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;
13 use Scalar::Util 'blessed', 'reftype', 'weaken';
14 use Sub::Name 'subname';
15 use Devel::GlobalDestruction 'in_global_destruction';
17 our $VERSION = '0.95';
18 $VERSION = eval $VERSION;
19 our $AUTHORITY = 'cpan:STEVAN';
21 use base 'Class::MOP::Module', 'Class::MOP::HasAttributes';
31 $package_name = shift;
34 $package_name = $options{package};
37 ($package_name && !ref($package_name))
38 || confess "You must pass a package name and it cannot be blessed";
40 return Class::MOP::get_metaclass_by_name($package_name)
41 || $class->_construct_class_instance(package => $package_name, @_);
44 # NOTE: (meta-circularity)
45 # this is a special form of _construct_instance
46 # (see below), which is used to construct class
47 # meta-object instances for any Class::MOP::*
48 # class. All other classes will use the more
49 # normal &construct_instance.
50 sub _construct_class_instance {
52 my $options = @_ == 1 ? $_[0] : {@_};
53 my $package_name = $options->{package};
54 (defined $package_name && $package_name)
55 || confess "You must pass a package name";
57 # return the metaclass if we have it cached,
58 # and it is still defined (it has not been
59 # reaped by DESTROY yet, which can happen
60 # annoyingly enough during global destruction)
62 if (defined(my $meta = Class::MOP::get_metaclass_by_name($package_name))) {
67 # we need to deal with the possibility
68 # of class immutability here, and then
69 # get the name of the class appropriately
71 ? ($class->is_immutable
72 ? $class->_get_mutable_metaclass_name()
76 # now create the metaclass
78 if ($class eq 'Class::MOP::Class') {
79 $meta = $class->_new($options);
83 # it is safe to use meta here because
84 # class will always be a subclass of
85 # Class::MOP::Class, which defines meta
86 $meta = $class->meta->_construct_instance($options)
89 # and check the metaclass compatibility
90 $meta->_check_metaclass_compatibility();
92 Class::MOP::store_metaclass_by_name($package_name, $meta);
95 # we need to weaken any anon classes
96 # so that they can call DESTROY properly
97 Class::MOP::weaken_metaclass($package_name) if $meta->is_anon_class;
105 return Class::MOP::Class->initialize($class)->new_object(@_)
106 if $class ne __PACKAGE__;
108 my $options = @_ == 1 ? $_[0] : {@_};
111 # inherited from Class::MOP::Package
112 'package' => $options->{package},
115 # since the following attributes will
116 # actually be loaded from the symbol
117 # table, and actually bypass the instance
118 # entirely, we can just leave these things
119 # listed here for reference, because they
120 # should not actually have a value associated
122 'namespace' => \undef,
125 # inherited from Class::MOP::Module
127 'authority' => \undef,
129 # defined in Class::MOP::Class
130 'superclasses' => \undef,
133 'attribute_metaclass' =>
134 ( $options->{'attribute_metaclass'} || 'Class::MOP::Attribute' ),
135 'method_metaclass' =>
136 ( $options->{'method_metaclass'} || 'Class::MOP::Method' ),
137 'wrapped_method_metaclass' => (
138 $options->{'wrapped_method_metaclass'}
139 || 'Class::MOP::Method::Wrapped'
141 'instance_metaclass' =>
142 ( $options->{'instance_metaclass'} || 'Class::MOP::Instance' ),
143 'immutable_trait' => (
144 $options->{'immutable_trait'}
145 || 'Class::MOP::Class::Immutable::Trait'
147 'constructor_name' => ( $options->{constructor_name} || 'new' ),
148 'constructor_class' => (
149 $options->{constructor_class} || 'Class::MOP::Method::Constructor'
151 'destructor_class' => $options->{destructor_class},
155 sub reset_package_cache_flag { (shift)->{'_package_cache_flag'} = undef }
156 sub update_package_cache_flag {
159 # we can manually update the cache number
160 # since we are actually adding the method
161 # to our cache as well. This avoids us
162 # having to regenerate the method_map.
164 $self->{'_package_cache_flag'} = Class::MOP::check_package_cache_flag($self->name);
167 sub _check_metaclass_compatibility {
170 # this is always okay ...
171 return if ref($self) eq 'Class::MOP::Class' &&
172 $self->instance_metaclass eq 'Class::MOP::Instance';
174 my @class_list = $self->linearized_isa;
175 shift @class_list; # shift off $self->name
177 foreach my $superclass_name (@class_list) {
178 my $super_meta = Class::MOP::get_metaclass_by_name($superclass_name) || next;
181 # we need to deal with the possibility
182 # of class immutability here, and then
183 # get the name of the class appropriately
185 = $super_meta->is_immutable
186 ? $super_meta->_get_mutable_metaclass_name()
189 ($self->isa($super_meta_type))
190 || confess "The metaclass of " . $self->name . " ("
191 . (ref($self)) . ")" . " is not compatible with the " .
192 "metaclass of its superclass, ".$superclass_name . " ("
193 . ($super_meta_type) . ")";
195 # we also need to check that instance metaclasses
196 # are compatibile in the same the class.
197 ($self->instance_metaclass->isa($super_meta->instance_metaclass))
198 || confess "The instance metaclass for " . $self->name . " (" . ($self->instance_metaclass) . ")" .
199 " is not compatible with the " .
