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_02';
15 $VERSION = eval $VERSION;
16 our $AUTHORITY = 'cpan:STEVAN';
18 use base 'Class::MOP::Module';
28 $package_name = shift;
31 $package_name = $options{package};
34 (defined $package_name && $package_name && !ref($package_name))
35 || confess "You must pass a package name and it cannot be blessed";
37 return Class::MOP::get_metaclass_by_name($package_name)
38 || $class->construct_class_instance(package => $package_name, @_);
41 # NOTE: (meta-circularity)
42 # this is a special form of &construct_instance
43 # (see below), which is used to construct class
44 # meta-object instances for any Class::MOP::*
45 # class. All other classes will use the more
46 # normal &construct_instance.
47 sub construct_class_instance {
49 my $options = @_ == 1 ? $_[0] : {@_};
50 my $package_name = $options->{package};
51 (defined $package_name && $package_name)
52 || confess "You must pass a package name";
54 # return the metaclass if we have it cached,
55 # and it is still defined (it has not been
56 # reaped by DESTROY yet, which can happen
57 # annoyingly enough during global destruction)
59 if (defined(my $meta = Class::MOP::get_metaclass_by_name($package_name))) {
64 # we need to deal with the possibility
65 # of class immutability here, and then
66 # get the name of the class appropriately
68 ? ($class->is_immutable
69 ? $class->get_mutable_metaclass_name()
73 # now create the metaclass
75 if ($class eq 'Class::MOP::Class') {
76 $meta = $class->_new($options);
80 # it is safe to use meta here because
81 # class will always be a subclass of
82 # Class::MOP::Class, which defines meta
83 $meta = $class->meta->construct_instance($options)
86 # and check the metaclass compatibility
87 $meta->check_metaclass_compatibility();
89 Class::MOP::store_metaclass_by_name($package_name, $meta);
92 # we need to weaken any anon classes
93 # so that they can call DESTROY properly
94 Class::MOP::weaken_metaclass($package_name) if $meta->is_anon_class;
101 my $options = @_ == 1 ? $_[0] : {@_};
104 # inherited from Class::MOP::Package
105 'package' => $options->{package},
108 # since the following attributes will
109 # actually be loaded from the symbol
110 # table, and actually bypass the instance
111 # entirely, we can just leave these things
112 # listed here for reference, because they
113 # should not actually have a value associated
115 'namespace' => \undef,
117 # inherited from Class::MOP::Module
119 'authority' => \undef,
121 # defined in Class::MOP::Class
122 'superclasses' => \undef,
126 'attribute_metaclass' => $options->{'attribute_metaclass'}
127 || 'Class::MOP::Attribute',
128 'method_metaclass' => $options->{'method_metaclass'}
129 || 'Class::MOP::Method',
130 'wrapped_method_metaclass' => $options->{'wrapped_method_metaclass'}
131 || 'Class::MOP::Method::Wrapped',
132 'instance_metaclass' => $options->{'instance_metaclass'}
133 || 'Class::MOP::Instance',
137 sub reset_package_cache_flag { (shift)->{'_package_cache_flag'} = undef }
138 sub update_package_cache_flag {
141 # we can manually update the cache number
142 # since we are actually adding the method
143 # to our cache as well. This avoids us
144 # having to regenerate the method_map.
146 $self->{'_package_cache_flag'} = Class::MOP::check_package_cache_flag($self->name);
149 sub check_metaclass_compatibility {
152 # this is always okay ...
153 return if ref($self) eq 'Class::MOP::Class' &&
154 $self->instance_metaclass eq 'Class::MOP::Instance';
156 my @class_list = $self->linearized_isa;
157 shift @class_list; # shift off $self->name
159 foreach my $superclass_name (@class_list) {
160 my $super_meta = Class::MOP::get_metaclass_by_name($superclass_name) || next;
163 # we need to deal with the possibility
164 # of class immutability here, and then
165 # get the name of the class appropriately
167 = $super_meta->is_immutable
168 ? $super_meta->get_mutable_metaclass_name()
171 ($self->isa($super_meta_type))
172 || confess $self->name . "->meta => (" . (ref($self)) . ")" .
173 " is not compatible with the " .
174 $superclass_name . "->meta => (" . ($super_meta_type) . ")";
176 # we also need to check that instance metaclasses
177 # are compatibile in the same the class.
178 ($self->instance_metaclass->isa($super_meta->instance_metaclass))
179 || confess $self->name . "->meta->instance_metaclass => (" . ($self->instance_metaclass) . ")" .
180 " is not compatible with the " .
181 $superclass_name . "->meta->instance_metaclass => (" . ($super_meta->instance_metaclass) . ")";
189 # this should be sufficient, if you have a
190 # use case where it is not, write a test and
192 my $ANON_CLASS_SERIAL = 0;
195 # we need a sufficiently annoying prefix
196 # this should suffice for now, this is
197 # used in a couple of places below, so
198 # need to put it up here for now.
199 my $ANON_CLASS_PREFIX = 'Class::MOP::Class::__ANON__::SERIAL::';
203 no warnings 'uninitialized';
204 $self->name =~ /^$ANON_CLASS_PREFIX/;
207 sub create_anon_class {
208 my ($class, %options) = @_;
209 my $package_name = $ANON_CLASS_PREFIX . ++$ANON_CLASS_SERIAL;
210 return $class->create($package_name, %options);
214 # this will only get called for
215 # anon-classes, all other calls
216 # are assumed to occur during
217 # global destruction and so don't
218 # really need to be handled explicitly
222 return if Class::MOP::in_global_destruction(); # it'll happen soon anyway and this just makes things more complicated
224 no warnings 'uninitialized';
225 return unless $self->name =~ /^$ANON_CLASS_PREFIX/;
226 # Moose does a weird thing where it replaces the metaclass for
227 # class when fixing metaclass incompatibility. In that case,
228 # we don't want to clean out the namespace now. We can detect
229 # that because Moose will explicitly update the singleton
230 # cache in Class::MOP.
