2 package Class::MOP::Class;
7 use Class::MOP::Immutable;
8 use Class::MOP::Instance;
9 use Class::MOP::Method::Wrapped;
12 use Scalar::Util 'blessed', 'weaken';
14 our $VERSION = '0.78';
15 $VERSION = eval $VERSION;
16 our $AUTHORITY = 'cpan:STEVAN';
18 use base 'Class::MOP::Module';
28 $package_name = shift;
31 $package_name = $options{package};
34 (defined $package_name && $package_name && !ref($package_name))
35 || confess "You must pass a package name and it cannot be blessed";
37 return Class::MOP::get_metaclass_by_name($package_name)
38 || $class->_construct_class_instance(package => $package_name, @_);
41 sub construct_class_instance {
42 warn 'The construct_class_instance method has been made private.'
43 . " The public version is deprecated and will be removed in a future release.\n";
44 goto &_construct_class_instance;
47 # NOTE: (meta-circularity)
48 # this is a special form of &construct_instance
49 # (see below), which is used to construct class
50 # meta-object instances for any Class::MOP::*
51 # class. All other classes will use the more
52 # normal &construct_instance.
53 sub _construct_class_instance {
55 my $options = @_ == 1 ? $_[0] : {@_};
56 my $package_name = $options->{package};
57 (defined $package_name && $package_name)
58 || confess "You must pass a package name";
60 # return the metaclass if we have it cached,
61 # and it is still defined (it has not been
62 # reaped by DESTROY yet, which can happen
63 # annoyingly enough during global destruction)
65 if (defined(my $meta = Class::MOP::get_metaclass_by_name($package_name))) {
70 # we need to deal with the possibility
71 # of class immutability here, and then
72 # get the name of the class appropriately
74 ? ($class->is_immutable
75 ? $class->get_mutable_metaclass_name()
79 # now create the metaclass
81 if ($class eq 'Class::MOP::Class') {
83 $meta = $class->_new($options)
87 # it is safe to use meta here because
88 # class will always be a subclass of
89 # Class::MOP::Class, which defines meta
90 $meta = $class->meta->construct_instance($options)
93 # and check the metaclass compatibility
94 $meta->_check_metaclass_compatibility();
96 Class::MOP::store_metaclass_by_name($package_name, $meta);
99 # we need to weaken any anon classes
100 # so that they can call DESTROY properly
101 Class::MOP::weaken_metaclass($package_name) if $meta->is_anon_class;
108 my $options = @_ == 1 ? $_[0] : {@_};
111 # inherited from Class::MOP::Package
112 'package' => $options->{package},
115 # since the following attributes will
116 # actually be loaded from the symbol
117 # table, and actually bypass the instance
118 # entirely, we can just leave these things
119 # listed here for reference, because they
120 # should not actually have a value associated
122 'namespace' => \undef,
124 # inherited from Class::MOP::Module
126 'authority' => \undef,
128 # defined in Class::MOP::Class
129 'superclasses' => \undef,
133 'attribute_metaclass' => $options->{'attribute_metaclass'}
134 || 'Class::MOP::Attribute',
135 'method_metaclass' => $options->{'method_metaclass'}
136 || 'Class::MOP::Method',
137 'wrapped_method_metaclass' => $options->{'wrapped_method_metaclass'}
138 || 'Class::MOP::Method::Wrapped',
139 'instance_metaclass' => $options->{'instance_metaclass'}
140 || 'Class::MOP::Instance',
144 sub reset_package_cache_flag { (shift)->{'_package_cache_flag'} = undef }
145 sub update_package_cache_flag {
148 # we can manually update the cache number
149 # since we are actually adding the method
150 # to our cache as well. This avoids us
151 # having to regenerate the method_map.
153 $self->{'_package_cache_flag'} = Class::MOP::check_package_cache_flag($self->name);
157 sub check_metaclass_compatibility {
158 warn 'The check_metaclass_compatibility method has been made private.'
159 . " The public version is deprecated and will be removed in a future release.\n";
160 goto &_check_metaclass_compatibility;
163 sub _check_metaclass_compatibility {
166 # this is always okay ...
167 return if ref($self) eq 'Class::MOP::Class' &&
168 $self->instance_metaclass eq 'Class::MOP::Instance';
170 my @class_list = $self->linearized_isa;
171 shift @class_list; # shift off $self->name
173 foreach my $superclass_name (@class_list) {
174 my $super_meta = Class::MOP::get_metaclass_by_name($superclass_name) || next;
177 # we need to deal with the possibility
178 # of class immutability here, and then
179 # get the name of the class appropriately
181 = $super_meta->is_immutable
182 ? $super_meta->get_mutable_metaclass_name()
185 ($self->isa($super_meta_type))
186 || confess $self->name . "->meta => (" . (ref($self)) . ")" .
187 " is not compatible with the " .
188 $superclass_name . "->meta => (" . ($super_meta_type) . ")";
190 # we also need to check that instance metaclasses
191 # are compatibile in the same the class.
192 ($self->instance_metaclass->isa($super_meta->instance_metaclass))
193 || confess $self->name . "->meta->instance_metaclass => (" . ($self->instance_metaclass) . ")" .
194 " is not compatible with the " .
