2 package Class::MOP::Class;
7 use Class::MOP::Instance;
8 use Class::MOP::Method::Wrapped;
9 use Class::MOP::Method::Accessor;
10 use Class::MOP::Method::Constructor;
11 use Class::MOP::Class::Immutable::Class::MOP::Class;
14 use Scalar::Util 'blessed', 'weaken';
15 use Sub::Name 'subname';
16 use Devel::GlobalDestruction 'in_global_destruction';
18 our $VERSION = '0.85';
19 $VERSION = eval $VERSION;
20 our $AUTHORITY = 'cpan:STEVAN';
22 use base 'Class::MOP::Module';
32 $package_name = shift;
35 $package_name = $options{package};
38 (defined $package_name && $package_name && !ref($package_name))
39 || confess "You must pass a package name and it cannot be blessed";
41 return Class::MOP::get_metaclass_by_name($package_name)
42 || $class->_construct_class_instance(package => $package_name, @_);
45 sub construct_class_instance {
46 Carp::cluck('The construct_class_instance method has been made private.'
47 . " The public version is deprecated and will be removed in a future release.\n");
48 shift->_construct_class_instance(@_);
51 # NOTE: (meta-circularity)
52 # this is a special form of _construct_instance
53 # (see below), which is used to construct class
54 # meta-object instances for any Class::MOP::*
55 # class. All other classes will use the more
56 # normal &construct_instance.
57 sub _construct_class_instance {
59 my $options = @_ == 1 ? $_[0] : {@_};
60 my $package_name = $options->{package};
61 (defined $package_name && $package_name)
62 || confess "You must pass a package name";
64 # return the metaclass if we have it cached,
65 # and it is still defined (it has not been
66 # reaped by DESTROY yet, which can happen
67 # annoyingly enough during global destruction)
69 if (defined(my $meta = Class::MOP::get_metaclass_by_name($package_name))) {
74 # we need to deal with the possibility
75 # of class immutability here, and then
76 # get the name of the class appropriately
78 ? ($class->is_immutable
79 ? $class->get_mutable_metaclass_name()
83 # now create the metaclass
85 if ($class eq 'Class::MOP::Class') {
86 $meta = $class->_new($options);
90 # it is safe to use meta here because
91 # class will always be a subclass of
92 # Class::MOP::Class, which defines meta
93 $meta = $class->meta->_construct_instance($options)
96 # and check the metaclass compatibility
97 $meta->_check_metaclass_compatibility();
99 Class::MOP::store_metaclass_by_name($package_name, $meta);
102 # we need to weaken any anon classes
103 # so that they can call DESTROY properly
104 Class::MOP::weaken_metaclass($package_name) if $meta->is_anon_class;
111 my $options = @_ == 1 ? $_[0] : {@_};
114 # inherited from Class::MOP::Package
115 'package' => $options->{package},
118 # since the following attributes will
119 # actually be loaded from the symbol
120 # table, and actually bypass the instance
121 # entirely, we can just leave these things
122 # listed here for reference, because they
123 # should not actually have a value associated
125 'namespace' => \undef,
127 # inherited from Class::MOP::Module
129 'authority' => \undef,
131 # defined in Class::MOP::Class
132 'superclasses' => \undef,
136 'attribute_metaclass' =>
137 ( $options->{'attribute_metaclass'} || 'Class::MOP::Attribute' ),
138 'method_metaclass' =>
139 ( $options->{'method_metaclass'} || 'Class::MOP::Method' ),
140 'wrapped_method_metaclass' => (
141 $options->{'wrapped_method_metaclass'}
142 || 'Class::MOP::Method::Wrapped'
144 'instance_metaclass' =>
145 ( $options->{'instance_metaclass'} || 'Class::MOP::Instance' ),
146 'immutable_trait' => (
147 $options->{'immutable_trait'}
148 || 'Class::MOP::Class::Immutable::Trait'
150 'constructor_name' => ( $options->{constructor_name} || 'new' ),
151 'constructor_class' => (
152 $options->{constructor_class} || 'Class::MOP::Method::Constructor'
154 'destructor_class' => $options->{destructor_class},
158 sub reset_package_cache_flag { (shift)->{'_package_cache_flag'} = undef }
159 sub update_package_cache_flag {
162 # we can manually update the cache number
163 # since we are actually adding the method
164 # to our cache as well. This avoids us
165 # having to regenerate the method_map.
167 $self->{'_package_cache_flag'} = Class::MOP::check_package_cache_flag($self->name);
171 sub check_metaclass_compatibility {
172 Carp::cluck('The check_metaclass_compatibility method has been made private.'
173 . " The public version is deprecated and will be removed in a future release.\n");
174 shift->_check_metaclass_compatibility(@_);
177 sub _check_metaclass_compatibility {
180 # this is always okay ...
181 return if ref($self) eq 'Class::MOP::Class' &&
182 $self->instance_metaclass eq 'Class::MOP::Instance';
184 my @class_list = $self->linearized_isa;
185 shift @class_list; # shift off $self->name
187 foreach my $superclass_name (@class_list) {
188 my $super_meta = Class::MOP::get_metaclass_by_name($superclass_name) || next;
191 # we need to deal with the possibility
192 # of class immutability here, and then
193 # get the name of the class appropriately
195 = $super_meta->is_immutable
196 ? $super_meta->get_mutable_metaclass_name()
199 ($self->isa($super_meta_type))
200 || confess "Class::MOP::class_of(" . $self->name . ") => ("
201 . (ref($self)) . ")" . " is not compatible with the " .
202 "Class::MOP::class_of(".$superclass_name . ") => ("
203 . ($super_meta_type) . ")";
205 # we also need to check that instance metaclasses
206 # are compatibile in the same the class.
207 ($self->instance_metaclass->isa($super_meta->instance_metaclass))
208 || confess "Class::MOP::class_of(" . $self->name . ")->instance_metaclass => (" . ($self->instance_metaclass) . ")" .
209 " is not compatible with the " .
210 "Class::MOP::class_of(" . $superclass_name . ")->instance_metaclass => (" . ($super_meta->instance_metaclass) . ")";
218 # this should be sufficient, if you have a
219 # use case where it is not, write a test and
221 my $ANON_CLASS_SERIAL = 0;
224 # we need a sufficiently annoying prefix
225 # this should suffice for now, this is
226 # used in a couple of places below, so
227 # need to put it up here for now.