231 my $current_meta = Class::MOP::get_metaclass_by_name($self->name);
232 return if $current_meta ne $self;
234 my ($serial_id) = ($self->name =~ /^$ANON_CLASS_PREFIX(\d+)/);
236 foreach my $key (keys %{$ANON_CLASS_PREFIX . $serial_id}) {
237 delete ${$ANON_CLASS_PREFIX . $serial_id}{$key};
239 delete ${'main::' . $ANON_CLASS_PREFIX}{$serial_id . '::'};
244 # creating classes with MOP ...
247 my ( $class, @args ) = @_;
249 unshift @args, 'package' if @args % 2 == 1;
251 my (%options) = @args;
252 my $package_name = $options{package};
254 (ref $options{superclasses} eq 'ARRAY')
255 || confess "You must pass an ARRAY ref of superclasses"
256 if exists $options{superclasses};
258 (ref $options{attributes} eq 'ARRAY')
259 || confess "You must pass an ARRAY ref of attributes"
260 if exists $options{attributes};
262 (ref $options{methods} eq 'HASH')
263 || confess "You must pass a HASH ref of methods"
264 if exists $options{methods};
266 $class->SUPER::create(%options);
268 my (%initialize_options) = @args;
269 delete @initialize_options{qw(
277 my $meta = $class->initialize( $package_name => %initialize_options );
280 $meta->add_method('meta' => sub {
281 $class->initialize(ref($_[0]) || $_[0]);
284 $meta->superclasses(@{$options{superclasses}})
285 if exists $options{superclasses};
287 # process attributes first, so that they can
288 # install accessors, but locally defined methods
289 # can then overwrite them. It is maybe a little odd, but
290 # I think this should be the order of things.
291 if (exists $options{attributes}) {
292 foreach my $attr (@{$options{attributes}}) {
293 $meta->add_attribute($attr);
296 if (exists $options{methods}) {
297 foreach my $method_name (keys %{$options{methods}}) {
298 $meta->add_method($method_name, $options{methods}->{$method_name});
307 # all these attribute readers will be bootstrapped
308 # away in the Class::MOP bootstrap section
310 sub get_attribute_map { $_[0]->{'attributes'} }
311 sub attribute_metaclass { $_[0]->{'attribute_metaclass'} }
312 sub method_metaclass { $_[0]->{'method_metaclass'} }
313 sub wrapped_method_metaclass { $_[0]->{'wrapped_method_metaclass'} }
314 sub instance_metaclass { $_[0]->{'instance_metaclass'} }
316 # Instance Construction & Cloning
322 # we need to protect the integrity of the
323 # Class::MOP::Class singletons here, so we
324 # delegate this to &construct_class_instance
325 # which will deal with the singletons
326 return $class->construct_class_instance(@_)
327 if $class->name->isa('Class::MOP::Class');
328 return $class->construct_instance(@_);
331 sub construct_instance {
333 my $params = @_ == 1 ? $_[0] : {@_};
334 my $meta_instance = $class->get_meta_instance();
335 my $instance = $meta_instance->create_instance();
336 foreach my $attr ($class->compute_all_applicable_attributes()) {
337 $attr->initialize_instance_slot($meta_instance, $instance, $params);
340 # this will only work for a HASH instance type
341 if ($class->is_anon_class) {
342 (Scalar::Util::reftype($instance) eq 'HASH')
343 || confess "Currently only HASH based instances are supported with instance of anon-classes";
345 # At some point we should make this official
346 # as a reserved slot name, but right now I am
347 # going to keep it here.
348 # my $RESERVED_MOP_SLOT = '__MOP__';
349 $instance->{'__MOP__'} = $class;
355 sub get_meta_instance {
357 $self->{'_meta_instance'} ||= $self->create_meta_instance();
360 sub create_meta_instance {
363 my $instance = $self->instance_metaclass->new(
364 associated_metaclass => $self,
365 attributes => [ $self->compute_all_applicable_attributes() ],
368 $self->add_meta_instance_dependencies()
369 if $instance->is_dependent_on_superclasses();
376 my $instance = shift;
377 (blessed($instance) && $instance->isa($class->name))
378 || confess "You must pass an instance of the metaclass (" . (ref $class ? $class->name : $class) . "), not ($instance)";
381 # we need to protect the integrity of the
382 # Class::MOP::Class singletons here, they
383 # should not be cloned.