200 "instance metaclass of its superclass, " . $superclass_name . " (" . ($super_meta->instance_metaclass) . ")";
208 # this should be sufficient, if you have a
209 # use case where it is not, write a test and
211 my $ANON_CLASS_SERIAL = 0;
214 # we need a sufficiently annoying prefix
215 # this should suffice for now, this is
216 # used in a couple of places below, so
217 # need to put it up here for now.
218 my $ANON_CLASS_PREFIX = 'Class::MOP::Class::__ANON__::SERIAL::';
222 no warnings 'uninitialized';
223 $self->name =~ /^$ANON_CLASS_PREFIX/o;
226 sub create_anon_class {
227 my ($class, %options) = @_;
228 my $package_name = $ANON_CLASS_PREFIX . ++$ANON_CLASS_SERIAL;
229 return $class->create($package_name, %options);
233 # this will only get called for
234 # anon-classes, all other calls
235 # are assumed to occur during
236 # global destruction and so don't
237 # really need to be handled explicitly
241 return if in_global_destruction(); # it'll happen soon anyway and this just makes things more complicated
243 no warnings 'uninitialized';
244 my $name = $self->name;
245 return unless $name =~ /^$ANON_CLASS_PREFIX/o;
247 # Moose does a weird thing where it replaces the metaclass for
248 # class when fixing metaclass incompatibility. In that case,
249 # we don't want to clean out the namespace now. We can detect
250 # that because Moose will explicitly update the singleton
251 # cache in Class::MOP.
252 my $current_meta = Class::MOP::get_metaclass_by_name($name);
253 return if $current_meta ne $self;
255 my ($serial_id) = ($name =~ /^$ANON_CLASS_PREFIX(\d+)/o);
257 @{$name . '::ISA'} = ();
258 %{$name . '::'} = ();
259 delete ${$ANON_CLASS_PREFIX}{$serial_id . '::'};
261 Class::MOP::remove_metaclass_by_name($name);
266 # creating classes with MOP ...
269 my ( $class, @args ) = @_;
271 unshift @args, 'package' if @args % 2 == 1;
273 my (%options) = @args;
274 my $package_name = $options{package};
276 (ref $options{superclasses} eq 'ARRAY')
277 || confess "You must pass an ARRAY ref of superclasses"
278 if exists $options{superclasses};
280 (ref $options{attributes} eq 'ARRAY')
281 || confess "You must pass an ARRAY ref of attributes"
282 if exists $options{attributes};
284 (ref $options{methods} eq 'HASH')
285 || confess "You must pass a HASH ref of methods"
286 if exists $options{methods};
288 my (%initialize_options) = @args;
289 delete @initialize_options{qw(
297 my $meta = $class->initialize( $package_name => %initialize_options );
299 $meta->_instantiate_module( $options{version}, $options{authority} );
302 $meta->add_method('meta' => sub {
303 $class->initialize(ref($_[0]) || $_[0]);
306 $meta->superclasses(@{$options{superclasses}})
307 if exists $options{superclasses};
309 # process attributes first, so that they can
310 # install accessors, but locally defined methods
311 # can then overwrite them. It is maybe a little odd, but
312 # I think this should be the order of things.
313 if (exists $options{attributes}) {
314 foreach my $attr (@{$options{attributes}}) {
315 $meta->add_attribute($attr);
318 if (exists $options{methods}) {
319 foreach my $method_name (keys %{$options{methods}}) {
320 $meta->add_method($method_name, $options{methods}->{$method_name});
329 # all these attribute readers will be bootstrapped
330 # away in the Class::MOP bootstrap section
332 sub instance_metaclass { $_[0]->{'instance_metaclass'} }
333 sub immutable_trait { $_[0]->{'immutable_trait'} }
334 sub constructor_class { $_[0]->{'constructor_class'} }
335 sub constructor_name { $_[0]->{'constructor_name'} }
336 sub destructor_class { $_[0]->{'destructor_class'} }
338 # Instance Construction & Cloning
344 # we need to protect the integrity of the
345 # Class::MOP::Class singletons here, so we
346 # delegate this to &construct_class_instance
347 # which will deal with the singletons
348 return $class->_construct_class_instance(@_)
349 if $class->name->isa('Class::MOP::Class');
350 return $class->_construct_instance(@_);
353 sub _construct_instance {
355 my $params = @_ == 1 ? $_[0] : {@_};
356 my $meta_instance = $class->get_meta_instance();
358 # the code below is almost certainly incorrect
359 # but this is foreign inheritance, so we might
360 # have to kludge it in the end.
361 my $instance = $params->{__INSTANCE__} || $meta_instance->create_instance();
362 foreach my $attr ($class->get_all_attributes()) {
363 $attr->initialize_instance_slot($meta_instance, $instance, $params);
366 # this will only work for a HASH instance type
367 if ($class->is_anon_class) {
368 (reftype($instance) eq 'HASH')
369 || confess "Currently only HASH based instances are supported with instance of anon-classes";
371 # At some point we should make this official
372 # as a reserved slot name, but right now I am
373 # going to keep it here.
374 # my $RESERVED_MOP_SLOT = '__MOP__';
375 $instance->{'__MOP__'} = $class;
381 sub get_meta_instance {
383 $self->{'_meta_instance'} ||= $self->_create_meta_instance();
386 sub _create_meta_instance {
389 my $instance = $self->instance_metaclass->new(
390 associated_metaclass => $self,
391 attributes => [ $self->get_all_attributes() ],
394 $self->add_meta_instance_dependencies()
395 if $instance->is_dependent_on_superclasses();
402 my $instance = shift;
403 (blessed($instance) && $instance->isa($class->name))
404 || confess "You must pass an instance of the metaclass (" . (ref $class ? $class->name : $class) . "), not ($instance)";
407 # we need to protect the integrity of the
408 # Class::MOP::Class singletons here, they
409 # should not be cloned.
