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 = '0.92_01';
18 $VERSION = eval $VERSION;
19 our $AUTHORITY = 'cpan:STEVAN';
21 use base 'Class::MOP::Module';
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,
124 # inherited from Class::MOP::Module
126 'authority' => \undef,
128 # defined in Class::MOP::Class
129 '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;
246 # Moose does a weird thing where it replaces the metaclass for
247 # class when fixing metaclass incompatibility. In that case,
248 # we don't want to clean out the namespace now. We can detect
249 # that because Moose will explicitly update the singleton
250 # cache in Class::MOP.
251 my $current_meta = Class::MOP::get_metaclass_by_name($name);
252 return if $current_meta ne $self;
254 my ($serial_id) = ($name =~ /^$ANON_CLASS_PREFIX(\d+)/o);
256 @{$name . '::ISA'} = ();
257 %{$name . '::'} = ();
258 delete ${$ANON_CLASS_PREFIX}{$serial_id . '::'};
260 Class::MOP::remove_metaclass_by_name($name);
265 # creating classes with MOP ...
268 my ( $class, @args ) = @_;
270 unshift @args, 'package' if @args % 2 == 1;
272 my (%options) = @args;
273 my $package_name = $options{package};
275 (ref $options{superclasses} eq 'ARRAY')
276 || confess "You must pass an ARRAY ref of superclasses"
277 if exists $options{superclasses};
279 (ref $options{attributes} eq 'ARRAY')
280 || confess "You must pass an ARRAY ref of attributes"
281 if exists $options{attributes};
283 (ref $options{methods} eq 'HASH')
284 || confess "You must pass a HASH ref of methods"
285 if exists $options{methods};
287 my (%initialize_options) = @args;
288 delete @initialize_options{qw(
296 my $meta = $class->initialize( $package_name => %initialize_options );
298 $meta->_instantiate_module( $options{version}, $options{authority} );
301 $meta->add_method('meta' => sub {
302 $class->initialize(ref($_[0]) || $_[0]);
305 $meta->superclasses(@{$options{superclasses}})
306 if exists $options{superclasses};
308 # process attributes first, so that they can
309 # install accessors, but locally defined methods
310 # can then overwrite them. It is maybe a little odd, but
311 # I think this should be the order of things.
312 if (exists $options{attributes}) {
313 foreach my $attr (@{$options{attributes}}) {
314 $meta->add_attribute($attr);
317 if (exists $options{methods}) {
318 foreach my $method_name (keys %{$options{methods}}) {
319 $meta->add_method($method_name, $options{methods}->{$method_name});
328 # all these attribute readers will be bootstrapped
329 # away in the Class::MOP bootstrap section
331 sub get_attribute_map { $_[0]->{'attributes'} }
332 sub attribute_metaclass { $_[0]->{'attribute_metaclass'} }
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
476 my $var_spec = { sigil => '@', type => 'ARRAY', name => 'ISA' };
479 @{$self->get_package_symbol($var_spec)} = @supers;
482 # on 5.8 and below, we need to call
483 # a method to get Perl to detect
484 # a cycle in the class hierarchy
485 my $class = $self->name;
489 # we need to check the metaclass
490 # compatibility here so that we can
491 # be sure that the superclass is
492 # not potentially creating an issues
493 # we don't know about
495 $self->_check_metaclass_compatibility();
496 $self->_superclasses_updated();
498 @{$self->get_package_symbol($var_spec)};
501 sub _superclasses_updated {
503 $self->update_meta_instance_dependencies();
508 my $super_class = $self->name;
510 return @{ $super_class->mro::get_isarev() };
513 sub direct_subclasses {
515 my $super_class = $self->name;
520 } Class::MOP::Class->initialize($_)->superclasses
525 return @{ mro::get_linear_isa( (shift)->name ) };
528 sub class_precedence_list {
530 my $name = $self->name;
532 unless (Class::MOP::IS_RUNNING_ON_5_10()) {
534 # We need to check for circular inheritance here
535 # if we are are not on 5.10, cause 5.8 detects it
536 # late. This will do nothing if all is well, and
537 # blow up otherwise. Yes, it's an ugly hack, better
538 # suggestions are welcome.
540 ($name || return)->isa('This is a test for circular inheritance')
543 # if our mro is c3, we can
544 # just grab the linear_isa
545 if (mro::get_mro($name) eq 'c3') {
546 return @{ mro::get_linear_isa($name) }
550 # we can't grab the linear_isa for dfs
551 # since it has all the duplicates
556 $self->initialize($_)->class_precedence_list()
557 } $self->superclasses()
565 my $fetch_and_prepare_method = sub {
566 my ($self, $method_name) = @_;
567 my $wrapped_metaclass = $self->wrapped_method_metaclass;
569 my $method = $self->get_method($method_name);
570 # if we dont have local ...
