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';
18 our $VERSION = '0.97';
19 $VERSION = eval $VERSION;
20 our $AUTHORITY = 'cpan:STEVAN';
22 use base 'Class::MOP::Module', 'Class::MOP::HasAttributes';
32 $package_name = shift;
35 $package_name = $options{package};
38 ($package_name && !ref($package_name))
39 || confess "You must pass a package name and it cannot be blessed";
41 return Class::MOP::get_metaclass_by_name($package_name)
42 || $class->_construct_class_instance(package => $package_name, @_);
45 # NOTE: (meta-circularity)
46 # this is a special form of _construct_instance
47 # (see below), which is used to construct class
48 # meta-object instances for any Class::MOP::*
49 # class. All other classes will use the more
50 # normal &construct_instance.
51 sub _construct_class_instance {
53 my $options = @_ == 1 ? $_[0] : {@_};
54 my $package_name = $options->{package};
55 (defined $package_name && $package_name)
56 || confess "You must pass a package name";
58 # return the metaclass if we have it cached,
59 # and it is still defined (it has not been
60 # reaped by DESTROY yet, which can happen
61 # annoyingly enough during global destruction)
63 if (defined(my $meta = Class::MOP::get_metaclass_by_name($package_name))) {
68 # we need to deal with the possibility
69 # of class immutability here, and then
70 # get the name of the class appropriately
72 ? ($class->is_immutable
73 ? $class->_get_mutable_metaclass_name()
77 # now create the metaclass
79 if ($class eq 'Class::MOP::Class') {
80 $meta = $class->_new($options);
84 # it is safe to use meta here because
85 # class will always be a subclass of
86 # Class::MOP::Class, which defines meta
87 $meta = $class->meta->_construct_instance($options)
90 # and check the metaclass compatibility
91 $meta->_check_metaclass_compatibility();
93 Class::MOP::store_metaclass_by_name($package_name, $meta);
96 # we need to weaken any anon classes
97 # so that they can call DESTROY properly
98 Class::MOP::weaken_metaclass($package_name) if $meta->is_anon_class;
106 return Class::MOP::Class->initialize($class)->new_object(@_)
107 if $class ne __PACKAGE__;
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,
126 # inherited from Class::MOP::Module
128 'authority' => \undef,
130 # defined in Class::MOP::Class
131 '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);
168 sub _check_metaclass_compatibility {
171 # this is always okay ...
172 return if ref($self) eq 'Class::MOP::Class' &&
173 $self->instance_metaclass eq 'Class::MOP::Instance';
175 my @class_list = $self->linearized_isa;
176 shift @class_list; # shift off $self->name
178 foreach my $superclass_name (@class_list) {
179 my $super_meta = Class::MOP::get_metaclass_by_name($superclass_name) || next;
182 # we need to deal with the possibility
183 # of class immutability here, and then
184 # get the name of the class appropriately
186 = $super_meta->is_immutable
187 ? $super_meta->_get_mutable_metaclass_name()
190 ($self->isa($super_meta_type))
191 || confess "The metaclass of " . $self->name . " ("
192 . (ref($self)) . ")" . " is not compatible with the " .
193 "metaclass of its superclass, ".$superclass_name . " ("
194 . ($super_meta_type) . ")";
196 # we also need to check that instance metaclasses
197 # are compatibile in the same the class.
198 ($self->instance_metaclass->isa($super_meta->instance_metaclass))
199 || confess "The instance metaclass for " . $self->name . " (" . ($self->instance_metaclass) . ")" .
200 " is not compatible with the " .
201 "instance metaclass of its superclass, " . $superclass_name . " (" . ($super_meta->instance_metaclass) . ")";
209 # this should be sufficient, if you have a
210 # use case where it is not, write a test and
212 my $ANON_CLASS_SERIAL = 0;
215 # we need a sufficiently annoying prefix
216 # this should suffice for now, this is
217 # used in a couple of places below, so
218 # need to put it up here for now.
219 my $ANON_CLASS_PREFIX = 'Class::MOP::Class::__ANON__::SERIAL::';
223 no warnings 'uninitialized';
224 $self->name =~ /^$ANON_CLASS_PREFIX/o;
227 sub create_anon_class {
228 my ($class, %options) = @_;
229 my $package_name = $ANON_CLASS_PREFIX . ++$ANON_CLASS_SERIAL;
230 return $class->create($package_name, %options);
234 # this will only get called for
235 # anon-classes, all other calls
236 # are assumed to occur during
237 # global destruction and so don't
238 # really need to be handled explicitly
242 return if in_global_destruction(); # it'll happen soon anyway and this just makes things more complicated
244 no warnings 'uninitialized';
245 my $name = $self->name;
246 return unless $name =~ /^$ANON_CLASS_PREFIX/o;
248 # Moose does a weird thing where it replaces the metaclass for
249 # class when fixing metaclass incompatibility. In that case,
250 # we don't want to clean out the namespace now. We can detect
251 # that because Moose will explicitly update the singleton
252 # cache in Class::MOP.
253 my $current_meta = Class::MOP::get_metaclass_by_name($name);
254 return if $current_meta ne $self;
256 my ($serial_id) = ($name =~ /^$ANON_CLASS_PREFIX(\d+)/o);
258 @{$name . '::ISA'} = ();
259 %{$name . '::'} = ();
260 delete ${$ANON_CLASS_PREFIX}{$serial_id . '::'};
262 Class::MOP::remove_metaclass_by_name($name);
267 # creating classes with MOP ...
