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 $meta->is_anon_class;
110 return Class::MOP::Class->initialize($class)->new_object(@_)
111 if $class ne __PACKAGE__;
113 my $options = @_ == 1 ? $_[0] : {@_};
116 # inherited from Class::MOP::Package
117 'package' => $options->{package},
120 # since the following attributes will
121 # actually be loaded from the symbol
122 # table, and actually bypass the instance
123 # entirely, we can just leave these things
124 # listed here for reference, because they
125 # should not actually have a value associated
127 'namespace' => \undef,
129 # inherited from Class::MOP::Module
131 'authority' => \undef,
133 # defined in Class::MOP::Class
134 'superclasses' => \undef,
138 'attribute_metaclass' =>
139 ( $options->{'attribute_metaclass'} || 'Class::MOP::Attribute' ),
140 'method_metaclass' =>
141 ( $options->{'method_metaclass'} || 'Class::MOP::Method' ),
142 'wrapped_method_metaclass' => (
143 $options->{'wrapped_method_metaclass'}
144 || 'Class::MOP::Method::Wrapped'
146 'instance_metaclass' =>
147 ( $options->{'instance_metaclass'} || 'Class::MOP::Instance' ),
148 'immutable_trait' => (
149 $options->{'immutable_trait'}
150 || 'Class::MOP::Class::Immutable::Trait'
152 'constructor_name' => ( $options->{constructor_name} || 'new' ),
153 'constructor_class' => (
154 $options->{constructor_class} || 'Class::MOP::Method::Constructor'
156 'destructor_class' => $options->{destructor_class},
160 sub reset_package_cache_flag { (shift)->{'_package_cache_flag'} = undef }
161 sub update_package_cache_flag {
164 # we can manually update the cache number
165 # since we are actually adding the method
166 # to our cache as well. This avoids us
167 # having to regenerate the method_map.
169 $self->{'_package_cache_flag'} = Class::MOP::check_package_cache_flag($self->name);
173 sub check_metaclass_compatibility {
174 Carp::cluck('The check_metaclass_compatibility method has been made private.'
175 . " The public version is deprecated and will be removed in a future release.\n");
176 shift->_check_metaclass_compatibility(@_);
179 sub _check_metaclass_compatibility {
182 # this is always okay ...
183 return if ref($self) eq 'Class::MOP::Class' &&
184 $self->instance_metaclass eq 'Class::MOP::Instance';
186 my @class_list = $self->linearized_isa;
187 shift @class_list; # shift off $self->name
189 foreach my $superclass_name (@class_list) {
190 my $super_meta = Class::MOP::get_metaclass_by_name($superclass_name) || next;
193 # we need to deal with the possibility
194 # of class immutability here, and then
195 # get the name of the class appropriately
197 = $super_meta->is_immutable
198 ? $super_meta->get_mutable_metaclass_name()
201 ($self->isa($super_meta_type))
202 || confess "The metaclass of " . $self->name . " ("
203 . (ref($self)) . ")" . " is not compatible with the " .
204 "metaclass of its superclass, ".$superclass_name . " ("
205 . ($super_meta_type) . ")";
207 # we also need to check that instance metaclasses
208 # are compatibile in the same the class.
209 ($self->instance_metaclass->isa($super_meta->instance_metaclass))
210 || confess "The instance metaclass for " . $self->name . " (" . ($self->instance_metaclass) . ")" .
211 " is not compatible with the " .
212 "instance metaclass of its superclass, " . $superclass_name . " (" . ($super_meta->instance_metaclass) . ")";
220 # this should be sufficient, if you have a
221 # use case where it is not, write a test and
223 my $ANON_CLASS_SERIAL = 0;
226 # we need a sufficiently annoying prefix
227 # this should suffice for now, this is
228 # used in a couple of places below, so
229 # need to put it up here for now.
230 my $ANON_CLASS_PREFIX = 'Class::MOP::Class::__ANON__::SERIAL::';
234 no warnings 'uninitialized';
235 $self->name =~ /^$ANON_CLASS_PREFIX/;
238 sub create_anon_class {
239 my ($class, %options) = @_;
240 my $package_name = $ANON_CLASS_PREFIX . ++$ANON_CLASS_SERIAL;
241 return $class->create($package_name, %options);
245 # this will only get called for
246 # anon-classes, all other calls
247 # are assumed to occur during
248 # global destruction and so don't
249 # really need to be handled explicitly
253 return if in_global_destruction(); # it'll happen soon anyway and this just makes things more complicated
255 no warnings 'uninitialized';
256 my $name = $self->name;
257 return unless $name =~ /^$ANON_CLASS_PREFIX/;
258 # Moose does a weird thing where it replaces the metaclass for
259 # class when fixing metaclass incompatibility. In that case,
260 # we don't want to clean out the namespace now. We can detect
261 # that because Moose will explicitly update the singleton
262 # cache in Class::MOP.
263 my $current_meta = Class::MOP::get_metaclass_by_name($name);
264 return if $current_meta ne $self;
266 my ($serial_id) = ($name =~ /^$ANON_CLASS_PREFIX(\d+)/);
268 @{$name . '::ISA'} = ();
269 %{$name . '::'} = ();
270 delete ${$ANON_CLASS_PREFIX}{$serial_id . '::'};
272 Class::MOP::remove_metaclass_by_name($name);
277 # creating classes with MOP ...
280 my ( $class, @args ) = @_;
282 unshift @args, 'package' if @args % 2 == 1;
284 my (%options) = @args;
285 my $package_name = $options{package};
287 (ref $options{superclasses} eq 'ARRAY')
288 || confess "You must pass an ARRAY ref of superclasses"
289 if exists $options{superclasses};
291 (ref $options{attributes} eq 'ARRAY')
292 || confess "You must pass an ARRAY ref of attributes"
293 if exists $options{attributes};
295 (ref $options{methods} eq 'HASH')
296 || confess "You must pass a HASH ref of methods"
297 if exists $options{methods};
299 my (%initialize_options) = @args;
300 delete @initialize_options{qw(
308 my $meta = $class->initialize( $package_name => %initialize_options );
310 $meta->_instantiate_module( $options{version}, $options{authority} );
313 $meta->add_method('meta' => sub {
314 $class->initialize(ref($_[0]) || $_[0]);
317 $meta->superclasses(@{$options{superclasses}})
318 if exists $options{superclasses};
320 # process attributes first, so that they can
321 # install accessors, but locally defined methods
322 # can then overwrite them. It is maybe a little odd, but
323 # I think this should be the order of things.
