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 # NOTE: (meta-circularity)
42 # this is a special form of &construct_instance
43 # (see below), which is used to construct class
44 # meta-object instances for any Class::MOP::*
45 # class. All other classes will use the more
46 # normal &construct_instance.
47 sub construct_class_instance {
49 my $options = @_ == 1 ? $_[0] : {@_};
50 my $package_name = $options->{package};
51 (defined $package_name && $package_name)
52 || confess "You must pass a package name";
54 # return the metaclass if we have it cached,
55 # and it is still defined (it has not been
56 # reaped by DESTROY yet, which can happen
57 # annoyingly enough during global destruction)
59 if (defined(my $meta = Class::MOP::get_metaclass_by_name($package_name))) {
64 # we need to deal with the possibility
65 # of class immutability here, and then
66 # get the name of the class appropriately
68 ? ($class->is_immutable
69 ? $class->get_mutable_metaclass_name()
73 # now create the metaclass
75 if ($class eq 'Class::MOP::Class') {
77 $meta = $class->_new($options)
81 # it is safe to use meta here because
82 # class will always be a subclass of
83 # Class::MOP::Class, which defines meta
84 $meta = $class->meta->construct_instance($options)
87 # and check the metaclass compatibility
88 $meta->check_metaclass_compatibility();
90 Class::MOP::store_metaclass_by_name($package_name, $meta);
93 # we need to weaken any anon classes
94 # so that they can call DESTROY properly
95 Class::MOP::weaken_metaclass($package_name) if $meta->is_anon_class;
102 my $options = @_ == 1 ? $_[0] : {@_};
105 # inherited from Class::MOP::Package
106 'package' => $options->{package},
109 # since the following attributes will
110 # actually be loaded from the symbol
111 # table, and actually bypass the instance
112 # entirely, we can just leave these things
113 # listed here for reference, because they
114 # should not actually have a value associated
116 'namespace' => \undef,
118 # inherited from Class::MOP::Module
120 'authority' => \undef,
122 # defined in Class::MOP::Class
123 'superclasses' => \undef,
127 'attribute_metaclass' => $options->{'attribute_metaclass'}
128 || 'Class::MOP::Attribute',
129 'method_metaclass' => $options->{'method_metaclass'}
130 || 'Class::MOP::Method',
131 'wrapped_method_metaclass' => $options->{'wrapped_method_metaclass'}
132 || 'Class::MOP::Method::Wrapped',
133 'instance_metaclass' => $options->{'instance_metaclass'}
134 || 'Class::MOP::Instance',
138 sub reset_package_cache_flag { (shift)->{'_package_cache_flag'} = undef }
139 sub update_package_cache_flag {
142 # we can manually update the cache number
143 # since we are actually adding the method
144 # to our cache as well. This avoids us
145 # having to regenerate the method_map.
147 $self->{'_package_cache_flag'} = Class::MOP::check_package_cache_flag($self->name);
150 sub check_metaclass_compatibility {
153 # this is always okay ...
154 return if ref($self) eq 'Class::MOP::Class' &&
155 $self->instance_metaclass eq 'Class::MOP::Instance';
157 my @class_list = $self->linearized_isa;
158 shift @class_list; # shift off $self->name
160 foreach my $superclass_name (@class_list) {
161 my $super_meta = Class::MOP::get_metaclass_by_name($superclass_name) || next;
164 # we need to deal with the possibility
165 # of class immutability here, and then
166 # get the name of the class appropriately
168 = $super_meta->is_immutable
169 ? $super_meta->get_mutable_metaclass_name()
172 ($self->isa($super_meta_type))
173 || confess $self->name . "->meta => (" . (ref($self)) . ")" .
174 " is not compatible with the " .
175 $superclass_name . "->meta => (" . ($super_meta_type) . ")";
177 # we also need to check that instance metaclasses
178 # are compatibile in the same the class.
179 ($self->instance_metaclass->isa($super_meta->instance_metaclass))
180 || confess $self->name . "->meta->instance_metaclass => (" . ($self->instance_metaclass) . ")" .
181 " is not compatible with the " .
182 $superclass_name . "->meta->instance_metaclass => (" . ($super_meta->instance_metaclass) . ")";
190 # this should be sufficient, if you have a
191 # use case where it is not, write a test and
193 my $ANON_CLASS_SERIAL = 0;
196 # we need a sufficiently annoying prefix
197 # this should suffice for now, this is
198 # used in a couple of places below, so
199 # need to put it up here for now.
200 my $ANON_CLASS_PREFIX = 'Class::MOP::Class::__ANON__::SERIAL::';
204 no warnings 'uninitialized';
205 $self->name =~ /^$ANON_CLASS_PREFIX/;
208 sub create_anon_class {
209 my ($class, %options) = @_;
210 my $package_name = $ANON_CLASS_PREFIX . ++$ANON_CLASS_SERIAL;
211 return $class->create($package_name, %options);
215 # this will only get called for
216 # anon-classes, all other calls
217 # are assumed to occur during
218 # global destruction and so don't
219 # really need to be handled explicitly
223 return if Class::MOP::in_global_destruction(); # it'll happen soon anyway and this just makes things more complicated
225 no warnings 'uninitialized';
226 return unless $self->name =~ /^$ANON_CLASS_PREFIX/;
227 # Moose does a weird thing where it replaces the metaclass for
228 # class when fixing metaclass incompatibility. In that case,
229 # we don't want to clean out the namespace now. We can detect
230 # that because Moose will explicitly update the singleton
231 # cache in Class::MOP.
