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') {
76 $meta = $class->_new($options);
80 # it is safe to use meta here because
81 # class will always be a subclass of
82 # Class::MOP::Class, which defines meta
83 $meta = $class->meta->construct_instance($options)
86 # and check the metaclass compatibility
87 $meta->check_metaclass_compatibility();
89 Class::MOP::store_metaclass_by_name($package_name, $meta);
92 # we need to weaken any anon classes
93 # so that they can call DESTROY properly
94 Class::MOP::weaken_metaclass($package_name) if $meta->is_anon_class;
101 my $options = @_ == 1 ? $_[0] : {@_};
104 # inherited from Class::MOP::Package
105 'package' => $options->{package},
108 # since the following attributes will
109 # actually be loaded from the symbol
110 # table, and actually bypass the instance
111 # entirely, we can just leave these things
112 # listed here for reference, because they
113 # should not actually have a value associated
115 'namespace' => \undef,
117 # inherited from Class::MOP::Module
119 'authority' => \undef,
121 # defined in Class::MOP::Class
122 'superclasses' => \undef,
126 'attribute_metaclass' => $options->{'attribute_metaclass'}
127 || 'Class::MOP::Attribute',
128 'method_metaclass' => $options->{'method_metaclass'}
129 || 'Class::MOP::Method',
130 'wrapped_method_metaclass' => $options->{'wrapped_method_metaclass'}
131 || 'Class::MOP::Method::Wrapped',
132 'instance_metaclass' => $options->{'instance_metaclass'}
133 || 'Class::MOP::Instance',
137 sub reset_package_cache_flag { (shift)->{'_package_cache_flag'} = undef }
138 sub update_package_cache_flag {
141 # we can manually update the cache number
142 # since we are actually adding the method
143 # to our cache as well. This avoids us
144 # having to regenerate the method_map.
146 $self->{'_package_cache_flag'} = Class::MOP::check_package_cache_flag($self->name);
149 sub check_metaclass_compatibility {
152 # this is always okay ...
153 return if ref($self) eq 'Class::MOP::Class' &&
154 $self->instance_metaclass eq 'Class::MOP::Instance';
156 my @class_list = $self->linearized_isa;
157 shift @class_list; # shift off $self->name
159 foreach my $superclass_name (@class_list) {
160 my $super_meta = Class::MOP::get_metaclass_by_name($superclass_name) || next;
163 # we need to deal with the possibility
164 # of class immutability here, and then
165 # get the name of the class appropriately
167 = $super_meta->is_immutable
168 ? $super_meta->get_mutable_metaclass_name()
171 ($self->isa($super_meta_type))
172 || confess $self->name . "->meta => (" . (ref($self)) . ")" .
173 " is not compatible with the " .
174 $superclass_name . "->meta => (" . ($super_meta_type) . ")";
176 # we also need to check that instance metaclasses
177 # are compatibile in the same the class.
178 ($self->instance_metaclass->isa($super_meta->instance_metaclass))
179 || confess $self->name . "->meta->instance_metaclass => (" . ($self->instance_metaclass) . ")" .
180 " is not compatible with the " .
181 $superclass_name . "->meta->instance_metaclass => (" . ($super_meta->instance_metaclass) . ")";
189 # this should be sufficient, if you have a
190 # use case where it is not, write a test and
192 my $ANON_CLASS_SERIAL = 0;
195 # we need a sufficiently annoying prefix
196 # this should suffice for now, this is
197 # used in a couple of places below, so
198 # need to put it up here for now.
199 my $ANON_CLASS_PREFIX = 'Class::MOP::Class::__ANON__::SERIAL::';
203 no warnings 'uninitialized';
204 $self->name =~ /^$ANON_CLASS_PREFIX/;
207 sub create_anon_class {
208 my ($class, %options) = @_;
209 my $package_name = $ANON_CLASS_PREFIX . ++$ANON_CLASS_SERIAL;
210 return $class->create($package_name, %options);
214 # this will only get called for
215 # anon-classes, all other calls
216 # are assumed to occur during
217 # global destruction and so don't
218 # really need to be handled explicitly
222 return if Class::MOP::in_global_destruction(); # it'll happen soon anyway and this just makes things more complicated
224 no warnings 'uninitialized';
225 return unless $self->name =~ /^$ANON_CLASS_PREFIX/;
226 # Moose does a weird thing where it replaces the metaclass for
227 # class when fixing metaclass incompatibility. In that case,
228 # we don't want to clean out the namespace now. We can detect
229 # that because Moose will explicitly update the singleton
230 # cache in Class::MOP.
231 my $current_meta = Class::MOP::get_metaclass_by_name($self->name);
232 return if $current_meta ne $self;
234 my ($serial_id) = ($self->name =~ /^$ANON_CLASS_PREFIX(\d+)/);
236 foreach my $key (keys %{$ANON_CLASS_PREFIX . $serial_id}) {
237 delete ${$ANON_CLASS_PREFIX . $serial_id}{$key};
239 delete ${'main::' . $ANON_CLASS_PREFIX}{$serial_id . '::'};
244 # creating classes with MOP ...