228 my $ANON_CLASS_PREFIX = 'Class::MOP::Class::__ANON__::SERIAL::';
232 no warnings 'uninitialized';
233 $self->name =~ /^$ANON_CLASS_PREFIX/;
236 sub create_anon_class {
237 my ($class, %options) = @_;
238 my $package_name = $ANON_CLASS_PREFIX . ++$ANON_CLASS_SERIAL;
239 return $class->create($package_name, %options);
243 # this will only get called for
244 # anon-classes, all other calls
245 # are assumed to occur during
246 # global destruction and so don't
247 # really need to be handled explicitly
251 return if in_global_destruction(); # it'll happen soon anyway and this just makes things more complicated
253 no warnings 'uninitialized';
254 return unless $self->name =~ /^$ANON_CLASS_PREFIX/;
255 # Moose does a weird thing where it replaces the metaclass for
256 # class when fixing metaclass incompatibility. In that case,
257 # we don't want to clean out the namespace now. We can detect
258 # that because Moose will explicitly update the singleton
259 # cache in Class::MOP.
260 my $current_meta = Class::MOP::get_metaclass_by_name($self->name);
261 return if $current_meta ne $self;
263 my ($serial_id) = ($self->name =~ /^$ANON_CLASS_PREFIX(\d+)/);
265 foreach my $key (keys %{$ANON_CLASS_PREFIX . $serial_id}) {
266 delete ${$ANON_CLASS_PREFIX . $serial_id}{$key};
268 delete ${'main::' . $ANON_CLASS_PREFIX}{$serial_id . '::'};
273 # creating classes with MOP ...
276 my ( $class, @args ) = @_;
278 unshift @args, 'package' if @args % 2 == 1;
280 my (%options) = @args;
281 my $package_name = $options{package};
283 (ref $options{superclasses} eq 'ARRAY')
284 || confess "You must pass an ARRAY ref of superclasses"
285 if exists $options{superclasses};
287 (ref $options{attributes} eq 'ARRAY')
288 || confess "You must pass an ARRAY ref of attributes"
289 if exists $options{attributes};
291 (ref $options{methods} eq 'HASH')
292 || confess "You must pass a HASH ref of methods"
293 if exists $options{methods};
295 my (%initialize_options) = @args;
296 delete @initialize_options{qw(
304 my $meta = $class->initialize( $package_name => %initialize_options );
306 $meta->_instantiate_module( $options{version}, $options{authority} );
309 $meta->add_method('meta' => sub {
310 $class->initialize(ref($_[0]) || $_[0]);
313 $meta->superclasses(@{$options{superclasses}})
314 if exists $options{superclasses};
316 # process attributes first, so that they can
317 # install accessors, but locally defined methods
318 # can then overwrite them. It is maybe a little odd, but
319 # I think this should be the order of things.
320 if (exists $options{attributes}) {
321 foreach my $attr (@{$options{attributes}}) {
322 $meta->add_attribute($attr);
325 if (exists $options{methods}) {
326 foreach my $method_name (keys %{$options{methods}}) {
327 $meta->add_method($method_name, $options{methods}->{$method_name});
336 # all these attribute readers will be bootstrapped
337 # away in the Class::MOP bootstrap section
339 sub get_attribute_map { $_[0]->{'attributes'} }
340 sub attribute_metaclass { $_[0]->{'attribute_metaclass'} }
341 sub method_metaclass { $_[0]->{'method_metaclass'} }
342 sub wrapped_method_metaclass { $_[0]->{'wrapped_method_metaclass'} }
343 sub instance_metaclass { $_[0]->{'instance_metaclass'} }
344 sub immutable_trait { $_[0]->{'immutable_trait'} }
345 sub constructor_class { $_[0]->{'constructor_class'} }
346 sub constructor_name { $_[0]->{'constructor_name'} }
347 sub destructor_class { $_[0]->{'destructor_class'} }
349 # Instance Construction & Cloning
355 # we need to protect the integrity of the
356 # Class::MOP::Class singletons here, so we
357 # delegate this to &construct_class_instance
358 # which will deal with the singletons
359 return $class->_construct_class_instance(@_)
360 if $class->name->isa('Class::MOP::Class');
361 return $class->_construct_instance(@_);
364 sub construct_instance {
365 Carp::cluck('The construct_instance method has been made private.'
366 . " The public version is deprecated and will be removed in a future release.\n");
367 shift->_construct_instance(@_);
370 sub _construct_instance {
372 my $params = @_ == 1 ? $_[0] : {@_};
373 my $meta_instance = $class->get_meta_instance();
374 my $instance = $meta_instance->create_instance();
375 foreach my $attr ($class->get_all_attributes()) {
376 $attr->initialize_instance_slot($meta_instance, $instance, $params);
379 # this will only work for a HASH instance type
380 if ($class->is_anon_class) {
381 (Scalar::Util::reftype($instance) eq 'HASH')
382 || confess "Currently only HASH based instances are supported with instance of anon-classes";
384 # At some point we should make this official
385 # as a reserved slot name, but right now I am
386 # going to keep it here.
387 # my $RESERVED_MOP_SLOT = '__MOP__';
388 $instance->{'__MOP__'} = $class;
394 sub get_meta_instance {
396 $self->{'_meta_instance'} ||= $self->_create_meta_instance();
399 sub create_meta_instance {
400 Carp::cluck('The create_meta_instance method has been made private.'
401 . " The public version is deprecated and will be removed in a future release.\n");
402 shift->_create_meta_instance(@_);
405 sub _create_meta_instance {
408 my $instance = $self->instance_metaclass->new(
409 associated_metaclass => $self,
410 attributes => [ $self->get_all_attributes() ],
413 $self->add_meta_instance_dependencies()
414 if $instance->is_dependent_on_superclasses();
421 my $instance = shift;
422 (blessed($instance) && $instance->isa($class->name))
423 || confess "You must pass an instance of the metaclass (" . (ref $class ? $class->name : $class) . "), not ($instance)";
426 # we need to protect the integrity of the
427 # Class::MOP::Class singletons here, they
428 # should not be cloned.