384 return $instance if $instance->isa('Class::MOP::Class');
385 $class->clone_instance($instance, @_);
389 my ($class, $instance, %params) = @_;
391 || confess "You can only clone instances, ($instance) is not a blessed instance";
392 my $meta_instance = $class->get_meta_instance();
393 my $clone = $meta_instance->clone_instance($instance);
394 foreach my $attr ($class->compute_all_applicable_attributes()) {
395 if ( defined( my $init_arg = $attr->init_arg ) ) {
396 if (exists $params{$init_arg}) {
397 $attr->set_value($clone, $params{$init_arg});
404 sub rebless_instance {
405 my ($self, $instance, %params) = @_;
408 if ($instance->can('meta')) {
409 ($instance->meta->isa('Class::MOP::Class'))
410 || confess 'Cannot rebless instance if ->meta is not an instance of Class::MOP::Class';
411 $old_metaclass = $instance->meta;
414 $old_metaclass = $self->initialize(blessed($instance));
417 $old_metaclass->rebless_instance_away($instance, $self, %params);
419 my $meta_instance = $self->get_meta_instance();
421 $self->name->isa($old_metaclass->name)
422 || confess "You may rebless only into a subclass of (". $old_metaclass->name ."), of which (". $self->name .") isn't.";
425 # we use $_[1] here because of t/306_rebless_overload.t regressions on 5.8.8
426 $meta_instance->rebless_instance_structure($_[1], $self);
428 foreach my $attr ( $self->compute_all_applicable_attributes ) {
429 if ( $attr->has_value($instance) ) {
430 if ( defined( my $init_arg = $attr->init_arg ) ) {
431 $params{$init_arg} = $attr->get_value($instance)
432 unless exists $params{$init_arg};
435 $attr->set_value($instance, $attr->get_value($instance));
440 foreach my $attr ($self->compute_all_applicable_attributes) {
441 $attr->initialize_instance_slot($meta_instance, $instance, \%params);
447 sub rebless_instance_away {
448 # this intentionally does nothing, it is just a hook
455 my $var_spec = { sigil => '@', type => 'ARRAY', name => 'ISA' };
458 @{$self->get_package_symbol($var_spec)} = @supers;
461 # on 5.8 and below, we need to call
462 # a method to get Perl to detect
463 # a cycle in the class hierarchy
464 my $class = $self->name;
468 # we need to check the metaclass
469 # compatibility here so that we can
470 # be sure that the superclass is
471 # not potentially creating an issues
472 # we don't know about
474 $self->check_metaclass_compatibility();
475 $self->update_meta_instance_dependencies();
477 @{$self->get_package_symbol($var_spec)};
483 my $super_class = $self->name;
485 if ( Class::MOP::HAVE_ISAREV() ) {
486 return @{ $super_class->mro::get_isarev() };
490 my $find_derived_classes;
491 $find_derived_classes = sub {
492 my ($outer_class) = @_;
494 my $symbol_table_hashref = do { no strict 'refs'; \%{"${outer_class}::"} };
497 for my $symbol ( keys %$symbol_table_hashref ) {
498 next SYMBOL if $symbol !~ /\A (\w+):: \z/x;
499 my $inner_class = $1;
501 next SYMBOL if $inner_class eq 'SUPER'; # skip '*::SUPER'
505 ? "${outer_class}::$inner_class"
508 if ( $class->isa($super_class) and $class ne $super_class ) {
509 push @derived_classes, $class;
512 next SYMBOL if $class eq 'main'; # skip 'main::*'
514 $find_derived_classes->($class);
518 my $root_class = q{};
519 $find_derived_classes->($root_class);
521 undef $find_derived_classes;
523 @derived_classes = sort { $a->isa($b) ? 1 : $b->isa($a) ? -1 : 0 } @derived_classes;
525 return @derived_classes;
531 return @{ mro::get_linear_isa( (shift)->name ) };
534 sub class_precedence_list {
536 my $name = $self->name;
538 unless (Class::MOP::IS_RUNNING_ON_5_10()) {
540 # We need to check for circular inheritance here
541 # if we are are not on 5.10, cause 5.8 detects it
542 # late. This will do nothing if all is well, and
543 # blow up otherwise. Yes, it's an ugly hack, better
544 # suggestions are welcome.
546 ($name || return)->isa('This is a test for circular inheritance')
549 # if our mro is c3, we can
550 # just grab the linear_isa
551 if (mro::get_mro($name) eq 'c3') {
552 return @{ mro::get_linear_isa($name) }
556 # we can't grab the linear_isa for dfs
557 # since it has all the duplicates
562 $self->initialize($_)->class_precedence_list()
563 } $self->superclasses()
570 sub wrap_method_body {
571 my ( $self, %args ) = @_;
573 ('CODE' eq ref $args{body})
574 || confess "Your code block must be a CODE reference";
576 $self->method_metaclass->wrap(
577 package_name => $self->name,
583 my ($self, $method_name, $method) = @_;
584 (defined $method_name && $method_name)
585 || confess "You must define a method name";
588 if (blessed($method)) {
589 $body = $method->body;
590 if ($method->package_name ne $self->name) {
591 $method = $method->clone(
592 package_name => $self->name,
594 ) if $method->can('clone');
599 $method = $self->wrap_method_body( body => $body, name => $method_name );
602 $method->attach_to_class($self);
604 # This used to call get_method_map, which meant we would build all
605 # the method objects for the class just because we added one
606 # method. This is hackier, but quicker too.
607 $self->{methods}{$method_name} = $method;
609 my $full_method_name = ($self->name . '::' . $method_name);
610 $self->add_package_symbol(
611 { sigil => '&', type => 'CODE', name => $method_name },
612 Class::MOP::subname($full_method_name => $body)
617 my $fetch_and_prepare_method = sub {
618 my ($self, $method_name) = @_;
619 my $wrapped_metaclass = $self->wrapped_method_metaclass;
621 my $method = $self->get_method($method_name);
622 # if we dont have local ...