572 # try to find the next method
573 $method = $self->find_next_method_by_name($method_name);
574 # die if it does not exist
576 || confess "The method '$method_name' was not found in the inheritance hierarchy for " . $self->name;
577 # and now make sure to wrap it
578 # even if it is already wrapped
579 # because we need a new sub ref
580 $method = $wrapped_metaclass->wrap($method,
581 package_name => $self->name,
582 name => $method_name,
586 # now make sure we wrap it properly
587 $method = $wrapped_metaclass->wrap($method,
588 package_name => $self->name,
589 name => $method_name,
590 ) unless $method->isa($wrapped_metaclass);
592 $self->add_method($method_name => $method);
596 sub add_before_method_modifier {
597 my ($self, $method_name, $method_modifier) = @_;
598 (defined $method_name && $method_name)
599 || confess "You must pass in a method name";
600 my $method = $fetch_and_prepare_method->($self, $method_name);
601 $method->add_before_modifier(
602 subname(':before' => $method_modifier)
606 sub add_after_method_modifier {
607 my ($self, $method_name, $method_modifier) = @_;
608 (defined $method_name && $method_name)
609 || confess "You must pass in a method name";
610 my $method = $fetch_and_prepare_method->($self, $method_name);
611 $method->add_after_modifier(
612 subname(':after' => $method_modifier)
616 sub add_around_method_modifier {
617 my ($self, $method_name, $method_modifier) = @_;
618 (defined $method_name && $method_name)
619 || confess "You must pass in a method name";
620 my $method = $fetch_and_prepare_method->($self, $method_name);
621 $method->add_around_modifier(
622 subname(':around' => $method_modifier)
627 # the methods above used to be named like this:
628 # ${pkg}::${method}:(before|after|around)
629 # but this proved problematic when using one modifier
630 # to wrap multiple methods (something which is likely
631 # to happen pretty regularly IMO). So instead of naming
632 # it like this, I have chosen to just name them purely
633 # with their modifier names, like so:
634 # :(before|after|around)
635 # The fact is that in a stack trace, it will be fairly
636 # evident from the context what method they are attached
637 # to, and so don't need the fully qualified name.
640 sub find_method_by_name {
641 my ($self, $method_name) = @_;
642 (defined $method_name && $method_name)
643 || confess "You must define a method name to find";
644 foreach my $class ($self->linearized_isa) {
645 my $method = $self->initialize($class)->get_method($method_name);
646 return $method if defined $method;
651 sub get_all_methods {
653 my %methods = map { %{ $self->initialize($_)->get_method_map } } reverse $self->linearized_isa;
654 return values %methods;
657 sub get_all_method_names {
660 return grep { !$uniq{$_}++ } map { $self->initialize($_)->get_method_list } $self->linearized_isa;
663 sub find_all_methods_by_name {
664 my ($self, $method_name) = @_;
665 (defined $method_name && $method_name)
666 || confess "You must define a method name to find";
668 foreach my $class ($self->linearized_isa) {
669 # fetch the meta-class ...
