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_02';
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 shift->_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') {
82 $meta = $class->_new($options);
86 # it is safe to use meta here because
87 # class will always be a subclass of
88 # Class::MOP::Class, which defines meta
89 $meta = $class->meta->construct_instance($options)
92 # and check the metaclass compatibility
93 $meta->_check_metaclass_compatibility();
95 Class::MOP::store_metaclass_by_name($package_name, $meta);
98 # we need to weaken any anon classes
99 # so that they can call DESTROY properly
100 Class::MOP::weaken_metaclass($package_name) if $meta->is_anon_class;
107 my $options = @_ == 1 ? $_[0] : {@_};
110 # inherited from Class::MOP::Package
111 'package' => $options->{package},
114 # since the following attributes will
115 # actually be loaded from the symbol
116 # table, and actually bypass the instance
117 # entirely, we can just leave these things
118 # listed here for reference, because they
119 # should not actually have a value associated
121 'namespace' => \undef,
123 # inherited from Class::MOP::Module
125 'authority' => \undef,
127 # defined in Class::MOP::Class
128 'superclasses' => \undef,
132 'attribute_metaclass' => $options->{'attribute_metaclass'}
133 || 'Class::MOP::Attribute',
134 'method_metaclass' => $options->{'method_metaclass'}
135 || 'Class::MOP::Method',
136 'wrapped_method_metaclass' => $options->{'wrapped_method_metaclass'}
137 || 'Class::MOP::Method::Wrapped',
138 'instance_metaclass' => $options->{'instance_metaclass'}
139 || 'Class::MOP::Instance',
143 sub reset_package_cache_flag { (shift)->{'_package_cache_flag'} = undef }
144 sub update_package_cache_flag {
147 # we can manually update the cache number
148 # since we are actually adding the method
149 # to our cache as well. This avoids us
150 # having to regenerate the method_map.
152 $self->{'_package_cache_flag'} = Class::MOP::check_package_cache_flag($self->name);
156 sub check_metaclass_compatibility {
157 warn 'The check_metaclass_compatibility method has been made private.'
158 . " The public version is deprecated and will be removed in a future release.\n";
159 shift->_check_metaclass_compatibility;
162 sub _check_metaclass_compatibility {
165 # this is always okay ...
166 return if ref($self) eq 'Class::MOP::Class' &&
167 $self->instance_metaclass eq 'Class::MOP::Instance';
169 my @class_list = $self->linearized_isa;
170 shift @class_list; # shift off $self->name
172 foreach my $superclass_name (@class_list) {
173 my $super_meta = Class::MOP::get_metaclass_by_name($superclass_name) || next;
176 # we need to deal with the possibility
177 # of class immutability here, and then
178 # get the name of the class appropriately
180 = $super_meta->is_immutable
181 ? $super_meta->get_mutable_metaclass_name()
184 ($self->isa($super_meta_type))
185 || confess $self->name . "->meta => (" . (ref($self)) . ")" .
186 " is not compatible with the " .
187 $superclass_name . "->meta => (" . ($super_meta_type) . ")";
189 # we also need to check that instance metaclasses
190 # are compatibile in the same the class.
191 ($self->instance_metaclass->isa($super_meta->instance_metaclass))
192 || confess $self->name . "->meta->instance_metaclass => (" . ($self->instance_metaclass) . ")" .
193 " is not compatible with the " .
194 $superclass_name . "->meta->instance_metaclass => (" . ($super_meta->instance_metaclass) . ")";
202 # this should be sufficient, if you have a
203 # use case where it is not, write a test and
205 my $ANON_CLASS_SERIAL = 0;
208 # we need a sufficiently annoying prefix
209 # this should suffice for now, this is
210 # used in a couple of places below, so
211 # need to put it up here for now.
212 my $ANON_CLASS_PREFIX = 'Class::MOP::Class::__ANON__::SERIAL::';
216 no warnings 'uninitialized';
217 $self->name =~ /^$ANON_CLASS_PREFIX/;
220 sub create_anon_class {
221 my ($class, %options) = @_;
222 my $package_name = $ANON_CLASS_PREFIX . ++$ANON_CLASS_SERIAL;
223 return $class->create($package_name, %options);
227 # this will only get called for
228 # anon-classes, all other calls
229 # are assumed to occur during
230 # global destruction and so don't
231 # really need to be handled explicitly
235 return if Class::MOP::in_global_destruction(); # it'll happen soon anyway and this just makes things more complicated
237 no warnings 'uninitialized';
238 return unless $self->name =~ /^$ANON_CLASS_PREFIX/;
239 # Moose does a weird thing where it replaces the metaclass for
240 # class when fixing metaclass incompatibility. In that case,
241 # we don't want to clean out the namespace now. We can detect
242 # that because Moose will explicitly update the singleton
243 # cache in Class::MOP.
244 my $current_meta = Class::MOP::get_metaclass_by_name($self->name);
245 return if $current_meta ne $self;
247 my ($serial_id) = ($self->name =~ /^$ANON_CLASS_PREFIX(\d+)/);
249 foreach my $key (keys %{$ANON_CLASS_PREFIX . $serial_id}) {
250 delete ${$ANON_CLASS_PREFIX . $serial_id}{$key};
252 delete ${'main::' . $ANON_CLASS_PREFIX}{$serial_id . '::'};
257 # creating classes with MOP ...
