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';
16 our $VERSION = '0.83';
17 $VERSION = eval $VERSION;
18 our $AUTHORITY = 'cpan:STEVAN';
20 use base 'Class::MOP::Module';
30 $package_name = shift;
33 $package_name = $options{package};
36 (defined $package_name && $package_name && !ref($package_name))
37 || confess "You must pass a package name and it cannot be blessed";
39 return Class::MOP::get_metaclass_by_name($package_name)
40 || $class->_construct_class_instance(package => $package_name, @_);
43 sub construct_class_instance {
44 Carp::cluck('The construct_class_instance method has been made private.'
45 . " The public version is deprecated and will be removed in a future release.\n");
46 shift->_construct_class_instance(@_);
49 # NOTE: (meta-circularity)
50 # this is a special form of _construct_instance
51 # (see below), which is used to construct class
52 # meta-object instances for any Class::MOP::*
53 # class. All other classes will use the more
54 # normal &construct_instance.
55 sub _construct_class_instance {
57 my $options = @_ == 1 ? $_[0] : {@_};
58 my $package_name = $options->{package};
59 (defined $package_name && $package_name)
60 || confess "You must pass a package name";
62 # return the metaclass if we have it cached,
63 # and it is still defined (it has not been
64 # reaped by DESTROY yet, which can happen
65 # annoyingly enough during global destruction)
67 if (defined(my $meta = Class::MOP::get_metaclass_by_name($package_name))) {
72 # we need to deal with the possibility
73 # of class immutability here, and then
74 # get the name of the class appropriately
76 ? ($class->is_immutable
77 ? $class->get_mutable_metaclass_name()
81 # now create the metaclass
83 if ($class eq 'Class::MOP::Class') {
84 $meta = $class->_new($options);
88 # it is safe to use meta here because
89 # class will always be a subclass of
90 # Class::MOP::Class, which defines meta
91 $meta = $class->meta->_construct_instance($options)
94 # and check the metaclass compatibility
95 $meta->_check_metaclass_compatibility();
97 Class::MOP::store_metaclass_by_name($package_name, $meta);
100 # we need to weaken any anon classes
101 # so that they can call DESTROY properly
102 Class::MOP::weaken_metaclass($package_name) if $meta->is_anon_class;
109 my $options = @_ == 1 ? $_[0] : {@_};
112 # inherited from Class::MOP::Package
113 'package' => $options->{package},
116 # since the following attributes will
117 # actually be loaded from the symbol
118 # table, and actually bypass the instance
119 # entirely, we can just leave these things
120 # listed here for reference, because they
121 # should not actually have a value associated
123 'namespace' => \undef,
125 # inherited from Class::MOP::Module
127 'authority' => \undef,
129 # defined in Class::MOP::Class
130 'superclasses' => \undef,
134 'attribute_metaclass' =>
135 ( $options->{'attribute_metaclass'} || 'Class::MOP::Attribute' ),
136 'method_metaclass' =>
137 ( $options->{'method_metaclass'} || 'Class::MOP::Method' ),
138 'wrapped_method_metaclass' => (
139 $options->{'wrapped_method_metaclass'}
140 || 'Class::MOP::Method::Wrapped'
142 'instance_metaclass' =>
143 ( $options->{'instance_metaclass'} || 'Class::MOP::Instance' ),
144 'immutable_trait' => (
145 $options->{'immutable_trait'}
146 || 'Class::MOP::Class::Immutable::Trait'
148 'constructor_name' => ( $options->{constructor_name} || 'new' ),
149 'constructor_class' => (
150 $options->{constructor_class} || 'Class::MOP::Method::Constructor'
152 'destructor_class' => $options->{destructor_class},
156 sub reset_package_cache_flag { (shift)->{'_package_cache_flag'} = undef }
157 sub update_package_cache_flag {
160 # we can manually update the cache number
161 # since we are actually adding the method
162 # to our cache as well. This avoids us
163 # having to regenerate the method_map.
165 $self->{'_package_cache_flag'} = Class::MOP::check_package_cache_flag($self->name);
169 sub check_metaclass_compatibility {
170 Carp::cluck('The check_metaclass_compatibility method has been made private.'
171 . " The public version is deprecated and will be removed in a future release.\n");
172 shift->_check_metaclass_compatibility(@_);
175 sub _check_metaclass_compatibility {
178 # this is always okay ...
179 return if ref($self) eq 'Class::MOP::Class' &&
180 $self->instance_metaclass eq 'Class::MOP::Instance';
182 my @class_list = $self->linearized_isa;
183 shift @class_list; # shift off $self->name
185 foreach my $superclass_name (@class_list) {
186 my $super_meta = Class::MOP::get_metaclass_by_name($superclass_name) || next;
189 # we need to deal with the possibility
190 # of class immutability here, and then
191 # get the name of the class appropriately
193 = $super_meta->is_immutable
194 ? $super_meta->get_mutable_metaclass_name()
197 ($self->isa($super_meta_type))
198 || confess "Class::MOP::class_of(" . $self->name . ") => ("
199 . (ref($self)) . ")" . " is not compatible with the " .
200 "Class::MOP::class_of(".$superclass_name . ") => ("
201 . ($super_meta_type) . ")";
203 # we also need to check that instance metaclasses
204 # are compatibile in the same the class.
205 ($self->instance_metaclass->isa($super_meta->instance_metaclass))
206 || confess "Class::MOP::class_of(" . $self->name . ")->instance_metaclass => (" . ($self->instance_metaclass) . ")" .
207 " is not compatible with the " .
208 "Class::MOP::class_of(" . $superclass_name . ")->instance_metaclass => (" . ($super_meta->instance_metaclass) . ")";
216 # this should be sufficient, if you have a
217 # use case where it is not, write a test and
219 my $ANON_CLASS_SERIAL = 0;
222 # we need a sufficiently annoying prefix
223 # this should suffice for now, this is
224 # used in a couple of places below, so
225 # need to put it up here for now.