670 my $meta = $self->initialize($class);
672 name => $method_name,
674 code => $meta->get_method($method_name)
675 } if $meta->has_method($method_name);
680 sub find_next_method_by_name {
681 my ($self, $method_name) = @_;
682 (defined $method_name && $method_name)
683 || confess "You must define a method name to find";
684 my @cpl = $self->linearized_isa;
685 shift @cpl; # discard ourselves
686 foreach my $class (@cpl) {
687 my $method = $self->initialize($class)->get_method($method_name);
688 return $method if defined $method;
697 # either we have an attribute object already
698 # or we need to create one from the args provided
699 my $attribute = blessed($_[0]) ? $_[0] : $self->attribute_metaclass->new(@_);
700 # make sure it is derived from the correct type though
701 ($attribute->isa('Class::MOP::Attribute'))
702 || confess "Your attribute must be an instance of Class::MOP::Attribute (or a subclass)";
704 # first we attach our new attribute
705 # because it might need certain information
706 # about the class which it is attached to
707 $attribute->attach_to_class($self);
709 my $attr_name = $attribute->name;
711 # then we remove attributes of a conflicting
712 # name here so that we can properly detach
713 # the old attr object, and remove any
714 # accessors it would have generated
715 if ( $self->has_attribute($attr_name) ) {
716 $self->remove_attribute($attr_name);
718 $self->invalidate_meta_instances();
721 # get our count of previously inserted attributes and
722 # increment by one so this attribute knows its order
723 my $order = (scalar keys %{$self->get_attribute_map});
724 $attribute->_set_insertion_order($order);
726 # then onto installing the new accessors
727 $self->get_attribute_map->{$attr_name} = $attribute;
729 # invalidate package flag here
733 eval { $attribute->install_accessors() };
737 $self->remove_attribute($attr_name);
744 sub update_meta_instance_dependencies {
747 if ( $self->{meta_instance_dependencies} ) {
748 return $self->add_meta_instance_dependencies;
752 sub add_meta_instance_dependencies {
755 $self->remove_meta_instance_dependencies;
757 my @attrs = $self->get_all_attributes();
760 my @classes = grep { not $seen{$_->name}++ } map { $_->associated_class } @attrs;
762 foreach my $class ( @classes ) {
763 $class->add_dependent_meta_instance($self);
766 $self->{meta_instance_dependencies} = \@classes;
769 sub remove_meta_instance_dependencies {
772 if ( my $classes = delete $self->{meta_instance_dependencies} ) {
773 foreach my $class ( @$classes ) {
774 $class->remove_dependent_meta_instance($self);
784 sub add_dependent_meta_instance {
785 my ( $self, $metaclass ) = @_;
786 push @{ $self->{dependent_meta_instances} }, $metaclass;
789 sub remove_dependent_meta_instance {
790 my ( $self, $metaclass ) = @_;
791 my $name = $metaclass->name;
792 @$_ = grep { $_->name ne $name } @$_ for $self->{dependent_meta_instances};
795 sub invalidate_meta_instances {
797 $_->invalidate_meta_instance() for $self, @{ $self->{dependent_meta_instances} };
800 sub invalidate_meta_instance {
802 undef $self->{_meta_instance};
806 my ($self, $attribute_name) = @_;
807 (defined $attribute_name)
808 || confess "You must define an attribute name";
809 exists $self->get_attribute_map->{$attribute_name};
813 my ($self, $attribute_name) = @_;
814 (defined $attribute_name)
815 || confess "You must define an attribute name";
816 return $self->get_attribute_map->{$attribute_name}
818 # this will return undef anyway, so no need ...
819 # if $self->has_attribute($attribute_name);
823 sub remove_attribute {
824 my ($self, $attribute_name) = @_;
825 (defined $attribute_name)
826 || confess "You must define an attribute name";
827 my $removed_attribute = $self->get_attribute_map->{$attribute_name};
828 return unless defined $removed_attribute;
829 delete $self->get_attribute_map->{$attribute_name};
830 $self->invalidate_meta_instances();
831 $removed_attribute->remove_accessors();
832 $removed_attribute->detach_from_class();
833 return $removed_attribute;
836 sub get_attribute_list {
838 keys %{$self->get_attribute_map};
841 sub get_all_attributes {
843 my %attrs = map { %{ $self->initialize($_)->get_attribute_map } } reverse $self->linearized_isa;
844 return values %attrs;
847 sub find_attribute_by_name {
848 my ($self, $attr_name) = @_;
849 foreach my $class ($self->linearized_isa) {
850 # fetch the meta-class ...
