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 {
375 warn 'The create_meta_instance method has been made private.'
376 . " The public version is deprecated and will be removed in a future release.\n";
377 goto &_create_meta_instance;
380 sub _create_meta_instance {
383 my $instance = $self->instance_metaclass->new(
384 associated_metaclass => $self,
385 attributes => [ $self->compute_all_applicable_attributes() ],
388 $self->add_meta_instance_dependencies()
389 if $instance->is_dependent_on_superclasses();
396 my $instance = shift;
397 (blessed($instance) && $instance->isa($class->name))
398 || confess "You must pass an instance of the metaclass (" . (ref $class ? $class->name : $class) . "), not ($instance)";
401 # we need to protect the integrity of the
402 # Class::MOP::Class singletons here, they
403 # should not be cloned.
404 return $instance if $instance->isa('Class::MOP::Class');
405 $class->clone_instance($instance, @_);
409 my ($class, $instance, %params) = @_;
411 || confess "You can only clone instances, ($instance) is not a blessed instance";
412 my $meta_instance = $class->get_meta_instance();
413 my $clone = $meta_instance->clone_instance($instance);
414 foreach my $attr ($class->compute_all_applicable_attributes()) {
415 if ( defined( my $init_arg = $attr->init_arg ) ) {
416 if (exists $params{$init_arg}) {
417 $attr->set_value($clone, $params{$init_arg});
424 sub rebless_instance {
425 my ($self, $instance, %params) = @_;
428 if ($instance->can('meta')) {
429 ($instance->meta->isa('Class::MOP::Class'))
430 || confess 'Cannot rebless instance if ->meta is not an instance of Class::MOP::Class';
431 $old_metaclass = $instance->meta;
434 $old_metaclass = $self->initialize(ref($instance));
437 my $meta_instance = $self->get_meta_instance();
439 $self->name->isa($old_metaclass->name)
440 || confess "You may rebless only into a subclass of (". $old_metaclass->name ."), of which (". $self->name .") isn't.";
443 # we use $_[1] here because of t/306_rebless_overload.t regressions on 5.8.8
444 $meta_instance->rebless_instance_structure($_[1], $self);
446 foreach my $attr ( $self->compute_all_applicable_attributes ) {
447 if ( $attr->has_value($instance) ) {
448 if ( defined( my $init_arg = $attr->init_arg ) ) {
449 $params{$init_arg} = $attr->get_value($instance)
450 unless exists $params{$init_arg};
453 $attr->set_value($instance, $attr->get_value($instance));
458 foreach my $attr ($self->compute_all_applicable_attributes) {
459 $attr->initialize_instance_slot($meta_instance, $instance, \%params);
469 my $var_spec = { sigil => '@', type => 'ARRAY', name => 'ISA' };
472 @{$self->get_package_symbol($var_spec)} = @supers;
475 # on 5.8 and below, we need to call
476 # a method to get Perl to detect
477 # a cycle in the class hierarchy
478 my $class = $self->name;
482 # we need to check the metaclass
483 # compatibility here so that we can
484 # be sure that the superclass is
485 # not potentially creating an issues
486 # we don't know about
488 $self->_check_metaclass_compatibility();
489 $self->update_meta_instance_dependencies();
491 @{$self->get_package_symbol($var_spec)};
497 my $super_class = $self->name;
499 if ( Class::MOP::HAVE_ISAREV() ) {
500 return @{ $super_class->mro::get_isarev() };
504 my $find_derived_classes;
505 $find_derived_classes = sub {
506 my ($outer_class) = @_;
508 my $symbol_table_hashref = do { no strict 'refs'; \%{"${outer_class}::"} };
511 for my $symbol ( keys %$symbol_table_hashref ) {
512 next SYMBOL if $symbol !~ /\A (\w+):: \z/x;
513 my $inner_class = $1;
515 next SYMBOL if $inner_class eq 'SUPER'; # skip '*::SUPER'
519 ? "${outer_class}::$inner_class"
522 if ( $class->isa($super_class) and $class ne $super_class ) {
523 push @derived_classes, $class;
526 next SYMBOL if $class eq 'main'; # skip 'main::*'
528 $find_derived_classes->($class);
532 my $root_class = q{};
533 $find_derived_classes->($root_class);
535 undef $find_derived_classes;
537 @derived_classes = sort { $a->isa($b) ? 1 : $b->isa($a) ? -1 : 0 } @derived_classes;
539 return @derived_classes;
545 return @{ mro::get_linear_isa( (shift)->name ) };
548 sub class_precedence_list {
550 my $name = $self->name;
552 unless (Class::MOP::IS_RUNNING_ON_5_10()) {
554 # We need to check for circular inheritance here
555 # if we are are not on 5.10, cause 5.8 detects it
556 # late. This will do nothing if all is well, and
557 # blow up otherwise. Yes, it's an ugly hack, better
558 # suggestions are welcome.
