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', 'weaken';
14 use Sub::Name 'subname';
15 use Devel::GlobalDestruction 'in_global_destruction';
17 our $VERSION = '0.89';
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 (defined $package_name && $package_name && !ref($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 sub construct_class_instance {
45 Carp::cluck('The construct_class_instance method has been made private.'
46 . " The public version is deprecated and will be removed in a future release.\n");
47 shift->_construct_class_instance(@_);
50 # NOTE: (meta-circularity)
51 # this is a special form of _construct_instance
52 # (see below), which is used to construct class
53 # meta-object instances for any Class::MOP::*
54 # class. All other classes will use the more
55 # normal &construct_instance.
56 sub _construct_class_instance {
58 my $options = @_ == 1 ? $_[0] : {@_};
59 my $package_name = $options->{package};
60 (defined $package_name && $package_name)
61 || confess "You must pass a package name";
63 # return the metaclass if we have it cached,
64 # and it is still defined (it has not been
65 # reaped by DESTROY yet, which can happen
66 # annoyingly enough during global destruction)
68 if (defined(my $meta = Class::MOP::get_metaclass_by_name($package_name))) {
73 # we need to deal with the possibility
74 # of class immutability here, and then
75 # get the name of the class appropriately
77 ? ($class->is_immutable
78 ? $class->get_mutable_metaclass_name()
82 # now create the metaclass
84 if ($class eq 'Class::MOP::Class') {
85 $meta = $class->_new($options);
89 # it is safe to use meta here because
90 # class will always be a subclass of
91 # Class::MOP::Class, which defines meta
92 $meta = $class->meta->_construct_instance($options)
95 # and check the metaclass compatibility
96 $meta->_check_metaclass_compatibility();
98 Class::MOP::store_metaclass_by_name($package_name, $meta);
101 # we need to weaken any anon classes
102 # so that they can call DESTROY properly
103 Class::MOP::weaken_metaclass($package_name) if $meta->is_anon_class;
110 my $options = @_ == 1 ? $_[0] : {@_};
113 # inherited from Class::MOP::Package
114 'package' => $options->{package},
117 # since the following attributes will
118 # actually be loaded from the symbol
119 # table, and actually bypass the instance
120 # entirely, we can just leave these things
121 # listed here for reference, because they
122 # should not actually have a value associated
124 'namespace' => \undef,
126 # inherited from Class::MOP::Module
128 'authority' => \undef,
130 # defined in Class::MOP::Class
131 'superclasses' => \undef,
135 'attribute_metaclass' =>
136 ( $options->{'attribute_metaclass'} || 'Class::MOP::Attribute' ),
137 'method_metaclass' =>
138 ( $options->{'method_metaclass'} || 'Class::MOP::Method' ),
139 'wrapped_method_metaclass' => (
140 $options->{'wrapped_method_metaclass'}
141 || 'Class::MOP::Method::Wrapped'
143 'instance_metaclass' =>
144 ( $options->{'instance_metaclass'} || 'Class::MOP::Instance' ),
145 'immutable_trait' => (
146 $options->{'immutable_trait'}
147 || 'Class::MOP::Class::Immutable::Trait'
149 'constructor_name' => ( $options->{constructor_name} || 'new' ),
150 'constructor_class' => (
151 $options->{constructor_class} || 'Class::MOP::Method::Constructor'
153 'destructor_class' => $options->{destructor_class},
157 sub reset_package_cache_flag { (shift)->{'_package_cache_flag'} = undef }
158 sub update_package_cache_flag {
161 # we can manually update the cache number
162 # since we are actually adding the method
163 # to our cache as well. This avoids us
164 # having to regenerate the method_map.
166 $self->{'_package_cache_flag'} = Class::MOP::check_package_cache_flag($self->name);
170 sub check_metaclass_compatibility {
171 Carp::cluck('The check_metaclass_compatibility method has been made private.'
172 . " The public version is deprecated and will be removed in a future release.\n");
173 shift->_check_metaclass_compatibility(@_);
176 sub _check_metaclass_compatibility {
179 # this is always okay ...
180 return if ref($self) eq 'Class::MOP::Class' &&
181 $self->instance_metaclass eq 'Class::MOP::Instance';
183 my @class_list = $self->linearized_isa;
184 shift @class_list; # shift off $self->name
186 foreach my $superclass_name (@class_list) {
187 my $super_meta = Class::MOP::get_metaclass_by_name($superclass_name) || next;
190 # we need to deal with the possibility
191 # of class immutability here, and then
192 # get the name of the class appropriately
194 = $super_meta->is_immutable
195 ? $super_meta->get_mutable_metaclass_name()
198 ($self->isa($super_meta_type))
199 || confess "The metaclass of " . $self->name . " ("
200 . (ref($self)) . ")" . " is not compatible with the " .
201 "metaclass of its superclass, ".$superclass_name . " ("
202 . ($super_meta_type) . ")";
204 # we also need to check that instance metaclasses
205 # are compatibile in the same the class.
206 ($self->instance_metaclass->isa($super_meta->instance_metaclass))
207 || confess "The instance metaclass for " . $self->name . " (" . ($self->instance_metaclass) . ")" .
208 " is not compatible with the " .
209 "instance metaclass of its superclass, " . $superclass_name . " (" . ($super_meta->instance_metaclass) . ")";
217 # this should be sufficient, if you have a
218 # use case where it is not, write a test and
220 my $ANON_CLASS_SERIAL = 0;
223 # we need a sufficiently annoying prefix
224 # this should suffice for now, this is
225 # used in a couple of places below, so
226 # need to put it up here for now.