195 $superclass_name . "->meta->instance_metaclass => (" . ($super_meta->instance_metaclass) . ")";
203 # this should be sufficient, if you have a
204 # use case where it is not, write a test and
206 my $ANON_CLASS_SERIAL = 0;
209 # we need a sufficiently annoying prefix
210 # this should suffice for now, this is
211 # used in a couple of places below, so
212 # need to put it up here for now.
213 my $ANON_CLASS_PREFIX = 'Class::MOP::Class::__ANON__::SERIAL::';
217 no warnings 'uninitialized';
218 $self->name =~ /^$ANON_CLASS_PREFIX/;
221 sub create_anon_class {
222 my ($class, %options) = @_;
223 my $package_name = $ANON_CLASS_PREFIX . ++$ANON_CLASS_SERIAL;
224 return $class->create($package_name, %options);
228 # this will only get called for
229 # anon-classes, all other calls
230 # are assumed to occur during
231 # global destruction and so don't
232 # really need to be handled explicitly
236 return if Class::MOP::in_global_destruction(); # it'll happen soon anyway and this just makes things more complicated
238 no warnings 'uninitialized';
239 return unless $self->name =~ /^$ANON_CLASS_PREFIX/;
240 # Moose does a weird thing where it replaces the metaclass for
241 # class when fixing metaclass incompatibility. In that case,
242 # we don't want to clean out the namespace now. We can detect
243 # that because Moose will explicitly update the singleton
244 # cache in Class::MOP.
245 my $current_meta = Class::MOP::get_metaclass_by_name($self->name);
246 return if $current_meta ne $self;
248 my ($serial_id) = ($self->name =~ /^$ANON_CLASS_PREFIX(\d+)/);
250 foreach my $key (keys %{$ANON_CLASS_PREFIX . $serial_id}) {
251 delete ${$ANON_CLASS_PREFIX . $serial_id}{$key};
253 delete ${'main::' . $ANON_CLASS_PREFIX}{$serial_id . '::'};
258 # creating classes with MOP ...
261 my ( $class, @args ) = @_;
263 unshift @args, 'package' if @args % 2 == 1;
265 my (%options) = @args;
266 my $package_name = $options{package};
268 (ref $options{superclasses} eq 'ARRAY')
269 || confess "You must pass an ARRAY ref of superclasses"
270 if exists $options{superclasses};
272 (ref $options{attributes} eq 'ARRAY')
273 || confess "You must pass an ARRAY ref of attributes"
274 if exists $options{attributes};
276 (ref $options{methods} eq 'HASH')
277 || confess "You must pass a HASH ref of methods"
278 if exists $options{methods};
280 $class->SUPER::create(%options);
282 my (%initialize_options) = @args;
283 delete @initialize_options{qw(
291 my $meta = $class->initialize( $package_name => %initialize_options );
294 $meta->add_method('meta' => sub {
295 $class->initialize(ref($_[0]) || $_[0]);
298 $meta->superclasses(@{$options{superclasses}})
299 if exists $options{superclasses};
301 # process attributes first, so that they can
302 # install accessors, but locally defined methods
303 # can then overwrite them. It is maybe a little odd, but
304 # I think this should be the order of things.
305 if (exists $options{attributes}) {
306 foreach my $attr (@{$options{attributes}}) {
307 $meta->add_attribute($attr);
310 if (exists $options{methods}) {
311 foreach my $method_name (keys %{$options{methods}}) {
312 $meta->add_method($method_name, $options{methods}->{$method_name});
321 # all these attribute readers will be bootstrapped
322 # away in the Class::MOP bootstrap section
324 sub get_attribute_map { $_[0]->{'attributes'} }
325 sub attribute_metaclass { $_[0]->{'attribute_metaclass'} }
326 sub method_metaclass { $_[0]->{'method_metaclass'} }
327 sub wrapped_method_metaclass { $_[0]->{'wrapped_method_metaclass'} }
328 sub instance_metaclass { $_[0]->{'instance_metaclass'} }
330 # Instance Construction & Cloning
336 # we need to protect the integrity of the
337 # Class::MOP::Class singletons here, so we
338 # delegate this to &construct_class_instance
339 # which will deal with the singletons
340 return $class->_construct_class_instance(@_)
341 if $class->name->isa('Class::MOP::Class');
342 return $class->construct_instance(@_);
345 sub construct_instance {
347 my $params = @_ == 1 ? $_[0] : {@_};
348 my $meta_instance = $class->get_meta_instance();
349 my $instance = $meta_instance->create_instance();
350 foreach my $attr ($class->compute_all_applicable_attributes()) {
351 $attr->initialize_instance_slot($meta_instance, $instance, $params);
354 # this will only work for a HASH instance type
355 if ($class->is_anon_class) {
356 (Scalar::Util::reftype($instance) eq 'HASH')
357 || confess "Currently only HASH based instances are supported with instance of anon-classes";
359 # At some point we should make this official
360 # as a reserved slot name, but right now I am
361 # going to keep it here.