560 ($name || return)->isa('This is a test for circular inheritance')
563 # if our mro is c3, we can
564 # just grab the linear_isa
565 if (mro::get_mro($name) eq 'c3') {
566 return @{ mro::get_linear_isa($name) }
570 # we can't grab the linear_isa for dfs
571 # since it has all the duplicates
576 $self->initialize($_)->class_precedence_list()
577 } $self->superclasses()
584 sub wrap_method_body {
585 my ( $self, %args ) = @_;
587 ('CODE' eq ref $args{body})
588 || confess "Your code block must be a CODE reference";
590 $self->method_metaclass->wrap(
591 package_name => $self->name,
597 my ($self, $method_name, $method) = @_;
598 (defined $method_name && $method_name)
599 || confess "You must define a method name";
602 if (blessed($method)) {
603 $body = $method->body;
604 if ($method->package_name ne $self->name) {
605 $method = $method->clone(
606 package_name => $self->name,
608 ) if $method->can('clone');
613 $method = $self->wrap_method_body( body => $body, name => $method_name );
616 $method->attach_to_class($self);
618 # This used to call get_method_map, which meant we would build all
619 # the method objects for the class just because we added one
620 # method. This is hackier, but quicker too.
621 $self->{methods}{$method_name} = $method;
623 my $full_method_name = ($self->name . '::' . $method_name);
624 $self->add_package_symbol(
625 { sigil => '&', type => 'CODE', name => $method_name },
626 Class::MOP::subname($full_method_name => $body)
631 my $fetch_and_prepare_method = sub {
632 my ($self, $method_name) = @_;
633 my $wrapped_metaclass = $self->wrapped_method_metaclass;
635 my $method = $self->get_method($method_name);
636 # if we dont have local ...
638 # try to find the next method
639 $method = $self->find_next_method_by_name($method_name);
640 # die if it does not exist
642 || confess "The method '$method_name' was not found in the inheritance hierarchy for " . $self->name;
643 # and now make sure to wrap it
644 # even if it is already wrapped
645 # because we need a new sub ref
646 $method = $wrapped_metaclass->wrap($method);
649 # now make sure we wrap it properly
650 $method = $wrapped_metaclass->wrap($method)
651 unless $method->isa($wrapped_metaclass);
653 $self->add_method($method_name => $method);
657 sub add_before_method_modifier {
658 my ($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_before_modifier(
663 Class::MOP::subname(':before' => $method_modifier)
667 sub add_after_method_modifier {
668 my ($self, $method_name, $method_modifier) = @_;
669 (defined $method_name && $method_name)
670 || confess "You must pass in a method name";
671 my $method = $fetch_and_prepare_method->($self, $method_name);
672 $method->add_after_modifier(
673 Class::MOP::subname(':after' => $method_modifier)
677 sub add_around_method_modifier {
678 my ($self, $method_name, $method_modifier) = @_;
679 (defined $method_name && $method_name)
680 || confess "You must pass in a method name";
681 my $method = $fetch_and_prepare_method->($self, $method_name);
682 $method->add_around_modifier(
683 Class::MOP::subname(':around' => $method_modifier)
688 # the methods above used to be named like this:
689 # ${pkg}::${method}:(before|after|around)
690 # but this proved problematic when using one modifier
691 # to wrap multiple methods (something which is likely
692 # to happen pretty regularly IMO). So instead of naming
693 # it like this, I have chosen to just name them purely
694 # with their modifier names, like so:
695 # :(before|after|around)
696 # The fact is that in a stack trace, it will be fairly
697 # evident from the context what method they are attached
698 # to, and so don't need the fully qualified name.
704 $self->add_method(@_);
708 my ($self, $method_name) = @_;
709 (defined $method_name && $method_name)
710 || confess "You must define a method name";
712 exists $self->{methods}{$method_name} || exists $self->get_method_map->{$method_name};
716 my ($self, $method_name) = @_;
717 (defined $method_name && $method_name)
718 || confess "You must define a method name";
720 return $self->{methods}{$method_name} || $self->get_method_map->{$method_name};
724 my ($self, $method_name) = @_;
725 (defined $method_name && $method_name)
726 || confess "You must define a method name";
728 my $removed_method = delete $self->get_method_map->{$method_name};
730 $self->remove_package_symbol(
731 { sigil => '&', type => 'CODE', name => $method_name }
734 $removed_method->detach_from_class if $removed_method;
736 $self->update_package_cache_flag; # still valid, since we just removed the method from the map
738 return $removed_method;
741 sub get_method_list {
743 keys %{$self->get_method_map};
746 sub find_method_by_name {
747 my ($self, $method_name) = @_;
748 (defined $method_name && $method_name)
749 || confess "You must define a method name to find";
750 foreach my $class ($self->linearized_isa) {
751 # fetch the meta-class ...