227 my $ANON_CLASS_PREFIX = 'Class::MOP::Class::__ANON__::SERIAL::';
231 no warnings 'uninitialized';
232 $self->name =~ /^$ANON_CLASS_PREFIX/;
235 sub create_anon_class {
236 my ($class, %options) = @_;
237 my $package_name = $ANON_CLASS_PREFIX . ++$ANON_CLASS_SERIAL;
238 return $class->create($package_name, %options);
242 # this will only get called for
243 # anon-classes, all other calls
244 # are assumed to occur during
245 # global destruction and so don't
246 # really need to be handled explicitly
250 return if in_global_destruction(); # it'll happen soon anyway and this just makes things more complicated
252 no warnings 'uninitialized';
253 my $name = $self->name;
254 return unless $name =~ /^$ANON_CLASS_PREFIX/;
255 # Moose does a weird thing where it replaces the metaclass for
256 # class when fixing metaclass incompatibility. In that case,
257 # we don't want to clean out the namespace now. We can detect
258 # that because Moose will explicitly update the singleton
259 # cache in Class::MOP.
260 my $current_meta = Class::MOP::get_metaclass_by_name($name);
261 return if $current_meta ne $self;
263 my ($serial_id) = ($name =~ /^$ANON_CLASS_PREFIX(\d+)/);
265 @{$name . '::ISA'} = ();
266 %{$name . '::'} = ();
267 delete ${$ANON_CLASS_PREFIX}{$serial_id . '::'};
269 Class::MOP::remove_metaclass_by_name($name);
274 # creating classes with MOP ...
277 my ( $class, @args ) = @_;
279 unshift @args, 'package' if @args % 2 == 1;
281 my (%options) = @args;
282 my $package_name = $options{package};
284 (ref $options{superclasses} eq 'ARRAY')
285 || confess "You must pass an ARRAY ref of superclasses"
286 if exists $options{superclasses};
288 (ref $options{attributes} eq 'ARRAY')
289 || confess "You must pass an ARRAY ref of attributes"
290 if exists $options{attributes};
292 (ref $options{methods} eq 'HASH')
293 || confess "You must pass a HASH ref of methods"
294 if exists $options{methods};
296 my (%initialize_options) = @args;
297 delete @initialize_options{qw(
305 my $meta = $class->initialize( $package_name => %initialize_options );
307 $meta->_instantiate_module( $options{version}, $options{authority} );
310 $meta->add_method('meta' => sub {
311 $class->initialize(ref($_[0]) || $_[0]);
314 $meta->superclasses(@{$options{superclasses}})
315 if exists $options{superclasses};
317 # process attributes first, so that they can
318 # install accessors, but locally defined methods
319 # can then overwrite them. It is maybe a little odd, but
320 # I think this should be the order of things.
321 if (exists $options{attributes}) {
322 foreach my $attr (@{$options{attributes}}) {
323 $meta->add_attribute($attr);
326 if (exists $options{methods}) {
327 foreach my $method_name (keys %{$options{methods}}) {
328 $meta->add_method($method_name, $options{methods}->{$method_name});
337 # all these attribute readers will be bootstrapped
338 # away in the Class::MOP bootstrap section
340 sub get_attribute_map { $_[0]->{'attributes'} }
341 sub attribute_metaclass { $_[0]->{'attribute_metaclass'} }
342 sub instance_metaclass { $_[0]->{'instance_metaclass'} }
343 sub immutable_trait { $_[0]->{'immutable_trait'} }
344 sub constructor_class { $_[0]->{'constructor_class'} }
345 sub constructor_name { $_[0]->{'constructor_name'} }
346 sub destructor_class { $_[0]->{'destructor_class'} }
348 # Instance Construction & Cloning
354 # we need to protect the integrity of the
355 # Class::MOP::Class singletons here, so we
356 # delegate this to &construct_class_instance
357 # which will deal with the singletons
358 return $class->_construct_class_instance(@_)
359 if $class->name->isa('Class::MOP::Class');
360 return $class->_construct_instance(@_);
363 sub construct_instance {
364 Carp::cluck('The construct_instance method has been made private.'
365 . " The public version is deprecated and will be removed in a future release.\n");
366 shift->_construct_instance(@_);
369 sub _construct_instance {
371 my $params = @_ == 1 ? $_[0] : {@_};
372 my $meta_instance = $class->get_meta_instance();
374 # the code below is almost certainly incorrect
375 # but this is foreign inheritance, so we might
376 # have to kludge it in the end.
377 my $instance = $params->{__INSTANCE__} || $meta_instance->create_instance();
378 foreach my $attr ($class->get_all_attributes()) {
379 $attr->initialize_instance_slot($meta_instance, $instance, $params);
382 # this will only work for a HASH instance type
383 if ($class->is_anon_class) {
384 (Scalar::Util::reftype($instance) eq 'HASH')
385 || confess "Currently only HASH based instances are supported with instance of anon-classes";
387 # At some point we should make this official
388 # as a reserved slot name, but right now I am
389 # going to keep it here.
390 # my $RESERVED_MOP_SLOT = '__MOP__';
391 $instance->{'__MOP__'} = $class;
397 sub get_meta_instance {
399 $self->{'_meta_instance'} ||= $self->_create_meta_instance();
402 sub create_meta_instance {
403 Carp::cluck('The create_meta_instance method has been made private.'
404 . " The public version is deprecated and will be removed in a future release.\n");
405 shift->_create_meta_instance(@_);
408 sub _create_meta_instance {
411 my $instance = $self->instance_metaclass->new(
412 associated_metaclass => $self,
413 attributes => [ $self->get_all_attributes() ],
416 $self->add_meta_instance_dependencies()
417 if $instance->is_dependent_on_superclasses();
424 my $instance = shift;
425 (blessed($instance) && $instance->isa($class->name))
426 || confess "You must pass an instance of the metaclass (" . (ref $class ? $class->name : $class) . "), not ($instance)";
429 # we need to protect the integrity of the
430 # Class::MOP::Class singletons here, they
431 # should not be cloned.