324 if (exists $options{attributes}) {
325 foreach my $attr (@{$options{attributes}}) {
326 $meta->add_attribute($attr);
329 if (exists $options{methods}) {
330 foreach my $method_name (keys %{$options{methods}}) {
331 $meta->add_method($method_name, $options{methods}->{$method_name});
340 # all these attribute readers will be bootstrapped
341 # away in the Class::MOP bootstrap section
343 sub get_attribute_map { $_[0]->{'attributes'} }
344 sub attribute_metaclass { $_[0]->{'attribute_metaclass'} }
345 sub method_metaclass { $_[0]->{'method_metaclass'} }
346 sub wrapped_method_metaclass { $_[0]->{'wrapped_method_metaclass'} }
347 sub instance_metaclass { $_[0]->{'instance_metaclass'} }
348 sub immutable_trait { $_[0]->{'immutable_trait'} }
349 sub constructor_class { $_[0]->{'constructor_class'} }
350 sub constructor_name { $_[0]->{'constructor_name'} }
351 sub destructor_class { $_[0]->{'destructor_class'} }
353 sub _method_map { $_[0]->{'methods'} }
355 # Instance Construction & Cloning
361 # we need to protect the integrity of the
362 # Class::MOP::Class singletons here, so we
363 # delegate this to &construct_class_instance
364 # which will deal with the singletons
365 return $class->_construct_class_instance(@_)
366 if $class->name->isa('Class::MOP::Class');
367 return $class->_construct_instance(@_);
370 sub construct_instance {
371 Carp::cluck('The construct_instance method has been made private.'
372 . " The public version is deprecated and will be removed in a future release.\n");
373 shift->_construct_instance(@_);
376 sub _construct_instance {
378 my $params = @_ == 1 ? $_[0] : {@_};
379 my $meta_instance = $class->get_meta_instance();
381 # the code below is almost certainly incorrect
382 # but this is foreign inheritance, so we might
383 # have to kludge it in the end.
384 my $instance = $params->{__INSTANCE__} || $meta_instance->create_instance();
385 foreach my $attr ($class->get_all_attributes()) {
386 $attr->initialize_instance_slot($meta_instance, $instance, $params);
389 # this will only work for a HASH instance type
390 if ($class->is_anon_class) {
391 (Scalar::Util::reftype($instance) eq 'HASH')
392 || confess "Currently only HASH based instances are supported with instance of anon-classes";
394 # At some point we should make this official
395 # as a reserved slot name, but right now I am
396 # going to keep it here.
397 # my $RESERVED_MOP_SLOT = '__MOP__';
398 $instance->{'__MOP__'} = $class;
404 sub get_meta_instance {
406 $self->{'_meta_instance'} ||= $self->_create_meta_instance();
409 sub create_meta_instance {
410 Carp::cluck('The create_meta_instance method has been made private.'
411 . " The public version is deprecated and will be removed in a future release.\n");
412 shift->_create_meta_instance(@_);
415 sub _create_meta_instance {
418 my $instance = $self->instance_metaclass->new(
419 associated_metaclass => $self,
420 attributes => [ $self->get_all_attributes() ],
423 $self->add_meta_instance_dependencies()
424 if $instance->is_dependent_on_superclasses();
431 my $instance = shift;
432 (blessed($instance) && $instance->isa($class->name))
433 || confess "You must pass an instance of the metaclass (" . (ref $class ? $class->name : $class) . "), not ($instance)";
436 # we need to protect the integrity of the
437 # Class::MOP::Class singletons here, they
438 # should not be cloned.
439 return $instance if $instance->isa('Class::MOP::Class');
440 $class->_clone_instance($instance, @_);
444 Carp::cluck('The clone_instance method has been made private.'
445 . " The public version is deprecated and will be removed in a future release.\n");
446 shift->_clone_instance(@_);
449 sub _clone_instance {
450 my ($class, $instance, %params) = @_;
452 || confess "You can only clone instances, ($instance) is not a blessed instance";
453 my $meta_instance = $class->get_meta_instance();
454 my $clone = $meta_instance->clone_instance($instance);
455 foreach my $attr ($class->get_all_attributes()) {
456 if ( defined( my $init_arg = $attr->init_arg ) ) {
457 if (exists $params{$init_arg}) {
458 $attr->set_value($clone, $params{$init_arg});
465 sub rebless_instance {
466 my ($self, $instance, %params) = @_;
468 my $old_metaclass = Class::MOP::class_of($instance);
470 my $old_class = $old_metaclass ? $old_metaclass->name : blessed($instance);
471 $self->name->isa($old_class)
472 || confess "You may rebless only into a subclass of ($old_class), of which (". $self->name .") isn't.";
474 $old_metaclass->rebless_instance_away($instance, $self, %params)
477 my $meta_instance = $self->get_meta_instance();
480 # we use $_[1] here because of t/306_rebless_overload.t regressions on 5.8.8
481 $meta_instance->rebless_instance_structure($_[1], $self);
483 foreach my $attr ( $self->get_all_attributes ) {
484 if ( $attr->has_value($instance) ) {
485 if ( defined( my $init_arg = $attr->init_arg ) ) {
486 $params{$init_arg} = $attr->get_value($instance)
487 unless exists $params{$init_arg};
490 $attr->set_value($instance, $attr->get_value($instance));
495 foreach my $attr ($self->get_all_attributes) {
496 $attr->initialize_instance_slot($meta_instance, $instance, \%params);
502 sub rebless_instance_away {
503 # this intentionally does nothing, it is just a hook
510 my $var_spec = { sigil => '@', type => 'ARRAY', name => 'ISA' };
513 @{$self->get_package_symbol($var_spec)} = @supers;
516 # on 5.8 and below, we need to call
517 # a method to get Perl to detect
518 # a cycle in the class hierarchy
519 my $class = $self->name;
523 # we need to check the metaclass
524 # compatibility here so that we can
525 # be sure that the superclass is
526 # not potentially creating an issues
527 # we don't know about
529 $self->_check_metaclass_compatibility();
530 $self->_superclasses_updated();
532 @{$self->get_package_symbol($var_spec)};
535 sub _superclasses_updated {
537 $self->update_meta_instance_dependencies();
542 my $super_class = $self->name;
544 return @{ $super_class->mro::get_isarev() };
547 sub direct_subclasses {
549 my $super_class = $self->name;
554 } Class::MOP::Class->initialize($_)->superclasses
559 return @{ mro::get_linear_isa( (shift)->name ) };
562 sub class_precedence_list {
564 my $name = $self->name;
566 unless (Class::MOP::IS_RUNNING_ON_5_10()) {
568 # We need to check for circular inheritance here
569 # if we are are not on 5.10, cause 5.8 detects it
570 # late. This will do nothing if all is well, and
571 # blow up otherwise. Yes, it's an ugly hack, better
572 # suggestions are welcome.