624 # try to find the next method
625 $method = $self->find_next_method_by_name($method_name);
626 # die if it does not exist
628 || confess "The method '$method_name' was not found in the inheritance hierarchy for " . $self->name;
629 # and now make sure to wrap it
630 # even if it is already wrapped
631 # because we need a new sub ref
632 $method = $wrapped_metaclass->wrap($method);
635 # now make sure we wrap it properly
636 $method = $wrapped_metaclass->wrap($method)
637 unless $method->isa($wrapped_metaclass);
639 $self->add_method($method_name => $method);
643 sub add_before_method_modifier {
644 my ($self, $method_name, $method_modifier) = @_;
645 (defined $method_name && $method_name)
646 || confess "You must pass in a method name";
647 my $method = $fetch_and_prepare_method->($self, $method_name);
648 $method->add_before_modifier(
649 Class::MOP::subname(':before' => $method_modifier)
653 sub add_after_method_modifier {
654 my ($self, $method_name, $method_modifier) = @_;
655 (defined $method_name && $method_name)
656 || confess "You must pass in a method name";
657 my $method = $fetch_and_prepare_method->($self, $method_name);
658 $method->add_after_modifier(
659 Class::MOP::subname(':after' => $method_modifier)
663 sub add_around_method_modifier {
664 my ($self, $method_name, $method_modifier) = @_;
665 (defined $method_name && $method_name)
666 || confess "You must pass in a method name";
667 my $method = $fetch_and_prepare_method->($self, $method_name);
668 $method->add_around_modifier(
669 Class::MOP::subname(':around' => $method_modifier)
674 # the methods above used to be named like this:
675 # ${pkg}::${method}:(before|after|around)
676 # but this proved problematic when using one modifier
677 # to wrap multiple methods (something which is likely
678 # to happen pretty regularly IMO). So instead of naming
679 # it like this, I have chosen to just name them purely
680 # with their modifier names, like so:
681 # :(before|after|around)
682 # The fact is that in a stack trace, it will be fairly
683 # evident from the context what method they are attached
684 # to, and so don't need the fully qualified name.
690 $self->add_method(@_);
694 my ($self, $method_name) = @_;
695 (defined $method_name && $method_name)
696 || confess "You must define a method name";
698 exists $self->{methods}{$method_name} || exists $self->get_method_map->{$method_name};
702 my ($self, $method_name) = @_;
703 (defined $method_name && $method_name)
704 || confess "You must define a method name";
706 return $self->{methods}{$method_name} || $self->get_method_map->{$method_name};
710 my ($self, $method_name) = @_;
711 (defined $method_name && $method_name)
712 || confess "You must define a method name";
714 my $removed_method = delete $self->get_method_map->{$method_name};
716 $self->remove_package_symbol(
717 { sigil => '&', type => 'CODE', name => $method_name }
720 $removed_method->detach_from_class if $removed_method;
722 $self->update_package_cache_flag; # still valid, since we just removed the method from the map
724 return $removed_method;
727 sub get_method_list {
729 keys %{$self->get_method_map};
732 sub find_method_by_name {
733 my ($self, $method_name) = @_;
734 (defined $method_name && $method_name)
735 || confess "You must define a method name to find";
736 foreach my $class ($self->linearized_isa) {
737 # fetch the meta-class ...
738 my $meta = $self->initialize($class);
739 return $meta->get_method($method_name)
740 if $meta->has_method($method_name);
745 sub get_all_methods {
747 my %methods = map { %{ $self->initialize($_)->get_method_map } } reverse $self->linearized_isa;
748 return values %methods;
752 sub compute_all_applicable_methods {
756 class => $_->package_name,
757 code => $_, # sigh, overloading
759 } shift->get_all_methods(@_);
762 sub get_all_method_names {
765 grep { $uniq{$_}++ == 0 } map { $_->name } $self->get_all_methods;
768 sub find_all_methods_by_name {
769 my ($self, $method_name) = @_;
770 (defined $method_name && $method_name)
771 || confess "You must define a method name to find";
773 foreach my $class ($self->linearized_isa) {
774 # fetch the meta-class ...
775 my $meta = $self->initialize($class);
777 name => $method_name,
779 code => $meta->get_method($method_name)
780 } if $meta->has_method($method_name);
785 sub find_next_method_by_name {
786 my ($self, $method_name) = @_;
787 (defined $method_name && $method_name)
788 || confess "You must define a method name to find";
789 my @cpl = $self->linearized_isa;
790 shift @cpl; # discard ourselves
791 foreach my $class (@cpl) {
792 # fetch the meta-class ...
793 my $meta = $self->initialize($class);
794 return $meta->get_method($method_name)
795 if $meta->has_method($method_name);
804 # either we have an attribute object already
805 # or we need to create one from the args provided
806 my $attribute = blessed($_[0]) ? $_[0] : $self->attribute_metaclass->new(@_);
807 # make sure it is derived from the correct type though
808 ($attribute->isa('Class::MOP::Attribute'))
809 || confess "Your attribute must be an instance of Class::MOP::Attribute (or a subclass)";
811 # first we attach our new attribute
812 # because it might need certain information
813 # about the class which it is attached to
814 $attribute->attach_to_class($self);
816 # then we remove attributes of a conflicting
817 # name here so that we can properly detach
818 # the old attr object, and remove any
819 # accessors it would have generated
820 if ( $self->has_attribute($attribute->name) ) {
821 $self->remove_attribute($attribute->name);
823 $self->invalidate_meta_instances();
826 # then onto installing the new accessors
827 $self->get_attribute_map->{$attribute->name} = $attribute;
829 # invalidate package flag here
830 my $e = do { local $@; eval { $attribute->install_accessors() }; $@ };
832 $self->remove_attribute($attribute->name);
839 sub update_meta_instance_dependencies {
842 if ( $self->{meta_instance_dependencies} ) {
843 return $self->add_meta_instance_dependencies;
847 sub add_meta_instance_dependencies {
850 $self->remove_meta_instance_dependencies;
852 my @attrs = $self->compute_all_applicable_attributes();
855 my @classes = grep { not $seen{$_->name}++ } map { $_->associated_class } @attrs;
857 foreach my $class ( @classes ) {
858 $class->add_dependent_meta_instance($self);
861 $self->{meta_instance_dependencies} = \@classes;
864 sub remove_meta_instance_dependencies {
867 if ( my $classes = delete $self->{meta_instance_dependencies} ) {
868 foreach my $class ( @$classes ) {
869 $class->remove_dependent_meta_instance($self);
879 sub add_dependent_meta_instance {
880 my ( $self, $metaclass ) = @_;
881 push @{ $self->{dependent_meta_instances} }, $metaclass;
884 sub remove_dependent_meta_instance {
885 my ( $self, $metaclass ) = @_;
886 my $name = $metaclass->name;
887 @$_ = grep { $_->name ne $name } @$_ for $self->{dependent_meta_instances};
890 sub invalidate_meta_instances {
892 $_->invalidate_meta_instance() for $self, @{ $self->{dependent_meta_instances} };
895 sub invalidate_meta_instance {
897 undef $self->{_meta_instance};
901 my ($self, $attribute_name) = @_;
902 (defined $attribute_name && $attribute_name)
903 || confess "You must define an attribute name";
904 exists $self->get_attribute_map->{$attribute_name};
908 my ($self, $attribute_name) = @_;
909 (defined $attribute_name && $attribute_name)
910 || confess "You must define an attribute name";
911 return $self->get_attribute_map->{$attribute_name}
913 # this will return undef anyway, so no need ...