270 my ( $class, @args ) = @_;
272 unshift @args, 'package' if @args % 2 == 1;
274 my (%options) = @args;
275 my $package_name = $options{package};
277 (ref $options{superclasses} eq 'ARRAY')
278 || confess "You must pass an ARRAY ref of superclasses"
279 if exists $options{superclasses};
281 (ref $options{attributes} eq 'ARRAY')
282 || confess "You must pass an ARRAY ref of attributes"
283 if exists $options{attributes};
285 (ref $options{methods} eq 'HASH')
286 || confess "You must pass a HASH ref of methods"
287 if exists $options{methods};
289 my (%initialize_options) = @args;
290 delete @initialize_options{qw(
298 my $meta = $class->initialize( $package_name => %initialize_options );
300 $meta->_instantiate_module( $options{version}, $options{authority} );
303 $meta->add_method('meta' => sub {
304 $class->initialize(ref($_[0]) || $_[0]);
307 $meta->superclasses(@{$options{superclasses}})
308 if exists $options{superclasses};
310 # process attributes first, so that they can
311 # install accessors, but locally defined methods
312 # can then overwrite them. It is maybe a little odd, but
313 # I think this should be the order of things.
314 if (exists $options{attributes}) {
315 foreach my $attr (@{$options{attributes}}) {
316 $meta->add_attribute($attr);
319 if (exists $options{methods}) {
320 foreach my $method_name (keys %{$options{methods}}) {
321 $meta->add_method($method_name, $options{methods}->{$method_name});
330 # all these attribute readers will be bootstrapped
331 # away in the Class::MOP bootstrap section
333 sub instance_metaclass { $_[0]->{'instance_metaclass'} }
334 sub immutable_trait { $_[0]->{'immutable_trait'} }
335 sub constructor_class { $_[0]->{'constructor_class'} }
336 sub constructor_name { $_[0]->{'constructor_name'} }
337 sub destructor_class { $_[0]->{'destructor_class'} }
339 # Instance Construction & Cloning
345 # we need to protect the integrity of the
346 # Class::MOP::Class singletons here, so we
347 # delegate this to &construct_class_instance
348 # which will deal with the singletons
349 return $class->_construct_class_instance(@_)
350 if $class->name->isa('Class::MOP::Class');
351 return $class->_construct_instance(@_);
354 sub _construct_instance {
356 my $params = @_ == 1 ? $_[0] : {@_};
357 my $meta_instance = $class->get_meta_instance();
359 # the code below is almost certainly incorrect
360 # but this is foreign inheritance, so we might
361 # have to kludge it in the end.
362 my $instance = $params->{__INSTANCE__} || $meta_instance->create_instance();
363 foreach my $attr ($class->get_all_attributes()) {
364 $attr->initialize_instance_slot($meta_instance, $instance, $params);
367 # this will only work for a HASH instance type
368 if ($class->is_anon_class) {
369 (reftype($instance) eq 'HASH')
370 || confess "Currently only HASH based instances are supported with instance of anon-classes";
372 # At some point we should make this official
373 # as a reserved slot name, but right now I am
374 # going to keep it here.
375 # my $RESERVED_MOP_SLOT = '__MOP__';
376 $instance->{'__MOP__'} = $class;
382 sub get_meta_instance {
384 $self->{'_meta_instance'} ||= $self->_create_meta_instance();
387 sub _create_meta_instance {
390 my $instance = $self->instance_metaclass->new(
391 associated_metaclass => $self,
392 attributes => [ $self->get_all_attributes() ],
395 $self->add_meta_instance_dependencies()
396 if $instance->is_dependent_on_superclasses();
403 my $instance = shift;
404 (blessed($instance) && $instance->isa($class->name))
405 || confess "You must pass an instance of the metaclass (" . (ref $class ? $class->name : $class) . "), not ($instance)";
408 # we need to protect the integrity of the
409 # Class::MOP::Class singletons here, they
410 # should not be cloned.