851 my $meta = $self->initialize($class);
852 return $meta->get_attribute($attr_name)
853 if $meta->has_attribute($attr_name);
858 # check if we can reinitialize
862 # if any local attr is defined
863 return if $self->get_attribute_list;
865 # or any non-declared methods
866 if ( my @methods = values %{ $self->get_method_map } ) {
867 my $metaclass = $self->method_metaclass;
868 foreach my $method ( @methods ) {
869 return if $method->isa("Class::MOP::Method::Generated");
870 # FIXME do we need to enforce this too? return unless $method->isa($metaclass);
880 sub is_immutable { 0 }
882 sub immutable_options { %{ $_[0]{__immutable}{options} || {} } }
884 sub _immutable_options {
885 my ( $self, @args ) = @_;
888 inline_accessors => 1,
889 inline_constructor => 1,
890 inline_destructor => 0,
892 immutable_trait => $self->immutable_trait,
893 constructor_name => $self->constructor_name,
894 constructor_class => $self->constructor_class,
895 destructor_class => $self->destructor_class,
901 my ( $self, @args ) = @_;
903 if ( $self->is_mutable ) {
904 $self->_initialize_immutable( $self->_immutable_options(@args) );
905 $self->_rebless_as_immutable(@args);
916 if ( $self->is_immutable ) {
917 my @args = $self->immutable_options;
918 $self->_rebless_as_mutable();
919 $self->_remove_inlined_code(@args);
920 delete $self->{__immutable};
928 sub _rebless_as_immutable {
929 my ( $self, @args ) = @_;
931 $self->{__immutable}{original_class} = ref $self;
933 bless $self => $self->_immutable_metaclass(@args);
936 sub _immutable_metaclass {
937 my ( $self, %args ) = @_;
939 if ( my $class = $args{immutable_metaclass} ) {
943 my $trait = $args{immutable_trait} = $self->immutable_trait
944 || confess "no immutable trait specified for $self";
946 my $meta = $self->meta;
947 my $meta_attr = $meta->find_attribute_by_name("immutable_trait");
951 if ( $meta_attr and $trait eq $meta_attr->default ) {
952 # if the trait is the same as the default we try and pick a
953 # predictable name for the immutable metaclass
954 $class_name = 'Class::MOP::Class::Immutable::' . ref($self);
957 $class_name = join '::', 'Class::MOP::Class::Immutable::CustomTrait',
958 $trait, 'ForMetaClass', ref($self);
962 if Class::MOP::is_class_loaded($class_name);
964 # If the metaclass is a subclass of CMOP::Class which has had
965 # metaclass roles applied (via Moose), then we want to make sure
966 # that we preserve that anonymous class (see Fey::ORM for an
967 # example of where this matters).
969 = $meta->is_immutable
970 ? $meta->_get_mutable_metaclass_name
973 my $immutable_meta = $meta_name->create(
975 superclasses => [ ref $self ],
978 Class::MOP::load_class($trait);
979 for my $meth ( Class::MOP::Class->initialize($trait)->get_all_methods ) {
980 my $meth_name = $meth->name;
982 if ( $immutable_meta->find_method_by_name( $meth_name ) ) {
983 $immutable_meta->add_around_method_modifier( $meth_name, $meth->body );
986 $immutable_meta->add_method( $meth_name, $meth->clone );
990 $immutable_meta->make_immutable(
991 inline_constructor => 0,
992 inline_accessors => 0,
998 sub _remove_inlined_code {
1001 $self->remove_method( $_->name ) for $self->_inlined_methods;
1003 delete $self->{__immutable}{inlined_methods};
1006 sub _inlined_methods { @{ $_[0]{__immutable}{inlined_methods} || [] } }
1008 sub _add_inlined_method {
1009 my ( $self, $method ) = @_;
1011 push @{ $self->{__immutable}{inlined_methods} ||= [] }, $method;
1014 sub _initialize_immutable {
1015 my ( $self, %args ) = @_;
1017 $self->{__immutable}{options} = \%args;
1018 $self->_install_inlined_code(%args);
1021 sub _install_inlined_code {
1022 my ( $self, %args ) = @_;
1025 $self->_inline_accessors(%args) if $args{inline_accessors};
1026 $self->_inline_constructor(%args) if $args{inline_constructor};
1027 $self->_inline_destructor(%args) if $args{inline_destructor};
1030 sub _rebless_as_mutable {
1033 bless $self, $self->_get_mutable_metaclass_name;
1038 sub _inline_accessors {
1041 foreach my $attr_name ( $self->get_attribute_list ) {
1042 $self->get_attribute($attr_name)->install_accessors(1);
1046 sub _inline_constructor {
1047 my ( $self, %args ) = @_;
1049 my $name = $args{constructor_name};
1051 if ( $self->has_method($name) && !$args{replace_constructor} ) {
1052 my $class = $self->name;
1053 warn "Not inlining a constructor for $class since it defines"
1054 . " its own constructor.\n"
1055 . "If you are certain you don't need to inline your"
1056 . " constructor, specify inline_constructor => 0 in your"
1057 . " call to $class->meta->make_immutable\n";
1061 my $constructor_class = $args{constructor_class};
1063 Class::MOP::load_class($constructor_class);
1065 my $constructor = $constructor_class->new(
1069 package_name => $self->name,
1073 if ( $args{replace_constructor} or $constructor->can_be_inlined ) {
1074 $self->add_method( $name => $constructor );
1075 $self->_add_inlined_method($constructor);
1079 sub _inline_destructor {
1080 my ( $self, %args ) = @_;
1082 ( exists $args{destructor_class} && defined $args{destructor_class} )
1083 || confess "The 'inline_destructor' option is present, but "
1084 . "no destructor class was specified";
1086 if ( $self->has_method('DESTROY') && ! $args{replace_destructor} ) {
1087 my $class = $self->name;
1088 warn "Not inlining a destructor for $class since it defines"
1089 . " its own destructor.\n";
1093 my $destructor_class = $args{destructor_class};
1095 Class::MOP::load_class($destructor_class);
1097 return unless $destructor_class->is_needed($self);
1099 my $destructor = $destructor_class->new(
1102 package_name => $self->name,
1106 if ( $args{replace_destructor} or $destructor->can_be_inlined ) {
1107 $self->add_method( 'DESTROY' => $destructor );
1108 $self->_add_inlined_method($destructor);
1120 Class::MOP::Class - Class Meta Object
1124 # assuming that class Foo
1125 # has been defined, you can
1127 # use this for introspection ...