232 my $current_meta = Class::MOP::get_metaclass_by_name($self->name);
233 return if $current_meta ne $self;
235 my ($serial_id) = ($self->name =~ /^$ANON_CLASS_PREFIX(\d+)/);
237 foreach my $key (keys %{$ANON_CLASS_PREFIX . $serial_id}) {
238 delete ${$ANON_CLASS_PREFIX . $serial_id}{$key};
240 delete ${'main::' . $ANON_CLASS_PREFIX}{$serial_id . '::'};
245 # creating classes with MOP ...
248 my ( $class, @args ) = @_;
250 unshift @args, 'package' if @args % 2 == 1;
252 my (%options) = @args;
253 my $package_name = $options{package};
255 (ref $options{superclasses} eq 'ARRAY')
256 || confess "You must pass an ARRAY ref of superclasses"
257 if exists $options{superclasses};
259 (ref $options{attributes} eq 'ARRAY')
260 || confess "You must pass an ARRAY ref of attributes"
261 if exists $options{attributes};
263 (ref $options{methods} eq 'HASH')
264 || confess "You must pass a HASH ref of methods"
265 if exists $options{methods};
267 $class->SUPER::create(%options);
269 my (%initialize_options) = @args;
270 delete @initialize_options{qw(
278 my $meta = $class->initialize( $package_name => %initialize_options );
281 $meta->add_method('meta' => sub {
282 $class->initialize(ref($_[0]) || $_[0]);
285 $meta->superclasses(@{$options{superclasses}})
286 if exists $options{superclasses};
288 # process attributes first, so that they can
289 # install accessors, but locally defined methods
290 # can then overwrite them. It is maybe a little odd, but
291 # I think this should be the order of things.
292 if (exists $options{attributes}) {
293 foreach my $attr (@{$options{attributes}}) {
294 $meta->add_attribute($attr);
297 if (exists $options{methods}) {
298 foreach my $method_name (keys %{$options{methods}}) {
299 $meta->add_method($method_name, $options{methods}->{$method_name});
308 # all these attribute readers will be bootstrapped
309 # away in the Class::MOP bootstrap section
311 sub get_attribute_map { $_[0]->{'attributes'} }
312 sub attribute_metaclass { $_[0]->{'attribute_metaclass'} }
313 sub method_metaclass { $_[0]->{'method_metaclass'} }
314 sub wrapped_method_metaclass { $_[0]->{'wrapped_method_metaclass'} }
315 sub instance_metaclass { $_[0]->{'instance_metaclass'} }
317 # Instance Construction & Cloning
323 # we need to protect the integrity of the
324 # Class::MOP::Class singletons here, so we
325 # delegate this to &construct_class_instance
326 # which will deal with the singletons
327 return $class->construct_class_instance(@_)
328 if $class->name->isa('Class::MOP::Class');
329 return $class->construct_instance(@_);
332 sub construct_instance {
334 my $params = @_ == 1 ? $_[0] : {@_};
335 my $meta_instance = $class->get_meta_instance();
336 my $instance = $meta_instance->create_instance();
337 foreach my $attr ($class->compute_all_applicable_attributes()) {
338 $attr->initialize_instance_slot($meta_instance, $instance, $params);
341 # this will only work for a HASH instance type
342 if ($class->is_anon_class) {
343 (Scalar::Util::reftype($instance) eq 'HASH')
344 || confess "Currently only HASH based instances are supported with instance of anon-classes";
346 # At some point we should make this official
347 # as a reserved slot name, but right now I am
348 # going to keep it here.
349 # my $RESERVED_MOP_SLOT = '__MOP__';
350 $instance->{'__MOP__'} = $class;
356 sub get_meta_instance {
358 $self->{'_meta_instance'} ||= $self->create_meta_instance();
361 sub create_meta_instance {
364 my $instance = $self->instance_metaclass->new(
365 associated_metaclass => $self,
366 attributes => [ $self->compute_all_applicable_attributes() ],
369 $self->add_meta_instance_dependencies()
370 if $instance->is_dependent_on_superclasses();
377 my $instance = shift;
378 (blessed($instance) && $instance->isa($class->name))
379 || confess "You must pass an instance of the metaclass (" . (ref $class ? $class->name : $class) . "), not ($instance)";
382 # we need to protect the integrity of the
383 # Class::MOP::Class singletons here, they
384 # should not be cloned.