411 return $instance if $instance->isa('Class::MOP::Class');
412 $class->_clone_instance($instance, @_);
415 sub _clone_instance {
416 my ($class, $instance, %params) = @_;
418 || confess "You can only clone instances, ($instance) is not a blessed instance";
419 my $meta_instance = $class->get_meta_instance();
420 my $clone = $meta_instance->clone_instance($instance);
421 foreach my $attr ($class->get_all_attributes()) {
422 if ( defined( my $init_arg = $attr->init_arg ) ) {
423 if (exists $params{$init_arg}) {
424 $attr->set_value($clone, $params{$init_arg});
431 sub rebless_instance {
432 my ($self, $instance, %params) = @_;
434 my $old_metaclass = Class::MOP::class_of($instance);
436 my $old_class = $old_metaclass ? $old_metaclass->name : blessed($instance);
437 $self->name->isa($old_class)
438 || confess "You may rebless only into a subclass of ($old_class), of which (". $self->name .") isn't.";
440 $old_metaclass->rebless_instance_away($instance, $self, %params)
443 my $meta_instance = $self->get_meta_instance();
446 # we use $_[1] here because of t/306_rebless_overload.t regressions on 5.8.8
447 $meta_instance->rebless_instance_structure($_[1], $self);
449 foreach my $attr ( $self->get_all_attributes ) {
450 if ( $attr->has_value($instance) ) {
451 if ( defined( my $init_arg = $attr->init_arg ) ) {
452 $params{$init_arg} = $attr->get_value($instance)
453 unless exists $params{$init_arg};
456 $attr->set_value($instance, $attr->get_value($instance));
461 foreach my $attr ($self->get_all_attributes) {
462 $attr->initialize_instance_slot($meta_instance, $instance, \%params);
468 sub rebless_instance_away {
469 # this intentionally does nothing, it is just a hook
472 sub _attach_attribute {
473 my ($self, $attribute) = @_;
474 $attribute->attach_to_class($self);
477 sub _post_add_attribute {
478 my ( $self, $attribute ) = @_;
480 $self->invalidate_meta_instances;
482 # invalidate package flag here
485 $attribute->install_accessors;
488 $self->remove_attribute( $attribute->name );
493 sub remove_attribute {
496 my $removed_attribute = $self->SUPER::remove_attribute(@_)
499 $self->invalidate_meta_instances;
501 $removed_attribute->remove_accessors;
502 $removed_attribute->detach_from_class;
504 return$removed_attribute;
507 sub find_attribute_by_name {
508 my ( $self, $attr_name ) = @_;
510 foreach my $class ( $self->linearized_isa ) {
511 # fetch the meta-class ...
512 my $meta = $self->initialize($class);
513 return $meta->get_attribute($attr_name)
514 if $meta->has_attribute($attr_name);
520 sub get_all_attributes {
522 my %attrs = map { %{ $self->initialize($_)->_attribute_map } }
523 reverse $self->linearized_isa;
524 return values %attrs;
531 my $var_spec = { sigil => '@', type => 'ARRAY', name => 'ISA' };
534 @{$self->get_package_symbol($var_spec)} = @supers;
537 # on 5.8 and below, we need to call
538 # a method to get Perl to detect
539 # a cycle in the class hierarchy
540 my $class = $self->name;
544 # we need to check the metaclass
545 # compatibility here so that we can
546 # be sure that the superclass is
547 # not potentially creating an issues
548 # we don't know about
550 $self->_check_metaclass_compatibility();
551 $self->_superclasses_updated();
553 @{$self->get_package_symbol($var_spec)};
556 sub _superclasses_updated {
558 $self->update_meta_instance_dependencies();
563 my $super_class = $self->name;
565 return @{ $super_class->mro::get_isarev() };
568 sub direct_subclasses {
570 my $super_class = $self->name;
575 } Class::MOP::Class->initialize($_)->superclasses
580 return @{ mro::get_linear_isa( (shift)->name ) };
583 sub class_precedence_list {
585 my $name = $self->name;
587 unless (Class::MOP::IS_RUNNING_ON_5_10()) {
589 # We need to check for circular inheritance here
590 # if we are are not on 5.10, cause 5.8 detects it
591 # late. This will do nothing if all is well, and
592 # blow up otherwise. Yes, it's an ugly hack, better
593 # suggestions are welcome.
595 ($name || return)->isa('This is a test for circular inheritance')
598 # if our mro is c3, we can
599 # just grab the linear_isa
600 if (mro::get_mro($name) eq 'c3') {
601 return @{ mro::get_linear_isa($name) }
605 # we can't grab the linear_isa for dfs
606 # since it has all the duplicates
611 $self->initialize($_)->class_precedence_list()
612 } $self->superclasses()
620 my $fetch_and_prepare_method = sub {
621 my ($self, $method_name) = @_;
622 my $wrapped_metaclass = $self->wrapped_method_metaclass;
624 my $method = $self->get_method($method_name);
625 # if we dont have local ...
627 # try to find the next method
628 $method = $self->find_next_method_by_name($method_name);
629 # die if it does not exist
631 || confess "The method '$method_name' was not found in the inheritance hierarchy for " . $self->name;
632 # and now make sure to wrap it
633 # even if it is already wrapped
634 # because we need a new sub ref
635 $method = $wrapped_metaclass->wrap($method,
636 package_name => $self->name,
637 name => $method_name,
641 # now make sure we wrap it properly
642 $method = $wrapped_metaclass->wrap($method,
643 package_name => $self->name,
644 name => $method_name,
645 ) unless $method->isa($wrapped_metaclass);
647 $self->add_method($method_name => $method);
651 sub add_before_method_modifier {
652 my ($self, $method_name, $method_modifier) = @_;
653 (defined $method_name && length $method_name)
654 || confess "You must pass in a method name";
655 my $method = $fetch_and_prepare_method->($self, $method_name);
656 $method->add_before_modifier(
657 subname(':before' => $method_modifier)
661 sub add_after_method_modifier {
662 my ($self, $method_name, $method_modifier) = @_;
663 (defined $method_name && length $method_name)
664 || confess "You must pass in a method name";
665 my $method = $fetch_and_prepare_method->($self, $method_name);
666 $method->add_after_modifier(
667 subname(':after' => $method_modifier)
671 sub add_around_method_modifier {
672 my ($self, $method_name, $method_modifier) = @_;
673 (defined $method_name && length $method_name)
674 || confess "You must pass in a method name";
675 my $method = $fetch_and_prepare_method->($self, $method_name);
676 $method->add_around_modifier(
677 subname(':around' => $method_modifier)
682 # the methods above used to be named like this:
683 # ${pkg}::${method}:(before|after|around)
684 # but this proved problematic when using one modifier
685 # to wrap multiple methods (something which is likely
686 # to happen pretty regularly IMO). So instead of naming
687 # it like this, I have chosen to just name them purely
688 # with their modifier names, like so:
689 # :(before|after|around)
690 # The fact is that in a stack trace, it will be fairly
691 # evident from the context what method they are attached
692 # to, and so don't need the fully qualified name.
