2 package Class::MOP::Class;
7 use Class::MOP::Instance;
8 use Class::MOP::Method::Wrapped;
9 use Class::MOP::Method::Accessor;
10 use Class::MOP::Method::Constructor;
13 use Scalar::Util 'blessed', 'reftype', 'weaken';
14 use Sub::Name 'subname';
15 use Devel::GlobalDestruction 'in_global_destruction';
17 our $VERSION = '0.89';
18 $VERSION = eval $VERSION;
19 our $AUTHORITY = 'cpan:STEVAN';
21 use base 'Class::MOP::Module';
31 $package_name = shift;
34 $package_name = $options{package};
37 ($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 $meta->is_anon_class;
111 return Class::MOP::Class->initialize($class)->new_object(@_)
112 if $class ne __PACKAGE__;
114 my $options = @_ == 1 ? $_[0] : {@_};
117 # inherited from Class::MOP::Package
118 'package' => $options->{package},
121 # since the following attributes will
122 # actually be loaded from the symbol
123 # table, and actually bypass the instance
124 # entirely, we can just leave these things
125 # listed here for reference, because they
126 # should not actually have a value associated
128 'namespace' => \undef,
130 # inherited from Class::MOP::Module
132 'authority' => \undef,
134 # defined in Class::MOP::Class
135 'superclasses' => \undef,
139 'attribute_metaclass' =>
140 ( $options->{'attribute_metaclass'} || 'Class::MOP::Attribute' ),
141 'method_metaclass' =>
142 ( $options->{'method_metaclass'} || 'Class::MOP::Method' ),
143 'wrapped_method_metaclass' => (
144 $options->{'wrapped_method_metaclass'}
145 || 'Class::MOP::Method::Wrapped'
147 'instance_metaclass' =>
148 ( $options->{'instance_metaclass'} || 'Class::MOP::Instance' ),
149 'immutable_trait' => (
150 $options->{'immutable_trait'}
151 || 'Class::MOP::Class::Immutable::Trait'
153 'constructor_name' => ( $options->{constructor_name} || 'new' ),
154 'constructor_class' => (
155 $options->{constructor_class} || 'Class::MOP::Method::Constructor'
157 'destructor_class' => $options->{destructor_class},
161 sub reset_package_cache_flag { (shift)->{'_package_cache_flag'} = undef }
162 sub update_package_cache_flag {
165 # we can manually update the cache number
166 # since we are actually adding the method
167 # to our cache as well. This avoids us
168 # having to regenerate the method_map.
170 $self->{'_package_cache_flag'} = Class::MOP::check_package_cache_flag($self->name);
174 sub check_metaclass_compatibility {
175 Carp::cluck('The check_metaclass_compatibility method has been made private.'
176 . " The public version is deprecated and will be removed in a future release.\n");
177 shift->_check_metaclass_compatibility(@_);
180 sub _check_metaclass_compatibility {
183 # this is always okay ...
184 return if ref($self) eq 'Class::MOP::Class' &&
185 $self->instance_metaclass eq 'Class::MOP::Instance';
187 my @class_list = $self->linearized_isa;
188 shift @class_list; # shift off $self->name
190 foreach my $superclass_name (@class_list) {
191 my $super_meta = Class::MOP::get_metaclass_by_name($superclass_name) || next;
194 # we need to deal with the possibility
195 # of class immutability here, and then
196 # get the name of the class appropriately
198 = $super_meta->is_immutable
199 ? $super_meta->get_mutable_metaclass_name()
202 ($self->isa($super_meta_type))
203 || confess "The metaclass of " . $self->name . " ("
204 . (ref($self)) . ")" . " is not compatible with the " .
205 "metaclass of its superclass, ".$superclass_name . " ("
206 . ($super_meta_type) . ")";
208 # we also need to check that instance metaclasses
209 # are compatibile in the same the class.
210 ($self->instance_metaclass->isa($super_meta->instance_metaclass))
211 || confess "The instance metaclass for " . $self->name . " (" . ($self->instance_metaclass) . ")" .
212 " is not compatible with the " .
213 "instance metaclass of its superclass, " . $superclass_name . " (" . ($super_meta->instance_metaclass) . ")";
221 # this should be sufficient, if you have a
222 # use case where it is not, write a test and
224 my $ANON_CLASS_SERIAL = 0;
227 # we need a sufficiently annoying prefix
228 # this should suffice for now, this is
229 # used in a couple of places below, so
230 # need to put it up here for now.