385 return $instance if $instance->isa('Class::MOP::Class');
386 $class->clone_instance($instance, @_);
390 my ($class, $instance, %params) = @_;
392 || confess "You can only clone instances, ($instance) is not a blessed instance";
393 my $meta_instance = $class->get_meta_instance();
394 my $clone = $meta_instance->clone_instance($instance);
395 foreach my $attr ($class->compute_all_applicable_attributes()) {
396 if ( defined( my $init_arg = $attr->init_arg ) ) {
397 if (exists $params{$init_arg}) {
398 $attr->set_value($clone, $params{$init_arg});
405 sub rebless_instance {
406 my ($self, $instance, %params) = @_;
409 if ($instance->can('meta')) {
410 ($instance->meta->isa('Class::MOP::Class'))
411 || confess 'Cannot rebless instance if ->meta is not an instance of Class::MOP::Class';
412 $old_metaclass = $instance->meta;
415 $old_metaclass = $self->initialize(ref($instance));
418 my $meta_instance = $self->get_meta_instance();
420 $self->name->isa($old_metaclass->name)
421 || confess "You may rebless only into a subclass of (". $old_metaclass->name ."), of which (". $self->name .") isn't.";
424 # we use $_[1] here because of t/306_rebless_overload.t regressions on 5.8.8
425 $meta_instance->rebless_instance_structure($_[1], $self);
427 foreach my $attr ( $self->compute_all_applicable_attributes ) {
428 if ( $attr->has_value($instance) ) {
429 if ( defined( my $init_arg = $attr->init_arg ) ) {
430 $params{$init_arg} = $attr->get_value($instance)
431 unless exists $params{$init_arg};
434 $attr->set_value($instance, $attr->get_value($instance));
439 foreach my $attr ($self->compute_all_applicable_attributes) {
440 $attr->initialize_instance_slot($meta_instance, $instance, \%params);
450 my $var_spec = { sigil => '@', type => 'ARRAY', name => 'ISA' };
453 @{$self->get_package_symbol($var_spec)} = @supers;
456 # on 5.8 and below, we need to call
457 # a method to get Perl to detect
458 # a cycle in the class hierarchy
459 my $class = $self->name;
463 # we need to check the metaclass
464 # compatibility here so that we can
465 # be sure that the superclass is
466 # not potentially creating an issues
467 # we don't know about
469 $self->check_metaclass_compatibility();
470 $self->update_meta_instance_dependencies();
472 @{$self->get_package_symbol($var_spec)};
478 my $super_class = $self->name;
480 if ( Class::MOP::HAVE_ISAREV() ) {
481 return @{ $super_class->mro::get_isarev() };
485 my $find_derived_classes;
486 $find_derived_classes = sub {
487 my ($outer_class) = @_;
489 my $symbol_table_hashref = do { no strict 'refs'; \%{"${outer_class}::"} };
492 for my $symbol ( keys %$symbol_table_hashref ) {
493 next SYMBOL if $symbol !~ /\A (\w+):: \z/x;
494 my $inner_class = $1;
496 next SYMBOL if $inner_class eq 'SUPER'; # skip '*::SUPER'
500 ? "${outer_class}::$inner_class"
503 if ( $class->isa($super_class) and $class ne $super_class ) {
504 push @derived_classes, $class;
507 next SYMBOL if $class eq 'main'; # skip 'main::*'
509 $find_derived_classes->($class);
513 my $root_class = q{};
514 $find_derived_classes->($root_class);
516 undef $find_derived_classes;
518 @derived_classes = sort { $a->isa($b) ? 1 : $b->isa($a) ? -1 : 0 } @derived_classes;
520 return @derived_classes;
526 return @{ mro::get_linear_isa( (shift)->name ) };
529 sub class_precedence_list {
531 my $name = $self->name;
533 unless (Class::MOP::IS_RUNNING_ON_5_10()) {
535 # We need to check for circular inheritance here
536 # if we are are not on 5.10, cause 5.8 detects it
537 # late. This will do nothing if all is well, and
538 # blow up otherwise. Yes, it's an ugly hack, better
539 # suggestions are welcome.
541 ($name || return)->isa('This is a test for circular inheritance')
544 # if our mro is c3, we can
545 # just grab the linear_isa
546 if (mro::get_mro($name) eq 'c3') {
547 return @{ mro::get_linear_isa($name) }
551 # we can't grab the linear_isa for dfs
552 # since it has all the duplicates
557 $self->initialize($_)->class_precedence_list()
558 } $self->superclasses()
565 sub wrap_method_body {
566 my ( $self, %args ) = @_;
568 ('CODE' eq ref $args{body})
569 || confess "Your code block must be a CODE reference";
571 $self->method_metaclass->wrap(
572 package_name => $self->name,
578 my ($self, $method_name, $method) = @_;
579 (defined $method_name && $method_name)
580 || confess "You must define a method name";
583 if (blessed($method)) {
584 $body = $method->body;
585 if ($method->package_name ne $self->name) {
586 $method = $method->clone(
587 package_name => $self->name,
589 ) if $method->can('clone');
594 $method = $self->wrap_method_body( body => $body, name => $method_name );
597 $method->attach_to_class($self);
599 # This used to call get_method_map, which meant we would build all
600 # the method objects for the class just because we added one
601 # method. This is hackier, but quicker too.
602 $self->{methods}{$method_name} = $method;
604 my $full_method_name = ($self->name . '::' . $method_name);
605 $self->add_package_symbol(
606 { sigil => '&', type => 'CODE', name => $method_name },
607 Class::MOP::subname($full_method_name => $body)
612 my $fetch_and_prepare_method = sub {
613 my ($self, $method_name) = @_;
614 my $wrapped_metaclass = $self->wrapped_method_metaclass;
616 my $method = $self->get_method($method_name);
617 # if we dont have local ...
619 # try to find the next method
620 $method = $self->find_next_method_by_name($method_name);
621 # die if it does not exist
623 || confess "The method '$method_name' was not found in the inheritance hierarchy for " . $self->name;
624 # and now make sure to wrap it
625 # even if it is already wrapped
626 # because we need a new sub ref
627 $method = $wrapped_metaclass->wrap($method);
630 # now make sure we wrap it properly
631 $method = $wrapped_metaclass->wrap($method)
632 unless $method->isa($wrapped_metaclass);
634 $self->add_method($method_name => $method);
638 sub add_before_method_modifier {
639 my ($self, $method_name, $method_modifier) = @_;
640 (defined $method_name && $method_name)
641 || confess "You must pass in a method name";
642 my $method = $fetch_and_prepare_method->($self, $method_name);
643 $method->add_before_modifier(
644 Class::MOP::subname(':before' => $method_modifier)
648 sub add_after_method_modifier {
649 my ($self, $method_name, $method_modifier) = @_;
650 (defined $method_name && $method_name)
651 || confess "You must pass in a method name";
652 my $method = $fetch_and_prepare_method->($self, $method_name);
653 $method->add_after_modifier(
654 Class::MOP::subname(':after' => $method_modifier)
658 sub add_around_method_modifier {
659 my ($self, $method_name, $method_modifier) = @_;
660 (defined $method_name && $method_name)
661 || confess "You must pass in a method name";
662 my $method = $fetch_and_prepare_method->($self, $method_name);
663 $method->add_around_modifier(
664 Class::MOP::subname(':around' => $method_modifier)
669 # the methods above used to be named like this:
670 # ${pkg}::${method}:(before|after|around)
671 # but this proved problematic when using one modifier
672 # to wrap multiple methods (something which is likely
673 # to happen pretty regularly IMO). So instead of naming
674 # it like this, I have chosen to just name them purely
675 # with their modifier names, like so:
676 # :(before|after|around)
677 # The fact is that in a stack trace, it will be fairly
678 # evident from the context what method they are attached
679 # to, and so don't need the fully qualified name.