1129 # add a method to Foo ...
1130 Foo->meta->add_method( 'bar' => sub {...} )
1132 # get a list of all the classes searched
1133 # the method dispatcher in the correct order
1134 Foo->meta->class_precedence_list()
1136 # remove a method from Foo
1137 Foo->meta->remove_method('bar');
1139 # or use this to actually create classes ...
1141 Class::MOP::Class->create(
1144 superclasses => ['Foo'],
1146 Class::MOP::Attribute->new('$bar'),
1147 Class::MOP::Attribute->new('$baz'),
1150 calculate_bar => sub {...},
1151 construct_baz => sub {...}
1158 The Class Protocol is the largest and most complex part of the
1159 Class::MOP meta-object protocol. It controls the introspection and
1160 manipulation of Perl 5 classes, and it can create them as well. The
1161 best way to understand what this module can do, is to read the
1162 documentation for each of its methods.
1166 C<Class::MOP::Class> is a subclass of L<Class::MOP::Module>.
1170 =head2 Class construction
1172 These methods all create new C<Class::MOP::Class> objects. These
1173 objects can represent existing classes, or they can be used to create
1174 new classes from scratch.
1176 The metaclass object for a given class is a singleton. If you attempt
1177 to create a metaclass for the same class twice, you will just get the
1182 =item B<< Class::MOP::Class->create($package_name, %options) >>
1184 This method creates a new C<Class::MOP::Class> object with the given
1185 package name. It accepts a number of options.
1191 An optional version number for the newly created package.
1195 An optional authority for the newly created package.
1197 =item * superclasses
1199 An optional array reference of superclass names.
1203 An optional hash reference of methods for the class. The keys of the
1204 hash reference are method names, and values are subroutine references.
1208 An optional array reference of L<Class::MOP::Attribute> objects.
1212 =item B<< Class::MOP::Class->create_anon_class(%options) >>
1214 This method works just like C<< Class::MOP::Class->create >> but it
1215 creates an "anonymous" class. In fact, the class does have a name, but
1216 that name is a unique name generated internally by this module.
1218 It accepts the same C<superclasses>, C<methods>, and C<attributes>
1219 parameters that C<create> accepts.
1221 Anonymous classes are destroyed once the metaclass they are attached
1222 to goes out of scope, and will be removed from Perl's internal symbol
1225 All instances of an anonymous class keep a special reference to the
1226 metaclass object, which prevents the metaclass from going out of scope
1227 while any instances exist.
1229 This only works if the instance if based on a hash reference, however.
1231 =item B<< Class::MOP::Class->initialize($package_name, %options) >>
1233 This method will initialize a C<Class::MOP::Class> object for the
1234 named package. Unlike C<create>, this method I<will not> create a new
1237 The purpose of this method is to retrieve a C<Class::MOP::Class>
1238 object for introspecting an existing class.
1240 If an existing C<Class::MOP::Class> object exists for the named
1241 package, it will be returned, and any options provided will be
1244 If the object does not yet exist, it will be created.
1246 The valid options that can be passed to this method are
1247 C<attribute_metaclass>, C<method_metaclass>,
1248 C<wrapped_method_metaclass>, and C<instance_metaclass>. These are all
1249 optional, and default to the appropriate class in the C<Class::MOP>
1254 =head2 Object instance construction and cloning
1256 These methods are all related to creating and/or cloning object
1261 =item B<< $metaclass->clone_object($instance, %params) >>
1263 This method clones an existing object instance. Any parameters you
1264 provide are will override existing attribute values in the object.
1266 This is a convenience method for cloning an object instance, then
1267 blessing it into the appropriate package.