226 my $ANON_CLASS_PREFIX = 'Class::MOP::Class::__ANON__::SERIAL::';
230 no warnings 'uninitialized';
231 $self->name =~ /^$ANON_CLASS_PREFIX/;
234 sub create_anon_class {
235 my ($class, %options) = @_;
236 my $package_name = $ANON_CLASS_PREFIX . ++$ANON_CLASS_SERIAL;
237 return $class->create($package_name, %options);
241 # this will only get called for
242 # anon-classes, all other calls
243 # are assumed to occur during
244 # global destruction and so don't
245 # really need to be handled explicitly
249 return if Class::MOP::in_global_destruction(); # it'll happen soon anyway and this just makes things more complicated
251 no warnings 'uninitialized';
252 return unless $self->name =~ /^$ANON_CLASS_PREFIX/;
253 # Moose does a weird thing where it replaces the metaclass for
254 # class when fixing metaclass incompatibility. In that case,
255 # we don't want to clean out the namespace now. We can detect
256 # that because Moose will explicitly update the singleton
257 # cache in Class::MOP.
258 my $current_meta = Class::MOP::get_metaclass_by_name($self->name);
259 return if $current_meta ne $self;
261 my ($serial_id) = ($self->name =~ /^$ANON_CLASS_PREFIX(\d+)/);
263 foreach my $key (keys %{$ANON_CLASS_PREFIX . $serial_id}) {
264 delete ${$ANON_CLASS_PREFIX . $serial_id}{$key};
266 delete ${'main::' . $ANON_CLASS_PREFIX}{$serial_id . '::'};
271 # creating classes with MOP ...
274 my ( $class, @args ) = @_;
276 unshift @args, 'package' if @args % 2 == 1;
278 my (%options) = @args;
279 my $package_name = $options{package};
281 (ref $options{superclasses} eq 'ARRAY')
282 || confess "You must pass an ARRAY ref of superclasses"
283 if exists $options{superclasses};
285 (ref $options{attributes} eq 'ARRAY')
286 || confess "You must pass an ARRAY ref of attributes"
287 if exists $options{attributes};
289 (ref $options{methods} eq 'HASH')
290 || confess "You must pass a HASH ref of methods"
291 if exists $options{methods};
293 my (%initialize_options) = @args;
294 delete @initialize_options{qw(
302 my $meta = $class->initialize( $package_name => %initialize_options );
304 $meta->_instantiate_module( $options{version}, $options{authority} );
307 $meta->add_method('meta' => sub {
308 $class->initialize(ref($_[0]) || $_[0]);
311 $meta->superclasses(@{$options{superclasses}})
312 if exists $options{superclasses};
314 # process attributes first, so that they can
315 # install accessors, but locally defined methods
316 # can then overwrite them. It is maybe a little odd, but
317 # I think this should be the order of things.
318 if (exists $options{attributes}) {
319 foreach my $attr (@{$options{attributes}}) {
320 $meta->add_attribute($attr);
323 if (exists $options{methods}) {
324 foreach my $method_name (keys %{$options{methods}}) {
325 $meta->add_method($method_name, $options{methods}->{$method_name});
334 # all these attribute readers will be bootstrapped
335 # away in the Class::MOP bootstrap section
337 sub get_attribute_map { $_[0]->{'attributes'} }
338 sub attribute_metaclass { $_[0]->{'attribute_metaclass'} }
339 sub method_metaclass { $_[0]->{'method_metaclass'} }
340 sub wrapped_method_metaclass { $_[0]->{'wrapped_method_metaclass'} }
341 sub instance_metaclass { $_[0]->{'instance_metaclass'} }
342 sub immutable_trait { $_[0]->{'immutable_trait'} }
343 sub constructor_class { $_[0]->{'constructor_class'} }
344 sub constructor_name { $_[0]->{'constructor_name'} }
345 sub destructor_class { $_[0]->{'destructor_class'} }
347 # Instance Construction & Cloning
353 # we need to protect the integrity of the
354 # Class::MOP::Class singletons here, so we
355 # delegate this to &construct_class_instance
356 # which will deal with the singletons
357 return $class->_construct_class_instance(@_)
358 if $class->name->isa('Class::MOP::Class');
359 return $class->_construct_instance(@_);
362 sub construct_instance {
363 Carp::cluck('The construct_instance method has been made private.'
364 . " The public version is deprecated and will be removed in a future release.\n");
365 shift->_construct_instance(@_);
368 sub _construct_instance {
370 my $params = @_ == 1 ? $_[0] : {@_};
371 my $meta_instance = $class->get_meta_instance();
372 my $instance = $meta_instance->create_instance();
373 foreach my $attr ($class->get_all_attributes()) {
374 $attr->initialize_instance_slot($meta_instance, $instance, $params);
377 # this will only work for a HASH instance type
378 if ($class->is_anon_class) {
379 (Scalar::Util::reftype($instance) eq 'HASH')
380 || confess "Currently only HASH based instances are supported with instance of anon-classes";
382 # At some point we should make this official
383 # as a reserved slot name, but right now I am
384 # going to keep it here.
385 # my $RESERVED_MOP_SLOT = '__MOP__';
386 $instance->{'__MOP__'} = $class;
392 sub get_meta_instance {
394 $self->{'_meta_instance'} ||= $self->_create_meta_instance();
397 sub create_meta_instance {
398 Carp::cluck('The create_meta_instance method has been made private.'
399 . " The public version is deprecated and will be removed in a future release.\n");
400 shift->_create_meta_instance(@_);
403 sub _create_meta_instance {
406 my $instance = $self->instance_metaclass->new(
407 associated_metaclass => $self,
408 attributes => [ $self->get_all_attributes() ],
411 $self->add_meta_instance_dependencies()
412 if $instance->is_dependent_on_superclasses();
419 my $instance = shift;
420 (blessed($instance) && $instance->isa($class->name))
421 || confess "You must pass an instance of the metaclass (" . (ref $class ? $class->name : $class) . "), not ($instance)";
424 # we need to protect the integrity of the
425 # Class::MOP::Class singletons here, they
426 # should not be cloned.