362 # my $RESERVED_MOP_SLOT = '__MOP__';
363 $instance->{'__MOP__'} = $class;
369 sub get_meta_instance {
371 $self->{'_meta_instance'} ||= $self->create_meta_instance();
374 sub create_meta_instance {
377 my $instance = $self->instance_metaclass->new(
378 associated_metaclass => $self,
379 attributes => [ $self->compute_all_applicable_attributes() ],
382 $self->add_meta_instance_dependencies()
383 if $instance->is_dependent_on_superclasses();
390 my $instance = shift;
391 (blessed($instance) && $instance->isa($class->name))
392 || confess "You must pass an instance of the metaclass (" . (ref $class ? $class->name : $class) . "), not ($instance)";
395 # we need to protect the integrity of the
396 # Class::MOP::Class singletons here, they
397 # should not be cloned.
398 return $instance if $instance->isa('Class::MOP::Class');
399 $class->clone_instance($instance, @_);
403 my ($class, $instance, %params) = @_;
405 || confess "You can only clone instances, ($instance) is not a blessed instance";
406 my $meta_instance = $class->get_meta_instance();
407 my $clone = $meta_instance->clone_instance($instance);
408 foreach my $attr ($class->compute_all_applicable_attributes()) {
409 if ( defined( my $init_arg = $attr->init_arg ) ) {
410 if (exists $params{$init_arg}) {
411 $attr->set_value($clone, $params{$init_arg});
418 sub rebless_instance {
419 my ($self, $instance, %params) = @_;
422 if ($instance->can('meta')) {
423 ($instance->meta->isa('Class::MOP::Class'))
424 || confess 'Cannot rebless instance if ->meta is not an instance of Class::MOP::Class';
425 $old_metaclass = $instance->meta;
428 $old_metaclass = $self->initialize(ref($instance));
431 my $meta_instance = $self->get_meta_instance();
433 $self->name->isa($old_metaclass->name)
434 || confess "You may rebless only into a subclass of (". $old_metaclass->name ."), of which (". $self->name .") isn't.";
437 # we use $_[1] here because of t/306_rebless_overload.t regressions on 5.8.8
438 $meta_instance->rebless_instance_structure($_[1], $self);
440 foreach my $attr ( $self->compute_all_applicable_attributes ) {
441 if ( $attr->has_value($instance) ) {
442 if ( defined( my $init_arg = $attr->init_arg ) ) {
443 $params{$init_arg} = $attr->get_value($instance)
444 unless exists $params{$init_arg};
447 $attr->set_value($instance, $attr->get_value($instance));
452 foreach my $attr ($self->compute_all_applicable_attributes) {
453 $attr->initialize_instance_slot($meta_instance, $instance, \%params);
463 my $var_spec = { sigil => '@', type => 'ARRAY', name => 'ISA' };
466 @{$self->get_package_symbol($var_spec)} = @supers;
469 # on 5.8 and below, we need to call
470 # a method to get Perl to detect
471 # a cycle in the class hierarchy
472 my $class = $self->name;
476 # we need to check the metaclass
477 # compatibility here so that we can
478 # be sure that the superclass is
479 # not potentially creating an issues
480 # we don't know about
482 $self->_check_metaclass_compatibility();
483 $self->update_meta_instance_dependencies();
485 @{$self->get_package_symbol($var_spec)};
491 my $super_class = $self->name;
493 if ( Class::MOP::HAVE_ISAREV() ) {
494 return @{ $super_class->mro::get_isarev() };
498 my $find_derived_classes;
499 $find_derived_classes = sub {
500 my ($outer_class) = @_;
502 my $symbol_table_hashref = do { no strict 'refs'; \%{"${outer_class}::"} };
505 for my $symbol ( keys %$symbol_table_hashref ) {
506 next SYMBOL if $symbol !~ /\A (\w+):: \z/x;
507 my $inner_class = $1;
509 next SYMBOL if $inner_class eq 'SUPER'; # skip '*::SUPER'
513 ? "${outer_class}::$inner_class"
516 if ( $class->isa($super_class) and $class ne $super_class ) {
517 push @derived_classes, $class;
520 next SYMBOL if $class eq 'main'; # skip 'main::*'
522 $find_derived_classes->($class);
526 my $root_class = q{};
527 $find_derived_classes->($root_class);
529 undef $find_derived_classes;
531 @derived_classes = sort { $a->isa($b) ? 1 : $b->isa($a) ? -1 : 0 } @derived_classes;
533 return @derived_classes;
539 return @{ mro::get_linear_isa( (shift)->name ) };
542 sub class_precedence_list {
544 my $name = $self->name;
546 unless (Class::MOP::IS_RUNNING_ON_5_10()) {
548 # We need to check for circular inheritance here
549 # if we are are not on 5.10, cause 5.8 detects it
550 # late. This will do nothing if all is well, and
551 # blow up otherwise. Yes, it's an ugly hack, better
552 # suggestions are welcome.
