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 = '0.79';
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 "Class::MOP::class_of(" . $self->name . ") => ("
173 . (ref($self)) . ")" . " is not compatible with the " .
174 "Class::MOP::class_of(".$superclass_name . ") => ("
175 . ($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 = $self->initialize(blessed($instance));
418 $old_metaclass->rebless_instance_away($instance, $self, %params);
420 my $meta_instance = $self->get_meta_instance();
422 $self->name->isa($old_metaclass->name)
423 || confess "You may rebless only into a subclass of (". $old_metaclass->name ."), of which (". $self->name .") isn't.";
426 # we use $_[1] here because of t/306_rebless_overload.t regressions on 5.8.8
427 $meta_instance->rebless_instance_structure($_[1], $self);
429 foreach my $attr ( $self->compute_all_applicable_attributes ) {
430 if ( $attr->has_value($instance) ) {
431 if ( defined( my $init_arg = $attr->init_arg ) ) {
432 $params{$init_arg} = $attr->get_value($instance)
433 unless exists $params{$init_arg};
436 $attr->set_value($instance, $attr->get_value($instance));
441 foreach my $attr ($self->compute_all_applicable_attributes) {
442 $attr->initialize_instance_slot($meta_instance, $instance, \%params);
448 sub rebless_instance_away {
449 # this intentionally does nothing, it is just a hook
456 my $var_spec = { sigil => '@', type => 'ARRAY', name => 'ISA' };
459 @{$self->get_package_symbol($var_spec)} = @supers;
462 # on 5.8 and below, we need to call
463 # a method to get Perl to detect
464 # a cycle in the class hierarchy
465 my $class = $self->name;
469 # we need to check the metaclass
470 # compatibility here so that we can
471 # be sure that the superclass is
472 # not potentially creating an issues
473 # we don't know about
475 $self->check_metaclass_compatibility();
476 $self->update_meta_instance_dependencies();
478 @{$self->get_package_symbol($var_spec)};
484 my $super_class = $self->name;
486 if ( Class::MOP::HAVE_ISAREV() ) {
487 return @{ $super_class->mro::get_isarev() };
491 my $find_derived_classes;
492 $find_derived_classes = sub {
493 my ($outer_class) = @_;
495 my $symbol_table_hashref = do { no strict 'refs'; \%{"${outer_class}::"} };
498 for my $symbol ( keys %$symbol_table_hashref ) {
499 next SYMBOL if $symbol !~ /\A (\w+):: \z/x;
500 my $inner_class = $1;
502 next SYMBOL if $inner_class eq 'SUPER'; # skip '*::SUPER'
506 ? "${outer_class}::$inner_class"
509 if ( $class->isa($super_class) and $class ne $super_class ) {
510 push @derived_classes, $class;
513 next SYMBOL if $class eq 'main'; # skip 'main::*'
515 $find_derived_classes->($class);
519 my $root_class = q{};
520 $find_derived_classes->($root_class);
522 undef $find_derived_classes;
524 @derived_classes = sort { $a->isa($b) ? 1 : $b->isa($a) ? -1 : 0 } @derived_classes;
526 return @derived_classes;
532 return @{ mro::get_linear_isa( (shift)->name ) };
535 sub class_precedence_list {
537 my $name = $self->name;
539 unless (Class::MOP::IS_RUNNING_ON_5_10()) {
541 # We need to check for circular inheritance here
542 # if we are are not on 5.10, cause 5.8 detects it
543 # late. This will do nothing if all is well, and
544 # blow up otherwise. Yes, it's an ugly hack, better
545 # suggestions are welcome.
547 ($name || return)->isa('This is a test for circular inheritance')
550 # if our mro is c3, we can
551 # just grab the linear_isa
552 if (mro::get_mro($name) eq 'c3') {
553 return @{ mro::get_linear_isa($name) }
557 # we can't grab the linear_isa for dfs
558 # since it has all the duplicates
563 $self->initialize($_)->class_precedence_list()
564 } $self->superclasses()
571 sub wrap_method_body {
572 my ( $self, %args ) = @_;
574 ('CODE' eq ref $args{body})
575 || confess "Your code block must be a CODE reference";
577 $self->method_metaclass->wrap(
578 package_name => $self->name,
584 my ($self, $method_name, $method) = @_;
585 (defined $method_name && $method_name)
586 || confess "You must define a method name";
589 if (blessed($method)) {
590 $body = $method->body;
591 if ($method->package_name ne $self->name) {
592 $method = $method->clone(
593 package_name => $self->name,
595 ) if $method->can('clone');
600 $method = $self->wrap_method_body( body => $body, name => $method_name );
603 $method->attach_to_class($self);
605 # This used to call get_method_map, which meant we would build all
606 # the method objects for the class just because we added one
607 # method. This is hackier, but quicker too.
