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 = '0.83';
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 $self->update_meta_instance_dependencies();
522 @{$self->get_package_symbol($var_spec)};
527 my $super_class = $self->name;
529 return @{ $super_class->mro::get_isarev() };
534 return @{ mro::get_linear_isa( (shift)->name ) };
537 sub class_precedence_list {
539 my $name = $self->name;
541 unless (Class::MOP::IS_RUNNING_ON_5_10()) {
543 # We need to check for circular inheritance here
544 # if we are are not on 5.10, cause 5.8 detects it
545 # late. This will do nothing if all is well, and
546 # blow up otherwise. Yes, it's an ugly hack, better
547 # suggestions are welcome.
549 ($name || return)->isa('This is a test for circular inheritance')
552 # if our mro is c3, we can
553 # just grab the linear_isa
554 if (mro::get_mro($name) eq 'c3') {
555 return @{ mro::get_linear_isa($name) }
559 # we can't grab the linear_isa for dfs
560 # since it has all the duplicates
565 $self->initialize($_)->class_precedence_list()
566 } $self->superclasses()
573 sub wrap_method_body {
574 my ( $self, %args ) = @_;
576 ('CODE' eq ref $args{body})
577 || confess "Your code block must be a CODE reference";
579 $self->method_metaclass->wrap(
580 package_name => $self->name,
586 my ($self, $method_name, $method) = @_;
587 (defined $method_name && $method_name)
588 || confess "You must define a method name";
591 if (blessed($method)) {
592 $body = $method->body;
593 if ($method->package_name ne $self->name) {
594 $method = $method->clone(
595 package_name => $self->name,
597 ) if $method->can('clone');
602 $method = $self->wrap_method_body( body => $body, name => $method_name );
605 $method->attach_to_class($self);
607 # This used to call get_method_map, which meant we would build all
608 # the method objects for the class just because we added one
609 # method. This is hackier, but quicker too.
610 $self->{methods}{$method_name} = $method;
612 my $full_method_name = ($self->name . '::' . $method_name);
613 $self->add_package_symbol(
614 { sigil => '&', type => 'CODE', name => $method_name },
615 subname($full_method_name => $body)
620 my $fetch_and_prepare_method = sub {
621 my ($self, $method_name) = @_;
622 my $wrapped_metaclass = $self->wrapped_method_metaclass;
624 my $method = $self->get_method($method_name);
625 # if we dont have local ...
627 # try to find the next method
628 $method = $self->find_next_method_by_name($method_name);
629 # die if it does not exist
631 || confess "The method '$method_name' was not found in the inheritance hierarchy for " . $self->name;
632 # and now make sure to wrap it
633 # even if it is already wrapped
634 # because we need a new sub ref
635 $method = $wrapped_metaclass->wrap($method);
638 # now make sure we wrap it properly
639 $method = $wrapped_metaclass->wrap($method)
640 unless $method->isa($wrapped_metaclass);
642 $self->add_method($method_name => $method);
646 sub add_before_method_modifier {
647 my ($self, $method_name, $method_modifier) = @_;
648 (defined $method_name && $method_name)
649 || confess "You must pass in a method name";
650 my $method = $fetch_and_prepare_method->($self, $method_name);
651 $method->add_before_modifier(
652 subname(':before' => $method_modifier)
656 sub add_after_method_modifier {
657 my ($self, $method_name, $method_modifier) = @_;
658 (defined $method_name && $method_name)
659 || confess "You must pass in a method name";
660 my $method = $fetch_and_prepare_method->($self, $method_name);
661 $method->add_after_modifier(
662 subname(':after' => $method_modifier)
666 sub add_around_method_modifier {
667 my ($self, $method_name, $method_modifier) = @_;
668 (defined $method_name && $method_name)
669 || confess "You must pass in a method name";
670 my $method = $fetch_and_prepare_method->($self, $method_name);
671 $method->add_around_modifier(
672 subname(':around' => $method_modifier)
677 # the methods above used to be named like this:
678 # ${pkg}::${method}:(before|after|around)
679 # but this proved problematic when using one modifier
680 # to wrap multiple methods (something which is likely
681 # to happen pretty regularly IMO). So instead of naming
682 # it like this, I have chosen to just name them purely
683 # with their modifier names, like so:
684 # :(before|after|around)
685 # The fact is that in a stack trace, it will be fairly
686 # evident from the context what method they are attached
687 # to, and so don't need the fully qualified name.