429 return $instance if $instance->isa('Class::MOP::Class');
430 $class->_clone_instance($instance, @_);
434 Carp::cluck('The clone_instance method has been made private.'
435 . " The public version is deprecated and will be removed in a future release.\n");
436 shift->_clone_instance(@_);
439 sub _clone_instance {
440 my ($class, $instance, %params) = @_;
442 || confess "You can only clone instances, ($instance) is not a blessed instance";
443 my $meta_instance = $class->get_meta_instance();
444 my $clone = $meta_instance->clone_instance($instance);
445 foreach my $attr ($class->get_all_attributes()) {
446 if ( defined( my $init_arg = $attr->init_arg ) ) {
447 if (exists $params{$init_arg}) {
448 $attr->set_value($clone, $params{$init_arg});
455 sub rebless_instance {
456 my ($self, $instance, %params) = @_;
458 my $old_metaclass = Class::MOP::class_of($instance);
460 my $old_class = $old_metaclass ? $old_metaclass->name : blessed($instance);
461 $self->name->isa($old_class)
462 || confess "You may rebless only into a subclass of ($old_class), of which (". $self->name .") isn't.";
464 $old_metaclass->rebless_instance_away($instance, $self, %params)
467 my $meta_instance = $self->get_meta_instance();
470 # we use $_[1] here because of t/306_rebless_overload.t regressions on 5.8.8
471 $meta_instance->rebless_instance_structure($_[1], $self);
473 foreach my $attr ( $self->get_all_attributes ) {
474 if ( $attr->has_value($instance) ) {
475 if ( defined( my $init_arg = $attr->init_arg ) ) {
476 $params{$init_arg} = $attr->get_value($instance)
477 unless exists $params{$init_arg};
480 $attr->set_value($instance, $attr->get_value($instance));
485 foreach my $attr ($self->get_all_attributes) {
486 $attr->initialize_instance_slot($meta_instance, $instance, \%params);
492 sub rebless_instance_away {
493 # this intentionally does nothing, it is just a hook
500 my $var_spec = { sigil => '@', type => 'ARRAY', name => 'ISA' };
503 @{$self->get_package_symbol($var_spec)} = @supers;
506 # on 5.8 and below, we need to call
507 # a method to get Perl to detect
508 # a cycle in the class hierarchy
509 my $class = $self->name;
513 # we need to check the metaclass
514 # compatibility here so that we can
515 # be sure that the superclass is
516 # not potentially creating an issues
517 # we don't know about
519 $self->_check_metaclass_compatibility();
520 $self->_superclasses_updated();
522 @{$self->get_package_symbol($var_spec)};
525 sub _superclasses_updated {
527 $self->update_meta_instance_dependencies();
532 my $super_class = $self->name;
534 return @{ $super_class->mro::get_isarev() };
537 sub direct_subclasses {
539 my $super_class = $self->name;
544 } Class::MOP::Class->initialize($_)->superclasses
549 return @{ mro::get_linear_isa( (shift)->name ) };
552 sub class_precedence_list {
554 my $name = $self->name;
556 unless (Class::MOP::IS_RUNNING_ON_5_10()) {
558 # We need to check for circular inheritance here
559 # if we are are not on 5.10, cause 5.8 detects it
560 # late. This will do nothing if all is well, and
561 # blow up otherwise. Yes, it's an ugly hack, better
562 # suggestions are welcome.
564 ($name || return)->isa('This is a test for circular inheritance')
567 # if our mro is c3, we can
568 # just grab the linear_isa
569 if (mro::get_mro($name) eq 'c3') {
570 return @{ mro::get_linear_isa($name) }
574 # we can't grab the linear_isa for dfs
575 # since it has all the duplicates
580 $self->initialize($_)->class_precedence_list()
581 } $self->superclasses()
588 sub wrap_method_body {
589 my ( $self, %args ) = @_;
591 ('CODE' eq ref $args{body})
592 || confess "Your code block must be a CODE reference";
594 $self->method_metaclass->wrap(
595 package_name => $self->name,
601 my ($self, $method_name, $method) = @_;
602 (defined $method_name && $method_name)
603 || confess "You must define a method name";
606 if (blessed($method)) {
607 $body = $method->body;
608 if ($method->package_name ne $self->name) {
609 $method = $method->clone(
610 package_name => $self->name,
612 ) if $method->can('clone');
617 $method = $self->wrap_method_body( body => $body, name => $method_name );
620 $method->attach_to_class($self);
622 # This used to call get_method_map, which meant we would build all
623 # the method objects for the class just because we added one
624 # method. This is hackier, but quicker too.
625 $self->{methods}{$method_name} = $method;
627 my ( $current_package, $current_name ) = Class::MOP::get_code_info($body);
629 if ( $current_name eq '__ANON__' ) {
630 my $full_method_name = ($self->name . '::' . $method_name);
631 subname($full_method_name => $body);
634 $self->add_package_symbol(
635 { sigil => '&', type => 'CODE', name => $method_name },
641 my $fetch_and_prepare_method = sub {
642 my ($self, $method_name) = @_;
643 my $wrapped_metaclass = $self->wrapped_method_metaclass;
645 my $method = $self->get_method($method_name);
646 # if we dont have local ...
648 # try to find the next method
649 $method = $self->find_next_method_by_name($method_name);
650 # die if it does not exist
652 || confess "The method '$method_name' was not found in the inheritance hierarchy for " . $self->name;
653 # and now make sure to wrap it
654 # even if it is already wrapped
655 # because we need a new sub ref
656 $method = $wrapped_metaclass->wrap($method);
659 # now make sure we wrap it properly
660 $method = $wrapped_metaclass->wrap($method)
661 unless $method->isa($wrapped_metaclass);
663 $self->add_method($method_name => $method);
667 sub add_before_method_modifier {
668 my ($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_before_modifier(
673 subname(':before' => $method_modifier)
677 sub add_after_method_modifier {
678 my ($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_after_modifier(
683 subname(':after' => $method_modifier)
687 sub add_around_method_modifier {
688 my ($self, $method_name, $method_modifier) = @_;
689 (defined $method_name && $method_name)
690 || confess "You must pass in a method name";
691 my $method = $fetch_and_prepare_method->($self, $method_name);
692 $method->add_around_modifier(
693 subname(':around' => $method_modifier)
698 # the methods above used to be named like this:
699 # ${pkg}::${method}:(before|after|around)
700 # but this proved problematic when using one modifier
701 # to wrap multiple methods (something which is likely
702 # to happen pretty regularly IMO). So instead of naming
703 # it like this, I have chosen to just name them purely
704 # with their modifier names, like so:
705 # :(before|after|around)
706 # The fact is that in a stack trace, it will be fairly
707 # evident from the context what method they are attached
708 # to, and so don't need the fully qualified name.