427 return $instance if $instance->isa('Class::MOP::Class');
428 $class->_clone_instance($instance, @_);
432 Carp::cluck('The clone_instance method has been made private.'
433 . " The public version is deprecated and will be removed in a future release.\n");
434 shift->_clone_instance(@_);
437 sub _clone_instance {
438 my ($class, $instance, %params) = @_;
440 || confess "You can only clone instances, ($instance) is not a blessed instance";
441 my $meta_instance = $class->get_meta_instance();
442 my $clone = $meta_instance->clone_instance($instance);
443 foreach my $attr ($class->get_all_attributes()) {
444 if ( defined( my $init_arg = $attr->init_arg ) ) {
445 if (exists $params{$init_arg}) {
446 $attr->set_value($clone, $params{$init_arg});
453 sub rebless_instance {
454 my ($self, $instance, %params) = @_;
456 my $old_metaclass = Class::MOP::class_of($instance);
458 my $old_class = $old_metaclass ? $old_metaclass->name : blessed($instance);
459 $self->name->isa($old_class)
460 || confess "You may rebless only into a subclass of ($old_class), of which (". $self->name .") isn't.";
462 $old_metaclass->rebless_instance_away($instance, $self, %params)
465 my $meta_instance = $self->get_meta_instance();
468 # we use $_[1] here because of t/306_rebless_overload.t regressions on 5.8.8
469 $meta_instance->rebless_instance_structure($_[1], $self);
471 foreach my $attr ( $self->get_all_attributes ) {
472 if ( $attr->has_value($instance) ) {
473 if ( defined( my $init_arg = $attr->init_arg ) ) {
474 $params{$init_arg} = $attr->get_value($instance)
475 unless exists $params{$init_arg};
478 $attr->set_value($instance, $attr->get_value($instance));
483 foreach my $attr ($self->get_all_attributes) {
484 $attr->initialize_instance_slot($meta_instance, $instance, \%params);
490 sub rebless_instance_away {
491 # this intentionally does nothing, it is just a hook
498 my $var_spec = { sigil => '@', type => 'ARRAY', name => 'ISA' };
501 @{$self->get_package_symbol($var_spec)} = @supers;
504 # on 5.8 and below, we need to call
505 # a method to get Perl to detect
506 # a cycle in the class hierarchy
507 my $class = $self->name;
511 # we need to check the metaclass
512 # compatibility here so that we can
513 # be sure that the superclass is
514 # not potentially creating an issues
515 # we don't know about
517 $self->_check_metaclass_compatibility();
518 $self->update_meta_instance_dependencies();
520 @{$self->get_package_symbol($var_spec)};
525 my $super_class = $self->name;
527 return @{ $super_class->mro::get_isarev() };
532 return @{ mro::get_linear_isa( (shift)->name ) };
535 sub class_precedence_list {
537 my $name = $self->name;
539 unless (Class::MOP::IS_RUNNING_ON_5_10()) {
541 # We need to check for circular inheritance here
542 # if we are are not on 5.10, cause 5.8 detects it
543 # late. This will do nothing if all is well, and
544 # blow up otherwise. Yes, it's an ugly hack, better
545 # suggestions are welcome.
547 ($name || return)->isa('This is a test for circular inheritance')
550 # if our mro is c3, we can
551 # just grab the linear_isa
552 if (mro::get_mro($name) eq 'c3') {
553 return @{ mro::get_linear_isa($name) }
557 # we can't grab the linear_isa for dfs
558 # since it has all the duplicates
563 $self->initialize($_)->class_precedence_list()
564 } $self->superclasses()
571 sub wrap_method_body {
572 my ( $self, %args ) = @_;
574 ('CODE' eq ref $args{body})
575 || confess "Your code block must be a CODE reference";
577 $self->method_metaclass->wrap(
578 package_name => $self->name,
584 my ($self, $method_name, $method) = @_;
585 (defined $method_name && $method_name)
586 || confess "You must define a method name";
589 if (blessed($method)) {
590 $body = $method->body;
591 if ($method->package_name ne $self->name) {
592 $method = $method->clone(
593 package_name => $self->name,
595 ) if $method->can('clone');
600 $method = $self->wrap_method_body( body => $body, name => $method_name );
603 $method->attach_to_class($self);
605 # This used to call get_method_map, which meant we would build all
606 # the method objects for the class just because we added one
607 # method. This is hackier, but quicker too.
608 $self->{methods}{$method_name} = $method;
610 my $full_method_name = ($self->name . '::' . $method_name);
611 $self->add_package_symbol(
612 { sigil => '&', type => 'CODE', name => $method_name },
613 Class::MOP::subname($full_method_name => $body)
618 my $fetch_and_prepare_method = sub {
619 my ($self, $method_name) = @_;
620 my $wrapped_metaclass = $self->wrapped_method_metaclass;
622 my $method = $self->get_method($method_name);
623 # if we dont have local ...
625 # try to find the next method
626 $method = $self->find_next_method_by_name($method_name);
627 # die if it does not exist
629 || confess "The method '$method_name' was not found in the inheritance hierarchy for " . $self->name;
630 # and now make sure to wrap it
631 # even if it is already wrapped
632 # because we need a new sub ref
633 $method = $wrapped_metaclass->wrap($method);
636 # now make sure we wrap it properly
637 $method = $wrapped_metaclass->wrap($method)
638 unless $method->isa($wrapped_metaclass);
640 $self->add_method($method_name => $method);
644 sub add_before_method_modifier {
645 my ($self, $method_name, $method_modifier) = @_;
646 (defined $method_name && $method_name)
647 || confess "You must pass in a method name";
648 my $method = $fetch_and_prepare_method->($self, $method_name);
649 $method->add_before_modifier(
650 Class::MOP::subname(':before' => $method_modifier)
654 sub add_after_method_modifier {
655 my ($self, $method_name, $method_modifier) = @_;
656 (defined $method_name && $method_name)
657 || confess "You must pass in a method name";
658 my $method = $fetch_and_prepare_method->($self, $method_name);
659 $method->add_after_modifier(
660 Class::MOP::subname(':after' => $method_modifier)
664 sub add_around_method_modifier {
665 my ($self, $method_name, $method_modifier) = @_;
666 (defined $method_name && $method_name)
667 || confess "You must pass in a method name";
668 my $method = $fetch_and_prepare_method->($self, $method_name);
669 $method->add_around_modifier(
670 Class::MOP::subname(':around' => $method_modifier)
675 # the methods above used to be named like this:
676 # ${pkg}::${method}:(before|after|around)
677 # but this proved problematic when using one modifier
678 # to wrap multiple methods (something which is likely
679 # to happen pretty regularly IMO). So instead of naming
680 # it like this, I have chosen to just name them purely
681 # with their modifier names, like so:
682 # :(before|after|around)
683 # The fact is that in a stack trace, it will be fairly
684 # evident from the context what method they are attached
685 # to, and so don't need the fully qualified name.