914 # if $self->has_attribute($attribute_name);
918 sub remove_attribute {
919 my ($self, $attribute_name) = @_;
920 (defined $attribute_name && $attribute_name)
921 || confess "You must define an attribute name";
922 my $removed_attribute = $self->get_attribute_map->{$attribute_name};
923 return unless defined $removed_attribute;
924 delete $self->get_attribute_map->{$attribute_name};
925 $self->invalidate_meta_instances();
926 $removed_attribute->remove_accessors();
927 $removed_attribute->detach_from_class();
928 return $removed_attribute;
931 sub get_attribute_list {
933 keys %{$self->get_attribute_map};
936 sub get_all_attributes {
937 shift->compute_all_applicable_attributes(@_);
940 sub compute_all_applicable_attributes {
942 my %attrs = map { %{ $self->initialize($_)->get_attribute_map } } reverse $self->linearized_isa;
943 return values %attrs;
946 sub find_attribute_by_name {
947 my ($self, $attr_name) = @_;
948 foreach my $class ($self->linearized_isa) {
949 # fetch the meta-class ...
950 my $meta = $self->initialize($class);
951 return $meta->get_attribute($attr_name)
952 if $meta->has_attribute($attr_name);
957 # check if we can reinitialize
961 # if any local attr is defined
962 return if $self->get_attribute_list;
964 # or any non-declared methods
965 if ( my @methods = values %{ $self->get_method_map } ) {
966 my $metaclass = $self->method_metaclass;
967 foreach my $method ( @methods ) {
968 return if $method->isa("Class::MOP::Method::Generated");
969 # FIXME do we need to enforce this too? return unless $method->isa($metaclass);
979 sub is_immutable { 0 }
981 sub immutable_transformer { $_[0]->{immutable_transformer} }
982 sub _set_immutable_transformer { $_[0]->{immutable_transformer} = $_[1] }
987 return if $self->is_immutable;
989 my $transformer = $self->immutable_transformer
990 || $self->_make_immutable_transformer(@_);
992 $self->_set_immutable_transformer($transformer);
994 $transformer->make_metaclass_immutable;
998 my %Default_Immutable_Options = (
999 read_only => [qw/superclasses/],
1007 remove_package_symbol
1011 class_precedence_list => 'ARRAY',
1012 # FIXME perl 5.10 memoizes this on its own, no need?
1013 linearized_isa => 'ARRAY',
1014 get_all_methods => 'ARRAY',
1015 get_all_method_names => 'ARRAY',
1016 compute_all_applicable_attributes => 'ARRAY',
1017 get_meta_instance => 'SCALAR',
1018 get_method_map => 'SCALAR',
1022 # this is ugly, but so are typeglobs,
1023 # so whattayahgonnadoboutit
1026 add_package_symbol => sub {
1027 my $original = shift;
1028 confess "Cannot add package symbols to an immutable metaclass"
1029 unless ( caller(2) )[3] eq
1030 'Class::MOP::Package::get_package_symbol';
1032 # This is a workaround for a bug in 5.8.1 which thinks that
1033 # goto $original->body
1034 # is trying to go to a label
1035 my $body = $original->body;
1041 sub _default_immutable_transformer_options {
1042 return %Default_Immutable_Options;
1046 sub _make_immutable_transformer {
1049 Class::MOP::Immutable->new(
1051 $self->_default_immutable_transformer_options,
1059 return if $self->is_mutable;
1061 $self->immutable_transformer->make_metaclass_mutable;
1072 Class::MOP::Class - Class Meta Object
1076 # assuming that class Foo
1077 # has been defined, you can
1079 # use this for introspection ...
1081 # add a method to Foo ...
1082 Foo->meta->add_method( 'bar' => sub {...} )
1084 # get a list of all the classes searched
1085 # the method dispatcher in the correct order
1086 Foo->meta->class_precedence_list()
1088 # remove a method from Foo
1089 Foo->meta->remove_method('bar');
1091 # or use this to actually create classes ...
1093 Class::MOP::Class->create(
1096 superclasses => ['Foo'],
1098 Class::MOP:: : Attribute->new('$bar'),
1099 Class::MOP:: : Attribute->new('$baz'),
1102 calculate_bar => sub {...},
1103 construct_baz => sub {...}
1110 The Class Protocol is the largest and most complex part of the
1111 Class::MOP meta-object protocol. It controls the introspection and
1112 manipulation of Perl 5 classes, and it can create them as well. The
1113 best way to understand what this module can do, is to read the
1114 documentation for each of its methods.