685 $self->add_method(@_);
689 my ($self, $method_name) = @_;
690 (defined $method_name && $method_name)
691 || confess "You must define a method name";
693 exists $self->{methods}{$method_name} || exists $self->get_method_map->{$method_name};
697 my ($self, $method_name) = @_;
698 (defined $method_name && $method_name)
699 || confess "You must define a method name";
701 return $self->{methods}{$method_name} || $self->get_method_map->{$method_name};
705 my ($self, $method_name) = @_;
706 (defined $method_name && $method_name)
707 || confess "You must define a method name";
709 my $removed_method = delete $self->get_method_map->{$method_name};
711 $self->remove_package_symbol(
712 { sigil => '&', type => 'CODE', name => $method_name }
715 $removed_method->detach_from_class if $removed_method;
717 $self->update_package_cache_flag; # still valid, since we just removed the method from the map
719 return $removed_method;
722 sub get_method_list {
724 keys %{$self->get_method_map};
727 sub find_method_by_name {
728 my ($self, $method_name) = @_;
729 (defined $method_name && $method_name)
730 || confess "You must define a method name to find";
731 foreach my $class ($self->linearized_isa) {
732 # fetch the meta-class ...
733 my $meta = $self->initialize($class);
734 return $meta->get_method($method_name)
735 if $meta->has_method($method_name);
740 sub get_all_methods {
742 my %methods = map { %{ $self->initialize($_)->get_method_map } } reverse $self->linearized_isa;
743 return values %methods;
747 sub compute_all_applicable_methods {
751 class => $_->package_name,
752 code => $_, # sigh, overloading
754 } shift->get_all_methods(@_);
757 sub get_all_method_names {
760 grep { $uniq{$_}++ == 0 } map { $_->name } $self->get_all_methods;
763 sub find_all_methods_by_name {
764 my ($self, $method_name) = @_;
765 (defined $method_name && $method_name)
766 || confess "You must define a method name to find";
768 foreach my $class ($self->linearized_isa) {
769 # fetch the meta-class ...
770 my $meta = $self->initialize($class);
772 name => $method_name,
774 code => $meta->get_method($method_name)
775 } if $meta->has_method($method_name);
780 sub find_next_method_by_name {
781 my ($self, $method_name) = @_;
782 (defined $method_name && $method_name)
783 || confess "You must define a method name to find";
784 my @cpl = $self->linearized_isa;
785 shift @cpl; # discard ourselves
786 foreach my $class (@cpl) {
787 # fetch the meta-class ...
788 my $meta = $self->initialize($class);
789 return $meta->get_method($method_name)
790 if $meta->has_method($method_name);
799 # either we have an attribute object already
800 # or we need to create one from the args provided
801 my $attribute = blessed($_[0]) ? $_[0] : $self->attribute_metaclass->new(@_);
802 # make sure it is derived from the correct type though
803 ($attribute->isa('Class::MOP::Attribute'))
804 || confess "Your attribute must be an instance of Class::MOP::Attribute (or a subclass)";
806 # first we attach our new attribute
807 # because it might need certain information
808 # about the class which it is attached to
809 $attribute->attach_to_class($self);
811 # then we remove attributes of a conflicting
812 # name here so that we can properly detach
813 # the old attr object, and remove any
814 # accessors it would have generated
815 if ( $self->has_attribute($attribute->name) ) {
816 $self->remove_attribute($attribute->name);
818 $self->invalidate_meta_instances();
821 # then onto installing the new accessors
822 $self->get_attribute_map->{$attribute->name} = $attribute;
824 # invalidate package flag here
825 my $e = do { local $@; eval { $attribute->install_accessors() }; $@ };
827 $self->remove_attribute($attribute->name);
834 sub update_meta_instance_dependencies {
837 if ( $self->{meta_instance_dependencies} ) {
838 return $self->add_meta_instance_dependencies;
842 sub add_meta_instance_dependencies {
845 $self->remove_meta_instance_dependencies;
847 my @attrs = $self->compute_all_applicable_attributes();
850 my @classes = grep { not $seen{$_->name}++ } map { $_->associated_class } @attrs;
852 foreach my $class ( @classes ) {
853 $class->add_dependent_meta_instance($self);
856 $self->{meta_instance_dependencies} = \@classes;
859 sub remove_meta_instance_dependencies {
862 if ( my $classes = delete $self->{meta_instance_dependencies} ) {
863 foreach my $class ( @$classes ) {
864 $class->remove_dependent_meta_instance($self);
874 sub add_dependent_meta_instance {
875 my ( $self, $metaclass ) = @_;
876 push @{ $self->{dependent_meta_instances} }, $metaclass;
879 sub remove_dependent_meta_instance {
880 my ( $self, $metaclass ) = @_;
881 my $name = $metaclass->name;
882 @$_ = grep { $_->name ne $name } @$_ for $self->{dependent_meta_instances};
885 sub invalidate_meta_instances {
887 $_->invalidate_meta_instance() for $self, @{ $self->{dependent_meta_instances} };
890 sub invalidate_meta_instance {
892 undef $self->{_meta_instance};
896 my ($self, $attribute_name) = @_;
897 (defined $attribute_name && $attribute_name)
898 || confess "You must define an attribute name";
899 exists $self->get_attribute_map->{$attribute_name};
903 my ($self, $attribute_name) = @_;
904 (defined $attribute_name && $attribute_name)
905 || confess "You must define an attribute name";
906 return $self->get_attribute_map->{$attribute_name}
908 # this will return undef anyway, so no need ...