689 Carp::cluck("The alias_method method is deprecated. Use add_method instead.\n");
691 shift->add_method(@_);
695 my ($self, $method_name) = @_;
696 (defined $method_name && $method_name)
697 || confess "You must define a method name";
699 exists $self->{methods}{$method_name} || exists $self->get_method_map->{$method_name};
703 my ($self, $method_name) = @_;
704 (defined $method_name && $method_name)
705 || confess "You must define a method name";
707 return $self->{methods}{$method_name} || $self->get_method_map->{$method_name};
711 my ($self, $method_name) = @_;
712 (defined $method_name && $method_name)
713 || confess "You must define a method name";
715 my $removed_method = delete $self->get_method_map->{$method_name};
717 $self->remove_package_symbol(
718 { sigil => '&', type => 'CODE', name => $method_name }
721 $removed_method->detach_from_class if $removed_method;
723 $self->update_package_cache_flag; # still valid, since we just removed the method from the map
725 return $removed_method;
728 sub get_method_list {
730 keys %{$self->get_method_map};
733 sub find_method_by_name {
734 my ($self, $method_name) = @_;
735 (defined $method_name && $method_name)
736 || confess "You must define a method name to find";
737 foreach my $class ($self->linearized_isa) {
738 # fetch the meta-class ...
739 my $meta = $self->initialize($class);
740 return $meta->get_method($method_name)
741 if $meta->has_method($method_name);
746 sub get_all_methods {
748 my %methods = map { %{ $self->initialize($_)->get_method_map } } reverse $self->linearized_isa;
749 return values %methods;
752 sub compute_all_applicable_methods {
753 Carp::cluck('The compute_all_applicable_methods method is deprecated.'
754 . " Use get_all_methods instead.\n");
759 class => $_->package_name,
760 code => $_, # sigh, overloading
762 } shift->get_all_methods(@_);
765 sub get_all_method_names {
768 grep { $uniq{$_}++ == 0 } map { $_->name } $self->get_all_methods;
771 sub find_all_methods_by_name {
772 my ($self, $method_name) = @_;
773 (defined $method_name && $method_name)
774 || confess "You must define a method name to find";
776 foreach my $class ($self->linearized_isa) {
777 # fetch the meta-class ...
778 my $meta = $self->initialize($class);
780 name => $method_name,
782 code => $meta->get_method($method_name)
783 } if $meta->has_method($method_name);
788 sub find_next_method_by_name {
789 my ($self, $method_name) = @_;
790 (defined $method_name && $method_name)
791 || confess "You must define a method name to find";
792 my @cpl = $self->linearized_isa;
793 shift @cpl; # discard ourselves
794 foreach my $class (@cpl) {
795 # fetch the meta-class ...
796 my $meta = $self->initialize($class);
797 return $meta->get_method($method_name)
798 if $meta->has_method($method_name);
807 # either we have an attribute object already
808 # or we need to create one from the args provided
809 my $attribute = blessed($_[0]) ? $_[0] : $self->attribute_metaclass->new(@_);
810 # make sure it is derived from the correct type though
811 ($attribute->isa('Class::MOP::Attribute'))
812 || confess "Your attribute must be an instance of Class::MOP::Attribute (or a subclass)";
814 # first we attach our new attribute
815 # because it might need certain information
816 # about the class which it is attached to
817 $attribute->attach_to_class($self);
819 # then we remove attributes of a conflicting
820 # name here so that we can properly detach
821 # the old attr object, and remove any
822 # accessors it would have generated
823 if ( $self->has_attribute($attribute->name) ) {
824 $self->remove_attribute($attribute->name);
826 $self->invalidate_meta_instances();
829 # then onto installing the new accessors
830 $self->get_attribute_map->{$attribute->name} = $attribute;
832 # invalidate package flag here
833 my $e = do { local $@; eval { $attribute->install_accessors() }; $@ };
835 $self->remove_attribute($attribute->name);
842 sub update_meta_instance_dependencies {
845 if ( $self->{meta_instance_dependencies} ) {
846 return $self->add_meta_instance_dependencies;
850 sub add_meta_instance_dependencies {
853 $self->remove_meta_instance_dependencies;
855 my @attrs = $self->get_all_attributes();
858 my @classes = grep { not $seen{$_->name}++ } map { $_->associated_class } @attrs;
860 foreach my $class ( @classes ) {
861 $class->add_dependent_meta_instance($self);
864 $self->{meta_instance_dependencies} = \@classes;
867 sub remove_meta_instance_dependencies {
870 if ( my $classes = delete $self->{meta_instance_dependencies} ) {
871 foreach my $class ( @$classes ) {
872 $class->remove_dependent_meta_instance($self);
882 sub add_dependent_meta_instance {
883 my ( $self, $metaclass ) = @_;
884 push @{ $self->{dependent_meta_instances} }, $metaclass;
887 sub remove_dependent_meta_instance {
888 my ( $self, $metaclass ) = @_;
889 my $name = $metaclass->name;
890 @$_ = grep { $_->name ne $name } @$_ for $self->{dependent_meta_instances};
893 sub invalidate_meta_instances {
895 $_->invalidate_meta_instance() for $self, @{ $self->{dependent_meta_instances} };
898 sub invalidate_meta_instance {
900 undef $self->{_meta_instance};
904 my ($self, $attribute_name) = @_;
905 (defined $attribute_name && $attribute_name)
906 || confess "You must define an attribute name";
907 exists $self->get_attribute_map->{$attribute_name};
911 my ($self, $attribute_name) = @_;
912 (defined $attribute_name && $attribute_name)
913 || confess "You must define an attribute name";
914 return $self->get_attribute_map->{$attribute_name}
916 # this will return undef anyway, so no need ...