752 my $meta = $self->initialize($class);
753 return $meta->get_method($method_name)
754 if $meta->has_method($method_name);
759 sub get_all_methods {
761 my %methods = map { %{ $self->initialize($_)->get_method_map } } reverse $self->linearized_isa;
762 return values %methods;
766 sub compute_all_applicable_methods {
770 class => $_->package_name,
771 code => $_, # sigh, overloading
773 } shift->get_all_methods(@_);
776 sub get_all_method_names {
779 grep { $uniq{$_}++ == 0 } map { $_->name } $self->get_all_methods;
782 sub find_all_methods_by_name {
783 my ($self, $method_name) = @_;
784 (defined $method_name && $method_name)
785 || confess "You must define a method name to find";
787 foreach my $class ($self->linearized_isa) {
788 # fetch the meta-class ...
789 my $meta = $self->initialize($class);
791 name => $method_name,
793 code => $meta->get_method($method_name)
794 } if $meta->has_method($method_name);
799 sub find_next_method_by_name {
800 my ($self, $method_name) = @_;
801 (defined $method_name && $method_name)
802 || confess "You must define a method name to find";
803 my @cpl = $self->linearized_isa;
804 shift @cpl; # discard ourselves
805 foreach my $class (@cpl) {
806 # fetch the meta-class ...
807 my $meta = $self->initialize($class);
808 return $meta->get_method($method_name)
809 if $meta->has_method($method_name);
818 # either we have an attribute object already
819 # or we need to create one from the args provided
820 my $attribute = blessed($_[0]) ? $_[0] : $self->attribute_metaclass->new(@_);
821 # make sure it is derived from the correct type though
822 ($attribute->isa('Class::MOP::Attribute'))
823 || confess "Your attribute must be an instance of Class::MOP::Attribute (or a subclass)";
825 # first we attach our new attribute
826 # because it might need certain information
827 # about the class which it is attached to
828 $attribute->attach_to_class($self);
830 # then we remove attributes of a conflicting
831 # name here so that we can properly detach
832 # the old attr object, and remove any
833 # accessors it would have generated
834 if ( $self->has_attribute($attribute->name) ) {
835 $self->remove_attribute($attribute->name);
837 $self->invalidate_meta_instances();
840 # then onto installing the new accessors
841 $self->get_attribute_map->{$attribute->name} = $attribute;
843 # invalidate package flag here
844 my $e = do { local $@; eval { $attribute->install_accessors() }; $@ };
846 $self->remove_attribute($attribute->name);
853 sub update_meta_instance_dependencies {
856 if ( $self->{meta_instance_dependencies} ) {
857 return $self->add_meta_instance_dependencies;
861 sub add_meta_instance_dependencies {
864 $self->remove_meta_instance_dependencies;
866 my @attrs = $self->compute_all_applicable_attributes();
869 my @classes = grep { not $seen{$_->name}++ } map { $_->associated_class } @attrs;
871 foreach my $class ( @classes ) {
872 $class->add_dependent_meta_instance($self);
875 $self->{meta_instance_dependencies} = \@classes;
878 sub remove_meta_instance_dependencies {
881 if ( my $classes = delete $self->{meta_instance_dependencies} ) {
882 foreach my $class ( @$classes ) {
883 $class->remove_dependent_meta_instance($self);
893 sub add_dependent_meta_instance {
894 my ( $self, $metaclass ) = @_;
895 push @{ $self->{dependent_meta_instances} }, $metaclass;
898 sub remove_dependent_meta_instance {
899 my ( $self, $metaclass ) = @_;
900 my $name = $metaclass->name;
901 @$_ = grep { $_->name ne $name } @$_ for $self->{dependent_meta_instances};
904 sub invalidate_meta_instances {
906 $_->invalidate_meta_instance() for $self, @{ $self->{dependent_meta_instances} };
909 sub invalidate_meta_instance {
911 undef $self->{_meta_instance};
915 my ($self, $attribute_name) = @_;
916 (defined $attribute_name && $attribute_name)
917 || confess "You must define an attribute name";
918 exists $self->get_attribute_map->{$attribute_name};
922 my ($self, $attribute_name) = @_;
923 (defined $attribute_name && $attribute_name)
924 || confess "You must define an attribute name";
925 return $self->get_attribute_map->{$attribute_name}
927 # this will return undef anyway, so no need ...