691 Carp::cluck("The alias_method method is deprecated. Use add_method instead.\n");
693 shift->add_method(@_);
697 my ($self, $method_name) = @_;
698 (defined $method_name && $method_name)
699 || confess "You must define a method name";
701 exists $self->{methods}{$method_name} || exists $self->get_method_map->{$method_name};
705 my ($self, $method_name) = @_;
706 (defined $method_name && $method_name)
707 || confess "You must define a method name";
709 return $self->{methods}{$method_name} || $self->get_method_map->{$method_name};
713 my ($self, $method_name) = @_;
714 (defined $method_name && $method_name)
715 || confess "You must define a method name";
717 my $removed_method = delete $self->get_method_map->{$method_name};
719 $self->remove_package_symbol(
720 { sigil => '&', type => 'CODE', name => $method_name }
723 $removed_method->detach_from_class if $removed_method;
725 $self->update_package_cache_flag; # still valid, since we just removed the method from the map
727 return $removed_method;
730 sub get_method_list {
732 keys %{$self->get_method_map};
735 sub find_method_by_name {
736 my ($self, $method_name) = @_;
737 (defined $method_name && $method_name)
738 || confess "You must define a method name to find";
739 foreach my $class ($self->linearized_isa) {
740 # fetch the meta-class ...
741 my $meta = $self->initialize($class);
742 return $meta->get_method($method_name)
743 if $meta->has_method($method_name);
748 sub get_all_methods {
750 my %methods = map { %{ $self->initialize($_)->get_method_map } } reverse $self->linearized_isa;
751 return values %methods;
754 sub compute_all_applicable_methods {
755 Carp::cluck('The compute_all_applicable_methods method is deprecated.'
756 . " Use get_all_methods instead.\n");
761 class => $_->package_name,
762 code => $_, # sigh, overloading
764 } shift->get_all_methods(@_);
767 sub get_all_method_names {
770 grep { $uniq{$_}++ == 0 } map { $_->name } $self->get_all_methods;
773 sub find_all_methods_by_name {
774 my ($self, $method_name) = @_;
775 (defined $method_name && $method_name)
776 || confess "You must define a method name to find";
778 foreach my $class ($self->linearized_isa) {
779 # fetch the meta-class ...
780 my $meta = $self->initialize($class);
782 name => $method_name,
784 code => $meta->get_method($method_name)
785 } if $meta->has_method($method_name);
790 sub find_next_method_by_name {
791 my ($self, $method_name) = @_;
792 (defined $method_name && $method_name)
793 || confess "You must define a method name to find";
794 my @cpl = $self->linearized_isa;
795 shift @cpl; # discard ourselves
796 foreach my $class (@cpl) {
797 # fetch the meta-class ...
798 my $meta = $self->initialize($class);
799 return $meta->get_method($method_name)
800 if $meta->has_method($method_name);
809 # either we have an attribute object already
810 # or we need to create one from the args provided
811 my $attribute = blessed($_[0]) ? $_[0] : $self->attribute_metaclass->new(@_);
812 # make sure it is derived from the correct type though
813 ($attribute->isa('Class::MOP::Attribute'))
814 || confess "Your attribute must be an instance of Class::MOP::Attribute (or a subclass)";
816 # first we attach our new attribute
817 # because it might need certain information
818 # about the class which it is attached to
819 $attribute->attach_to_class($self);
821 # then we remove attributes of a conflicting
822 # name here so that we can properly detach
823 # the old attr object, and remove any
824 # accessors it would have generated
825 if ( $self->has_attribute($attribute->name) ) {
826 $self->remove_attribute($attribute->name);
828 $self->invalidate_meta_instances();
831 # then onto installing the new accessors
832 $self->get_attribute_map->{$attribute->name} = $attribute;
834 # invalidate package flag here
835 my $e = do { local $@; eval { $attribute->install_accessors() }; $@ };
837 $self->remove_attribute($attribute->name);
844 sub update_meta_instance_dependencies {