917 # if $self->has_attribute($attribute_name);
921 sub remove_attribute {
922 my ($self, $attribute_name) = @_;
923 (defined $attribute_name && $attribute_name)
924 || confess "You must define an attribute name";
925 my $removed_attribute = $self->get_attribute_map->{$attribute_name};
926 return unless defined $removed_attribute;
927 delete $self->get_attribute_map->{$attribute_name};
928 $self->invalidate_meta_instances();
929 $removed_attribute->remove_accessors();
930 $removed_attribute->detach_from_class();
931 return $removed_attribute;
934 sub get_attribute_list {
936 keys %{$self->get_attribute_map};
939 sub get_all_attributes {
941 my %attrs = map { %{ $self->initialize($_)->get_attribute_map } } reverse $self->linearized_isa;
942 return values %attrs;
945 sub compute_all_applicable_attributes {
946 Carp::cluck('The compute_all_applicable_attributes method has been deprecated.'
947 . " Use get_all_attributes instead.\n");
949 shift->get_all_attributes(@_);
952 sub find_attribute_by_name {
953 my ($self, $attr_name) = @_;
954 foreach my $class ($self->linearized_isa) {
955 # fetch the meta-class ...
956 my $meta = $self->initialize($class);
957 return $meta->get_attribute($attr_name)
958 if $meta->has_attribute($attr_name);
963 # check if we can reinitialize
967 # if any local attr is defined
968 return if $self->get_attribute_list;
970 # or any non-declared methods
971 if ( my @methods = values %{ $self->get_method_map } ) {
972 my $metaclass = $self->method_metaclass;
973 foreach my $method ( @methods ) {
974 return if $method->isa("Class::MOP::Method::Generated");
975 # FIXME do we need to enforce this too? return unless $method->isa($metaclass);
985 sub is_immutable { 0 }
986 sub immutable_transformer { return }
988 sub _immutable_options {
989 my ( $self, @args ) = @_;
992 inline_accessors => 1,
993 inline_constructor => 1,
994 inline_destructor => 0,
996 immutable_trait => $self->immutable_trait,
997 constructor_name => $self->constructor_name,
998 constructor_class => $self->constructor_class,
999 destructor_class => $self->destructor_class,
1004 sub make_immutable {
1005 my ( $self, @args ) = @_;
1007 if ( $self->is_mutable ) {
1008 $self->_initialize_immutable( $self->_immutable_options(@args) );
1009 $self->_rebless_as_immutable(@args);
1020 if ( $self->is_immutable ) {
1021 my @args = $self->immutable_options;
1022 $self->_rebless_as_mutable();
1023 $self->_remove_inlined_code(@args);
1024 delete $self->{__immutable};
1032 sub _rebless_as_immutable {
1033 my ( $self, @args ) = @_;
1035 $self->{__immutable}{original_class} = ref $self;
1037 bless $self => $self->_immutable_metaclass(@args);
1040 sub _immutable_metaclass {
1041 my ( $self, %args ) = @_;
1043 if ( my $class = $args{immutable_metaclass} ) {
1047 my $trait = $args{immutable_trait} = $self->immutable_trait
1048 || confess "no immutable trait specified for $self";
1050 my $meta_attr = $self->meta->find_attribute_by_name("immutable_trait");
1054 if ( $meta_attr and $trait eq $meta_attr->default ) {
1056 # if the trait is the same as the default we try and pick a predictable
1057 # name for the immutable metaclass
1058 $class_name = "Class::MOP::Class::Immutable::" . ref($self);
1062 = join( "::", "Class::MOP::Class::Immutable::CustomTrait", $trait,
1063 "ForMetaClass", ref($self) );
1066 if ( Class::MOP::is_class_loaded($class_name) ) {
1067 if ( $class_name->isa($trait) ) {
1072 "$class_name is already defined but does not inherit $trait";
1076 my @super = ( $trait, ref($self) );
1078 my $meta = Class::MOP::Class->initialize($class_name);
1079 $meta->superclasses(@super);
1081 $meta->make_immutable;
1087 sub _remove_inlined_code {
1090 $self->remove_method( $_->name ) for $self->_inlined_methods;
1092 delete $self->{__immutable}{inlined_methods};
1095 sub _inlined_methods { @{ $_[0]{__immutable}{inlined_methods} || [] } }
1097 sub _add_inlined_method {
1098 my ( $self, $method ) = @_;
1100 push @{ $self->{__immutable}{inlined_methods} ||= [] }, $method;
1103 sub _initialize_immutable {
1104 my ( $self, %args ) = @_;
1106 $self->{__immutable}{options} = \%args;
1107 $self->_install_inlined_code(%args);
1110 sub _install_inlined_code {
1111 my ( $self, %args ) = @_;
1114 $self->_inline_accessors(%args) if $args{inline_accessors};
1115 $self->_inline_constructor(%args) if $args{inline_constructor};
1116 $self->_inline_destructor(%args) if $args{inline_destructor};
1119 sub _rebless_as_mutable {
1122 bless $self, $self->get_mutable_metaclass_name;
1127 sub _inline_accessors {
1130 foreach my $attr_name ( $self->get_attribute_list ) {
1131 $self->get_attribute($attr_name)->install_accessors(1);
1135 sub _inline_constructor {
1136 my ( $self, %args ) = @_;
1138 my $name = $args{constructor_name};
1140 #if ( my $existing = $self->name->can($args{constructor_name}) ) {
1141 # if ( refaddr($existing) == refaddr(\&Moose::Object::new) ) {
1143 unless ( $args{replace_constructor}
1144 or !$self->has_method($name) ) {
1145 my $class = $self->name;
1146 warn "Not inlining a constructor for $class since it defines"
1147 . " its own constructor.\n"
1148 . "If you are certain you don't need to inline your"
1149 . " constructor, specify inline_constructor => 0 in your"
1150 . " call to $class->meta->make_immutable\n";
1154 my $constructor_class = $args{constructor_class};
1156 Class::MOP::load_class($constructor_class);
1158 my $constructor = $constructor_class->new(
1162 package_name => $self->name,
1166 if ( $args{replace_constructor} or $constructor->can_be_inlined ) {
1167 $self->add_method( $name => $constructor );
1168 $self->_add_inlined_method($constructor);
1172 sub _inline_destructor {
1173 my ( $self, %args ) = @_;
1175 ( exists $args{destructor_class} )
1176 || confess "The 'inline_destructor' option is present, but "
1177 . "no destructor class was specified";
1179 my $destructor_class = $args{destructor_class};
1181 Class::MOP::load_class($destructor_class);
1183 return unless $destructor_class->is_needed($self);
1185 my $destructor = $destructor_class->new(
1188 package_name => $self->name,
1192 $self->add_method( 'DESTROY' => $destructor );
1194 $self->_add_inlined_method($destructor);
1205 Class::MOP::Class - Class Meta Object
1209 # assuming that class Foo
1210 # has been defined, you can
1212 # use this for introspection ...