260 my ( $class, @args ) = @_;
262 unshift @args, 'package' if @args % 2 == 1;
264 my (%options) = @args;
265 my $package_name = $options{package};
267 (ref $options{superclasses} eq 'ARRAY')
268 || confess "You must pass an ARRAY ref of superclasses"
269 if exists $options{superclasses};
271 (ref $options{attributes} eq 'ARRAY')
272 || confess "You must pass an ARRAY ref of attributes"
273 if exists $options{attributes};
275 (ref $options{methods} eq 'HASH')
276 || confess "You must pass a HASH ref of methods"
277 if exists $options{methods};
279 my (%initialize_options) = @args;
280 delete @initialize_options{qw(
288 my $meta = $class->initialize( $package_name => %initialize_options );
290 $meta->_instantiate_module( $options{version}, $options{authority} );
293 $meta->add_method('meta' => sub {
294 $class->initialize(ref($_[0]) || $_[0]);
297 $meta->superclasses(@{$options{superclasses}})
298 if exists $options{superclasses};
300 # process attributes first, so that they can
301 # install accessors, but locally defined methods
302 # can then overwrite them. It is maybe a little odd, but
303 # I think this should be the order of things.
304 if (exists $options{attributes}) {
305 foreach my $attr (@{$options{attributes}}) {
306 $meta->add_attribute($attr);
309 if (exists $options{methods}) {
310 foreach my $method_name (keys %{$options{methods}}) {
311 $meta->add_method($method_name, $options{methods}->{$method_name});
320 # all these attribute readers will be bootstrapped
321 # away in the Class::MOP bootstrap section
323 sub get_attribute_map { $_[0]->{'attributes'} }
324 sub attribute_metaclass { $_[0]->{'attribute_metaclass'} }
325 sub method_metaclass { $_[0]->{'method_metaclass'} }
326 sub wrapped_method_metaclass { $_[0]->{'wrapped_method_metaclass'} }
327 sub instance_metaclass { $_[0]->{'instance_metaclass'} }
329 # Instance Construction & Cloning
335 # we need to protect the integrity of the
336 # Class::MOP::Class singletons here, so we
337 # delegate this to &construct_class_instance
338 # which will deal with the singletons
339 return $class->_construct_class_instance(@_)
340 if $class->name->isa('Class::MOP::Class');
341 return $class->construct_instance(@_);
344 sub construct_instance {
346 my $params = @_ == 1 ? $_[0] : {@_};
347 my $meta_instance = $class->get_meta_instance();
348 my $instance = $meta_instance->create_instance();
349 foreach my $attr ($class->compute_all_applicable_attributes()) {
350 $attr->initialize_instance_slot($meta_instance, $instance, $params);
353 # this will only work for a HASH instance type
354 if ($class->is_anon_class) {
355 (Scalar::Util::reftype($instance) eq 'HASH')
356 || confess "Currently only HASH based instances are supported with instance of anon-classes";
358 # At some point we should make this official
359 # as a reserved slot name, but right now I am
360 # going to keep it here.
361 # my $RESERVED_MOP_SLOT = '__MOP__';
362 $instance->{'__MOP__'} = $class;
368 sub get_meta_instance {
370 $self->{'_meta_instance'} ||= $self->_create_meta_instance();
373 sub create_meta_instance {
374 warn 'The create_meta_instance method has been made private.'
375 . " The public version is deprecated and will be removed in a future release.\n";
376 shift->_create_meta_instance;
379 sub _create_meta_instance {
382 my $instance = $self->instance_metaclass->new(
383 associated_metaclass => $self,
384 attributes => [ $self->compute_all_applicable_attributes() ],
387 $self->add_meta_instance_dependencies()
388 if $instance->is_dependent_on_superclasses();
395 my $instance = shift;
396 (blessed($instance) && $instance->isa($class->name))
397 || confess "You must pass an instance of the metaclass (" . (ref $class ? $class->name : $class) . "), not ($instance)";
400 # we need to protect the integrity of the
401 # Class::MOP::Class singletons here, they
402 # should not be cloned.
403 return $instance if $instance->isa('Class::MOP::Class');
404 $class->_clone_instance($instance, @_);
408 warn 'The clone_instance method has been made private.'
