2 package Class::MOP::Class;
7 use Class::MOP::Immutable;
8 use Class::MOP::Instance;
9 use Class::MOP::Method::Wrapped;
12 use Scalar::Util 'blessed', 'weaken';
14 our $VERSION = '0.78';
15 $VERSION = eval $VERSION;
16 our $AUTHORITY = 'cpan:STEVAN';
18 use base 'Class::MOP::Module';
28 $package_name = shift;
31 $package_name = $options{package};
34 (defined $package_name && $package_name && !ref($package_name))
35 || confess "You must pass a package name and it cannot be blessed";
37 return Class::MOP::get_metaclass_by_name($package_name)
38 || $class->_construct_class_instance(package => $package_name, @_);
41 sub construct_class_instance {
42 warn 'The construct_class_instance method has been made private.'
43 . " The public version is deprecated and will be removed in a future release.\n";
44 goto &_construct_class_instance;
47 # NOTE: (meta-circularity)
48 # this is a special form of &construct_instance
49 # (see below), which is used to construct class
50 # meta-object instances for any Class::MOP::*
51 # class. All other classes will use the more
52 # normal &construct_instance.
53 sub _construct_class_instance {
55 my $options = @_ == 1 ? $_[0] : {@_};
56 my $package_name = $options->{package};
57 (defined $package_name && $package_name)
58 || confess "You must pass a package name";
60 # return the metaclass if we have it cached,
61 # and it is still defined (it has not been
62 # reaped by DESTROY yet, which can happen
63 # annoyingly enough during global destruction)
65 if (defined(my $meta = Class::MOP::get_metaclass_by_name($package_name))) {
70 # we need to deal with the possibility
71 # of class immutability here, and then
72 # get the name of the class appropriately
74 ? ($class->is_immutable
75 ? $class->get_mutable_metaclass_name()
79 # now create the metaclass
81 if ($class eq 'Class::MOP::Class') {
83 $meta = $class->_new($options)
87 # it is safe to use meta here because
88 # class will always be a subclass of
89 # Class::MOP::Class, which defines meta
90 $meta = $class->meta->construct_instance($options)
93 # and check the metaclass compatibility
94 $meta->check_metaclass_compatibility();
96 Class::MOP::store_metaclass_by_name($package_name, $meta);
99 # we need to weaken any anon classes
100 # so that they can call DESTROY properly
101 Class::MOP::weaken_metaclass($package_name) if $meta->is_anon_class;
108 my $options = @_ == 1 ? $_[0] : {@_};
111 # inherited from Class::MOP::Package
112 'package' => $options->{package},
115 # since the following attributes will
116 # actually be loaded from the symbol
117 # table, and actually bypass the instance
118 # entirely, we can just leave these things
119 # listed here for reference, because they
120 # should not actually have a value associated
122 'namespace' => \undef,
124 # inherited from Class::MOP::Module
126 'authority' => \undef,
128 # defined in Class::MOP::Class
129 'superclasses' => \undef,
133 'attribute_metaclass' => $options->{'attribute_metaclass'}
134 || 'Class::MOP::Attribute',
135 'method_metaclass' => $options->{'method_metaclass'}
136 || 'Class::MOP::Method',
137 'wrapped_method_metaclass' => $options->{'wrapped_method_metaclass'}
138 || 'Class::MOP::Method::Wrapped',
139 'instance_metaclass' => $options->{'instance_metaclass'}
140 || 'Class::MOP::Instance',
144 sub reset_package_cache_flag { (shift)->{'_package_cache_flag'} = undef }
145 sub update_package_cache_flag {
148 # we can manually update the cache number
149 # since we are actually adding the method
150 # to our cache as well. This avoids us
151 # having to regenerate the method_map.
153 $self->{'_package_cache_flag'} = Class::MOP::check_package_cache_flag($self->name);
156 sub check_metaclass_compatibility {
159 # this is always okay ...
160 return if ref($self) eq 'Class::MOP::Class' &&
161 $self->instance_metaclass eq 'Class::MOP::Instance';
163 my @class_list = $self->linearized_isa;
164 shift @class_list; # shift off $self->name
166 foreach my $superclass_name (@class_list) {
167 my $super_meta = Class::MOP::get_metaclass_by_name($superclass_name) || next;
170 # we need to deal with the possibility
171 # of class immutability here, and then
172 # get the name of the class appropriately
174 = $super_meta->is_immutable
175 ? $super_meta->get_mutable_metaclass_name()
178 ($self->isa($super_meta_type))
179 || confess $self->name . "->meta => (" . (ref($self)) . ")" .
180 " is not compatible with the " .
181 $superclass_name . "->meta => (" . ($super_meta_type) . ")";
183 # we also need to check that instance metaclasses
184 # are compatibile in the same the class.
185 ($self->instance_metaclass->isa($super_meta->instance_metaclass))
186 || confess $self->name . "->meta->instance_metaclass => (" . ($self->instance_metaclass) . ")" .
187 " is not compatible with the " .
188 $superclass_name . "->meta->instance_metaclass => (" . ($super_meta->instance_metaclass) . ")";
196 # this should be sufficient, if you have a
197 # use case where it is not, write a test and
199 my $ANON_CLASS_SERIAL = 0;
202 # we need a sufficiently annoying prefix
203 # this should suffice for now, this is
204 # used in a couple of places below, so
205 # need to put it up here for now.