1118 C<Class::MOP::Class> is a subclass of L<Class::MOP::Module>.
1122 =head2 Class construction
1124 These methods all create new C<Class::MOP::Class> objects. These
1125 objects can represent existing classes, or they can be used to create
1126 new classes from scratch.
1128 The metaclass object for a given class is a singleton. If you attempt
1129 to create a metaclass for the same class twice, you will just get the
1134 =item B<< Class::MOP::Class->create($package_name, %options) >>
1136 This method creates a new C<Class::MOP::Class> object with the given
1137 package name. It accepts a number of options.
1143 An optional version number for the newly created package.
1147 An optional authority for the newly created package.
1149 =item * superclasses
1151 An optional array reference of superclass names.
1155 An optional hash reference of methods for the class. The keys of the
1156 hash reference are method names, and values are subroutine references.
1160 An optional array reference of attributes.
1162 An attribute can be passed as an existing L<Class::MOP::Attribute>
1163 object, I<or> or as a hash reference of options which will be passed
1164 to the attribute metaclass's constructor.
1168 =item B<< Class::MOP::Class->create_anon_class(%options) >>
1170 This method works just like C<< Class::MOP::Class->create >> but it
1171 creates an "anonymous" class. In fact, the class does have a name, but
1172 that name is a unique name generated internally by this module.
1174 It accepts the same C<superclasses>, C<methods>, and C<attributes>
1175 parameters that C<create> accepts.
1177 Anonymous classes are destroyed once the metaclass they are attached
1178 to goes out of scope, and will be removed from Perl's internal symbol
1181 All instances of an anonymous class keep a special reference to the
1182 metaclass object, which prevents the metaclass from going out of scope
1183 while any instances exist.
1185 This only works if the instance if based on a hash reference, however.
1187 =item B<< Class::MOP::Class->initialize($package_name, %options) >>
1189 This method will initialize a C<Class::MOP::Class> object for the
1190 named package. Unlike C<create>, this method I<will not> create a new
1193 The purpose of this method is to retrieve a C<Class::MOP::Class>
1194 object for introspecting an existing class.
1196 If an existing C<Class::MOP::Class> object exists for the named
1197 package, it will be returned, and any options provided will be
1200 If the object does not yet exist, it will be created.
1202 The valid options that can be passed to this method are
1203 C<attribute_metaclass>, C<method_metaclass>,
1204 C<wrapped_method_metaclass>, and C<instance_metaclass>. These are all
1205 optional, and default to the appropriate class in the C<Class::MOP>
1210 =head2 Object instance construction and cloning
1212 These methods are all related to creating and/or cloning object
1217 =item B<< $metaclass->clone_object($instance, %params) >>
1219 This method clones an existing object instance. Any parameters you
1220 provide are will override existing attribute values in the object.
1222 This is a convenience method for cloning an object instance, then
1223 blessing it into the appropriate package.
1225 You could implement a clone method in your class, using this method:
1228 my ($self, %params) = @_;
1229 $self->meta->clone_object($self, %params);
1232 =item B<< $metaclass->rebless_instance($instance, %params) >>
1234 This method changes the class of C<$instance> to the metaclass's class.
1236 You can only rebless an instance into a subclass of its current
1237 class. If you pass any additional parameters, these will be treated
1238 like constructor parameters and used to initialize the object's
1239 attributes. Any existing attributes that are already set will be
1242 Before reblessing the instance, this method will call
1243 C<rebless_instance_away> on the instance's current metaclass. This method
1244 will be passed the instance, the new metaclass, and any parameters
1245 specified to C<rebless_instance>. By default, C<rebless_instance_away>
1246 does nothing; it is merely a hook.
1248 =item B<< $metaclass->new_object(%params) >>
1250 This method is used to create a new object of the metaclass's
1251 class. Any parameters you provide are used to initialize the
1252 instance's attributes.
1254 =item B<< $metaclass->instance_metaclass >>
1256 Returns the class name of the instance metaclass, see
1257 L<Class::MOP::Instance> for more information on the instance
1260 =item B<< $metaclass->get_meta_instance >>
1262 Returns an instance of the C<instance_metaclass> to be used in the
1263 construction of a new instance of the class.
1267 =head2 Informational predicates
1269 These are a few predicate methods for asking information about the
1274 =item B<< $metaclass->is_anon_class >>
1276 This returns true if the class was created by calling C<<
1277 Class::MOP::Class->create_anon_class >>.
1279 =item B<< $metaclass->is_mutable >>
1281 This returns true if the class is still mutable.
1283 =item B<< $metaclass->is_immutable >>
1285 This returns true if the class has been made immutable.
1287 =item B<< $metaclass->is_pristine >>
1289 A class is I<not> pristine if it has non-inherited attributes or if it
1290 has any generated methods.
1294 =head2 Inheritance Relationships
1298 =item B<< $metaclass->superclasses(@superclasses) >>
1300 This is a read-write accessor which represents the superclass
1301 relationships of the metaclass's class.
1303 This is basically sugar around getting and setting C<@ISA>.
1305 =item B<< $metaclass->class_precedence_list >>
1307 This returns a list of all of the class's ancestor classes. The
1308 classes are returned in method dispatch order.