554 ($name || return)->isa('This is a test for circular inheritance')
557 # if our mro is c3, we can
558 # just grab the linear_isa
559 if (mro::get_mro($name) eq 'c3') {
560 return @{ mro::get_linear_isa($name) }
564 # we can't grab the linear_isa for dfs
565 # since it has all the duplicates
570 $self->initialize($_)->class_precedence_list()
571 } $self->superclasses()
578 sub wrap_method_body {
579 my ( $self, %args ) = @_;
581 ('CODE' eq ref $args{body})
582 || confess "Your code block must be a CODE reference";
584 $self->method_metaclass->wrap(
585 package_name => $self->name,
591 my ($self, $method_name, $method) = @_;
592 (defined $method_name && $method_name)
593 || confess "You must define a method name";
596 if (blessed($method)) {
597 $body = $method->body;
598 if ($method->package_name ne $self->name) {
599 $method = $method->clone(
600 package_name => $self->name,
602 ) if $method->can('clone');
607 $method = $self->wrap_method_body( body => $body, name => $method_name );
610 $method->attach_to_class($self);
612 # This used to call get_method_map, which meant we would build all
613 # the method objects for the class just because we added one
614 # method. This is hackier, but quicker too.
615 $self->{methods}{$method_name} = $method;
617 my $full_method_name = ($self->name . '::' . $method_name);
618 $self->add_package_symbol(
619 { sigil => '&', type => 'CODE', name => $method_name },
620 Class::MOP::subname($full_method_name => $body)
625 my $fetch_and_prepare_method = sub {
626 my ($self, $method_name) = @_;
627 my $wrapped_metaclass = $self->wrapped_method_metaclass;
629 my $method = $self->get_method($method_name);
630 # if we dont have local ...
632 # try to find the next method
633 $method = $self->find_next_method_by_name($method_name);
634 # die if it does not exist
636 || confess "The method '$method_name' was not found in the inheritance hierarchy for " . $self->name;
637 # and now make sure to wrap it
638 # even if it is already wrapped
639 # because we need a new sub ref
640 $method = $wrapped_metaclass->wrap($method);
643 # now make sure we wrap it properly
644 $method = $wrapped_metaclass->wrap($method)
645 unless $method->isa($wrapped_metaclass);
647 $self->add_method($method_name => $method);
651 sub add_before_method_modifier {
652 my ($self, $method_name, $method_modifier) = @_;
653 (defined $method_name && $method_name)
654 || confess "You must pass in a method name";
655 my $method = $fetch_and_prepare_method->($self, $method_name);
656 $method->add_before_modifier(
657 Class::MOP::subname(':before' => $method_modifier)
661 sub add_after_method_modifier {
662 my ($self, $method_name, $method_modifier) = @_;
663 (defined $method_name && $method_name)
664 || confess "You must pass in a method name";
665 my $method = $fetch_and_prepare_method->($self, $method_name);
666 $method->add_after_modifier(
667 Class::MOP::subname(':after' => $method_modifier)
671 sub add_around_method_modifier {
672 my ($self, $method_name, $method_modifier) = @_;
673 (defined $method_name && $method_name)
674 || confess "You must pass in a method name";
675 my $method = $fetch_and_prepare_method->($self, $method_name);
676 $method->add_around_modifier(
677 Class::MOP::subname(':around' => $method_modifier)
682 # the methods above used to be named like this:
683 # ${pkg}::${method}:(before|after|around)
684 # but this proved problematic when using one modifier
685 # to wrap multiple methods (something which is likely
686 # to happen pretty regularly IMO). So instead of naming
687 # it like this, I have chosen to just name them purely
688 # with their modifier names, like so:
689 # :(before|after|around)
690 # The fact is that in a stack trace, it will be fairly
691 # evident from the context what method they are attached
692 # to, and so don't need the fully qualified name.
698 $self->add_method(@_);
702 my ($self, $method_name) = @_;
703 (defined $method_name && $method_name)
704 || confess "You must define a method name";
706 exists $self->{methods}{$method_name} || exists $self->get_method_map->{$method_name};
710 my ($self, $method_name) = @_;
711 (defined $method_name && $method_name)
712 || confess "You must define a method name";
714 return $self->{methods}{$method_name} || $self->get_method_map->{$method_name};
718 my ($self, $method_name) = @_;
719 (defined $method_name && $method_name)
720 || confess "You must define a method name";
722 my $removed_method = delete $self->get_method_map->{$method_name};
724 $self->remove_package_symbol(
725 { sigil => '&', type => 'CODE', name => $method_name }
728 $removed_method->detach_from_class if $removed_method;
730 $self->update_package_cache_flag; # still valid, since we just removed the method from the map
732 return $removed_method;
735 sub get_method_list {
737 keys %{$self->get_method_map};
740 sub find_method_by_name {
741 my ($self, $method_name) = @_;
742 (defined $method_name && $method_name)
743 || confess "You must define a method name to find";
744 foreach my $class ($self->linearized_isa) {
745 # fetch the meta-class ...
746 my $meta = $self->initialize($class);
747 return $meta->get_method($method_name)
748 if $meta->has_method($method_name);
753 sub get_all_methods {
755 my %methods = map { %{ $self->initialize($_)->get_method_map } } reverse $self->linearized_isa;
756 return values %methods;
760 sub compute_all_applicable_methods {
764 class => $_->package_name,
765 code => $_, # sigh, overloading
767 } shift->get_all_methods(@_);
770 sub get_all_method_names {
773 grep { $uniq{$_}++ == 0 } map { $_->name } $self->get_all_methods;
776 sub find_all_methods_by_name {
777 my ($self, $method_name) = @_;
778 (defined $method_name && $method_name)
779 || confess "You must define a method name to find";
781 foreach my $class ($self->linearized_isa) {
782 # fetch the meta-class ...