574 ($name || return)->isa('This is a test for circular inheritance')
577 # if our mro is c3, we can
578 # just grab the linear_isa
579 if (mro::get_mro($name) eq 'c3') {
580 return @{ mro::get_linear_isa($name) }
584 # we can't grab the linear_isa for dfs
585 # since it has all the duplicates
590 $self->initialize($_)->class_precedence_list()
591 } $self->superclasses()
598 sub wrap_method_body {
599 my ( $self, %args ) = @_;
601 ('CODE' eq ref $args{body})
602 || confess "Your code block must be a CODE reference";
604 $self->method_metaclass->wrap(
605 package_name => $self->name,
611 my ($self, $method_name, $method) = @_;
612 (defined $method_name && $method_name)
613 || confess "You must define a method name";
616 if (blessed($method)) {
617 $body = $method->body;
618 if ($method->package_name ne $self->name) {
619 $method = $method->clone(
620 package_name => $self->name,
622 ) if $method->can('clone');
625 $method->attach_to_class($self);
626 $self->_method_map->{$method_name} = $method;
629 # If a raw code reference is supplied, its method object is not created.
630 # The method object won't be created until required.
635 my ( $current_package, $current_name ) = Class::MOP::get_code_info($body);
637 if ( !defined $current_name || $current_name eq '__ANON__' ) {
638 my $full_method_name = ($self->name . '::' . $method_name);
639 subname($full_method_name => $body);
642 $self->add_package_symbol(
643 { sigil => '&', type => 'CODE', name => $method_name },
649 my $fetch_and_prepare_method = sub {
650 my ($self, $method_name) = @_;
651 my $wrapped_metaclass = $self->wrapped_method_metaclass;
653 my $method = $self->get_method($method_name);
654 # if we dont have local ...
656 # try to find the next method
657 $method = $self->find_next_method_by_name($method_name);
658 # die if it does not exist
660 || confess "The method '$method_name' was not found in the inheritance hierarchy for " . $self->name;
661 # and now make sure to wrap it
662 # even if it is already wrapped
663 # because we need a new sub ref
664 $method = $wrapped_metaclass->wrap($method);
667 # now make sure we wrap it properly
668 $method = $wrapped_metaclass->wrap($method)
669 unless $method->isa($wrapped_metaclass);
671 $self->add_method($method_name => $method);
675 sub add_before_method_modifier {
676 my ($self, $method_name, $method_modifier) = @_;
677 (defined $method_name && $method_name)
678 || confess "You must pass in a method name";
679 my $method = $fetch_and_prepare_method->($self, $method_name);
680 $method->add_before_modifier(
681 subname(':before' => $method_modifier)
685 sub add_after_method_modifier {
686 my ($self, $method_name, $method_modifier) = @_;
687 (defined $method_name && $method_name)
688 || confess "You must pass in a method name";
689 my $method = $fetch_and_prepare_method->($self, $method_name);
690 $method->add_after_modifier(
691 subname(':after' => $method_modifier)
695 sub add_around_method_modifier {
696 my ($self, $method_name, $method_modifier) = @_;
697 (defined $method_name && $method_name)
698 || confess "You must pass in a method name";
699 my $method = $fetch_and_prepare_method->($self, $method_name);
700 $method->add_around_modifier(
701 subname(':around' => $method_modifier)
706 # the methods above used to be named like this:
707 # ${pkg}::${method}:(before|after|around)
708 # but this proved problematic when using one modifier
709 # to wrap multiple methods (something which is likely
710 # to happen pretty regularly IMO). So instead of naming
711 # it like this, I have chosen to just name them purely
712 # with their modifier names, like so:
713 # :(before|after|around)
714 # The fact is that in a stack trace, it will be fairly
715 # evident from the context what method they are attached
716 # to, and so don't need the fully qualified name.
720 Carp::cluck("The alias_method method is deprecated. Use add_method instead.\n");
722 shift->add_method(@_);
726 my($self, $code) = @_;
727 my($code_package, $code_name) = Class::MOP::get_code_info($code);
729 && $code_package eq $self->name
730 || ($code_package eq 'constant' && $code_name eq '__ANON__');
734 my ($self, $method_name) = @_;
735 (defined $method_name && $method_name)
736 || confess "You must define a method name";
738 return defined($self->get_method($method_name));
742 my ($self, $method_name) = @_;
743 (defined $method_name && $method_name)
744 || confess "You must define a method name";
746 my $method_map = $self->_method_map;
747 my $method_object = $method_map->{$method_name};
748 my $code = $self->get_package_symbol({
749 name => $method_name,
754 if (!($method_object && $method_object->body == ($code || 0))){
755 if ($code && $self->_code_is_mine($code)) {
756 $method_object = $method_map->{$method_name} = $self->wrap_method_body(
758 name => $method_name,
759 associated_metaclass => $self,
763 delete $method_map->{$method_name};
768 return $method_object;
772 my ($self, $method_name) = @_;
773 (defined $method_name && $method_name)
774 || confess "You must define a method name";
776 my $removed_method = delete $self->get_method_map->{$method_name};
778 $self->remove_package_symbol(
779 { sigil => '&', type => 'CODE', name => $method_name }
782 $removed_method->detach_from_class if $removed_method;
784 $self->update_package_cache_flag; # still valid, since we just removed the method from the map
786 return $removed_method;
789 sub get_method_list {
791 return grep { $self->has_method($_) } keys %{ $self->namespace };
794 sub find_method_by_name {
795 my ($self, $method_name) = @_;
796 (defined $method_name && $method_name)
797 || confess "You must define a method name to find";
798 foreach my $class ($self->linearized_isa) {
799 # fetch the meta-class ...