1269 You could implement a clone method in your class, using this method:
1272 my ($self, %params) = @_;
1273 $self->meta->clone_object($self, %params);
1276 =item B<< $metaclass->rebless_instance($instance, %params) >>
1278 This method changes the class of C<$instance> to the metaclass's class.
1280 You can only rebless an instance into a subclass of its current
1281 class. If you pass any additional parameters, these will be treated
1282 like constructor parameters and used to initialize the object's
1283 attributes. Any existing attributes that are already set will be
1286 Before reblessing the instance, this method will call
1287 C<rebless_instance_away> on the instance's current metaclass. This method
1288 will be passed the instance, the new metaclass, and any parameters
1289 specified to C<rebless_instance>. By default, C<rebless_instance_away>
1290 does nothing; it is merely a hook.
1292 =item B<< $metaclass->new_object(%params) >>
1294 This method is used to create a new object of the metaclass's
1295 class. Any parameters you provide are used to initialize the
1296 instance's attributes. A special C<__INSTANCE__> key can be passed to
1297 provide an already generated instance, rather than having Class::MOP
1298 generate it for you. This is mostly useful for using Class::MOP with
1299 foreign classes, which generally generate instances using their own
1302 =item B<< $metaclass->instance_metaclass >>
1304 Returns the class name of the instance metaclass, see
1305 L<Class::MOP::Instance> for more information on the instance
1308 =item B<< $metaclass->get_meta_instance >>
1310 Returns an instance of the C<instance_metaclass> to be used in the
1311 construction of a new instance of the class.
1315 =head2 Informational predicates
1317 These are a few predicate methods for asking information about the
1322 =item B<< $metaclass->is_anon_class >>
1324 This returns true if the class was created by calling C<<
1325 Class::MOP::Class->create_anon_class >>.
1327 =item B<< $metaclass->is_mutable >>
1329 This returns true if the class is still mutable.
1331 =item B<< $metaclass->is_immutable >>
1333 This returns true if the class has been made immutable.
1335 =item B<< $metaclass->is_pristine >>
1337 A class is I<not> pristine if it has non-inherited attributes or if it
1338 has any generated methods.
1342 =head2 Inheritance Relationships
1346 =item B<< $metaclass->superclasses(@superclasses) >>
1348 This is a read-write accessor which represents the superclass
1349 relationships of the metaclass's class.
1351 This is basically sugar around getting and setting C<@ISA>.
1353 =item B<< $metaclass->class_precedence_list >>
1355 This returns a list of all of the class's ancestor classes. The
1356 classes are returned in method dispatch order.
1358 =item B<< $metaclass->linearized_isa >>
1360 This returns a list based on C<class_precedence_list> but with all
1363 =item B<< $metaclass->subclasses >>
1365 This returns a list of all subclasses for this class, even indirect
1368 =item B<< $metaclass->direct_subclasses >>
1370 This returns a list of immediate subclasses for this class, which does not
1371 include indirect subclasses.
1375 =head2 Method introspection
1377 See L<Class::MOP::Package/Method introspection and creation> for
1378 methods that operate only on the current class. Class::MOP::Class adds
1379 introspection capabilities that take inheritance into account.
1383 =item B<< $metaclass->get_all_methods >>
1385 This will traverse the inheritance hierarchy and return a list of all
1386 the L<Class::MOP::Method> objects for this class and its parents.
1388 =item B<< $metaclass->find_method_by_name($method_name) >>
1390 This will return a L<Class::MOP::Method> for the specified
1391 C<$method_name>. If the class does not have the specified method, it
1394 Unlike C<get_method>, this method I<will> look for the named method in
1397 =item B<< $metaclass->get_all_method_names >>
1399 This will return a list of method I<names> for all of this class's
1400 methods, including inherited methods.
1402 =item B<< $metaclass->find_all_methods_by_name($method_name) >>
1404 This method looks for the named method in the class and all of its
1405 parents. It returns every matching method it finds in the inheritance
1406 tree, so it returns a list of methods.
1408 Each method is returned as a hash reference with three keys. The keys
1409 are C<name>, C<class>, and C<code>. The C<code> key has a
1410 L<Class::MOP::Method> object as its value.
1412 The list of methods is distinct.
1414 =item B<< $metaclass->find_next_method_by_name($method_name) >>
1416 This method returns the first method in any superclass matching the
1417 given name. It is effectively the method that C<SUPER::$method_name>
1422 =head2 Attribute introspection and creation
1424 Because Perl 5 does not have a core concept of attributes in classes,
1425 we can only return information about attributes which have been added
1426 via this class's methods. We cannot discover information about
1427 attributes which are defined in terms of "regular" Perl 5 methods.