1214 # add a method to Foo ...
1215 Foo->meta->add_method( 'bar' => sub {...} )
1217 # get a list of all the classes searched
1218 # the method dispatcher in the correct order
1219 Foo->meta->class_precedence_list()
1221 # remove a method from Foo
1222 Foo->meta->remove_method('bar');
1224 # or use this to actually create classes ...
1226 Class::MOP::Class->create(
1229 superclasses => ['Foo'],
1231 Class::MOP::Attribute->new('$bar'),
1232 Class::MOP::Attribute->new('$baz'),
1235 calculate_bar => sub {...},
1236 construct_baz => sub {...}
1243 The Class Protocol is the largest and most complex part of the
1244 Class::MOP meta-object protocol. It controls the introspection and
1245 manipulation of Perl 5 classes, and it can create them as well. The
1246 best way to understand what this module can do, is to read the
1247 documentation for each of its methods.
1251 C<Class::MOP::Class> is a subclass of L<Class::MOP::Module>.
1255 =head2 Class construction
1257 These methods all create new C<Class::MOP::Class> objects. These
1258 objects can represent existing classes, or they can be used to create
1259 new classes from scratch.
1261 The metaclass object for a given class is a singleton. If you attempt
1262 to create a metaclass for the same class twice, you will just get the
1267 =item B<< Class::MOP::Class->create($package_name, %options) >>
1269 This method creates a new C<Class::MOP::Class> object with the given
1270 package name. It accepts a number of options.
1276 An optional version number for the newly created package.
1280 An optional authority for the newly created package.
1282 =item * superclasses
1284 An optional array reference of superclass names.
1288 An optional hash reference of methods for the class. The keys of the
1289 hash reference are method names, and values are subroutine references.
1293 An optional array reference of attributes.
1295 An attribute can be passed as an existing L<Class::MOP::Attribute>
1296 object, I<or> or as a hash reference of options which will be passed
1297 to the attribute metaclass's constructor.
1301 =item B<< Class::MOP::Class->create_anon_class(%options) >>
1303 This method works just like C<< Class::MOP::Class->create >> but it
1304 creates an "anonymous" class. In fact, the class does have a name, but
1305 that name is a unique name generated internally by this module.
1307 It accepts the same C<superclasses>, C<methods>, and C<attributes>
1308 parameters that C<create> accepts.
1310 Anonymous classes are destroyed once the metaclass they are attached
1311 to goes out of scope, and will be removed from Perl's internal symbol
1314 All instances of an anonymous class keep a special reference to the
1315 metaclass object, which prevents the metaclass from going out of scope
1316 while any instances exist.
1318 This only works if the instance if based on a hash reference, however.
1320 =item B<< Class::MOP::Class->initialize($package_name, %options) >>
1322 This method will initialize a C<Class::MOP::Class> object for the
1323 named package. Unlike C<create>, this method I<will not> create a new
1326 The purpose of this method is to retrieve a C<Class::MOP::Class>
1327 object for introspecting an existing class.
1329 If an existing C<Class::MOP::Class> object exists for the named
1330 package, it will be returned, and any options provided will be
1333 If the object does not yet exist, it will be created.
1335 The valid options that can be passed to this method are
1336 C<attribute_metaclass>, C<method_metaclass>,
1337 C<wrapped_method_metaclass>, and C<instance_metaclass>. These are all
1338 optional, and default to the appropriate class in the C<Class::MOP>
1343 =head2 Object instance construction and cloning
1345 These methods are all related to creating and/or cloning object
1350 =item B<< $metaclass->clone_object($instance, %params) >>
1352 This method clones an existing object instance. Any parameters you
1353 provide are will override existing attribute values in the object.
1355 This is a convenience method for cloning an object instance, then
1356 blessing it into the appropriate package.
1358 You could implement a clone method in your class, using this method:
1361 my ($self, %params) = @_;
1362 $self->meta->clone_object($self, %params);
1365 =item B<< $metaclass->rebless_instance($instance, %params) >>
1367 This method changes the class of C<$instance> to the metaclass's class.
1369 You can only rebless an instance into a subclass of its current
1370 class. If you pass any additional parameters, these will be treated
1371 like constructor parameters and used to initialize the object's
1372 attributes. Any existing attributes that are already set will be
1375 Before reblessing the instance, this method will call
1376 C<rebless_instance_away> on the instance's current metaclass. This method
1377 will be passed the instance, the new metaclass, and any parameters
1378 specified to C<rebless_instance>. By default, C<rebless_instance_away>
1379 does nothing; it is merely a hook.
1381 =item B<< $metaclass->new_object(%params) >>
1383 This method is used to create a new object of the metaclass's
1384 class. Any parameters you provide are used to initialize the
1385 instance's attributes.
1387 =item B<< $metaclass->instance_metaclass >>
1389 Returns the class name of the instance metaclass, see
1390 L<Class::MOP::Instance> for more information on the instance
1393 =item B<< $metaclass->get_meta_instance >>
1395 Returns an instance of the C<instance_metaclass> to be used in the
1396 construction of a new instance of the class.