231 my $ANON_CLASS_PREFIX = 'Class::MOP::Class::__ANON__::SERIAL::';
235 no warnings 'uninitialized';
236 $self->name =~ /^$ANON_CLASS_PREFIX/o;
239 sub create_anon_class {
240 my ($class, %options) = @_;
241 my $package_name = $ANON_CLASS_PREFIX . ++$ANON_CLASS_SERIAL;
242 return $class->create($package_name, %options);
246 # this will only get called for
247 # anon-classes, all other calls
248 # are assumed to occur during
249 # global destruction and so don't
250 # really need to be handled explicitly
254 return if in_global_destruction(); # it'll happen soon anyway and this just makes things more complicated
256 no warnings 'uninitialized';
257 my $name = $self->name;
258 return unless $name =~ /^$ANON_CLASS_PREFIX/o;
259 # Moose does a weird thing where it replaces the metaclass for
260 # class when fixing metaclass incompatibility. In that case,
261 # we don't want to clean out the namespace now. We can detect
262 # that because Moose will explicitly update the singleton
263 # cache in Class::MOP.
264 my $current_meta = Class::MOP::get_metaclass_by_name($name);
265 return if $current_meta ne $self;
267 my ($serial_id) = ($name =~ /^$ANON_CLASS_PREFIX(\d+)/o);
269 @{$name . '::ISA'} = ();
270 %{$name . '::'} = ();
271 delete ${$ANON_CLASS_PREFIX}{$serial_id . '::'};
273 Class::MOP::remove_metaclass_by_name($name);
278 # creating classes with MOP ...
281 my ( $class, @args ) = @_;
283 unshift @args, 'package' if @args % 2 == 1;
285 my (%options) = @args;
286 my $package_name = $options{package};
288 (ref $options{superclasses} eq 'ARRAY')
289 || confess "You must pass an ARRAY ref of superclasses"
290 if exists $options{superclasses};
292 (ref $options{attributes} eq 'ARRAY')
293 || confess "You must pass an ARRAY ref of attributes"
294 if exists $options{attributes};
296 (ref $options{methods} eq 'HASH')
297 || confess "You must pass a HASH ref of methods"
298 if exists $options{methods};
300 my (%initialize_options) = @args;
301 delete @initialize_options{qw(
309 my $meta = $class->initialize( $package_name => %initialize_options );
311 $meta->_instantiate_module( $options{version}, $options{authority} );
314 $meta->add_method('meta' => sub {
315 $class->initialize(ref($_[0]) || $_[0]);
318 $meta->superclasses(@{$options{superclasses}})
319 if exists $options{superclasses};
321 # process attributes first, so that they can
322 # install accessors, but locally defined methods
323 # can then overwrite them. It is maybe a little odd, but
324 # I think this should be the order of things.
325 if (exists $options{attributes}) {
326 foreach my $attr (@{$options{attributes}}) {
327 $meta->add_attribute($attr);
330 if (exists $options{methods}) {
331 foreach my $method_name (keys %{$options{methods}}) {
332 $meta->add_method($method_name, $options{methods}->{$method_name});
341 # all these attribute readers will be bootstrapped
342 # away in the Class::MOP bootstrap section
344 sub get_attribute_map { $_[0]->{'attributes'} }
345 sub attribute_metaclass { $_[0]->{'attribute_metaclass'} }
346 sub method_metaclass { $_[0]->{'method_metaclass'} }
347 sub wrapped_method_metaclass { $_[0]->{'wrapped_method_metaclass'} }
348 sub instance_metaclass { $_[0]->{'instance_metaclass'} }
349 sub immutable_trait { $_[0]->{'immutable_trait'} }
350 sub constructor_class { $_[0]->{'constructor_class'} }
351 sub constructor_name { $_[0]->{'constructor_name'} }
352 sub destructor_class { $_[0]->{'destructor_class'} }
354 sub _method_map { $_[0]->{'methods'} }
356 # Instance Construction & Cloning
362 # we need to protect the integrity of the
363 # Class::MOP::Class singletons here, so we
364 # delegate this to &construct_class_instance
365 # which will deal with the singletons
366 return $class->_construct_class_instance(@_)
367 if $class->name->isa('Class::MOP::Class');
368 return $class->_construct_instance(@_);