410 return $instance if $instance->isa('Class::MOP::Class');
411 $class->_clone_instance($instance, @_);
414 sub _clone_instance {
415 my ($class, $instance, %params) = @_;
417 || confess "You can only clone instances, ($instance) is not a blessed instance";
418 my $meta_instance = $class->get_meta_instance();
419 my $clone = $meta_instance->clone_instance($instance);
420 foreach my $attr ($class->get_all_attributes()) {
421 if ( defined( my $init_arg = $attr->init_arg ) ) {
422 if (exists $params{$init_arg}) {
423 $attr->set_value($clone, $params{$init_arg});
430 sub rebless_instance {
431 my ($self, $instance, %params) = @_;
433 my $old_metaclass = Class::MOP::class_of($instance);
435 my $old_class = $old_metaclass ? $old_metaclass->name : blessed($instance);
436 $self->name->isa($old_class)
437 || confess "You may rebless only into a subclass of ($old_class), of which (". $self->name .") isn't.";
439 $old_metaclass->rebless_instance_away($instance, $self, %params)
442 my $meta_instance = $self->get_meta_instance();
445 # we use $_[1] here because of t/306_rebless_overload.t regressions on 5.8.8
446 $meta_instance->rebless_instance_structure($_[1], $self);
448 foreach my $attr ( $self->get_all_attributes ) {
449 if ( $attr->has_value($instance) ) {
450 if ( defined( my $init_arg = $attr->init_arg ) ) {
451 $params{$init_arg} = $attr->get_value($instance)
452 unless exists $params{$init_arg};
455 $attr->set_value($instance, $attr->get_value($instance));
460 foreach my $attr ($self->get_all_attributes) {
461 $attr->initialize_instance_slot($meta_instance, $instance, \%params);
467 sub rebless_instance_away {
468 # this intentionally does nothing, it is just a hook
471 sub get_all_attributes {
473 my %attrs = map { %{ $self->initialize($_)->_attribute_map } }
474 reverse $self->linearized_isa;
475 return values %attrs;
482 my $var_spec = { sigil => '@', type => 'ARRAY', name => 'ISA' };
485 @{$self->get_package_symbol($var_spec)} = @supers;
488 # on 5.8 and below, we need to call
489 # a method to get Perl to detect
490 # a cycle in the class hierarchy
491 my $class = $self->name;
495 # we need to check the metaclass
496 # compatibility here so that we can
497 # be sure that the superclass is
498 # not potentially creating an issues
499 # we don't know about
501 $self->_check_metaclass_compatibility();
502 $self->_superclasses_updated();
504 @{$self->get_package_symbol($var_spec)};
507 sub _superclasses_updated {
509 $self->update_meta_instance_dependencies();
514 my $super_class = $self->name;
516 return @{ $super_class->mro::get_isarev() };
519 sub direct_subclasses {
521 my $super_class = $self->name;
526 } Class::MOP::Class->initialize($_)->superclasses
531 return @{ mro::get_linear_isa( (shift)->name ) };
534 sub class_precedence_list {
536 my $name = $self->name;
538 unless (Class::MOP::IS_RUNNING_ON_5_10()) {
540 # We need to check for circular inheritance here
541 # if we are are not on 5.10, cause 5.8 detects it
542 # late. This will do nothing if all is well, and
543 # blow up otherwise. Yes, it's an ugly hack, better
544 # suggestions are welcome.
546 ($name || return)->isa('This is a test for circular inheritance')
549 # if our mro is c3, we can
550 # just grab the linear_isa
551 if (mro::get_mro($name) eq 'c3') {
552 return @{ mro::get_linear_isa($name) }
556 # we can't grab the linear_isa for dfs
557 # since it has all the duplicates
562 $self->initialize($_)->class_precedence_list()
563 } $self->superclasses()
571 my $fetch_and_prepare_method = sub {
572 my ($self, $method_name) = @_;
573 my $wrapped_metaclass = $self->wrapped_method_metaclass;
575 my $method = $self->get_method($method_name);
576 # if we dont have local ...