432 return $instance if $instance->isa('Class::MOP::Class');
433 $class->_clone_instance($instance, @_);
437 Carp::cluck('The clone_instance method has been made private.'
438 . " The public version is deprecated and will be removed in a future release.\n");
439 shift->_clone_instance(@_);
442 sub _clone_instance {
443 my ($class, $instance, %params) = @_;
445 || confess "You can only clone instances, ($instance) is not a blessed instance";
446 my $meta_instance = $class->get_meta_instance();
447 my $clone = $meta_instance->clone_instance($instance);
448 foreach my $attr ($class->get_all_attributes()) {
449 if ( defined( my $init_arg = $attr->init_arg ) ) {
450 if (exists $params{$init_arg}) {
451 $attr->set_value($clone, $params{$init_arg});
458 sub rebless_instance {
459 my ($self, $instance, %params) = @_;
461 my $old_metaclass = Class::MOP::class_of($instance);
463 my $old_class = $old_metaclass ? $old_metaclass->name : blessed($instance);
464 $self->name->isa($old_class)
465 || confess "You may rebless only into a subclass of ($old_class), of which (". $self->name .") isn't.";
467 $old_metaclass->rebless_instance_away($instance, $self, %params)
470 my $meta_instance = $self->get_meta_instance();
473 # we use $_[1] here because of t/306_rebless_overload.t regressions on 5.8.8
474 $meta_instance->rebless_instance_structure($_[1], $self);
476 foreach my $attr ( $self->get_all_attributes ) {
477 if ( $attr->has_value($instance) ) {
478 if ( defined( my $init_arg = $attr->init_arg ) ) {
479 $params{$init_arg} = $attr->get_value($instance)
480 unless exists $params{$init_arg};
483 $attr->set_value($instance, $attr->get_value($instance));
488 foreach my $attr ($self->get_all_attributes) {
489 $attr->initialize_instance_slot($meta_instance, $instance, \%params);
495 sub rebless_instance_away {
496 # this intentionally does nothing, it is just a hook
503 my $var_spec = { sigil => '@', type => 'ARRAY', name => 'ISA' };
506 @{$self->get_package_symbol($var_spec)} = @supers;
509 # on 5.8 and below, we need to call
510 # a method to get Perl to detect
511 # a cycle in the class hierarchy
512 my $class = $self->name;
516 # we need to check the metaclass
517 # compatibility here so that we can
518 # be sure that the superclass is
519 # not potentially creating an issues
520 # we don't know about
522 $self->_check_metaclass_compatibility();
523 $self->_superclasses_updated();
525 @{$self->get_package_symbol($var_spec)};
528 sub _superclasses_updated {
530 $self->update_meta_instance_dependencies();
535 my $super_class = $self->name;
537 return @{ $super_class->mro::get_isarev() };
540 sub direct_subclasses {
542 my $super_class = $self->name;
547 } Class::MOP::Class->initialize($_)->superclasses
552 return @{ mro::get_linear_isa( (shift)->name ) };
555 sub class_precedence_list {
557 my $name = $self->name;
559 unless (Class::MOP::IS_RUNNING_ON_5_10()) {
561 # We need to check for circular inheritance here
562 # if we are are not on 5.10, cause 5.8 detects it
563 # late. This will do nothing if all is well, and
564 # blow up otherwise. Yes, it's an ugly hack, better
565 # suggestions are welcome.
567 ($name || return)->isa('This is a test for circular inheritance')
570 # if our mro is c3, we can
571 # just grab the linear_isa
572 if (mro::get_mro($name) eq 'c3') {
573 return @{ mro::get_linear_isa($name) }
577 # we can't grab the linear_isa for dfs
578 # since it has all the duplicates
583 $self->initialize($_)->class_precedence_list()
584 } $self->superclasses()
592 my $fetch_and_prepare_method = sub {
593 my ($self, $method_name) = @_;
594 my $wrapped_metaclass = $self->wrapped_method_metaclass;
596 my $method = $self->get_method($method_name);
597 # if we dont have local ...
599 # try to find the next method
600 $method = $self->find_next_method_by_name($method_name);
601 # die if it does not exist
603 || confess "The method '$method_name' was not found in the inheritance hierarchy for " . $self->name;
604 # and now make sure to wrap it
605 # even if it is already wrapped
606 # because we need a new sub ref
607 $method = $wrapped_metaclass->wrap($method);
610 # now make sure we wrap it properly
611 $method = $wrapped_metaclass->wrap($method)
612 unless $method->isa($wrapped_metaclass);
614 $self->add_method($method_name => $method);
618 sub add_before_method_modifier {
619 my ($self, $method_name, $method_modifier) = @_;
620 (defined $method_name && $method_name)
621 || confess "You must pass in a method name";
622 my $method = $fetch_and_prepare_method->($self, $method_name);
623 $method->add_before_modifier(
624 subname(':before' => $method_modifier)
628 sub add_after_method_modifier {
629 my ($self, $method_name, $method_modifier) = @_;
630 (defined $method_name && $method_name)
631 || confess "You must pass in a method name";
632 my $method = $fetch_and_prepare_method->($self, $method_name);
633 $method->add_after_modifier(
634 subname(':after' => $method_modifier)
638 sub add_around_method_modifier {
639 my ($self, $method_name, $method_modifier) = @_;
640 (defined $method_name && $method_name)
641 || confess "You must pass in a method name";
642 my $method = $fetch_and_prepare_method->($self, $method_name);
643 $method->add_around_modifier(
644 subname(':around' => $method_modifier)
649 # the methods above used to be named like this:
650 # ${pkg}::${method}:(before|after|around)
651 # but this proved problematic when using one modifier
652 # to wrap multiple methods (something which is likely
653 # to happen pretty regularly IMO). So instead of naming
654 # it like this, I have chosen to just name them purely
655 # with their modifier names, like so:
656 # :(before|after|around)
657 # The fact is that in a stack trace, it will be fairly
658 # evident from the context what method they are attached
659 # to, and so don't need the fully qualified name.
