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 {
345 warn 'The construct_instance method has been made private.'
346 . " The public version is deprecated and will be removed in a future release.\n";
347 shift->_construct_instance;
350 sub _construct_instance {
352 my $params = @_ == 1 ? $_[0] : {@_};
353 my $meta_instance = $class->get_meta_instance();
354 my $instance = $meta_instance->create_instance();
355 foreach my $attr ($class->compute_all_applicable_attributes()) {
356 $attr->initialize_instance_slot($meta_instance, $instance, $params);
359 # this will only work for a HASH instance type
360 if ($class->is_anon_class) {
361 (Scalar::Util::reftype($instance) eq 'HASH')
362 || confess "Currently only HASH based instances are supported with instance of anon-classes";
364 # At some point we should make this official
365 # as a reserved slot name, but right now I am
366 # going to keep it here.
367 # my $RESERVED_MOP_SLOT = '__MOP__';
368 $instance->{'__MOP__'} = $class;
374 sub get_meta_instance {
376 $self->{'_meta_instance'} ||= $self->_create_meta_instance();
379 sub create_meta_instance {
380 warn 'The create_meta_instance method has been made private.'
381 . " The public version is deprecated and will be removed in a future release.\n";
382 shift->_create_meta_instance;
385 sub _create_meta_instance {
388 my $instance = $self->instance_metaclass->new(
389 associated_metaclass => $self,
390 attributes => [ $self->compute_all_applicable_attributes() ],
393 $self->add_meta_instance_dependencies()
394 if $instance->is_dependent_on_superclasses();
401 my $instance = shift;
402 (blessed($instance) && $instance->isa($class->name))
403 || confess "You must pass an instance of the metaclass (" . (ref $class ? $class->name : $class) . "), not ($instance)";
406 # we need to protect the integrity of the
407 # Class::MOP::Class singletons here, they
408 # should not be cloned.
409 return $instance if $instance->isa('Class::MOP::Class');
410 $class->_clone_instance($instance, @_);
414 warn 'The clone_instance method has been made private.'
415 . " The public version is deprecated and will be removed in a future release.\n";
416 shift->_clone_instance;
419 sub _clone_instance {
420 my ($class, $instance, %params) = @_;
422 || confess "You can only clone instances, ($instance) is not a blessed instance";
423 my $meta_instance = $class->get_meta_instance();
424 my $clone = $meta_instance->clone_instance($instance);
425 foreach my $attr ($class->compute_all_applicable_attributes()) {
426 if ( defined( my $init_arg = $attr->init_arg ) ) {
427 if (exists $params{$init_arg}) {
428 $attr->set_value($clone, $params{$init_arg});
435 sub rebless_instance {
436 my ($self, $instance, %params) = @_;
439 if ($instance->can('meta')) {
440 ($instance->meta->isa('Class::MOP::Class'))
441 || confess 'Cannot rebless instance if ->meta is not an instance of Class::MOP::Class';
442 $old_metaclass = $instance->meta;
445 $old_metaclass = $self->initialize(blessed($instance));
448 $old_metaclass->rebless_instance_away($instance, $self, %params);
450 my $meta_instance = $self->get_meta_instance();
452 $self->name->isa($old_metaclass->name)
453 || confess "You may rebless only into a subclass of (". $old_metaclass->name ."), of which (". $self->name .") isn't.";
456 # we use $_[1] here because of t/306_rebless_overload.t regressions on 5.8.8
457 $meta_instance->rebless_instance_structure($_[1], $self);
459 foreach my $attr ( $self->compute_all_applicable_attributes ) {
460 if ( $attr->has_value($instance) ) {
461 if ( defined( my $init_arg = $attr->init_arg ) ) {
462 $params{$init_arg} = $attr->get_value($instance)
463 unless exists $params{$init_arg};
466 $attr->set_value($instance, $attr->get_value($instance));
471 foreach my $attr ($self->compute_all_applicable_attributes) {
472 $attr->initialize_instance_slot($meta_instance, $instance, \%params);
478 sub rebless_instance_away {
479 # this intentionally does nothing, it is just a hook
486 my $var_spec = { sigil => '@', type => 'ARRAY', name => 'ISA' };
489 @{$self->get_package_symbol($var_spec)} = @supers;
492 # on 5.8 and below, we need to call
493 # a method to get Perl to detect
494 # a cycle in the class hierarchy
495 my $class = $self->name;
499 # we need to check the metaclass
500 # compatibility here so that we can
501 # be sure that the superclass is
502 # not potentially creating an issues
503 # we don't know about
505 $self->_check_metaclass_compatibility();
506 $self->update_meta_instance_dependencies();
508 @{$self->get_package_symbol($var_spec)};
514 my $super_class = $self->name;
516 if ( Class::MOP::HAVE_ISAREV() ) {
517 return @{ $super_class->mro::get_isarev() };
521 my $find_derived_classes;
522 $find_derived_classes = sub {
523 my ($outer_class) = @_;
525 my $symbol_table_hashref = do { no strict 'refs'; \%{"${outer_class}::"} };