578 # try to find the next method
579 $method = $self->find_next_method_by_name($method_name);
580 # die if it does not exist
582 || confess "The method '$method_name' was not found in the inheritance hierarchy for " . $self->name;
583 # and now make sure to wrap it
584 # even if it is already wrapped
585 # because we need a new sub ref
586 $method = $wrapped_metaclass->wrap($method,
587 package_name => $self->name,
588 name => $method_name,
592 # now make sure we wrap it properly
593 $method = $wrapped_metaclass->wrap($method,
594 package_name => $self->name,
595 name => $method_name,
596 ) unless $method->isa($wrapped_metaclass);
598 $self->add_method($method_name => $method);
602 sub add_before_method_modifier {
603 my ($self, $method_name, $method_modifier) = @_;
604 (defined $method_name && length $method_name)
605 || confess "You must pass in a method name";
606 my $method = $fetch_and_prepare_method->($self, $method_name);
607 $method->add_before_modifier(
608 subname(':before' => $method_modifier)
612 sub add_after_method_modifier {
613 my ($self, $method_name, $method_modifier) = @_;
614 (defined $method_name && length $method_name)
615 || confess "You must pass in a method name";
616 my $method = $fetch_and_prepare_method->($self, $method_name);
617 $method->add_after_modifier(
618 subname(':after' => $method_modifier)
622 sub add_around_method_modifier {
623 my ($self, $method_name, $method_modifier) = @_;
624 (defined $method_name && length $method_name)
625 || confess "You must pass in a method name";
626 my $method = $fetch_and_prepare_method->($self, $method_name);
627 $method->add_around_modifier(
628 subname(':around' => $method_modifier)
633 # the methods above used to be named like this:
634 # ${pkg}::${method}:(before|after|around)
635 # but this proved problematic when using one modifier
636 # to wrap multiple methods (something which is likely
637 # to happen pretty regularly IMO). So instead of naming
638 # it like this, I have chosen to just name them purely
639 # with their modifier names, like so:
640 # :(before|after|around)
641 # The fact is that in a stack trace, it will be fairly
642 # evident from the context what method they are attached
643 # to, and so don't need the fully qualified name.
646 sub find_method_by_name {
647 my ($self, $method_name) = @_;
648 (defined $method_name && length $method_name)
649 || confess "You must define a method name to find";
650 foreach my $class ($self->linearized_isa) {
651 my $method = $self->initialize($class)->get_method($method_name);
652 return $method if defined $method;
657 sub get_all_methods {
661 for my $class ( reverse $self->linearized_isa ) {
662 my $meta = $self->initialize($class);
664 $methods{$_} = $meta->get_method($_)
665 for $meta->get_method_list;
668 return values %methods;
671 sub get_all_method_names {
674 return grep { !$uniq{$_}++ } map { $self->initialize($_)->get_method_list } $self->linearized_isa;
677 sub find_all_methods_by_name {
678 my ($self, $method_name) = @_;
679 (defined $method_name && length $method_name)
680 || confess "You must define a method name to find";
682 foreach my $class ($self->linearized_isa) {
683 # fetch the meta-class ...
684 my $meta = $self->initialize($class);
686 name => $method_name,
688 code => $meta->get_method($method_name)
689 } if $meta->has_method($method_name);
694 sub find_next_method_by_name {
695 my ($self, $method_name) = @_;
696 (defined $method_name && length $method_name)
697 || confess "You must define a method name to find";
698 my @cpl = $self->linearized_isa;
699 shift @cpl; # discard ourselves
700 foreach my $class (@cpl) {
701 my $method = $self->initialize($class)->get_method($method_name);
702 return $method if defined $method;
707 sub update_meta_instance_dependencies {
710 if ( $self->{meta_instance_dependencies} ) {
711 return $self->add_meta_instance_dependencies;
715 sub add_meta_instance_dependencies {
718 $self->remove_meta_instance_dependencies;
720 my @attrs = $self->get_all_attributes();
723 my @classes = grep { not $seen{ $_->name }++ }
724 map { $_->associated_class } @attrs;
726 foreach my $class (@classes) {
727 $class->add_dependent_meta_instance($self);
730 $self->{meta_instance_dependencies} = \@classes;
733 sub remove_meta_instance_dependencies {
736 if ( my $classes = delete $self->{meta_instance_dependencies} ) {
737 foreach my $class (@$classes) {
738 $class->remove_dependent_meta_instance($self);
748 sub add_dependent_meta_instance {
749 my ( $self, $metaclass ) = @_;
750 push @{ $self->{dependent_meta_instances} }, $metaclass;
753 sub remove_dependent_meta_instance {
754 my ( $self, $metaclass ) = @_;
755 my $name = $metaclass->name;
756 @$_ = grep { $_->name ne $name } @$_
757 for $self->{dependent_meta_instances};
760 sub invalidate_meta_instances {
762 $_->invalidate_meta_instance()
763 for $self, @{ $self->{dependent_meta_instances} };
766 sub invalidate_meta_instance {
768 undef $self->{_meta_instance};
771 # check if we can reinitialize
775 # if any local attr is defined
776 return if $self->get_attribute_list;
778 # or any non-declared methods
779 for my $method ( map { $self->get_method($_) } $self->get_method_list ) {
780 return if $method->isa("Class::MOP::Method::Generated");
781 # FIXME do we need to enforce this too? return unless $method->isa( $self->method_metaclass );
790 sub is_immutable { 0 }
792 sub immutable_options { %{ $_[0]{__immutable}{options} || {} } }
794 sub _immutable_options {
795 my ( $self, @args ) = @_;
798 inline_accessors => 1,
799 inline_constructor => 1,
800 inline_destructor => 0,
802 immutable_trait => $self->immutable_trait,
803 constructor_name => $self->constructor_name,
804 constructor_class => $self->constructor_class,
805 destructor_class => $self->destructor_class,
811 my ( $self, @args ) = @_;
813 if ( $self->is_mutable ) {
814 $self->_initialize_immutable( $self->_immutable_options(@args) );
815 $self->_rebless_as_immutable(@args);
826 if ( $self->is_immutable ) {
827 my @args = $self->immutable_options;
828 $self->_rebless_as_mutable();
829 $self->_remove_inlined_code(@args);
830 delete $self->{__immutable};
838 sub _rebless_as_immutable {
839 my ( $self, @args ) = @_;
841 $self->{__immutable}{original_class} = ref $self;
843 bless $self => $self->_immutable_metaclass(@args);
846 sub _immutable_metaclass {
847 my ( $self, %args ) = @_;
849 if ( my $class = $args{immutable_metaclass} ) {
853 my $trait = $args{immutable_trait} = $self->immutable_trait
854 || confess "no immutable trait specified for $self";
856 my $meta = $self->meta;
857 my $meta_attr = $meta->find_attribute_by_name("immutable_trait");
861 if ( $meta_attr and $trait eq $meta_attr->default ) {
862 # if the trait is the same as the default we try and pick a
863 # predictable name for the immutable metaclass
864 $class_name = 'Class::MOP::Class::Immutable::' . ref($self);
867 $class_name = join '::', 'Class::MOP::Class::Immutable::CustomTrait',
868 $trait, 'ForMetaClass', ref($self);
872 if Class::MOP::is_class_loaded($class_name);
874 # If the metaclass is a subclass of CMOP::Class which has had
875 # metaclass roles applied (via Moose), then we want to make sure
876 # that we preserve that anonymous class (see Fey::ORM for an
877 # example of where this matters).