663 Carp::cluck("The alias_method method is deprecated. Use add_method instead.\n");
665 shift->add_method(@_);
668 sub find_method_by_name {
669 my ($self, $method_name) = @_;
670 (defined $method_name && $method_name)
671 || confess "You must define a method name to find";
672 foreach my $class ($self->linearized_isa) {
673 # fetch the meta-class ...
674 my $meta = $self->initialize($class);
675 return $meta->get_method($method_name)
676 if $meta->has_method($method_name);
681 sub get_all_methods {
683 my %methods = map { %{ $self->initialize($_)->get_method_map } } reverse $self->linearized_isa;
684 return values %methods;
687 sub compute_all_applicable_methods {
688 Carp::cluck('The compute_all_applicable_methods method is deprecated.'
689 . " Use get_all_methods instead.\n");
694 class => $_->package_name,
695 code => $_, # sigh, overloading
697 } shift->get_all_methods(@_);
700 sub get_all_method_names {
703 grep { $uniq{$_}++ == 0 } map { $_->name } $self->get_all_methods;
706 sub find_all_methods_by_name {
707 my ($self, $method_name) = @_;
708 (defined $method_name && $method_name)
709 || confess "You must define a method name to find";
711 foreach my $class ($self->linearized_isa) {
712 # fetch the meta-class ...
713 my $meta = $self->initialize($class);
715 name => $method_name,
717 code => $meta->get_method($method_name)
718 } if $meta->has_method($method_name);
723 sub find_next_method_by_name {
724 my ($self, $method_name) = @_;
725 (defined $method_name && $method_name)
726 || confess "You must define a method name to find";
727 my @cpl = $self->linearized_isa;
728 shift @cpl; # discard ourselves
729 foreach my $class (@cpl) {
730 # fetch the meta-class ...
731 my $meta = $self->initialize($class);
732 return $meta->get_method($method_name)
733 if $meta->has_method($method_name);
742 # either we have an attribute object already
743 # or we need to create one from the args provided
744 my $attribute = blessed($_[0]) ? $_[0] : $self->attribute_metaclass->new(@_);
745 # make sure it is derived from the correct type though
746 ($attribute->isa('Class::MOP::Attribute'))
747 || confess "Your attribute must be an instance of Class::MOP::Attribute (or a subclass)";
749 # first we attach our new attribute
750 # because it might need certain information
751 # about the class which it is attached to
752 $attribute->attach_to_class($self);
754 my $attr_name = $attribute->name;
756 # then we remove attributes of a conflicting
757 # name here so that we can properly detach
758 # the old attr object, and remove any
759 # accessors it would have generated
760 if ( $self->has_attribute($attr_name) ) {
761 $self->remove_attribute($attr_name);
763 $self->invalidate_meta_instances();
766 # get our count of previously inserted attributes and
767 # increment by one so this attribute knows its order
768 my $order = (scalar keys %{$self->get_attribute_map});
769 $attribute->_set_insertion_order($order);
771 # then onto installing the new accessors
772 $self->get_attribute_map->{$attr_name} = $attribute;
774 # invalidate package flag here
778 eval { $attribute->install_accessors() };
782 $self->remove_attribute($attr_name);
789 sub update_meta_instance_dependencies {
792 if ( $self->{meta_instance_dependencies} ) {
793 return $self->add_meta_instance_dependencies;
797 sub add_meta_instance_dependencies {
800 $self->remove_meta_instance_dependencies;
802 my @attrs = $self->get_all_attributes();
805 my @classes = grep { not $seen{$_->name}++ } map { $_->associated_class } @attrs;
807 foreach my $class ( @classes ) {
808 $class->add_dependent_meta_instance($self);
811 $self->{meta_instance_dependencies} = \@classes;
814 sub remove_meta_instance_dependencies {
817 if ( my $classes = delete $self->{meta_instance_dependencies} ) {
818 foreach my $class ( @$classes ) {
819 $class->remove_dependent_meta_instance($self);
829 sub add_dependent_meta_instance {
830 my ( $self, $metaclass ) = @_;
831 push @{ $self->{dependent_meta_instances} }, $metaclass;
834 sub remove_dependent_meta_instance {
835 my ( $self, $metaclass ) = @_;
836 my $name = $metaclass->name;
837 @$_ = grep { $_->name ne $name } @$_ for $self->{dependent_meta_instances};
840 sub invalidate_meta_instances {
842 $_->invalidate_meta_instance() for $self, @{ $self->{dependent_meta_instances} };
845 sub invalidate_meta_instance {
847 undef $self->{_meta_instance};
851 my ($self, $attribute_name) = @_;
852 (defined $attribute_name && $attribute_name)
853 || confess "You must define an attribute name";
854 exists $self->get_attribute_map->{$attribute_name};
858 my ($self, $attribute_name) = @_;
859 (defined $attribute_name && $attribute_name)
860 || confess "You must define an attribute name";
861 return $self->get_attribute_map->{$attribute_name}
863 # this will return undef anyway, so no need ...
864 # if $self->has_attribute($attribute_name);
868 sub remove_attribute {
869 my ($self, $attribute_name) = @_;
870 (defined $attribute_name && $attribute_name)
871 || confess "You must define an attribute name";
872 my $removed_attribute = $self->get_attribute_map->{$attribute_name};
873 return unless defined $removed_attribute;
874 delete $self->get_attribute_map->{$attribute_name};
875 $self->invalidate_meta_instances();
876 $removed_attribute->remove_accessors();
877 $removed_attribute->detach_from_class();
878 return $removed_attribute;
881 sub get_attribute_list {
883 keys %{$self->get_attribute_map};
886 sub get_all_attributes {
888 my %attrs = map { %{ $self->initialize($_)->get_attribute_map } } reverse $self->linearized_isa;
889 return values %attrs;
892 sub compute_all_applicable_attributes {
893 Carp::cluck('The compute_all_applicable_attributes method has been deprecated.'
894 . " Use get_all_attributes instead.\n");
896 shift->get_all_attributes(@_);
899 sub find_attribute_by_name {
900 my ($self, $attr_name) = @_;
901 foreach my $class ($self->linearized_isa) {
902 # fetch the meta-class ...