783 my $meta = $self->initialize($class);
785 name => $method_name,
787 code => $meta->get_method($method_name)
788 } if $meta->has_method($method_name);
793 sub find_next_method_by_name {
794 my ($self, $method_name) = @_;
795 (defined $method_name && $method_name)
796 || confess "You must define a method name to find";
797 my @cpl = $self->linearized_isa;
798 shift @cpl; # discard ourselves
799 foreach my $class (@cpl) {
800 # fetch the meta-class ...
801 my $meta = $self->initialize($class);
802 return $meta->get_method($method_name)
803 if $meta->has_method($method_name);
812 # either we have an attribute object already
813 # or we need to create one from the args provided
814 my $attribute = blessed($_[0]) ? $_[0] : $self->attribute_metaclass->new(@_);
815 # make sure it is derived from the correct type though
816 ($attribute->isa('Class::MOP::Attribute'))
817 || confess "Your attribute must be an instance of Class::MOP::Attribute (or a subclass)";
819 # first we attach our new attribute
820 # because it might need certain information
821 # about the class which it is attached to
822 $attribute->attach_to_class($self);
824 # then we remove attributes of a conflicting
825 # name here so that we can properly detach
826 # the old attr object, and remove any
827 # accessors it would have generated
828 if ( $self->has_attribute($attribute->name) ) {
829 $self->remove_attribute($attribute->name);
831 $self->invalidate_meta_instances();
834 # then onto installing the new accessors
835 $self->get_attribute_map->{$attribute->name} = $attribute;
837 # invalidate package flag here
838 my $e = do { local $@; eval { $attribute->install_accessors() }; $@ };
840 $self->remove_attribute($attribute->name);
847 sub update_meta_instance_dependencies {
850 if ( $self->{meta_instance_dependencies} ) {
851 return $self->add_meta_instance_dependencies;
855 sub add_meta_instance_dependencies {
858 $self->remove_meta_instance_dependencies;
860 my @attrs = $self->compute_all_applicable_attributes();
863 my @classes = grep { not $seen{$_->name}++ } map { $_->associated_class } @attrs;
865 foreach my $class ( @classes ) {
866 $class->add_dependent_meta_instance($self);
869 $self->{meta_instance_dependencies} = \@classes;
872 sub remove_meta_instance_dependencies {
875 if ( my $classes = delete $self->{meta_instance_dependencies} ) {
876 foreach my $class ( @$classes ) {
877 $class->remove_dependent_meta_instance($self);
887 sub add_dependent_meta_instance {
888 my ( $self, $metaclass ) = @_;
889 push @{ $self->{dependent_meta_instances} }, $metaclass;
892 sub remove_dependent_meta_instance {
893 my ( $self, $metaclass ) = @_;
894 my $name = $metaclass->name;
895 @$_ = grep { $_->name ne $name } @$_ for $self->{dependent_meta_instances};
898 sub invalidate_meta_instances {
900 $_->invalidate_meta_instance() for $self, @{ $self->{dependent_meta_instances} };
903 sub invalidate_meta_instance {
905 undef $self->{_meta_instance};
909 my ($self, $attribute_name) = @_;
910 (defined $attribute_name && $attribute_name)
911 || confess "You must define an attribute name";
912 exists $self->get_attribute_map->{$attribute_name};
916 my ($self, $attribute_name) = @_;
917 (defined $attribute_name && $attribute_name)
918 || confess "You must define an attribute name";
919 return $self->get_attribute_map->{$attribute_name}
921 # this will return undef anyway, so no need ...
922 # if $self->has_attribute($attribute_name);
926 sub remove_attribute {
927 my ($self, $attribute_name) = @_;
928 (defined $attribute_name && $attribute_name)
929 || confess "You must define an attribute name";
930 my $removed_attribute = $self->get_attribute_map->{$attribute_name};
931 return unless defined $removed_attribute;
932 delete $self->get_attribute_map->{$attribute_name};
933 $self->invalidate_meta_instances();
934 $removed_attribute->remove_accessors();
935 $removed_attribute->detach_from_class();
936 return $removed_attribute;
939 sub get_attribute_list {
941 keys %{$self->get_attribute_map};
944 sub get_all_attributes {
945 shift->compute_all_applicable_attributes(@_);
948 sub compute_all_applicable_attributes {
950 my %attrs = map { %{ $self->initialize($_)->get_attribute_map } } reverse $self->linearized_isa;
951 return values %attrs;
954 sub find_attribute_by_name {
955 my ($self, $attr_name) = @_;
956 foreach my $class ($self->linearized_isa) {
957 # fetch the meta-class ...