928 # if $self->has_attribute($attribute_name);
932 sub remove_attribute {
933 my ($self, $attribute_name) = @_;
934 (defined $attribute_name && $attribute_name)
935 || confess "You must define an attribute name";
936 my $removed_attribute = $self->get_attribute_map->{$attribute_name};
937 return unless defined $removed_attribute;
938 delete $self->get_attribute_map->{$attribute_name};
939 $self->invalidate_meta_instances();
940 $removed_attribute->remove_accessors();
941 $removed_attribute->detach_from_class();
942 return $removed_attribute;
945 sub get_attribute_list {
947 keys %{$self->get_attribute_map};
950 sub get_all_attributes {
951 shift->compute_all_applicable_attributes(@_);
954 sub compute_all_applicable_attributes {
956 my %attrs = map { %{ $self->initialize($_)->get_attribute_map } } reverse $self->linearized_isa;
957 return values %attrs;
960 sub find_attribute_by_name {
961 my ($self, $attr_name) = @_;
962 foreach my $class ($self->linearized_isa) {
963 # fetch the meta-class ...
964 my $meta = $self->initialize($class);
965 return $meta->get_attribute($attr_name)
966 if $meta->has_attribute($attr_name);
971 # check if we can reinitialize
975 # if any local attr is defined
976 return if $self->get_attribute_list;
978 # or any non-declared methods
979 if ( my @methods = values %{ $self->get_method_map } ) {
980 my $metaclass = $self->method_metaclass;
981 foreach my $method ( @methods ) {
982 return if $method->isa("Class::MOP::Method::Generated");
983 # FIXME do we need to enforce this too? return unless $method->isa($metaclass);
993 sub is_immutable { 0 }
996 # Why I changed this (groditi)
997 # - One Metaclass may have many Classes through many Metaclass instances
998 # - One Metaclass should only have one Immutable Transformer instance
999 # - Each Class may have different Immutabilizing options
1000 # - Therefore each Metaclass instance may have different Immutabilizing options
1001 # - We need to store one Immutable Transformer instance per Metaclass
1002 # - We need to store one set of Immutable Transformer options per Class
1003 # - Upon make_mutable we may delete the Immutabilizing options
1004 # - We could clean the immutable Transformer instance when there is no more
1005 # immutable Classes of that type, but we can also keep it in case
1006 # another class with this same Metaclass becomes immutable. It is a case
1007 # of trading of storing an instance to avoid unnecessary instantiations of
1008 # Immutable Transformers. You may view this as a memory leak, however
1009 # Because we have few Metaclasses, in practice it seems acceptable
1010 # - To allow Immutable Transformers instances to be cleaned up we could weaken
1011 # the reference stored in $IMMUTABLE_TRANSFORMERS{$class} and ||= should DWIM
1015 my %IMMUTABLE_TRANSFORMERS;
1016 my %IMMUTABLE_OPTIONS;
1018 sub get_immutable_options {
1020 return if $self->is_mutable;
1021 confess "unable to find immutabilizing options"
1022 unless exists $IMMUTABLE_OPTIONS{$self->name};
1023 my %options = %{$IMMUTABLE_OPTIONS{$self->name}};
1024 delete $options{IMMUTABLE_TRANSFORMER};
1028 sub get_immutable_transformer {
1030 if( $self->is_mutable ){
1031 return $IMMUTABLE_TRANSFORMERS{$self->name} ||= $self->create_immutable_transformer;
1033 confess "unable to find transformer for immutable class"
1034 unless exists $IMMUTABLE_OPTIONS{$self->name};
1035 return $IMMUTABLE_OPTIONS{$self->name}->{IMMUTABLE_TRANSFORMER};
1038 sub make_immutable {
1042 my $transformer = $self->get_immutable_transformer;
1043 $transformer->make_metaclass_immutable($self, \%options);
1044 $IMMUTABLE_OPTIONS{$self->name} =
1045 { %options, IMMUTABLE_TRANSFORMER => $transformer };
1047 if( exists $options{debug} && $options{debug} ){
1048 print STDERR "# of Metaclass options: ", keys %IMMUTABLE_OPTIONS;
1049 print STDERR "# of Immutable transformers: ", keys %IMMUTABLE_TRANSFORMERS;
1057 return if $self->is_mutable;
1058 my $options = delete $IMMUTABLE_OPTIONS{$self->name};
1059 confess "unable to find immutabilizing options" unless ref $options;
1060 my $transformer = delete $options->{IMMUTABLE_TRANSFORMER};
1061 $transformer->make_metaclass_mutable($self, $options);
1066 sub create_immutable_transformer {
1068 my $class = Class::MOP::Immutable->new($self, {
1069 read_only => [qw/superclasses/],
1076 remove_package_symbol
1079 class_precedence_list => 'ARRAY',
1080 linearized_isa => 'ARRAY', # FIXME perl 5.10 memoizes this on its own, no need?