903 my $meta = $self->initialize($class);
904 return $meta->get_attribute($attr_name)
905 if $meta->has_attribute($attr_name);
910 # check if we can reinitialize
914 # if any local attr is defined
915 return if $self->get_attribute_list;
917 # or any non-declared methods
918 if ( my @methods = values %{ $self->get_method_map } ) {
919 my $metaclass = $self->method_metaclass;
920 foreach my $method ( @methods ) {
921 return if $method->isa("Class::MOP::Method::Generated");
922 # FIXME do we need to enforce this too? return unless $method->isa($metaclass);
932 sub is_immutable { 0 }
934 sub _immutable_options {
935 my ( $self, @args ) = @_;
938 inline_accessors => 1,
939 inline_constructor => 1,
940 inline_destructor => 0,
942 immutable_trait => $self->immutable_trait,
943 constructor_name => $self->constructor_name,
944 constructor_class => $self->constructor_class,
945 destructor_class => $self->destructor_class,
951 my ( $self, @args ) = @_;
953 if ( $self->is_mutable ) {
954 $self->_initialize_immutable( $self->_immutable_options(@args) );
955 $self->_rebless_as_immutable(@args);
966 if ( $self->is_immutable ) {
967 my @args = $self->immutable_options;
968 $self->_rebless_as_mutable();
969 $self->_remove_inlined_code(@args);
970 delete $self->{__immutable};
978 sub _rebless_as_immutable {
979 my ( $self, @args ) = @_;
981 $self->{__immutable}{original_class} = ref $self;
983 bless $self => $self->_immutable_metaclass(@args);
986 sub _immutable_metaclass {
987 my ( $self, %args ) = @_;
989 if ( my $class = $args{immutable_metaclass} ) {
993 my $trait = $args{immutable_trait} = $self->immutable_trait
994 || confess "no immutable trait specified for $self";
996 my $meta_attr = $self->meta->find_attribute_by_name("immutable_trait");
1000 if ( $meta_attr and $trait eq $meta_attr->default ) {
1001 # if the trait is the same as the default we try and pick a
1002 # predictable name for the immutable metaclass
1003 $class_name = 'Class::MOP::Class::Immutable::' . ref($self);
1006 $class_name = join '::', 'Class::MOP::Class::Immutable::CustomTrait',
1007 $trait, 'ForMetaClass', ref($self);
1011 if Class::MOP::is_class_loaded($class_name);
1013 # If the metaclass is a subclass of CMOP::Class which has had
1014 # metaclass roles applied (via Moose), then we want to make sure
1015 # that we preserve that anonymous class (see Fey::ORM for an
1016 # example of where this matters).
1018 = $self->meta->is_immutable
1019 ? $self->meta->get_mutable_metaclass_name
1022 my $meta = $meta_name->create(
1024 superclasses => [ ref $self ],
1027 Class::MOP::load_class($trait);
1028 for my $meth ( Class::MOP::Class->initialize($trait)->get_all_methods ) {
1029 next if $meta->has_method( $meth->name );
1031 if ( $meta->find_method_by_name( $meth->name ) ) {
1032 $meta->add_around_method_modifier( $meth->name, $meth->body );
1035 $meta->add_method( $meth->name, $meth->clone );
1039 $meta->make_immutable( inline_constructor => 0 );
1044 sub _remove_inlined_code {
1047 $self->remove_method( $_->name ) for $self->_inlined_methods;
1049 delete $self->{__immutable}{inlined_methods};
1052 sub _inlined_methods { @{ $_[0]{__immutable}{inlined_methods} || [] } }
1054 sub _add_inlined_method {
1055 my ( $self, $method ) = @_;
1057 push @{ $self->{__immutable}{inlined_methods} ||= [] }, $method;
1060 sub _initialize_immutable {
1061 my ( $self, %args ) = @_;
1063 $self->{__immutable}{options} = \%args;
1064 $self->_install_inlined_code(%args);
1067 sub _install_inlined_code {
1068 my ( $self, %args ) = @_;
1071 $self->_inline_accessors(%args) if $args{inline_accessors};
1072 $self->_inline_constructor(%args) if $args{inline_constructor};
1073 $self->_inline_destructor(%args) if $args{inline_destructor};
1076 sub _rebless_as_mutable {
1079 bless $self, $self->get_mutable_metaclass_name;
1084 sub _inline_accessors {
1087 foreach my $attr_name ( $self->get_attribute_list ) {
1088 $self->get_attribute($attr_name)->install_accessors(1);
1092 sub _inline_constructor {
1093 my ( $self, %args ) = @_;
1095 my $name = $args{constructor_name};
1097 if ( $self->has_method($name) && !$args{replace_constructor} ) {
1098 my $class = $self->name;
1099 warn "Not inlining a constructor for $class since it defines"
1100 . " its own constructor.\n"
1101 . "If you are certain you don't need to inline your"
1102 . " constructor, specify inline_constructor => 0 in your"
1103 . " call to $class->meta->make_immutable\n";
1107 my $constructor_class = $args{constructor_class};
1109 Class::MOP::load_class($constructor_class);
1111 my $constructor = $constructor_class->new(
1115 package_name => $self->name,
1119 if ( $args{replace_constructor} or $constructor->can_be_inlined ) {
1120 $self->add_method( $name => $constructor );
1121 $self->_add_inlined_method($constructor);
1125 sub _inline_destructor {
1126 my ( $self, %args ) = @_;
1128 ( exists $args{destructor_class} && defined $args{destructor_class} )
1129 || confess "The 'inline_destructor' option is present, but "
1130 . "no destructor class was specified";
1132 if ( $self->has_method('DESTROY') && ! $args{replace_destructor} ) {
1133 my $class = $self->name;
1134 warn "Not inlining a destructor for $class since it defines"
1135 . " its own destructor.\n";
1139 my $destructor_class = $args{destructor_class};
1141 Class::MOP::load_class($destructor_class);
1143 return unless $destructor_class->is_needed($self);
1145 my $destructor = $destructor_class->new(
1148 package_name => $self->name,
1152 if ( $args{replace_destructor} or $destructor->can_be_inlined ) {
1153 $self->add_method( 'DESTROY' => $destructor );
1154 $self->_add_inlined_method($destructor);
1166 Class::MOP::Class - Class Meta Object
1170 # assuming that class Foo
1171 # has been defined, you can
1173 # use this for introspection ...