847 if ( $self->{meta_instance_dependencies} ) {
848 return $self->add_meta_instance_dependencies;
852 sub add_meta_instance_dependencies {
855 $self->remove_meta_instance_dependencies;
857 my @attrs = $self->get_all_attributes();
860 my @classes = grep { not $seen{$_->name}++ } map { $_->associated_class } @attrs;
862 foreach my $class ( @classes ) {
863 $class->add_dependent_meta_instance($self);
866 $self->{meta_instance_dependencies} = \@classes;
869 sub remove_meta_instance_dependencies {
872 if ( my $classes = delete $self->{meta_instance_dependencies} ) {
873 foreach my $class ( @$classes ) {
874 $class->remove_dependent_meta_instance($self);
884 sub add_dependent_meta_instance {
885 my ( $self, $metaclass ) = @_;
886 push @{ $self->{dependent_meta_instances} }, $metaclass;
889 sub remove_dependent_meta_instance {
890 my ( $self, $metaclass ) = @_;
891 my $name = $metaclass->name;
892 @$_ = grep { $_->name ne $name } @$_ for $self->{dependent_meta_instances};
895 sub invalidate_meta_instances {
897 $_->invalidate_meta_instance() for $self, @{ $self->{dependent_meta_instances} };
900 sub invalidate_meta_instance {
902 undef $self->{_meta_instance};
906 my ($self, $attribute_name) = @_;
907 (defined $attribute_name && $attribute_name)
908 || confess "You must define an attribute name";
909 exists $self->get_attribute_map->{$attribute_name};
913 my ($self, $attribute_name) = @_;
914 (defined $attribute_name && $attribute_name)
915 || confess "You must define an attribute name";
916 return $self->get_attribute_map->{$attribute_name}
918 # this will return undef anyway, so no need ...
919 # if $self->has_attribute($attribute_name);
923 sub remove_attribute {
924 my ($self, $attribute_name) = @_;
925 (defined $attribute_name && $attribute_name)
926 || confess "You must define an attribute name";
927 my $removed_attribute = $self->get_attribute_map->{$attribute_name};
928 return unless defined $removed_attribute;
929 delete $self->get_attribute_map->{$attribute_name};
930 $self->invalidate_meta_instances();
931 $removed_attribute->remove_accessors();
932 $removed_attribute->detach_from_class();
933 return $removed_attribute;
936 sub get_attribute_list {
938 keys %{$self->get_attribute_map};
941 sub get_all_attributes {
943 my %attrs = map { %{ $self->initialize($_)->get_attribute_map } } reverse $self->linearized_isa;
944 return values %attrs;
947 sub compute_all_applicable_attributes {
948 Carp::cluck('The compute_all_applicable_attributes method has been deprecated.'
949 . " Use get_all_attributes instead.\n");
951 shift->get_all_attributes(@_);
954 sub find_attribute_by_name {
955 my ($self, $attr_name) = @_;
956 foreach my $class ($self->linearized_isa) {
957 # fetch the meta-class ...
958 my $meta = $self->initialize($class);
959 return $meta->get_attribute($attr_name)
960 if $meta->has_attribute($attr_name);
965 # check if we can reinitialize
969 # if any local attr is defined
970 return if $self->get_attribute_list;
972 # or any non-declared methods
973 if ( my @methods = values %{ $self->get_method_map } ) {
974 my $metaclass = $self->method_metaclass;
975 foreach my $method ( @methods ) {
976 return if $method->isa("Class::MOP::Method::Generated");
977 # FIXME do we need to enforce this too? return unless $method->isa($metaclass);
987 sub is_immutable { 0 }
988 sub immutable_transformer { return }
990 sub _immutable_options {
991 my ( $self, @args ) = @_;
994 inline_accessors => 1,
995 inline_constructor => 1,
996 inline_destructor => 0,
998 immutable_trait => $self->immutable_trait,
999 constructor_name => $self->constructor_name,
1000 constructor_class => $self->constructor_class,
1001 destructor_class => $self->destructor_class,
1006 sub make_immutable {
1007 my ( $self, @args ) = @_;
1009 if ( $self->is_mutable ) {
1010 $self->_initialize_immutable( $self->_immutable_options(@args) );
1011 $self->_rebless_as_immutable(@args);
1022 if ( $self->is_immutable ) {
1023 my @args = $self->immutable_options;
