method I<names> for all methods defined in
1412 =item B<< $metaclass->get_all_methods >>
1414 This will traverse the inheritance hierarchy and return a list of all
1415 the L<Class::MOP::Method> objects for this class and its parents.
1417 =item B<< $metaclass->find_method_by_name($method_name) >>
1419 This will return a L<Class::MOP::Method> for the specified
1420 C<$method_name>. If the class does not have the specified method, it
1423 Unlike C<get_method>, this method I<will> look for the named method in
1426 =item B<< $metaclass->get_all_method_names >>
1428 This will return a list of method I<names> for all of this class's
1429 methods, including inherited methods.
1431 =item B<< $metaclass->find_all_methods_by_name($method_name) >>
1433 This method looks for the named method in the class and all of its
1434 parents. It returns every matching method it finds in the inheritance
1435 tree, so it returns a list of methods.
1437 Each method is returned as a hash reference with three keys. The keys
1438 are C<name>, C<class>, and C<code>. The C<code> key has a
1439 L<Class::MOP::Method> object as its value.
1441 The list of methods is distinct.
1443 =item B<< $metaclass->find_next_method_by_name($method_name) >>
1445 This method returns the first method in any superclass matching the
1446 given name. It is effectively the method that C<SUPER::$method_name>
1449 =item B<< $metaclass->add_method($method_name, $method) >>
1451 This method takes a method name and a subroutine reference, and adds
1452 the method to the class.
1454 The subroutine reference can be a L<Class::MOP::Method>, and you are
1455 strongly encouraged to pass a meta method object instead of a code
1456 reference. If you do so, that object gets stored as part of the
1457 class's method map directly. If not, the meta information will have to
1458 be recreated later, and may be incorrect.
1460 If you provide a method object, this method will clone that object if
1461 the object's package name does not match the class name. This lets us
1462 track the original source of any methods added from other classes
1463 (notably Moose roles).
1465 =item B<< $metaclass->remove_method($method_name) >>
1467 Remove the named method from the class. This method returns the
1468 L<Class::MOP::Method> object for the method.
1470 =item B<< $metaclass->method_metaclass >>
1472 Returns the class name of the method metaclass, see
1473 L<Class::MOP::Method> for more information on the method metaclass.
1475 =item B<< $metaclass->wrapped_method_metaclass >>
1477 Returns the class name of the wrapped method metaclass, see
1478 L<Class::MOP::Method::Wrapped> for more information on the wrapped
1483 =head2 Attribute introspection and creation
1485 Because Perl 5 does not have a core concept of attributes in classes,
1486 we can only return information about attributes which have been added
1487 via this class's methods. We cannot discover information about
1488 attributes which are defined in terms of "regular" Perl 5 methods.
1492 =item B<< $metaclass->get_attribute($attribute_name) >>
1494 This will return a L<Class::MOP::Attribute> for the specified
1495 C<$attribute_name>. If the class does not have the specified
1496 attribute, it returns C<undef>
1498 =item B<< $metaclass->has_attribute($attribute_name) >>
1500 Returns a boolean indicating whether or not the class defines the
1501 named attribute. It does not include attributes inherited from parent
1504 =item B<< $metaclass->get_attribute_map >>
1506 Returns a hash reference representing the attributes defined in this
1507 class. The keys are attribute names and the values are
1508 L<Class::MOP::Attribute> objects.
1510 =item B<< $metaclass->get_attribute_list >>
1512 This will return a list of attributes I<names> for all attributes
1513 defined in this class.
1515 =item B<< $metaclass->get_all_attributes >>
1517 This will traverse the inheritance hierarchy and return a list of all
1518 the L<Class::MOP::Attribute> objects for this class and its parents.
1520 This method can also be called as C<compute_all_applicable_attributes>.
1522 =item B<< $metaclass->find_attribute_by_name($attribute_name) >>
1524 This will return a L<Class::MOP::Attribute> for the specified
1525 C<$attribute_name>. If the class does not have the specified
1526 attribute, it returns C<undef>
1528 Unlike C<get_attribute>, this attribute I<will> look for the named
1529 attribute in superclasses.
1531 =item B<< $metaclass->add_attribute(...) >>
1533 This method accepts either an existing L<Class::MOP::Attribute>
1534 object, or parameters suitable for passing to that class's C<new>
1537 The attribute provided will be added to the class.
1539 Any accessor methods defined by the attribute will be added to the
1540 class when the attribute is added.
1542 If an attribute of the same name already exists, the old attribute
1543 will be removed first.
1545 =item B<< $metaclass->remove_attribute($attribute_name) >>
1547 This will remove the named attribute from the class, and
1548 L<Class::MOP::Attribute> object.
1550 Removing an attribute also removes any accessor methods defined by the
1553 However, note that removing an attribute will only affect I<future>
1554 object instances created for this class, not existing instances.