695 sub find_method_by_name {
696 my ($self, $method_name) = @_;
697 (defined $method_name && length $method_name)
698 || confess "You must define a method name to find";
699 foreach my $class ($self->linearized_isa) {
700 my $method = $self->initialize($class)->get_method($method_name);
701 return $method if defined $method;
706 sub get_all_methods {
710 for my $class ( reverse $self->linearized_isa ) {
711 my $meta = $self->initialize($class);
713 $methods{$_} = $meta->get_method($_)
714 for $meta->get_method_list;
717 return values %methods;
720 sub get_all_method_names {
723 return grep { !$uniq{$_}++ } map { $self->initialize($_)->get_method_list } $self->linearized_isa;
726 sub find_all_methods_by_name {
727 my ($self, $method_name) = @_;
728 (defined $method_name && length $method_name)
729 || confess "You must define a method name to find";
731 foreach my $class ($self->linearized_isa) {
732 # fetch the meta-class ...
733 my $meta = $self->initialize($class);
735 name => $method_name,
737 code => $meta->get_method($method_name)
738 } if $meta->has_method($method_name);
743 sub find_next_method_by_name {
744 my ($self, $method_name) = @_;
745 (defined $method_name && length $method_name)
746 || confess "You must define a method name to find";
747 my @cpl = $self->linearized_isa;
748 shift @cpl; # discard ourselves
749 foreach my $class (@cpl) {
750 my $method = $self->initialize($class)->get_method($method_name);
751 return $method if defined $method;
756 sub update_meta_instance_dependencies {
759 if ( $self->{meta_instance_dependencies} ) {
760 return $self->add_meta_instance_dependencies;
764 sub add_meta_instance_dependencies {
767 $self->remove_meta_instance_dependencies;
769 my @attrs = $self->get_all_attributes();
772 my @classes = grep { not $seen{ $_->name }++ }
773 map { $_->associated_class } @attrs;
775 foreach my $class (@classes) {
776 $class->add_dependent_meta_instance($self);
779 $self->{meta_instance_dependencies} = \@classes;
782 sub remove_meta_instance_dependencies {
785 if ( my $classes = delete $self->{meta_instance_dependencies} ) {
786 foreach my $class (@$classes) {
787 $class->remove_dependent_meta_instance($self);
797 sub add_dependent_meta_instance {
798 my ( $self, $metaclass ) = @_;
799 push @{ $self->{dependent_meta_instances} }, $metaclass;
802 sub remove_dependent_meta_instance {
803 my ( $self, $metaclass ) = @_;
804 my $name = $metaclass->name;
805 @$_ = grep { $_->name ne $name } @$_
806 for $self->{dependent_meta_instances};
809 sub invalidate_meta_instances {
811 $_->invalidate_meta_instance()
812 for $self, @{ $self->{dependent_meta_instances} };
815 sub invalidate_meta_instance {
817 undef $self->{_meta_instance};
820 # check if we can reinitialize
824 # if any local attr is defined
825 return if $self->get_attribute_list;
827 # or any non-declared methods
828 for my $method ( map { $self->get_method($_) } $self->get_method_list ) {
829 return if $method->isa("Class::MOP::Method::Generated");
830 # FIXME do we need to enforce this too? return unless $method->isa( $self->method_metaclass );
839 sub is_immutable { 0 }
841 sub immutable_options { %{ $_[0]{__immutable}{options} || {} } }
843 sub _immutable_options {
844 my ( $self, @args ) = @_;
847 inline_accessors => 1,
848 inline_constructor => 1,
849 inline_destructor => 0,
851 immutable_trait => $self->immutable_trait,
852 constructor_name => $self->constructor_name,
853 constructor_class => $self->constructor_class,
854 destructor_class => $self->destructor_class,
860 my ( $self, @args ) = @_;
862 if ( $self->is_mutable ) {
863 $self->_initialize_immutable( $self->_immutable_options(@args) );
864 $self->_rebless_as_immutable(@args);
875 if ( $self->is_immutable ) {
876 my @args = $self->immutable_options;
877 $self->_rebless_as_mutable();
878 $self->_remove_inlined_code(@args);
879 delete $self->{__immutable};
887 sub _rebless_as_immutable {
888 my ( $self, @args ) = @_;
890 $self->{__immutable}{original_class} = ref $self;
892 bless $self => $self->_immutable_metaclass(@args);
895 sub _immutable_metaclass {
896 my ( $self, %args ) = @_;
898 if ( my $class = $args{immutable_metaclass} ) {
902 my $trait = $args{immutable_trait} = $self->immutable_trait
903 || confess "no immutable trait specified for $self";
905 my $meta = $self->meta;
906 my $meta_attr = $meta->find_attribute_by_name("immutable_trait");
910 if ( $meta_attr and $trait eq $meta_attr->default ) {
911 # if the trait is the same as the default we try and pick a
912 # predictable name for the immutable metaclass
913 $class_name = 'Class::MOP::Class::Immutable::' . ref($self);
916 $class_name = join '::', 'Class::MOP::Class::Immutable::CustomTrait',
917 $trait, 'ForMetaClass', ref($self);
921 if Class::MOP::is_class_loaded($class_name);
923 # If the metaclass is a subclass of CMOP::Class which has had
924 # metaclass roles applied (via Moose), then we want to make sure
925 # that we preserve that anonymous class (see Fey::ORM for an
926 # example of where this matters).