371 sub construct_instance {
372 Carp::cluck('The construct_instance method has been made private.'
373 . " The public version is deprecated and will be removed in a future release.\n");
374 shift->_construct_instance(@_);
377 sub _construct_instance {
379 my $params = @_ == 1 ? $_[0] : {@_};
380 my $meta_instance = $class->get_meta_instance();
382 # the code below is almost certainly incorrect
383 # but this is foreign inheritance, so we might
384 # have to kludge it in the end.
385 my $instance = $params->{__INSTANCE__} || $meta_instance->create_instance();
386 foreach my $attr ($class->get_all_attributes()) {
387 $attr->initialize_instance_slot($meta_instance, $instance, $params);
390 # this will only work for a HASH instance type
391 if ($class->is_anon_class) {
392 (reftype($instance) eq 'HASH')
393 || confess "Currently only HASH based instances are supported with instance of anon-classes";
395 # At some point we should make this official
396 # as a reserved slot name, but right now I am
397 # going to keep it here.
398 # my $RESERVED_MOP_SLOT = '__MOP__';
399 $instance->{'__MOP__'} = $class;
405 sub get_meta_instance {
407 $self->{'_meta_instance'} ||= $self->_create_meta_instance();
410 sub create_meta_instance {
411 Carp::cluck('The create_meta_instance method has been made private.'
412 . " The public version is deprecated and will be removed in a future release.\n");
413 shift->_create_meta_instance(@_);
416 sub _create_meta_instance {
419 my $instance = $self->instance_metaclass->new(
420 associated_metaclass => $self,
421 attributes => [ $self->get_all_attributes() ],
424 $self->add_meta_instance_dependencies()
425 if $instance->is_dependent_on_superclasses();
432 my $instance = shift;
433 (blessed($instance) && $instance->isa($class->name))
434 || confess "You must pass an instance of the metaclass (" . (ref $class ? $class->name : $class) . "), not ($instance)";
437 # we need to protect the integrity of the
438 # Class::MOP::Class singletons here, they
439 # should not be cloned.
440 return $instance if $instance->isa('Class::MOP::Class');
441 $class->_clone_instance($instance, @_);
445 Carp::cluck('The clone_instance method has been made private.'
446 . " The public version is deprecated and will be removed in a future release.\n");
447 shift->_clone_instance(@_);
450 sub _clone_instance {
451 my ($class, $instance, %params) = @_;
453 || confess "You can only clone instances, ($instance) is not a blessed instance";
454 my $meta_instance = $class->get_meta_instance();
455 my $clone = $meta_instance->clone_instance($instance);
456 foreach my $attr ($class->get_all_attributes()) {
457 if ( defined( my $init_arg = $attr->init_arg ) ) {
458 if (exists $params{$init_arg}) {
459 $attr->set_value($clone, $params{$init_arg});
466 sub rebless_instance {
467 my ($self, $instance, %params) = @_;
469 my $old_metaclass = Class::MOP::class_of($instance);
471 my $old_class = $old_metaclass ? $old_metaclass->name : blessed($instance);
472 $self->name->isa($old_class)
473 || confess "You may rebless only into a subclass of ($old_class), of which (". $self->name .") isn't.";
475 $old_metaclass->rebless_instance_away($instance, $self, %params)
478 my $meta_instance = $self->get_meta_instance();
481 # we use $_[1] here because of t/306_rebless_overload.t regressions on 5.8.8
482 $meta_instance->rebless_instance_structure($_[1], $self);
484 foreach my $attr ( $self->get_all_attributes ) {
485 if ( $attr->has_value($instance) ) {
486 if ( defined( my $init_arg = $attr->init_arg ) ) {
487 $params{$init_arg} = $attr->get_value($instance)
488 unless exists $params{$init_arg};
491 $attr->set_value($instance, $attr->get_value($instance));
496 foreach my $attr ($self->get_all_attributes) {
497 $attr->initialize_instance_slot($meta_instance, $instance, \%params);
503 sub rebless_instance_away {
504 # this intentionally does nothing, it is just a hook
511 my $var_spec = { sigil => '@', type => 'ARRAY', name => 'ISA' };
514 @{$self->get_package_symbol($var_spec)} = @supers;
517 # on 5.8 and below, we need to call
518 # a method to get Perl to detect
519 # a cycle in the class hierarchy
520 my $class = $self->name;
524 # we need to check the metaclass
525 # compatibility here so that we can
526 # be sure that the superclass is
527 # not potentially creating an issues
528 # we don't know about
530 $self->_check_metaclass_compatibility();
531 $self->_superclasses_updated();
533 @{$self->get_package_symbol($var_spec)};
536 sub _superclasses_updated {