879 = $meta->is_immutable
880 ? $meta->_get_mutable_metaclass_name
883 my $immutable_meta = $meta_name->create(
885 superclasses => [ ref $self ],
888 Class::MOP::load_class($trait);
889 for my $meth ( Class::MOP::Class->initialize($trait)->get_all_methods ) {
890 my $meth_name = $meth->name;
892 if ( $immutable_meta->find_method_by_name( $meth_name ) ) {
893 $immutable_meta->add_around_method_modifier( $meth_name, $meth->body );
896 $immutable_meta->add_method( $meth_name, $meth->clone );
900 $immutable_meta->make_immutable(
901 inline_constructor => 0,
902 inline_accessors => 0,
908 sub _remove_inlined_code {
911 $self->remove_method( $_->name ) for $self->_inlined_methods;
913 delete $self->{__immutable}{inlined_methods};
916 sub _inlined_methods { @{ $_[0]{__immutable}{inlined_methods} || [] } }
918 sub _add_inlined_method {
919 my ( $self, $method ) = @_;
921 push @{ $self->{__immutable}{inlined_methods} ||= [] }, $method;
924 sub _initialize_immutable {
925 my ( $self, %args ) = @_;
927 $self->{__immutable}{options} = \%args;
928 $self->_install_inlined_code(%args);
931 sub _install_inlined_code {
932 my ( $self, %args ) = @_;
935 $self->_inline_accessors(%args) if $args{inline_accessors};
936 $self->_inline_constructor(%args) if $args{inline_constructor};
937 $self->_inline_destructor(%args) if $args{inline_destructor};
940 sub _rebless_as_mutable {
943 bless $self, $self->_get_mutable_metaclass_name;
948 sub _inline_accessors {
951 foreach my $attr_name ( $self->get_attribute_list ) {
952 $self->get_attribute($attr_name)->install_accessors(1);
956 sub _inline_constructor {
957 my ( $self, %args ) = @_;
959 my $name = $args{constructor_name};
960 # A class may not even have a constructor, and that's okay.
961 return unless defined $name;
963 if ( $self->has_method($name) && !$args{replace_constructor} ) {
964 my $class = $self->name;
965 warn "Not inlining a constructor for $class since it defines"
966 . " its own constructor.\n"
967 . "If you are certain you don't need to inline your"
968 . " constructor, specify inline_constructor => 0 in your"
969 . " call to $class->meta->make_immutable\n";
973 my $constructor_class = $args{constructor_class};
975 Class::MOP::load_class($constructor_class);
977 my $constructor = $constructor_class->new(
981 package_name => $self->name,
985 if ( $args{replace_constructor} or $constructor->can_be_inlined ) {
986 $self->add_method( $name => $constructor );
987 $self->_add_inlined_method($constructor);
991 sub _inline_destructor {
992 my ( $self, %args ) = @_;
994 ( exists $args{destructor_class} && defined $args{destructor_class} )
995 || confess "The 'inline_destructor' option is present, but "
996 . "no destructor class was specified";
998 if ( $self->has_method('DESTROY') && ! $args{replace_destructor} ) {
999 my $class = $self->name;
1000 warn "Not inlining a destructor for $class since it defines"
1001 . " its own destructor.\n";
1005 my $destructor_class = $args{destructor_class};
1007 Class::MOP::load_class($destructor_class);
1009 return unless $destructor_class->is_needed($self);
1011 my $destructor = $destructor_class->new(
1014 package_name => $self->name,
1018 if ( $args{replace_destructor} or $destructor->can_be_inlined ) {
1019 $self->add_method( 'DESTROY' => $destructor );
1020 $self->_add_inlined_method($destructor);
1032 Class::MOP::Class - Class Meta Object
1036 # assuming that class Foo
1037 # has been defined, you can
1039 # use this for introspection ...
1041 # add a method to Foo ...
1042 Foo->meta->add_method( 'bar' => sub {...} )
1044 # get a list of all the classes searched
1045 # the method dispatcher in the correct order
1046 Foo->meta->class_precedence_list()
1048 # remove a method from Foo
1049 Foo->meta->remove_method('bar');
1051 # or use this to actually create classes ...