909 # if $self->has_attribute($attribute_name);
913 sub remove_attribute {
914 my ($self, $attribute_name) = @_;
915 (defined $attribute_name && $attribute_name)
916 || confess "You must define an attribute name";
917 my $removed_attribute = $self->get_attribute_map->{$attribute_name};
918 return unless defined $removed_attribute;
919 delete $self->get_attribute_map->{$attribute_name};
920 $self->invalidate_meta_instances();
921 $removed_attribute->remove_accessors();
922 $removed_attribute->detach_from_class();
923 return $removed_attribute;
926 sub get_attribute_list {
928 keys %{$self->get_attribute_map};
931 sub get_all_attributes {
932 shift->compute_all_applicable_attributes(@_);
935 sub compute_all_applicable_attributes {
937 my %attrs = map { %{ $self->initialize($_)->get_attribute_map } } reverse $self->linearized_isa;
938 return values %attrs;
941 sub find_attribute_by_name {
942 my ($self, $attr_name) = @_;
943 foreach my $class ($self->linearized_isa) {
944 # fetch the meta-class ...
945 my $meta = $self->initialize($class);
946 return $meta->get_attribute($attr_name)
947 if $meta->has_attribute($attr_name);
952 # check if we can reinitialize
956 # if any local attr is defined
957 return if $self->get_attribute_list;
959 # or any non-declared methods
960 if ( my @methods = values %{ $self->get_method_map } ) {
961 my $metaclass = $self->method_metaclass;
962 foreach my $method ( @methods ) {
963 return if $method->isa("Class::MOP::Method::Generated");
964 # FIXME do we need to enforce this too? return unless $method->isa($metaclass);
974 sub is_immutable { 0 }
977 # Why I changed this (groditi)
978 # - One Metaclass may have many Classes through many Metaclass instances
979 # - One Metaclass should only have one Immutable Transformer instance
980 # - Each Class may have different Immutabilizing options
981 # - Therefore each Metaclass instance may have different Immutabilizing options
982 # - We need to store one Immutable Transformer instance per Metaclass
983 # - We need to store one set of Immutable Transformer options per Class
984 # - Upon make_mutable we may delete the Immutabilizing options
985 # - We could clean the immutable Transformer instance when there is no more
986 # immutable Classes of that type, but we can also keep it in case
987 # another class with this same Metaclass becomes immutable. It is a case
988 # of trading of storing an instance to avoid unnecessary instantiations of
989 # Immutable Transformers. You may view this as a memory leak, however
990 # Because we have few Metaclasses, in practice it seems acceptable
991 # - To allow Immutable Transformers instances to be cleaned up we could weaken
992 # the reference stored in $IMMUTABLE_TRANSFORMERS{$class} and ||= should DWIM
996 my %IMMUTABLE_TRANSFORMERS;
997 my %IMMUTABLE_OPTIONS;
999 sub get_immutable_options {
1001 return if $self->is_mutable;
1002 confess "unable to find immutabilizing options"
1003 unless exists $IMMUTABLE_OPTIONS{$self->name};
1004 my %options = %{$IMMUTABLE_OPTIONS{$self->name}};
1005 delete $options{IMMUTABLE_TRANSFORMER};
1009 sub get_immutable_transformer {
1011 if( $self->is_mutable ){
1012 return $IMMUTABLE_TRANSFORMERS{$self->name} ||= $self->create_immutable_transformer;
1014 confess "unable to find transformer for immutable class"
1015 unless exists $IMMUTABLE_OPTIONS{$self->name};
1016 return $IMMUTABLE_OPTIONS{$self->name}->{IMMUTABLE_TRANSFORMER};
1019 sub make_immutable {
1023 my $transformer = $self->get_immutable_transformer;
1024 $transformer->make_metaclass_immutable($self, \%options);
1025 $IMMUTABLE_OPTIONS{$self->name} =
1026 { %options, IMMUTABLE_TRANSFORMER => $transformer };
1028 if( exists $options{debug} && $options{debug} ){
1029 print STDERR "# of Metaclass options: ", keys %IMMUTABLE_OPTIONS;
1030 print STDERR "# of Immutable transformers: ", keys %IMMUTABLE_TRANSFORMERS;
1038 return if $self->is_mutable;
1039 my $options = delete $IMMUTABLE_OPTIONS{$self->name};
1040 confess "unable to find immutabilizing options" unless ref $options;
1041 my $transformer = delete $options->{IMMUTABLE_TRANSFORMER};
1042 $transformer->make_metaclass_mutable($self, $options);
1047 sub create_immutable_transformer {
1049 my $class = Class::MOP::Immutable->new($self, {
1050 read_only => [qw/superclasses/],
1057 remove_package_symbol
1060 class_precedence_list => 'ARRAY',
1061 linearized_isa => 'ARRAY', # FIXME perl 5.10 memoizes this on its own, no need?