247 my ( $class, @args ) = @_;
249 unshift @args, 'package' if @args % 2 == 1;
251 my (%options) = @args;
252 my $package_name = $options{package};
254 (ref $options{superclasses} eq 'ARRAY')
255 || confess "You must pass an ARRAY ref of superclasses"
256 if exists $options{superclasses};
258 (ref $options{attributes} eq 'ARRAY')
259 || confess "You must pass an ARRAY ref of attributes"
260 if exists $options{attributes};
262 (ref $options{methods} eq 'HASH')
263 || confess "You must pass a HASH ref of methods"
264 if exists $options{methods};
266 $class->SUPER::create(%options);
268 my (%initialize_options) = @args;
269 delete @initialize_options{qw(
277 my $meta = $class->initialize( $package_name => %initialize_options );
280 $meta->add_method('meta' => sub {
281 $class->initialize(ref($_[0]) || $_[0]);
284 $meta->superclasses(@{$options{superclasses}})
285 if exists $options{superclasses};
287 # process attributes first, so that they can
288 # install accessors, but locally defined methods
289 # can then overwrite them. It is maybe a little odd, but
290 # I think this should be the order of things.
291 if (exists $options{attributes}) {
292 foreach my $attr (@{$options{attributes}}) {
293 $meta->add_attribute($attr);
296 if (exists $options{methods}) {
297 foreach my $method_name (keys %{$options{methods}}) {
298 $meta->add_method($method_name, $options{methods}->{$method_name});
307 # all these attribute readers will be bootstrapped
308 # away in the Class::MOP bootstrap section
310 sub get_attribute_map { $_[0]->{'attributes'} }
311 sub attribute_metaclass { $_[0]->{'attribute_metaclass'} }
312 sub method_metaclass { $_[0]->{'method_metaclass'} }
313 sub wrapped_method_metaclass { $_[0]->{'wrapped_method_metaclass'} }
314 sub instance_metaclass { $_[0]->{'instance_metaclass'} }
316 # Instance Construction & Cloning
322 # we need to protect the integrity of the
323 # Class::MOP::Class singletons here, so we
324 # delegate this to &construct_class_instance
325 # which will deal with the singletons
326 return $class->construct_class_instance(@_)
327 if $class->name->isa('Class::MOP::Class');
328 return $class->construct_instance(@_);
331 sub construct_instance {
333 my $params = @_ == 1 ? $_[0] : {@_};
334 my $meta_instance = $class->get_meta_instance();
335 my $instance = $meta_instance->create_instance();
336 foreach my $attr ($class->compute_all_applicable_attributes()) {
337 $attr->initialize_instance_slot($meta_instance, $instance, $params);
340 # this will only work for a HASH instance type
341 if ($class->is_anon_class) {
342 (Scalar::Util::reftype($instance) eq 'HASH')
343 || confess "Currently only HASH based instances are supported with instance of anon-classes";
345 # At some point we should make this official
346 # as a reserved slot name, but right now I am
347 # going to keep it here.
348 # my $RESERVED_MOP_SLOT = '__MOP__';
349 $instance->{'__MOP__'} = $class;
355 sub get_meta_instance {
357 $self->{'_meta_instance'} ||= $self->create_meta_instance();
360 sub create_meta_instance {
363 my $instance = $self->instance_metaclass->new(
364 associated_metaclass => $self,
365 attributes => [ $self->compute_all_applicable_attributes() ],
368 $self->add_meta_instance_dependencies()
369 if $instance->is_dependent_on_superclasses();
376 my $instance = shift;
377 (blessed($instance) && $instance->isa($class->name))
378 || confess "You must pass an instance of the metaclass (" . (ref $class ? $class->name : $class) . "), not ($instance)";
381 # we need to protect the integrity of the
382 # Class::MOP::Class singletons here, they
383 # should not be cloned.
384 return $instance if $instance->isa('Class::MOP::Class');
385 $class->clone_instance($instance, @_);
389 my ($class, $instance, %params) = @_;
391 || confess "You can only clone instances, ($instance) is not a blessed instance";
392 my $meta_instance = $class->get_meta_instance();
393 my $clone = $meta_instance->clone_instance($instance);
394 foreach my $attr ($class->compute_all_applicable_attributes()) {
395 if ( defined( my $init_arg = $attr->init_arg ) ) {
396 if (exists $params{$init_arg}) {
397 $attr->set_value($clone, $params{$init_arg});
404 sub rebless_instance {
405 my ($self, $instance, %params) = @_;
408 if ($instance->can('meta')) {
409 ($instance->meta->isa('Class::MOP::Class'))
410 || confess 'Cannot rebless instance if ->meta is not an instance of Class::MOP::Class';
411 $old_metaclass = $instance->meta;
414 $old_metaclass = $self->initialize(ref($instance));
417 my $meta_instance = $self->get_meta_instance();
419 $self->name->isa($old_metaclass->name)
420 || confess "You may rebless only into a subclass of (". $old_metaclass->name ."), of which (". $self->name .") isn't.";
423 # we use $_[1] here because of t/306_rebless_overload.t regressions on 5.8.8
424 $meta_instance->rebless_instance_structure($_[1], $self);
426 foreach my $attr ( $self->compute_all_applicable_attributes ) {
427 if ( $attr->has_value($instance) ) {
428 if ( defined( my $init_arg = $attr->init_arg ) ) {
429 $params{$init_arg} = $attr->get_value($instance)
430 unless exists $params{$init_arg};
433 $attr->set_value($instance, $attr->get_value($instance));
438 foreach my $attr ($self->compute_all_applicable_attributes) {
439 $attr->initialize_instance_slot($meta_instance, $instance, \%params);
449 my $var_spec = { sigil => '@', type => 'ARRAY', name => 'ISA' };
452 @{$self->get_package_symbol($var_spec)} = @supers;
455 # on 5.8 and below, we need to call
456 # a method to get Perl to detect