1024 $self->_rebless_as_mutable();
1025 $self->_remove_inlined_code(@args);
1026 delete $self->{__immutable};
1034 sub _rebless_as_immutable {
1035 my ( $self, @args ) = @_;
1037 $self->{__immutable}{original_class} = ref $self;
1039 bless $self => $self->_immutable_metaclass(@args);
1042 sub _immutable_metaclass {
1043 my ( $self, %args ) = @_;
1045 if ( my $class = $args{immutable_metaclass} ) {
1049 my $trait = $args{immutable_trait} = $self->immutable_trait
1050 || confess "no immutable trait specified for $self";
1052 my $meta_attr = $self->meta->find_attribute_by_name("immutable_trait");
1056 if ( $meta_attr and $trait eq $meta_attr->default ) {
1058 # if the trait is the same as the default we try and pick a predictable
1059 # name for the immutable metaclass
1060 $class_name = "Class::MOP::Class::Immutable::" . ref($self);
1064 = join( "::", "Class::MOP::Class::Immutable::CustomTrait", $trait,
1065 "ForMetaClass", ref($self) );
1068 if ( Class::MOP::is_class_loaded($class_name) ) {
1069 if ( $class_name->isa($trait) ) {
1074 "$class_name is already defined but does not inherit $trait";
1078 my @super = ( $trait, ref($self) );
1080 my $meta = Class::MOP::Class->initialize($class_name);
1081 $meta->superclasses(@super);
1083 $meta->make_immutable;
1089 sub _remove_inlined_code {
1092 $self->remove_method( $_->name ) for $self->_inlined_methods;
1094 delete $self->{__immutable}{inlined_methods};
1097 sub _inlined_methods { @{ $_[0]{__immutable}{inlined_methods} || [] } }
1099 sub _add_inlined_method {
1100 my ( $self, $method ) = @_;
1102 push @{ $self->{__immutable}{inlined_methods} ||= [] }, $method;
1105 sub _initialize_immutable {
1106 my ( $self, %args ) = @_;
1108 $self->{__immutable}{options} = \%args;
1109 $self->_install_inlined_code(%args);
1112 sub _install_inlined_code {
1113 my ( $self, %args ) = @_;
1116 $self->_inline_accessors(%args) if $args{inline_accessors};
1117 $self->_inline_constructor(%args) if $args{inline_constructor};
1118 $self->_inline_destructor(%args) if $args{inline_destructor};
1121 sub _rebless_as_mutable {
1124 bless $self, $self->get_mutable_metaclass_name;
1129 sub _inline_accessors {
1132 foreach my $attr_name ( $self->get_attribute_list ) {
1133 $self->get_attribute($attr_name)->install_accessors(1);
1137 sub _inline_constructor {
1138 my ( $self, %args ) = @_;
1140 my $name = $args{constructor_name};
1142 #if ( my $existing = $self->name->can($args{constructor_name}) ) {
1143 # if ( refaddr($existing) == refaddr(\&Moose::Object::new) ) {
1145 unless ( $args{replace_constructor}
1146 or !$self->has_method($name) ) {
1147 my $class = $self->name;
1148 warn "Not inlining a constructor for $class since it defines"
1149 . " its own constructor.\n"
1150 . "If you are certain you don't need to inline your"
1151 . " constructor, specify inline_constructor => 0 in your"
1152 . " call to $class->meta->make_immutable\n";
1156 my $constructor_class = $args{constructor_class};
1158 Class::MOP::load_class($constructor_class);
1160 my $constructor = $constructor_class->new(
1164 package_name => $self->name,
1168 if ( $args{replace_constructor} or $constructor->can_be_inlined ) {
1169 $self->add_method( $name => $constructor );
1170 $self->_add_inlined_method($constructor);
1174 sub _inline_destructor {
1175 my ( $self, %args ) = @_;
1177 ( exists $args{destructor_class} )
1178 || confess "The 'inline_destructor' option is present, but "
1179 . "no destructor class was specified";
1181 my $destructor_class = $args{destructor_class};
1183 Class::MOP::load_class($destructor_class);
1185 return unless $destructor_class->is_needed($self);
1187 my $destructor = $destructor_class->new(
1190 package_name => $self->name,
1194 $self->add_method( 'DESTROY' => $destructor );
1196 $self->_add_inlined_method($destructor);
1207 Class::MOP::Class - Class Meta Object
1211 # assuming that class Foo
1212 # has been defined, you can
1214 # use this for introspection ...
1216 # add a method to Foo ...