1310 =item B<< $metaclass->linearized_isa >>
1312 This returns a list based on C<class_precedence_list> but with all
1315 =item B<< $metaclass->subclasses >>
1317 This returns a list of subclasses for this class.
1321 =head2 Method introspection and creation
1323 These methods allow you to introspect a class's methods, as well as
1324 add, remove, or change methods.
1326 Determining what is truly a method in a Perl 5 class requires some
1327 heuristics (aka guessing).
1329 Methods defined outside the package with a fully qualified name (C<sub
1330 Package::name { ... }>) will be included. Similarly, methods named
1331 with a fully qualified name using L<Sub::Name> are also included.
1333 However, we attempt to ignore imported functions.
1335 Ultimately, we are using heuristics to determine what truly is a
1336 method in a class, and these heuristics may get the wrong answer in
1337 some edge cases. However, for most "normal" cases the heuristics work
1342 =item B<< $metaclass->get_method($method_name) >>
1344 This will return a L<Class::MOP::Method> for the specified
1345 C<$method_name>. If the class does not have the specified method, it
1348 =item B<< $metaclass->has_method($method_name) >>
1350 Returns a boolean indicating whether or not the class defines the
1351 named method. It does not include methods inherited from parent
1354 =item B<< $metaclass->get_method_map >>
1356 Returns a hash reference representing the methods defined in this
1357 class. The keys are method names and the values are
1358 L<Class::MOP::Method> objects.
1360 =item B<< $metaclass->get_method_list >>
1362 This will return a list of method I<names> for all methods defined in
1365 =item B<< $metaclass->get_all_methods >>
1367 This will traverse the inheritance hierarchy and return a list of all
1368 the L<Class::MOP::Method> objects for this class and its parents.
1370 =item B<< $metaclass->find_method_by_name($method_name) >>
1372 This will return a L<Class::MOP::Method> for the specified
1373 C<$method_name>. If the class does not have the specified method, it
1376 Unlike C<get_method>, this method I<will> look for the named method in
1379 =item B<< $metaclass->get_all_method_names >>
1381 This will return a list of method I<names> for all of this class's
1382 methods, including inherited methods.
1384 =item B<< $metaclass->find_all_methods_by_name($method_name) >>
1386 This method looks for the named method in the class and all of its
1387 parents. It returns every matching method it finds in the inheritance
1388 tree, so it returns a list of methods.
1390 Each method is returned as a hash reference with three keys. The keys
1391 are C<name>, C<class>, and C<code>. The C<code> key has a
1392 L<Class::MOP::Method> object as its value.
1394 The list of methods is distinct.
1396 =item B<< $metaclass->find_next_method_by_name($method_name) >>
1398 This method returns the first method in any superclass matching the
1399 given name. It is effectively the method that C<SUPER::$method_name>
1402 =item B<< $metaclass->add_method($method_name, $method) >>
1404 This method takes a method name and a subroutine reference, and adds
1405 the method to the class.
1407 The subroutine reference can be a L<Class::MOP::Method>, and you are
1408 strongly encouraged to pass a meta method object instead of a code
1409 reference. If you do so, that object gets stored as part of the
1410 class's method map directly. If not, the meta information will have to
1411 be recreated later, and may be incorrect.
1413 If you provide a method object, this method will clone that object if
1414 the object's package name does not match the class name. This lets us
1415 track the original source of any methods added from other classes
1416 (notably Moose roles).
1418 =item B<< $metaclass->remove_method($method_name) >>
1420 Remove the named method from the class. This method returns the
1421 L<Class::MOP::Method> object for the method.
1423 =item B<< $metaclass->method_metaclass >>
1425 Returns the class name of the method metaclass, see
1426 L<Class::MOP::Method> for more information on the method metaclass.
1428 =item B<< $metaclass->wrapped_method_metaclass >>
1430 Returns the class name of the wrapped method metaclass, see
1431 L<Class::MOP::Method::Wrapped> for more information on the wrapped
1436 =head2 Attribute introspection and creation
1438 Because Perl 5 does not have a core concept of attributes in classes,
1439 we can only return information about attributes which have been added
1440 via this class's methods. We cannot discover information about
1441 attributes which are defined in terms of "regular" Perl 5 methods.
1445 =item B<< $metaclass->get_attribute($attribute_name) >>
1447 This will return a L<Class::MOP::Attribute> for the specified
1448 C<$attribute_name>. If the class does not have the specified
1449 attribute, it returns C<undef>
1451 =item B<< $metaclass->has_attribute($attribute_name) >>
1453 Returns a boolean indicating whether or not the class defines the
1454 named attribute. It does not include attributes inherited from parent
1457 =item B<< $metaclass->get_attribute_map >>
1459 Returns a hash reference representing the attributes defined in this
1460 class. The keys are attribute names and the values are
1461 L<Class::MOP::Attribute> objects.
1463 =item B<< $metaclass->get_attribute_list >>
1465 This will return a list of attributes I<names> for all attributes
1466 defined in this class.
1468 =item B<< $metaclass->get_all_attributes >>
1470 This will traverse the inheritance hierarchy and return a list of all
1471 the L<Class::MOP::Attribute> objects for this class and its parents.
1473 This method can also be called as C<compute_all_applicable_attributes>.
1475 =item B<< $metaclass->find_attribute_by_name($attribute_name) >>
1477 This will return a L<Class::MOP::Attribute> for the specified
1478 C<$attribute_name>. If the class does not have the specified
1479 attribute, it returns C<undef>
1481 Unlike C<get_attribute>, this attribute I<will> look for the named
1482 attribute in superclasses.
1484 =item B<< $metaclass->add_attribute(...) >>
1486 This method accepts either an existing L<Class::MOP::Attribute>
1487 object, or parameters suitable for passing to that class's C<new>
1490 The attribute provided will be added to the class.
1492 Any accessor methods defined by the attribute will be added to the
1493 class when the attribute is added.