457 # a cycle in the class hierarchy
458 my $class = $self->name;
462 # we need to check the metaclass
463 # compatibility here so that we can
464 # be sure that the superclass is
465 # not potentially creating an issues
466 # we don't know about
468 $self->check_metaclass_compatibility();
469 $self->update_meta_instance_dependencies();
471 @{$self->get_package_symbol($var_spec)};
477 my $super_class = $self->name;
479 if ( Class::MOP::HAVE_ISAREV() ) {
480 return @{ $super_class->mro::get_isarev() };
484 my $find_derived_classes;
485 $find_derived_classes = sub {
486 my ($outer_class) = @_;
488 my $symbol_table_hashref = do { no strict 'refs'; \%{"${outer_class}::"} };
491 for my $symbol ( keys %$symbol_table_hashref ) {
492 next SYMBOL if $symbol !~ /\A (\w+):: \z/x;
493 my $inner_class = $1;
495 next SYMBOL if $inner_class eq 'SUPER'; # skip '*::SUPER'
499 ? "${outer_class}::$inner_class"
502 if ( $class->isa($super_class) and $class ne $super_class ) {
503 push @derived_classes, $class;
506 next SYMBOL if $class eq 'main'; # skip 'main::*'
508 $find_derived_classes->($class);
512 my $root_class = q{};
513 $find_derived_classes->($root_class);
515 undef $find_derived_classes;
517 @derived_classes = sort { $a->isa($b) ? 1 : $b->isa($a) ? -1 : 0 } @derived_classes;
519 return @derived_classes;
525 return @{ mro::get_linear_isa( (shift)->name ) };
528 sub class_precedence_list {
530 my $name = $self->name;
532 unless (Class::MOP::IS_RUNNING_ON_5_10()) {
534 # We need to check for circular inheritance here
535 # if we are are not on 5.10, cause 5.8 detects it
536 # late. This will do nothing if all is well, and
537 # blow up otherwise. Yes, it's an ugly hack, better
538 # suggestions are welcome.
540 ($name || return)->isa('This is a test for circular inheritance')
543 # if our mro is c3, we can
544 # just grab the linear_isa
545 if (mro::get_mro($name) eq 'c3') {
546 return @{ mro::get_linear_isa($name) }
550 # we can't grab the linear_isa for dfs
551 # since it has all the duplicates
556 $self->initialize($_)->class_precedence_list()
557 } $self->superclasses()
564 sub wrap_method_body {
565 my ( $self, %args ) = @_;
567 ('CODE' eq ref $args{body})
568 || confess "Your code block must be a CODE reference";
570 $self->method_metaclass->wrap(
571 package_name => $self->name,
577 my ($self, $method_name, $method) = @_;
578 (defined $method_name && $method_name)
579 || confess "You must define a method name";
582 if (blessed($method)) {
583 $body = $method->body;
584 if ($method->package_name ne $self->name) {
585 $method = $method->clone(
586 package_name => $self->name,
588 ) if $method->can('clone');
593 $method = $self->wrap_method_body( body => $body, name => $method_name );
596 $method->attach_to_class($self);
598 # This used to call get_method_map, which meant we would build all
599 # the method objects for the class just because we added one
600 # method. This is hackier, but quicker too.
601 $self->{methods}{$method_name} = $method;
603 my $full_method_name = ($self->name . '::' . $method_name);
604 $self->add_package_symbol(
605 { sigil => '&', type => 'CODE', name => $method_name },
606 Class::MOP::subname($full_method_name => $body)
611 my $fetch_and_prepare_method = sub {
612 my ($self, $method_name) = @_;
613 my $wrapped_metaclass = $self->wrapped_method_metaclass;
615 my $method = $self->get_method($method_name);
616 # if we dont have local ...
618 # try to find the next method
619 $method = $self->find_next_method_by_name($method_name);
620 # die if it does not exist
622 || confess "The method '$method_name' was not found in the inheritance hierarchy for " . $self->name;
623 # and now make sure to wrap it
624 # even if it is already wrapped
625 # because we need a new sub ref
626 $method = $wrapped_metaclass->wrap($method);
629 # now make sure we wrap it properly
630 $method = $wrapped_metaclass->wrap($method)
631 unless $method->isa($wrapped_metaclass);
633 $self->add_method($method_name => $method);
637 sub add_before_method_modifier {
638 my ($self, $method_name, $method_modifier) = @_;
639 (defined $method_name && $method_name)
640 || confess "You must pass in a method name";
641 my $method = $fetch_and_prepare_method->($self, $method_name);
642 $method->add_before_modifier(
643 Class::MOP::subname(':before' => $method_modifier)
647 sub add_after_method_modifier {
648 my ($self, $method_name, $method_modifier) = @_;
649 (defined $method_name && $method_name)
650 || confess "You must pass in a method name";
651 my $method = $fetch_and_prepare_method->($self, $method_name);
652 $method->add_after_modifier(
653 Class::MOP::subname(':after' => $method_modifier)
657 sub add_around_method_modifier {
658 my ($self, $method_name, $method_modifier) = @_;
659 (defined $method_name && $method_name)
660 || confess "You must pass in a method name";
661 my $method = $fetch_and_prepare_method->($self, $method_name);
662 $method->add_around_modifier(
663 Class::MOP::subname(':around' => $method_modifier)
668 # the methods above used to be named like this:
669 # ${pkg}::${method}:(before|after|around)
670 # but this proved problematic when using one modifier
671 # to wrap multiple methods (something which is likely
672 # to happen pretty regularly IMO). So instead of naming
673 # it like this, I have chosen to just name them purely
674 # with their modifier names, like so:
675 # :(before|after|around)
676 # The fact is that in a stack trace, it will be fairly
677 # evident from the context what method they are attached
678 # to, and so don't need the fully qualified name.