528 for my $symbol ( keys %$symbol_table_hashref ) {
529 next SYMBOL if $symbol !~ /\A (\w+):: \z/x;
530 my $inner_class = $1;
532 next SYMBOL if $inner_class eq 'SUPER'; # skip '*::SUPER'
536 ? "${outer_class}::$inner_class"
539 if ( $class->isa($super_class) and $class ne $super_class ) {
540 push @derived_classes, $class;
543 next SYMBOL if $class eq 'main'; # skip 'main::*'
545 $find_derived_classes->($class);
549 my $root_class = q{};
550 $find_derived_classes->($root_class);
552 undef $find_derived_classes;
554 @derived_classes = sort { $a->isa($b) ? 1 : $b->isa($a) ? -1 : 0 } @derived_classes;
556 return @derived_classes;
562 return @{ mro::get_linear_isa( (shift)->name ) };
565 sub class_precedence_list {
567 my $name = $self->name;
569 unless (Class::MOP::IS_RUNNING_ON_5_10()) {
571 # We need to check for circular inheritance here
572 # if we are are not on 5.10, cause 5.8 detects it
573 # late. This will do nothing if all is well, and
574 # blow up otherwise. Yes, it's an ugly hack, better
575 # suggestions are welcome.
577 ($name || return)->isa('This is a test for circular inheritance')
580 # if our mro is c3, we can
581 # just grab the linear_isa
582 if (mro::get_mro($name) eq 'c3') {
583 return @{ mro::get_linear_isa($name) }
587 # we can't grab the linear_isa for dfs
588 # since it has all the duplicates
593 $self->initialize($_)->class_precedence_list()
594 } $self->superclasses()
601 sub wrap_method_body {
602 my ( $self, %args ) = @_;
604 ('CODE' eq ref $args{body})
605 || confess "Your code block must be a CODE reference";
607 $self->method_metaclass->wrap(
608 package_name => $self->name,
614 my ($self, $method_name, $method) = @_;
615 (defined $method_name && $method_name)
616 || confess "You must define a method name";
619 if (blessed($method)) {
620 $body = $method->body;
621 if ($method->package_name ne $self->name) {
622 $method = $method->clone(
623 package_name => $self->name,
625 ) if $method->can('clone');
630 $method = $self->wrap_method_body( body => $body, name => $method_name );
633 $method->attach_to_class($self);
635 # This used to call get_method_map, which meant we would build all
636 # the method objects for the class just because we added one
637 # method. This is hackier, but quicker too.
638 $self->{methods}{$method_name} = $method;
640 my $full_method_name = ($self->name . '::' . $method_name);
641 $self->add_package_symbol(
642 { sigil => '&', type => 'CODE', name => $method_name },
643 Class::MOP::subname($full_method_name => $body)
648 my $fetch_and_prepare_method = sub {
649 my ($self, $method_name) = @_;
650 my $wrapped_metaclass = $self->wrapped_method_metaclass;
652 my $method = $self->get_method($method_name);
653 # if we dont have local ...
655 # try to find the next method
656 $method = $self->find_next_method_by_name($method_name);
657 # die if it does not exist
659 || confess "The method '$method_name' was not found in the inheritance hierarchy for " . $self->name;
660 # and now make sure to wrap it
661 # even if it is already wrapped
662 # because we need a new sub ref
663 $method = $wrapped_metaclass->wrap($method);
666 # now make sure we wrap it properly
667 $method = $wrapped_metaclass->wrap($method)
668 unless $method->isa($wrapped_metaclass);
670 $self->add_method($method_name => $method);
674 sub add_before_method_modifier {
675 my ($self, $method_name, $method_modifier) = @_;
676 (defined $method_name && $method_name)
677 || confess "You must pass in a method name";
678 my $method = $fetch_and_prepare_method->($self, $method_name);
679 $method->add_before_modifier(
680 Class::MOP::subname(':before' => $method_modifier)
684 sub add_after_method_modifier {
685 my ($self, $method_name, $method_modifier) = @_;
686 (defined $method_name && $method_name)
687 || confess "You must pass in a method name";
688 my $method = $fetch_and_prepare_method->($self, $method_name);
689 $method->add_after_modifier(
690 Class::MOP::subname(':after' => $method_modifier)
694 sub add_around_method_modifier {
695 my ($self, $method_name, $method_modifier) = @_;
696 (defined $method_name && $method_name)
697 || confess "You must pass in a method name";
698 my $method = $fetch_and_prepare_method->($self, $method_name);
699 $method->add_around_modifier(
700 Class::MOP::subname(':around' => $method_modifier)
705 # the methods above used to be named like this:
706 # ${pkg}::${method}:(before|after|around)
707 # but this proved problematic when using one modifier
708 # to wrap multiple methods (something which is likely
709 # to happen pretty regularly IMO). So instead of naming
710 # it like this, I have chosen to just name them purely
711 # with their modifier names, like so:
712 # :(before|after|around)
713 # The fact is that in a stack trace, it will be fairly
714 # evident from the context what method they are attached
715 # to, and so don't need the fully qualified name.