409 . " The public version is deprecated and will be removed in a future release.\n";
410 shift->_clone_instance;
413 sub _clone_instance {
414 my ($class, $instance, %params) = @_;
416 || confess "You can only clone instances, ($instance) is not a blessed instance";
417 my $meta_instance = $class->get_meta_instance();
418 my $clone = $meta_instance->clone_instance($instance);
419 foreach my $attr ($class->compute_all_applicable_attributes()) {
420 if ( defined( my $init_arg = $attr->init_arg ) ) {
421 if (exists $params{$init_arg}) {
422 $attr->set_value($clone, $params{$init_arg});
429 sub rebless_instance {
430 my ($self, $instance, %params) = @_;
433 if ($instance->can('meta')) {
434 ($instance->meta->isa('Class::MOP::Class'))
435 || confess 'Cannot rebless instance if ->meta is not an instance of Class::MOP::Class';
436 $old_metaclass = $instance->meta;
439 $old_metaclass = $self->initialize(blessed($instance));
442 $old_metaclass->rebless_instance_away($instance, $self, %params);
444 my $meta_instance = $self->get_meta_instance();
446 $self->name->isa($old_metaclass->name)
447 || confess "You may rebless only into a subclass of (". $old_metaclass->name ."), of which (". $self->name .") isn't.";
450 # we use $_[1] here because of t/306_rebless_overload.t regressions on 5.8.8
451 $meta_instance->rebless_instance_structure($_[1], $self);
453 foreach my $attr ( $self->compute_all_applicable_attributes ) {
454 if ( $attr->has_value($instance) ) {
455 if ( defined( my $init_arg = $attr->init_arg ) ) {
456 $params{$init_arg} = $attr->get_value($instance)
457 unless exists $params{$init_arg};
460 $attr->set_value($instance, $attr->get_value($instance));
465 foreach my $attr ($self->compute_all_applicable_attributes) {
466 $attr->initialize_instance_slot($meta_instance, $instance, \%params);
472 sub rebless_instance_away {
473 # this intentionally does nothing, it is just a hook
480 my $var_spec = { sigil => '@', type => 'ARRAY', name => 'ISA' };
483 @{$self->get_package_symbol($var_spec)} = @supers;
486 # on 5.8 and below, we need to call
487 # a method to get Perl to detect
488 # a cycle in the class hierarchy
489 my $class = $self->name;
493 # we need to check the metaclass
494 # compatibility here so that we can
495 # be sure that the superclass is
496 # not potentially creating an issues
497 # we don't know about
499 $self->_check_metaclass_compatibility();
500 $self->update_meta_instance_dependencies();
502 @{$self->get_package_symbol($var_spec)};
508 my $super_class = $self->name;
510 if ( Class::MOP::HAVE_ISAREV() ) {
511 return @{ $super_class->mro::get_isarev() };
515 my $find_derived_classes;
516 $find_derived_classes = sub {
517 my ($outer_class) = @_;
519 my $symbol_table_hashref = do { no strict 'refs'; \%{"${outer_class}::"} };
522 for my $symbol ( keys %$symbol_table_hashref ) {
523 next SYMBOL if $symbol !~ /\A (\w+):: \z/x;
524 my $inner_class = $1;
526 next SYMBOL if $inner_class eq 'SUPER'; # skip '*::SUPER'
530 ? "${outer_class}::$inner_class"
533 if ( $class->isa($super_class) and $class ne $super_class ) {
534 push @derived_classes, $class;
537 next SYMBOL if $class eq 'main'; # skip 'main::*'
539 $find_derived_classes->($class);
543 my $root_class = q{};
544 $find_derived_classes->($root_class);
546 undef $find_derived_classes;
548 @derived_classes = sort { $a->isa($b) ? 1 : $b->isa($a) ? -1 : 0 } @derived_classes;
550 return @derived_classes;
556 return @{ mro::get_linear_isa( (shift)->name ) };
559 sub class_precedence_list {
561 my $name = $self->name;
563 unless (Class::MOP::IS_RUNNING_ON_5_10()) {
565 # We need to check for circular inheritance here
566 # if we are are not on 5.10, cause 5.8 detects it
567 # late. This will do nothing if all is well, and
568 # blow up otherwise. Yes, it's an ugly hack, better
569 # suggestions are welcome.
571 ($name || return)->isa('This is a test for circular inheritance')
574 # if our mro is c3, we can
575 # just grab the linear_isa
576 if (mro::get_mro($name) eq 'c3') {
577 return @{ mro::get_linear_isa($name) }
581 # we can't grab the linear_isa for dfs
582 # since it has all the duplicates
587 $self->initialize($_)->class_precedence_list()
588 } $self->superclasses()
595 sub wrap_method_body {
596 my ( $self, %args ) = @_;
598 ('CODE' eq ref $args{body})
599 || confess "Your code block must be a CODE reference";
601 $self->method_metaclass->wrap(
602 package_name => $self->name,
608 my ($self, $method_name, $method) = @_;
609 (defined $method_name && $method_name)
610 || confess "You must define a method name";
613 if (blessed($method)) {
614 $body = $method->body;
615 if ($method->package_name ne $self->name) {
616 $method = $method->clone(
617 package_name => $self->name,
619 ) if $method->can('clone');
624 $method = $self->wrap_method_body( body => $body, name => $method_name );
627 $method->attach_to_class($self);
629 # This used to call get_method_map, which meant we would build all
630 # the method objects for the class just because we added one
631 # method. This is hackier, but quicker too.
632 $self->{methods}{$method_name} = $method;
634 my $full_method_name = ($self->name . '::' . $method_name);
635 $self->add_package_symbol(
636 { sigil => '&', type => 'CODE', name => $method_name },
637 Class::MOP::subname($full_method_name => $body)
642 my $fetch_and_prepare_method = sub {
643 my ($self, $method_name) = @_;
644 my $wrapped_metaclass = $self->wrapped_method_metaclass;
646 my $method = $self->get_method($method_name);
647 # if we dont have local ...
649 # try to find the next method
650 $method = $self->find_next_method_by_name($method_name);
651 # die if it does not exist
653 || confess "The method '$method_name' was not found in the inheritance hierarchy for " . $self->name;
654 # and now make sure to wrap it
655 # even if it is already wrapped
656 # because we need a new sub ref
657 $method = $wrapped_metaclass->wrap($method);
660 # now make sure we wrap it properly
661 $method = $wrapped_metaclass->wrap($method)
662 unless $method->isa($wrapped_metaclass);
664 $self->add_method($method_name => $method);
668 sub add_before_method_modifier {
669 my ($self, $method_name, $method_modifier) = @_;
670 (defined $method_name && $method_name)
671 || confess "You must pass in a method name";
672 my $method = $fetch_and_prepare_method->($self, $method_name);
673 $method->add_before_modifier(
674 Class::MOP::subname(':before' => $method_modifier)
678 sub add_after_method_modifier {
679 my ($self, $method_name, $method_modifier) = @_;
680 (defined $method_name && $method_name)
681 || confess "You must pass in a method name";
682 my $method = $fetch_and_prepare_method->($self, $method_name);
683 $method->add_after_modifier(
684 Class::MOP::subname(':after' => $method_modifier)
688 sub add_around_method_modifier {
689 my ($self, $method_name, $method_modifier) = @_;
690 (defined $method_name && $method_name)
691 || confess "You must pass in a method name";
692 my $method = $fetch_and_prepare_method->($self, $method_name);
693 $method->add_around_modifier(
694 Class::MOP::subname(':around' => $method_modifier)
699 # the methods above used to be named like this:
700 # ${pkg}::${method}:(before|after|around)
701 # but this proved problematic when using one modifier
702 # to wrap multiple methods (something which is likely
703 # to happen pretty regularly IMO). So instead of naming
704 # it like this, I have chosen to just name them purely
705 # with their modifier names, like so:
706 # :(before|after|around)
707 # The fact is that in a stack trace, it will be fairly
708 # evident from the context what method they are attached
709 # to, and so don't need the fully qualified name.