712 Carp::cluck("The alias_method method is deprecated. Use add_method instead.\n");
714 shift->add_method(@_);
718 my ($self, $method_name) = @_;
719 (defined $method_name && $method_name)
720 || confess "You must define a method name";
722 exists $self->{methods}{$method_name} || exists $self->get_method_map->{$method_name};
726 my ($self, $method_name) = @_;
727 (defined $method_name && $method_name)
728 || confess "You must define a method name";
730 return $self->{methods}{$method_name} || $self->get_method_map->{$method_name};
734 my ($self, $method_name) = @_;
735 (defined $method_name && $method_name)
736 || confess "You must define a method name";
738 my $removed_method = delete $self->get_method_map->{$method_name};
740 $self->remove_package_symbol(
741 { sigil => '&', type => 'CODE', name => $method_name }
744 $removed_method->detach_from_class if $removed_method;
746 $self->update_package_cache_flag; # still valid, since we just removed the method from the map
748 return $removed_method;
751 sub get_method_list {
753 keys %{$self->get_method_map};
756 sub find_method_by_name {
757 my ($self, $method_name) = @_;
758 (defined $method_name && $method_name)
759 || confess "You must define a method name to find";
760 foreach my $class ($self->linearized_isa) {
761 # fetch the meta-class ...
762 my $meta = $self->initialize($class);
763 return $meta->get_method($method_name)
764 if $meta->has_method($method_name);
769 sub get_all_methods {
771 my %methods = map { %{ $self->initialize($_)->get_method_map } } reverse $self->linearized_isa;
772 return values %methods;
775 sub compute_all_applicable_methods {
776 Carp::cluck('The compute_all_applicable_methods method is deprecated.'
777 . " Use get_all_methods instead.\n");
782 class => $_->package_name,
783 code => $_, # sigh, overloading
785 } shift->get_all_methods(@_);
788 sub get_all_method_names {
791 grep { $uniq{$_}++ == 0 } map { $_->name } $self->get_all_methods;
794 sub find_all_methods_by_name {
795 my ($self, $method_name) = @_;
796 (defined $method_name && $method_name)
797 || confess "You must define a method name to find";
799 foreach my $class ($self->linearized_isa) {
800 # fetch the meta-class ...
801 my $meta = $self->initialize($class);
803 name => $method_name,
805 code => $meta->get_method($method_name)
806 } if $meta->has_method($method_name);
811 sub find_next_method_by_name {
812 my ($self, $method_name) = @_;
813 (defined $method_name && $method_name)
814 || confess "You must define a method name to find";
815 my @cpl = $self->linearized_isa;
816 shift @cpl; # discard ourselves
817 foreach my $class (@cpl) {
818 # fetch the meta-class ...
819 my $meta = $self->initialize($class);
820 return $meta->get_method($method_name)
821 if $meta->has_method($method_name);
830 # either we have an attribute object already
831 # or we need to create one from the args provided
832 my $attribute = blessed($_[0]) ? $_[0] : $self->attribute_metaclass->new(@_);
833 # make sure it is derived from the correct type though
834 ($attribute->isa('Class::MOP::Attribute'))
835 || confess "Your attribute must be an instance of Class::MOP::Attribute (or a subclass)";
837 # first we attach our new attribute
838 # because it might need certain information
839 # about the class which it is attached to
840 $attribute->attach_to_class($self);
842 # then we remove attributes of a conflicting
843 # name here so that we can properly detach
844 # the old attr object, and remove any
845 # accessors it would have generated
846 if ( $self->has_attribute($attribute->name) ) {
847 $self->remove_attribute($attribute->name);
849 $self->invalidate_meta_instances();
852 # get our count of previously inserted attributes and
853 # increment by one so this attribute knows its order
854 my $order = (scalar keys %{$self->get_attribute_map}) - 1;
855 $attribute->_set_insertion_order($order + 1);
857 # then onto installing the new accessors
858 $self->get_attribute_map->{$attribute->name} = $attribute;
860 # invalidate package flag here
861 my $e = do { local $@; eval { $attribute->install_accessors() }; $@ };
863 $self->remove_attribute($attribute->name);
870 sub update_meta_instance_dependencies {
873 if ( $self->{meta_instance_dependencies} ) {
874 return $self->add_meta_instance_dependencies;
878 sub add_meta_instance_dependencies {
881 $self->remove_meta_instance_dependencies;
883 my @attrs = $self->get_all_attributes();
886 my @classes = grep { not $seen{$_->name}++ } map { $_->associated_class } @attrs;
888 foreach my $class ( @classes ) {
889 $class->add_dependent_meta_instance($self);
892 $self->{meta_instance_dependencies} = \@classes;
895 sub remove_meta_instance_dependencies {
898 if ( my $classes = delete $self->{meta_instance_dependencies} ) {
899 foreach my $class ( @$classes ) {
900 $class->remove_dependent_meta_instance($self);
910 sub add_dependent_meta_instance {
911 my ( $self, $metaclass ) = @_;
912 push @{ $self->{dependent_meta_instances} }, $metaclass;
915 sub remove_dependent_meta_instance {
916 my ( $self, $metaclass ) = @_;
917 my $name = $metaclass->name;
918 @$_ = grep { $_->name ne $name } @$_ for $self->{dependent_meta_instances};
921 sub invalidate_meta_instances {
923 $_->invalidate_meta_instance() for $self, @{ $self->{dependent_meta_instances} };
926 sub invalidate_meta_instance {
928 undef $self->{_meta_instance};
932 my ($self, $attribute_name) = @_;
933 (defined $attribute_name && $attribute_name)
934 || confess "You must define an attribute name";
935 exists $self->get_attribute_map->{$attribute_name};
939 my ($self, $attribute_name) = @_;
940 (defined $attribute_name && $attribute_name)
941 || confess "You must define an attribute name";
942 return $self->get_attribute_map->{$attribute_name}
944 # this will return undef anyway, so no need ...