1175 # add a method to Foo ...
1176 Foo->meta->add_method( 'bar' => sub {...} )
1178 # get a list of all the classes searched
1179 # the method dispatcher in the correct order
1180 Foo->meta->class_precedence_list()
1182 # remove a method from Foo
1183 Foo->meta->remove_method('bar');
1185 # or use this to actually create classes ...
1187 Class::MOP::Class->create(
1190 superclasses => ['Foo'],
1192 Class::MOP::Attribute->new('$bar'),
1193 Class::MOP::Attribute->new('$baz'),
1196 calculate_bar => sub {...},
1197 construct_baz => sub {...}
1204 The Class Protocol is the largest and most complex part of the
1205 Class::MOP meta-object protocol. It controls the introspection and
1206 manipulation of Perl 5 classes, and it can create them as well. The
1207 best way to understand what this module can do, is to read the
1208 documentation for each of its methods.
1212 C<Class::MOP::Class> is a subclass of L<Class::MOP::Module>.
1216 =head2 Class construction
1218 These methods all create new C<Class::MOP::Class> objects. These
1219 objects can represent existing classes, or they can be used to create
1220 new classes from scratch.
1222 The metaclass object for a given class is a singleton. If you attempt
1223 to create a metaclass for the same class twice, you will just get the
1228 =item B<< Class::MOP::Class->create($package_name, %options) >>
1230 This method creates a new C<Class::MOP::Class> object with the given
1231 package name. It accepts a number of options.
1237 An optional version number for the newly created package.
1241 An optional authority for the newly created package.
1243 =item * superclasses
1245 An optional array reference of superclass names.
1249 An optional hash reference of methods for the class. The keys of the
1250 hash reference are method names, and values are subroutine references.
1254 An optional array reference of L<Class::MOP::Attribute> objects.
1258 =item B<< Class::MOP::Class->create_anon_class(%options) >>
1260 This method works just like C<< Class::MOP::Class->create >> but it
1261 creates an "anonymous" class. In fact, the class does have a name, but
1262 that name is a unique name generated internally by this module.
1264 It accepts the same C<superclasses>, C<methods>, and C<attributes>
1265 parameters that C<create> accepts.
1267 Anonymous classes are destroyed once the metaclass they are attached
1268 to goes out of scope, and will be removed from Perl's internal symbol
1271 All instances of an anonymous class keep a special reference to the
1272 metaclass object, which prevents the metaclass from going out of scope
1273 while any instances exist.
1275 This only works if the instance if based on a hash reference, however.
1277 =item B<< Class::MOP::Class->initialize($package_name, %options) >>
1279 This method will initialize a C<Class::MOP::Class> object for the
1280 named package. Unlike C<create>, this method I<will not> create a new
1283 The purpose of this method is to retrieve a C<Class::MOP::Class>
1284 object for introspecting an existing class.
1286 If an existing C<Class::MOP::Class> object exists for the named
1287 package, it will be returned, and any options provided will be
1290 If the object does not yet exist, it will be created.
1292 The valid options that can be passed to this method are
1293 C<attribute_metaclass>, C<method_metaclass>,
1294 C<wrapped_method_metaclass>, and C<instance_metaclass>. These are all
1295 optional, and default to the appropriate class in the C<Class::MOP>
1300 =head2 Object instance construction and cloning
1302 These methods are all related to creating and/or cloning object
1307 =item B<< $metaclass->clone_object($instance, %params) >>
1309 This method clones an existing object instance. Any parameters you
1310 provide are will override existing attribute values in the object.
1312 This is a convenience method for cloning an object instance, then
1313 blessing it into the appropriate package.
1315 You could implement a clone method in your class, using this method:
1318 my ($self, %params) = @_;
1319 $self->meta->clone_object($self, %params);
1322 =item B<< $metaclass->rebless_instance($instance, %params) >>
1324 This method changes the class of C<$instance> to the metaclass's class.
1326 You can only rebless an instance into a subclass of its current
1327 class. If you pass any additional parameters, these will be treated
1328 like constructor parameters and used to initialize the object's
1329 attributes. Any existing attributes that are already set will be
1332 Before reblessing the instance, this method will call
1333 C<rebless_instance_away> on the instance's current metaclass. This method
1334 will be passed the instance, the new metaclass, and any parameters
1335 specified to C<rebless_instance>. By default, C<rebless_instance_away>
1336 does nothing; it is merely a hook.
1338 =item B<< $metaclass->new_object(%params) >>
1340 This method is used to create a new object of the metaclass's
1341 class. Any parameters you provide are used to initialize the
1342 instance's attributes. A special C<__INSTANCE__> key can be passed to
1343 provide an already generated instance, rather than having Class::MOP
1344 generate it for you. This is mostly useful for using Class::MOP with
1345 foreign classes, which generally generate instances using their own
1348 =item B<< $metaclass->instance_metaclass >>
1350 Returns the class name of the instance metaclass, see
1351 L<Class::MOP::Instance> for more information on the instance
1354 =item B<< $metaclass->get_meta_instance >>
1356 Returns an instance of the C<instance_metaclass> to be used in the
1357 construction of a new instance of the class.