684 $self->add_method(@_);
688 my ($self, $method_name) = @_;
689 (defined $method_name && $method_name)
690 || confess "You must define a method name";
692 exists $self->{methods}{$method_name} || exists $self->get_method_map->{$method_name};
696 my ($self, $method_name) = @_;
697 (defined $method_name && $method_name)
698 || confess "You must define a method name";
700 return $self->{methods}{$method_name} || $self->get_method_map->{$method_name};
704 my ($self, $method_name) = @_;
705 (defined $method_name && $method_name)
706 || confess "You must define a method name";
708 my $removed_method = delete $self->get_method_map->{$method_name};
710 $self->remove_package_symbol(
711 { sigil => '&', type => 'CODE', name => $method_name }
714 $removed_method->detach_from_class if $removed_method;
716 $self->update_package_cache_flag; # still valid, since we just removed the method from the map
718 return $removed_method;
721 sub get_method_list {
723 keys %{$self->get_method_map};
726 sub find_method_by_name {
727 my ($self, $method_name) = @_;
728 (defined $method_name && $method_name)
729 || confess "You must define a method name to find";
730 foreach my $class ($self->linearized_isa) {
731 # fetch the meta-class ...
732 my $meta = $self->initialize($class);
733 return $meta->get_method($method_name)
734 if $meta->has_method($method_name);
739 sub get_all_methods {
741 my %methods = map { %{ $self->initialize($_)->get_method_map } } reverse $self->linearized_isa;
742 return values %methods;
746 sub compute_all_applicable_methods {
750 class => $_->package_name,
751 code => $_, # sigh, overloading
753 } shift->get_all_methods(@_);
756 sub get_all_method_names {
759 grep { $uniq{$_}++ == 0 } map { $_->name } $self->get_all_methods;
762 sub find_all_methods_by_name {
763 my ($self, $method_name) = @_;
764 (defined $method_name && $method_name)
765 || confess "You must define a method name to find";
767 foreach my $class ($self->linearized_isa) {
768 # fetch the meta-class ...
769 my $meta = $self->initialize($class);
771 name => $method_name,
773 code => $meta->get_method($method_name)
774 } if $meta->has_method($method_name);
779 sub find_next_method_by_name {
780 my ($self, $method_name) = @_;
781 (defined $method_name && $method_name)
782 || confess "You must define a method name to find";
783 my @cpl = $self->linearized_isa;
784 shift @cpl; # discard ourselves
785 foreach my $class (@cpl) {
786 # fetch the meta-class ...
787 my $meta = $self->initialize($class);
788 return $meta->get_method($method_name)
789 if $meta->has_method($method_name);
798 # either we have an attribute object already
799 # or we need to create one from the args provided
800 my $attribute = blessed($_[0]) ? $_[0] : $self->attribute_metaclass->new(@_);
801 # make sure it is derived from the correct type though
802 ($attribute->isa('Class::MOP::Attribute'))
803 || confess "Your attribute must be an instance of Class::MOP::Attribute (or a subclass)";
805 # first we attach our new attribute
806 # because it might need certain information
807 # about the class which it is attached to
808 $attribute->attach_to_class($self);
810 # then we remove attributes of a conflicting
811 # name here so that we can properly detach
812 # the old attr object, and remove any
813 # accessors it would have generated
814 if ( $self->has_attribute($attribute->name) ) {
815 $self->remove_attribute($attribute->name);
817 $self->invalidate_meta_instances();
820 # then onto installing the new accessors
821 $self->get_attribute_map->{$attribute->name} = $attribute;
823 # invalidate package flag here
824 my $e = do { local $@; eval { $attribute->install_accessors() }; $@ };
826 $self->remove_attribute($attribute->name);
833 sub update_meta_instance_dependencies {
836 if ( $self->{meta_instance_dependencies} ) {
837 return $self->add_meta_instance_dependencies;
841 sub add_meta_instance_dependencies {
844 $self->remove_meta_instance_dependencies;
846 my @attrs = $self->compute_all_applicable_attributes();
849 my @classes = grep { not $seen{$_->name}++ } map { $_->associated_class } @attrs;
851 foreach my $class ( @classes ) {
852 $class->add_dependent_meta_instance($self);
855 $self->{meta_instance_dependencies} = \@classes;
858 sub remove_meta_instance_dependencies {
861 if ( my $classes = delete $self->{meta_instance_dependencies} ) {
862 foreach my $class ( @$classes ) {
863 $class->remove_dependent_meta_instance($self);
873 sub add_dependent_meta_instance {
874 my ( $self, $metaclass ) = @_;
875 push @{ $self->{dependent_meta_instances} }, $metaclass;
878 sub remove_dependent_meta_instance {
879 my ( $self, $metaclass ) = @_;
880 my $name = $metaclass->name;
881 @$_ = grep { $_->name ne $name } @$_ for $self->{dependent_meta_instances};
884 sub invalidate_meta_instances {
886 $_->invalidate_meta_instance() for $self, @{ $self->{dependent_meta_instances} };
889 sub invalidate_meta_instance {
891 undef $self->{_meta_instance};
895 my ($self, $attribute_name) = @_;
896 (defined $attribute_name && $attribute_name)
897 || confess "You must define an attribute name";
898 exists $self->get_attribute_map->{$attribute_name};
902 my ($self, $attribute_name) = @_;
903 (defined $attribute_name && $attribute_name)
904 || confess "You must define an attribute name";
905 return $self->get_attribute_map->{$attribute_name}
907 # this will return undef anyway, so no need ...