608 $self->{methods}{$method_name} = $method;
610 my $full_method_name = ($self->name . '::' . $method_name);
611 $self->add_package_symbol(
612 { sigil => '&', type => 'CODE', name => $method_name },
613 Class::MOP::subname($full_method_name => $body)
618 my $fetch_and_prepare_method = sub {
619 my ($self, $method_name) = @_;
620 my $wrapped_metaclass = $self->wrapped_method_metaclass;
622 my $method = $self->get_method($method_name);
623 # if we dont have local ...
625 # try to find the next method
626 $method = $self->find_next_method_by_name($method_name);
627 # die if it does not exist
629 || confess "The method '$method_name' was not found in the inheritance hierarchy for " . $self->name;
630 # and now make sure to wrap it
631 # even if it is already wrapped
632 # because we need a new sub ref
633 $method = $wrapped_metaclass->wrap($method);
636 # now make sure we wrap it properly
637 $method = $wrapped_metaclass->wrap($method)
638 unless $method->isa($wrapped_metaclass);
640 $self->add_method($method_name => $method);
644 sub add_before_method_modifier {
645 my ($self, $method_name, $method_modifier) = @_;
646 (defined $method_name && $method_name)
647 || confess "You must pass in a method name";
648 my $method = $fetch_and_prepare_method->($self, $method_name);
649 $method->add_before_modifier(
650 Class::MOP::subname(':before' => $method_modifier)
654 sub add_after_method_modifier {
655 my ($self, $method_name, $method_modifier) = @_;
656 (defined $method_name && $method_name)
657 || confess "You must pass in a method name";
658 my $method = $fetch_and_prepare_method->($self, $method_name);
659 $method->add_after_modifier(
660 Class::MOP::subname(':after' => $method_modifier)
664 sub add_around_method_modifier {
665 my ($self, $method_name, $method_modifier) = @_;
666 (defined $method_name && $method_name)
667 || confess "You must pass in a method name";
668 my $method = $fetch_and_prepare_method->($self, $method_name);
669 $method->add_around_modifier(
670 Class::MOP::subname(':around' => $method_modifier)
675 # the methods above used to be named like this:
676 # ${pkg}::${method}:(before|after|around)
677 # but this proved problematic when using one modifier
678 # to wrap multiple methods (something which is likely
679 # to happen pretty regularly IMO). So instead of naming
680 # it like this, I have chosen to just name them purely
681 # with their modifier names, like so:
682 # :(before|after|around)
683 # The fact is that in a stack trace, it will be fairly
684 # evident from the context what method they are attached
685 # to, and so don't need the fully qualified name.
691 $self->add_method(@_);
695 my ($self, $method_name) = @_;
696 (defined $method_name && $method_name)
697 || confess "You must define a method name";
699 exists $self->{methods}{$method_name} || exists $self->get_method_map->{$method_name};
703 my ($self, $method_name) = @_;
704 (defined $method_name && $method_name)
705 || confess "You must define a method name";
707 return $self->{methods}{$method_name} || $self->get_method_map->{$method_name};
711 my ($self, $method_name) = @_;
712 (defined $method_name && $method_name)
713 || confess "You must define a method name";
715 my $removed_method = delete $self->get_method_map->{$method_name};
717 $self->remove_package_symbol(
718 { sigil => '&', type => 'CODE', name => $method_name }
721 $removed_method->detach_from_class if $removed_method;
723 $self->update_package_cache_flag; # still valid, since we just removed the method from the map
725 return $removed_method;
728 sub get_method_list {
730 keys %{$self->get_method_map};
733 sub find_method_by_name {
734 my ($self, $method_name) = @_;
735 (defined $method_name && $method_name)
736 || confess "You must define a method name to find";
737 foreach my $class ($self->linearized_isa) {
738 # fetch the meta-class ...