206 my $ANON_CLASS_PREFIX = 'Class::MOP::Class::__ANON__::SERIAL::';
210 no warnings 'uninitialized';
211 $self->name =~ /^$ANON_CLASS_PREFIX/;
214 sub create_anon_class {
215 my ($class, %options) = @_;
216 my $package_name = $ANON_CLASS_PREFIX . ++$ANON_CLASS_SERIAL;
217 return $class->create($package_name, %options);
221 # this will only get called for
222 # anon-classes, all other calls
223 # are assumed to occur during
224 # global destruction and so don't
225 # really need to be handled explicitly
229 return if Class::MOP::in_global_destruction(); # it'll happen soon anyway and this just makes things more complicated
231 no warnings 'uninitialized';
232 return unless $self->name =~ /^$ANON_CLASS_PREFIX/;
233 # Moose does a weird thing where it replaces the metaclass for
234 # class when fixing metaclass incompatibility. In that case,
235 # we don't want to clean out the namespace now. We can detect
236 # that because Moose will explicitly update the singleton
237 # cache in Class::MOP.
238 my $current_meta = Class::MOP::get_metaclass_by_name($self->name);
239 return if $current_meta ne $self;
241 my ($serial_id) = ($self->name =~ /^$ANON_CLASS_PREFIX(\d+)/);
243 foreach my $key (keys %{$ANON_CLASS_PREFIX . $serial_id}) {
244 delete ${$ANON_CLASS_PREFIX . $serial_id}{$key};
246 delete ${'main::' . $ANON_CLASS_PREFIX}{$serial_id . '::'};
251 # creating classes with MOP ...
254 my ( $class, @args ) = @_;
256 unshift @args, 'package' if @args % 2 == 1;
258 my (%options) = @args;
259 my $package_name = $options{package};
261 (ref $options{superclasses} eq 'ARRAY')
262 || confess "You must pass an ARRAY ref of superclasses"
263 if exists $options{superclasses};
265 (ref $options{attributes} eq 'ARRAY')
266 || confess "You must pass an ARRAY ref of attributes"
267 if exists $options{attributes};
269 (ref $options{methods} eq 'HASH')
270 || confess "You must pass a HASH ref of methods"
271 if exists $options{methods};
273 $class->SUPER::create(%options);
275 my (%initialize_options) = @args;
276 delete @initialize_options{qw(
284 my $meta = $class->initialize( $package_name => %initialize_options );
287 $meta->add_method('meta' => sub {
288 $class->initialize(ref($_[0]) || $_[0]);
291 $meta->superclasses(@{$options{superclasses}})
292 if exists $options{superclasses};
294 # process attributes first, so that they can
295 # install accessors, but locally defined methods
296 # can then overwrite them. It is maybe a little odd, but
297 # I think this should be the order of things.
298 if (exists $options{attributes}) {
299 foreach my $attr (@{$options{attributes}}) {
300 $meta->add_attribute($attr);
303 if (exists $options{methods}) {
304 foreach my $method_name (keys %{$options{methods}}) {
305 $meta->add_method($method_name, $options{methods}->{$method_name});
314 # all these attribute readers will be bootstrapped
315 # away in the Class::MOP bootstrap section
317 sub get_attribute_map { $_[0]->{'attributes'} }
318 sub attribute_metaclass { $_[0]->{'attribute_metaclass'} }
319 sub method_metaclass { $_[0]->{'method_metaclass'} }
320 sub wrapped_method_metaclass { $_[0]->{'wrapped_method_metaclass'} }
321 sub instance_metaclass { $_[0]->{'instance_metaclass'} }
323 # Instance Construction & Cloning
329 # we need to protect the integrity of the
330 # Class::MOP::Class singletons here, so we
331 # delegate this to &construct_class_instance
332 # which will deal with the singletons
333 return $class->_construct_class_instance(@_)
334 if $class->name->isa('Class::MOP::Class');
335 return $class->construct_instance(@_);
338 sub construct_instance {
340 my $params = @_ == 1 ? $_[0] : {@_};
341 my $meta_instance = $class->get_meta_instance();
342 my $instance = $meta_instance->create_instance();
343 foreach my $attr ($class->compute_all_applicable_attributes()) {
344 $attr->initialize_instance_slot($meta_instance, $instance, $params);
347 # this will only work for a HASH instance type
348 if ($class->is_anon_class) {
349 (Scalar::Util::reftype($instance) eq 'HASH')
350 || confess "Currently only HASH based instances are supported with instance of anon-classes";
352 # At some point we should make this official
353 # as a reserved slot name, but right now I am
354 # going to keep it here.
355 # my $RESERVED_MOP_SLOT = '__MOP__';
356 $instance->{'__MOP__'} = $class;
362 sub get_meta_instance {
364 $self->{'_meta_instance'} ||= $self->create_meta_instance();
367 sub create_meta_instance {
370 my $instance = $self->instance_metaclass->new(
371 associated_metaclass => $self,
372 attributes => [ $self->compute_all_applicable_attributes() ],
375 $self->add_meta_instance_dependencies()
376 if $instance->is_dependent_on_superclasses();
383 my $instance = shift;
384 (blessed($instance) && $instance->isa($class->name))
385 || confess "You must pass an instance of the metaclass (" . (ref $class ? $class->name : $class) . "), not ($instance)";
388 # we need to protect the integrity of the
389 # Class::MOP::Class singletons here, they
390 # should not be cloned.