908 # if $self->has_attribute($attribute_name);
912 sub remove_attribute {
913 my ($self, $attribute_name) = @_;
914 (defined $attribute_name && $attribute_name)
915 || confess "You must define an attribute name";
916 my $removed_attribute = $self->get_attribute_map->{$attribute_name};
917 return unless defined $removed_attribute;
918 delete $self->get_attribute_map->{$attribute_name};
919 $self->invalidate_meta_instances();
920 $removed_attribute->remove_accessors();
921 $removed_attribute->detach_from_class();
922 return $removed_attribute;
925 sub get_attribute_list {
927 keys %{$self->get_attribute_map};
930 sub get_all_attributes {
931 shift->compute_all_applicable_attributes(@_);
934 sub compute_all_applicable_attributes {
936 my %attrs = map { %{ $self->initialize($_)->get_attribute_map } } reverse $self->linearized_isa;
937 return values %attrs;
940 sub find_attribute_by_name {
941 my ($self, $attr_name) = @_;
942 foreach my $class ($self->linearized_isa) {
943 # fetch the meta-class ...
944 my $meta = $self->initialize($class);
945 return $meta->get_attribute($attr_name)
946 if $meta->has_attribute($attr_name);
951 # check if we can reinitialize
955 # if any local attr is defined
956 return if $self->get_attribute_list;
958 # or any non-declared methods
959 if ( my @methods = values %{ $self->get_method_map } ) {
960 my $metaclass = $self->method_metaclass;
961 foreach my $method ( @methods ) {
962 return if $method->isa("Class::MOP::Method::Generated");
963 # FIXME do we need to enforce this too? return unless $method->isa($metaclass);
973 sub is_immutable { 0 }
975 sub immutable_transformer { $_[0]->{immutable_transformer} }
976 sub _set_immutable_transformer { $_[0]->{immutable_transformer} = $_[1] }
979 my %Default_Immutable_Options = (
980 read_only => [qw/superclasses/],
988 remove_package_symbol
992 class_precedence_list => 'ARRAY',
993 # FIXME perl 5.10 memoizes this on its own, no need?
994 linearized_isa => 'ARRAY',
995 get_all_methods => 'ARRAY',
996 get_all_method_names => 'ARRAY',
997 compute_all_applicable_attributes => 'ARRAY',
998 get_meta_instance => 'SCALAR',
999 get_method_map => 'SCALAR',
1003 # this is ugly, but so are typeglobs,
1004 # so whattayahgonnadoboutit
1007 add_package_symbol => sub {
1008 my $original = shift;
1009 confess "Cannot add package symbols to an immutable metaclass"
1010 unless ( caller(2) )[3] eq
1011 'Class::MOP::Package::get_package_symbol';
1013 # This is a workaround for a bug in 5.8.1 which thinks that
1014 # goto $original->body
1015 # is trying to go to a label
1016 my $body = $original->body;
1022 sub make_immutable {
1025 return if $self->is_immutable;
1027 my $transformer = $self->immutable_transformer
1028 || Class::MOP::Immutable->new(
1030 %Default_Immutable_Options,
1034 $self->_set_immutable_transformer($transformer);
1036 $transformer->make_metaclass_immutable;
1043 return if $self->is_mutable;
1045 $self->immutable_transformer->make_metaclass_mutable;
1056 Class::MOP::Class - Class Meta Object
1060 # assuming that class Foo
1061 # has been defined, you can
1063 # use this for introspection ...
1065 # add a method to Foo ...
1066 Foo->meta->add_method( 'bar' => sub {...} )
1068 # get a list of all the classes searched
1069 # the method dispatcher in the correct order
1070 Foo->meta->class_precedence_list()
1072 # remove a method from Foo
1073 Foo->meta->remove_method('bar');
1075 # or use this to actually create classes ...
1077 Class::MOP::Class->create(
1080 superclasses => ['Foo'],
1082 Class::MOP:: : Attribute->new('$bar'),
1083 Class::MOP:: : Attribute->new('$baz'),
1086 calculate_bar => sub {...},
1087 construct_baz => sub {...}
1094 This is the largest and most complex part of the Class::MOP
1095 meta-object protocol. It controls the introspection and manipulation
1096 of Perl 5 classes, and it can create them as wlel. The best way to
1097 understand what this module can do, is to read the documentation for
1098 each of its methods.