713 warn "The alias_method method is deprecated. Use add_method instead.\n";
719 my ($self, $method_name) = @_;
720 (defined $method_name && $method_name)
721 || confess "You must define a method name";
723 exists $self->{methods}{$method_name} || exists $self->get_method_map->{$method_name};
727 my ($self, $method_name) = @_;
728 (defined $method_name && $method_name)
729 || confess "You must define a method name";
731 return $self->{methods}{$method_name} || $self->get_method_map->{$method_name};
735 my ($self, $method_name) = @_;
736 (defined $method_name && $method_name)
737 || confess "You must define a method name";
739 my $removed_method = delete $self->get_method_map->{$method_name};
741 $self->remove_package_symbol(
742 { sigil => '&', type => 'CODE', name => $method_name }
745 $removed_method->detach_from_class if $removed_method;
747 $self->update_package_cache_flag; # still valid, since we just removed the method from the map
749 return $removed_method;
752 sub get_method_list {
754 keys %{$self->get_method_map};
757 sub find_method_by_name {
758 my ($self, $method_name) = @_;
759 (defined $method_name && $method_name)
760 || confess "You must define a method name to find";
761 foreach my $class ($self->linearized_isa) {
762 # fetch the meta-class ...
763 my $meta = $self->initialize($class);
764 return $meta->get_method($method_name)
765 if $meta->has_method($method_name);
770 sub get_all_methods {
772 my %methods = map { %{ $self->initialize($_)->get_method_map } } reverse $self->linearized_isa;
773 return values %methods;
776 sub compute_all_applicable_methods {
777 warn 'The compute_all_applicable_methods method is deprecated.'
778 . " Use get_all_methods instead.\n";
783 class => $_->package_name,
784 code => $_, # sigh, overloading
786 } shift->get_all_methods(@_);
789 sub get_all_method_names {
792 grep { $uniq{$_}++ == 0 } map { $_->name } $self->get_all_methods;
795 sub find_all_methods_by_name {
796 my ($self, $method_name) = @_;
797 (defined $method_name && $method_name)
798 || confess "You must define a method name to find";
800 foreach my $class ($self->linearized_isa) {
801 # fetch the meta-class ...
802 my $meta = $self->initialize($class);
804 name => $method_name,
806 code => $meta->get_method($method_name)
807 } if $meta->has_method($method_name);
812 sub find_next_method_by_name {
813 my ($self, $method_name) = @_;
814 (defined $method_name && $method_name)
815 || confess "You must define a method name to find";
816 my @cpl = $self->linearized_isa;
817 shift @cpl; # discard ourselves
818 foreach my $class (@cpl) {
819 # fetch the meta-class ...
820 my $meta = $self->initialize($class);
821 return $meta->get_method($method_name)
822 if $meta->has_method($method_name);
831 # either we have an attribute object already
832 # or we need to create one from the args provided
833 my $attribute = blessed($_[0]) ? $_[0] : $self->attribute_metaclass->new(@_);
834 # make sure it is derived from the correct type though
835 ($attribute->isa('Class::MOP::Attribute'))
836 || confess "Your attribute must be an instance of Class::MOP::Attribute (or a subclass)";
838 # first we attach our new attribute
839 # because it might need certain information
840 # about the class which it is attached to
841 $attribute->attach_to_class($self);
843 # then we remove attributes of a conflicting
844 # name here so that we can properly detach
845 # the old attr object, and remove any
846 # accessors it would have generated
847 if ( $self->has_attribute($attribute->name) ) {
848 $self->remove_attribute($attribute->name);
850 $self->invalidate_meta_instances();
853 # then onto installing the new accessors
854 $self->get_attribute_map->{$attribute->name} = $attribute;
856 # invalidate package flag here
857 my $e = do { local $@; eval { $attribute->install_accessors() }; $@ };
859 $self->remove_attribute($attribute->name);
866 sub update_meta_instance_dependencies {
869 if ( $self->{meta_instance_dependencies} ) {
870 return $self->add_meta_instance_dependencies;
874 sub add_meta_instance_dependencies {
877 $self->remove_meta_instance_dependencies;
879 my @attrs = $self->compute_all_applicable_attributes();
882 my @classes = grep { not $seen{$_->name}++ } map { $_->associated_class } @attrs;
884 foreach my $class ( @classes ) {
885 $class->add_dependent_meta_instance($self);
888 $self->{meta_instance_dependencies} = \@classes;
891 sub remove_meta_instance_dependencies {
894 if ( my $classes = delete $self->{meta_instance_dependencies} ) {
895 foreach my $class ( @$classes ) {
896 $class->remove_dependent_meta_instance($self);
906 sub add_dependent_meta_instance {
907 my ( $self, $metaclass ) = @_;
908 push @{ $self->{dependent_meta_instances} }, $metaclass;
911 sub remove_dependent_meta_instance {
912 my ( $self, $metaclass ) = @_;
913 my $name = $metaclass->name;
914 @$_ = grep { $_->name ne $name } @$_ for $self->{dependent_meta_instances};
917 sub invalidate_meta_instances {
919 $_->invalidate_meta_instance() for $self, @{ $self->{dependent_meta_instances} };
922 sub invalidate_meta_instance {
924 undef $self->{_meta_instance};
928 my ($self, $attribute_name) = @_;
929 (defined $attribute_name && $attribute_name)
930 || confess "You must define an attribute name";
931 exists $self->get_attribute_map->{$attribute_name};
935 my ($self, $attribute_name) = @_;
936 (defined $attribute_name && $attribute_name)
937 || confess "You must define an attribute name";
938 return $self->get_attribute_map->{$attribute_name}
940 # this will return undef anyway, so no need ...