1062 get_all_methods => 'ARRAY',
1063 get_all_method_names => 'ARRAY',
1064 #get_all_attributes => 'ARRAY', # it's an alias, no need, but maybe in the future
1065 compute_all_applicable_attributes => 'ARRAY',
1066 get_meta_instance => 'SCALAR',
1067 get_method_map => 'SCALAR',
1070 # this is ugly, but so are typeglobs,
1071 # so whattayahgonnadoboutit
1074 add_package_symbol => sub {
1075 my $original = shift;
1076 confess "Cannot add package symbols to an immutable metaclass"
1077 unless (caller(2))[3] eq 'Class::MOP::Package::get_package_symbol';
1079 # This is a workaround for a bug in 5.8.1 which thinks that
1080 # goto $original->body
1081 # is trying to go to a label
1082 my $body = $original->body;
1098 Class::MOP::Class - Class Meta Object
1102 # assuming that class Foo
1103 # has been defined, you can
1105 # use this for introspection ...
1107 # add a method to Foo ...
1108 Foo->meta->add_method( 'bar' => sub {...} )
1110 # get a list of all the classes searched
1111 # the method dispatcher in the correct order
1112 Foo->meta->class_precedence_list()
1114 # remove a method from Foo
1115 Foo->meta->remove_method('bar');
1117 # or use this to actually create classes ...
1119 Class::MOP::Class->create(
1122 superclasses => ['Foo'],
1124 Class::MOP:: : Attribute->new('$bar'),
1125 Class::MOP:: : Attribute->new('$baz'),
1128 calculate_bar => sub {...},
1129 construct_baz => sub {...}
1136 This is the largest and most complex part of the Class::MOP
1137 meta-object protocol. It controls the introspection and manipulation
1138 of Perl 5 classes, and it can create them as wlel. The best way to
1139 understand what this module can do, is to read the documentation for
1140 each of its methods.
1144 C<Class::MOP::Class> is a subclass of L<Class::MOP::Module>.
1148 =head2 Class construction
1150 These methods all create new C<Class::MOP::Class> objects. These
1151 objects can represent existing classes, or they can be used to create
1152 new classes from scratch.
1154 The metaclass object for a given class is a singleton. If you attempt
1155 to create a metaclass for the same class twice, you will just get the
1160 =item B<< Class::MOP::Class->create($package_name, %options) >>
1162 This method creates a new C<Class::MOP::Class> object with the given
1163 package name. It accepts a number of options.
1169 An optional version number for the newly created package.
1173 An optional authority for the newly created package.
1175 =item * superclasses
1177 An optional array reference of superclass names.
1181 An optional hash reference of methods for the class. The keys of the
1182 hash reference are method names, and values are subroutine references.
1186 An optional array reference of attributes.
1188 An attribute can be passed as an existing L<Class::MOP::Attribute>
1189 object, I<or> or as a hash reference of options which will be passed
1190 to the attribute metaclass's constructor.
1194 =item B<< Class::MOP::Class->create_anon_class(%options) >>
1196 This method works just like C<< Class::MOP::Class->create >> but it
1197 creates an "anonymous" class. In fact, the class does have a name, but
1198 that name is a unique name generated internally by this module.
1200 It accepts the same C<superclasses>, C<methods>, and C<attributes>
1201 parameters that C<create> accepts.
1203 Anonymous classes are destroyed once the metaclass they are attached
1204 to goes out of scope, and will be removed from Perl's internal symbol
1207 All instances of an anonymous class keep a special reference to the
1208 metaclass object, which prevents the metaclass from going out of scope
1209 while any instances exist.
1211 This only works if the instance if based on a hash reference, however.
1213 =item B<< Class::MOP::Class->initialize($package_name, %options) >>
1215 This method will initialize a C<Class::MOP::Class> object for the
1216 named package. Unlike C<create>, this method I<will not> create a new
1219 The purpose of this method is to retrieve a C<Class::MOP::Class>
1220 object for introspecting an existing class.
1222 If an existing C<Class::MOP::Class> object exists for the named
1223 package, it will be returned, and any options provided will be
1226 If the object does not yet exist, it will be created.
1228 The valid options that can be passed to this method are
1229 C<attribute_metaclass>, C<method_metaclass>,
1230 C<wrapped_method_metaclass>, and C<instance_metaclass>. These are all
1231 optional, and default to the appropriate class in the C<Class::MOP>
1236 =head2 Object instance construction and cloning
1238 These methods are all related to creating and/or cloning object
1243 =item B<< $metaclass->clone_object($instance, %params) >>
1245 This method clones an existing object instance. Any parameters you
1246 provide are will override existing attribute values in the object.
1248 This is a convience method for cloning an object instance, then
1249 blessing it into the appropriate package.
1251 You could implement a clone method in your class, using this method:
1254 my ($self, %params) = @_;
1255 $self->meta->clone_object($self, %params);
1258 =item B<< $metaclass->rebless_instance($instance, %params) >>
1260 This method changes the class of C<$instance> to the metaclass's class.
1262 You can only rebless an instance into a subclass of its current
1263 class. If you pass any additional parameters, these will be treated
1264 like constructor parameters and used to initialize the object's
1265 attributes. Any existing attributes that are already set will be
1268 =item B<< $metaclass->new_object(%params) >
1270 This method is used to create a new object of the metaclass's
1271 class. Any parameters you provide are used to initialize the
1272 instance's attributes.