1081 get_all_methods => 'ARRAY',
1082 get_all_method_names => 'ARRAY',
1083 #get_all_attributes => 'ARRAY', # it's an alias, no need, but maybe in the future
1084 compute_all_applicable_attributes => 'ARRAY',
1085 get_meta_instance => 'SCALAR',
1086 get_method_map => 'SCALAR',
1089 # this is ugly, but so are typeglobs,
1090 # so whattayahgonnadoboutit
1093 add_package_symbol => sub {
1094 my $original = shift;
1095 confess "Cannot add package symbols to an immutable metaclass"
1096 unless (caller(2))[3] eq 'Class::MOP::Package::get_package_symbol';
1098 # This is a workaround for a bug in 5.8.1 which thinks that
1099 # goto $original->body
1100 # is trying to go to a label
1101 my $body = $original->body;
1117 Class::MOP::Class - Class Meta Object
1121 # assuming that class Foo
1122 # has been defined, you can
1124 # use this for introspection ...
1126 # add a method to Foo ...
1127 Foo->meta->add_method( 'bar' => sub {...} )
1129 # get a list of all the classes searched
1130 # the method dispatcher in the correct order
1131 Foo->meta->class_precedence_list()
1133 # remove a method from Foo
1134 Foo->meta->remove_method('bar');
1136 # or use this to actually create classes ...
1138 Class::MOP::Class->create(
1141 superclasses => ['Foo'],
1143 Class::MOP:: : Attribute->new('$bar'),
1144 Class::MOP:: : Attribute->new('$baz'),
1147 calculate_bar => sub {...},
1148 construct_baz => sub {...}
1155 This is the largest and most complex part of the Class::MOP
1156 meta-object protocol. It controls the introspection and manipulation
1157 of Perl 5 classes, and it can create them as wlel. The best way to
1158 understand what this module can do, is to read the documentation for
1159 each of its methods.
1163 C<Class::MOP::Class> is a subclass of L<Class::MOP::Module>.
1167 =head2 Class construction
1169 These methods all create new C<Class::MOP::Class> objects. These
1170 objects can represent existing classes, or they can be used to create
1171 new classes from scratch.
1173 The metaclass object for a given class is a singleton. If you attempt
1174 to create a metaclass for the same class twice, you will just get the
1179 =item B<< Class::MOP::Class->create($package_name, %options) >>
1181 This method creates a new C<Class::MOP::Class> object with the given
1182 package name. It accepts a number of options.
1188 An optional version number for the newly created package.
1192 An optional authority for the newly created package.
1194 =item * superclasses
1196 An optional array reference of superclass names.
1200 An optional hash reference of methods for the class. The keys of the
1201 hash reference are method names, and values are subroutine references.
1205 An optional array reference of attributes.
1207 An attribute can be passed as an existing L<Class::MOP::Attribute>
1208 object, I<or> or as a hash reference of options which will be passed
1209 to the attribute metaclass's constructor.
1213 =item B<< Class::MOP::Class->create_anon_class(%options) >>
1215 This method works just like C<< Class::MOP::Class->create >> but it
1216 creates an "anonymous" class. In fact, the class does have a name, but
1217 that name is a unique name generated internally by this module.
1219 It accepts the same C<superclasses>, C<methods>, and C<attributes>
1220 parameters that C<create> accepts.
1222 Anonymous classes are destroyed once the metaclass they are attached
1223 to goes out of scope, and will be removed from Perl's internal symbol
1226 All instances of an anonymous class keep a special reference to the
1227 metaclass object, which prevents the metaclass from going out of scope
1228 while any instances exist.
1230 This only works if the instance if based on a hash reference, however.
1232 =item B<< Class::MOP::Class->initialize($package_name, %options) >>
1234 This method will initialize a C<Class::MOP::Class> object for the
1235 named package. Unlike C<create>, this method I<will not> create a new
1238 The purpose of this method is to retrieve a C<Class::MOP::Class>
1239 object for introspecting an existing class.