928 = $meta->is_immutable
929 ? $meta->_get_mutable_metaclass_name
932 my $immutable_meta = $meta_name->create(
934 superclasses => [ ref $self ],
937 Class::MOP::load_class($trait);
938 for my $meth ( Class::MOP::Class->initialize($trait)->get_all_methods ) {
939 my $meth_name = $meth->name;
941 if ( $immutable_meta->find_method_by_name( $meth_name ) ) {
942 $immutable_meta->add_around_method_modifier( $meth_name, $meth->body );
945 $immutable_meta->add_method( $meth_name, $meth->clone );
949 $immutable_meta->make_immutable(
950 inline_constructor => 0,
951 inline_accessors => 0,
957 sub _remove_inlined_code {
960 $self->remove_method( $_->name ) for $self->_inlined_methods;
962 delete $self->{__immutable}{inlined_methods};
965 sub _inlined_methods { @{ $_[0]{__immutable}{inlined_methods} || [] } }
967 sub _add_inlined_method {
968 my ( $self, $method ) = @_;
970 push @{ $self->{__immutable}{inlined_methods} ||= [] }, $method;
973 sub _initialize_immutable {
974 my ( $self, %args ) = @_;
976 $self->{__immutable}{options} = \%args;
977 $self->_install_inlined_code(%args);
980 sub _install_inlined_code {
981 my ( $self, %args ) = @_;
984 $self->_inline_accessors(%args) if $args{inline_accessors};
985 $self->_inline_constructor(%args) if $args{inline_constructor};
986 $self->_inline_destructor(%args) if $args{inline_destructor};
989 sub _rebless_as_mutable {
992 bless $self, $self->_get_mutable_metaclass_name;
997 sub _inline_accessors {
1000 foreach my $attr_name ( $self->get_attribute_list ) {
1001 $self->get_attribute($attr_name)->install_accessors(1);
1005 sub _inline_constructor {
1006 my ( $self, %args ) = @_;
1008 my $name = $args{constructor_name};
1009 # A class may not even have a constructor, and that's okay.
1010 return unless defined $name;
1012 if ( $self->has_method($name) && !$args{replace_constructor} ) {
1013 my $class = $self->name;
1014 warn "Not inlining a constructor for $class since it defines"
1015 . " its own constructor.\n"
1016 . "If you are certain you don't need to inline your"
1017 . " constructor, specify inline_constructor => 0 in your"
1018 . " call to $class->meta->make_immutable\n";
1022 my $constructor_class = $args{constructor_class};
1024 Class::MOP::load_class($constructor_class);
1026 my $constructor = $constructor_class->new(
1030 package_name => $self->name,
1034 if ( $args{replace_constructor} or $constructor->can_be_inlined ) {
1035 $self->add_method( $name => $constructor );
1036 $self->_add_inlined_method($constructor);
1040 sub _inline_destructor {
1041 my ( $self, %args ) = @_;
1043 ( exists $args{destructor_class} && defined $args{destructor_class} )
1044 || confess "The 'inline_destructor' option is present, but "
1045 . "no destructor class was specified";
1047 if ( $self->has_method('DESTROY') && ! $args{replace_destructor} ) {
1048 my $class = $self->name;
1049 warn "Not inlining a destructor for $class since it defines"
1050 . " its own destructor.\n";
1054 my $destructor_class = $args{destructor_class};
1056 Class::MOP::load_class($destructor_class);
1058 return unless $destructor_class->is_needed($self);
1060 my $destructor = $destructor_class->new(
1063 package_name => $self->name,
1067 if ( $args{replace_destructor} or $destructor->can_be_inlined ) {
1068 $self->add_method( 'DESTROY' => $destructor );
1069 $self->_add_inlined_method($destructor);
1081 Class::MOP::Class - Class Meta Object
1085 # assuming that class Foo
1086 # has been defined, you can
1088 # use this for introspection ...
1090 # add a method to Foo ...
1091 Foo->meta->add_method( 'bar' => sub {...} )
1093 # get a list of all the classes searched
1094 # the method dispatcher in the correct order
1095 Foo->meta->class_precedence_list()
1097 # remove a method from Foo
1098 Foo->meta->remove_method('bar');
1100 # or use this to actually create classes ...
1102 Class::MOP::Class->create(
1105 superclasses => ['Foo'],
1107 Class::MOP::Attribute->new('$bar'),
1108 Class::MOP::Attribute->new('$baz'),
1111 calculate_bar => sub {...},
1112 construct_baz => sub {...}
1119 The Class Protocol is the largest and most complex part of the
1120 Class::MOP meta-object protocol. It controls the introspection and
1121 manipulation of Perl 5 classes, and it can create them as well. The
1122 best way to understand what this module can do is to read the
1123 documentation for each of its methods.