1217 Foo->meta->add_method( 'bar' => sub {...} )
1219 # get a list of all the classes searched
1220 # the method dispatcher in the correct order
1221 Foo->meta->class_precedence_list()
1223 # remove a method from Foo
1224 Foo->meta->remove_method('bar');
1226 # or use this to actually create classes ...
1228 Class::MOP::Class->create(
1231 superclasses => ['Foo'],
1233 Class::MOP::Attribute->new('$bar'),
1234 Class::MOP::Attribute->new('$baz'),
1237 calculate_bar => sub {...},
1238 construct_baz => sub {...}
1245 The Class Protocol is the largest and most complex part of the
1246 Class::MOP meta-object protocol. It controls the introspection and
1247 manipulation of Perl 5 classes, and it can create them as well. The
1248 best way to understand what this module can do, is to read the
1249 documentation for each of its methods.
1253 C<Class::MOP::Class> is a subclass of L<Class::MOP::Module>.
1257 =head2 Class construction
1259 These methods all create new C<Class::MOP::Class> objects. These
1260 objects can represent existing classes, or they can be used to create
1261 new classes from scratch.
1263 The metaclass object for a given class is a singleton. If you attempt
1264 to create a metaclass for the same class twice, you will just get the
1269 =item B<< Class::MOP::Class->create($package_name, %options) >>
1271 This method creates a new C<Class::MOP::Class> object with the given
1272 package name. It accepts a number of options.
1278 An optional version number for the newly created package.
1282 An optional authority for the newly created package.
1284 =item * superclasses
1286 An optional array reference of superclass names.
1290 An optional hash reference of methods for the class. The keys of the
1291 hash reference are method names, and values are subroutine references.
1295 An optional array reference of attributes.
1297 An attribute can be passed as an existing L<Class::MOP::Attribute>
1298 object, I<or> or as a hash reference of options which will be passed
1299 to the attribute metaclass's constructor.
1303 =item B<< Class::MOP::Class->create_anon_class(%options) >>
1305 This method works just like C<< Class::MOP::Class->create >> but it
1306 creates an "anonymous" class. In fact, the class does have a name, but
1307 that name is a unique name generated internally by this module.
1309 It accepts the same C<superclasses>, C<methods>, and C<attributes>
1310 parameters that C<create> accepts.
1312 Anonymous classes are destroyed once the metaclass they are attached
1313 to goes out of scope, and will be removed from Perl's internal symbol
1316 All instances of an anonymous class keep a special reference to the
1317 metaclass object, which prevents the metaclass from going out of scope
1318 while any instances exist.
1320 This only works if the instance if based on a hash reference, however.
1322 =item B<< Class::MOP::Class->initialize($package_name, %options) >>
1324 This method will initialize a C<Class::MOP::Class> object for the
1325 named package. Unlike C<create>, this method I<will not> create a new
1328 The purpose of this method is to retrieve a C<Class::MOP::Class>
1329 object for introspecting an existing class.
1331 If an existing C<Class::MOP::Class> object exists for the named
1332 package, it will be returned, and any options provided will be
1335 If the object does not yet exist, it will be created.
1337 The valid options that can be passed to this method are
1338 C<attribute_metaclass>, C<method_metaclass>,
1339 C<wrapped_method_metaclass>, and C<instance_metaclass>. These are all
1340 optional, and default to the appropriate class in the C<Class::MOP>
1345 =head2 Object instance construction and cloning
1347 These methods are all related to creating and/or cloning object
1352 =item B<< $metaclass->clone_object($instance, %params) >>
1354 This method clones an existing object instance. Any parameters you
1355 provide are will override existing attribute values in the object.
1357 This is a convenience method for cloning an object instance, then
1358 blessing it into the appropriate package.
1360 You could implement a clone method in your class, using this method:
1363 my ($self, %params) = @_;
1364 $self->meta->clone_object($self, %params);
1367 =item B<< $metaclass->rebless_instance($instance, %params) >>
1369 This method changes the class of C<$instance> to the metaclass's class.
1371 You can only rebless an instance into a subclass of its current
1372 class. If you pass any additional parameters, these will be treated
1373 like constructor parameters and used to initialize the object's
1374 attributes. Any existing attributes that are already set will be
1377 Before reblessing the instance, this method will call
1378 C<rebless_instance_away> on the instance's current metaclass. This method
1379 will be passed the instance, the new metaclass, and any parameters
1380 specified to C<rebless_instance>. By default, C<rebless_instance_away>
1381 does nothing; it is merely a hook.