1053 Class::MOP::Class->create(
1056 superclasses => ['Foo'],
1058 Class::MOP::Attribute->new('$bar'),
1059 Class::MOP::Attribute->new('$baz'),
1062 calculate_bar => sub {...},
1063 construct_baz => sub {...}
1070 The Class Protocol is the largest and most complex part of the
1071 Class::MOP meta-object protocol. It controls the introspection and
1072 manipulation of Perl 5 classes, and it can create them as well. The
1073 best way to understand what this module can do is to read the
1074 documentation for each of its methods.
1078 C<Class::MOP::Class> is a subclass of L<Class::MOP::Module>.
1082 =head2 Class construction
1084 These methods all create new C<Class::MOP::Class> objects. These
1085 objects can represent existing classes or they can be used to create
1086 new classes from scratch.
1088 The metaclass object for a given class is a singleton. If you attempt
1089 to create a metaclass for the same class twice, you will just get the
1094 =item B<< Class::MOP::Class->create($package_name, %options) >>
1096 This method creates a new C<Class::MOP::Class> object with the given
1097 package name. It accepts a number of options:
1103 An optional version number for the newly created package.
1107 An optional authority for the newly created package.
1109 =item * superclasses
1111 An optional array reference of superclass names.
1115 An optional hash reference of methods for the class. The keys of the
1116 hash reference are method names and values are subroutine references.
1120 An optional array reference of L<Class::MOP::Attribute> objects.
1124 =item B<< Class::MOP::Class->create_anon_class(%options) >>
1126 This method works just like C<< Class::MOP::Class->create >> but it
1127 creates an "anonymous" class. In fact, the class does have a name, but
1128 that name is a unique name generated internally by this module.
1130 It accepts the same C<superclasses>, C<methods>, and C<attributes>
1131 parameters that C<create> accepts.
1133 Anonymous classes are destroyed once the metaclass they are attached
1134 to goes out of scope, and will be removed from Perl's internal symbol
1137 All instances of an anonymous class keep a special reference to the
1138 metaclass object, which prevents the metaclass from going out of scope
1139 while any instances exist.
1141 This only works if the instance is based on a hash reference, however.
1143 =item B<< Class::MOP::Class->initialize($package_name, %options) >>
1145 This method will initialize a C<Class::MOP::Class> object for the
1146 named package. Unlike C<create>, this method I<will not> create a new
1149 The purpose of this method is to retrieve a C<Class::MOP::Class>
1150 object for introspecting an existing class.
1152 If an existing C<Class::MOP::Class> object exists for the named
1153 package, it will be returned, and any options provided will be
1156 If the object does not yet exist, it will be created.
1158 The valid options that can be passed to this method are
1159 C<attribute_metaclass>, C<method_metaclass>,
1160 C<wrapped_method_metaclass>, and C<instance_metaclass>. These are all
1161 optional, and default to the appropriate class in the C<Class::MOP>
1166 =head2 Object instance construction and cloning
1168 These methods are all related to creating and/or cloning object
1173 =item B<< $metaclass->clone_object($instance, %params) >>
1175 This method clones an existing object instance. Any parameters you
1176 provide are will override existing attribute values in the object.
1178 This is a convenience method for cloning an object instance, then
1179 blessing it into the appropriate package.
1181 You could implement a clone method in your class, using this method:
1184 my ($self, %params) = @_;
1185 $self->meta->clone_object($self, %params);
1188 =item B<< $metaclass->rebless_instance($instance, %params) >>
1190 This method changes the class of C<$instance> to the metaclass's class.
1192 You can only rebless an instance into a subclass of its current
1193 class. If you pass any additional parameters, these will be treated
1194 like constructor parameters and used to initialize the object's
1195 attributes. Any existing attributes that are already set will be
1198 Before reblessing the instance, this method will call
1199 C<rebless_instance_away> on the instance's current metaclass. This method
1200 will be passed the instance, the new metaclass, and any parameters
1201 specified to C<rebless_instance>. By default, C<rebless_instance_away>
1202 does nothing; it is merely a hook.
1204 =item B<< $metaclass->new_object(%params) >>
1206 This method is used to create a new object of the metaclass's
1207 class. Any parameters you provide are used to initialize the
1208 instance's attributes. A special C<__INSTANCE__> key can be passed to
1209 provide an already generated instance, rather than having Class::MOP
1210 generate it for you. This is mostly useful for using Class::MOP with
1211 foreign classes which generate instances using their own constructors.
1213 =item B<< $metaclass->instance_metaclass >>
1215 Returns the class name of the instance metaclass. See
1216 L<Class::MOP::Instance> for more information on the instance
1219 =item B<< $metaclass->get_meta_instance >>
1221 Returns an instance of the C<instance_metaclass> to be used in the
1222 construction of a new instance of the class.
1226 =head2 Informational predicates
1228 These are a few predicate methods for asking information about the
1233 =item B<< $metaclass->is_anon_class >>
1235 This returns true if the class was created by calling C<<
1236 Class::MOP::Class->create_anon_class >>.
1238 =item B<< $metaclass->is_mutable >>
1240 This returns true if the class is still mutable.
1242 =item B<< $metaclass->is_immutable >>
1244 This returns true if the class has been made immutable.
1246 =item B<< $metaclass->is_pristine >>
1248 A class is I<not> pristine if it has non-inherited attributes or if it
1249 has any generated methods.
1253 =head2 Inheritance Relationships
1257 =item B<< $metaclass->superclasses(@superclasses) >>
1259 This is a read-write accessor which represents the superclass
1260 relationships of the metaclass's class.