538 $self->update_meta_instance_dependencies();
543 my $super_class = $self->name;
545 return @{ $super_class->mro::get_isarev() };
548 sub direct_subclasses {
550 my $super_class = $self->name;
555 } Class::MOP::Class->initialize($_)->superclasses
560 return @{ mro::get_linear_isa( (shift)->name ) };
563 sub class_precedence_list {
565 my $name = $self->name;
567 unless (Class::MOP::IS_RUNNING_ON_5_10()) {
569 # We need to check for circular inheritance here
570 # if we are are not on 5.10, cause 5.8 detects it
571 # late. This will do nothing if all is well, and
572 # blow up otherwise. Yes, it's an ugly hack, better
573 # suggestions are welcome.
575 ($name || return)->isa('This is a test for circular inheritance')
578 # if our mro is c3, we can
579 # just grab the linear_isa
580 if (mro::get_mro($name) eq 'c3') {
581 return @{ mro::get_linear_isa($name) }
585 # we can't grab the linear_isa for dfs
586 # since it has all the duplicates
591 $self->initialize($_)->class_precedence_list()
592 } $self->superclasses()
599 sub wrap_method_body {
600 my ( $self, %args ) = @_;
602 ('CODE' eq ref $args{body})
603 || confess "Your code block must be a CODE reference";
605 $self->method_metaclass->wrap(
606 package_name => $self->name,
612 my ($self, $method_name, $method) = @_;
613 (defined $method_name && $method_name)
614 || confess "You must define a method name";
617 if (blessed($method)) {
618 $body = $method->body;
619 if ($method->package_name ne $self->name) {
620 $method = $method->clone(
621 package_name => $self->name,
623 ) if $method->can('clone');
626 $method->attach_to_class($self);
627 $self->_method_map->{$method_name} = $method;
630 # If a raw code reference is supplied, its method object is not created.
631 # The method object won't be created until required.
636 my ( $current_package, $current_name ) = Class::MOP::get_code_info($body);
638 if ( !defined $current_name || $current_name eq '__ANON__' ) {
639 my $full_method_name = ($self->name . '::' . $method_name);
640 subname($full_method_name => $body);
643 $self->add_package_symbol(
644 { sigil => '&', type => 'CODE', name => $method_name },
650 my $fetch_and_prepare_method = sub {
651 my ($self, $method_name) = @_;
652 my $wrapped_metaclass = $self->wrapped_method_metaclass;
654 my $method = $self->get_method($method_name);
655 # if we dont have local ...
657 # try to find the next method
658 $method = $self->find_next_method_by_name($method_name);
659 # die if it does not exist
661 || confess "The method '$method_name' was not found in the inheritance hierarchy for " . $self->name;
662 # and now make sure to wrap it
663 # even if it is already wrapped
664 # because we need a new sub ref
665 $method = $wrapped_metaclass->wrap($method);
668 # now make sure we wrap it properly
669 $method = $wrapped_metaclass->wrap($method)
670 unless $method->isa($wrapped_metaclass);
672 $self->add_method($method_name => $method);
676 sub add_before_method_modifier {
677 my ($self, $method_name, $method_modifier) = @_;
678 (defined $method_name && $method_name)
679 || confess "You must pass in a method name";
680 my $method = $fetch_and_prepare_method->($self, $method_name);
681 $method->add_before_modifier(
682 subname(':before' => $method_modifier)
686 sub add_after_method_modifier {
687 my ($self, $method_name, $method_modifier) = @_;
688 (defined $method_name && $method_name)
689 || confess "You must pass in a method name";
690 my $method = $fetch_and_prepare_method->($self, $method_name);
691 $method->add_after_modifier(
692 subname(':after' => $method_modifier)
696 sub add_around_method_modifier {
697 my ($self, $method_name, $method_modifier) = @_;
698 (defined $method_name && $method_name)
699 || confess "You must pass in a method name";
700 my $method = $fetch_and_prepare_method->($self, $method_name);
701 $method->add_around_modifier(
702 subname(':around' => $method_modifier)
707 # the methods above used to be named like this:
708 # ${pkg}::${method}:(before|after|around)
709 # but this proved problematic when using one modifier
710 # to wrap multiple methods (something which is likely
711 # to happen pretty regularly IMO). So instead of naming
712 # it like this, I have chosen to just name them purely
713 # with their modifier names, like so:
714 # :(before|after|around)
715 # The fact is that in a stack trace, it will be fairly
716 # evident from the context what method they are attached
717 # to, and so don't need the fully qualified name.