941 # if $self->has_attribute($attribute_name);
945 sub remove_attribute {
946 my ($self, $attribute_name) = @_;
947 (defined $attribute_name && $attribute_name)
948 || confess "You must define an attribute name";
949 my $removed_attribute = $self->get_attribute_map->{$attribute_name};
950 return unless defined $removed_attribute;
951 delete $self->get_attribute_map->{$attribute_name};
952 $self->invalidate_meta_instances();
953 $removed_attribute->remove_accessors();
954 $removed_attribute->detach_from_class();
955 return $removed_attribute;
958 sub get_attribute_list {
960 keys %{$self->get_attribute_map};
963 sub get_all_attributes {
964 shift->compute_all_applicable_attributes(@_);
967 sub compute_all_applicable_attributes {
969 my %attrs = map { %{ $self->initialize($_)->get_attribute_map } } reverse $self->linearized_isa;
970 return values %attrs;
973 sub find_attribute_by_name {
974 my ($self, $attr_name) = @_;
975 foreach my $class ($self->linearized_isa) {
976 # fetch the meta-class ...
977 my $meta = $self->initialize($class);
978 return $meta->get_attribute($attr_name)
979 if $meta->has_attribute($attr_name);
984 # check if we can reinitialize
988 # if any local attr is defined
989 return if $self->get_attribute_list;
991 # or any non-declared methods
992 if ( my @methods = values %{ $self->get_method_map } ) {
993 my $metaclass = $self->method_metaclass;
994 foreach my $method ( @methods ) {
995 return if $method->isa("Class::MOP::Method::Generated");
996 # FIXME do we need to enforce this too? return unless $method->isa($metaclass);
1005 sub is_mutable { 1 }
1006 sub is_immutable { 0 }
1008 sub immutable_transformer { $_[0]->{immutable_transformer} }
1009 sub _set_immutable_transformer { $_[0]->{immutable_transformer} = $_[1] }
1011 sub make_immutable {
1014 return if $self->is_immutable;
1016 my $transformer = $self->immutable_transformer
1017 || $self->_make_immutable_transformer(@_);
1019 $self->_set_immutable_transformer($transformer);
1021 $transformer->make_metaclass_immutable;
1025 my %Default_Immutable_Options = (
1026 read_only => [qw/superclasses/],
1034 remove_package_symbol
1038 class_precedence_list => 'ARRAY',
1039 # FIXME perl 5.10 memoizes this on its own, no need?
1040 linearized_isa => 'ARRAY',
1041 get_all_methods => 'ARRAY',
1042 get_all_method_names => 'ARRAY',
1043 compute_all_applicable_attributes => 'ARRAY',
1044 get_meta_instance => 'SCALAR',
1045 get_method_map => 'SCALAR',
1049 # this is ugly, but so are typeglobs,
1050 # so whattayahgonnadoboutit
1053 add_package_symbol => sub {
1054 my $original = shift;
1055 confess "Cannot add package symbols to an immutable metaclass"
1056 unless ( caller(2) )[3] eq
1057 'Class::MOP::Package::get_package_symbol';
1059 # This is a workaround for a bug in 5.8.1 which thinks that
1060 # goto $original->body
1061 # is trying to go to a label
1062 my $body = $original->body;
1068 sub _default_immutable_transformer_options {
1069 return %Default_Immutable_Options;
1073 sub _make_immutable_transformer {
1076 Class::MOP::Immutable->new(
1078 $self->_default_immutable_transformer_options,
1086 return if $self->is_mutable;
1088 $self->immutable_transformer->make_metaclass_mutable;
1099 Class::MOP::Class - Class Meta Object
1103 # assuming that class Foo
1104 # has been defined, you can
1106 # use this for introspection ...
1108 # add a method to Foo ...
1109 Foo->meta->add_method( 'bar' => sub {...} )
1111 # get a list of all the classes searched
1112 # the method dispatcher in the correct order
1113 Foo->meta->class_precedence_list()
1115 # remove a method from Foo
1116 Foo->meta->remove_method('bar');
1118 # or use this to actually create classes ...
1120 Class::MOP::Class->create(
1123 superclasses => ['Foo'],
1125 Class::MOP:: : Attribute->new('$bar'),
1126 Class::MOP:: : Attribute->new('$baz'),
1129 calculate_bar => sub {...},
1130 construct_baz => sub {...}
1137 The Class Protocol is the largest and most complex part of the
1138 Class::MOP meta-object protocol. It controls the introspection and
1139 manipulation of Perl 5 classes, and it can create them as well. The
1140 best way to understand what this module can do, is to read the
1141 documentation for each of its methods.