391 return $instance if $instance->isa('Class::MOP::Class');
392 $class->clone_instance($instance, @_);
396 my ($class, $instance, %params) = @_;
398 || confess "You can only clone instances, ($instance) is not a blessed instance";
399 my $meta_instance = $class->get_meta_instance();
400 my $clone = $meta_instance->clone_instance($instance);
401 foreach my $attr ($class->compute_all_applicable_attributes()) {
402 if ( defined( my $init_arg = $attr->init_arg ) ) {
403 if (exists $params{$init_arg}) {
404 $attr->set_value($clone, $params{$init_arg});
411 sub rebless_instance {
412 my ($self, $instance, %params) = @_;
415 if ($instance->can('meta')) {
416 ($instance->meta->isa('Class::MOP::Class'))
417 || confess 'Cannot rebless instance if ->meta is not an instance of Class::MOP::Class';
418 $old_metaclass = $instance->meta;
421 $old_metaclass = $self->initialize(ref($instance));
424 my $meta_instance = $self->get_meta_instance();
426 $self->name->isa($old_metaclass->name)
427 || confess "You may rebless only into a subclass of (". $old_metaclass->name ."), of which (". $self->name .") isn't.";
430 # we use $_[1] here because of t/306_rebless_overload.t regressions on 5.8.8
431 $meta_instance->rebless_instance_structure($_[1], $self);
433 foreach my $attr ( $self->compute_all_applicable_attributes ) {
434 if ( $attr->has_value($instance) ) {
435 if ( defined( my $init_arg = $attr->init_arg ) ) {
436 $params{$init_arg} = $attr->get_value($instance)
437 unless exists $params{$init_arg};
440 $attr->set_value($instance, $attr->get_value($instance));
445 foreach my $attr ($self->compute_all_applicable_attributes) {
446 $attr->initialize_instance_slot($meta_instance, $instance, \%params);
456 my $var_spec = { sigil => '@', type => 'ARRAY', name => 'ISA' };
459 @{$self->get_package_symbol($var_spec)} = @supers;
462 # on 5.8 and below, we need to call
463 # a method to get Perl to detect
464 # a cycle in the class hierarchy
465 my $class = $self->name;
469 # we need to check the metaclass
470 # compatibility here so that we can
471 # be sure that the superclass is
472 # not potentially creating an issues
473 # we don't know about
475 $self->check_metaclass_compatibility();
476 $self->update_meta_instance_dependencies();
478 @{$self->get_package_symbol($var_spec)};
484 my $super_class = $self->name;
486 if ( Class::MOP::HAVE_ISAREV() ) {
487 return @{ $super_class->mro::get_isarev() };
491 my $find_derived_classes;
492 $find_derived_classes = sub {
493 my ($outer_class) = @_;
495 my $symbol_table_hashref = do { no strict 'refs'; \%{"${outer_class}::"} };
498 for my $symbol ( keys %$symbol_table_hashref ) {
499 next SYMBOL if $symbol !~ /\A (\w+):: \z/x;
500 my $inner_class = $1;
502 next SYMBOL if $inner_class eq 'SUPER'; # skip '*::SUPER'
506 ? "${outer_class}::$inner_class"
509 if ( $class->isa($super_class) and $class ne $super_class ) {
510 push @derived_classes, $class;
513 next SYMBOL if $class eq 'main'; # skip 'main::*'
515 $find_derived_classes->($class);
519 my $root_class = q{};
520 $find_derived_classes->($root_class);
522 undef $find_derived_classes;
524 @derived_classes = sort { $a->isa($b) ? 1 : $b->isa($a) ? -1 : 0 } @derived_classes;
526 return @derived_classes;
532 return @{ mro::get_linear_isa( (shift)->name ) };
535 sub class_precedence_list {
537 my $name = $self->name;
539 unless (Class::MOP::IS_RUNNING_ON_5_10()) {
541 # We need to check for circular inheritance here
542 # if we are are not on 5.10, cause 5.8 detects it
543 # late. This will do nothing if all is well, and
544 # blow up otherwise. Yes, it's an ugly hack, better
545 # suggestions are welcome.
547 ($name || return)->isa('This is a test for circular inheritance')
550 # if our mro is c3, we can
551 # just grab the linear_isa
552 if (mro::get_mro($name) eq 'c3') {
553 return @{ mro::get_linear_isa($name) }
557 # we can't grab the linear_isa for dfs
558 # since it has all the duplicates
563 $self->initialize($_)->class_precedence_list()
564 } $self->superclasses()
571 sub wrap_method_body {
572 my ( $self, %args ) = @_;
574 ('CODE' eq ref $args{body})
575 || confess "Your code block must be a CODE reference";
577 $self->method_metaclass->wrap(
578 package_name => $self->name,
584 my ($self, $method_name, $method) = @_;
585 (defined $method_name && $method_name)
586 || confess "You must define a method name";
589 if (blessed($method)) {
590 $body = $method->body;
591 if ($method->package_name ne $self->name) {
592 $method = $method->clone(
593 package_name => $self->name,
595 ) if $method->can('clone');
600 $method = $self->wrap_method_body( body => $body, name => $method_name );
603 $method->attach_to_class($self);
605 # This used to call get_method_map, which meant we would build all
606 # the method objects for the class just because we added one
607 # method. This is hackier, but quicker too.
608 $self->{methods}{$method_name} = $method;
610 my $full_method_name = ($self->name . '::' . $method_name);
611 $self->add_package_symbol(
612 { sigil => '&', type => 'CODE', name => $method_name },
613 Class::MOP::subname($full_method_name => $body)
618 my $fetch_and_prepare_method = sub {
619 my ($self, $method_name) = @_;
620 my $wrapped_metaclass = $self->wrapped_method_metaclass;
622 my $method = $self->get_method($method_name);
623 # if we dont have local ...