800 my $meta = $self->initialize($class);
801 return $meta->get_method($method_name)
802 if $meta->has_method($method_name);
807 sub get_all_methods {
809 my %methods = map { %{ $self->initialize($_)->get_method_map } } reverse $self->linearized_isa;
810 return values %methods;
813 sub compute_all_applicable_methods {
814 Carp::cluck('The compute_all_applicable_methods method is deprecated.'
815 . " Use get_all_methods instead.\n");
820 class => $_->package_name,
821 code => $_, # sigh, overloading
823 } shift->get_all_methods(@_);
826 sub get_all_method_names {
829 return grep { !$uniq{$_}++ } map { $self->initialize($_)->get_method_list } $self->linearized_isa;
832 sub find_all_methods_by_name {
833 my ($self, $method_name) = @_;
834 (defined $method_name && $method_name)
835 || confess "You must define a method name to find";
837 foreach my $class ($self->linearized_isa) {
838 # fetch the meta-class ...
839 my $meta = $self->initialize($class);
841 name => $method_name,
843 code => $meta->get_method($method_name)
844 } if $meta->has_method($method_name);
849 sub find_next_method_by_name {
850 my ($self, $method_name) = @_;
851 (defined $method_name && $method_name)
852 || confess "You must define a method name to find";
853 my @cpl = $self->linearized_isa;
854 shift @cpl; # discard ourselves
855 foreach my $class (@cpl) {
856 # fetch the meta-class ...
857 my $meta = $self->initialize($class);
858 return $meta->get_method($method_name)
859 if $meta->has_method($method_name);
868 # either we have an attribute object already
869 # or we need to create one from the args provided
870 my $attribute = blessed($_[0]) ? $_[0] : $self->attribute_metaclass->new(@_);
871 # make sure it is derived from the correct type though
872 ($attribute->isa('Class::MOP::Attribute'))
873 || confess "Your attribute must be an instance of Class::MOP::Attribute (or a subclass)";
875 # first we attach our new attribute
876 # because it might need certain information
877 # about the class which it is attached to
878 $attribute->attach_to_class($self);
880 my $attr_name = $attribute->name;
882 # then we remove attributes of a conflicting
883 # name here so that we can properly detach
884 # the old attr object, and remove any
885 # accessors it would have generated
886 if ( $self->has_attribute($attr_name) ) {
887 $self->remove_attribute($attr_name);
889 $self->invalidate_meta_instances();
892 # get our count of previously inserted attributes and
893 # increment by one so this attribute knows its order
894 my $order = (scalar keys %{$self->get_attribute_map});
895 $attribute->_set_insertion_order($order);
897 # then onto installing the new accessors
898 $self->get_attribute_map->{$attr_name} = $attribute;
900 # invalidate package flag here
904 eval { $attribute->install_accessors() };
908 $self->remove_attribute($attr_name);
915 sub update_meta_instance_dependencies {
918 if ( $self->{meta_instance_dependencies} ) {
919 return $self->add_meta_instance_dependencies;
923 sub add_meta_instance_dependencies {
926 $self->remove_meta_instance_dependencies;
928 my @attrs = $self->get_all_attributes();
931 my @classes = grep { not $seen{$_->name}++ } map { $_->associated_class } @attrs;
933 foreach my $class ( @classes ) {
934 $class->add_dependent_meta_instance($self);
937 $self->{meta_instance_dependencies} = \@classes;
940 sub remove_meta_instance_dependencies {
943 if ( my $classes = delete $self->{meta_instance_dependencies} ) {
944 foreach my $class ( @$classes ) {
945 $class->remove_dependent_meta_instance($self);
955 sub add_dependent_meta_instance {
956 my ( $self, $metaclass ) = @_;
957 push @{ $self->{dependent_meta_instances} }, $metaclass;
960 sub remove_dependent_meta_instance {
961 my ( $self, $metaclass ) = @_;
962 my $name = $metaclass->name;
963 @$_ = grep { $_->name ne $name } @$_ for $self->{dependent_meta_instances};
966 sub invalidate_meta_instances {
968 $_->invalidate_meta_instance() for $self, @{ $self->{dependent_meta_instances} };
971 sub invalidate_meta_instance {
973 undef $self->{_meta_instance};
977 my ($self, $attribute_name) = @_;
978 (defined $attribute_name && $attribute_name)
979 || confess "You must define an attribute name";
980 exists $self->get_attribute_map->{$attribute_name};
984 my ($self, $attribute_name) = @_;
985 (defined $attribute_name && $attribute_name)
986 || confess "You must define an attribute name";
987 return $self->get_attribute_map->{$attribute_name}
989 # this will return undef anyway, so no need ...
990 # if $self->has_attribute($attribute_name);
994 sub remove_attribute {
995 my ($self, $attribute_name) = @_;
996 (defined $attribute_name && $attribute_name)
997 || confess "You must define an attribute name";
998 my $removed_attribute = $self->get_attribute_map->{$attribute_name};
999 return unless defined $removed_attribute;
1000 delete $self->get_attribute_map->{$attribute_name};
1001 $self->invalidate_meta_instances();
1002 $removed_attribute->remove_accessors();
1003 $removed_attribute->detach_from_class();
1004 return $removed_attribute;
1007 sub get_attribute_list {
1009 keys %{$self->get_attribute_map};
1012 sub get_all_attributes {
1014 my %attrs = map { %{ $self->initialize($_)->get_attribute_map } } reverse $self->linearized_isa;
1015 return values %attrs;
1018 sub compute_all_applicable_attributes {
1019 Carp::cluck('The compute_all_applicable_attributes method has been deprecated.'
1020 . " Use get_all_attributes instead.\n");
1022 shift->get_all_attributes(@_);
1025 sub find_attribute_by_name {
1026 my ($self, $attr_name) = @_;
1027 foreach my $class ($self->linearized_isa) {
1028 # fetch the meta-class ...