719 warn "The alias_method method is deprecated. Use add_method instead.\n";
725 my ($self, $method_name) = @_;
726 (defined $method_name && $method_name)
727 || confess "You must define a method name";
729 exists $self->{methods}{$method_name} || exists $self->get_method_map->{$method_name};
733 my ($self, $method_name) = @_;
734 (defined $method_name && $method_name)
735 || confess "You must define a method name";
737 return $self->{methods}{$method_name} || $self->get_method_map->{$method_name};
741 my ($self, $method_name) = @_;
742 (defined $method_name && $method_name)
743 || confess "You must define a method name";
745 my $removed_method = delete $self->get_method_map->{$method_name};
747 $self->remove_package_symbol(
748 { sigil => '&', type => 'CODE', name => $method_name }
751 $removed_method->detach_from_class if $removed_method;
753 $self->update_package_cache_flag; # still valid, since we just removed the method from the map
755 return $removed_method;
758 sub get_method_list {
760 keys %{$self->get_method_map};
763 sub find_method_by_name {
764 my ($self, $method_name) = @_;
765 (defined $method_name && $method_name)
766 || confess "You must define a method name to find";
767 foreach my $class ($self->linearized_isa) {
768 # fetch the meta-class ...
769 my $meta = $self->initialize($class);
770 return $meta->get_method($method_name)
771 if $meta->has_method($method_name);
776 sub get_all_methods {
778 my %methods = map { %{ $self->initialize($_)->get_method_map } } reverse $self->linearized_isa;
779 return values %methods;
782 sub compute_all_applicable_methods {
783 warn 'The compute_all_applicable_methods method is deprecated.'
784 . " Use get_all_methods instead.\n";
789 class => $_->package_name,
790 code => $_, # sigh, overloading
792 } shift->get_all_methods(@_);
795 sub get_all_method_names {
798 grep { $uniq{$_}++ == 0 } map { $_->name } $self->get_all_methods;
801 sub find_all_methods_by_name {
802 my ($self, $method_name) = @_;
803 (defined $method_name && $method_name)
804 || confess "You must define a method name to find";
806 foreach my $class ($self->linearized_isa) {
807 # fetch the meta-class ...
808 my $meta = $self->initialize($class);
810 name => $method_name,
812 code => $meta->get_method($method_name)
813 } if $meta->has_method($method_name);
818 sub find_next_method_by_name {
819 my ($self, $method_name) = @_;
820 (defined $method_name && $method_name)
821 || confess "You must define a method name to find";
822 my @cpl = $self->linearized_isa;
823 shift @cpl; # discard ourselves
824 foreach my $class (@cpl) {
825 # fetch the meta-class ...