625 # try to find the next method
626 $method = $self->find_next_method_by_name($method_name);
627 # die if it does not exist
629 || confess "The method '$method_name' was not found in the inheritance hierarchy for " . $self->name;
630 # and now make sure to wrap it
631 # even if it is already wrapped
632 # because we need a new sub ref
633 $method = $wrapped_metaclass->wrap($method);
636 # now make sure we wrap it properly
637 $method = $wrapped_metaclass->wrap($method)
638 unless $method->isa($wrapped_metaclass);
640 $self->add_method($method_name => $method);
644 sub add_before_method_modifier {
645 my ($self, $method_name, $method_modifier) = @_;
646 (defined $method_name && $method_name)
647 || confess "You must pass in a method name";
648 my $method = $fetch_and_prepare_method->($self, $method_name);
649 $method->add_before_modifier(
650 Class::MOP::subname(':before' => $method_modifier)
654 sub add_after_method_modifier {
655 my ($self, $method_name, $method_modifier) = @_;
656 (defined $method_name && $method_name)
657 || confess "You must pass in a method name";
658 my $method = $fetch_and_prepare_method->($self, $method_name);
659 $method->add_after_modifier(
660 Class::MOP::subname(':after' => $method_modifier)
664 sub add_around_method_modifier {
665 my ($self, $method_name, $method_modifier) = @_;
666 (defined $method_name && $method_name)
667 || confess "You must pass in a method name";
668 my $method = $fetch_and_prepare_method->($self, $method_name);
669 $method->add_around_modifier(
670 Class::MOP::subname(':around' => $method_modifier)
675 # the methods above used to be named like this:
676 # ${pkg}::${method}:(before|after|around)
677 # but this proved problematic when using one modifier
678 # to wrap multiple methods (something which is likely
679 # to happen pretty regularly IMO). So instead of naming
680 # it like this, I have chosen to just name them purely
681 # with their modifier names, like so:
682 # :(before|after|around)
683 # The fact is that in a stack trace, it will be fairly
684 # evident from the context what method they are attached
685 # to, and so don't need the fully qualified name.
691 $self->add_method(@_);
695 my ($self, $method_name) = @_;
696 (defined $method_name && $method_name)
697 || confess "You must define a method name";
699 exists $self->{methods}{$method_name} || exists $self->get_method_map->{$method_name};
703 my ($self, $method_name) = @_;
704 (defined $method_name && $method_name)
705 || confess "You must define a method name";
707 return $self->{methods}{$method_name} || $self->get_method_map->{$method_name};
711 my ($self, $method_name) = @_;
712 (defined $method_name && $method_name)
713 || confess "You must define a method name";
715 my $removed_method = delete $self->get_method_map->{$method_name};
717 $self->remove_package_symbol(
718 { sigil => '&', type => 'CODE', name => $method_name }
721 $removed_method->detach_from_class if $removed_method;
723 $self->update_package_cache_flag; # still valid, since we just removed the method from the map
725 return $removed_method;
728 sub get_method_list {
730 keys %{$self->get_method_map};
733 sub find_method_by_name {
734 my ($self, $method_name) = @_;
735 (defined $method_name && $method_name)
736 || confess "You must define a method name to find";
737 foreach my $class ($self->linearized_isa) {
738 # fetch the meta-class ...
739 my $meta = $self->initialize($class);
740 return $meta->get_method($method_name)
741 if $meta->has_method($method_name);
746 sub get_all_methods {
748 my %methods = map { %{ $self->initialize($_)->get_method_map } } reverse $self->linearized_isa;
749 return values %methods;
753 sub compute_all_applicable_methods {
757 class => $_->package_name,
758 code => $_, # sigh, overloading
760 } shift->get_all_methods(@_);
763 sub get_all_method_names {
766 grep { $uniq{$_}++ == 0 } map { $_->name } $self->get_all_methods;
769 sub find_all_methods_by_name {
770 my ($self, $method_name) = @_;
771 (defined $method_name && $method_name)
772 || confess "You must define a method name to find";
774 foreach my $class ($self->linearized_isa) {
775 # fetch the meta-class ...
776 my $meta = $self->initialize($class);
778 name => $method_name,
780 code => $meta->get_method($method_name)
781 } if $meta->has_method($method_name);
786 sub find_next_method_by_name {
787 my ($self, $method_name) = @_;
788 (defined $method_name && $method_name)
789 || confess "You must define a method name to find";
790 my @cpl = $self->linearized_isa;
791 shift @cpl; # discard ourselves
792 foreach my $class (@cpl) {
793 # fetch the meta-class ...
794 my $meta = $self->initialize($class);
795 return $meta->get_method($method_name)
796 if $meta->has_method($method_name);
805 # either we have an attribute object already
806 # or we need to create one from the args provided
807 my $attribute = blessed($_[0]) ? $_[0] : $self->attribute_metaclass->new(@_);
808 # make sure it is derived from the correct type though
809 ($attribute->isa('Class::MOP::Attribute'))
810 || confess "Your attribute must be an instance of Class::MOP::Attribute (or a subclass)";
812 # first we attach our new attribute
813 # because it might need certain information
814 # about the class which it is attached to
815 $attribute->attach_to_class($self);
817 # then we remove attributes of a conflicting
818 # name here so that we can properly detach
819 # the old attr object, and remove any
820 # accessors it would have generated
821 if ( $self->has_attribute($attribute->name) ) {
822 $self->remove_attribute($attribute->name);
824 $self->invalidate_meta_instances();
827 # then onto installing the new accessors
828 $self->get_attribute_map->{$attribute->name} = $attribute;
830 # invalidate package flag here
831 my $e = do { local $@; eval { $attribute->install_accessors() }; $@ };
833 $self->remove_attribute($attribute->name);
840 sub update_meta_instance_dependencies {
843 if ( $self->{meta_instance_dependencies} ) {
844 return $self->add_meta_instance_dependencies;
848 sub add_meta_instance_dependencies {
851 $self->remove_meta_instance_dependencies;
853 my @attrs = $self->compute_all_applicable_attributes();
856 my @classes = grep { not $seen{$_->name}++ } map { $_->associated_class } @attrs;
858 foreach my $class ( @classes ) {
859 $class->add_dependent_meta_instance($self);
862 $self->{meta_instance_dependencies} = \@classes;
865 sub remove_meta_instance_dependencies {
868 if ( my $classes = delete $self->{meta_instance_dependencies} ) {
869 foreach my $class ( @$classes ) {
870 $class->remove_dependent_meta_instance($self);
880 sub add_dependent_meta_instance {
881 my ( $self, $metaclass ) = @_;
882 push @{ $self->{dependent_meta_instances} }, $metaclass;
885 sub remove_dependent_meta_instance {
886 my ( $self, $metaclass ) = @_;
887 my $name = $metaclass->name;
888 @$_ = grep { $_->name ne $name } @$_ for $self->{dependent_meta_instances};
891 sub invalidate_meta_instances {
893 $_->invalidate_meta_instance() for $self, @{ $self->{dependent_meta_instances} };
896 sub invalidate_meta_instance {
898 undef $self->{_meta_instance};
902 my ($self, $attribute_name) = @_;
903 (defined $attribute_name && $attribute_name)
904 || confess "You must define an attribute name";
905 exists $self->get_attribute_map->{$attribute_name};
909 my ($self, $attribute_name) = @_;
910 (defined $attribute_name && $attribute_name)
911 || confess "You must define an attribute name";
912 return $self->get_attribute_map->{$attribute_name}
914 # this will return undef anyway, so no need ...