1241 If an existing C<Class::MOP::Class> object exists for the named
1242 package, it will be returned, and any options provided will be
1245 If the object does not yet exist, it will be created.
1247 The valid options that can be passed to this method are
1248 C<attribute_metaclass>, C<method_metaclass>,
1249 C<wrapped_method_metaclass>, and C<instance_metaclass>. These are all
1250 optional, and default to the appropriate class in the C<Class::MOP>
1255 =head2 Object instance construction and cloning
1257 These methods are all related to creating and/or cloning object
1262 =item B<< $metaclass->clone_object($instance, %params) >>
1264 This method clones an existing object instance. Any parameters you
1265 provide are will override existing attribute values in the object.
1267 This is a convience method for cloning an object instance, then
1268 blessing it into the appropriate package.
1270 You could implement a clone method in your class, using this method:
1273 my ($self, %params) = @_;
1274 $self->meta->clone_object($self, %params);
1277 =item B<< $metaclass->rebless_instance($instance, %params) >>
1279 This method changes the class of C<$instance> to the metaclass's class.
1281 You can only rebless an instance into a subclass of its current
1282 class. If you pass any additional parameters, these will be treated
1283 like constructor parameters and used to initialize the object's
1284 attributes. Any existing attributes that are already set will be
1287 =item B<< $metaclass->new_object(%params) >>
1289 This method is used to create a new object of the metaclass's
1290 class. Any parameters you provide are used to initialize the
1291 instance's attributes.
1293 =item B<< $metaclass->instance_metaclass >>
1295 Returns the class name of the instance metaclass, see
1296 L<Class::MOP::Instance> for more information on the instance
1299 =item B<< $metaclass->get_meta_instance >>
1301 Returns an instance of the C<instance_metaclass> to be used in the
1302 construction of a new instance of the class.
1306 =head2 Informational predicates
1308 These are a few predicate methods for asking information about the
1313 =item B<< $metaclass->is_anon_class >>
1315 This returns true if the class was created by calling C<<
1316 Class::MOP::Class->create_anon_class >>.
1318 =item B<< $metaclass->is_mutable >>
1320 This returns true if the class is still mutable.
1322 =item B<< $metaclass->is_immutable >>
1324 This returns true if the class has been made immutable.
1326 =item B<< $metaclass->is_pristine >>
1328 A class is I<not> pristine if it has non-inherited attributes or if it
1329 has any generated methods.
1333 =head2 Inheritance Relationships
1337 =item B<< $metaclass->superclasses(@superclasses) >>
1339 This is a read-write accessor which represents the superclass
1340 relationships of the metaclass's class.
1342 This is basically sugar around getting and setting C<@ISA>.
1344 =item B<< $metaclass->class_precedence_list >>
1346 This returns a list of all of the class's ancestor classes. The
1347 classes are returned in method dispatch order.
1349 =item B<< $metaclass->linearized_isa >>
1351 This returns a list based on C<class_precedence_list> but with all
1354 =item B<< $metaclass->subclasses >>
1356 This returns a list of subclasses for this class.
1360 =head2 Method introspection and creation
1362 These methods allow you to introspect a class's methods, as well as
1363 add, remove, or change methods.
1365 Determining what is truly a method in a Perl 5 class requires some
1366 heuristics (aka guessing).
1368 Methods defined outside the package with a fully qualified name (C<sub
1369 Package::name { ... }>) will be included. Similarly, methods named
1370 with a fully qualified name using L<Sub::Name> are also included.
1372 However, we attempt to ignore imported functions.
1374 Ultimately, we are using heuristics to determine what truly is a
1375 method in a class, and these heuristics may get the wrong answer in
1376 some edge cases. However, for most "normal" cases the heuristics work
1381 =item B<< $metaclass->get_method($method_name) >>
1383 This will return a L<Class::MOP::Method> for the specified
1384 C<$method_name>. If the class does not have the specified method, it
1387 =item B<< $metaclass->has_method($method_name) >>
1389 Returns a boolean indicating whether or not the class defines the
1390 named method. It does not include methods inherited from parent
1393 =item B<< $metaclass->get_method_map >>
1395 Returns a hash reference representing the methods defined in this
1396 class. The keys are method names and the values are
1397 L<Class::MOP::Method> objects.
1399 =item B<< $metaclass->get_method_list >>
1401 This will return a list of method I<names> for all methods defined in
1404 =item B<< $metaclass->get_all_methods >>
1406 This will traverse the inheritance hierarchy and return a list of all
1407 the L<Class::MOP::Method> objects for this class and its parents.