721 Carp::cluck("The alias_method method is deprecated. Use add_method instead.\n");
723 shift->add_method(@_);
727 my ( $self, $code ) = @_;
729 my ( $code_package, $code_name ) = Class::MOP::get_code_info($code);
731 return $code_package && $code_package eq $self->name
732 || ( $code_package eq 'constant' && $code_name eq '__ANON__' );
736 my ($self, $method_name) = @_;
737 (defined $method_name && $method_name)
738 || confess "You must define a method name";
740 return defined($self->get_method($method_name));
744 my ($self, $method_name) = @_;
745 (defined $method_name && $method_name)
746 || confess "You must define a method name";
748 my $method_map = $self->_method_map;
749 my $method_object = $method_map->{$method_name};
750 my $code = $self->get_package_symbol({
751 name => $method_name,
756 unless ( $method_object && $method_object->body == ( $code || 0 ) ) {
757 if ( $code && $self->_code_is_mine($code) ) {
758 $method_object = $method_map->{$method_name}
759 = $self->wrap_method_body(
761 name => $method_name,
762 associated_metaclass => $self,
766 delete $method_map->{$method_name};
771 return $method_object;
775 my ($self, $method_name) = @_;
776 (defined $method_name && $method_name)
777 || confess "You must define a method name";
779 my $removed_method = delete $self->get_method_map->{$method_name};
781 $self->remove_package_symbol(
782 { sigil => '&', type => 'CODE', name => $method_name }
785 $removed_method->detach_from_class if $removed_method;
787 $self->update_package_cache_flag; # still valid, since we just removed the method from the map
789 return $removed_method;
792 sub get_method_list {
794 return grep { $self->has_method($_) } keys %{ $self->namespace };
797 sub find_method_by_name {
798 my ($self, $method_name) = @_;
799 (defined $method_name && $method_name)
800 || confess "You must define a method name to find";
801 foreach my $class ($self->linearized_isa) {
802 my $method = $self->initialize($class)->get_method($method_name);
803 return $method if defined $method;
808 sub get_all_methods {
810 my %methods = map { %{ $self->initialize($_)->get_method_map } } reverse $self->linearized_isa;
811 return values %methods;
814 sub compute_all_applicable_methods {
815 Carp::cluck('The compute_all_applicable_methods method is deprecated.'
816 . " Use get_all_methods instead.\n");
821 class => $_->package_name,
822 code => $_, # sigh, overloading
824 } shift->get_all_methods(@_);
827 sub get_all_method_names {
830 return grep { !$uniq{$_}++ } map { $self->initialize($_)->get_method_list } $self->linearized_isa;
833 sub find_all_methods_by_name {
834 my ($self, $method_name) = @_;
835 (defined $method_name && $method_name)
836 || confess "You must define a method name to find";
838 foreach my $class ($self->linearized_isa) {
839 # fetch the meta-class ...