958 my $meta = $self->initialize($class);
959 return $meta->get_attribute($attr_name)
960 if $meta->has_attribute($attr_name);
965 # check if we can reinitialize
969 # if any local attr is defined
970 return if $self->get_attribute_list;
972 # or any non-declared methods
973 if ( my @methods = values %{ $self->get_method_map } ) {
974 my $metaclass = $self->method_metaclass;
975 foreach my $method ( @methods ) {
976 return if $method->isa("Class::MOP::Method::Generated");
977 # FIXME do we need to enforce this too? return unless $method->isa($metaclass);
987 sub is_immutable { 0 }
990 # Why I changed this (groditi)
991 # - One Metaclass may have many Classes through many Metaclass instances
992 # - One Metaclass should only have one Immutable Transformer instance
993 # - Each Class may have different Immutabilizing options
994 # - Therefore each Metaclass instance may have different Immutabilizing options
995 # - We need to store one Immutable Transformer instance per Metaclass
996 # - We need to store one set of Immutable Transformer options per Class
997 # - Upon make_mutable we may delete the Immutabilizing options
998 # - We could clean the immutable Transformer instance when there is no more
999 # immutable Classes of that type, but we can also keep it in case
1000 # another class with this same Metaclass becomes immutable. It is a case
1001 # of trading of storing an instance to avoid unnecessary instantiations of
1002 # Immutable Transformers. You may view this as a memory leak, however
1003 # Because we have few Metaclasses, in practice it seems acceptable
1004 # - To allow Immutable Transformers instances to be cleaned up we could weaken
1005 # the reference stored in $IMMUTABLE_TRANSFORMERS{$class} and ||= should DWIM
1009 my %IMMUTABLE_TRANSFORMERS;
1010 my %IMMUTABLE_OPTIONS;
1012 sub get_immutable_options {
1014 return if $self->is_mutable;
1015 confess "unable to find immutabilizing options"
1016 unless exists $IMMUTABLE_OPTIONS{$self->name};
1017 my %options = %{$IMMUTABLE_OPTIONS{$self->name}};
1018 delete $options{IMMUTABLE_TRANSFORMER};
1022 sub get_immutable_transformer {
1024 if( $self->is_mutable ){
1025 return $IMMUTABLE_TRANSFORMERS{$self->name} ||= $self->create_immutable_transformer;
1027 confess "unable to find transformer for immutable class"
1028 unless exists $IMMUTABLE_OPTIONS{$self->name};
1029 return $IMMUTABLE_OPTIONS{$self->name}->{IMMUTABLE_TRANSFORMER};
1032 sub make_immutable {
1036 my $transformer = $self->get_immutable_transformer;
1037 $transformer->make_metaclass_immutable($self, \%options);
1038 $IMMUTABLE_OPTIONS{$self->name} =
1039 { %options, IMMUTABLE_TRANSFORMER => $transformer };
1041 if( exists $options{debug} && $options{debug} ){
1042 print STDERR "# of Metaclass options: ", keys %IMMUTABLE_OPTIONS;
1043 print STDERR "# of Immutable transformers: ", keys %IMMUTABLE_TRANSFORMERS;
1051 return if $self->is_mutable;
1052 my $options = delete $IMMUTABLE_OPTIONS{$self->name};
1053 confess "unable to find immutabilizing options" unless ref $options;
1054 my $transformer = delete $options->{IMMUTABLE_TRANSFORMER};
1055 $transformer->make_metaclass_mutable($self, $options);
1060 sub create_immutable_transformer {
1062 my $class = Class::MOP::Immutable->new($self, {
1063 read_only => [qw/superclasses/],
1070 remove_package_symbol
1073 class_precedence_list => 'ARRAY',
1074 linearized_isa => 'ARRAY', # FIXME perl 5.10 memoizes this on its own, no need?
1075 get_all_methods => 'ARRAY',
1076 get_all_method_names => 'ARRAY',
1077 #get_all_attributes => 'ARRAY', # it's an alias, no need, but maybe in the future
1078 compute_all_applicable_attributes => 'ARRAY',
1079 get_meta_instance => 'SCALAR',
1080 get_method_map => 'SCALAR',
1083 # this is ugly, but so are typeglobs,
1084 # so whattayahgonnadoboutit
1087 add_package_symbol => sub {
1088 my $original = shift;
1089 confess "Cannot add package symbols to an immutable metaclass"
1090 unless (caller(2))[3] eq 'Class::MOP::Package::get_package_symbol';
1092 # This is a workaround for a bug in 5.8.1 which thinks that
1093 # goto $original->body
1094 # is trying to go to a label
1095 my $body = $original->body;
1111 Class::MOP::Class - Class Meta Object
1115 # assuming that class Foo
1116 # has been defined, you can
1118 # use this for introspection ...
1120 # add a method to Foo ...
1121 Foo->meta->add_method( 'bar' => sub {...} )
1123 # get a list of all the classes searched
1124 # the method dispatcher in the correct order
1125 Foo->meta->class_precedence_list()
1127 # remove a method from Foo
1128 Foo->meta->remove_method('bar');
1130 # or use this to actually create classes ...
1132 Class::MOP::Class->create(
1135 superclasses => ['Foo'],
1137 Class::MOP:: : Attribute->new('$bar'),
1138 Class::MOP:: : Attribute->new('$baz'),
1141 calculate_bar => sub {...},
1142 construct_baz => sub {...}
1149 This is the largest and most complex part of the Class::MOP
1150 meta-object protocol. It controls the introspection and manipulation
1151 of Perl 5 classes, and it can create them as wlel. The best way to
1152 understand what this module can do, is to read the documentation for
1153 each of its methods.
1157 C<Class::MOP::Class> is a subclass of L<Class::MOP::Module>.
1161 =head2 Class construction
1163 These methods all create new C<Class::MOP::Class> objects. These
1164 objects can represent existing classes, or they can be used to create
1165 new classes from scratch.