739 my $meta = $self->initialize($class);
740 return $meta->get_method($method_name)
741 if $meta->has_method($method_name);
746 sub get_all_methods {
748 my %methods = map { %{ $self->initialize($_)->get_method_map } } reverse $self->linearized_isa;
749 return values %methods;
753 sub compute_all_applicable_methods {
757 class => $_->package_name,
758 code => $_, # sigh, overloading
760 } shift->get_all_methods(@_);
763 sub get_all_method_names {
766 grep { $uniq{$_}++ == 0 } map { $_->name } $self->get_all_methods;
769 sub find_all_methods_by_name {
770 my ($self, $method_name) = @_;
771 (defined $method_name && $method_name)
772 || confess "You must define a method name to find";
774 foreach my $class ($self->linearized_isa) {
775 # fetch the meta-class ...
776 my $meta = $self->initialize($class);
778 name => $method_name,
780 code => $meta->get_method($method_name)
781 } if $meta->has_method($method_name);
786 sub find_next_method_by_name {
787 my ($self, $method_name) = @_;
788 (defined $method_name && $method_name)
789 || confess "You must define a method name to find";
790 my @cpl = $self->linearized_isa;
791 shift @cpl; # discard ourselves
792 foreach my $class (@cpl) {
793 # fetch the meta-class ...
794 my $meta = $self->initialize($class);
795 return $meta->get_method($method_name)
796 if $meta->has_method($method_name);
805 # either we have an attribute object already
806 # or we need to create one from the args provided
807 my $attribute = blessed($_[0]) ? $_[0] : $self->attribute_metaclass->new(@_);
808 # make sure it is derived from the correct type though
809 ($attribute->isa('Class::MOP::Attribute'))
810 || confess "Your attribute must be an instance of Class::MOP::Attribute (or a subclass)";
812 # first we attach our new attribute
813 # because it might need certain information
814 # about the class which it is attached to
815 $attribute->attach_to_class($self);
817 # then we remove attributes of a conflicting
818 # name here so that we can properly detach
819 # the old attr object, and remove any
820 # accessors it would have generated
821 if ( $self->has_attribute($attribute->name) ) {
822 $self->remove_attribute($attribute->name);
824 $self->invalidate_meta_instances();
827 # then onto installing the new accessors
828 $self->get_attribute_map->{$attribute->name} = $attribute;
830 # invalidate package flag here
831 my $e = do { local $@; eval { $attribute->install_accessors() }; $@ };
833 $self->remove_attribute($attribute->name);
840 sub update_meta_instance_dependencies {
843 if ( $self->{meta_instance_dependencies} ) {
844 return $self->add_meta_instance_dependencies;
848 sub add_meta_instance_dependencies {
851 $self->remove_meta_instance_dependencies;
853 my @attrs = $self->compute_all_applicable_attributes();
856 my @classes = grep { not $seen{$_->name}++ } map { $_->associated_class } @attrs;
858 foreach my $class ( @classes ) {
859 $class->add_dependent_meta_instance($self);
862 $self->{meta_instance_dependencies} = \@classes;
865 sub remove_meta_instance_dependencies {
868 if ( my $classes = delete $self->{meta_instance_dependencies} ) {
869 foreach my $class ( @$classes ) {
870 $class->remove_dependent_meta_instance($self);
880 sub add_dependent_meta_instance {
881 my ( $self, $metaclass ) = @_;
882 push @{ $self->{dependent_meta_instances} }, $metaclass;
885 sub remove_dependent_meta_instance {
886 my ( $self, $metaclass ) = @_;
887 my $name = $metaclass->name;
888 @$_ = grep { $_->name ne $name } @$_ for $self->{dependent_meta_instances};
891 sub invalidate_meta_instances {
893 $_->invalidate_meta_instance() for $self, @{ $self->{dependent_meta_instances} };
896 sub invalidate_meta_instance {
898 undef $self->{_meta_instance};
902 my ($self, $attribute_name) = @_;
903 (defined $attribute_name && $attribute_name)
904 || confess "You must define an attribute name";
905 exists $self->get_attribute_map->{$attribute_name};
909 my ($self, $attribute_name) = @_;
910 (defined $attribute_name && $attribute_name)
911 || confess "You must define an attribute name";
912 return $self->get_attribute_map->{$attribute_name}
914 # this will return undef anyway, so no need ...