945 # if $self->has_attribute($attribute_name);
949 sub remove_attribute {
950 my ($self, $attribute_name) = @_;
951 (defined $attribute_name && $attribute_name)
952 || confess "You must define an attribute name";
953 my $removed_attribute = $self->get_attribute_map->{$attribute_name};
954 return unless defined $removed_attribute;
955 delete $self->get_attribute_map->{$attribute_name};
956 $self->invalidate_meta_instances();
957 $removed_attribute->remove_accessors();
958 $removed_attribute->detach_from_class();
959 return $removed_attribute;
962 sub get_attribute_list {
964 keys %{$self->get_attribute_map};
967 sub get_all_attributes {
969 my %attrs = map { %{ $self->initialize($_)->get_attribute_map } } reverse $self->linearized_isa;
970 return values %attrs;
973 sub compute_all_applicable_attributes {
974 Carp::cluck('The compute_all_applicable_attributes method has been deprecated.'
975 . " Use get_all_attributes instead.\n");
977 shift->get_all_attributes(@_);
980 sub find_attribute_by_name {
981 my ($self, $attr_name) = @_;
982 foreach my $class ($self->linearized_isa) {
983 # fetch the meta-class ...
984 my $meta = $self->initialize($class);
985 return $meta->get_attribute($attr_name)
986 if $meta->has_attribute($attr_name);
991 # check if we can reinitialize
995 # if any local attr is defined
996 return if $self->get_attribute_list;
998 # or any non-declared methods
999 if ( my @methods = values %{ $self->get_method_map } ) {
1000 my $metaclass = $self->method_metaclass;
1001 foreach my $method ( @methods ) {
1002 return if $method->isa("Class::MOP::Method::Generated");
1003 # FIXME do we need to enforce this too? return unless $method->isa($metaclass);
1012 sub is_mutable { 1 }
1013 sub is_immutable { 0 }
1014 sub immutable_transformer { return }
1016 sub _immutable_options {
1017 my ( $self, @args ) = @_;
1020 inline_accessors => 1,
1021 inline_constructor => 1,
1022 inline_destructor => 0,
1024 immutable_trait => $self->immutable_trait,
1025 constructor_name => $self->constructor_name,
1026 constructor_class => $self->constructor_class,
1027 destructor_class => $self->destructor_class,
1032 sub make_immutable {
1033 my ( $self, @args ) = @_;
1035 if ( $self->is_mutable ) {
1036 $self->_initialize_immutable( $self->_immutable_options(@args) );
1037 $self->_rebless_as_immutable(@args);
1048 if ( $self->is_immutable ) {
1049 my @args = $self->immutable_options;
1050 $self->_rebless_as_mutable();
1051 $self->_remove_inlined_code(@args);
1052 delete $self->{__immutable};
1060 sub _rebless_as_immutable {
1061 my ( $self, @args ) = @_;
1063 $self->{__immutable}{original_class} = ref $self;
1065 bless $self => $self->_immutable_metaclass(@args);
1068 sub _immutable_metaclass {
1069 my ( $self, %args ) = @_;
1071 if ( my $class = $args{immutable_metaclass} ) {
1075 my $trait = $args{immutable_trait} = $self->immutable_trait
1076 || confess "no immutable trait specified for $self";
1078 my $meta_attr = $self->meta->find_attribute_by_name("immutable_trait");
1082 if ( $meta_attr and $trait eq $meta_attr->default ) {
1084 # if the trait is the same as the default we try and pick a predictable
1085 # name for the immutable metaclass
1086 $class_name = "Class::MOP::Class::Immutable::" . ref($self);
1090 = join( "::", "Class::MOP::Class::Immutable::CustomTrait", $trait,
1091 "ForMetaClass", ref($self) );
1094 if ( Class::MOP::is_class_loaded($class_name) ) {
1095 if ( $class_name->isa($trait) ) {
1100 "$class_name is already defined but does not inherit $trait";
1104 my @super = ( $trait, ref($self) );
1106 my $meta = Class::MOP::Class->initialize($class_name);
1107 $meta->superclasses(@super);
1109 $meta->make_immutable;
1115 sub _remove_inlined_code {
1118 $self->remove_method( $_->name ) for $self->_inlined_methods;
1120 delete $self->{__immutable}{inlined_methods};
1123 sub _inlined_methods { @{ $_[0]{__immutable}{inlined_methods} || [] } }
1125 sub _add_inlined_method {
1126 my ( $self, $method ) = @_;
1128 push @{ $self->{__immutable}{inlined_methods} ||= [] }, $method;
1131 sub _initialize_immutable {
1132 my ( $self, %args ) = @_;
1134 $self->{__immutable}{options} = \%args;
1135 $self->_install_inlined_code(%args);
1138 sub _install_inlined_code {
1139 my ( $self, %args ) = @_;
1142 $self->_inline_accessors(%args) if $args{inline_accessors};
1143 $self->_inline_constructor(%args) if $args{inline_constructor};
1144 $self->_inline_destructor(%args) if $args{inline_destructor};
1147 sub _rebless_as_mutable {
1150 bless $self, $self->get_mutable_metaclass_name;
1155 sub _inline_accessors {
1158 foreach my $attr_name ( $self->get_attribute_list ) {
1159 $self->get_attribute($attr_name)->install_accessors(1);
1163 sub _inline_constructor {
1164 my ( $self, %args ) = @_;
1166 my $name = $args{constructor_name};
1168 #if ( my $existing = $self->name->can($args{constructor_name}) ) {
1169 # if ( refaddr($existing) == refaddr(\&Moose::Object::new) ) {
1171 unless ( $args{replace_constructor}
1172 or !$self->has_method($name) ) {
1173 my $class = $self->name;
1174 warn "Not inlining a constructor for $class since it defines"
1175 . " its own constructor.\n"
1176 . "If you are certain you don't need to inline your"
1177 . " constructor, specify inline_constructor => 0 in your"
1178 . " call to $class->meta->make_immutable\n";
1182 my $constructor_class = $args{constructor_class};
1184 Class::MOP::load_class($constructor_class);
1186 my $constructor = $constructor_class->new(
1190 package_name => $self->name,
1194 if ( $args{replace_constructor} or $constructor->can_be_inlined ) {
1195 $self->add_method( $name => $constructor );
1196 $self->_add_inlined_method($constructor);
1200 sub _inline_destructor {
1201 my ( $self, %args ) = @_;
1203 ( exists $args{destructor_class} )
1204 || confess "The 'inline_destructor' option is present, but "
1205 . "no destructor class was specified";
1207 if ($self->has_method('DESTROY') ) {
1208 my $class = $self->name;
1209 warn "Not inlining a destructor for $class since it defines"
1210 . " its own destructor.\n";
1214 my $destructor_class = $args{destructor_class};
1216 Class::MOP::load_class($destructor_class);
1218 return unless $destructor_class->is_needed($self);
1220 my $destructor = $destructor_class->new(
1223 package_name => $self->name,
1227 $self->add_method( 'DESTROY' => $destructor );
1229 $self->_add_inlined_method($destructor);
1240 Class::MOP::Class - Class Meta Object
1244 # assuming that class Foo
1245 # has been defined, you can
1247 # use this for introspection ...