1400 =head2 Informational predicates
1402 These are a few predicate methods for asking information about the
1407 =item B<< $metaclass->is_anon_class >>
1409 This returns true if the class was created by calling C<<
1410 Class::MOP::Class->create_anon_class >>.
1412 =item B<< $metaclass->is_mutable >>
1414 This returns true if the class is still mutable.
1416 =item B<< $metaclass->is_immutable >>
1418 This returns true if the class has been made immutable.
1420 =item B<< $metaclass->is_pristine >>
1422 A class is I<not> pristine if it has non-inherited attributes or if it
1423 has any generated methods.
1427 =head2 Inheritance Relationships
1431 =item B<< $metaclass->superclasses(@superclasses) >>
1433 This is a read-write accessor which represents the superclass
1434 relationships of the metaclass's class.
1436 This is basically sugar around getting and setting C<@ISA>.
1438 =item B<< $metaclass->class_precedence_list >>
1440 This returns a list of all of the class's ancestor classes. The
1441 classes are returned in method dispatch order.
1443 =item B<< $metaclass->linearized_isa >>
1445 This returns a list based on C<class_precedence_list> but with all
1448 =item B<< $metaclass->subclasses >>
1450 This returns a list of subclasses for this class.
1454 =head2 Method introspection and creation
1456 These methods allow you to introspect a class's methods, as well as
1457 add, remove, or change methods.
1459 Determining what is truly a method in a Perl 5 class requires some
1460 heuristics (aka guessing).
1462 Methods defined outside the package with a fully qualified name (C<sub
1463 Package::name { ... }>) will be included. Similarly, methods named
1464 with a fully qualified name using L<Sub::Name> are also included.
1466 However, we attempt to ignore imported functions.
1468 Ultimately, we are using heuristics to determine what truly is a
1469 method in a class, and these heuristics may get the wrong answer in
1470 some edge cases. However, for most "normal" cases the heuristics work
1475 =item B<< $metaclass->get_method($method_name) >>
1477 This will return a L<Class::MOP::Method> for the specified
1478 C<$method_name>. If the class does not have the specified method, it
1481 =item B<< $metaclass->has_method($method_name) >>
1483 Returns a boolean indicating whether or not the class defines the
1484 named method. It does not include methods inherited from parent
1487 =item B<< $metaclass->get_method_map >>
1489 Returns a hash reference representing the methods defined in this
1490 class. The keys are method names and the values are
1491 L<Class::MOP::Method> objects.
1493 =item B<< $metaclass->get_method_list >>
1495 This will return a list of method I<names> for all methods defined in
1498 =item B<< $metaclass->get_all_methods >>
1500 This will traverse the inheritance hierarchy and return a list of all
1501 the L<Class::MOP::Method> objects for this class and its parents.
1503 =item B<< $metaclass->find_method_by_name($method_name) >>
1505 This will return a L<Class::MOP::Method> for the specified
1506 C<$method_name>. If the class does not have the specified method, it
1509 Unlike C<get_method>, this method I<will> look for the named method in
1512 =item B<< $metaclass->get_all_method_names >>
1514 This will return a list of method I<names> for all of this class's
1515 methods, including inherited methods.
1517 =item B<< $metaclass->find_all_methods_by_name($method_name) >>
1519 This method looks for the named method in the class and all of its
1520 parents. It returns every matching method it finds in the inheritance
1521 tree, so it returns a list of methods.
1523 Each method is returned as a hash reference with three keys. The keys
1524 are C<name>, C<class>, and C<code>. The C<code> key has a
1525 L<Class::MOP::Method> object as its value.
1527 The list of methods is distinct.
1529 =item B<< $metaclass->find_next_method_by_name($method_name) >>
1531 This method returns the first method in any superclass matching the
1532 given name. It is effectively the method that C<SUPER::$method_name>
1535 =item B<< $metaclass->add_method($method_name, $method) >>
1537 This method takes a method name and a subroutine reference, and adds
1538 the method to the class.
1540 The subroutine reference can be a L<Class::MOP::Method>, and you are
1541 strongly encouraged to pass a meta method object instead of a code
1542 reference. If you do so, that object gets stored as part of the
1543 class's method map directly. If not, the meta information will have to
1544 be recreated later, and may be incorrect.
1546 If you provide a method object, this method will clone that object if
1547 the object's package name does not match the class name. This lets us
1548 track the original source of any methods added from other classes
1549 (notably Moose roles).
1551 =item B<< $metaclass->remove_method($method_name) >>
1553 Remove the named method from the class. This method returns the
1554 L<Class::MOP::Method> object for the method.
1556 =item B<< $metaclass->method_metaclass >>
1558 Returns the class name of the method metaclass, see
1559 L<Class::MOP::Method> for more information on the method metaclass.
1561 =item B<< $metaclass->wrapped_method_metaclass >>
1563 Returns the class name of the wrapped method metaclass, see
1564 L<Class::MOP::Method::Wrapped> for more information on the wrapped
1569 =head2 Attribute introspection and creation
1571 Because Perl 5 does not have a core concept of attributes in classes,
1572 we can only return information about attributes which have been added
1573 via this class's methods. We cannot discover information about
1574 attributes which are defined in terms of "regular" Perl 5 methods.
1578 =item B<< $metaclass->get_attribute($attribute_name) >>
1580 This will return a L<Class::MOP::Attribute> for the specified
1581 C<$attribute_name>. If the class does not have the specified
1582 attribute, it returns C<undef>
1584 =item B<< $metaclass->has_attribute($attribute_name) >>
1586 Returns a boolean indicating whether or not the class defines the
1587 named attribute. It does not include attributes inherited from parent
1590 =item B<< $metaclass->get_attribute_map >>
1592 Returns a hash reference representing the attributes defined in this
1593 class. The keys are attribute names and the values are
1594 L<Class::MOP::Attribute> objects.
1596 =item B<< $metaclass->get_attribute_list >>
1598 This will return a list of attributes I<names> for all attributes
1599 defined in this class.
1601 =item B<< $metaclass->get_all_attributes >>
1603 This will traverse the inheritance hierarchy and return a list of all
1604 the L<Class::MOP::Attribute> objects for this class and its parents.