1145 C<Class::MOP::Class> is a subclass of L<Class::MOP::Module>.
1149 =head2 Class construction
1151 These methods all create new C<Class::MOP::Class> objects. These
1152 objects can represent existing classes, or they can be used to create
1153 new classes from scratch.
1155 The metaclass object for a given class is a singleton. If you attempt
1156 to create a metaclass for the same class twice, you will just get the
1161 =item B<< Class::MOP::Class->create($package_name, %options) >>
1163 This method creates a new C<Class::MOP::Class> object with the given
1164 package name. It accepts a number of options.
1170 An optional version number for the newly created package.
1174 An optional authority for the newly created package.
1176 =item * superclasses
1178 An optional array reference of superclass names.
1182 An optional hash reference of methods for the class. The keys of the
1183 hash reference are method names, and values are subroutine references.
1187 An optional array reference of attributes.
1189 An attribute can be passed as an existing L<Class::MOP::Attribute>
1190 object, I<or> or as a hash reference of options which will be passed
1191 to the attribute metaclass's constructor.
1195 =item B<< Class::MOP::Class->create_anon_class(%options) >>
1197 This method works just like C<< Class::MOP::Class->create >> but it
1198 creates an "anonymous" class. In fact, the class does have a name, but
1199 that name is a unique name generated internally by this module.
1201 It accepts the same C<superclasses>, C<methods>, and C<attributes>
1202 parameters that C<create> accepts.
1204 Anonymous classes are destroyed once the metaclass they are attached
1205 to goes out of scope, and will be removed from Perl's internal symbol
1208 All instances of an anonymous class keep a special reference to the
1209 metaclass object, which prevents the metaclass from going out of scope
1210 while any instances exist.
1212 This only works if the instance if based on a hash reference, however.
1214 =item B<< Class::MOP::Class->initialize($package_name, %options) >>
1216 This method will initialize a C<Class::MOP::Class> object for the
1217 named package. Unlike C<create>, this method I<will not> create a new
1220 The purpose of this method is to retrieve a C<Class::MOP::Class>
1221 object for introspecting an existing class.
1223 If an existing C<Class::MOP::Class> object exists for the named
1224 package, it will be returned, and any options provided will be
1227 If the object does not yet exist, it will be created.
1229 The valid options that can be passed to this method are
1230 C<attribute_metaclass>, C<method_metaclass>,
1231 C<wrapped_method_metaclass>, and C<instance_metaclass>. These are all
1232 optional, and default to the appropriate class in the C<Class::MOP>
1237 =head2 Object instance construction and cloning
1239 These methods are all related to creating and/or cloning object
1244 =item B<< $metaclass->clone_object($instance, %params) >>
1246 This method clones an existing object instance. Any parameters you
1247 provide are will override existing attribute values in the object.
1249 This is a convenience method for cloning an object instance, then
1250 blessing it into the appropriate package.
1252 You could implement a clone method in your class, using this method:
1255 my ($self, %params) = @_;
1256 $self->meta->clone_object($self, %params);
1259 =item B<< $metaclass->rebless_instance($instance, %params) >>
1261 This method changes the class of C<$instance> to the metaclass's class.
1263 You can only rebless an instance into a subclass of its current
1264 class. If you pass any additional parameters, these will be treated
1265 like constructor parameters and used to initialize the object's
1266 attributes. Any existing attributes that are already set will be
1269 Before reblessing the instance, this method will call
1270 C<rebless_instance_away> on the instance's current metaclass. This method
1271 will be passed the instance, the new metaclass, and any parameters
1272 specified to C<rebless_instance>. By default, C<rebless_instance_away>
1273 does nothing; it is merely a hook.
1275 =item B<< $metaclass->new_object(%params) >>
1277 This method is used to create a new object of the metaclass's
1278 class. Any parameters you provide are used to initialize the
1279 instance's attributes.
1281 =item B<< $metaclass->instance_metaclass >>
1283 Returns the class name of the instance metaclass, see
1284 L<Class::MOP::Instance> for more information on the instance
1287 =item B<< $metaclass->get_meta_instance >>
1289 Returns an instance of the C<instance_metaclass> to be used in the
1290 construction of a new instance of the class.
1294 =head2 Informational predicates
1296 These are a few predicate methods for asking information about the
1301 =item B<< $metaclass->is_anon_class >>
1303 This returns true if the class was created by calling C<<
1304 Class::MOP::Class->create_anon_class >>.
1306 =item B<< $metaclass->is_mutable >>
1308 This returns true if the class is still mutable.
1310 =item B<< $metaclass->is_immutable >>
1312 This returns true if the class has been made immutable.
1314 =item B<< $metaclass->is_pristine >>
1316 A class is I<not> pristine if it has non-inherited attributes or if it
1317 has any generated methods.
1321 =head2 Inheritance Relationships
1325 =item B<< $metaclass->superclasses(@superclasses) >>
1327 This is a read-write accessor which represents the superclass
1328 relationships of the metaclass's class.
1330 This is basically sugar around getting and setting C<@ISA>.
1332 =item B<< $metaclass->class_precedence_list >>
1334 This returns a list of all of the class's ancestor classes. The
1335 classes are returned in method dispatch order.
1337 =item B<< $metaclass->linearized_isa >>
1339 This returns a list based on C<class_precedence_list> but with all
1342 =item B<< $metaclass->subclasses >>
1344 This returns a list of subclasses for this class.
1348 =head2 Method introspection and creation
1350 These methods allow you to introspect a class's methods, as well as
1351 add, remove, or change methods.