915 # if $self->has_attribute($attribute_name);
919 sub remove_attribute {
920 my ($self, $attribute_name) = @_;
921 (defined $attribute_name && $attribute_name)
922 || confess "You must define an attribute name";
923 my $removed_attribute = $self->get_attribute_map->{$attribute_name};
924 return unless defined $removed_attribute;
925 delete $self->get_attribute_map->{$attribute_name};
926 $self->invalidate_meta_instances();
927 $removed_attribute->remove_accessors();
928 $removed_attribute->detach_from_class();
929 return $removed_attribute;
932 sub get_attribute_list {
934 keys %{$self->get_attribute_map};
937 sub get_all_attributes {
938 shift->compute_all_applicable_attributes(@_);
941 sub compute_all_applicable_attributes {
943 my %attrs = map { %{ $self->initialize($_)->get_attribute_map } } reverse $self->linearized_isa;
944 return values %attrs;
947 sub find_attribute_by_name {
948 my ($self, $attr_name) = @_;
949 foreach my $class ($self->linearized_isa) {
950 # fetch the meta-class ...
951 my $meta = $self->initialize($class);
952 return $meta->get_attribute($attr_name)
953 if $meta->has_attribute($attr_name);
958 # check if we can reinitialize
962 # if any local attr is defined
963 return if $self->get_attribute_list;
965 # or any non-declared methods
966 if ( my @methods = values %{ $self->get_method_map } ) {
967 my $metaclass = $self->method_metaclass;
968 foreach my $method ( @methods ) {
969 return if $method->isa("Class::MOP::Method::Generated");
970 # FIXME do we need to enforce this too? return unless $method->isa($metaclass);
980 sub is_immutable { 0 }
983 # Why I changed this (groditi)
984 # - One Metaclass may have many Classes through many Metaclass instances
985 # - One Metaclass should only have one Immutable Transformer instance
986 # - Each Class may have different Immutabilizing options
987 # - Therefore each Metaclass instance may have different Immutabilizing options
988 # - We need to store one Immutable Transformer instance per Metaclass
989 # - We need to store one set of Immutable Transformer options per Class
990 # - Upon make_mutable we may delete the Immutabilizing options
991 # - We could clean the immutable Transformer instance when there is no more
992 # immutable Classes of that type, but we can also keep it in case
993 # another class with this same Metaclass becomes immutable. It is a case
994 # of trading of storing an instance to avoid unnecessary instantiations of
995 # Immutable Transformers. You may view this as a memory leak, however
996 # Because we have few Metaclasses, in practice it seems acceptable
997 # - To allow Immutable Transformers instances to be cleaned up we could weaken
998 # the reference stored in $IMMUTABLE_TRANSFORMERS{$class} and ||= should DWIM
1002 my %IMMUTABLE_TRANSFORMERS;
1003 my %IMMUTABLE_OPTIONS;
1005 sub get_immutable_options {
1007 return if $self->is_mutable;
1008 confess "unable to find immutabilizing options"
1009 unless exists $IMMUTABLE_OPTIONS{$self->name};
1010 my %options = %{$IMMUTABLE_OPTIONS{$self->name}};
1011 delete $options{IMMUTABLE_TRANSFORMER};
1015 sub get_immutable_transformer {
1017 if( $self->is_mutable ){
1018 return $IMMUTABLE_TRANSFORMERS{$self->name} ||= $self->create_immutable_transformer;
1020 confess "unable to find transformer for immutable class"
1021 unless exists $IMMUTABLE_OPTIONS{$self->name};
1022 return $IMMUTABLE_OPTIONS{$self->name}->{IMMUTABLE_TRANSFORMER};
1025 sub make_immutable {
1029 my $transformer = $self->get_immutable_transformer;
1030 $transformer->make_metaclass_immutable($self, \%options);
1031 $IMMUTABLE_OPTIONS{$self->name} =
1032 { %options, IMMUTABLE_TRANSFORMER => $transformer };
1034 if( exists $options{debug} && $options{debug} ){
1035 print STDERR "# of Metaclass options: ", keys %IMMUTABLE_OPTIONS;
1036 print STDERR "# of Immutable transformers: ", keys %IMMUTABLE_TRANSFORMERS;
1044 return if $self->is_mutable;
1045 my $options = delete $IMMUTABLE_OPTIONS{$self->name};
1046 confess "unable to find immutabilizing options" unless ref $options;
1047 my $transformer = delete $options->{IMMUTABLE_TRANSFORMER};
1048 $transformer->make_metaclass_mutable($self, $options);
1053 sub create_immutable_transformer {
1055 my $class = Class::MOP::Immutable->new($self, {
1056 read_only => [qw/superclasses/],
1063 remove_package_symbol
1066 class_precedence_list => 'ARRAY',
1067 linearized_isa => 'ARRAY', # FIXME perl 5.10 memoizes this on its own, no need?