1383 =item B<< $metaclass->new_object(%params) >>
1385 This method is used to create a new object of the metaclass's
1386 class. Any parameters you provide are used to initialize the
1387 instance's attributes.
1389 =item B<< $metaclass->instance_metaclass >>
1391 Returns the class name of the instance metaclass, see
1392 L<Class::MOP::Instance> for more information on the instance
1395 =item B<< $metaclass->get_meta_instance >>
1397 Returns an instance of the C<instance_metaclass> to be used in the
1398 construction of a new instance of the class.
1402 =head2 Informational predicates
1404 These are a few predicate methods for asking information about the
1409 =item B<< $metaclass->is_anon_class >>
1411 This returns true if the class was created by calling C<<
1412 Class::MOP::Class->create_anon_class >>.
1414 =item B<< $metaclass->is_mutable >>
1416 This returns true if the class is still mutable.
1418 =item B<< $metaclass->is_immutable >>
1420 This returns true if the class has been made immutable.
1422 =item B<< $metaclass->is_pristine >>
1424 A class is I<not> pristine if it has non-inherited attributes or if it
1425 has any generated methods.
1429 =head2 Inheritance Relationships
1433 =item B<< $metaclass->superclasses(@superclasses) >>
1435 This is a read-write accessor which represents the superclass
1436 relationships of the metaclass's class.
1438 This is basically sugar around getting and setting C<@ISA>.
1440 =item B<< $metaclass->class_precedence_list >>
1442 This returns a list of all of the class's ancestor classes. The
1443 classes are returned in method dispatch order.
1445 =item B<< $metaclass->linearized_isa >>
1447 This returns a list based on C<class_precedence_list> but with all
1450 =item B<< $metaclass->subclasses >>
1452 This returns a list of subclasses for this class.
1456 =head2 Method introspection and creation
1458 These methods allow you to introspect a class's methods, as well as
1459 add, remove, or change methods.
1461 Determining what is truly a method in a Perl 5 class requires some
1462 heuristics (aka guessing).
1464 Methods defined outside the package with a fully qualified name (C<sub
1465 Package::name { ... }>) will be included. Similarly, methods named
1466 with a fully qualified name using L<Sub::Name> are also included.
1468 However, we attempt to ignore imported functions.
1470 Ultimately, we are using heuristics to determine what truly is a
1471 method in a class, and these heuristics may get the wrong answer in
1472 some edge cases. However, for most "normal" cases the heuristics work
1477 =item B<< $metaclass->get_method($method_name) >>
1479 This will return a L<Class::MOP::Method> for the specified
1480 C<$method_name>. If the class does not have the specified method, it
1483 =item B<< $metaclass->has_method($method_name) >>
1485 Returns a boolean indicating whether or not the class defines the
1486 named method. It does not include methods inherited from parent
1489 =item B<< $metaclass->get_method_map >>
1491 Returns a hash reference representing the methods defined in this
1492 class. The keys are method names and the values are
1493 L<Class::MOP::Method> objects.
1495 =item B<< $metaclass->get_method_list >>
1497 This will return a list of method I<names> for all methods defined in
1500 =item B<< $metaclass->get_all_methods >>
1502 This will traverse the inheritance hierarchy and return a list of all
1503 the L<Class::MOP::Method> objects for this class and its parents.
1505 =item B<< $metaclass->find_method_by_name($method_name) >>
1507 This will return a L<Class::MOP::Method> for the specified
1508 C<$method_name>. If the class does not have the specified method, it
1511 Unlike C<get_method>, this method I<will> look for the named method in
1514 =item B<< $metaclass->get_all_method_names >>
1516 This will return a list of method I<names> for all of this class's
1517 methods, including inherited methods.
1519 =item B<< $metaclass->find_all_methods_by_name($method_name) >>
1521 This method looks for the named method in the class and all of its
1522 parents. It returns every matching method it finds in the inheritance
1523 tree, so it returns a list of methods.
1525 Each method is returned as a hash reference with three keys. The keys
1526 are C<name>, C<class>, and C<code>. The C<code> key has a
1527 L<Class::MOP::Method> object as its value.
1529 The list of methods is distinct.
1531 =item B<< $metaclass->find_next_method_by_name($method_name) >>
1533 This method returns the first method in any superclass matching the
1534 given name. It is effectively the method that C<SUPER::$method_name>
1537 =item B<< $metaclass->add_method($method_name, $method) >>
1539 This method takes a method name and a subroutine reference, and adds
1540 the method to the class.