915 # if $self->has_attribute($attribute_name);
919 sub remove_attribute {
920 my ($self, $attribute_name) = @_;
921 (defined $attribute_name && $attribute_name)
922 || confess "You must define an attribute name";
923 my $removed_attribute = $self->get_attribute_map->{$attribute_name};
924 return unless defined $removed_attribute;
925 delete $self->get_attribute_map->{$attribute_name};
926 $self->invalidate_meta_instances();
927 $removed_attribute->remove_accessors();
928 $removed_attribute->detach_from_class();
929 return $removed_attribute;
932 sub get_attribute_list {
934 keys %{$self->get_attribute_map};
937 sub get_all_attributes {
938 shift->compute_all_applicable_attributes(@_);
941 sub compute_all_applicable_attributes {
943 my %attrs = map { %{ $self->initialize($_)->get_attribute_map } } reverse $self->linearized_isa;
944 return values %attrs;
947 sub find_attribute_by_name {
948 my ($self, $attr_name) = @_;
949 foreach my $class ($self->linearized_isa) {
950 # fetch the meta-class ...
951 my $meta = $self->initialize($class);
952 return $meta->get_attribute($attr_name)
953 if $meta->has_attribute($attr_name);
958 # check if we can reinitialize
962 # if any local attr is defined
963 return if $self->get_attribute_list;
965 # or any non-declared methods
966 if ( my @methods = values %{ $self->get_method_map } ) {
967 my $metaclass = $self->method_metaclass;
968 foreach my $method ( @methods ) {
969 return if $method->isa("Class::MOP::Method::Generated");
970 # FIXME do we need to enforce this too? return unless $method->isa($metaclass);
980 sub is_immutable { 0 }
982 sub immutable_transformer { $_[0]->{immutable_transformer} }
983 sub _set_immutable_transformer { $_[0]->{immutable_transformer} = $_[1] }
988 return if $self->is_immutable;
990 my $transformer = $self->immutable_transformer
991 || $self->_make_immutable_transformer(@_);
993 $self->_set_immutable_transformer($transformer);
995 $transformer->make_metaclass_immutable;
999 my %Default_Immutable_Options = (
1000 read_only => [qw/superclasses/],
1008 remove_package_symbol
1012 class_precedence_list => 'ARRAY',
1013 # FIXME perl 5.10 memoizes this on its own, no need?
1014 linearized_isa => 'ARRAY',
1015 get_all_methods => 'ARRAY',
1016 get_all_method_names => 'ARRAY',
1017 compute_all_applicable_attributes => 'ARRAY',
1018 get_meta_instance => 'SCALAR',
1019 get_method_map => 'SCALAR',
1023 # this is ugly, but so are typeglobs,
1024 # so whattayahgonnadoboutit
1027 add_package_symbol => sub {
1028 my $original = shift;
1029 confess "Cannot add package symbols to an immutable metaclass"
1030 unless ( caller(2) )[3] eq
1031 'Class::MOP::Package::get_package_symbol';
1033 # This is a workaround for a bug in 5.8.1 which thinks that
1034 # goto $original->body
1035 # is trying to go to a label
1036 my $body = $original->body;
1042 sub _default_immutable_transformer_options {
1043 return %Default_Immutable_Options;
1047 sub _make_immutable_transformer {
1050 Class::MOP::Immutable->new(
1052 $self->_default_immutable_transformer_options,
1060 return if $self->is_mutable;
1062 $self->immutable_transformer->make_metaclass_mutable;
1073 Class::MOP::Class - Class Meta Object
1077 # assuming that class Foo
1078 # has been defined, you can
1080 # use this for introspection ...
1082 # add a method to Foo ...
1083 Foo->meta->add_method( 'bar' => sub {...} )
1085 # get a list of all the classes searched
1086 # the method dispatcher in the correct order
1087 Foo->meta->class_precedence_list()
1089 # remove a method from Foo
1090 Foo->meta->remove_method('bar');
1092 # or use this to actually create classes ...