1262 This is basically sugar around getting and setting C<@ISA>.
1264 =item B<< $metaclass->class_precedence_list >>
1266 This returns a list of all of the class's ancestor classes. The
1267 classes are returned in method dispatch order.
1269 =item B<< $metaclass->linearized_isa >>
1271 This returns a list based on C<class_precedence_list> but with all
1274 =item B<< $metaclass->subclasses >>
1276 This returns a list of all subclasses for this class, even indirect
1279 =item B<< $metaclass->direct_subclasses >>
1281 This returns a list of immediate subclasses for this class, which does not
1282 include indirect subclasses.
1286 =head2 Method introspection
1288 See L<Class::MOP::Package/Method introspection and creation> for
1289 methods that operate only on the current class. Class::MOP::Class adds
1290 introspection capabilities that take inheritance into account.
1294 =item B<< $metaclass->get_all_methods >>
1296 This will traverse the inheritance hierarchy and return a list of all
1297 the L<Class::MOP::Method> objects for this class and its parents.
1299 =item B<< $metaclass->find_method_by_name($method_name) >>
1301 This will return a L<Class::MOP::Method> for the specified
1302 C<$method_name>. If the class does not have the specified method, it
1305 Unlike C<get_method>, this method I<will> look for the named method in
1308 =item B<< $metaclass->get_all_method_names >>
1310 This will return a list of method I<names> for all of this class's
1311 methods, including inherited methods.
1313 =item B<< $metaclass->find_all_methods_by_name($method_name) >>
1315 This method looks for the named method in the class and all of its
1316 parents. It returns every matching method it finds in the inheritance
1317 tree, so it returns a list of methods.
1319 Each method is returned as a hash reference with three keys. The keys
1320 are C<name>, C<class>, and C<code>. The C<code> key has a
1321 L<Class::MOP::Method> object as its value.
1323 The list of methods is distinct.
1325 =item B<< $metaclass->find_next_method_by_name($method_name) >>
1327 This method returns the first method in any superclass matching the
1328 given name. It is effectively the method that C<SUPER::$method_name>
1333 =head2 Attribute introspection and creation
1335 Because Perl 5 does not have a core concept of attributes in classes,
1336 we can only return information about attributes which have been added
1337 via this class's methods. We cannot discover information about
1338 attributes which are defined in terms of "regular" Perl 5 methods.
1342 =item B<< $metaclass->get_attribute($attribute_name) >>
1344 This will return a L<Class::MOP::Attribute> for the specified
1345 C<$attribute_name>. If the class does not have the specified
1346 attribute, it returns C<undef>.
1348 NOTE that get_attribute does not search superclasses, for that you
1349 need to use C<find_attribute_by_name>.
1351 =item B<< $metaclass->has_attribute($attribute_name) >>
1353 Returns a boolean indicating whether or not the class defines the
1354 named attribute. It does not include attributes inherited from parent
1357 =item B<< $metaclass->get_attribute_list >>
1359 This will return a list of attributes I<names> for all attributes
1360 defined in this class.
1362 =item B<< $metaclass->get_all_attributes >>
1364 This will traverse the inheritance hierarchy and return a list of all
1365 the L<Class::MOP::Attribute> objects for this class and its parents.
1367 =item B<< $metaclass->find_attribute_by_name($attribute_name) >>
1369 This will return a L<Class::MOP::Attribute> for the specified
1370 C<$attribute_name>. If the class does not have the specified
1371 attribute, it returns C<undef>.
1373 Unlike C<get_attribute>, this attribute I<will> look for the named
1374 attribute in superclasses.
1376 =item B<< $metaclass->add_attribute(...) >>
1378 This method accepts either an existing L<Class::MOP::Attribute>
1379 object or parameters suitable for passing to that class's C<new>
1382 The attribute provided will be added to the class.
1384 Any accessor methods defined by the attribute will be added to the
1385 class when the attribute is added.
1387 If an attribute of the same name already exists, the old attribute
1388 will be removed first.
1390 =item B<< $metaclass->remove_attribute($attribute_name) >>
1392 This will remove the named attribute from the class, and
1393 L<Class::MOP::Attribute> object.
1395 Removing an attribute also removes any accessor methods defined by the
1398 However, note that removing an attribute will only affect I<future>
1399 object instances created for this class, not existing instances.
1401 =item B<< $metaclass->attribute_metaclass >>
1403 Returns the class name of the attribute metaclass for this class. By
1404 default, this is L<Class::MOP::Attribute>.
1408 =head2 Class Immutability
1410 Making a class immutable "freezes" the class definition. You can no
1411 longer call methods which alter the class, such as adding or removing
1412 methods or attributes.
1414 Making a class immutable lets us optimize the class by inlining some
1415 methods, and also allows us to optimize some methods on the metaclass
1418 After immutabilization, the metaclass object will cache most informational
1419 methods that returns information about methods or attributes. Methods which
1420 would alter the class, such as C<add_attribute> and C<add_method>, will
1421 throw an error on an immutable metaclass object.
1423 The immutabilization system in L<Moose> takes much greater advantage
1424 of the inlining features than Class::MOP itself does.
1428 =item B<< $metaclass->make_immutable(%options) >>
1430 This method will create an immutable transformer and use it to make
1431 the class and its metaclass object immutable.