1542 The subroutine reference can be a L<Class::MOP::Method>, and you are
1543 strongly encouraged to pass a meta method object instead of a code
1544 reference. If you do so, that object gets stored as part of the
1545 class's method map directly. If not, the meta information will have to
1546 be recreated later, and may be incorrect.
1548 If you provide a method object, this method will clone that object if
1549 the object's package name does not match the class name. This lets us
1550 track the original source of any methods added from other classes
1551 (notably Moose roles).
1553 =item B<< $metaclass->remove_method($method_name) >>
1555 Remove the named method from the class. This method returns the
1556 L<Class::MOP::Method> object for the method.
1558 =item B<< $metaclass->method_metaclass >>
1560 Returns the class name of the method metaclass, see
1561 L<Class::MOP::Method> for more information on the method metaclass.
1563 =item B<< $metaclass->wrapped_method_metaclass >>
1565 Returns the class name of the wrapped method metaclass, see
1566 L<Class::MOP::Method::Wrapped> for more information on the wrapped
1571 =head2 Attribute introspection and creation
1573 Because Perl 5 does not have a core concept of attributes in classes,
1574 we can only return information about attributes which have been added
1575 via this class's methods. We cannot discover information about
1576 attributes which are defined in terms of "regular" Perl 5 methods.
1580 =item B<< $metaclass->get_attribute($attribute_name) >>
1582 This will return a L<Class::MOP::Attribute> for the specified
1583 C<$attribute_name>. If the class does not have the specified
1584 attribute, it returns C<undef>
1586 =item B<< $metaclass->has_attribute($attribute_name) >>
1588 Returns a boolean indicating whether or not the class defines the
1589 named attribute. It does not include attributes inherited from parent
1592 =item B<< $metaclass->get_attribute_map >>
1594 Returns a hash reference representing the attributes defined in this
1595 class. The keys are attribute names and the values are
1596 L<Class::MOP::Attribute> objects.
1598 =item B<< $metaclass->get_attribute_list >>
1600 This will return a list of attributes I<names> for all attributes
1601 defined in this class.
1603 =item B<< $metaclass->get_all_attributes >>
1605 This will traverse the inheritance hierarchy and return a list of all
1606 the L<Class::MOP::Attribute> objects for this class and its parents.
1608 =item B<< $metaclass->find_attribute_by_name($attribute_name) >>
1610 This will return a L<Class::MOP::Attribute> for the specified
1611 C<$attribute_name>. If the class does not have the specified
1612 attribute, it returns C<undef>
1614 Unlike C<get_attribute>, this attribute I<will> look for the named
1615 attribute in superclasses.
1617 =item B<< $metaclass->add_attribute(...) >>
1619 This method accepts either an existing L<Class::MOP::Attribute>
1620 object, or parameters suitable for passing to that class's C<new>
1623 The attribute provided will be added to the class.
1625 Any accessor methods defined by the attribute will be added to the
1626 class when the attribute is added.
1628 If an attribute of the same name already exists, the old attribute
1629 will be removed first.
1631 =item B<< $metaclass->remove_attribute($attribute_name) >>
1633 This will remove the named attribute from the class, and
1634 L<Class::MOP::Attribute> object.
1636 Removing an attribute also removes any accessor methods defined by the
1639 However, note that removing an attribute will only affect I<future>
1640 object instances created for this class, not existing instances.
1642 =item B<< $metaclass->attribute_metaclass >>
1644 Returns the class name of the attribute metaclass for this class. By
1645 default, this is L<Class::MOP::Attribute>. for more information on
1649 =head2 Class Immutability
1651 Making a class immutable "freezes" the class definition. You can no
1652 longer call methods which alter the class, such as adding or removing
1653 methods or attributes.
1655 Making a class immutable lets us optimize the class by inlining some
1656 methods, and also allows us to optimize some methods on the metaclass
1659 The immutabilization system in L<Moose> takes much greater advantage
1660 of the inlining features than Class::MOP itself does.
1664 =item B<< $metaclass->make_immutable(%options) >>
1666 This method will create an immutable transformer and uses it to make
1667 the class and its metaclass object immutable.