1127 C<Class::MOP::Class> is a subclass of L<Class::MOP::Module>.
1131 =head2 Class construction
1133 These methods all create new C<Class::MOP::Class> objects. These
1134 objects can represent existing classes or they can be used to create
1135 new classes from scratch.
1137 The metaclass object for a given class is a singleton. If you attempt
1138 to create a metaclass for the same class twice, you will just get the
1143 =item B<< Class::MOP::Class->create($package_name, %options) >>
1145 This method creates a new C<Class::MOP::Class> object with the given
1146 package name. It accepts a number of options:
1152 An optional version number for the newly created package.
1156 An optional authority for the newly created package.
1158 =item * superclasses
1160 An optional array reference of superclass names.
1164 An optional hash reference of methods for the class. The keys of the
1165 hash reference are method names and values are subroutine references.
1169 An optional array reference of L<Class::MOP::Attribute> objects.
1173 =item B<< Class::MOP::Class->create_anon_class(%options) >>
1175 This method works just like C<< Class::MOP::Class->create >> but it
1176 creates an "anonymous" class. In fact, the class does have a name, but
1177 that name is a unique name generated internally by this module.
1179 It accepts the same C<superclasses>, C<methods>, and C<attributes>
1180 parameters that C<create> accepts.
1182 Anonymous classes are destroyed once the metaclass they are attached
1183 to goes out of scope, and will be removed from Perl's internal symbol
1186 All instances of an anonymous class keep a special reference to the
1187 metaclass object, which prevents the metaclass from going out of scope
1188 while any instances exist.
1190 This only works if the instance is based on a hash reference, however.
1192 =item B<< Class::MOP::Class->initialize($package_name, %options) >>
1194 This method will initialize a C<Class::MOP::Class> object for the
1195 named package. Unlike C<create>, this method I<will not> create a new
1198 The purpose of this method is to retrieve a C<Class::MOP::Class>
1199 object for introspecting an existing class.
1201 If an existing C<Class::MOP::Class> object exists for the named
1202 package, it will be returned, and any options provided will be
1205 If the object does not yet exist, it will be created.
1207 The valid options that can be passed to this method are
1208 C<attribute_metaclass>, C<method_metaclass>,
1209 C<wrapped_method_metaclass>, and C<instance_metaclass>. These are all
1210 optional, and default to the appropriate class in the C<Class::MOP>
1215 =head2 Object instance construction and cloning
1217 These methods are all related to creating and/or cloning object
1222 =item B<< $metaclass->clone_object($instance, %params) >>
1224 This method clones an existing object instance. Any parameters you
1225 provide are will override existing attribute values in the object.
1227 This is a convenience method for cloning an object instance, then
1228 blessing it into the appropriate package.
1230 You could implement a clone method in your class, using this method:
1233 my ($self, %params) = @_;
1234 $self->meta->clone_object($self, %params);
1237 =item B<< $metaclass->rebless_instance($instance, %params) >>
1239 This method changes the class of C<$instance> to the metaclass's class.
1241 You can only rebless an instance into a subclass of its current
1242 class. If you pass any additional parameters, these will be treated
1243 like constructor parameters and used to initialize the object's
1244 attributes. Any existing attributes that are already set will be
1247 Before reblessing the instance, this method will call
1248 C<rebless_instance_away> on the instance's current metaclass. This method
1249 will be passed the instance, the new metaclass, and any parameters
1250 specified to C<rebless_instance>. By default, C<rebless_instance_away>
1251 does nothing; it is merely a hook.
1253 =item B<< $metaclass->new_object(%params) >>
1255 This method is used to create a new object of the metaclass's
1256 class. Any parameters you provide are used to initialize the
1257 instance's attributes. A special C<__INSTANCE__> key can be passed to
1258 provide an already generated instance, rather than having Class::MOP
1259 generate it for you. This is mostly useful for using Class::MOP with
1260 foreign classes which generate instances using their own constructors.
1262 =item B<< $metaclass->instance_metaclass >>
1264 Returns the class name of the instance metaclass. See
1265 L<Class::MOP::Instance> for more information on the instance
1268 =item B<< $metaclass->get_meta_instance >>
1270 Returns an instance of the C<instance_metaclass> to be used in the
1271 construction of a new instance of the class.
1275 =head2 Informational predicates
1277 These are a few predicate methods for asking information about the
1282 =item B<< $metaclass->is_anon_class >>
1284 This returns true if the class was created by calling C<<
1285 Class::MOP::Class->create_anon_class >>.
1287 =item B<< $metaclass->is_mutable >>
1289 This returns true if the class is still mutable.
1291 =item B<< $metaclass->is_immutable >>
1293 This returns true if the class has been made immutable.
1295 =item B<< $metaclass->is_pristine >>
1297 A class is I<not> pristine if it has non-inherited attributes or if it
1298 has any generated methods.
1302 =head2 Inheritance Relationships
1306 =item B<< $metaclass->superclasses(@superclasses) >>
1308 This is a read-write accessor which represents the superclass
1309 relationships of the metaclass's class.
1311 This is basically sugar around getting and setting C<@ISA>.
1313 =item B<< $metaclass->class_precedence_list >>
1315 This returns a list of all of the class's ancestor classes. The
1316 classes are returned in method dispatch order.