1431 =item B<< $metaclass->get_attribute($attribute_name) >>
1433 This will return a L<Class::MOP::Attribute> for the specified
1434 C<$attribute_name>. If the class does not have the specified
1435 attribute, it returns C<undef>.
1437 NOTE that get_attribute does not search superclasses, for that you
1438 need to use C<find_attribute_by_name>.
1440 =item B<< $metaclass->has_attribute($attribute_name) >>
1442 Returns a boolean indicating whether or not the class defines the
1443 named attribute. It does not include attributes inherited from parent
1446 =item B<< $metaclass->get_attribute_map >>
1448 Returns a hash reference representing the attributes defined in this
1449 class. The keys are attribute names and the values are
1450 L<Class::MOP::Attribute> objects.
1452 =item B<< $metaclass->get_attribute_list >>
1454 This will return a list of attributes I<names> for all attributes
1455 defined in this class.
1457 =item B<< $metaclass->get_all_attributes >>
1459 This will traverse the inheritance hierarchy and return a list of all
1460 the L<Class::MOP::Attribute> objects for this class and its parents.
1462 =item B<< $metaclass->find_attribute_by_name($attribute_name) >>
1464 This will return a L<Class::MOP::Attribute> for the specified
1465 C<$attribute_name>. If the class does not have the specified
1466 attribute, it returns C<undef>
1468 Unlike C<get_attribute>, this attribute I<will> look for the named
1469 attribute in superclasses.
1471 =item B<< $metaclass->add_attribute(...) >>
1473 This method accepts either an existing L<Class::MOP::Attribute>
1474 object, or parameters suitable for passing to that class's C<new>
1477 The attribute provided will be added to the class.
1479 Any accessor methods defined by the attribute will be added to the
1480 class when the attribute is added.
1482 If an attribute of the same name already exists, the old attribute
1483 will be removed first.
1485 =item B<< $metaclass->remove_attribute($attribute_name) >>
1487 This will remove the named attribute from the class, and
1488 L<Class::MOP::Attribute> object.
1490 Removing an attribute also removes any accessor methods defined by the
1493 However, note that removing an attribute will only affect I<future>
1494 object instances created for this class, not existing instances.
1496 =item B<< $metaclass->attribute_metaclass >>
1498 Returns the class name of the attribute metaclass for this class. By
1499 default, this is L<Class::MOP::Attribute>.
1503 =head2 Class Immutability
1505 Making a class immutable "freezes" the class definition. You can no
1506 longer call methods which alter the class, such as adding or removing
1507 methods or attributes.
1509 Making a class immutable lets us optimize the class by inlining some
1510 methods, and also allows us to optimize some methods on the metaclass
1513 After immutabilization, the metaclass object will cache most
1514 informational methods such as C<get_method_map> and
1515 C<get_all_attributes>. Methods which would alter the class, such as
1516 C<add_attribute>, C<add_method>, and so on will throw an error on an
1517 immutable metaclass object.
1519 The immutabilization system in L<Moose> takes much greater advantage
1520 of the inlining features than Class::MOP itself does.
1524 =item B<< $metaclass->make_immutable(%options) >>
1526 This method will create an immutable transformer and uses it to make
1527 the class and its metaclass object immutable.
1529 This method accepts the following options:
1533 =item * inline_accessors
1535 =item * inline_constructor
1537 =item * inline_destructor
1539 These are all booleans indicating whether the specified method(s)
1542 By default, accessors and the constructor are inlined, but not the
1545 =item * immutable_trait
1547 The name of a class which will be used as a parent class for the
1548 metaclass object being made immutable. This "trait" implements the
1549 post-immutability functionality of the metaclass (but not the
1550 transformation itself).
1552 This defaults to L<Class::MOP::Class::Immutable::Trait>.
1554 =item * constructor_name
1556 This is the constructor method name. This defaults to "new".
1558 =item * constructor_class
1560 The name of the method metaclass for constructors. It will be used to
1561 generate the inlined constructor. This defaults to
1562 "Class::MOP::Method::Constructor".
1564 =item * replace_constructor
1566 This is a boolean indicating whether an existing constructor should be
1567 replaced when inlining a constructor. This defaults to false.
1569 =item * destructor_class
1571 The name of the method metaclass for destructors. It will be used to
1572 generate the inlined destructor. This defaults to
1573 "Class::MOP::Method::Denstructor".