1495 If an attribute of the same name already exists, the old attribute
1496 will be removed first.
1498 =item B<< $metaclass->remove_attribute($attribute_name) >>
1500 This will remove the named attribute from the class, and
1501 L<Class::MOP::Attribute> object.
1503 Removing an attribute also removes any accessor methods defined by the
1506 However, note that removing an attribute will only affect I<future>
1507 object instances created for this class, not existing instances.
1509 =item B<< $metaclass->attribute_metaclass >>
1511 Returns the class name of the attribute metaclass for this class. By
1512 default, this is L<Class::MOP::Attribute>. for more information on
1516 =head2 Class Immutability
1518 Making a class immutable "freezes" the class definition. You can no
1519 longer call methods which alter the class, such as adding or removing
1520 methods or attributes.
1522 Making a class immutable lets us optimize the class by inlining some
1523 methods, and also allows us to optimize some methods on the metaclass
1526 The immutabilization system in L<Moose> takes much greater advantage
1527 of the inlining features than Class::MOP itself does.
1531 =item B<< $metaclass->make_immutable(%options) >>
1533 This method will create an immutable transformer and uses it to make
1534 the class and its metaclass object immutable.
1536 Details of how immutabilization works are in L<Class::MOP::Immutable>
1539 =item B<< $metaclass->make_mutable >>
1541 Calling this method reverse the immutabilization transformation.
1543 =item B<< $metaclass->immutable_transformer >>
1545 If the class has been made immutable previously, this returns the
1546 L<Class::MOP::Immutable> object that was created to do the
1549 If the class was never made immutable, this method will die.
1553 =head2 Method Modifiers
1555 Method modifiers are hooks which allow a method to be wrapped with
1556 I<before>, I<after> and I<around> method modifiers. Every time a
1557 method is called, it's modifiers are also called.
1559 A class can modify its own methods, as well as methods defined in
1562 =head3 How method modifiers work?
1564 Method modifiers work by wrapping the original method and then
1565 replacing it in the class's symbol table. The wrappers will handle
1566 calling all the modifiers in the appropriate order and preserving the
1567 calling context for the original method.
1569 The return values of C<before> and C<after> modifiers are
1570 ignored. This is because their purpose is B<not> to filter the input
1571 and output of the primary method (this is done with an I<around>
1574 This may seem like an odd restriction to some, but doing this allows
1575 for simple code to be added at the beginning or end of a method call
1576 without altering the function of the wrapped method or placing any
1577 extra responsibility on the code of the modifier.
1579 Of course if you have more complex needs, you can use the C<around>
1580 modifier which allows you to change both the parameters passed to the
1581 wrapped method, as well as its return value.
1583 Before and around modifiers are called in last-defined-first-called
1584 order, while after modifiers are called in first-defined-first-called
1585 order. So the call tree might looks something like this:
1597 =head3 What is the performance impact?
1599 Of course there is a performance cost associated with method
1600 modifiers, but we have made every effort to make that cost directly
1601 proportional to the number of modifier features you utilize.
1603 The wrapping method does it's best to B<only> do as much work as it
1604 absolutely needs to. In order to do this we have moved some of the
1605 performance costs to set-up time, where they are easier to amortize.
1607 All this said, our benchmarks have indicated the following:
1609 simple wrapper with no modifiers 100% slower
1610 simple wrapper with simple before modifier 400% slower
1611 simple wrapper with simple after modifier 450% slower
1612 simple wrapper with simple around modifier 500-550% slower
1613 simple wrapper with all 3 modifiers 1100% slower
1615 These numbers may seem daunting, but you must remember, every feature
1616 comes with some cost. To put things in perspective, just doing a
1617 simple C<AUTOLOAD> which does nothing but extract the name of the
1618 method called and return it costs about 400% over a normal method
1623 =item B<< $metaclass->add_before_method_modifier($method_name, $code) >>
1625 This wraps the specified method with the supplied subroutine
1626 reference. The modifier will be called as a method itself, and will
1627 receive the same arguments as are passed to the method.
1629 When the modifier exits, the wrapped method will be called.
1631 The return value of the modifier will be ignored.
1633 =item B<< $metaclass->add_after_method_modifier($method_name, $code) >>
1635 This wraps the specified method with the supplied subroutine
1636 reference. The modifier will be called as a method itself, and will
1637 receive the same arguments as are passed to the method.
1639 When the wrapped methods exits, the modifier will be called.
1641 The return value of the modifier will be ignored.
1643 =item B<< $metaclass->add_around_method_modifier($method_name, $code) >>
1645 This wraps the specified method with the supplied subroutine
1648 The first argument passed to the modifier will be a subroutine
1649 reference to the wrapped method. The second argument is the object,
1650 and after that come any arguments passed when the method is called.
1652 The around modifier can choose to call the original method, as well as
1653 what arguments to pass if it does so.
1655 The return value of the modifier is what will be seen by the caller.
1659 =head2 Introspection
1663 =item B<< Class::MOP::Class->meta >>
1665 This will return a L<Class::MOP::Class> instance for this class.
1667 It should also be noted that L<Class::MOP> will actually bootstrap
1668 this module by installing a number of attribute meta-objects into its
1675 Stevan Little E<lt>stevan@iinteractive.comE<gt>
1677 =head1 COPYRIGHT AND LICENSE
1679 Copyright 2006-2009 by Infinity Interactive, Inc.
1681 L<http://www.iinteractive.com>
1683 This library is free software; you can redistribute it and/or modify
1684 it under the same terms as Perl itself.