1102 C<Class::MOP::Class> is a subclass of L<Class::MOP::Module>.
1106 =head2 Class construction
1108 These methods all create new C<Class::MOP::Class> objects. These
1109 objects can represent existing classes, or they can be used to create
1110 new classes from scratch.
1112 The metaclass object for a given class is a singleton. If you attempt
1113 to create a metaclass for the same class twice, you will just get the
1118 =item B<< Class::MOP::Class->create($package_name, %options) >>
1120 This method creates a new C<Class::MOP::Class> object with the given
1121 package name. It accepts a number of options.
1127 An optional version number for the newly created package.
1131 An optional authority for the newly created package.
1133 =item * superclasses
1135 An optional array reference of superclass names.
1139 An optional hash reference of methods for the class. The keys of the
1140 hash reference are method names, and values are subroutine references.
1144 An optional array reference of attributes.
1146 An attribute can be passed as an existing L<Class::MOP::Attribute>
1147 object, I<or> or as a hash reference of options which will be passed
1148 to the attribute metaclass's constructor.
1152 =item B<< Class::MOP::Class->create_anon_class(%options) >>
1154 This method works just like C<< Class::MOP::Class->create >> but it
1155 creates an "anonymous" class. In fact, the class does have a name, but
1156 that name is a unique name generated internally by this module.
1158 It accepts the same C<superclasses>, C<methods>, and C<attributes>
1159 parameters that C<create> accepts.
1161 Anonymous classes are destroyed once the metaclass they are attached
1162 to goes out of scope, and will be removed from Perl's internal symbol
1165 All instances of an anonymous class keep a special reference to the
1166 metaclass object, which prevents the metaclass from going out of scope
1167 while any instances exist.
1169 This only works if the instance if based on a hash reference, however.
1171 =item B<< Class::MOP::Class->initialize($package_name, %options) >>
1173 This method will initialize a C<Class::MOP::Class> object for the
1174 named package. Unlike C<create>, this method I<will not> create a new
1177 The purpose of this method is to retrieve a C<Class::MOP::Class>
1178 object for introspecting an existing class.
1180 If an existing C<Class::MOP::Class> object exists for the named
1181 package, it will be returned, and any options provided will be
1184 If the object does not yet exist, it will be created.
1186 The valid options that can be passed to this method are
1187 C<attribute_metaclass>, C<method_metaclass>,
1188 C<wrapped_method_metaclass>, and C<instance_metaclass>. These are all
1189 optional, and default to the appropriate class in the C<Class::MOP>
1194 =head2 Object instance construction and cloning
1196 These methods are all related to creating and/or cloning object
1201 =item B<< $metaclass->clone_object($instance, %params) >>
1203 This method clones an existing object instance. Any parameters you
1204 provide are will override existing attribute values in the object.
1206 This is a convience method for cloning an object instance, then
1207 blessing it into the appropriate package.
1209 You could implement a clone method in your class, using this method:
1212 my ($self, %params) = @_;
1213 $self->meta->clone_object($self, %params);
1216 =item B<< $metaclass->rebless_instance($instance, %params) >>
1218 This method changes the class of C<$instance> to the metaclass's class.
1220 You can only rebless an instance into a subclass of its current
1221 class. If you pass any additional parameters, these will be treated
1222 like constructor parameters and used to initialize the object's
1223 attributes. Any existing attributes that are already set will be
1226 =item B<< $metaclass->new_object(%params) >>
1228 This method is used to create a new object of the metaclass's
1229 class. Any parameters you provide are used to initialize the
1230 instance's attributes.
1232 =item B<< $metaclass->instance_metaclass >>
1234 Returns the class name of the instance metaclass, see
1235 L<Class::MOP::Instance> for more information on the instance
1238 =item B<< $metaclass->get_meta_instance >>
1240 Returns an instance of the C<instance_metaclass> to be used in the
1241 construction of a new instance of the class.
1245 =head2 Informational predicates
1247 These are a few predicate methods for asking information about the
1252 =item B<< $metaclass->is_anon_class >>
1254 This returns true if the class was created by calling C<<
1255 Class::MOP::Class->create_anon_class >>.
1257 =item B<< $metaclass->is_mutable >>
1259 This returns true if the class is still mutable.
1261 =item B<< $metaclass->is_immutable >>
1263 This returns true if the class has been made immutable.
1265 =item B<< $metaclass->is_pristine >>
1267 A class is I<not> pristine if it has non-inherited attributes or if it
1268 has any generated methods.
1272 =head2 Inheritance Relationships
1276 =item B<< $metaclass->superclasses(@superclasses) >>
1278 This is a read-write accessor which represents the superclass
1279 relationships of the metaclass's class.
1281 This is basically sugar around getting and setting C<@ISA>.
1283 =item B<< $metaclass->class_precedence_list >>
1285 This returns a list of all of the class's ancestor classes. The
1286 classes are returned in method dispatch order.
1288 =item B<< $metaclass->linearized_isa >>
1290 This returns a list based on C<class_precedence_list> but with all
1293 =item B<< $metaclass->subclasses >>
1295 This returns a list of subclasses for this class.
1299 =head2 Method introspection and creation
1301 These methods allow you to introspect a class's methods, as well as
1302 add, remove, or change methods.