1249 # add a method to Foo ...
1250 Foo->meta->add_method( 'bar' => sub {...} )
1252 # get a list of all the classes searched
1253 # the method dispatcher in the correct order
1254 Foo->meta->class_precedence_list()
1256 # remove a method from Foo
1257 Foo->meta->remove_method('bar');
1259 # or use this to actually create classes ...
1261 Class::MOP::Class->create(
1264 superclasses => ['Foo'],
1266 Class::MOP::Attribute->new('$bar'),
1267 Class::MOP::Attribute->new('$baz'),
1270 calculate_bar => sub {...},
1271 construct_baz => sub {...}
1278 The Class Protocol is the largest and most complex part of the
1279 Class::MOP meta-object protocol. It controls the introspection and
1280 manipulation of Perl 5 classes, and it can create them as well. The
1281 best way to understand what this module can do, is to read the
1282 documentation for each of its methods.
1286 C<Class::MOP::Class> is a subclass of L<Class::MOP::Module>.
1290 =head2 Class construction
1292 These methods all create new C<Class::MOP::Class> objects. These
1293 objects can represent existing classes, or they can be used to create
1294 new classes from scratch.
1296 The metaclass object for a given class is a singleton. If you attempt
1297 to create a metaclass for the same class twice, you will just get the
1302 =item B<< Class::MOP::Class->create($package_name, %options) >>
1304 This method creates a new C<Class::MOP::Class> object with the given
1305 package name. It accepts a number of options.
1311 An optional version number for the newly created package.
1315 An optional authority for the newly created package.
1317 =item * superclasses
1319 An optional array reference of superclass names.
1323 An optional hash reference of methods for the class. The keys of the
1324 hash reference are method names, and values are subroutine references.
1328 An optional array reference of attributes.
1330 An attribute can be passed as an existing L<Class::MOP::Attribute>
1331 object, I<or> or as a hash reference of options which will be passed
1332 to the attribute metaclass's constructor.
1336 =item B<< Class::MOP::Class->create_anon_class(%options) >>
1338 This method works just like C<< Class::MOP::Class->create >> but it
1339 creates an "anonymous" class. In fact, the class does have a name, but
1340 that name is a unique name generated internally by this module.
1342 It accepts the same C<superclasses>, C<methods>, and C<attributes>
1343 parameters that C<create> accepts.
1345 Anonymous classes are destroyed once the metaclass they are attached
1346 to goes out of scope, and will be removed from Perl's internal symbol
1349 All instances of an anonymous class keep a special reference to the
1350 metaclass object, which prevents the metaclass from going out of scope
1351 while any instances exist.
1353 This only works if the instance if based on a hash reference, however.
1355 =item B<< Class::MOP::Class->initialize($package_name, %options) >>
1357 This method will initialize a C<Class::MOP::Class> object for the
1358 named package. Unlike C<create>, this method I<will not> create a new
1361 The purpose of this method is to retrieve a C<Class::MOP::Class>
1362 object for introspecting an existing class.
1364 If an existing C<Class::MOP::Class> object exists for the named
1365 package, it will be returned, and any options provided will be
1368 If the object does not yet exist, it will be created.
1370 The valid options that can be passed to this method are
1371 C<attribute_metaclass>, C<method_metaclass>,
1372 C<wrapped_method_metaclass>, and C<instance_metaclass>. These are all
1373 optional, and default to the appropriate class in the C<Class::MOP>
1378 =head2 Object instance construction and cloning
1380 These methods are all related to creating and/or cloning object
1385 =item B<< $metaclass->clone_object($instance, %params) >>
1387 This method clones an existing object instance. Any parameters you
1388 provide are will override existing attribute values in the object.
1390 This is a convenience method for cloning an object instance, then
1391 blessing it into the appropriate package.
1393 You could implement a clone method in your class, using this method:
1396 my ($self, %params) = @_;
1397 $self->meta->clone_object($self, %params);
1400 =item B<< $metaclass->rebless_instance($instance, %params) >>
1402 This method changes the class of C<$instance> to the metaclass's class.
1404 You can only rebless an instance into a subclass of its current
1405 class. If you pass any additional parameters, these will be treated
1406 like constructor parameters and used to initialize the object's
1407 attributes. Any existing attributes that are already set will be
1410 Before reblessing the instance, this method will call
1411 C<rebless_instance_away> on the instance's current metaclass. This method
1412 will be passed the instance, the new metaclass, and any parameters
1413 specified to C<rebless_instance>. By default, C<rebless_instance_away>
1414 does nothing; it is merely a hook.
1416 =item B<< $metaclass->new_object(%params) >>
1418 This method is used to create a new object of the metaclass's
1419 class. Any parameters you provide are used to initialize the
1420 instance's attributes.
1422 =item B<< $metaclass->instance_metaclass >>
1424 Returns the class name of the instance metaclass, see
1425 L<Class::MOP::Instance> for more information on the instance
1428 =item B<< $metaclass->get_meta_instance >>
1430 Returns an instance of the C<instance_metaclass> to be used in the
1431 construction of a new instance of the class.