1353 Determining what is truly a method in a Perl 5 class requires some
1354 heuristics (aka guessing).
1356 Methods defined outside the package with a fully qualified name (C<sub
1357 Package::name { ... }>) will be included. Similarly, methods named
1358 with a fully qualified name using L<Sub::Name> are also included.
1360 However, we attempt to ignore imported functions.
1362 Ultimately, we are using heuristics to determine what truly is a
1363 method in a class, and these heuristics may get the wrong answer in
1364 some edge cases. However, for most "normal" cases the heuristics work
1369 =item B<< $metaclass->get_method($method_name) >>
1371 This will return a L<Class::MOP::Method> for the specified
1372 C<$method_name>. If the class does not have the specified method, it
1375 =item B<< $metaclass->has_method($method_name) >>
1377 Returns a boolean indicating whether or not the class defines the
1378 named method. It does not include methods inherited from parent
1381 =item B<< $metaclass->get_method_map >>
1383 Returns a hash reference representing the methods defined in this
1384 class. The keys are method names and the values are
1385 L<Class::MOP::Method> objects.
1387 =item B<< $metaclass->get_method_list >>
1389 This will return a list of method I<names> for all methods defined in
1392 =item B<< $metaclass->get_all_methods >>
1394 This will traverse the inheritance hierarchy and return a list of all
1395 the L<Class::MOP::Method> objects for this class and its parents.
1397 =item B<< $metaclass->find_method_by_name($method_name) >>
1399 This will return a L<Class::MOP::Method> for the specified
1400 C<$method_name>. If the class does not have the specified method, it
1403 Unlike C<get_method>, this method I<will> look for the named method in
1406 =item B<< $metaclass->get_all_method_names >>
1408 This will return a list of method I<names> for all of this class's
1409 methods, including inherited methods.
1411 =item B<< $metaclass->find_all_methods_by_name($method_name) >>
1413 This method looks for the named method in the class and all of its
1414 parents. It returns every matching method it finds in the inheritance
1415 tree, so it returns a list of methods.
1417 Each method is returned as a hash reference with three keys. The keys
1418 are C<name>, C<class>, and C<code>. The C<code> key has a
1419 L<Class::MOP::Method> object as its value.
1421 The list of methods is distinct.
1423 =item B<< $metaclass->find_next_method_by_name($method_name) >>
1425 This method returns the first method in any superclass matching the
1426 given name. It is effectively the method that C<SUPER::$method_name>
1429 =item B<< $metaclass->add_method($method_name, $method) >>
1431 This method takes a method name and a subroutine reference, and adds
1432 the method to the class.
1434 The subroutine reference can be a L<Class::MOP::Method>, and you are
1435 strongly encouraged to pass a meta method object instead of a code
1436 reference. If you do so, that object gets stored as part of the
1437 class's method map directly. If not, the meta information will have to
1438 be recreated later, and may be incorrect.
1440 If you provide a method object, this method will clone that object if
1441 the object's package name does not match the class name. This lets us
1442 track the original source of any methods added from other classes
1443 (notably Moose roles).
1445 =item B<< $metaclass->remove_method($method_name) >>
1447 Remove the named method from the class. This method returns the
1448 L<Class::MOP::Method> object for the method.
1450 =item B<< $metaclass->method_metaclass >>
1452 Returns the class name of the method metaclass, see
1453 L<Class::MOP::Method> for more information on the method metaclass.
1455 =item B<< $metaclass->wrapped_method_metaclass >>
1457 Returns the class name of the wrapped method metaclass, see
1458 L<Class::MOP::Method::Wrapped> for more information on the wrapped
1463 =head2 Attribute introspection and creation
1465 Because Perl 5 does not have a core concept of attributes in classes,
1466 we can only return information about attributes which have been added
1467 via this class's methods. We cannot discover information about
1468 attributes which are defined in terms of "regular" Perl 5 methods.
1472 =item B<< $metaclass->get_attribute($attribute_name) >>
1474 This will return a L<Class::MOP::Attribute> for the specified
1475 C<$attribute_name>. If the class does not have the specified
1476 attribute, it returns C<undef>
1478 =item B<< $metaclass->has_attribute($attribute_name) >>
1480 Returns a boolean indicating whether or not the class defines the
1481 named attribute. It does not include attributes inherited from parent
1484 =item B<< $metaclass->get_attribute_map >>
1486 Returns a hash reference representing the attributes defined in this
1487 class. The keys are attribute names and the values are
1488 L<Class::MOP::Attribute> objects.
1490 =item B<< $metaclass->get_attribute_list >>
1492 This will return a list of attributes I<names> for all attributes
1493 defined in this class.
1495 =item B<< $metaclass->get_all_attributes >>
1497 This will traverse the inheritance hierarchy and return a list of all
1498 the L<Class::MOP::Attribute> objects for this class and its parents.
1500 This method can also be called as C<compute_all_applicable_attributes>.
1502 =item B<< $metaclass->find_attribute_by_name($attribute_name) >>
1504 This will return a L<Class::MOP::Attribute> for the specified
1505 C<$attribute_name>. If the class does not have the specified
1506 attribute, it returns C<undef>
1508 Unlike C<get_attribute>, this attribute I<will> look for the named
1509 attribute in superclasses.
1511 =item B<< $metaclass->add_attribute(...) >>
1513 This method accepts either an existing L<Class::MOP::Attribute>
1514 object, or parameters suitable for passing to that class's C<new>
1517 The attribute provided will be added to the class.
1519 Any accessor methods defined by the attribute will be added to the
1520 class when the attribute is added.