1556 =item B<< $metaclass->attribute_metaclass >>
1558 Returns the class name of the attribute metaclass for this class. By
1559 default, this is L<Class::MOP::Attribute>. for more information on
1563 =head2 Class Immutability
1565 Making a class immutable "freezes" the class definition. You can no
1566 longer call methods which alter the class, such as adding or removing
1567 methods or attributes.
1569 Making a class immutable lets us optimize the class by inlining some
1570 methods, and also allows us to optimize some methods on the metaclass
1573 The immutabilization system in L<Moose> takes much greater advantage
1574 of the inlining features than Class::MOP itself does.
1578 =item B<< $metaclass->make_immutable(%options) >>
1580 This method will create an immutable transformer and uses it to make
1581 the class and its metaclass object immutable.
1583 Details of how immutabilization works are in L<Class::MOP::Immutable>
1586 =item B<< $metaclass->make_mutable >>
1588 Calling this method reverse the immutabilization transformation.
1590 =item B<< $metaclass->get_immutable_transformer >>
1592 If the class has been made immutable previously, this returns the
1593 L<Class::MOP::Immutable> object that was created to do the
1596 If the class was never made immutable, this method will die.
1600 =head2 Method Modifiers
1602 Method modifiers are hooks which allow a method to be wrapped with
1603 I<before>, I<after> and I<around> method modifiers. Every time a
1604 method is called, it's modifiers are also called.
1606 A class can modify its own methods, as well as methods defined in
1609 =head3 How method modifiers work?
1611 Method modifiers work by wrapping the original method and then
1612 replacing it in the class's symbol table. The wrappers will handle
1613 calling all the modifiers in the appropriate order and preserving the
1614 calling context for the original method.
1616 The return values of C<before> and C<after> modifiers are
1617 ignored. This is because their purpose is B<not> to filter the input
1618 and output of the primary method (this is done with an I<around>
1621 This may seem like an odd restriction to some, but doing this allows
1622 for simple code to be added at the beginning or end of a method call
1623 without altering the function of the wrapped method or placing any
1624 extra responsibility on the code of the modifier.
1626 Of course if you have more complex needs, you can use the C<around>
1627 modifier which allows you to change both the parameters passed to the
1628 wrapped method, as well as its return value.
1630 Before and around modifiers are called in last-defined-first-called
1631 order, while after modifiers are called in first-defined-first-called
1632 order. So the call tree might looks something like this:
1644 =head3 What is the performance impact?
1646 Of course there is a performance cost associated with method
1647 modifiers, but we have made every effort to make that cost directly
1648 proportional to the number of modifier features you utilize.
1650 The wrapping method does it's best to B<only> do as much work as it
1651 absolutely needs to. In order to do this we have moved some of the
1652 performance costs to set-up time, where they are easier to amortize.
1654 All this said, our benchmarks have indicated the following:
1656 simple wrapper with no modifiers 100% slower
1657 simple wrapper with simple before modifier 400% slower
1658 simple wrapper with simple after modifier 450% slower
1659 simple wrapper with simple around modifier 500-550% slower
1660 simple wrapper with all 3 modifiers 1100% slower
1662 These numbers may seem daunting, but you must remember, every feature
1663 comes with some cost. To put things in perspective, just doing a
1664 simple C<AUTOLOAD> which does nothing but extract the name of the
1665 method called and return it costs about 400% over a normal method
1670 =item B<< $metaclass->add_before_method_modifier($method_name, $code) >>
1672 This wraps the specified method with the supplied subroutine
1673 reference. The modifier will be called as a method itself, and will
1674 receive the same arguments as are passed to the method.
1676 When the modifier exits, the wrapped method will be called.
1678 The return value of the modifier will be ignored.
1680 =item B<< $metaclass->add_after_method_modifier($method_name, $code) >>
1682 This wraps the specified method with the supplied subroutine
1683 reference. The modifier will be called as a method itself, and will
1684 receive the same arguments as are passed to the method.
1686 When the wrapped methods exits, the modifier will be called.
1688 The return value of the modifier will be ignored.
1690 =item B<< $metaclass->add_around_method_modifier($method_name, $code) >>
1692 This wraps the specified method with the supplied subroutine
1695 The first argument passed to the modifier will be a subroutine
1696 reference to the wrapped method. The second argument is the object,
1697 and after that come any arguments passed when the method is called.
1699 The around modifier can choose to call the original method, as well as
1700 what arguments to pass if it does so.
1702 The return value of the modifier is what will be seen by the caller.
1706 =head2 Introspection
1710 =item B<< Class::MOP::Class->meta >>
1712 This will return a L<Class::MOP::Class> instance for this class.
1714 It should also be noted that L<Class::MOP> will actually bootstrap
1715 this module by installing a number of attribute meta-objects into its
1722 Stevan Little E<lt>stevan@iinteractive.comE<gt>
1724 =head1 COPYRIGHT AND LICENSE
1726 Copyright 2006-2009 by Infinity Interactive, Inc.
1728 L<http://www.iinteractive.com>
1730 This library is free software; you can redistribute it and/or modify
1731 it under the same terms as Perl itself.