1029 my $meta = $self->initialize($class);
1030 return $meta->get_attribute($attr_name)
1031 if $meta->has_attribute($attr_name);
1036 # check if we can reinitialize
1040 # if any local attr is defined
1041 return if $self->get_attribute_list;
1043 # or any non-declared methods
1044 if ( my @methods = values %{ $self->get_method_map } ) {
1045 my $metaclass = $self->method_metaclass;
1046 foreach my $method ( @methods ) {
1047 return if $method->isa("Class::MOP::Method::Generated");
1048 # FIXME do we need to enforce this too? return unless $method->isa($metaclass);
1057 sub is_mutable { 1 }
1058 sub is_immutable { 0 }
1060 sub _immutable_options {
1061 my ( $self, @args ) = @_;
1064 inline_accessors => 1,
1065 inline_constructor => 1,
1066 inline_destructor => 0,
1068 immutable_trait => $self->immutable_trait,
1069 constructor_name => $self->constructor_name,
1070 constructor_class => $self->constructor_class,
1071 destructor_class => $self->destructor_class,
1076 sub make_immutable {
1077 my ( $self, @args ) = @_;
1079 if ( $self->is_mutable ) {
1080 $self->_initialize_immutable( $self->_immutable_options(@args) );
1081 $self->_rebless_as_immutable(@args);
1092 if ( $self->is_immutable ) {
1093 my @args = $self->immutable_options;
1094 $self->_rebless_as_mutable();
1095 $self->_remove_inlined_code(@args);
1096 delete $self->{__immutable};
1104 sub _rebless_as_immutable {
1105 my ( $self, @args ) = @_;
1107 $self->{__immutable}{original_class} = ref $self;
1109 bless $self => $self->_immutable_metaclass(@args);
1112 sub _immutable_metaclass {
1113 my ( $self, %args ) = @_;
1115 if ( my $class = $args{immutable_metaclass} ) {
1119 my $trait = $args{immutable_trait} = $self->immutable_trait
1120 || confess "no immutable trait specified for $self";
1122 my $meta_attr = $self->meta->find_attribute_by_name("immutable_trait");
1126 if ( $meta_attr and $trait eq $meta_attr->default ) {
1127 # if the trait is the same as the default we try and pick a
1128 # predictable name for the immutable metaclass
1129 $class_name = 'Class::MOP::Class::Immutable::' . ref($self);
1132 $class_name = join '::', 'Class::MOP::Class::Immutable::CustomTrait',
1133 $trait, 'ForMetaClass', ref($self);
1137 if Class::MOP::is_class_loaded($class_name);
1139 # If the metaclass is a subclass of CMOP::Class which has had
1140 # metaclass roles applied (via Moose), then we want to make sure
1141 # that we preserve that anonymous class (see Fey::ORM for an
1142 # example of where this matters).
1144 = $self->meta->is_immutable
1145 ? $self->meta->get_mutable_metaclass_name
1148 my $meta = $meta_name->create(
1150 superclasses => [ ref $self ],
1153 Class::MOP::load_class($trait);
1154 for my $meth ( Class::MOP::Class->initialize($trait)->get_all_methods ) {
1155 next if $meta->has_method( $meth->name );
1157 if ( $meta->find_method_by_name( $meth->name ) ) {
1158 $meta->add_around_method_modifier( $meth->name, $meth->body );
1161 $meta->add_method( $meth->name, $meth->clone );
1165 $meta->make_immutable( inline_constructor => 0 );
1170 sub _remove_inlined_code {
1173 $self->remove_method( $_->name ) for $self->_inlined_methods;
1175 delete $self->{__immutable}{inlined_methods};
1178 sub _inlined_methods { @{ $_[0]{__immutable}{inlined_methods} || [] } }
1180 sub _add_inlined_method {
1181 my ( $self, $method ) = @_;
1183 push @{ $self->{__immutable}{inlined_methods} ||= [] }, $method;
1186 sub _initialize_immutable {
1187 my ( $self, %args ) = @_;
1189 $self->{__immutable}{options} = \%args;
1190 $self->_install_inlined_code(%args);
1193 sub _install_inlined_code {
1194 my ( $self, %args ) = @_;
1197 $self->_inline_accessors(%args) if $args{inline_accessors};
1198 $self->_inline_constructor(%args) if $args{inline_constructor};
1199 $self->_inline_destructor(%args) if $args{inline_destructor};
1202 sub _rebless_as_mutable {
1205 bless $self, $self->get_mutable_metaclass_name;
1210 sub _inline_accessors {
1213 foreach my $attr_name ( $self->get_attribute_list ) {
1214 $self->get_attribute($attr_name)->install_accessors(1);
1218 sub _inline_constructor {
1219 my ( $self, %args ) = @_;
1221 my $name = $args{constructor_name};
1223 if ( $self->has_method($name) && !$args{replace_constructor} ) {
1224 my $class = $self->name;
1225 warn "Not inlining a constructor for $class since it defines"
1226 . " its own constructor.\n"
1227 . "If you are certain you don't need to inline your"
1228 . " constructor, specify inline_constructor => 0 in your"
1229 . " call to $class->meta->make_immutable\n";
1233 my $constructor_class = $args{constructor_class};
1235 Class::MOP::load_class($constructor_class);
1237 my $constructor = $constructor_class->new(
1241 package_name => $self->name,
1245 if ( $args{replace_constructor} or $constructor->can_be_inlined ) {
1246 $self->add_method( $name => $constructor );
1247 $self->_add_inlined_method($constructor);
1251 sub _inline_destructor {
1252 my ( $self, %args ) = @_;
1254 ( exists $args{destructor_class} && defined $args{destructor_class} )
1255 || confess "The 'inline_destructor' option is present, but "
1256 . "no destructor class was specified";
1258 if ( $self->has_method('DESTROY') && ! $args{replace_destructor} ) {
1259 my $class = $self->name;
1260 warn "Not inlining a destructor for $class since it defines"
1261 . " its own destructor.\n";
1265 my $destructor_class = $args{destructor_class};
1267 Class::MOP::load_class($destructor_class);
1269 return unless $destructor_class->is_needed($self);
1271 my $destructor = $destructor_class->new(
1274 package_name => $self->name,
1278 if ( $args{replace_destructor} or $destructor->can_be_inlined ) {
1279 $self->add_method( 'DESTROY' => $destructor );
1280 $self->_add_inlined_method($destructor);
1292 Class::MOP::Class - Class Meta Object
1296 # assuming that class Foo
1297 # has been defined, you can
1299 # use this for introspection ...
1301 # add a method to Foo ...