1068 get_all_methods => 'ARRAY',
1069 get_all_method_names => 'ARRAY',
1070 #get_all_attributes => 'ARRAY', # it's an alias, no need, but maybe in the future
1071 compute_all_applicable_attributes => 'ARRAY',
1072 get_meta_instance => 'SCALAR',
1073 get_method_map => 'SCALAR',
1076 # this is ugly, but so are typeglobs,
1077 # so whattayahgonnadoboutit
1080 add_package_symbol => sub {
1081 my $original = shift;
1082 confess "Cannot add package symbols to an immutable metaclass"
1083 unless (caller(2))[3] eq 'Class::MOP::Package::get_package_symbol';
1085 # This is a workaround for a bug in 5.8.1 which thinks that
1086 # goto $original->body
1087 # is trying to go to a label
1088 my $body = $original->body;
1104 Class::MOP::Class - Class Meta Object
1108 # assuming that class Foo
1109 # has been defined, you can
1111 # use this for introspection ...
1113 # add a method to Foo ...
1114 Foo->meta->add_method( 'bar' => sub {...} )
1116 # get a list of all the classes searched
1117 # the method dispatcher in the correct order
1118 Foo->meta->class_precedence_list()
1120 # remove a method from Foo
1121 Foo->meta->remove_method('bar');
1123 # or use this to actually create classes ...
1125 Class::MOP::Class->create(
1128 superclasses => ['Foo'],
1130 Class::MOP:: : Attribute->new('$bar'),
1131 Class::MOP:: : Attribute->new('$baz'),
1134 calculate_bar => sub {...},
1135 construct_baz => sub {...}
1142 This is the largest and most complex part of the Class::MOP
1143 meta-object protocol. It controls the introspection and manipulation
1144 of Perl 5 classes, and it can create them as wlel. The best way to
1145 understand what this module can do, is to read the documentation for
1146 each of its methods.
1150 C<Class::MOP::Class> is a subclass of L<Class::MOP::Module>.
1154 =head2 Class construction
1156 These methods all create new C<Class::MOP::Class> objects. These
1157 objects can represent existing classes, or they can be used to create
1158 new classes from scratch.
1160 The metaclass object for a given class is a singleton. If you attempt
1161 to create a metaclass for the same class twice, you will just get the
1166 =item B<< Class::MOP::Class->create($package_name, %options) >>
1168 This method creates a new C<Class::MOP::Class> object with the given
1169 package name. It accepts a number of options.
1175 An optional version number for the newly created package.
1179 An optional authority for the newly created package.
1181 =item * superclasses
1183 An optional array reference of superclass names.
1187 An optional hash reference of methods for the class. The keys of the
1188 hash reference are method names, and values are subroutine references.
1192 An optional array reference of attributes.
1194 An attribute can be passed as an existing L<Class::MOP::Attribute>
1195 object, I<or> or as a hash reference of options which will be passed
1196 to the attribute metaclass's constructor.
1200 =item B<< Class::MOP::Class->create_anon_class(%options) >>
1202 This method works just like C<< Class::MOP::Class->create >> but it
1203 creates an "anonymous" class. In fact, the class does have a name, but
1204 that name is a unique name generated internally by this module.
1206 It accepts the same C<superclasses>, C<methods>, and C<attributes>
1207 parameters that C<create> accepts.
1209 Anonymous classes are destroyed once the metaclass they are attached
1210 to goes out of scope, and will be removed from Perl's internal symbol
1213 All instances of an anonymous class keep a special reference to the
1214 metaclass object, which prevents the metaclass from going out of scope
1215 while any instances exist.
1217 This only works if the instance if based on a hash reference, however.
1219 =item B<< Class::MOP::Class->initialize($package_name, %options) >>
1221 This method will initialize a C<Class::MOP::Class> object for the
1222 named package. Unlike C<create>, this method I<will not> create a new
1225 The purpose of this method is to retrieve a C<Class::MOP::Class>
1226 object for introspecting an existing class.
1228 If an existing C<Class::MOP::Class> object exists for the named
1229 package, it will be returned, and any options provided will be
1232 If the object does not yet exist, it will be created.
1234 The valid options that can be passed to this method are
1235 C<attribute_metaclass>, C<method_metaclass>,
1236 C<wrapped_method_metaclass>, and C<instance_metaclass>. These are all
1237 optional, and default to the appropriate class in the C<Class::MOP>
1242 =head2 Object instance construction and cloning
1244 These methods are all related to creating and/or cloning object
1249 =item B<< $metaclass->clone_object($instance, %params) >>
1251 This method clones an existing object instance. Any parameters you
1252 provide are will override existing attribute values in the object.
1254 This is a convience method for cloning an object instance, then
1255 blessing it into the appropriate package.
1257 You could implement a clone method in your class, using this method:
1260 my ($self, %params) = @_;
1261 $self->meta->clone_object($self, %params);
1264 =item B<< $metaclass->rebless_instance($instance, %params) >>
1266 This method changes the class of C<$instance> to the metaclass's class.
1268 You can only rebless an instance into a subclass of its current
1269 class. If you pass any additional parameters, these will be treated
1270 like constructor parameters and used to initialize the object's
1271 attributes. Any existing attributes that are already set will be
1274 =item B<< $metaclass->new_object(%params) >>
1276 This method is used to create a new object of the metaclass's
1277 class. Any parameters you provide are used to initialize the
1278 instance's attributes.
1280 =item B<< $metaclass->instance_metaclass >>
1282 Returns the class name of the instance metaclass, see
1283 L<Class::MOP::Instance> for more information on the instance
1286 =item B<< $metaclass->get_meta_instance >>
1288 Returns an instance of the C<instance_metaclass> to be used in the
1289 construction of a new instance of the class.