826 my $meta = $self->initialize($class);
827 return $meta->get_method($method_name)
828 if $meta->has_method($method_name);
837 # either we have an attribute object already
838 # or we need to create one from the args provided
839 my $attribute = blessed($_[0]) ? $_[0] : $self->attribute_metaclass->new(@_);
840 # make sure it is derived from the correct type though
841 ($attribute->isa('Class::MOP::Attribute'))
842 || confess "Your attribute must be an instance of Class::MOP::Attribute (or a subclass)";
844 # first we attach our new attribute
845 # because it might need certain information
846 # about the class which it is attached to
847 $attribute->attach_to_class($self);
849 # then we remove attributes of a conflicting
850 # name here so that we can properly detach
851 # the old attr object, and remove any
852 # accessors it would have generated
853 if ( $self->has_attribute($attribute->name) ) {
854 $self->remove_attribute($attribute->name);
856 $self->invalidate_meta_instances();
859 # then onto installing the new accessors
860 $self->get_attribute_map->{$attribute->name} = $attribute;
862 # invalidate package flag here
863 my $e = do { local $@; eval { $attribute->install_accessors() }; $@ };
865 $self->remove_attribute($attribute->name);
872 sub update_meta_instance_dependencies {
875 if ( $self->{meta_instance_dependencies} ) {
876 return $self->add_meta_instance_dependencies;
880 sub add_meta_instance_dependencies {
883 $self->remove_meta_instance_dependencies;
885 my @attrs = $self->compute_all_applicable_attributes();
888 my @classes = grep { not $seen{$_->name}++ } map { $_->associated_class } @attrs;
890 foreach my $class ( @classes ) {
891 $class->add_dependent_meta_instance($self);
894 $self->{meta_instance_dependencies} = \@classes;
897 sub remove_meta_instance_dependencies {
900 if ( my $classes = delete $self->{meta_instance_dependencies} ) {
901 foreach my $class ( @$classes ) {
902 $class->remove_dependent_meta_instance($self);
912 sub add_dependent_meta_instance {
913 my ( $self, $metaclass ) = @_;
914 push @{ $self->{dependent_meta_instances} }, $metaclass;
917 sub remove_dependent_meta_instance {
918 my ( $self, $metaclass ) = @_;
919 my $name = $metaclass->name;
920 @$_ = grep { $_->name ne $name } @$_ for $self->{dependent_meta_instances};
923 sub invalidate_meta_instances {
925 $_->invalidate_meta_instance() for $self, @{ $self->{dependent_meta_instances} };
928 sub invalidate_meta_instance {
930 undef $self->{_meta_instance};
934 my ($self, $attribute_name) = @_;
935 (defined $attribute_name && $attribute_name)
936 || confess "You must define an attribute name";
937 exists $self->get_attribute_map->{$attribute_name};
941 my ($self, $attribute_name) = @_;
942 (defined $attribute_name && $attribute_name)
943 || confess "You must define an attribute name";
944 return $self->get_attribute_map->{$attribute_name}
946 # this will return undef anyway, so no need ...
947 # if $self->has_attribute($attribute_name);
951 sub remove_attribute {
952 my ($self, $attribute_name) = @_;
953 (defined $attribute_name && $attribute_name)
954 || confess "You must define an attribute name";
955 my $removed_attribute = $self->get_attribute_map->{$attribute_name};
956 return unless defined $removed_attribute;
957 delete $self->get_attribute_map->{$attribute_name};
958 $self->invalidate_meta_instances();
959 $removed_attribute->remove_accessors();
960 $removed_attribute->detach_from_class();
961 return $removed_attribute;
964 sub get_attribute_list {
966 keys %{$self->get_attribute_map};
969 sub get_all_attributes {
970 shift->compute_all_applicable_attributes(@_);
973 sub compute_all_applicable_attributes {
975 my %attrs = map { %{ $self->initialize($_)->get_attribute_map } } reverse $self->linearized_isa;
976 return values %attrs;
979 sub find_attribute_by_name {
980 my ($self, $attr_name) = @_;
981 foreach my $class ($self->linearized_isa) {
982 # fetch the meta-class ...
983 my $meta = $self->initialize($class);
984 return $meta->get_attribute($attr_name)
985 if $meta->has_attribute($attr_name);
990 # check if we can reinitialize
994 # if any local attr is defined
995 return if $self->get_attribute_list;
997 # or any non-declared methods
998 if ( my @methods = values %{ $self->get_method_map } ) {
999 my $metaclass = $self->method_metaclass;
1000 foreach my $method ( @methods ) {
1001 return if $method->isa("Class::MOP::Method::Generated");
1002 # FIXME do we need to enforce this too? return unless $method->isa($metaclass);
1011 sub is_mutable { 1 }
1012 sub is_immutable { 0 }
1014 sub immutable_transformer { $_[0]->{immutable_transformer} }
1015 sub _set_immutable_transformer { $_[0]->{immutable_transformer} = $_[1] }
1017 sub make_immutable {
1020 return if $self->is_immutable;
1022 my $transformer = $self->immutable_transformer
1023 || $self->_make_immutable_transformer(@_);
1025 $self->_set_immutable_transformer($transformer);
1027 $transformer->make_metaclass_immutable;
1031 my %Default_Immutable_Options = (
1032 read_only => [qw/superclasses/],
1040 remove_package_symbol
1044 class_precedence_list => 'ARRAY',
1045 # FIXME perl 5.10 memoizes this on its own, no need?