1318 =item B<< $metaclass->linearized_isa >>
1320 This returns a list based on C<class_precedence_list> but with all
1323 =item B<< $metaclass->subclasses >>
1325 This returns a list of all subclasses for this class, even indirect
1328 =item B<< $metaclass->direct_subclasses >>
1330 This returns a list of immediate subclasses for this class, which does not
1331 include indirect subclasses.
1335 =head2 Method introspection
1337 See L<Class::MOP::Package/Method introspection and creation> for
1338 methods that operate only on the current class. Class::MOP::Class adds
1339 introspection capabilities that take inheritance into account.
1343 =item B<< $metaclass->get_all_methods >>
1345 This will traverse the inheritance hierarchy and return a list of all
1346 the L<Class::MOP::Method> objects for this class and its parents.
1348 =item B<< $metaclass->find_method_by_name($method_name) >>
1350 This will return a L<Class::MOP::Method> for the specified
1351 C<$method_name>. If the class does not have the specified method, it
1354 Unlike C<get_method>, this method I<will> look for the named method in
1357 =item B<< $metaclass->get_all_method_names >>
1359 This will return a list of method I<names> for all of this class's
1360 methods, including inherited methods.
1362 =item B<< $metaclass->find_all_methods_by_name($method_name) >>
1364 This method looks for the named method in the class and all of its
1365 parents. It returns every matching method it finds in the inheritance
1366 tree, so it returns a list of methods.
1368 Each method is returned as a hash reference with three keys. The keys
1369 are C<name>, C<class>, and C<code>. The C<code> key has a
1370 L<Class::MOP::Method> object as its value.
1372 The list of methods is distinct.
1374 =item B<< $metaclass->find_next_method_by_name($method_name) >>
1376 This method returns the first method in any superclass matching the
1377 given name. It is effectively the method that C<SUPER::$method_name>
1382 =head2 Attribute introspection and creation
1384 Because Perl 5 does not have a core concept of attributes in classes,
1385 we can only return information about attributes which have been added
1386 via this class's methods. We cannot discover information about
1387 attributes which are defined in terms of "regular" Perl 5 methods.
1391 =item B<< $metaclass->get_attribute($attribute_name) >>
1393 This will return a L<Class::MOP::Attribute> for the specified
1394 C<$attribute_name>. If the class does not have the specified
1395 attribute, it returns C<undef>.
1397 NOTE that get_attribute does not search superclasses, for that you
1398 need to use C<find_attribute_by_name>.
1400 =item B<< $metaclass->has_attribute($attribute_name) >>
1402 Returns a boolean indicating whether or not the class defines the
1403 named attribute. It does not include attributes inherited from parent
1406 =item B<< $metaclass->get_attribute_list >>
1408 This will return a list of attributes I<names> for all attributes
1409 defined in this class.
1411 =item B<< $metaclass->get_all_attributes >>
1413 This will traverse the inheritance hierarchy and return a list of all
1414 the L<Class::MOP::Attribute> objects for this class and its parents.
1416 =item B<< $metaclass->find_attribute_by_name($attribute_name) >>
1418 This will return a L<Class::MOP::Attribute> for the specified
1419 C<$attribute_name>. If the class does not have the specified
1420 attribute, it returns C<undef>.
1422 Unlike C<get_attribute>, this attribute I<will> look for the named
1423 attribute in superclasses.
1425 =item B<< $metaclass->add_attribute(...) >>
1427 This method accepts either an existing L<Class::MOP::Attribute>
1428 object or parameters suitable for passing to that class's C<new>
1431 The attribute provided will be added to the class.
1433 Any accessor methods defined by the attribute will be added to the
1434 class when the attribute is added.
1436 If an attribute of the same name already exists, the old attribute
1437 will be removed first.
1439 =item B<< $metaclass->remove_attribute($attribute_name) >>
1441 This will remove the named attribute from the class, and
1442 L<Class::MOP::Attribute> object.
1444 Removing an attribute also removes any accessor methods defined by the
1447 However, note that removing an attribute will only affect I<future>
1448 object instances created for this class, not existing instances.
1450 =item B<< $metaclass->attribute_metaclass >>
1452 Returns the class name of the attribute metaclass for this class. By
1453 default, this is L<Class::MOP::Attribute>.
1457 =head2 Class Immutability
1459 Making a class immutable "freezes" the class definition. You can no
1460 longer call methods which alter the class, such as adding or removing
1461 methods or attributes.
1463 Making a class immutable lets us optimize the class by inlining some
1464 methods, and also allows us to optimize some methods on the metaclass
1467 After immutabilization, the metaclass object will cache most informational
1468 methods that returns information about methods or attributes. Methods which
1469 would alter the class, such as C<add_attribute> and C<add_method>, will
1470 throw an error on an immutable metaclass object.
1472 The immutabilization system in L<Moose> takes much greater advantage
1473 of the inlining features than Class::MOP itself does.
1477 =item B<< $metaclass->make_immutable(%options) >>
1479 This method will create an immutable transformer and use it to make
1480 the class and its metaclass object immutable.
1482 This method accepts the following options:
1486 =item * inline_accessors
1488 =item * inline_constructor
1490 =item * inline_destructor
1492 These are all booleans indicating whether the specified method(s)
1495 By default, accessors and the constructor are inlined, but not the
1498 =item * immutable_trait
1500 The name of a class which will be used as a parent class for the
1501 metaclass object being made immutable. This "trait" implements the
1502 post-immutability functionality of the metaclass (but not the
1503 transformation itself).