1435 =head2 Informational predicates
1437 These are a few predicate methods for asking information about the
1442 =item B<< $metaclass->is_anon_class >>
1444 This returns true if the class was created by calling C<<
1445 Class::MOP::Class->create_anon_class >>.
1447 =item B<< $metaclass->is_mutable >>
1449 This returns true if the class is still mutable.
1451 =item B<< $metaclass->is_immutable >>
1453 This returns true if the class has been made immutable.
1455 =item B<< $metaclass->is_pristine >>
1457 A class is I<not> pristine if it has non-inherited attributes or if it
1458 has any generated methods.
1462 =head2 Inheritance Relationships
1466 =item B<< $metaclass->superclasses(@superclasses) >>
1468 This is a read-write accessor which represents the superclass
1469 relationships of the metaclass's class.
1471 This is basically sugar around getting and setting C<@ISA>.
1473 =item B<< $metaclass->class_precedence_list >>
1475 This returns a list of all of the class's ancestor classes. The
1476 classes are returned in method dispatch order.
1478 =item B<< $metaclass->linearized_isa >>
1480 This returns a list based on C<class_precedence_list> but with all
1483 =item B<< $metaclass->subclasses >>
1485 This returns a list of all subclasses for this class, even indirect
1488 =item B<< $metaclass->direct_subclasses >>
1490 This returns a list of immediate subclasses for this class, which does not
1491 include indirect subclasses.
1495 =head2 Method introspection and creation
1497 These methods allow you to introspect a class's methods, as well as
1498 add, remove, or change methods.
1500 Determining what is truly a method in a Perl 5 class requires some
1501 heuristics (aka guessing).
1503 Methods defined outside the package with a fully qualified name (C<sub
1504 Package::name { ... }>) will be included. Similarly, methods named
1505 with a fully qualified name using L<Sub::Name> are also included.
1507 However, we attempt to ignore imported functions.
1509 Ultimately, we are using heuristics to determine what truly is a
1510 method in a class, and these heuristics may get the wrong answer in
1511 some edge cases. However, for most "normal" cases the heuristics work
1516 =item B<< $metaclass->get_method($method_name) >>
1518 This will return a L<Class::MOP::Method> for the specified
1519 C<$method_name>. If the class does not have the specified method, it
1522 =item B<< $metaclass->has_method($method_name) >>
1524 Returns a boolean indicating whether or not the class defines the
1525 named method. It does not include methods inherited from parent
1528 =item B<< $metaclass->get_method_map >>
1530 Returns a hash reference representing the methods defined in this
1531 class. The keys are method names and the values are
1532 L<Class::MOP::Method> objects.
1534 =item B<< $metaclass->get_method_list >>
1536 This will return a list of method I<names> for all methods defined in
1539 =item B<< $metaclass->get_all_methods >>
1541 This will traverse the inheritance hierarchy and return a list of all
1542 the L<Class::MOP::Method> objects for this class and its parents.
1544 =item B<< $metaclass->find_method_by_name($method_name) >>
1546 This will return a L<Class::MOP::Method> for the specified
1547 C<$method_name>. If the class does not have the specified method, it
1550 Unlike C<get_method>, this method I<will> look for the named method in
1553 =item B<< $metaclass->get_all_method_names >>
1555 This will return a list of method I<names> for all of this class's
1556 methods, including inherited methods.
1558 =item B<< $metaclass->find_all_methods_by_name($method_name) >>
1560 This method looks for the named method in the class and all of its
1561 parents. It returns every matching method it finds in the inheritance
1562 tree, so it returns a list of methods.
1564 Each method is returned as a hash reference with three keys. The keys
1565 are C<name>, C<class>, and C<code>. The C<code> key has a
1566 L<Class::MOP::Method> object as its value.
1568 The list of methods is distinct.
1570 =item B<< $metaclass->find_next_method_by_name($method_name) >>
1572 This method returns the first method in any superclass matching the
1573 given name. It is effectively the method that C<SUPER::$method_name>
1576 =item B<< $metaclass->add_method($method_name, $method) >>
1578 This method takes a method name and a subroutine reference, and adds
1579 the method to the class.
1581 The subroutine reference can be a L<Class::MOP::Method>, and you are
1582 strongly encouraged to pass a meta method object instead of a code
1583 reference. If you do so, that object gets stored as part of the
1584 class's method map directly. If not, the meta information will have to
1585 be recreated later, and may be incorrect.
1587 If you provide a method object, this method will clone that object if
1588 the object's package name does not match the class name. This lets us
1589 track the original source of any methods added from other classes
1590 (notably Moose roles).
1592 =item B<< $metaclass->remove_method($method_name) >>
1594 Remove the named method from the class. This method returns the
1595 L<Class::MOP::Method> object for the method.
1597 =item B<< $metaclass->method_metaclass >>
1599 Returns the class name of the method metaclass, see
1600 L<Class::MOP::Method> for more information on the method metaclass.
1602 =item B<< $metaclass->wrapped_method_metaclass >>
1604 Returns the class name of the wrapped method metaclass, see
1605 L<Class::MOP::Method::Wrapped> for more information on the wrapped
1610 =head2 Attribute introspection and creation
1612 Because Perl 5 does not have a core concept of attributes in classes,
1613 we can only return information about attributes which have been added
1614 via this class's methods. We cannot discover information about
1615 attributes which are defined in terms of "regular" Perl 5 methods.
1619 =item B<< $metaclass->get_attribute($attribute_name) >>
1621 This will return a L<Class::MOP::Attribute> for the specified
1622 C<$attribute_name>. If the class does not have the specified
1623 attribute, it returns C<undef>.
1625 NOTE that get_attribute does not search superclasses, for
1626 that you need to use C<find_attribute_by_name>.
1628 =item B<< $metaclass->has_attribute($attribute_name) >>
1630 Returns a boolean indicating whether or not the class defines the
1631 named attribute. It does not include attributes inherited from parent
1634 =item B<< $metaclass->get_attribute_map >>
1636 Returns a hash reference representing the attributes defined in this
1637 class. The keys are attribute names and the values are
1638 L<Class::MOP::Attribute> objects.
1640 =item B<< $metaclass->get_attribute_list >>
1642 This will return a list of attributes I<names> for all attributes
1643 defined in this class.
1645 =item B<< $metaclass->get_all_attributes >>
1647 This will traverse the inheritance hierarchy and return a list of all
1648 the L<Class::MOP::Attribute> objects for this class and its parents.