1046 linearized_isa => 'ARRAY',
1047 get_all_methods => 'ARRAY',
1048 get_all_method_names => 'ARRAY',
1049 compute_all_applicable_attributes => 'ARRAY',
1050 get_meta_instance => 'SCALAR',
1051 get_method_map => 'SCALAR',
1055 # this is ugly, but so are typeglobs,
1056 # so whattayahgonnadoboutit
1059 add_package_symbol => sub {
1060 my $original = shift;
1061 confess "Cannot add package symbols to an immutable metaclass"
1062 unless ( caller(2) )[3] eq
1063 'Class::MOP::Package::get_package_symbol';
1065 # This is a workaround for a bug in 5.8.1 which thinks that
1066 # goto $original->body
1067 # is trying to go to a label
1068 my $body = $original->body;
1074 sub _default_immutable_transformer_options {
1075 return %Default_Immutable_Options;
1079 sub _make_immutable_transformer {
1082 Class::MOP::Immutable->new(
1084 $self->_default_immutable_transformer_options,
1092 return if $self->is_mutable;
1094 $self->immutable_transformer->make_metaclass_mutable;
1105 Class::MOP::Class - Class Meta Object
1109 # assuming that class Foo
1110 # has been defined, you can
1112 # use this for introspection ...
1114 # add a method to Foo ...
1115 Foo->meta->add_method( 'bar' => sub {...} )
1117 # get a list of all the classes searched
1118 # the method dispatcher in the correct order
1119 Foo->meta->class_precedence_list()
1121 # remove a method from Foo
1122 Foo->meta->remove_method('bar');
1124 # or use this to actually create classes ...
1126 Class::MOP::Class->create(
1129 superclasses => ['Foo'],
1131 Class::MOP:: : Attribute->new('$bar'),
1132 Class::MOP:: : Attribute->new('$baz'),
1135 calculate_bar => sub {...},
1136 construct_baz => sub {...}
1143 The Class Protocol is the largest and most complex part of the
1144 Class::MOP meta-object protocol. It controls the introspection and
1145 manipulation of Perl 5 classes, and it can create them as well. The
1146 best way to understand what this module can do, is to read the
1147 documentation for each of its methods.
1151 C<Class::MOP::Class> is a subclass of L<Class::MOP::Module>.
1155 =head2 Class construction
1157 These methods all create new C<Class::MOP::Class> objects. These
1158 objects can represent existing classes, or they can be used to create
1159 new classes from scratch.
1161 The metaclass object for a given class is a singleton. If you attempt
1162 to create a metaclass for the same class twice, you will just get the
1167 =item B<< Class::MOP::Class->create($package_name, %options) >>
1169 This method creates a new C<Class::MOP::Class> object with the given
1170 package name. It accepts a number of options.
1176 An optional version number for the newly created package.
1180 An optional authority for the newly created package.
1182 =item * superclasses
1184 An optional array reference of superclass names.
1188 An optional hash reference of methods for the class. The keys of the
1189 hash reference are method names, and values are subroutine references.
1193 An optional array reference of attributes.
1195 An attribute can be passed as an existing L<Class::MOP::Attribute>
1196 object, I<or> or as a hash reference of options which will be passed
1197 to the attribute metaclass's constructor.
1201 =item B<< Class::MOP::Class->create_anon_class(%options) >>
1203 This method works just like C<< Class::MOP::Class->create >> but it
1204 creates an "anonymous" class. In fact, the class does have a name, but
1205 that name is a unique name generated internally by this module.
1207 It accepts the same C<superclasses>, C<methods>, and C<attributes>
1208 parameters that C<create> accepts.
1210 Anonymous classes are destroyed once the metaclass they are attached
1211 to goes out of scope, and will be removed from Perl's internal symbol
1214 All instances of an anonymous class keep a special reference to the
1215 metaclass object, which prevents the metaclass from going out of scope
1216 while any instances exist.
1218 This only works if the instance if based on a hash reference, however.
1220 =item B<< Class::MOP::Class->initialize($package_name, %options) >>
1222 This method will initialize a C<Class::MOP::Class> object for the
1223 named package. Unlike C<create>, this method I<will not> create a new
1226 The purpose of this method is to retrieve a C<Class::MOP::Class>
1227 object for introspecting an existing class.
1229 If an existing C<Class::MOP::Class> object exists for the named
1230 package, it will be returned, and any options provided will be
1233 If the object does not yet exist, it will be created.
1235 The valid options that can be passed to this method are
1236 C<attribute_metaclass>, C<method_metaclass>,
1237 C<wrapped_method_metaclass>, and C<instance_metaclass>. These are all
1238 optional, and default to the appropriate class in the C<Class::MOP>
1243 =head2 Object instance construction and cloning
1245 These methods are all related to creating and/or cloning object
1250 =item B<< $metaclass->clone_object($instance, %params) >>
1252 This method clones an existing object instance. Any parameters you
1253 provide are will override existing attribute values in the object.