1094 Class::MOP::Class->create(
1097 superclasses => ['Foo'],
1099 Class::MOP:: : Attribute->new('$bar'),
1100 Class::MOP:: : Attribute->new('$baz'),
1103 calculate_bar => sub {...},
1104 construct_baz => sub {...}
1111 The Class Protocol is the largest and most complex part of the
1112 Class::MOP meta-object protocol. It controls the introspection and
1113 manipulation of Perl 5 classes, and it can create them as well. The
1114 best way to understand what this module can do, is to read the
1115 documentation for each of its methods.
1119 C<Class::MOP::Class> is a subclass of L<Class::MOP::Module>.
1123 =head2 Class construction
1125 These methods all create new C<Class::MOP::Class> objects. These
1126 objects can represent existing classes, or they can be used to create
1127 new classes from scratch.
1129 The metaclass object for a given class is a singleton. If you attempt
1130 to create a metaclass for the same class twice, you will just get the
1135 =item B<< Class::MOP::Class->create($package_name, %options) >>
1137 This method creates a new C<Class::MOP::Class> object with the given
1138 package name. It accepts a number of options.
1144 An optional version number for the newly created package.
1148 An optional authority for the newly created package.
1150 =item * superclasses
1152 An optional array reference of superclass names.
1156 An optional hash reference of methods for the class. The keys of the
1157 hash reference are method names, and values are subroutine references.
1161 An optional array reference of attributes.
1163 An attribute can be passed as an existing L<Class::MOP::Attribute>
1164 object, I<or> or as a hash reference of options which will be passed
1165 to the attribute metaclass's constructor.
1169 =item B<< Class::MOP::Class->create_anon_class(%options) >>
1171 This method works just like C<< Class::MOP::Class->create >> but it
1172 creates an "anonymous" class. In fact, the class does have a name, but
1173 that name is a unique name generated internally by this module.
1175 It accepts the same C<superclasses>, C<methods>, and C<attributes>
1176 parameters that C<create> accepts.
1178 Anonymous classes are destroyed once the metaclass they are attached
1179 to goes out of scope, and will be removed from Perl's internal symbol
1182 All instances of an anonymous class keep a special reference to the
1183 metaclass object, which prevents the metaclass from going out of scope
1184 while any instances exist.
1186 This only works if the instance if based on a hash reference, however.
1188 =item B<< Class::MOP::Class->initialize($package_name, %options) >>
1190 This method will initialize a C<Class::MOP::Class> object for the
1191 named package. Unlike C<create>, this method I<will not> create a new
1194 The purpose of this method is to retrieve a C<Class::MOP::Class>
1195 object for introspecting an existing class.
1197 If an existing C<Class::MOP::Class> object exists for the named
1198 package, it will be returned, and any options provided will be
1201 If the object does not yet exist, it will be created.
1203 The valid options that can be passed to this method are
1204 C<attribute_metaclass>, C<method_metaclass>,
1205 C<wrapped_method_metaclass>, and C<instance_metaclass>. These are all
1206 optional, and default to the appropriate class in the C<Class::MOP>
1211 =head2 Object instance construction and cloning
1213 These methods are all related to creating and/or cloning object
1218 =item B<< $metaclass->clone_object($instance, %params) >>
1220 This method clones an existing object instance. Any parameters you
1221 provide are will override existing attribute values in the object.
1223 This is a convenience method for cloning an object instance, then
1224 blessing it into the appropriate package.
1226 You could implement a clone method in your class, using this method:
1229 my ($self, %params) = @_;
1230 $self->meta->clone_object($self, %params);
1233 =item B<< $metaclass->rebless_instance($instance, %params) >>
1235 This method changes the class of C<$instance> to the metaclass's class.
1237 You can only rebless an instance into a subclass of its current
1238 class. If you pass any additional parameters, these will be treated
1239 like constructor parameters and used to initialize the object's
1240 attributes. Any existing attributes that are already set will be
1243 Before reblessing the instance, this method will call
1244 C<rebless_instance_away> on the instance's current metaclass. This method
1245 will be passed the instance, the new metaclass, and any parameters
1246 specified to C<rebless_instance>. By default, C<rebless_instance_away>
1247 does nothing; it is merely a hook.
1249 =item B<< $metaclass->new_object(%params) >>
1251 This method is used to create a new object of the metaclass's
1252 class. Any parameters you provide are used to initialize the
1253 instance's attributes.