1293 =head2 Informational predicates
1295 These are a few predicate methods for asking information about the
1300 =item B<< $metaclass->is_anon_class >>
1302 This returns true if the class was created by calling C<<
1303 Class::MOP::Class->create_anon_class >>.
1305 =item B<< $metaclass->is_mutable >>
1307 This returns true if the class is still mutable.
1309 =item B<< $metaclass->is_immutable >>
1311 This returns true if the class has been made immutable.
1313 =item B<< $metaclass->is_pristine >>
1315 A class is I<not> pristine if it has non-inherited attributes or if it
1316 has any generated methods.
1320 =head2 Inheritance Relationships
1324 =item B<< $metaclass->superclasses(@superclasses) >>
1326 This is a read-write accessor which represents the superclass
1327 relationships of the metaclass's class.
1329 This is basically sugar around getting and setting C<@ISA>.
1331 =item B<< $metaclass->class_precedence_list >>
1333 This returns a list of all of the class's ancestor classes. The
1334 classes are returned in method dispatch order.
1336 =item B<< $metaclass->linearized_isa >>
1338 This returns a list based on C<class_precedence_list> but with all
1341 =item B<< $metaclass->subclasses >>
1343 This returns a list of subclasses for this class.
1347 =head2 Method introspection and creation
1349 These methods allow you to introspect a class's methods, as well as
1350 add, remove, or change methods.
1352 Determining what is truly a method in a Perl 5 class requires some
1353 heuristics (aka guessing).
1355 Methods defined outside the package with a fully qualified name (C<sub
1356 Package::name { ... }>) will be included. Similarly, methods named
1357 with a fully qualified name using L<Sub::Name> are also included.
1359 However, we attempt to ignore imported functions.
1361 Ultimately, we are using heuristics to determine what truly is a
1362 method in a class, and these heuristics may get the wrong answer in
1363 some edge cases. However, for most "normal" cases the heuristics work
1368 =item B<< $metaclass->get_method($method_name) >>
1370 This will return a L<Class::MOP::Method> for the specified
1371 C<$method_name>. If the class does not have the specified method, it
1374 =item B<< $metaclass->has_method($method_name) >>
1376 Returns a boolean indicating whether or not the class defines the
1377 named method. It does not include methods inherited from parent
1380 =item B<< $metaclass->get_method_map >>
1382 Returns a hash reference representing the methods defined in this
1383 class. The keys are method names and the values are
1384 L<Class::MOP::Method> objects.
1386 =item B<< $metaclass->get_method_list >>
1388 This will return a list of method I<names> for all methods defined in
1391 =item B<< $metaclass->get_all_methods >>
1393 This will traverse the inheritance hierarchy and return a list of all
1394 the L<Class::MOP::Method> objects for this class and its parents.
1396 =item B<< $metaclass->find_method_by_name($method_name) >>
1398 This will return a L<Class::MOP::Method> for the specified
1399 C<$method_name>. If the class does not have the specified method, it
1402 Unlike C<get_method>, this method I<will> look for the named method in
1405 =item B<< $metaclass->get_all_method_names >>
1407 This will return a list of method I<names> for all of this class's
1408 methods, including inherited methods.
1410 =item B<< $metaclass->find_all_methods_by_name($method_name) >>
1412 This method looks for the named method in the class and all of its
1413 parents. It returns every matching method it finds in the inheritance
1414 tree, so it returns a list of methods.
1416 Each method is returned as a hash reference with three keys. The keys
1417 are C<name>, C<class>, and C<code>. The C<code> key has a
1418 L<Class::MOP::Method> object as its value.
1420 The list of methods is distinct.
1422 =item B<< $metaclass->find_next_method_by_name($method_name) >>
1424 This method returns the first method in any superclass matching the
1425 given name. It is effectively the method that C<SUPER::$method_name>
1428 =item B<< $metaclass->add_method($method_name, $method) >>
1430 This method takes a method name and a subroutine reference, and adds
1431 the method to the class.
1433 The subroutine reference can be a L<Class::MOP::Method>, and you are
1434 strongly encouraged to pass a meta method object instead of a code
1435 reference. If you do so, that object gets stored as part of the
1436 class's method map directly. If not, the meta information will have to
1437 be recreated later, and may be incorrect.
1439 If you provide a method object, this method will clone that object if
1440 the object's package name does not match the class name. This lets us
1441 track the original source of any methods added from other classes
1442 (notably Moose roles).
1444 =item B<< $metaclass->remove_method($method_name) >>
1446 Remove the named method from the class. This method returns the
1447 L<Class::MOP::Method> object for the method.
1451 =head2 Attribute introspection and creation
1453 Because Perl 5 does not have a core concept of attributes in classes,
1454 we can only return information about attributes which have been added
1455 via this class's methods. We cannot discover information about
1456 attributes which are defined in terms of "regular" Perl 5 methods.
1460 =item B<< $metaclass->get_attribute($attribute_name) >>
1462 This will return a L<Class::MOP::Attribute> for the specified
1463 C<$attribute_name>. If the class does not have the specified
1464 attribute, it returns C<undef>
1466 =item B<< $metaclass->has_attribute($attribute_name) >>
1468 Returns a boolean indicating whether or not the class defines the
1469 named attribute. It does not include attributes inherited from parent
1472 =item B<< $metaclass->get_attribute_map >>
1474 Returns a hash reference representing the attributes defined in this
1475 class. The keys are attribute names and the values are
1476 L<Class::MOP::Attribute> objects.
1478 =item B<< $metaclass->get_attribute_list >>
1480 This will return a list of attributes I<names> for all attributes
1481 defined in this class.
1483 =item B<< $metaclass->get_all_attributes >>
1485 This will traverse the inheritance hierarchy and return a list of all
1486 the L<Class::MOP::Attribute> objects for this class and its parents.