1255 This is a convenience method for cloning an object instance, then
1256 blessing it into the appropriate package.
1258 You could implement a clone method in your class, using this method:
1261 my ($self, %params) = @_;
1262 $self->meta->clone_object($self, %params);
1265 =item B<< $metaclass->rebless_instance($instance, %params) >>
1267 This method changes the class of C<$instance> to the metaclass's class.
1269 You can only rebless an instance into a subclass of its current
1270 class. If you pass any additional parameters, these will be treated
1271 like constructor parameters and used to initialize the object's
1272 attributes. Any existing attributes that are already set will be
1275 Before reblessing the instance, this method will call
1276 C<rebless_instance_away> on the instance's current metaclass. This method
1277 will be passed the instance, the new metaclass, and any parameters
1278 specified to C<rebless_instance>. By default, C<rebless_instance_away>
1279 does nothing; it is merely a hook.
1281 =item B<< $metaclass->new_object(%params) >>
1283 This method is used to create a new object of the metaclass's
1284 class. Any parameters you provide are used to initialize the
1285 instance's attributes.
1287 =item B<< $metaclass->instance_metaclass >>
1289 Returns the class name of the instance metaclass, see
1290 L<Class::MOP::Instance> for more information on the instance
1293 =item B<< $metaclass->get_meta_instance >>
1295 Returns an instance of the C<instance_metaclass> to be used in the
1296 construction of a new instance of the class.
1300 =head2 Informational predicates
1302 These are a few predicate methods for asking information about the
1307 =item B<< $metaclass->is_anon_class >>
1309 This returns true if the class was created by calling C<<
1310 Class::MOP::Class->create_anon_class >>.
1312 =item B<< $metaclass->is_mutable >>
1314 This returns true if the class is still mutable.
1316 =item B<< $metaclass->is_immutable >>
1318 This returns true if the class has been made immutable.
1320 =item B<< $metaclass->is_pristine >>
1322 A class is I<not> pristine if it has non-inherited attributes or if it
1323 has any generated methods.
1327 =head2 Inheritance Relationships
1331 =item B<< $metaclass->superclasses(@superclasses) >>
1333 This is a read-write accessor which represents the superclass
1334 relationships of the metaclass's class.
1336 This is basically sugar around getting and setting C<@ISA>.
1338 =item B<< $metaclass->class_precedence_list >>
1340 This returns a list of all of the class's ancestor classes. The
1341 classes are returned in method dispatch order.
1343 =item B<< $metaclass->linearized_isa >>
1345 This returns a list based on C<class_precedence_list> but with all
1348 =item B<< $metaclass->subclasses >>
1350 This returns a list of subclasses for this class.
1354 =head2 Method introspection and creation
1356 These methods allow you to introspect a class's methods, as well as
1357 add, remove, or change methods.
1359 Determining what is truly a method in a Perl 5 class requires some
1360 heuristics (aka guessing).
1362 Methods defined outside the package with a fully qualified name (C<sub
1363 Package::name { ... }>) will be included. Similarly, methods named
1364 with a fully qualified name using L<Sub::Name> are also included.
1366 However, we attempt to ignore imported functions.
1368 Ultimately, we are using heuristics to determine what truly is a
1369 method in a class, and these heuristics may get the wrong answer in
1370 some edge cases. However, for most "normal" cases the heuristics work
1375 =item B<< $metaclass->get_method($method_name) >>
1377 This will return a L<Class::MOP::Method> for the specified
1378 C<$method_name>. If the class does not have the specified method, it
1381 =item B<< $metaclass->has_method($method_name) >>
1383 Returns a boolean indicating whether or not the class defines the
1384 named method. It does not include methods inherited from parent
1387 =item B<< $metaclass->get_method_map >>
1389 Returns a hash reference representing the methods defined in this
1390 class. The keys are method names and the values are
1391 L<Class::MOP::Method> objects.
1393 =item B<< $metaclass->get_method_list >>
1395 This will return a list of method I<names> for all methods defined in
1398 =item B<< $metaclass->get_all_methods >>
1400 This will traverse the inheritance hierarchy and return a list of all
1401 the L<Class::MOP::Method> objects for this class and its parents.
1403 =item B<< $metaclass->find_method_by_name($method_name) >>
1405 This will return a L<Class::MOP::Method> for the specified
1406 C<$method_name>. If the class does not have the specified method, it
1409 Unlike C<get_method>, this method I<will> look for the named method in
1412 =item B<< $metaclass->get_all_method_names >>
1414 This will return a list of method I<names> for all of this class's
1415 methods, including inherited methods.