1255 =item B<< $metaclass->instance_metaclass >>
1257 Returns the class name of the instance metaclass, see
1258 L<Class::MOP::Instance> for more information on the instance
1261 =item B<< $metaclass->get_meta_instance >>
1263 Returns an instance of the C<instance_metaclass> to be used in the
1264 construction of a new instance of the class.
1268 =head2 Informational predicates
1270 These are a few predicate methods for asking information about the
1275 =item B<< $metaclass->is_anon_class >>
1277 This returns true if the class was created by calling C<<
1278 Class::MOP::Class->create_anon_class >>.
1280 =item B<< $metaclass->is_mutable >>
1282 This returns true if the class is still mutable.
1284 =item B<< $metaclass->is_immutable >>
1286 This returns true if the class has been made immutable.
1288 =item B<< $metaclass->is_pristine >>
1290 A class is I<not> pristine if it has non-inherited attributes or if it
1291 has any generated methods.
1295 =head2 Inheritance Relationships
1299 =item B<< $metaclass->superclasses(@superclasses) >>
1301 This is a read-write accessor which represents the superclass
1302 relationships of the metaclass's class.
1304 This is basically sugar around getting and setting C<@ISA>.
1306 =item B<< $metaclass->class_precedence_list >>
1308 This returns a list of all of the class's ancestor classes. The
1309 classes are returned in method dispatch order.
1311 =item B<< $metaclass->linearized_isa >>
1313 This returns a list based on C<class_precedence_list> but with all
1316 =item B<< $metaclass->subclasses >>
1318 This returns a list of subclasses for this class.
1322 =head2 Method introspection and creation
1324 These methods allow you to introspect a class's methods, as well as
1325 add, remove, or change methods.
1327 Determining what is truly a method in a Perl 5 class requires some
1328 heuristics (aka guessing).
1330 Methods defined outside the package with a fully qualified name (C<sub
1331 Package::name { ... }>) will be included. Similarly, methods named
1332 with a fully qualified name using L<Sub::Name> are also included.
1334 However, we attempt to ignore imported functions.
1336 Ultimately, we are using heuristics to determine what truly is a
1337 method in a class, and these heuristics may get the wrong answer in
1338 some edge cases. However, for most "normal" cases the heuristics work
1343 =item B<< $metaclass->get_method($method_name) >>
1345 This will return a L<Class::MOP::Method> for the specified
1346 C<$method_name>. If the class does not have the specified method, it
1349 =item B<< $metaclass->has_method($method_name) >>
1351 Returns a boolean indicating whether or not the class defines the
1352 named method. It does not include methods inherited from parent
1355 =item B<< $metaclass->get_method_map >>
1357 Returns a hash reference representing the methods defined in this
1358 class. The keys are method names and the values are
1359 L<Class::MOP::Method> objects.
1361 =item B<< $metaclass->get_method_list >>
1363 This will return a list of method I<names> for all methods defined in
1366 =item B<< $metaclass->get_all_methods >>
1368 This will traverse the inheritance hierarchy and return a list of all
1369 the L<Class::MOP::Method> objects for this class and its parents.
1371 =item B<< $metaclass->find_method_by_name($method_name) >>
1373 This will return a L<Class::MOP::Method> for the specified
1374 C<$method_name>. If the class does not have the specified method, it
1377 Unlike C<get_method>, this method I<will> look for the named method in
1380 =item B<< $metaclass->get_all_method_names >>
1382 This will return a list of method I<names> for all of this class's
1383 methods, including inherited methods.
1385 =item B<< $metaclass->find_all_methods_by_name($method_name) >>
1387 This method looks for the named method in the class and all of its
1388 parents. It returns every matching method it finds in the inheritance
1389 tree, so it returns a list of methods.
1391 Each method is returned as a hash reference with three keys. The keys
1392 are C<name>, C<class>, and C<code>. The C<code> key has a
1393 L<Class::MOP::Method> object as its value.
1395 The list of methods is distinct.
1397 =item B<< $metaclass->find_next_method_by_name($method_name) >>
1399 This method returns the first method in any superclass matching the
1400 given name. It is effectively the method that C<SUPER::$method_name>
1403 =item B<< $metaclass->add_method($method_name, $method) >>
1405 This method takes a method name and a subroutine reference, and adds
1406 the method to the class.