1522 If an attribute of the same name already exists, the old attribute
1523 will be removed first.
1525 =item B<< $metaclass->remove_attribute($attribute_name) >>
1527 This will remove the named attribute from the class, and
1528 L<Class::MOP::Attribute> object.
1530 Removing an attribute also removes any accessor methods defined by the
1533 However, note that removing an attribute will only affect I<future>
1534 object instances created for this class, not existing instances.
1536 =item B<< $metaclass->attribute_metaclass >>
1538 Returns the class name of the attribute metaclass for this class. By
1539 default, this is L<Class::MOP::Attribute>. for more information on
1543 =head2 Class Immutability
1545 Making a class immutable "freezes" the class definition. You can no
1546 longer call methods which alter the class, such as adding or removing
1547 methods or attributes.
1549 Making a class immutable lets us optimize the class by inlining some
1550 methods, and also allows us to optimize some methods on the metaclass
1553 The immutabilization system in L<Moose> takes much greater advantage
1554 of the inlining features than Class::MOP itself does.
1558 =item B<< $metaclass->make_immutable(%options) >>
1560 This method will create an immutable transformer and uses it to make
1561 the class and its metaclass object immutable.
1563 Details of how immutabilization works are in L<Class::MOP::Immutable>
1566 =item B<< $metaclass->make_mutable >>
1568 Calling this method reverse the immutabilization transformation.
1570 =item B<< $metaclass->immutable_transformer >>
1572 If the class has been made immutable previously, this returns the
1573 L<Class::MOP::Immutable> object that was created to do the
1576 If the class was never made immutable, this method will die.
1580 =head2 Method Modifiers
1582 Method modifiers are hooks which allow a method to be wrapped with
1583 I<before>, I<after> and I<around> method modifiers. Every time a
1584 method is called, it's modifiers are also called.
1586 A class can modify its own methods, as well as methods defined in
1589 =head3 How method modifiers work?
1591 Method modifiers work by wrapping the original method and then
1592 replacing it in the class's symbol table. The wrappers will handle
1593 calling all the modifiers in the appropriate order and preserving the
1594 calling context for the original method.
1596 The return values of C<before> and C<after> modifiers are
1597 ignored. This is because their purpose is B<not> to filter the input
1598 and output of the primary method (this is done with an I<around>
1601 This may seem like an odd restriction to some, but doing this allows
1602 for simple code to be added at the beginning or end of a method call
1603 without altering the function of the wrapped method or placing any
1604 extra responsibility on the code of the modifier.
1606 Of course if you have more complex needs, you can use the C<around>
1607 modifier which allows you to change both the parameters passed to the
1608 wrapped method, as well as its return value.
1610 Before and around modifiers are called in last-defined-first-called
1611 order, while after modifiers are called in first-defined-first-called
1612 order. So the call tree might looks something like this:
1624 =head3 What is the performance impact?
1626 Of course there is a performance cost associated with method
1627 modifiers, but we have made every effort to make that cost directly
1628 proportional to the number of modifier features you utilize.
1630 The wrapping method does it's best to B<only> do as much work as it
1631 absolutely needs to. In order to do this we have moved some of the
1632 performance costs to set-up time, where they are easier to amortize.
1634 All this said, our benchmarks have indicated the following:
1636 simple wrapper with no modifiers 100% slower
1637 simple wrapper with simple before modifier 400% slower
1638 simple wrapper with simple after modifier 450% slower
1639 simple wrapper with simple around modifier 500-550% slower
1640 simple wrapper with all 3 modifiers 1100% slower
1642 These numbers may seem daunting, but you must remember, every feature
1643 comes with some cost. To put things in perspective, just doing a
1644 simple C<AUTOLOAD> which does nothing but extract the name of the
1645 method called and return it costs about 400% over a normal method
1650 =item B<< $metaclass->add_before_method_modifier($method_name, $code) >>
1652 This wraps the specified method with the supplied subroutine
1653 reference. The modifier will be called as a method itself, and will
1654 receive the same arguments as are passed to the method.
1656 When the modifier exits, the wrapped method will be called.
1658 The return value of the modifier will be ignored.
1660 =item B<< $metaclass->add_after_method_modifier($method_name, $code) >>
1662 This wraps the specified method with the supplied subroutine
1663 reference. The modifier will be called as a method itself, and will
1664 receive the same arguments as are passed to the method.
1666 When the wrapped methods exits, the modifier will be called.
1668 The return value of the modifier will be ignored.
1670 =item B<< $metaclass->add_around_method_modifier($method_name, $code) >>
1672 This wraps the specified method with the supplied subroutine
1675 The first argument passed to the modifier will be a subroutine
1676 reference to the wrapped method. The second argument is the object,
1677 and after that come any arguments passed when the method is called.
1679 The around modifier can choose to call the original method, as well as
1680 what arguments to pass if it does so.
1682 The return value of the modifier is what will be seen by the caller.
1686 =head2 Introspection
1690 =item B<< Class::MOP::Class->meta >>
1692 This will return a L<Class::MOP::Class> instance for this class.
1694 It should also be noted that L<Class::MOP> will actually bootstrap
1695 this module by installing a number of attribute meta-objects into its
1702 Stevan Little E<lt>stevan@iinteractive.comE<gt>
1704 =head1 COPYRIGHT AND LICENSE
1706 Copyright 2006-2009 by Infinity Interactive, Inc.
1708 L<http://www.iinteractive.com>
1710 This library is free software; you can redistribute it and/or modify
1711 it under the same terms as Perl itself.