1361 =head2 Informational predicates
1363 These are a few predicate methods for asking information about the
1368 =item B<< $metaclass->is_anon_class >>
1370 This returns true if the class was created by calling C<<
1371 Class::MOP::Class->create_anon_class >>.
1373 =item B<< $metaclass->is_mutable >>
1375 This returns true if the class is still mutable.
1377 =item B<< $metaclass->is_immutable >>
1379 This returns true if the class has been made immutable.
1381 =item B<< $metaclass->is_pristine >>
1383 A class is I<not> pristine if it has non-inherited attributes or if it
1384 has any generated methods.
1388 =head2 Inheritance Relationships
1392 =item B<< $metaclass->superclasses(@superclasses) >>
1394 This is a read-write accessor which represents the superclass
1395 relationships of the metaclass's class.
1397 This is basically sugar around getting and setting C<@ISA>.
1399 =item B<< $metaclass->class_precedence_list >>
1401 This returns a list of all of the class's ancestor classes. The
1402 classes are returned in method dispatch order.
1404 =item B<< $metaclass->linearized_isa >>
1406 This returns a list based on C<class_precedence_list> but with all
1409 =item B<< $metaclass->subclasses >>
1411 This returns a list of all subclasses for this class, even indirect
1414 =item B<< $metaclass->direct_subclasses >>
1416 This returns a list of immediate subclasses for this class, which does not
1417 include indirect subclasses.
1421 =head2 Method introspection
1423 See L<Class::MOP::Package/Method introspection and creation> for
1424 methods that operate only on the current class. Class::MOP::Class adds
1425 introspection capabilities that take inheritance into account.
1429 =item B<< $metaclass->get_all_methods >>
1431 This will traverse the inheritance hierarchy and return a list of all
1432 the L<Class::MOP::Method> objects for this class and its parents.
1434 =item B<< $metaclass->find_method_by_name($method_name) >>
1436 This will return a L<Class::MOP::Method> for the specified
1437 C<$method_name>. If the class does not have the specified method, it
1440 Unlike C<get_method>, this method I<will> look for the named method in
1443 =item B<< $metaclass->get_all_method_names >>
1445 This will return a list of method I<names> for all of this class's
1446 methods, including inherited methods.
1448 =item B<< $metaclass->find_all_methods_by_name($method_name) >>
1450 This method looks for the named method in the class and all of its
1451 parents. It returns every matching method it finds in the inheritance
1452 tree, so it returns a list of methods.
1454 Each method is returned as a hash reference with three keys. The keys
1455 are C<name>, C<class>, and C<code>. The C<code> key has a
1456 L<Class::MOP::Method> object as its value.
1458 The list of methods is distinct.
1460 =item B<< $metaclass->find_next_method_by_name($method_name) >>
1462 This method returns the first method in any superclass matching the
1463 given name. It is effectively the method that C<SUPER::$method_name>
1468 =head2 Attribute introspection and creation
1470 Because Perl 5 does not have a core concept of attributes in classes,
1471 we can only return information about attributes which have been added
1472 via this class's methods. We cannot discover information about
1473 attributes which are defined in terms of "regular" Perl 5 methods.
1477 =item B<< $metaclass->get_attribute($attribute_name) >>
1479 This will return a L<Class::MOP::Attribute> for the specified
1480 C<$attribute_name>. If the class does not have the specified
1481 attribute, it returns C<undef>.
1483 NOTE that get_attribute does not search superclasses, for that you
1484 need to use C<find_attribute_by_name>.
1486 =item B<< $metaclass->has_attribute($attribute_name) >>
1488 Returns a boolean indicating whether or not the class defines the
1489 named attribute. It does not include attributes inherited from parent
1492 =item B<< $metaclass->get_attribute_map >>
1494 Returns a hash reference representing the attributes defined in this
1495 class. The keys are attribute names and the values are
1496 L<Class::MOP::Attribute> objects.
1498 =item B<< $metaclass->get_attribute_list >>
1500 This will return a list of attributes I<names> for all attributes
1501 defined in this class.
1503 =item B<< $metaclass->get_all_attributes >>
1505 This will traverse the inheritance hierarchy and return a list of all
1506 the L<Class::MOP::Attribute> objects for this class and its parents.
1508 =item B<< $metaclass->find_attribute_by_name($attribute_name) >>
1510 This will return a L<Class::MOP::Attribute> for the specified
1511 C<$attribute_name>. If the class does not have the specified
1512 attribute, it returns C<undef>
1514 Unlike C<get_attribute>, this attribute I<will> look for the named
1515 attribute in superclasses.
1517 =item B<< $metaclass->add_attribute(...) >>
1519 This method accepts either an existing L<Class::MOP::Attribute>
1520 object, or parameters suitable for passing to that class's C<new>
1523 The attribute provided will be added to the class.
1525 Any accessor methods defined by the attribute will be added to the
1526 class when the attribute is added.
1528 If an attribute of the same name already exists, the old attribute
1529 will be removed first.
1531 =item B<< $metaclass->remove_attribute($attribute_name) >>
1533 This will remove the named attribute from the class, and
1534 L<Class::MOP::Attribute> object.
1536 Removing an attribute also removes any accessor methods defined by the
1539 However, note that removing an attribute will only affect I<future>
1540 object instances created for this class, not existing instances.
1542 =item B<< $metaclass->attribute_metaclass >>
1544 Returns the class name of the attribute metaclass for this class. By
1545 default, this is L<Class::MOP::Attribute>. for more information on
1549 =head2 Class Immutability
1551 Making a class immutable "freezes" the class definition. You can no
1552 longer call methods which alter the class, such as adding or removing
1553 methods or attributes.