1304 Determining what is truly a method in a Perl 5 class requires some
1305 heuristics (aka guessing).
1307 Methods defined outside the package with a fully qualified name (C<sub
1308 Package::name { ... }>) will be included. Similarly, methods named
1309 with a fully qualified name using L<Sub::Name> are also included.
1311 However, we attempt to ignore imported functions.
1313 Ultimately, we are using heuristics to determine what truly is a
1314 method in a class, and these heuristics may get the wrong answer in
1315 some edge cases. However, for most "normal" cases the heuristics work
1320 =item B<< $metaclass->get_method($method_name) >>
1322 This will return a L<Class::MOP::Method> for the specified
1323 C<$method_name>. If the class does not have the specified method, it
1326 =item B<< $metaclass->has_method($method_name) >>
1328 Returns a boolean indicating whether or not the class defines the
1329 named method. It does not include methods inherited from parent
1332 =item B<< $metaclass->get_method_map >>
1334 Returns a hash reference representing the methods defined in this
1335 class. The keys are method names and the values are
1336 L<Class::MOP::Method> objects.
1338 =item B<< $metaclass->get_method_list >>
1340 This will return a list of method I<names> for all methods defined in
1343 =item B<< $metaclass->get_all_methods >>
1345 This will traverse the inheritance hierarchy and return a list of all
1346 the L<Class::MOP::Method> objects for this class and its parents.
1348 =item B<< $metaclass->find_method_by_name($method_name) >>
1350 This will return a L<Class::MOP::Method> for the specified
1351 C<$method_name>. If the class does not have the specified method, it
1354 Unlike C<get_method>, this method I<will> look for the named method in
1357 =item B<< $metaclass->get_all_method_names >>
1359 This will return a list of method I<names> for all of this class's
1360 methods, including inherited methods.
1362 =item B<< $metaclass->find_all_methods_by_name($method_name) >>
1364 This method looks for the named method in the class and all of its
1365 parents. It returns every matching method it finds in the inheritance
1366 tree, so it returns a list of methods.
1368 Each method is returned as a hash reference with three keys. The keys
1369 are C<name>, C<class>, and C<code>. The C<code> key has a
1370 L<Class::MOP::Method> object as its value.
1372 The list of methods is distinct.
1374 =item B<< $metaclass->find_next_method_by_name($method_name) >>
1376 This method returns the first method in any superclass matching the
1377 given name. It is effectively the method that C<SUPER::$method_name>
1380 =item B<< $metaclass->add_method($method_name, $method) >>
1382 This method takes a method name and a subroutine reference, and adds
1383 the method to the class.
1385 The subroutine reference can be a L<Class::MOP::Method>, and you are
1386 strongly encouraged to pass a meta method object instead of a code
1387 reference. If you do so, that object gets stored as part of the
1388 class's method map directly. If not, the meta information will have to
1389 be recreated later, and may be incorrect.
1391 If you provide a method object, this method will clone that object if
1392 the object's package name does not match the class name. This lets us
1393 track the original source of any methods added from other classes
1394 (notably Moose roles).
1396 =item B<< $metaclass->remove_method($method_name) >>
1398 Remove the named method from the class. This method returns the
1399 L<Class::MOP::Method> object for the method.
1403 =head2 Attribute introspection and creation
1405 Because Perl 5 does not have a core concept of attributes in classes,
1406 we can only return information about attributes which have been added
1407 via this class's methods. We cannot discover information about
1408 attributes which are defined in terms of "regular" Perl 5 methods.
1412 =item B<< $metaclass->get_attribute($attribute_name) >>
1414 This will return a L<Class::MOP::Attribute> for the specified
1415 C<$attribute_name>. If the class does not have the specified
1416 attribute, it returns C<undef>
1418 =item B<< $metaclass->has_attribute($attribute_name) >>
1420 Returns a boolean indicating whether or not the class defines the
1421 named attribute. It does not include attributes inherited from parent
1424 =item B<< $metaclass->get_attribute_map >>
1426 Returns a hash reference representing the attributes defined in this
1427 class. The keys are attribute names and the values are
1428 L<Class::MOP::Attribute> objects.
1430 =item B<< $metaclass->get_attribute_list >>
1432 This will return a list of attributes I<names> for all attributes
1433 defined in this class.
1435 =item B<< $metaclass->get_all_attributes >>
1437 This will traverse the inheritance hierarchy and return a list of all
1438 the L<Class::MOP::Attribute> objects for this class and its parents.
1440 This method can also be called as C<compute_all_applicable_attributes>.
1442 =item B<< $metaclass->find_attribute_by_name($attribute_name) >>
1444 This will return a L<Class::MOP::Attribute> for the specified
1445 C<$attribute_name>. If the class does not have the specified
1446 attribute, it returns C<undef>
1448 Unlike C<get_attribute>, this attribute I<will> look for the named
1449 attribute in superclasses.
1451 =item B<< $metaclass->add_attribute(...) >>
1453 This method accepts either an existing L<Class::MOP::Attribute>
1454 object, or parameters suitable for passing to that class's C<new>
1457 The attribute provided will be added to the class.
1459 Any accessor methods defined by the attribute will be added to the
1460 class when the attribute is added.