1505 This defaults to L<Class::MOP::Class::Immutable::Trait>.
1507 =item * constructor_name
1509 This is the constructor method name. This defaults to "new".
1511 =item * constructor_class
1513 The name of the method metaclass for constructors. It will be used to
1514 generate the inlined constructor. This defaults to
1515 "Class::MOP::Method::Constructor".
1517 =item * replace_constructor
1519 This is a boolean indicating whether an existing constructor should be
1520 replaced when inlining a constructor. This defaults to false.
1522 =item * destructor_class
1524 The name of the method metaclass for destructors. It will be used to
1525 generate the inlined destructor. This defaults to
1526 "Class::MOP::Method::Denstructor".
1528 =item * replace_destructor
1530 This is a boolean indicating whether an existing destructor should be
1531 replaced when inlining a destructor. This defaults to false.
1535 =item B<< $metaclass->immutable_options >>
1537 Returns a hash of the options used when making the class immutable, including
1538 both defaults and anything supplied by the user in the call to C<<
1539 $metaclass->make_immutable >>. This is useful if you need to temporarily make
1540 a class mutable and then restore immutability as it was before.
1542 =item B<< $metaclass->make_mutable >>
1544 Calling this method reverse the immutabilization transformation.
1548 =head2 Method Modifiers
1550 Method modifiers are hooks which allow a method to be wrapped with
1551 I<before>, I<after> and I<around> method modifiers. Every time a
1552 method is called, its modifiers are also called.
1554 A class can modify its own methods, as well as methods defined in
1557 =head3 How method modifiers work?
1559 Method modifiers work by wrapping the original method and then
1560 replacing it in the class's symbol table. The wrappers will handle
1561 calling all the modifiers in the appropriate order and preserving the
1562 calling context for the original method.
1564 The return values of C<before> and C<after> modifiers are
1565 ignored. This is because their purpose is B<not> to filter the input
1566 and output of the primary method (this is done with an I<around>
1569 This may seem like an odd restriction to some, but doing this allows
1570 for simple code to be added at the beginning or end of a method call
1571 without altering the function of the wrapped method or placing any
1572 extra responsibility on the code of the modifier.
1574 Of course if you have more complex needs, you can use the C<around>
1575 modifier which allows you to change both the parameters passed to the
1576 wrapped method, as well as its return value.
1578 Before and around modifiers are called in last-defined-first-called
1579 order, while after modifiers are called in first-defined-first-called
1580 order. So the call tree might looks something like this:
1592 =head3 What is the performance impact?
1594 Of course there is a performance cost associated with method
1595 modifiers, but we have made every effort to make that cost directly
1596 proportional to the number of modifier features you use.
1598 The wrapping method does its best to B<only> do as much work as it
1599 absolutely needs to. In order to do this we have moved some of the
1600 performance costs to set-up time, where they are easier to amortize.
1602 All this said, our benchmarks have indicated the following:
1604 simple wrapper with no modifiers 100% slower
1605 simple wrapper with simple before modifier 400% slower
1606 simple wrapper with simple after modifier 450% slower
1607 simple wrapper with simple around modifier 500-550% slower
1608 simple wrapper with all 3 modifiers 1100% slower
1610 These numbers may seem daunting, but you must remember, every feature
1611 comes with some cost. To put things in perspective, just doing a
1612 simple C<AUTOLOAD> which does nothing but extract the name of the
1613 method called and return it costs about 400% over a normal method
1618 =item B<< $metaclass->add_before_method_modifier($method_name, $code) >>
1620 This wraps the specified method with the supplied subroutine
1621 reference. The modifier will be called as a method itself, and will
1622 receive the same arguments as are passed to the method.
1624 When the modifier exits, the wrapped method will be called.
1626 The return value of the modifier will be ignored.
1628 =item B<< $metaclass->add_after_method_modifier($method_name, $code) >>
1630 This wraps the specified method with the supplied subroutine
1631 reference. The modifier will be called as a method itself, and will
1632 receive the same arguments as are passed to the method.
1634 When the wrapped methods exits, the modifier will be called.
1636 The return value of the modifier will be ignored.
1638 =item B<< $metaclass->add_around_method_modifier($method_name, $code) >>
1640 This wraps the specified method with the supplied subroutine
1643 The first argument passed to the modifier will be a subroutine
1644 reference to the wrapped method. The second argument is the object,
1645 and after that come any arguments passed when the method is called.
1647 The around modifier can choose to call the original method, as well as
1648 what arguments to pass if it does so.
1650 The return value of the modifier is what will be seen by the caller.
1654 =head2 Introspection
1658 =item B<< Class::MOP::Class->meta >>
1660 This will return a L<Class::MOP::Class> instance for this class.
1662 It should also be noted that L<Class::MOP> will actually bootstrap
1663 this module by installing a number of attribute meta-objects into its
1670 Stevan Little E<lt>stevan@iinteractive.comE<gt>
1672 =head1 COPYRIGHT AND LICENSE
1674 Copyright 2006-2009 by Infinity Interactive, Inc.
1676 L<http://www.iinteractive.com>
1678 This library is free software; you can redistribute it and/or modify
1679 it under the same terms as Perl itself.