1408 The subroutine reference can be a L<Class::MOP::Method>, and you are
1409 strongly encouraged to pass a meta method object instead of a code
1410 reference. If you do so, that object gets stored as part of the
1411 class's method map directly. If not, the meta information will have to
1412 be recreated later, and may be incorrect.
1414 If you provide a method object, this method will clone that object if
1415 the object's package name does not match the class name. This lets us
1416 track the original source of any methods added from other classes
1417 (notably Moose roles).
1419 =item B<< $metaclass->remove_method($method_name) >>
1421 Remove the named method from the class. This method returns the
1422 L<Class::MOP::Method> object for the method.
1424 =item B<< $metaclass->method_metaclass >>
1426 Returns the class name of the method metaclass, see
1427 L<Class::MOP::Method> for more information on the method metaclass.
1429 =item B<< $metaclass->wrapped_method_metaclass >>
1431 Returns the class name of the wrapped method metaclass, see
1432 L<Class::MOP::Method::Wrapped> for more information on the wrapped
1437 =head2 Attribute introspection and creation
1439 Because Perl 5 does not have a core concept of attributes in classes,
1440 we can only return information about attributes which have been added
1441 via this class's methods. We cannot discover information about
1442 attributes which are defined in terms of "regular" Perl 5 methods.
1446 =item B<< $metaclass->get_attribute($attribute_name) >>
1448 This will return a L<Class::MOP::Attribute> for the specified
1449 C<$attribute_name>. If the class does not have the specified
1450 attribute, it returns C<undef>
1452 =item B<< $metaclass->has_attribute($attribute_name) >>
1454 Returns a boolean indicating whether or not the class defines the
1455 named attribute. It does not include attributes inherited from parent
1458 =item B<< $metaclass->get_attribute_map >>
1460 Returns a hash reference representing the attributes defined in this
1461 class. The keys are attribute names and the values are
1462 L<Class::MOP::Attribute> objects.
1464 =item B<< $metaclass->get_attribute_list >>
1466 This will return a list of attributes I<names> for all attributes
1467 defined in this class.
1469 =item B<< $metaclass->get_all_attributes >>
1471 This will traverse the inheritance hierarchy and return a list of all
1472 the L<Class::MOP::Attribute> objects for this class and its parents.
1474 This method can also be called as C<compute_all_applicable_attributes>.
1476 =item B<< $metaclass->find_attribute_by_name($attribute_name) >>
1478 This will return a L<Class::MOP::Attribute> for the specified
1479 C<$attribute_name>. If the class does not have the specified
1480 attribute, it returns C<undef>
1482 Unlike C<get_attribute>, this attribute I<will> look for the named
1483 attribute in superclasses.
1485 =item B<< $metaclass->add_attribute(...) >>
1487 This method accepts either an existing L<Class::MOP::Attribute>
1488 object, or parameters suitable for passing to that class's C<new>
1491 The attribute provided will be added to the class.
1493 Any accessor methods defined by the attribute will be added to the
1494 class when the attribute is added.
1496 If an attribute of the same name already exists, the old attribute
1497 will be removed first.
1499 =item B<< $metaclass->remove_attribute($attribute_name) >>
1501 This will remove the named attribute from the class, and
1502 L<Class::MOP::Attribute> object.
1504 Removing an attribute also removes any accessor methods defined by the
1507 However, note that removing an attribute will only affect I<future>
1508 object instances created for this class, not existing instances.
1510 =item B<< $metaclass->attribute_metaclass >>
1512 Returns the class name of the attribute metaclass for this class. By
1513 default, this is L<Class::MOP::Attribute>. for more information on
1517 =head2 Class Immutability
1519 Making a class immutable "freezes" the class definition. You can no
1520 longer call methods which alter the class, such as adding or removing
1521 methods or attributes.
1523 Making a class immutable lets us optimize the class by inlining some
1524 methods, and also allows us to optimize some methods on the metaclass
1527 The immutabilization system in L<Moose> takes much greater advantage
1528 of the inlining features than Class::MOP itself does.
1532 =item B<< $metaclass->make_immutable(%options) >>
1534 This method will create an immutable transformer and uses it to make
1535 the class and its metaclass object immutable.