1302 Foo->meta->add_method( 'bar' => sub {...} )
1304 # get a list of all the classes searched
1305 # the method dispatcher in the correct order
1306 Foo->meta->class_precedence_list()
1308 # remove a method from Foo
1309 Foo->meta->remove_method('bar');
1311 # or use this to actually create classes ...
1313 Class::MOP::Class->create(
1316 superclasses => ['Foo'],
1318 Class::MOP::Attribute->new('$bar'),
1319 Class::MOP::Attribute->new('$baz'),
1322 calculate_bar => sub {...},
1323 construct_baz => sub {...}
1330 The Class Protocol is the largest and most complex part of the
1331 Class::MOP meta-object protocol. It controls the introspection and
1332 manipulation of Perl 5 classes, and it can create them as well. The
1333 best way to understand what this module can do, is to read the
1334 documentation for each of its methods.
1338 C<Class::MOP::Class> is a subclass of L<Class::MOP::Module>.
1342 =head2 Class construction
1344 These methods all create new C<Class::MOP::Class> objects. These
1345 objects can represent existing classes, or they can be used to create
1346 new classes from scratch.
1348 The metaclass object for a given class is a singleton. If you attempt
1349 to create a metaclass for the same class twice, you will just get the
1354 =item B<< Class::MOP::Class->create($package_name, %options) >>
1356 This method creates a new C<Class::MOP::Class> object with the given
1357 package name. It accepts a number of options.
1363 An optional version number for the newly created package.
1367 An optional authority for the newly created package.
1369 =item * superclasses
1371 An optional array reference of superclass names.
1375 An optional hash reference of methods for the class. The keys of the
1376 hash reference are method names, and values are subroutine references.
1380 An optional array reference of L<Class::MOP::Attribute> objects.
1384 =item B<< Class::MOP::Class->create_anon_class(%options) >>
1386 This method works just like C<< Class::MOP::Class->create >> but it
1387 creates an "anonymous" class. In fact, the class does have a name, but
1388 that name is a unique name generated internally by this module.
1390 It accepts the same C<superclasses>, C<methods>, and C<attributes>
1391 parameters that C<create> accepts.
1393 Anonymous classes are destroyed once the metaclass they are attached
1394 to goes out of scope, and will be removed from Perl's internal symbol
1397 All instances of an anonymous class keep a special reference to the
1398 metaclass object, which prevents the metaclass from going out of scope
1399 while any instances exist.
1401 This only works if the instance if based on a hash reference, however.
1403 =item B<< Class::MOP::Class->initialize($package_name, %options) >>
1405 This method will initialize a C<Class::MOP::Class> object for the
1406 named package. Unlike C<create>, this method I<will not> create a new
1409 The purpose of this method is to retrieve a C<Class::MOP::Class>
1410 object for introspecting an existing class.
1412 If an existing C<Class::MOP::Class> object exists for the named
1413 package, it will be returned, and any options provided will be
1416 If the object does not yet exist, it will be created.
1418 The valid options that can be passed to this method are
1419 C<attribute_metaclass>, C<method_metaclass>,
1420 C<wrapped_method_metaclass>, and C<instance_metaclass>. These are all
1421 optional, and default to the appropriate class in the C<Class::MOP>
1426 =head2 Object instance construction and cloning
1428 These methods are all related to creating and/or cloning object
1433 =item B<< $metaclass->clone_object($instance, %params) >>
1435 This method clones an existing object instance. Any parameters you
1436 provide are will override existing attribute values in the object.
1438 This is a convenience method for cloning an object instance, then
1439 blessing it into the appropriate package.
1441 You could implement a clone method in your class, using this method:
1444 my ($self, %params) = @_;
1445 $self->meta->clone_object($self, %params);
1448 =item B<< $metaclass->rebless_instance($instance, %params) >>
1450 This method changes the class of C<$instance> to the metaclass's class.
1452 You can only rebless an instance into a subclass of its current
1453 class. If you pass any additional parameters, these will be treated
1454 like constructor parameters and used to initialize the object's
1455 attributes. Any existing attributes that are already set will be
1458 Before reblessing the instance, this method will call
1459 C<rebless_instance_away> on the instance's current metaclass. This method
1460 will be passed the instance, the new metaclass, and any parameters
1461 specified to C<rebless_instance>. By default, C<rebless_instance_away>
1462 does nothing; it is merely a hook.
1464 =item B<< $metaclass->new_object(%params) >>
1466 This method is used to create a new object of the metaclass's
1467 class. Any parameters you provide are used to initialize the
1468 instance's attributes. A special C<__INSTANCE__> key can be passed to
1469 provide an already generated instance, rather than having Class::MOP
1470 generate it for you. This is mostly useful for using Class::MOP with
1471 foreign classes, which generally generate instances using their own
1474 =item B<< $metaclass->instance_metaclass >>
1476 Returns the class name of the instance metaclass, see
1477 L<Class::MOP::Instance> for more information on the instance
1480 =item B<< $metaclass->get_meta_instance >>
1482 Returns an instance of the C<instance_metaclass> to be used in the
1483 construction of a new instance of the class.
1487 =head2 Informational predicates
1489 These are a few predicate methods for asking information about the
1494 =item B<< $metaclass->is_anon_class >>
1496 This returns true if the class was created by calling C<<
1497 Class::MOP::Class->create_anon_class >>.
1499 =item B<< $metaclass->is_mutable >>
1501 This returns true if the class is still mutable.
1503 =item B<< $metaclass->is_immutable >>
1505 This returns true if the class has been made immutable.
1507 =item B<< $metaclass->is_pristine >>
1509 A class is I<not> pristine if it has non-inherited attributes or if it
1510 has any generated methods.
1514 =head2 Inheritance Relationships
1518 =item B<< $metaclass->superclasses(@superclasses) >>
1520 This is a read-write accessor which represents the superclass
1521 relationships of the metaclass's class.
1523 This is basically sugar around getting and setting C<@ISA>.
1525 =item B<< $metaclass->class_precedence_list >>
1527 This returns a list of all of the class's ancestor classes. The
1528 classes are returned in method dispatch order.
1530 =item B<< $metaclass->linearized_isa >>
1532 This returns a list based on C<class_precedence_list> but with all
1535 =item B<< $metaclass->subclasses >>
1537 This returns a list of all subclasses for this class, even indirect
1540 =item B<< $metaclass->direct_subclasses >>
1542 This returns a list of immediate subclasses for this class, which does not
1543 include indirect subclasses.