1462 If an attribute of the same name already exists, the old attribute
1463 will be removed first.
1465 =item B<< $metaclass->remove_attribute($attribute_name) >>
1467 This will remove the named attribute from the class, and
1468 L<Class::MOP::Attribute> object.
1470 Removing an attribute also removes any accessor methods defined by the
1473 However, note that removing an attribute will only affect I<future>
1474 object instances created for this class, not existing instances.
1476 =item B<< $metaclass->attribute_metaclass >>
1478 Returns the class name of the attribute metaclass for this class. By
1479 default, this is L<Class::MOP::Attribute>. for more information on
1483 =head2 Class Immutability
1485 Making a class immutable "freezes" the class definition. You can no
1486 longer call methods which alter the class, such as adding or removing
1487 methods or attributes.
1489 Making a class immutable lets us optimize the class by inlning some
1490 methods, and also allows us to optimize some methods on the metaclass
1493 The immutabilization system in L<Moose> takes much greater advantage
1494 of the inlining features than Class::MOP itself does.
1498 =item B<< $metaclass->make_immutable(%options) >>
1500 This method will create an immutable transformer and uses it to make
1501 the class and its metaclass object immutable.
1503 Details of how immutabilization works are in L<Class::MOP::Immutable>
1506 =item B<< $metaclass->make_mutable >>
1508 Calling this method reverse the immutabilization transformation.
1510 =item B<< $metaclass->immutable_transformer >>
1512 If the class has been made immutable previously, this returns the
1513 L<Class::MOP::Immutable> object that was created to do the
1516 If the class was never made immutable, this method will die.
1520 =head2 Method Modifiers
1522 Method modifiers are hooks which allow a method to be wrapped with
1523 I<before>, I<after> and I<around> method modifiers. Every time a
1524 method is called, it's modifiers are also called.
1526 A class can modify its own methods, as well as methods defined in
1529 =head3 How method modifiers work?
1531 Method modifiers work by wrapping the original method and then
1532 replacing it in the class's symbol table. The wrappers will handle
1533 calling all the modifiers in the appropariate orders and preserving
1534 the calling context for the original method.
1536 The return values of C<before> and C<after> modifiers are
1537 ignored. This is because their purpose is B<not> to filter the input
1538 and output of the primary method (this is done with an I<around>
1541 This may seem like an odd restriction to some, but doing this allows
1542 for simple code to be added at the beginning or end of a method call
1543 without altering the function of the wrapped method or placing any
1544 extra responsibility on the code of the modifier.
1546 Of course if you have more complex needs, you can use the C<around>
1547 modifier which allows you to change both the parameters passed to the
1548 wrapped method, as well as its return value.
1550 Before and around modifiers are called in last-defined-first-called
1551 order, while after modifiers are called in first-defined-first-called
1552 order. So the call tree might looks something like this:
1564 =head3 What is the performance impact?
1566 Of course there is a performance cost associated with method
1567 modifiers, but we have made every effort to make that cost directly
1568 proportional to the number of modifier features you utilize.
1570 The wrapping method does it's best to B<only> do as much work as it
1571 absolutely needs to. In order to do this we have moved some of the
1572 performance costs to set-up time, where they are easier to amortize.
1574 All this said, our benchmarks have indicated the following:
1576 simple wrapper with no modifiers 100% slower
1577 simple wrapper with simple before modifier 400% slower
1578 simple wrapper with simple after modifier 450% slower
1579 simple wrapper with simple around modifier 500-550% slower
1580 simple wrapper with all 3 modifiers 1100% slower
1582 These numbers may seem daunting, but you must remember, every feature
1583 comes with some cost. To put things in perspective, just doing a
1584 simple C<AUTOLOAD> which does nothing but extract the name of the
1585 method called and return it costs about 400% over a normal method
1590 =item B<< $metaclass->add_before_method_modifier($method_name, $code) >>
1592 This wraps the specified method with the supplied subroutine
1593 reference. The modifier will be called as a method itself, and will
1594 receive the same arguments as are passed to the method.
1596 When the modifier exits, the wrapped method will be called.
1598 The return value of the modifier will be ignored.
1600 =item B<< $metaclass->add_after_method_modifier($method_name, $code) >>
1602 This wraps the specified method with the supplied subroutine
1603 reference. The modifier will be called as a method itself, and will
1604 receive the same arguments as are passed to the method.
1606 When the wrapped methods exits, the modifier will be called.
1608 The return value of the modifier will be ignored.
1610 =item B<< $metaclass->add_around_method_modifier($method_name, $code) >>
1612 This wraps the specified method with the supplied subroutine
1615 The first argument passed to the modifier will be a subroutine
1616 reference to the wrapped method. The second argument is the object,
1617 and after that come any arguments passed when the method is called.
1619 The around modifier can choose to call the original method, as well as
1620 what arguments to pass if it does so.
1622 The return value of the modifier is what will be seen by the caller.
1628 Stevan Little E<lt>stevan@iinteractive.comE<gt>
1630 =head1 COPYRIGHT AND LICENSE
1632 Copyright 2006-2009 by Infinity Interactive, Inc.
1634 L<http://www.iinteractive.com>
1636 This library is free software; you can redistribute it and/or modify
1637 it under the same terms as Perl itself.