1409 =item B<< $metaclass->find_method_by_name($method_name) >>
1411 This will return a L<Class::MOP::Method> for the specified
1412 C<$method_name>. If the class does not have the specified method, it
1415 Unlike C<get_method>, this method I<will> look for the named method in
1418 =item B<< $metaclass->get_all_method_names >>
1420 This will return a list of method I<names> for all of this class's
1421 methods, including inherited methods.
1423 =item B<< $metaclass->find_all_methods_by_name($method_name) >>
1425 This method looks for the named method in the class and all of its
1426 parents. It returns every matching method it finds in the inheritance
1427 tree, so it returns a list of methods.
1429 Each method is returned as a hash reference with three keys. The keys
1430 are C<name>, C<class>, and C<code>. The C<code> key has a
1431 L<Class::MOP::Method> object as its value.
1433 The list of methods is distinct.
1435 =item B<< $metaclass->find_next_method_by_name($method_name) >>
1437 This method returns the first method in any superclass matching the
1438 given name. It is effectively the method that C<SUPER::$method_name>
1441 =item B<< $metaclass->add_method($method_name, $method) >>
1443 This method takes a method name and a subroutine reference, and adds
1444 the method to the class.
1446 The subroutine reference can be a L<Class::MOP::Method>, and you are
1447 strongly encouraged to pass a meta method object instead of a code
1448 reference. If you do so, that object gets stored as part of the
1449 class's method map directly. If not, the meta information will have to
1450 be recreated later, and may be incorrect.
1452 If you provide a method object, this method will clone that object if
1453 the object's package name does not match the class name. This lets us
1454 track the original source of any methods added from other classes
1455 (notably Moose roles).
1457 =item B<< $metaclass->remove_method($method_name) >>
1459 Remove the named method from the class. This method returns the
1460 L<Class::MOP::Method> object for the method.
1464 =head2 Attribute introspection and creation
1466 Because Perl 5 does not have a core concept of attributes in classes,
1467 we can only return information about attributes which have been added
1468 via this class's methods. We cannot discover information about
1469 attributes which are defined in terms of "regular" Perl 5 methods.
1473 =item B<< $metaclass->get_attribute($attribute_name) >>
1475 This will return a L<Class::MOP::Attribute> for the specified
1476 C<$attribute_name>. If the class does not have the specified
1477 attribute, it returns C<undef>
1479 =item B<< $metaclass->has_attribute($attribute_name) >>
1481 Returns a boolean indicating whether or not the class defines the
1482 named attribute. It does not include attributes inherited from parent
1485 =item B<< $metaclass->get_attribute_map >>
1487 Returns a hash reference representing the attributes defined in this
1488 class. The keys are attribute names and the values are
1489 L<Class::MOP::Attribute> objects.
1491 =item B<< $metaclass->get_attribute_list >>
1493 This will return a list of attributes I<names> for all attributes
1494 defined in this class.
1496 =item B<< $metaclass->get_all_attributes >>
1498 This will traverse the inheritance hierarchy and return a list of all
1499 the L<Class::MOP::Attribute> objects for this class and its parents.
1501 This method can also be called as C<compute_all_applicable_attributes>.
1503 =item B<< $metaclass->find_attribute_by_name($attribute_name) >>
1505 This will return a L<Class::MOP::Attribute> for the specified
1506 C<$attribute_name>. If the class does not have the specified
1507 attribute, it returns C<undef>
1509 Unlike C<get_attribute>, this attribute I<will> look for the named
1510 attribute in superclasses.
1512 =item B<< $metaclass->add_attribute(...) >>
1514 This method accepts either an existing L<Class::MOP::Attribute>
1515 object, or parameters suitable for passing to that class's C<new>
1518 The attribute provided will be added to the class.
1520 Any accessor methods defined by the attribute will be added to the
1521 class when the attribute is added.
1523 If an attribute of the same name already exists, the old attribute
1524 will be removed first.
1526 =item B<< $metaclass->remove_attribute($attribute_name) >>
1528 This will remove the named attribute from the class, and
1529 L<Class::MOP::Attribute> object.
1531 Removing an attribute also removes any accessor methods defined by the
1534 However, note that removing an attribute will only affect I<future>
1535 object instances created for this class, not existing instances.
1537 =item B<< $metaclass->attribute_metaclass >>
1539 Returns the class name of the attribute metaclass for this class. By
1540 default, this is L<Class::MOP::Attribute>. for more information on
1544 =head2 Class Immutability
1546 Making a class immutable "freezes" the class definition. You can no
1547 longer call methods which alter the class, such as adding or removing
1548 methods or attributes.