1575 =item * replace_destructor
1577 This is a boolean indicating whether an existing destructor should be
1578 replaced when inlining a destructor. This defaults to false.
1582 =item B<< $metaclass->immutable_options >>
1584 Returns a hash of the options used when making the class immutable, including
1585 both defaults and anything supplied by the user in the call to C<<
1586 $metaclass->make_immutable >>. This is useful if you need to temporarily make
1587 a class mutable and then restore immutability as it was before.
1589 =item B<< $metaclass->make_mutable >>
1591 Calling this method reverse the immutabilization transformation.
1595 =head2 Method Modifiers
1597 Method modifiers are hooks which allow a method to be wrapped with
1598 I<before>, I<after> and I<around> method modifiers. Every time a
1599 method is called, it's modifiers are also called.
1601 A class can modify its own methods, as well as methods defined in
1604 =head3 How method modifiers work?
1606 Method modifiers work by wrapping the original method and then
1607 replacing it in the class's symbol table. The wrappers will handle
1608 calling all the modifiers in the appropriate order and preserving the
1609 calling context for the original method.
1611 The return values of C<before> and C<after> modifiers are
1612 ignored. This is because their purpose is B<not> to filter the input
1613 and output of the primary method (this is done with an I<around>
1616 This may seem like an odd restriction to some, but doing this allows
1617 for simple code to be added at the beginning or end of a method call
1618 without altering the function of the wrapped method or placing any
1619 extra responsibility on the code of the modifier.
1621 Of course if you have more complex needs, you can use the C<around>
1622 modifier which allows you to change both the parameters passed to the
1623 wrapped method, as well as its return value.
1625 Before and around modifiers are called in last-defined-first-called
1626 order, while after modifiers are called in first-defined-first-called
1627 order. So the call tree might looks something like this:
1639 =head3 What is the performance impact?
1641 Of course there is a performance cost associated with method
1642 modifiers, but we have made every effort to make that cost directly
1643 proportional to the number of modifier features you utilize.
1645 The wrapping method does it's best to B<only> do as much work as it
1646 absolutely needs to. In order to do this we have moved some of the
1647 performance costs to set-up time, where they are easier to amortize.
1649 All this said, our benchmarks have indicated the following:
1651 simple wrapper with no modifiers 100% slower
1652 simple wrapper with simple before modifier 400% slower
1653 simple wrapper with simple after modifier 450% slower
1654 simple wrapper with simple around modifier 500-550% slower
1655 simple wrapper with all 3 modifiers 1100% slower
1657 These numbers may seem daunting, but you must remember, every feature
1658 comes with some cost. To put things in perspective, just doing a
1659 simple C<AUTOLOAD> which does nothing but extract the name of the
1660 method called and return it costs about 400% over a normal method
1665 =item B<< $metaclass->add_before_method_modifier($method_name, $code) >>
1667 This wraps the specified method with the supplied subroutine
1668 reference. The modifier will be called as a method itself, and will
1669 receive the same arguments as are passed to the method.
1671 When the modifier exits, the wrapped method will be called.
1673 The return value of the modifier will be ignored.
1675 =item B<< $metaclass->add_after_method_modifier($method_name, $code) >>
1677 This wraps the specified method with the supplied subroutine
1678 reference. The modifier will be called as a method itself, and will
1679 receive the same arguments as are passed to the method.
1681 When the wrapped methods exits, the modifier will be called.
1683 The return value of the modifier will be ignored.
1685 =item B<< $metaclass->add_around_method_modifier($method_name, $code) >>
1687 This wraps the specified method with the supplied subroutine
1690 The first argument passed to the modifier will be a subroutine
1691 reference to the wrapped method. The second argument is the object,
1692 and after that come any arguments passed when the method is called.
1694 The around modifier can choose to call the original method, as well as
1695 what arguments to pass if it does so.
1697 The return value of the modifier is what will be seen by the caller.
1701 =head2 Introspection
1705 =item B<< Class::MOP::Class->meta >>
1707 This will return a L<Class::MOP::Class> instance for this class.
1709 It should also be noted that L<Class::MOP> will actually bootstrap
1710 this module by installing a number of attribute meta-objects into its
1717 Stevan Little E<lt>stevan@iinteractive.comE<gt>
1719 =head1 COPYRIGHT AND LICENSE
1721 Copyright 2006-2009 by Infinity Interactive, Inc.
1723 L<http://www.iinteractive.com>
1725 This library is free software; you can redistribute it and/or modify
1726 it under the same terms as Perl itself.