1167 The metaclass object for a given class is a singleton. If you attempt
1168 to create a metaclass for the same class twice, you will just get the
1173 =item B<< Class::MOP::Class->create($package_name, %options) >>
1175 This method creates a new C<Class::MOP::Class> object with the given
1176 package name. It accepts a number of options.
1182 An optional version number for the newly created package.
1186 An optional authority for the newly created package.
1188 =item * superclasses
1190 An optional array reference of superclass names.
1194 An optional hash reference of methods for the class. The keys of the
1195 hash reference are method names, and values are subroutine references.
1199 An optional array reference of attributes.
1201 An attribute can be passed as an existing L<Class::MOP::Attribute>
1202 object, I<or> or as a hash reference of options which will be passed
1203 to the attribute metaclass's constructor.
1207 =item B<< Class::MOP::Class->create_anon_class(%options) >>
1209 This method works just like C<< Class::MOP::Class->create >> but it
1210 creates an "anonymous" class. In fact, the class does have a name, but
1211 that name is a unique name generated internally by this module.
1213 It accepts the same C<superclasses>, C<methods>, and C<attributes>
1214 parameters that C<create> accepts.
1216 Anonymous classes are destroyed once the metaclass they are attached
1217 to goes out of scope, and will be removed from Perl's internal symbol
1220 All instances of an anonymous class keep a special reference to the
1221 metaclass object, which prevents the metaclass from going out of scope
1222 while any instances exist.
1224 This only works if the instance if based on a hash reference, however.
1226 =item B<< Class::MOP::Class->initialize($package_name, %options) >>
1228 This method will initialize a C<Class::MOP::Class> object for the
1229 named package. Unlike C<create>, this method I<will not> create a new
1232 The purpose of this method is to retrieve a C<Class::MOP::Class>
1233 object for introspecting an existing class.
1235 If an existing C<Class::MOP::Class> object exists for the named
1236 package, it will be returned, and any options provided will be
1239 If the object does not yet exist, it will be created.
1241 The valid options that can be passed to this method are
1242 C<attribute_metaclass>, C<method_metaclass>,
1243 C<wrapped_method_metaclass>, and C<instance_metaclass>. These are all
1244 optional, and default to the appropriate class in the C<Class::MOP>
1249 =head2 Object instance construction and cloning
1251 These methods are all related to creating and/or cloning object
1256 =item B<< $metaclass->clone_object($instance, %params) >>
1258 This method clones an existing object instance. Any parameters you
1259 provide are will override existing attribute values in the object.
1261 This is a convience method for cloning an object instance, then
1262 blessing it into the appropriate package.
1264 You could implement a clone method in your class, using this method:
1267 my ($self, %params) = @_;
1268 $self->meta->clone_object($self, %params);
1271 =item B<< $metaclass->rebless_instance($instance, %params) >>
1273 This method changes the class of C<$instance> to the metaclass's class.
1275 You can only rebless an instance into a subclass of its current
1276 class. If you pass any additional parameters, these will be treated
1277 like constructor parameters and used to initialize the object's
1278 attributes. Any existing attributes that are already set will be
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.
1458 =head2 Attribute introspection and creation
1460 Because Perl 5 does not have a core concept of attributes in classes,
1461 we can only return information about attributes which have been added
1462 via this class's methods. We cannot discover information about
1463 attributes which are defined in terms of "regular" Perl 5 methods.
1467 =item B<< $metaclass->get_attribute($attribute_name) >>
1469 This will return a L<Class::MOP::Attribute> for the specified
1470 C<$attribute_name>. If the class does not have the specified
1471 attribute, it returns C<undef>
1473 =item B<< $metaclass->has_attribute($attribute_name) >>
1475 Returns a boolean indicating whether or not the class defines the
1476 named attribute. It does not include attributes inherited from parent
1479 =item B<< $metaclass->get_attribute_map >>
1481 Returns a hash reference representing the attributes defined in this
1482 class. The keys are attribute names and the values are
1483 L<Class::MOP::Attribute> objects.
1485 =item B<< $metaclass->get_attribute_list >>
1487 This will return a list of attributes I<names> for all attributes
1488 defined in this class.
1490 =item B<< $metaclass->get_all_attributes >>
1492 This will traverse the inheritance hierarchy and return a list of all
1493 the L<Class::MOP::Attribute> objects for this class and its parents.
1495 This method can also be called as C<compute_all_applicable_attributes>.
1497 =item B<< $metaclass->find_attribute_by_name($attribute_name) >>
1499 This will return a L<Class::MOP::Attribute> for the specified
1500 C<$attribute_name>. If the class does not have the specified
1501 attribute, it returns C<undef>
1503 Unlike C<get_attribute>, this attribute I<will> look for the named
1504 attribute in superclasses.
1506 =item B<< $metaclass->add_attribute(...) >>
1508 This method accepts either an existing L<Class::MOP::Attribute>
1509 object, or parameters suitable for passing to that class's C<new>
1512 The attribute provided will be added to the class.
1514 Any accessor methods defined by the attribute will be added to the
1515 class when the attribute is added.