840 my $meta = $self->initialize($class);
842 name => $method_name,
844 code => $meta->get_method($method_name)
845 } if $meta->has_method($method_name);
850 sub find_next_method_by_name {
851 my ($self, $method_name) = @_;
852 (defined $method_name && $method_name)
853 || confess "You must define a method name to find";
854 my @cpl = $self->linearized_isa;
855 shift @cpl; # discard ourselves
856 foreach my $class (@cpl) {
857 my $method = $self->initialize($class)->get_method($method_name);
858 return $method if defined $method;
867 # either we have an attribute object already
868 # or we need to create one from the args provided
869 my $attribute = blessed($_[0]) ? $_[0] : $self->attribute_metaclass->new(@_);
870 # make sure it is derived from the correct type though
871 ($attribute->isa('Class::MOP::Attribute'))
872 || confess "Your attribute must be an instance of Class::MOP::Attribute (or a subclass)";
874 # first we attach our new attribute
875 # because it might need certain information
876 # about the class which it is attached to
877 $attribute->attach_to_class($self);
879 my $attr_name = $attribute->name;
881 # then we remove attributes of a conflicting
882 # name here so that we can properly detach
883 # the old attr object, and remove any
884 # accessors it would have generated
885 if ( $self->has_attribute($attr_name) ) {
886 $self->remove_attribute($attr_name);
888 $self->invalidate_meta_instances();
891 # get our count of previously inserted attributes and
892 # increment by one so this attribute knows its order
893 my $order = (scalar keys %{$self->get_attribute_map});
894 $attribute->_set_insertion_order($order);
896 # then onto installing the new accessors
897 $self->get_attribute_map->{$attr_name} = $attribute;
899 # invalidate package flag here
903 eval { $attribute->install_accessors() };
907 $self->remove_attribute($attr_name);
914 sub update_meta_instance_dependencies {
917 if ( $self->{meta_instance_dependencies} ) {
918 return $self->add_meta_instance_dependencies;
922 sub add_meta_instance_dependencies {
925 $self->remove_meta_instance_dependencies;
927 my @attrs = $self->get_all_attributes();
930 my @classes = grep { not $seen{$_->name}++ } map { $_->associated_class } @attrs;
932 foreach my $class ( @classes ) {
933 $class->add_dependent_meta_instance($self);
936 $self->{meta_instance_dependencies} = \@classes;
939 sub remove_meta_instance_dependencies {
942 if ( my $classes = delete $self->{meta_instance_dependencies} ) {
943 foreach my $class ( @$classes ) {
944 $class->remove_dependent_meta_instance($self);
954 sub add_dependent_meta_instance {
955 my ( $self, $metaclass ) = @_;
956 push @{ $self->{dependent_meta_instances} }, $metaclass;
959 sub remove_dependent_meta_instance {
960 my ( $self, $metaclass ) = @_;
961 my $name = $metaclass->name;
962 @$_ = grep { $_->name ne $name } @$_ for $self->{dependent_meta_instances};
965 sub invalidate_meta_instances {
967 $_->invalidate_meta_instance() for $self, @{ $self->{dependent_meta_instances} };
970 sub invalidate_meta_instance {
972 undef $self->{_meta_instance};
976 my ($self, $attribute_name) = @_;
977 (defined $attribute_name && $attribute_name)
978 || confess "You must define an attribute name";
979 exists $self->get_attribute_map->{$attribute_name};
983 my ($self, $attribute_name) = @_;
984 (defined $attribute_name && $attribute_name)
985 || confess "You must define an attribute name";
986 return $self->get_attribute_map->{$attribute_name}
988 # this will return undef anyway, so no need ...
989 # if $self->has_attribute($attribute_name);
993 sub remove_attribute {
994 my ($self, $attribute_name) = @_;
995 (defined $attribute_name && $attribute_name)
996 || confess "You must define an attribute name";
997 my $removed_attribute = $self->get_attribute_map->{$attribute_name};
998 return unless defined $removed_attribute;
999 delete $self->get_attribute_map->{$attribute_name};
1000 $self->invalidate_meta_instances();
1001 $removed_attribute->remove_accessors();
1002 $removed_attribute->detach_from_class();
1003 return $removed_attribute;
1006 sub get_attribute_list {
1008 keys %{$self->get_attribute_map};
1011 sub get_all_attributes {
1013 my %attrs = map { %{ $self->initialize($_)->get_attribute_map } } reverse $self->linearized_isa;
1014 return values %attrs;
1017 sub compute_all_applicable_attributes {
1018 Carp::cluck('The compute_all_applicable_attributes method has been deprecated.'
1019 . " Use get_all_attributes instead.\n");
1021 shift->get_all_attributes(@_);
1024 sub find_attribute_by_name {
1025 my ($self, $attr_name) = @_;
1026 foreach my $class ($self->linearized_isa) {
1027 # fetch the meta-class ...