1550 Making a class immutable lets us optimize the class by inlning some
1551 methods, and also allows us to optimize some methods on the metaclass
1554 The immutabilization system in L<Moose> takes much greater advantage
1555 of the inlining features than Class::MOP itself does.
1559 =item B<< $metaclass->make_immutable(%options) >>
1561 This method will create an immutable transformer and uses it to make
1562 the class and its metaclass object immutable.
1564 Details of how immutabilization works are in L<Class::MOP::Immutable>
1567 =item B<< $metaclass->make_mutable >>
1569 Calling this method reverse the immutabilization transformation.
1571 =item B<< $metaclass->get_immutable_transformer >>
1573 If the class has been made immutable previously, this returns the
1574 L<Class::MOP::Immutable> object that was created to do the
1577 If the class was never made immutable, this method will die.
1581 =head2 Method Modifiers
1583 Method modifiers are hooks which allow a method to be wrapped with
1584 I<before>, I<after> and I<around> method modifiers. Every time a
1585 method is called, it's modifiers are also called.
1587 A class can modify its own methods, as well as methods defined in
1590 =head3 How method modifiers work?
1592 Method modifiers work by wrapping the original method and then
1593 replacing it in the class's symbol table. The wrappers will handle
1594 calling all the modifiers in the appropariate orders and preserving
1595 the calling context for the original method.
1597 The return values of C<before> and C<after> modifiers are
1598 ignored. This is because their purpose is B<not> to filter the input
1599 and output of the primary method (this is done with an I<around>
1602 This may seem like an odd restriction to some, but doing this allows
1603 for simple code to be added at the beginning or end of a method call
1604 without altering the function of the wrapped method or placing any
1605 extra responsibility on the code of the modifier.
1607 Of course if you have more complex needs, you can use the C<around>
1608 modifier which allows you to change both the parameters passed to the
1609 wrapped method, as well as its return value.
1611 Before and around modifiers are called in last-defined-first-called
1612 order, while after modifiers are called in first-defined-first-called
1613 order. So the call tree might looks something like this:
1625 =head3 What is the performance impact?
1627 Of course there is a performance cost associated with method
1628 modifiers, but we have made every effort to make that cost directly
1629 proportional to the number of modifier features you utilize.
1631 The wrapping method does it's best to B<only> do as much work as it
1632 absolutely needs to. In order to do this we have moved some of the
1633 performance costs to set-up time, where they are easier to amortize.
1635 All this said, our benchmarks have indicated the following:
1637 simple wrapper with no modifiers 100% slower
1638 simple wrapper with simple before modifier 400% slower
1639 simple wrapper with simple after modifier 450% slower
1640 simple wrapper with simple around modifier 500-550% slower
1641 simple wrapper with all 3 modifiers 1100% slower
1643 These numbers may seem daunting, but you must remember, every feature
1644 comes with some cost. To put things in perspective, just doing a
1645 simple C<AUTOLOAD> which does nothing but extract the name of the
1646 method called and return it costs about 400% over a normal method
1651 =item B<< $metaclass->add_before_method_modifier($method_name, $code) >>
1653 This wraps the specified method with the supplied subroutine
1654 reference. The modifier will be called as a method itself, and will
1655 receive the same arguments as are passed to the method.
1657 When the modifier exits, the wrapped method will be called.
1659 The return value of the modifier will be ignored.
1661 =item B<< $metaclass->add_after_method_modifier($method_name, $code) >>
1663 This wraps the specified method with the supplied subroutine
1664 reference. The modifier will be called as a method itself, and will
1665 receive the same arguments as are passed to the method.
1667 When the wrapped methods exits, the modifier will be called.
1669 The return value of the modifier will be ignored.
1671 =item B<< $metaclass->add_around_method_modifier($method_name, $code) >>
1673 This wraps the specified method with the supplied subroutine
1676 The first argument passed to the modifier will be a subroutine
1677 reference to the wrapped method. The second argument is the object,
1678 and after that come any arguments passed when the method is called.
1680 The around modifier can choose to call the original method, as well as
1681 what arguments to pass if it does so.
1683 The return value of the modifier is what will be seen by the caller.
1689 Stevan Little E<lt>stevan@iinteractive.comE<gt>
1691 =head1 COPYRIGHT AND LICENSE
1693 Copyright 2006-2009 by Infinity Interactive, Inc.
1695 L<http://www.iinteractive.com>
1697 This library is free software; you can redistribute it and/or modify
1698 it under the same terms as Perl itself.