1547 =head2 Method introspection and creation
1549 These methods allow you to introspect a class's methods, as well as
1550 add, remove, or change methods.
1552 Determining what is truly a method in a Perl 5 class requires some
1553 heuristics (aka guessing).
1555 Methods defined outside the package with a fully qualified name (C<sub
1556 Package::name { ... }>) will be included. Similarly, methods named
1557 with a fully qualified name using L<Sub::Name> are also included.
1559 However, we attempt to ignore imported functions.
1561 Ultimately, we are using heuristics to determine what truly is a
1562 method in a class, and these heuristics may get the wrong answer in
1563 some edge cases. However, for most "normal" cases the heuristics work
1568 =item B<< $metaclass->get_method($method_name) >>
1570 This will return a L<Class::MOP::Method> for the specified
1571 C<$method_name>. If the class does not have the specified method, it
1574 =item B<< $metaclass->has_method($method_name) >>
1576 Returns a boolean indicating whether or not the class defines the
1577 named method. It does not include methods inherited from parent
1580 =item B<< $metaclass->get_method_map >>
1582 Returns a hash reference representing the methods defined in this
1583 class. The keys are method names and the values are
1584 L<Class::MOP::Method> objects.
1586 =item B<< $metaclass->get_method_list >>
1588 This will return a list of method I<names> for all methods defined in
1591 =item B<< $metaclass->get_all_methods >>
1593 This will traverse the inheritance hierarchy and return a list of all
1594 the L<Class::MOP::Method> objects for this class and its parents.
1596 =item B<< $metaclass->find_method_by_name($method_name) >>
1598 This will return a L<Class::MOP::Method> for the specified
1599 C<$method_name>. If the class does not have the specified method, it
1602 Unlike C<get_method>, this method I<will> look for the named method in
1605 =item B<< $metaclass->get_all_method_names >>
1607 This will return a list of method I<names> for all of this class's
1608 methods, including inherited methods.
1610 =item B<< $metaclass->find_all_methods_by_name($method_name) >>
1612 This method looks for the named method in the class and all of its
1613 parents. It returns every matching method it finds in the inheritance
1614 tree, so it returns a list of methods.
1616 Each method is returned as a hash reference with three keys. The keys
1617 are C<name>, C<class>, and C<code>. The C<code> key has a
1618 L<Class::MOP::Method> object as its value.
1620 The list of methods is distinct.
1622 =item B<< $metaclass->find_next_method_by_name($method_name) >>
1624 This method returns the first method in any superclass matching the
1625 given name. It is effectively the method that C<SUPER::$method_name>
1628 =item B<< $metaclass->add_method($method_name, $method) >>
1630 This method takes a method name and a subroutine reference, and adds
1631 the method to the class.
1633 The subroutine reference can be a L<Class::MOP::Method>, and you are
1634 strongly encouraged to pass a meta method object instead of a code
1635 reference. If you do so, that object gets stored as part of the
1636 class's method map directly. If not, the meta information will have to
1637 be recreated later, and may be incorrect.
1639 If you provide a method object, this method will clone that object if
1640 the object's package name does not match the class name. This lets us
1641 track the original source of any methods added from other classes
1642 (notably Moose roles).
1644 =item B<< $metaclass->remove_method($method_name) >>
1646 Remove the named method from the class. This method returns the
1647 L<Class::MOP::Method> object for the method.
1649 =item B<< $metaclass->method_metaclass >>
1651 Returns the class name of the method metaclass, see
1652 L<Class::MOP::Method> for more information on the method metaclass.
1654 =item B<< $metaclass->wrapped_method_metaclass >>
1656 Returns the class name of the wrapped method metaclass, see
1657 L<Class::MOP::Method::Wrapped> for more information on the wrapped
1662 =head2 Attribute introspection and creation
1664 Because Perl 5 does not have a core concept of attributes in classes,
1665 we can only return information about attributes which have been added
1666 via this class's methods. We cannot discover information about
1667 attributes which are defined in terms of "regular" Perl 5 methods.
1671 =item B<< $metaclass->get_attribute($attribute_name) >>
1673 This will return a L<Class::MOP::Attribute> for the specified
1674 C<$attribute_name>. If the class does not have the specified
1675 attribute, it returns C<undef>.
1677 NOTE that get_attribute does not search superclasses, for that you
1678 need to use C<find_attribute_by_name>.
1680 =item B<< $metaclass->has_attribute($attribute_name) >>
1682 Returns a boolean indicating whether or not the class defines the
1683 named attribute. It does not include attributes inherited from parent
1686 =item B<< $metaclass->get_attribute_map >>
1688 Returns a hash reference representing the attributes defined in this
1689 class. The keys are attribute names and the values are
1690 L<Class::MOP::Attribute> objects.
1692 =item B<< $metaclass->get_attribute_list >>
1694 This will return a list of attributes I<names> for all attributes
1695 defined in this class.
1697 =item B<< $metaclass->get_all_attributes >>
1699 This will traverse the inheritance hierarchy and return a list of all
1700 the L<Class::MOP::Attribute> objects for this class and its parents.
1702 =item B<< $metaclass->find_attribute_by_name($attribute_name) >>
1704 This will return a L<Class::MOP::Attribute> for the specified
1705 C<$attribute_name>. If the class does not have the specified
1706 attribute, it returns C<undef>
1708 Unlike C<get_attribute>, this attribute I<will> look for the named
1709 attribute in superclasses.
1711 =item B<< $metaclass->add_attribute(...) >>
1713 This method accepts either an existing L<Class::MOP::Attribute>
1714 object, or parameters suitable for passing to that class's C<new>
1717 The attribute provided will be added to the class.
1719 Any accessor methods defined by the attribute will be added to the
1720 class when the attribute is added.
1722 If an attribute of the same name already exists, the old attribute
1723 will be removed first.
1725 =item B<< $metaclass->remove_attribute($attribute_name) >>
1727 This will remove the named attribute from the class, and
1728 L<Class::MOP::Attribute> object.
1730 Removing an attribute also removes any accessor methods defined by the
1733 However, note that removing an attribute will only affect I<future>
1734 object instances created for this class, not existing instances.