1028 my $meta = $self->initialize($class);
1029 return $meta->get_attribute($attr_name)
1030 if $meta->has_attribute($attr_name);
1035 # check if we can reinitialize
1039 # if any local attr is defined
1040 return if $self->get_attribute_list;
1042 # or any non-declared methods
1043 if ( my @methods = values %{ $self->get_method_map } ) {
1044 my $metaclass = $self->method_metaclass;
1045 foreach my $method ( @methods ) {
1046 return if $method->isa("Class::MOP::Method::Generated");
1047 # FIXME do we need to enforce this too? return unless $method->isa($metaclass);
1056 sub is_mutable { 1 }
1057 sub is_immutable { 0 }
1059 sub _immutable_options {
1060 my ( $self, @args ) = @_;
1063 inline_accessors => 1,
1064 inline_constructor => 1,
1065 inline_destructor => 0,
1067 immutable_trait => $self->immutable_trait,
1068 constructor_name => $self->constructor_name,
1069 constructor_class => $self->constructor_class,
1070 destructor_class => $self->destructor_class,
1075 sub make_immutable {
1076 my ( $self, @args ) = @_;
1078 if ( $self->is_mutable ) {
1079 $self->_initialize_immutable( $self->_immutable_options(@args) );
1080 $self->_rebless_as_immutable(@args);
1091 if ( $self->is_immutable ) {
1092 my @args = $self->immutable_options;
1093 $self->_rebless_as_mutable();
1094 $self->_remove_inlined_code(@args);
1095 delete $self->{__immutable};
1103 sub _rebless_as_immutable {
1104 my ( $self, @args ) = @_;
1106 $self->{__immutable}{original_class} = ref $self;
1108 bless $self => $self->_immutable_metaclass(@args);
1111 sub _immutable_metaclass {
1112 my ( $self, %args ) = @_;
1114 if ( my $class = $args{immutable_metaclass} ) {
1118 my $trait = $args{immutable_trait} = $self->immutable_trait
1119 || confess "no immutable trait specified for $self";
1121 my $meta = $self->meta;
1122 my $meta_attr = $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 = $meta->is_immutable
1145 ? $meta->get_mutable_metaclass_name
1148 my $immutable_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 my $meth_name = $meth->name;
1157 if ( $immutable_meta->find_method_by_name( $meth_name ) ) {
1158 $immutable_meta->add_around_method_modifier( $meth_name, $meth->body );
1161 $immutable_meta->add_method( $meth_name, $meth->clone );
1165 $immutable_meta->make_immutable(
1166 inline_constructor => 0,
1167 inline_accessors => 0,
1173 sub _remove_inlined_code {
1176 $self->remove_method( $_->name ) for $self->_inlined_methods;
1178 delete $self->{__immutable}{inlined_methods};
1181 sub _inlined_methods { @{ $_[0]{__immutable}{inlined_methods} || [] } }
1183 sub _add_inlined_method {
1184 my ( $self, $method ) = @_;
1186 push @{ $self->{__immutable}{inlined_methods} ||= [] }, $method;
1189 sub _initialize_immutable {
1190 my ( $self, %args ) = @_;
1192 $self->{__immutable}{options} = \%args;
1193 $self->_install_inlined_code(%args);
1196 sub _install_inlined_code {
1197 my ( $self, %args ) = @_;
1200 $self->_inline_accessors(%args) if $args{inline_accessors};
1201 $self->_inline_constructor(%args) if $args{inline_constructor};
1202 $self->_inline_destructor(%args) if $args{inline_destructor};
1205 sub _rebless_as_mutable {
1208 bless $self, $self->get_mutable_metaclass_name;
1213 sub _inline_accessors {
1216 foreach my $attr_name ( $self->get_attribute_list ) {
1217 $self->get_attribute($attr_name)->install_accessors(1);
1221 sub _inline_constructor {
1222 my ( $self, %args ) = @_;
1224 my $name = $args{constructor_name};
1226 if ( $self->has_method($name) && !$args{replace_constructor} ) {
1227 my $class = $self->name;
1228 warn "Not inlining a constructor for $class since it defines"
1229 . " its own constructor.\n"
1230 . "If you are certain you don't need to inline your"
1231 . " constructor, specify inline_constructor => 0 in your"
1232 . " call to $class->meta->make_immutable\n";
1236 my $constructor_class = $args{constructor_class};
1238 Class::MOP::load_class($constructor_class);
1240 my $constructor = $constructor_class->new(
1244 package_name => $self->name,