1555 Making a class immutable lets us optimize the class by inlining some
1556 methods, and also allows us to optimize some methods on the metaclass
1559 After immutabilization, the metaclass object will cache most
1560 informational methods such as C<get_method_map> and
1561 C<get_all_attributes>. Methods which would alter the class, such as
1562 C<add_attribute>, C<add_method>, and so on will throw an error on an
1563 immutable metaclass object.
1565 The immutabilization system in L<Moose> takes much greater advantage
1566 of the inlining features than Class::MOP itself does.
1570 =item B<< $metaclass->make_immutable(%options) >>
1572 This method will create an immutable transformer and uses it to make
1573 the class and its metaclass object immutable.
1575 This method accepts the following options:
1579 =item * inline_accessors
1581 =item * inline_constructor
1583 =item * inline_destructor
1585 These are all booleans indicating whether the specified method(s)
1588 By default, accessors and the constructor are inlined, but not the
1591 =item * immutable_trait
1593 The name of a class which will be used as a parent class for the
1594 metaclass object being made immutable. This "trait" implements the
1595 post-immutability functionality of the metaclass (but not the
1596 transformation itself).
1598 This defaults to L<Class::MOP::Class::Immutable::Trait>.
1600 =item * constructor_name
1602 This is the constructor method name. This defaults to "new".
1604 =item * constructor_class
1606 The name of the method metaclass for constructors. It will be used to
1607 generate the inlined constructor. This defaults to
1608 "Class::MOP::Method::Constructor".
1610 =item * replace_constructor
1612 This is a boolean indicating whether an existing constructor should be
1613 replaced when inlining a constructor. This defaults to false.
1615 =item * destructor_class
1617 The name of the method metaclass for destructors. It will be used to
1618 generate the inlined destructor. This defaults to
1619 "Class::MOP::Method::Denstructor".
1621 =item * replace_destructor
1623 This is a boolean indicating whether an existing destructor should be
1624 replaced when inlining a destructor. This defaults to false.
1628 =item B<< $metaclass->make_mutable >>
1630 Calling this method reverse the immutabilization transformation.
1634 =head2 Method Modifiers
1636 Method modifiers are hooks which allow a method to be wrapped with
1637 I<before>, I<after> and I<around> method modifiers. Every time a
1638 method is called, it's modifiers are also called.
1640 A class can modify its own methods, as well as methods defined in
1643 =head3 How method modifiers work?
1645 Method modifiers work by wrapping the original method and then
1646 replacing it in the class's symbol table. The wrappers will handle
1647 calling all the modifiers in the appropriate order and preserving the
1648 calling context for the original method.
1650 The return values of C<before> and C<after> modifiers are
1651 ignored. This is because their purpose is B<not> to filter the input
1652 and output of the primary method (this is done with an I<around>
1655 This may seem like an odd restriction to some, but doing this allows
1656 for simple code to be added at the beginning or end of a method call
1657 without altering the function of the wrapped method or placing any
1658 extra responsibility on the code of the modifier.
1660 Of course if you have more complex needs, you can use the C<around>
1661 modifier which allows you to change both the parameters passed to the
1662 wrapped method, as well as its return value.
1664 Before and around modifiers are called in last-defined-first-called
1665 order, while after modifiers are called in first-defined-first-called
1666 order. So the call tree might looks something like this:
1678 =head3 What is the performance impact?
1680 Of course there is a performance cost associated with method
1681 modifiers, but we have made every effort to make that cost directly
1682 proportional to the number of modifier features you utilize.
1684 The wrapping method does it's best to B<only> do as much work as it
1685 absolutely needs to. In order to do this we have moved some of the
1686 performance costs to set-up time, where they are easier to amortize.
1688 All this said, our benchmarks have indicated the following:
1690 simple wrapper with no modifiers 100% slower
1691 simple wrapper with simple before modifier 400% slower
1692 simple wrapper with simple after modifier 450% slower
1693 simple wrapper with simple around modifier 500-550% slower
1694 simple wrapper with all 3 modifiers 1100% slower
1696 These numbers may seem daunting, but you must remember, every feature
1697 comes with some cost. To put things in perspective, just doing a
1698 simple C<AUTOLOAD> which does nothing but extract the name of the
1699 method called and return it costs about 400% over a normal method
1704 =item B<< $metaclass->add_before_method_modifier($method_name, $code) >>
1706 This wraps the specified method with the supplied subroutine
1707 reference. The modifier will be called as a method itself, and will
1708 receive the same arguments as are passed to the method.
1710 When the modifier exits, the wrapped method will be called.
1712 The return value of the modifier will be ignored.
1714 =item B<< $metaclass->add_after_method_modifier($method_name, $code) >>
1716 This wraps the specified method with the supplied subroutine
1717 reference. The modifier will be called as a method itself, and will
1718 receive the same arguments as are passed to the method.
1720 When the wrapped methods exits, the modifier will be called.
1722 The return value of the modifier will be ignored.
1724 =item B<< $metaclass->add_around_method_modifier($method_name, $code) >>
1726 This wraps the specified method with the supplied subroutine
1729 The first argument passed to the modifier will be a subroutine
1730 reference to the wrapped method. The second argument is the object,
1731 and after that come any arguments passed when the method is called.
1733 The around modifier can choose to call the original method, as well as
1734 what arguments to pass if it does so.
1736 The return value of the modifier is what will be seen by the caller.
1740 =head2 Introspection
1744 =item B<< Class::MOP::Class->meta >>
1746 This will return a L<Class::MOP::Class> instance for this class.
1748 It should also be noted that L<Class::MOP> will actually bootstrap
1749 this module by installing a number of attribute meta-objects into its
1756 Stevan Little E<lt>stevan@iinteractive.comE<gt>
1758 =head1 COPYRIGHT AND LICENSE
1760 Copyright 2006-2009 by Infinity Interactive, Inc.
1762 L<http://www.iinteractive.com>
1764 This library is free software; you can redistribute it and/or modify
1765 it under the same terms as Perl itself.