1537 Details of how immutabilization works are in L<Class::MOP::Immutable>
1540 =item B<< $metaclass->make_mutable >>
1542 Calling this method reverse the immutabilization transformation.
1544 =item B<< $metaclass->immutable_transformer >>
1546 If the class has been made immutable previously, this returns the
1547 L<Class::MOP::Immutable> object that was created to do the
1550 If the class was never made immutable, this method will die.
1554 =head2 Method Modifiers
1556 Method modifiers are hooks which allow a method to be wrapped with
1557 I<before>, I<after> and I<around> method modifiers. Every time a
1558 method is called, it's modifiers are also called.
1560 A class can modify its own methods, as well as methods defined in
1563 =head3 How method modifiers work?
1565 Method modifiers work by wrapping the original method and then
1566 replacing it in the class's symbol table. The wrappers will handle
1567 calling all the modifiers in the appropriate order and preserving the
1568 calling context for the original method.
1570 The return values of C<before> and C<after> modifiers are
1571 ignored. This is because their purpose is B<not> to filter the input
1572 and output of the primary method (this is done with an I<around>
1575 This may seem like an odd restriction to some, but doing this allows
1576 for simple code to be added at the beginning or end of a method call
1577 without altering the function of the wrapped method or placing any
1578 extra responsibility on the code of the modifier.
1580 Of course if you have more complex needs, you can use the C<around>
1581 modifier which allows you to change both the parameters passed to the
1582 wrapped method, as well as its return value.
1584 Before and around modifiers are called in last-defined-first-called
1585 order, while after modifiers are called in first-defined-first-called
1586 order. So the call tree might looks something like this:
1598 =head3 What is the performance impact?
1600 Of course there is a performance cost associated with method
1601 modifiers, but we have made every effort to make that cost directly
1602 proportional to the number of modifier features you utilize.
1604 The wrapping method does it's best to B<only> do as much work as it
1605 absolutely needs to. In order to do this we have moved some of the
1606 performance costs to set-up time, where they are easier to amortize.
1608 All this said, our benchmarks have indicated the following:
1610 simple wrapper with no modifiers 100% slower
1611 simple wrapper with simple before modifier 400% slower
1612 simple wrapper with simple after modifier 450% slower
1613 simple wrapper with simple around modifier 500-550% slower
1614 simple wrapper with all 3 modifiers 1100% slower
1616 These numbers may seem daunting, but you must remember, every feature
1617 comes with some cost. To put things in perspective, just doing a
1618 simple C<AUTOLOAD> which does nothing but extract the name of the
1619 method called and return it costs about 400% over a normal method
1624 =item B<< $metaclass->add_before_method_modifier($method_name, $code) >>
1626 This wraps the specified method with the supplied subroutine
1627 reference. The modifier will be called as a method itself, and will
1628 receive the same arguments as are passed to the method.
1630 When the modifier exits, the wrapped method will be called.
1632 The return value of the modifier will be ignored.
1634 =item B<< $metaclass->add_after_method_modifier($method_name, $code) >>
1636 This wraps the specified method with the supplied subroutine
1637 reference. The modifier will be called as a method itself, and will
1638 receive the same arguments as are passed to the method.
1640 When the wrapped methods exits, the modifier will be called.
1642 The return value of the modifier will be ignored.
1644 =item B<< $metaclass->add_around_method_modifier($method_name, $code) >>
1646 This wraps the specified method with the supplied subroutine
1649 The first argument passed to the modifier will be a subroutine
1650 reference to the wrapped method. The second argument is the object,
1651 and after that come any arguments passed when the method is called.
1653 The around modifier can choose to call the original method, as well as
1654 what arguments to pass if it does so.
1656 The return value of the modifier is what will be seen by the caller.
1660 =head2 Introspection
1664 =item B<< Class::MOP::Class->meta >>
1666 This will return a L<Class::MOP::Class> instance for this class.
1668 It should also be noted that L<Class::MOP> will actually bootstrap
1669 this module by installing a number of attribute meta-objects into its
1676 Stevan Little E<lt>stevan@iinteractive.comE<gt>
1678 =head1 COPYRIGHT AND LICENSE
1680 Copyright 2006-2009 by Infinity Interactive, Inc.
1682 L<http://www.iinteractive.com>
1684 This library is free software; you can redistribute it and/or modify
1685 it under the same terms as Perl itself.