1517 If an attribute of the same name already exists, the old attribute
1518 will be removed first.
1520 =item B<< $metaclass->remove_attribute($attribute_name) >>
1522 This will remove the named attribute from the class, and
1523 L<Class::MOP::Attribute> object.
1525 Removing an attribute also removes any accessor methods defined by the
1528 However, note that removing an attribute will only affect I<future>
1529 object instances created for this class, not existing instances.
1531 =item B<< $metaclass->attribute_metaclass >>
1533 Returns the class name of the attribute metaclass for this class. By
1534 default, this is L<Class::MOP::Attribute>. for more information on
1538 =head2 Class Immutability
1540 Making a class immutable "freezes" the class definition. You can no
1541 longer call methods which alter the class, such as adding or removing
1542 methods or attributes.
1544 Making a class immutable lets us optimize the class by inlning some
1545 methods, and also allows us to optimize some methods on the metaclass
1548 The immutabilization system in L<Moose> takes much greater advantage
1549 of the inlining features than Class::MOP itself does.
1553 =item B<< $metaclass->make_immutable(%options) >>
1555 This method will create an immutable transformer and uses it to make
1556 the class and its metaclass object immutable.
1558 Details of how immutabilization works are in L<Class::MOP::Immutable>
1561 =item B<< $metaclass->make_mutable >>
1563 Calling this method reverse the immutabilization transformation.
1565 =item B<< $metaclass->get_immutable_transformer >>
1567 If the class has been made immutable previously, this returns the
1568 L<Class::MOP::Immutable> object that was created to do the
1571 If the class was never made immutable, this method will die.
1575 =head2 Method Modifiers
1577 Method modifiers are hooks which allow a method to be wrapped with
1578 I<before>, I<after> and I<around> method modifiers. Every time a
1579 method is called, it's modifiers are also called.
1581 A class can modify its own methods, as well as methods defined in
1584 =head3 How method modifiers work?
1586 Method modifiers work by wrapping the original method and then
1587 replacing it in the class's symbol table. The wrappers will handle
1588 calling all the modifiers in the appropariate orders and preserving
1589 the calling context for the original method.
1591 The return values of C<before> and C<after> modifiers are
1592 ignored. This is because their purpose is B<not> to filter the input
1593 and output of the primary method (this is done with an I<around>
1596 This may seem like an odd restriction to some, but doing this allows
1597 for simple code to be added at the beginning or end of a method call
1598 without altering the function of the wrapped method or placing any
1599 extra responsibility on the code of the modifier.
1601 Of course if you have more complex needs, you can use the C<around>
1602 modifier which allows you to change both the parameters passed to the
1603 wrapped method, as well as its return value.
1605 Before and around modifiers are called in last-defined-first-called
1606 order, while after modifiers are called in first-defined-first-called
1607 order. So the call tree might looks something like this:
1619 =head3 What is the performance impact?
1621 Of course there is a performance cost associated with method
1622 modifiers, but we have made every effort to make that cost directly
1623 proportional to the number of modifier features you utilize.
1625 The wrapping method does it's best to B<only> do as much work as it
1626 absolutely needs to. In order to do this we have moved some of the
1627 performance costs to set-up time, where they are easier to amortize.
1629 All this said, our benchmarks have indicated the following:
1631 simple wrapper with no modifiers 100% slower
1632 simple wrapper with simple before modifier 400% slower
1633 simple wrapper with simple after modifier 450% slower
1634 simple wrapper with simple around modifier 500-550% slower
1635 simple wrapper with all 3 modifiers 1100% slower
1637 These numbers may seem daunting, but you must remember, every feature
1638 comes with some cost. To put things in perspective, just doing a
1639 simple C<AUTOLOAD> which does nothing but extract the name of the
1640 method called and return it costs about 400% over a normal method
1645 =item B<< $metaclass->add_before_method_modifier($method_name, $code) >>
1647 This wraps the specified method with the supplied subroutine
1648 reference. The modifier will be called as a method itself, and will
1649 receive the same arguments as are passed to the method.
1651 When the modifier exits, the wrapped method will be called.
1653 The return value of the modifier will be ignored.
1655 =item B<< $metaclass->add_after_method_modifier($method_name, $code) >>
1657 This wraps the specified method with the supplied subroutine
1658 reference. The modifier will be called as a method itself, and will
1659 receive the same arguments as are passed to the method.
1661 When the wrapped methods exits, the modifier will be called.
1663 The return value of the modifier will be ignored.
1665 =item B<< $metaclass->add_around_method_modifier($method_name, $code) >>
1667 This wraps the specified method with the supplied subroutine
1670 The first argument passed to the modifier will be a subroutine
1671 reference to the wrapped method. The second argument is the object,
1672 and after that come any arguments passed when the method is called.
1674 The around modifier can choose to call the original method, as well as
1675 what arguments to pass if it does so.
1677 The return value of the modifier is what will be seen by the caller.
1683 Stevan Little E<lt>stevan@iinteractive.comE<gt>
1685 =head1 COPYRIGHT AND LICENSE
1687 Copyright 2006-2009 by Infinity Interactive, Inc.
1689 L<http://www.iinteractive.com>
1691 This library is free software; you can redistribute it and/or modify
1692 it under the same terms as Perl itself.