1650 =item B<< $metaclass->find_attribute_by_name($attribute_name) >>
1652 This will return a L<Class::MOP::Attribute> for the specified
1653 C<$attribute_name>. If the class does not have the specified
1654 attribute, it returns C<undef>
1656 Unlike C<get_attribute>, this attribute I<will> look for the named
1657 attribute in superclasses.
1659 =item B<< $metaclass->add_attribute(...) >>
1661 This method accepts either an existing L<Class::MOP::Attribute>
1662 object, or parameters suitable for passing to that class's C<new>
1665 The attribute provided will be added to the class.
1667 Any accessor methods defined by the attribute will be added to the
1668 class when the attribute is added.
1670 If an attribute of the same name already exists, the old attribute
1671 will be removed first.
1673 =item B<< $metaclass->remove_attribute($attribute_name) >>
1675 This will remove the named attribute from the class, and
1676 L<Class::MOP::Attribute> object.
1678 Removing an attribute also removes any accessor methods defined by the
1681 However, note that removing an attribute will only affect I<future>
1682 object instances created for this class, not existing instances.
1684 =item B<< $metaclass->attribute_metaclass >>
1686 Returns the class name of the attribute metaclass for this class. By
1687 default, this is L<Class::MOP::Attribute>. for more information on
1691 =head2 Class Immutability
1693 Making a class immutable "freezes" the class definition. You can no
1694 longer call methods which alter the class, such as adding or removing
1695 methods or attributes.
1697 Making a class immutable lets us optimize the class by inlining some
1698 methods, and also allows us to optimize some methods on the metaclass
1701 The immutabilization system in L<Moose> takes much greater advantage
1702 of the inlining features than Class::MOP itself does.
1706 =item B<< $metaclass->make_immutable(%options) >>
1708 This method will create an immutable transformer and uses it to make
1709 the class and its metaclass object immutable.
1711 Details of how immutabilization works are in L<Class::MOP::Immutable>
1714 =item B<< $metaclass->make_mutable >>
1716 Calling this method reverse the immutabilization transformation.
1718 =item B<< $metaclass->immutable_transformer >>
1720 If the class has been made immutable previously, this returns the
1721 L<Class::MOP::Immutable> object that was created to do the
1724 If the class was never made immutable, this method will die.
1728 =head2 Method Modifiers
1730 Method modifiers are hooks which allow a method to be wrapped with
1731 I<before>, I<after> and I<around> method modifiers. Every time a
1732 method is called, it's modifiers are also called.
1734 A class can modify its own methods, as well as methods defined in
1737 =head3 How method modifiers work?
1739 Method modifiers work by wrapping the original method and then
1740 replacing it in the class's symbol table. The wrappers will handle
1741 calling all the modifiers in the appropriate order and preserving the
1742 calling context for the original method.
1744 The return values of C<before> and C<after> modifiers are
1745 ignored. This is because their purpose is B<not> to filter the input
1746 and output of the primary method (this is done with an I<around>
1749 This may seem like an odd restriction to some, but doing this allows
1750 for simple code to be added at the beginning or end of a method call
1751 without altering the function of the wrapped method or placing any
1752 extra responsibility on the code of the modifier.
1754 Of course if you have more complex needs, you can use the C<around>
1755 modifier which allows you to change both the parameters passed to the
1756 wrapped method, as well as its return value.
1758 Before and around modifiers are called in last-defined-first-called
1759 order, while after modifiers are called in first-defined-first-called
1760 order. So the call tree might looks something like this:
1772 =head3 What is the performance impact?
1774 Of course there is a performance cost associated with method
1775 modifiers, but we have made every effort to make that cost directly
1776 proportional to the number of modifier features you utilize.
1778 The wrapping method does it's best to B<only> do as much work as it
1779 absolutely needs to. In order to do this we have moved some of the
1780 performance costs to set-up time, where they are easier to amortize.
1782 All this said, our benchmarks have indicated the following:
1784 simple wrapper with no modifiers 100% slower
1785 simple wrapper with simple before modifier 400% slower
1786 simple wrapper with simple after modifier 450% slower
1787 simple wrapper with simple around modifier 500-550% slower
1788 simple wrapper with all 3 modifiers 1100% slower
1790 These numbers may seem daunting, but you must remember, every feature
1791 comes with some cost. To put things in perspective, just doing a
1792 simple C<AUTOLOAD> which does nothing but extract the name of the
1793 method called and return it costs about 400% over a normal method
1798 =item B<< $metaclass->add_before_method_modifier($method_name, $code) >>
1800 This wraps the specified method with the supplied subroutine
1801 reference. The modifier will be called as a method itself, and will
1802 receive the same arguments as are passed to the method.
1804 When the modifier exits, the wrapped method will be called.
1806 The return value of the modifier will be ignored.
1808 =item B<< $metaclass->add_after_method_modifier($method_name, $code) >>
1810 This wraps the specified method with the supplied subroutine
1811 reference. The modifier will be called as a method itself, and will
1812 receive the same arguments as are passed to the method.
1814 When the wrapped methods exits, the modifier will be called.
1816 The return value of the modifier will be ignored.
1818 =item B<< $metaclass->add_around_method_modifier($method_name, $code) >>
1820 This wraps the specified method with the supplied subroutine
1823 The first argument passed to the modifier will be a subroutine
1824 reference to the wrapped method. The second argument is the object,
1825 and after that come any arguments passed when the method is called.
1827 The around modifier can choose to call the original method, as well as
1828 what arguments to pass if it does so.
1830 The return value of the modifier is what will be seen by the caller.
1834 =head2 Introspection
1838 =item B<< Class::MOP::Class->meta >>
1840 This will return a L<Class::MOP::Class> instance for this class.
1842 It should also be noted that L<Class::MOP> will actually bootstrap
1843 this module by installing a number of attribute meta-objects into its
1850 Stevan Little E<lt>stevan@iinteractive.comE<gt>
1852 =head1 COPYRIGHT AND LICENSE
1854 Copyright 2006-2009 by Infinity Interactive, Inc.
1856 L<http://www.iinteractive.com>
1858 This library is free software; you can redistribute it and/or modify
1859 it under the same terms as Perl itself.