1274 =item B<< $metaclass->instance_metaclass >>
1276 Returns the class name of the instance metaclass, see
1277 L<Class::MOP::Instance> for more information on the instance
1280 =item B<< $metaclass->get_meta_instance >>
1282 Returns an instance of the C<instance_metaclass> to be used in the
1283 construction of a new instance of the class.
1287 =head2 Informational predicates
1289 These are a few predicate methods for asking information about the
1294 =item B<< $metaclass->is_anon_class >>
1296 This returns true if the class was created by calling C<<
1297 Class::MOP::Class->create_anon_class >>.
1299 =item B<< $metaclass->is_mutable >>
1301 This returns true if the class is still mutable.
1303 =item B<< $metaclass->is_immutable >>
1305 This returns true if the class has been made immutable.
1307 =item B<< $metaclass->is_pristine >>
1309 A class is I<not> pristine if it has non-inherited attributes or if it
1310 has any generated methods.
1314 =head2 Inheritance Relationships
1318 =item B<< $metaclass->superclasses(@superclasses) >>
1320 This is a read-write accessor which represents the superclass
1321 relationships of the metaclass's class.
1323 This is basically sugar around getting and setting C<@ISA>.
1325 =item B<< $metaclass->class_precedence_list >>
1327 This returns a list of all of the class's ancestor classes. The
1328 classes are returned in method dispatch order.
1330 =item B<< $metaclass->linearized_isa >>
1332 This returns a list based on C<class_precedence_list> but with all
1335 =item B<< $metaclass->subclasses >>
1337 This returns a list of subclasses for this class.
1341 =head2 Method introspection and creation
1343 These methods allow you to introspect a class's methods, as well as
1344 add, remove, or change methods.
1346 Determining what is truly a method in a Perl 5 class requires some
1347 heuristics (aka guessing).
1349 Methods defined outside the package with a fully qualified name (C<sub
1350 Package::name { ... }>) will be included. Similarly, methods named
1351 with a fully qualified name using L<Sub::Name> are also included.
1353 However, we attempt to ignore imported functions.
1355 Ultimately, we are using heuristics to determine what truly is a
1356 method in a class, and these heuristics may get the wrong answer in
1357 some edge cases. However, for most "normal" cases the heuristics work
1362 =item B<< $metaclass->get_method($method_name) >>
1364 This will return a L<Class::MOP::Method> for the specified
1365 C<$method_name>. If the class does not have the specified method, it
1368 =item B<< $metaclass->has_method($method_name) >>
1370 Returns a boolean indicating whether or not the class defines the
1371 named method. It does not include methods inherited from parent
1374 =item B<< $metaclass->get_method_map >>
1376 Returns a hash reference representing the methods defined in this
1377 class. The keys are method names and the values are
1378 L<Class::MOP::Method> objects.
1380 =item B<< $metaclass->get_method_list >>
1382 This will return a list of method I<names> for all methods defined in
1385 =item B<< $metaclass->get_all_methods >>
1387 This will traverse the inheritance hierarchy and return a list of all
1388 the L<Class::MOP::Method> objects for this class and its parents.
1390 =item B<< $metaclass->find_method_by_name($method_name) >>
1392 This will return a L<Class::MOP::Method> for the specified
1393 C<$method_name>. If the class does not have the specified method, it
1396 Unlike C<get_method>, this method I<will> look for the named method in
1399 =item B<< $metaclass->get_all_method_names >>
1401 This will return a list of method I<names> for all of this class's
1402 methods, including inherited methods.
1404 =item B<< $metaclass->find_all_methods_by_name($method_name) >>
1406 This method looks for the named method in the class and all of its
1407 parents. It returns every matching method it finds in the inheritance
1408 tree, so it returns a list of methods.
1410 Each method is returned as a hash reference with three keys. The keys
1411 are C<name>, C<class>, and C<code>. The C<code> key has a
1412 L<Class::MOP::Method> object as its value.
1414 The list of methods is distinct.
1416 =item B<< $metaclass->find_next_method_by_name($method_name) >>
1418 This method returns the first method in any superclass matching the
1419 given name. It is effectively the method that C<SUPER::$method_name>
1424 =head2 Attribute introspection and creation
1426 Because Perl 5 does not have a core concept of attributes in classes,
1427 we can only return information about attributes which have been added
1428 via this class's methods. We cannot discover information about
1429 attributes which are defined in terms of "regular" Perl 5 methods.
1433 =item B<< $metaclass->get_attribute($attribute_name) >>
1435 This will return a L<Class::MOP::Attribute> for the specified
1436 C<$attribute_name>. If the class does not have the specified
1437 attribute, it returns C<undef>
1439 =item B<< $metaclass->has_attribute($attribute_name) >>
1441 Returns a boolean indicating whether or not the class defines the
1442 named attribute. It does not include attributes inherited from parent
1445 =item B<< $metaclass->get_attribute_map >>
1447 Returns a hash reference representing the attributes defined in this
1448 class. The keys are attribute names and the values are
1449 L<Class::MOP::Attribute> objects.
1451 =item B<< $metaclass->get_attribute_list >>
1453 This will return a list of attributes I<names> for all attributes
1454 defined in this class.
1456 =item B<< $metaclass->get_all_attributes >>
1458 This will traverse the inheritance hierarchy and return a list of all
1459 the L<Class::MOP::Attribute> objects for this class and its parents.
1461 This method can also be called as C<compute_all_applicable_attributes>.
1463 =item B<< $metaclass->find_attribute_by_name($attribute_name) >>
1465 This will return a L<Class::MOP::Attribute> for the specified
1466 C<$attribute_name>. If the class does not have the specified
1467 attribute, it returns C<undef>
1469 Unlike C<get_attribute>, this attribute I<will> look for the named
1470 attribute in superclasses.