1433 This method accepts the following options:
1437 =item * inline_accessors
1439 =item * inline_constructor
1441 =item * inline_destructor
1443 These are all booleans indicating whether the specified method(s)
1446 By default, accessors and the constructor are inlined, but not the
1449 =item * immutable_trait
1451 The name of a class which will be used as a parent class for the
1452 metaclass object being made immutable. This "trait" implements the
1453 post-immutability functionality of the metaclass (but not the
1454 transformation itself).
1456 This defaults to L<Class::MOP::Class::Immutable::Trait>.
1458 =item * constructor_name
1460 This is the constructor method name. This defaults to "new".
1462 =item * constructor_class
1464 The name of the method metaclass for constructors. It will be used to
1465 generate the inlined constructor. This defaults to
1466 "Class::MOP::Method::Constructor".
1468 =item * replace_constructor
1470 This is a boolean indicating whether an existing constructor should be
1471 replaced when inlining a constructor. This defaults to false.
1473 =item * destructor_class
1475 The name of the method metaclass for destructors. It will be used to
1476 generate the inlined destructor. This defaults to
1477 "Class::MOP::Method::Denstructor".
1479 =item * replace_destructor
1481 This is a boolean indicating whether an existing destructor should be
1482 replaced when inlining a destructor. This defaults to false.
1486 =item B<< $metaclass->immutable_options >>
1488 Returns a hash of the options used when making the class immutable, including
1489 both defaults and anything supplied by the user in the call to C<<
1490 $metaclass->make_immutable >>. This is useful if you need to temporarily make
1491 a class mutable and then restore immutability as it was before.
1493 =item B<< $metaclass->make_mutable >>
1495 Calling this method reverse the immutabilization transformation.
1499 =head2 Method Modifiers
1501 Method modifiers are hooks which allow a method to be wrapped with
1502 I<before>, I<after> and I<around> method modifiers. Every time a
1503 method is called, its modifiers are also called.
1505 A class can modify its own methods, as well as methods defined in
1508 =head3 How method modifiers work?
1510 Method modifiers work by wrapping the original method and then
1511 replacing it in the class's symbol table. The wrappers will handle
1512 calling all the modifiers in the appropriate order and preserving the
1513 calling context for the original method.
1515 The return values of C<before> and C<after> modifiers are
1516 ignored. This is because their purpose is B<not> to filter the input
1517 and output of the primary method (this is done with an I<around>
1520 This may seem like an odd restriction to some, but doing this allows
1521 for simple code to be added at the beginning or end of a method call
1522 without altering the function of the wrapped method or placing any
1523 extra responsibility on the code of the modifier.
1525 Of course if you have more complex needs, you can use the C<around>
1526 modifier which allows you to change both the parameters passed to the
1527 wrapped method, as well as its return value.
1529 Before and around modifiers are called in last-defined-first-called
1530 order, while after modifiers are called in first-defined-first-called
1531 order. So the call tree might looks something like this:
1543 =head3 What is the performance impact?
1545 Of course there is a performance cost associated with method
1546 modifiers, but we have made every effort to make that cost directly
1547 proportional to the number of modifier features you use.
1549 The wrapping method does its best to B<only> do as much work as it
1550 absolutely needs to. In order to do this we have moved some of the
1551 performance costs to set-up time, where they are easier to amortize.
1553 All this said, our benchmarks have indicated the following:
1555 simple wrapper with no modifiers 100% slower
1556 simple wrapper with simple before modifier 400% slower
1557 simple wrapper with simple after modifier 450% slower
1558 simple wrapper with simple around modifier 500-550% slower
1559 simple wrapper with all 3 modifiers 1100% slower
1561 These numbers may seem daunting, but you must remember, every feature
1562 comes with some cost. To put things in perspective, just doing a
1563 simple C<AUTOLOAD> which does nothing but extract the name of the
1564 method called and return it costs about 400% over a normal method
1569 =item B<< $metaclass->add_before_method_modifier($method_name, $code) >>
1571 This wraps the specified method with the supplied subroutine
1572 reference. The modifier will be called as a method itself, and will
1573 receive the same arguments as are passed to the method.
1575 When the modifier exits, the wrapped method will be called.
1577 The return value of the modifier will be ignored.
1579 =item B<< $metaclass->add_after_method_modifier($method_name, $code) >>
1581 This wraps the specified method with the supplied subroutine
1582 reference. The modifier will be called as a method itself, and will
1583 receive the same arguments as are passed to the method.
1585 When the wrapped methods exits, the modifier will be called.
1587 The return value of the modifier will be ignored.
1589 =item B<< $metaclass->add_around_method_modifier($method_name, $code) >>
1591 This wraps the specified method with the supplied subroutine
1594 The first argument passed to the modifier will be a subroutine
1595 reference to the wrapped method. The second argument is the object,
1596 and after that come any arguments passed when the method is called.
1598 The around modifier can choose to call the original method, as well as
1599 what arguments to pass if it does so.
1601 The return value of the modifier is what will be seen by the caller.
1605 =head2 Introspection
1609 =item B<< Class::MOP::Class->meta >>
1611 This will return a L<Class::MOP::Class> instance for this class.
1613 It should also be noted that L<Class::MOP> will actually bootstrap
1614 this module by installing a number of attribute meta-objects into its
1621 Stevan Little E<lt>stevan@iinteractive.comE<gt>
1623 =head1 COPYRIGHT AND LICENSE
1625 Copyright 2006-2009 by Infinity Interactive, Inc.
1627 L<http://www.iinteractive.com>
1629 This library is free software; you can redistribute it and/or modify
1630 it under the same terms as Perl itself.