1736 =item B<< $metaclass->attribute_metaclass >>
1738 Returns the class name of the attribute metaclass for this class. By
1739 default, this is L<Class::MOP::Attribute>. for more information on
1743 =head2 Class Immutability
1745 Making a class immutable "freezes" the class definition. You can no
1746 longer call methods which alter the class, such as adding or removing
1747 methods or attributes.
1749 Making a class immutable lets us optimize the class by inlining some
1750 methods, and also allows us to optimize some methods on the metaclass
1753 After immutabilization, the metaclass object will cache most
1754 informational methods such as C<get_method_map> and
1755 C<get_all_attributes>. Methods which would alter the class, such as
1756 C<add_attribute>, C<add_method>, and so on will throw an error on an
1757 immutable metaclass object.
1759 The immutabilization system in L<Moose> takes much greater advantage
1760 of the inlining features than Class::MOP itself does.
1764 =item B<< $metaclass->make_immutable(%options) >>
1766 This method will create an immutable transformer and uses it to make
1767 the class and its metaclass object immutable.
1769 This method accepts the following options:
1773 =item * inline_accessors
1775 =item * inline_constructor
1777 =item * inline_destructor
1779 These are all booleans indicating whether the specified method(s)
1782 By default, accessors and the constructor are inlined, but not the
1785 =item * immutable_trait
1787 The name of a class which will be used as a parent class for the
1788 metaclass object being made immutable. This "trait" implements the
1789 post-immutability functionality of the metaclass (but not the
1790 transformation itself).
1792 This defaults to L<Class::MOP::Class::Immutable::Trait>.
1794 =item * constructor_name
1796 This is the constructor method name. This defaults to "new".
1798 =item * constructor_class
1800 The name of the method metaclass for constructors. It will be used to
1801 generate the inlined constructor. This defaults to
1802 "Class::MOP::Method::Constructor".
1804 =item * replace_constructor
1806 This is a boolean indicating whether an existing constructor should be
1807 replaced when inlining a constructor. This defaults to false.
1809 =item * destructor_class
1811 The name of the method metaclass for destructors. It will be used to
1812 generate the inlined destructor. This defaults to
1813 "Class::MOP::Method::Denstructor".
1815 =item * replace_destructor
1817 This is a boolean indicating whether an existing destructor should be
1818 replaced when inlining a destructor. This defaults to false.
1822 =item B<< $metaclass->make_mutable >>
1824 Calling this method reverse the immutabilization transformation.
1828 =head2 Method Modifiers
1830 Method modifiers are hooks which allow a method to be wrapped with
1831 I<before>, I<after> and I<around> method modifiers. Every time a
1832 method is called, it's modifiers are also called.
1834 A class can modify its own methods, as well as methods defined in
1837 =head3 How method modifiers work?
1839 Method modifiers work by wrapping the original method and then
1840 replacing it in the class's symbol table. The wrappers will handle
1841 calling all the modifiers in the appropriate order and preserving the
1842 calling context for the original method.
1844 The return values of C<before> and C<after> modifiers are
1845 ignored. This is because their purpose is B<not> to filter the input
1846 and output of the primary method (this is done with an I<around>
1849 This may seem like an odd restriction to some, but doing this allows
1850 for simple code to be added at the beginning or end of a method call
1851 without altering the function of the wrapped method or placing any
1852 extra responsibility on the code of the modifier.
1854 Of course if you have more complex needs, you can use the C<around>
1855 modifier which allows you to change both the parameters passed to the
1856 wrapped method, as well as its return value.
1858 Before and around modifiers are called in last-defined-first-called
1859 order, while after modifiers are called in first-defined-first-called
1860 order. So the call tree might looks something like this:
1872 =head3 What is the performance impact?
1874 Of course there is a performance cost associated with method
1875 modifiers, but we have made every effort to make that cost directly
1876 proportional to the number of modifier features you utilize.
1878 The wrapping method does it's best to B<only> do as much work as it
1879 absolutely needs to. In order to do this we have moved some of the
1880 performance costs to set-up time, where they are easier to amortize.
1882 All this said, our benchmarks have indicated the following:
1884 simple wrapper with no modifiers 100% slower
1885 simple wrapper with simple before modifier 400% slower
1886 simple wrapper with simple after modifier 450% slower
1887 simple wrapper with simple around modifier 500-550% slower
1888 simple wrapper with all 3 modifiers 1100% slower
1890 These numbers may seem daunting, but you must remember, every feature
1891 comes with some cost. To put things in perspective, just doing a
1892 simple C<AUTOLOAD> which does nothing but extract the name of the
1893 method called and return it costs about 400% over a normal method
1898 =item B<< $metaclass->add_before_method_modifier($method_name, $code) >>
1900 This wraps the specified method with the supplied subroutine
1901 reference. The modifier will be called as a method itself, and will
1902 receive the same arguments as are passed to the method.
1904 When the modifier exits, the wrapped method will be called.
1906 The return value of the modifier will be ignored.
1908 =item B<< $metaclass->add_after_method_modifier($method_name, $code) >>
1910 This wraps the specified method with the supplied subroutine
1911 reference. The modifier will be called as a method itself, and will
1912 receive the same arguments as are passed to the method.
1914 When the wrapped methods exits, the modifier will be called.
1916 The return value of the modifier will be ignored.
1918 =item B<< $metaclass->add_around_method_modifier($method_name, $code) >>
1920 This wraps the specified method with the supplied subroutine
1923 The first argument passed to the modifier will be a subroutine
1924 reference to the wrapped method. The second argument is the object,
1925 and after that come any arguments passed when the method is called.
1927 The around modifier can choose to call the original method, as well as
1928 what arguments to pass if it does so.
1930 The return value of the modifier is what will be seen by the caller.
1934 =head2 Introspection
1938 =item B<< Class::MOP::Class->meta >>
1940 This will return a L<Class::MOP::Class> instance for this class.
1942 It should also be noted that L<Class::MOP> will actually bootstrap
1943 this module by installing a number of attribute meta-objects into its
1950 Stevan Little E<lt>stevan@iinteractive.comE<gt>
1952 =head1 COPYRIGHT AND LICENSE
1954 Copyright 2006-2009 by Infinity Interactive, Inc.
1956 L<http://www.iinteractive.com>
1958 This library is free software; you can redistribute it and/or modify
1959 it under the same terms as Perl itself.