1472 =item B<< $metaclass->add_attribute(...) >>
1474 This method accepts either an existing L<Class::MOP::Attribute>
1475 object, or parameters suitable for passing to that class's C<new>
1478 The attribute provided will be added to the class.
1480 Any accessor methods defined by the attribute will be added to the
1481 class when the attribute is added.
1483 If an attribute of the same name already exists, the old attribute
1484 will be removed first.
1486 =item B<< $metaclass->remove_attribute($attribute_name) >>
1488 This will remove the named attribute from the class, and
1489 L<Class::MOP::Attribute> object.
1491 Removing an attribute also removes any accessor methods defined by the
1494 However, note that removing an attribute will only affect I<future>
1495 object instances created for this class, not existing instances.
1497 =item B<< $metaclass->attribute_metaclass >>
1499 Returns the class name of the attribute metaclass for this class. By
1500 default, this is L<Class::MOP::Attribute>. for more information on
1504 =head2 Class Immutability
1506 Making a class immutable "freezes" the class definition. You can no
1507 longer call methods which alter the class, such as adding or removing
1508 methods or attributes.
1510 Making a class immutable lets us optimize the class by inlning some
1511 methods, and also allows us to optimize some methods on the metaclass
1514 The immutabilization system in L<Moose> takes much greater advantage
1515 of the inlining features than Class::MOP itself does.
1519 =item B<< $metaclass->make_immutable(%options) >>
1521 This method will create an immutable transformer and uses it to make
1522 the class and its metaclass object immutable.
1524 Details of how immutabilization works are in L<Class::MOP::Immutable>
1527 =item B<< $metaclass->make_mutable >>
1529 Calling this method reverse the immutabilization transformation.
1531 =item B<< $metaclass->get_immutable_transformer >>
1533 If the class has been made immutable previously, this returns the
1534 L<Class::MOP::Immutable> object that was created to do the
1537 If the class was never made immutable, this method will die.
1541 =head2 Method Modifiers
1543 Method modifiers are hooks which allow a method to be wrapped with
1544 I<before>, I<after> and I<around> method modifiers. Every time a
1545 method is called, it's modifiers are also called.
1547 A class can modify its own methods, as well as methods defined in
1550 =head3 How method modifiers work?
1552 Method modifiers work by wrapping the original method and then
1553 replacing it in the class's symbol table. The wrappers will handle
1554 calling all the modifiers in the appropariate orders and preserving
1555 the calling context for the original method.
1557 The return values of C<before> and C<after> modifiers are
1558 ignored. This is because their purpose is B<not> to filter the input
1559 and output of the primary method (this is done with an I<around>
1562 This may seem like an odd restriction to some, but doing this allows
1563 for simple code to be added at the beginning or end of a method call
1564 without altering the function of the wrapped method or placing any
1565 extra responsibility on the code of the modifier.
1567 Of course if you have more complex needs, you can use the C<around>
1568 modifier which allows you to change both the parameters passed to the
1569 wrapped method, as well as its return value.
1571 Before and around modifiers are called in last-defined-first-called
1572 order, while after modifiers are called in first-defined-first-called
1573 order. So the call tree might looks something like this:
1585 =head3 What is the performance impact?
1587 Of course there is a performance cost associated with method
1588 modifiers, but we have made every effort to make that cost directly
1589 proportional to the number of modifier features you utilize.
1591 The wrapping method does it's best to B<only> do as much work as it
1592 absolutely needs to. In order to do this we have moved some of the
1593 performance costs to set-up time, where they are easier to amortize.
1595 All this said, our benchmarks have indicated the following:
1597 simple wrapper with no modifiers 100% slower
1598 simple wrapper with simple before modifier 400% slower
1599 simple wrapper with simple after modifier 450% slower
1600 simple wrapper with simple around modifier 500-550% slower
1601 simple wrapper with all 3 modifiers 1100% slower
1603 These numbers may seem daunting, but you must remember, every feature
1604 comes with some cost. To put things in perspective, just doing a
1605 simple C<AUTOLOAD> which does nothing but extract the name of the
1606 method called and return it costs about 400% over a normal method
1611 =item B<< $metaclass->add_before_method_modifier($method_name, $code) >>
1613 This wraps the specified method with the supplied subroutine
1614 reference. The modifier will be called as a method itself, and will
1615 receive the same arguments as are passed to the method.
1617 When the modifier exits, the wrapped method will be called.
1619 The return value of the modifier will be ignored.
1621 =item B<< $metaclass->add_after_method_modifier($method_name, $code) >>
1623 This wraps the specified method with the supplied subroutine
1624 reference. The modifier will be called as a method itself, and will
1625 receive the same arguments as are passed to the method.
1627 When the wrapped methods exits, the modifier will be called.
1629 The return value of the modifier will be ignored.
1631 =item B<< $metaclass->add_around_method_modifier($method_name, $code) >>
1633 This wraps the specified method with the supplied subroutine
1636 The first argument passed to the modifier will be a subroutine
1637 reference to the wrapped method. The second argument is the object,
1638 and after that come any arguments passed when the method is called.
1640 The around modifier can choose to call the original method, as well as
1641 what arguments to pass if it does so.
1643 The return value of the modifier is what will be seen by the caller.
1649 Stevan Little E<lt>stevan@iinteractive.comE<gt>
1651 =head1 COPYRIGHT AND LICENSE
1653 Copyright 2006-2009 by Infinity Interactive, Inc.
1655 L<http://www.iinteractive.com>
1657 This library is free software; you can redistribute it and/or modify
1658 it under the same terms as Perl itself.