1606 =item B<< $metaclass->find_attribute_by_name($attribute_name) >>
1608 This will return a L<Class::MOP::Attribute> for the specified
1609 C<$attribute_name>. If the class does not have the specified
1610 attribute, it returns C<undef>
1612 Unlike C<get_attribute>, this attribute I<will> look for the named
1613 attribute in superclasses.
1615 =item B<< $metaclass->add_attribute(...) >>
1617 This method accepts either an existing L<Class::MOP::Attribute>
1618 object, or parameters suitable for passing to that class's C<new>
1621 The attribute provided will be added to the class.
1623 Any accessor methods defined by the attribute will be added to the
1624 class when the attribute is added.
1626 If an attribute of the same name already exists, the old attribute
1627 will be removed first.
1629 =item B<< $metaclass->remove_attribute($attribute_name) >>
1631 This will remove the named attribute from the class, and
1632 L<Class::MOP::Attribute> object.
1634 Removing an attribute also removes any accessor methods defined by the
1637 However, note that removing an attribute will only affect I<future>
1638 object instances created for this class, not existing instances.
1640 =item B<< $metaclass->attribute_metaclass >>
1642 Returns the class name of the attribute metaclass for this class. By
1643 default, this is L<Class::MOP::Attribute>. for more information on
1647 =head2 Class Immutability
1649 Making a class immutable "freezes" the class definition. You can no
1650 longer call methods which alter the class, such as adding or removing
1651 methods or attributes.
1653 Making a class immutable lets us optimize the class by inlining some
1654 methods, and also allows us to optimize some methods on the metaclass
1657 The immutabilization system in L<Moose> takes much greater advantage
1658 of the inlining features than Class::MOP itself does.
1662 =item B<< $metaclass->make_immutable(%options) >>
1664 This method will create an immutable transformer and uses it to make
1665 the class and its metaclass object immutable.
1667 Details of how immutabilization works are in L<Class::MOP::Immutable>
1670 =item B<< $metaclass->make_mutable >>
1672 Calling this method reverse the immutabilization transformation.
1674 =item B<< $metaclass->immutable_transformer >>
1676 If the class has been made immutable previously, this returns the
1677 L<Class::MOP::Immutable> object that was created to do the
1680 If the class was never made immutable, this method will die.
1684 =head2 Method Modifiers
1686 Method modifiers are hooks which allow a method to be wrapped with
1687 I<before>, I<after> and I<around> method modifiers. Every time a
1688 method is called, it's modifiers are also called.
1690 A class can modify its own methods, as well as methods defined in
1693 =head3 How method modifiers work?
1695 Method modifiers work by wrapping the original method and then
1696 replacing it in the class's symbol table. The wrappers will handle
1697 calling all the modifiers in the appropriate order and preserving the
1698 calling context for the original method.
1700 The return values of C<before> and C<after> modifiers are
1701 ignored. This is because their purpose is B<not> to filter the input
1702 and output of the primary method (this is done with an I<around>
1705 This may seem like an odd restriction to some, but doing this allows
1706 for simple code to be added at the beginning or end of a method call
1707 without altering the function of the wrapped method or placing any
1708 extra responsibility on the code of the modifier.
1710 Of course if you have more complex needs, you can use the C<around>
1711 modifier which allows you to change both the parameters passed to the
1712 wrapped method, as well as its return value.
1714 Before and around modifiers are called in last-defined-first-called
1715 order, while after modifiers are called in first-defined-first-called
1716 order. So the call tree might looks something like this:
1728 =head3 What is the performance impact?
1730 Of course there is a performance cost associated with method
1731 modifiers, but we have made every effort to make that cost directly
1732 proportional to the number of modifier features you utilize.
1734 The wrapping method does it's best to B<only> do as much work as it
1735 absolutely needs to. In order to do this we have moved some of the
1736 performance costs to set-up time, where they are easier to amortize.
1738 All this said, our benchmarks have indicated the following:
1740 simple wrapper with no modifiers 100% slower
1741 simple wrapper with simple before modifier 400% slower
1742 simple wrapper with simple after modifier 450% slower
1743 simple wrapper with simple around modifier 500-550% slower
1744 simple wrapper with all 3 modifiers 1100% slower
1746 These numbers may seem daunting, but you must remember, every feature
1747 comes with some cost. To put things in perspective, just doing a
1748 simple C<AUTOLOAD> which does nothing but extract the name of the
1749 method called and return it costs about 400% over a normal method
1754 =item B<< $metaclass->add_before_method_modifier($method_name, $code) >>
1756 This wraps the specified method with the supplied subroutine
1757 reference. The modifier will be called as a method itself, and will
1758 receive the same arguments as are passed to the method.
1760 When the modifier exits, the wrapped method will be called.
1762 The return value of the modifier will be ignored.
1764 =item B<< $metaclass->add_after_method_modifier($method_name, $code) >>
1766 This wraps the specified method with the supplied subroutine
1767 reference. The modifier will be called as a method itself, and will
1768 receive the same arguments as are passed to the method.
1770 When the wrapped methods exits, the modifier will be called.
1772 The return value of the modifier will be ignored.
1774 =item B<< $metaclass->add_around_method_modifier($method_name, $code) >>
1776 This wraps the specified method with the supplied subroutine
1779 The first argument passed to the modifier will be a subroutine
1780 reference to the wrapped method. The second argument is the object,
1781 and after that come any arguments passed when the method is called.
1783 The around modifier can choose to call the original method, as well as
1784 what arguments to pass if it does so.
1786 The return value of the modifier is what will be seen by the caller.
1790 =head2 Introspection
1794 =item B<< Class::MOP::Class->meta >>
1796 This will return a L<Class::MOP::Class> instance for this class.
1798 It should also be noted that L<Class::MOP> will actually bootstrap
1799 this module by installing a number of attribute meta-objects into its
1806 Stevan Little E<lt>stevan@iinteractive.comE<gt>
1808 =head1 COPYRIGHT AND LICENSE
1810 Copyright 2006-2009 by Infinity Interactive, Inc.
1812 L<http://www.iinteractive.com>
1814 This library is free software; you can redistribute it and/or modify
1815 it under the same terms as Perl itself.