1669 Details of how immutabilization works are in L<Class::MOP::Immutable>
1672 =item B<< $metaclass->make_mutable >>
1674 Calling this method reverse the immutabilization transformation.
1676 =item B<< $metaclass->immutable_transformer >>
1678 If the class has been made immutable previously, this returns the
1679 L<Class::MOP::Immutable> object that was created to do the
1682 If the class was never made immutable, this method will die.
1686 =head2 Method Modifiers
1688 Method modifiers are hooks which allow a method to be wrapped with
1689 I<before>, I<after> and I<around> method modifiers. Every time a
1690 method is called, it's modifiers are also called.
1692 A class can modify its own methods, as well as methods defined in
1695 =head3 How method modifiers work?
1697 Method modifiers work by wrapping the original method and then
1698 replacing it in the class's symbol table. The wrappers will handle
1699 calling all the modifiers in the appropriate order and preserving the
1700 calling context for the original method.
1702 The return values of C<before> and C<after> modifiers are
1703 ignored. This is because their purpose is B<not> to filter the input
1704 and output of the primary method (this is done with an I<around>
1707 This may seem like an odd restriction to some, but doing this allows
1708 for simple code to be added at the beginning or end of a method call
1709 without altering the function of the wrapped method or placing any
1710 extra responsibility on the code of the modifier.
1712 Of course if you have more complex needs, you can use the C<around>
1713 modifier which allows you to change both the parameters passed to the
1714 wrapped method, as well as its return value.
1716 Before and around modifiers are called in last-defined-first-called
1717 order, while after modifiers are called in first-defined-first-called
1718 order. So the call tree might looks something like this:
1730 =head3 What is the performance impact?
1732 Of course there is a performance cost associated with method
1733 modifiers, but we have made every effort to make that cost directly
1734 proportional to the number of modifier features you utilize.
1736 The wrapping method does it's best to B<only> do as much work as it
1737 absolutely needs to. In order to do this we have moved some of the
1738 performance costs to set-up time, where they are easier to amortize.
1740 All this said, our benchmarks have indicated the following:
1742 simple wrapper with no modifiers 100% slower
1743 simple wrapper with simple before modifier 400% slower
1744 simple wrapper with simple after modifier 450% slower
1745 simple wrapper with simple around modifier 500-550% slower
1746 simple wrapper with all 3 modifiers 1100% slower
1748 These numbers may seem daunting, but you must remember, every feature
1749 comes with some cost. To put things in perspective, just doing a
1750 simple C<AUTOLOAD> which does nothing but extract the name of the
1751 method called and return it costs about 400% over a normal method
1756 =item B<< $metaclass->add_before_method_modifier($method_name, $code) >>
1758 This wraps the specified method with the supplied subroutine
1759 reference. The modifier will be called as a method itself, and will
1760 receive the same arguments as are passed to the method.
1762 When the modifier exits, the wrapped method will be called.
1764 The return value of the modifier will be ignored.
1766 =item B<< $metaclass->add_after_method_modifier($method_name, $code) >>
1768 This wraps the specified method with the supplied subroutine
1769 reference. The modifier will be called as a method itself, and will
1770 receive the same arguments as are passed to the method.
1772 When the wrapped methods exits, the modifier will be called.
1774 The return value of the modifier will be ignored.
1776 =item B<< $metaclass->add_around_method_modifier($method_name, $code) >>
1778 This wraps the specified method with the supplied subroutine
1781 The first argument passed to the modifier will be a subroutine
1782 reference to the wrapped method. The second argument is the object,
1783 and after that come any arguments passed when the method is called.
1785 The around modifier can choose to call the original method, as well as
1786 what arguments to pass if it does so.
1788 The return value of the modifier is what will be seen by the caller.
1792 =head2 Introspection
1796 =item B<< Class::MOP::Class->meta >>
1798 This will return a L<Class::MOP::Class> instance for this class.
1800 It should also be noted that L<Class::MOP> will actually bootstrap
1801 this module by installing a number of attribute meta-objects into its
1808 Stevan Little E<lt>stevan@iinteractive.comE<gt>
1810 =head1 COPYRIGHT AND LICENSE
1812 Copyright 2006-2009 by Infinity Interactive, Inc.
1814 L<http://www.iinteractive.com>
1816 This library is free software; you can redistribute it and/or modify
1817 it under the same terms as Perl itself.