1417 =item B<< $metaclass->find_all_methods_by_name($method_name) >>
1419 This method looks for the named method in the class and all of its
1420 parents. It returns every matching method it finds in the inheritance
1421 tree, so it returns a list of methods.
1423 Each method is returned as a hash reference with three keys. The keys
1424 are C<name>, C<class>, and C<code>. The C<code> key has a
1425 L<Class::MOP::Method> object as its value.
1427 The list of methods is distinct.
1429 =item B<< $metaclass->find_next_method_by_name($method_name) >>
1431 This method returns the first method in any superclass matching the
1432 given name. It is effectively the method that C<SUPER::$method_name>
1435 =item B<< $metaclass->add_method($method_name, $method) >>
1437 This method takes a method name and a subroutine reference, and adds
1438 the method to the class.
1440 The subroutine reference can be a L<Class::MOP::Method>, and you are
1441 strongly encouraged to pass a meta method object instead of a code
1442 reference. If you do so, that object gets stored as part of the
1443 class's method map directly. If not, the meta information will have to
1444 be recreated later, and may be incorrect.
1446 If you provide a method object, this method will clone that object if
1447 the object's package name does not match the class name. This lets us
1448 track the original source of any methods added from other classes
1449 (notably Moose roles).
1451 =item B<< $metaclass->remove_method($method_name) >>
1453 Remove the named method from the class. This method returns the
1454 L<Class::MOP::Method> object for the method.
1456 =item B<< $metaclass->method_metaclass >>
1458 Returns the class name of the method metaclass, see
1459 L<Class::MOP::Method> for more information on the method metaclass.
1461 =item B<< $metaclass->wrapped_method_metaclass >>
1463 Returns the class name of the wrapped method metaclass, see
1464 L<Class::MOP::Method::Wrapped> for more information on the wrapped
1469 =head2 Attribute introspection and creation
1471 Because Perl 5 does not have a core concept of attributes in classes,
1472 we can only return information about attributes which have been added
1473 via this class's methods. We cannot discover information about
1474 attributes which are defined in terms of "regular" Perl 5 methods.
1478 =item B<< $metaclass->get_attribute($attribute_name) >>
1480 This will return a L<Class::MOP::Attribute> for the specified
1481 C<$attribute_name>. If the class does not have the specified
1482 attribute, it returns C<undef>
1484 =item B<< $metaclass->has_attribute($attribute_name) >>
1486 Returns a boolean indicating whether or not the class defines the
1487 named attribute. It does not include attributes inherited from parent
1490 =item B<< $metaclass->get_attribute_map >>
1492 Returns a hash reference representing the attributes defined in this
1493 class. The keys are attribute names and the values are
1494 L<Class::MOP::Attribute> objects.
1496 =item B<< $metaclass->get_attribute_list >>
1498 This will return a list of attributes I<names> for all attributes
1499 defined in this class.
1501 =item B<< $metaclass->get_all_attributes >>
1503 This will traverse the inheritance hierarchy and return a list of all
1504 the L<Class::MOP::Attribute> objects for this class and its parents.
1506 This method can also be called as C<compute_all_applicable_attributes>.
1508 =item B<< $metaclass->find_attribute_by_name($attribute_name) >>
1510 This will return a L<Class::MOP::Attribute> for the specified
1511 C<$attribute_name>. If the class does not have the specified
1512 attribute, it returns C<undef>
1514 Unlike C<get_attribute>, this attribute I<will> look for the named
1515 attribute in superclasses.
1517 =item B<< $metaclass->add_attribute(...) >>
1519 This method accepts either an existing L<Class::MOP::Attribute>
1520 object, or parameters suitable for passing to that class's C<new>
1523 The attribute provided will be added to the class.
1525 Any accessor methods defined by the attribute will be added to the
1526 class when the attribute is added.
1528 If an attribute of the same name already exists, the old attribute
1529 will be removed first.
1531 =item B<< $metaclass->remove_attribute($attribute_name) >>
1533 This will remove the named attribute from the class, and
1534 L<Class::MOP::Attribute> object.
1536 Removing an attribute also removes any accessor methods defined by the
1539 However, note that removing an attribute will only affect I<future>
1540 object instances created for this class, not existing instances.
1542 =item B<< $metaclass->attribute_metaclass >>
1544 Returns the class name of the attribute metaclass for this class. By
1545 default, this is L<Class::MOP::Attribute>. for more information on
1549 =head2 Class Immutability
1551 Making a class immutable "freezes" the class definition. You can no
1552 longer call methods which alter the class, such as adding or removing
1553 methods or attributes.