1488 This method can also be called as C<compute_all_applicable_attributes>.
1490 =item B<< $metaclass->find_attribute_by_name($attribute_name) >>
1492 This will return a L<Class::MOP::Attribute> for the specified
1493 C<$attribute_name>. If the class does not have the specified
1494 attribute, it returns C<undef>
1496 Unlike C<get_attribute>, this attribute I<will> look for the named
1497 attribute in superclasses.
1499 =item B<< $metaclass->add_attribute(...) >>
1501 This method accepts either an existing L<Class::MOP::Attribute>
1502 object, or parameters suitable for passing to that class's C<new>
1505 The attribute provided will be added to the class.
1507 Any accessor methods defined by the attribute will be added to the
1508 class when the attribute is added.
1510 If an attribute of the same name already exists, the old attribute
1511 will be removed first.
1513 =item B<< $metaclass->remove_attribute($attribute_name) >>
1515 This will remove the named attribute from the class, and
1516 L<Class::MOP::Attribute> object.
1518 Removing an attribute also removes any accessor methods defined by the
1521 However, note that removing an attribute will only affect I<future>
1522 object instances created for this class, not existing instances.
1524 =item B<< $metaclass->attribute_metaclass >>
1526 Returns the class name of the attribute metaclass for this class. By
1527 default, this is L<Class::MOP::Attribute>. for more information on
1531 =head2 Class Immutability
1533 Making a class immutable "freezes" the class definition. You can no
1534 longer call methods which alter the class, such as adding or removing
1535 methods or attributes.
1537 Making a class immutable lets us optimize the class by inlning some
1538 methods, and also allows us to optimize some methods on the metaclass
1541 The immutabilization system in L<Moose> takes much greater advantage
1542 of the inlining features than Class::MOP itself does.
1546 =item B<< $metaclass->make_immutable(%options) >>
1548 This method will create an immutable transformer and uses it to make
1549 the class and its metaclass object immutable.
1551 Details of how immutabilization works are in L<Class::MOP::Immutable>
1554 =item B<< $metaclass->make_mutable >>
1556 Calling this method reverse the immutabilization transformation.
1558 =item B<< $metaclass->get_immutable_transformer >>
1560 If the class has been made immutable previously, this returns the
1561 L<Class::MOP::Immutable> object that was created to do the
1564 If the class was never made immutable, this method will die.
1568 =head2 Method Modifiers
1570 Method modifiers are hooks which allow a method to be wrapped with
1571 I<before>, I<after> and I<around> method modifiers. Every time a
1572 method is called, it's modifiers are also called.
1574 A class can modify its own methods, as well as methods defined in
1577 =head3 How method modifiers work?
1579 Method modifiers work by wrapping the original method and then
1580 replacing it in the class's symbol table. The wrappers will handle
1581 calling all the modifiers in the appropariate orders and preserving
1582 the calling context for the original method.
1584 The return values of C<before> and C<after> modifiers are
1585 ignored. This is because their purpose is B<not> to filter the input
1586 and output of the primary method (this is done with an I<around>
1589 This may seem like an odd restriction to some, but doing this allows
1590 for simple code to be added at the beginning or end of a method call
1591 without altering the function of the wrapped method or placing any
1592 extra responsibility on the code of the modifier.
1594 Of course if you have more complex needs, you can use the C<around>
1595 modifier which allows you to change both the parameters passed to the
1596 wrapped method, as well as its return value.
1598 Before and around modifiers are called in last-defined-first-called
1599 order, while after modifiers are called in first-defined-first-called
1600 order. So the call tree might looks something like this:
1612 =head3 What is the performance impact?
1614 Of course there is a performance cost associated with method
1615 modifiers, but we have made every effort to make that cost directly
1616 proportional to the number of modifier features you utilize.
1618 The wrapping method does it's best to B<only> do as much work as it
1619 absolutely needs to. In order to do this we have moved some of the
1620 performance costs to set-up time, where they are easier to amortize.
1622 All this said, our benchmarks have indicated the following:
1624 simple wrapper with no modifiers 100% slower
1625 simple wrapper with simple before modifier 400% slower
1626 simple wrapper with simple after modifier 450% slower
1627 simple wrapper with simple around modifier 500-550% slower
1628 simple wrapper with all 3 modifiers 1100% slower
1630 These numbers may seem daunting, but you must remember, every feature
1631 comes with some cost. To put things in perspective, just doing a
1632 simple C<AUTOLOAD> which does nothing but extract the name of the
1633 method called and return it costs about 400% over a normal method
1638 =item B<< $metaclass->add_before_method_modifier($method_name, $code) >>
1640 This wraps the specified method with the supplied subroutine
1641 reference. The modifier will be called as a method itself, and will
1642 receive the same arguments as are passed to the method.
1644 When the modifier exits, the wrapped method will be called.
1646 The return value of the modifier will be ignored.
1648 =item B<< $metaclass->add_after_method_modifier($method_name, $code) >>
1650 This wraps the specified method with the supplied subroutine
1651 reference. The modifier will be called as a method itself, and will
1652 receive the same arguments as are passed to the method.
1654 When the wrapped methods exits, the modifier will be called.
1656 The return value of the modifier will be ignored.
1658 =item B<< $metaclass->add_around_method_modifier($method_name, $code) >>
1660 This wraps the specified method with the supplied subroutine
1663 The first argument passed to the modifier will be a subroutine
1664 reference to the wrapped method. The second argument is the object,
1665 and after that come any arguments passed when the method is called.
1667 The around modifier can choose to call the original method, as well as
1668 what arguments to pass if it does so.
1670 The return value of the modifier is what will be seen by the caller.
1676 Stevan Little E<lt>stevan@iinteractive.comE<gt>
1678 =head1 COPYRIGHT AND LICENSE
1680 Copyright 2006-2009 by Infinity Interactive, Inc.
1682 L<http://www.iinteractive.com>
1684 This library is free software; you can redistribute it and/or modify
1685 it under the same terms as Perl itself.