1555 Making a class immutable lets us optimize the class by inlining some
1556 methods, and also allows us to optimize some methods on the metaclass
1559 The immutabilization system in L<Moose> takes much greater advantage
1560 of the inlining features than Class::MOP itself does.
1564 =item B<< $metaclass->make_immutable(%options) >>
1566 This method will create an immutable transformer and uses it to make
1567 the class and its metaclass object immutable.
1569 Details of how immutabilization works are in L<Class::MOP::Immutable>
1572 =item B<< $metaclass->make_mutable >>
1574 Calling this method reverse the immutabilization transformation.
1576 =item B<< $metaclass->immutable_transformer >>
1578 If the class has been made immutable previously, this returns the
1579 L<Class::MOP::Immutable> object that was created to do the
1582 If the class was never made immutable, this method will die.
1586 =head2 Method Modifiers
1588 Method modifiers are hooks which allow a method to be wrapped with
1589 I<before>, I<after> and I<around> method modifiers. Every time a
1590 method is called, it's modifiers are also called.
1592 A class can modify its own methods, as well as methods defined in
1595 =head3 How method modifiers work?
1597 Method modifiers work by wrapping the original method and then
1598 replacing it in the class's symbol table. The wrappers will handle
1599 calling all the modifiers in the appropriate order and preserving the
1600 calling context for the original method.
1602 The return values of C<before> and C<after> modifiers are
1603 ignored. This is because their purpose is B<not> to filter the input
1604 and output of the primary method (this is done with an I<around>
1607 This may seem like an odd restriction to some, but doing this allows
1608 for simple code to be added at the beginning or end of a method call
1609 without altering the function of the wrapped method or placing any
1610 extra responsibility on the code of the modifier.
1612 Of course if you have more complex needs, you can use the C<around>
1613 modifier which allows you to change both the parameters passed to the
1614 wrapped method, as well as its return value.
1616 Before and around modifiers are called in last-defined-first-called
1617 order, while after modifiers are called in first-defined-first-called
1618 order. So the call tree might looks something like this:
1630 =head3 What is the performance impact?
1632 Of course there is a performance cost associated with method
1633 modifiers, but we have made every effort to make that cost directly
1634 proportional to the number of modifier features you utilize.
1636 The wrapping method does it's best to B<only> do as much work as it
1637 absolutely needs to. In order to do this we have moved some of the
1638 performance costs to set-up time, where they are easier to amortize.
1640 All this said, our benchmarks have indicated the following:
1642 simple wrapper with no modifiers 100% slower
1643 simple wrapper with simple before modifier 400% slower
1644 simple wrapper with simple after modifier 450% slower
1645 simple wrapper with simple around modifier 500-550% slower
1646 simple wrapper with all 3 modifiers 1100% slower
1648 These numbers may seem daunting, but you must remember, every feature
1649 comes with some cost. To put things in perspective, just doing a
1650 simple C<AUTOLOAD> which does nothing but extract the name of the
1651 method called and return it costs about 400% over a normal method
1656 =item B<< $metaclass->add_before_method_modifier($method_name, $code) >>
1658 This wraps the specified method with the supplied subroutine
1659 reference. The modifier will be called as a method itself, and will
1660 receive the same arguments as are passed to the method.
1662 When the modifier exits, the wrapped method will be called.
1664 The return value of the modifier will be ignored.
1666 =item B<< $metaclass->add_after_method_modifier($method_name, $code) >>
1668 This wraps the specified method with the supplied subroutine
1669 reference. The modifier will be called as a method itself, and will
1670 receive the same arguments as are passed to the method.
1672 When the wrapped methods exits, the modifier will be called.
1674 The return value of the modifier will be ignored.
1676 =item B<< $metaclass->add_around_method_modifier($method_name, $code) >>
1678 This wraps the specified method with the supplied subroutine
1681 The first argument passed to the modifier will be a subroutine
1682 reference to the wrapped method. The second argument is the object,
1683 and after that come any arguments passed when the method is called.
1685 The around modifier can choose to call the original method, as well as
1686 what arguments to pass if it does so.
1688 The return value of the modifier is what will be seen by the caller.
1692 =head2 Introspection
1696 =item B<< Class::MOP::Class->meta >>
1698 This will return a L<Class::MOP::Class> instance for this class.
1700 It should also be noted that L<Class::MOP> will actually bootstrap
1701 this module by installing a number of attribute meta-objects into its
1708 Stevan Little E<lt>stevan@iinteractive.comE<gt>
1710 =head1 COPYRIGHT AND LICENSE
1712 Copyright 2006-2009 by Infinity Interactive, Inc.
1714 L<http://www.iinteractive.com>
1716 This library is free software; you can redistribute it and/or modify
1717 it under the same terms as Perl itself.