1248 if ( $args{replace_constructor} or $constructor->can_be_inlined ) {
1249 $self->add_method( $name => $constructor );
1250 $self->_add_inlined_method($constructor);
1254 sub _inline_destructor {
1255 my ( $self, %args ) = @_;
1257 ( exists $args{destructor_class} && defined $args{destructor_class} )
1258 || confess "The 'inline_destructor' option is present, but "
1259 . "no destructor class was specified";
1261 if ( $self->has_method('DESTROY') && ! $args{replace_destructor} ) {
1262 my $class = $self->name;
1263 warn "Not inlining a destructor for $class since it defines"
1264 . " its own destructor.\n";
1268 my $destructor_class = $args{destructor_class};
1270 Class::MOP::load_class($destructor_class);
1272 return unless $destructor_class->is_needed($self);
1274 my $destructor = $destructor_class->new(
1277 package_name => $self->name,
1281 if ( $args{replace_destructor} or $destructor->can_be_inlined ) {
1282 $self->add_method( 'DESTROY' => $destructor );
1283 $self->_add_inlined_method($destructor);
1295 Class::MOP::Class - Class Meta Object
1299 # assuming that class Foo
1300 # has been defined, you can
1302 # use this for introspection ...
1304 # add a method to Foo ...
1305 Foo->meta->add_method( 'bar' => sub {...} )
1307 # get a list of all the classes searched
1308 # the method dispatcher in the correct order
1309 Foo->meta->class_precedence_list()
1311 # remove a method from Foo
1312 Foo->meta->remove_method('bar');
1314 # or use this to actually create classes ...
1316 Class::MOP::Class->create(
1319 superclasses => ['Foo'],
1321 Class::MOP::Attribute->new('$bar'),
1322 Class::MOP::Attribute->new('$baz'),
1325 calculate_bar => sub {...},
1326 construct_baz => sub {...}
1333 The Class Protocol is the largest and most complex part of the
1334 Class::MOP meta-object protocol. It controls the introspection and
1335 manipulation of Perl 5 classes, and it can create them as well. The
1336 best way to understand what this module can do, is to read the
1337 documentation for each of its methods.
1341 C<Class::MOP::Class> is a subclass of L<Class::MOP::Module>.
1345 =head2 Class construction
1347 These methods all create new C<Class::MOP::Class> objects. These
1348 objects can represent existing classes, or they can be used to create
1349 new classes from scratch.
1351 The metaclass object for a given class is a singleton. If you attempt
1352 to create a metaclass for the same class twice, you will just get the
1357 =item B<< Class::MOP::Class->create($package_name, %options) >>
1359 This method creates a new C<Class::MOP::Class> object with the given
1360 package name. It accepts a number of options.
1366 An optional version number for the newly created package.
1370 An optional authority for the newly created package.
1372 =item * superclasses
1374 An optional array reference of superclass names.
1378 An optional hash reference of methods for the class. The keys of the
1379 hash reference are method names, and values are subroutine references.
1383 An optional array reference of L<Class::MOP::Attribute> objects.
1387 =item B<< Class::MOP::Class->create_anon_class(%options) >>
1389 This method works just like C<< Class::MOP::Class->create >> but it
1390 creates an "anonymous" class. In fact, the class does have a name, but
1391 that name is a unique name generated internally by this module.
1393 It accepts the same C<superclasses>, C<methods>, and C<attributes>
1394 parameters that C<create> accepts.
1396 Anonymous classes are destroyed once the metaclass they are attached
1397 to goes out of scope, and will be removed from Perl's internal symbol
1400 All instances of an anonymous class keep a special reference to the
1401 metaclass object, which prevents the metaclass from going out of scope
1402 while any instances exist.
1404 This only works if the instance if based on a hash reference, however.
1406 =item B<< Class::MOP::Class->initialize($package_name, %options) >>
1408 This method will initialize a C<Class::MOP::Class> object for the
1409 named package. Unlike C<create>, this method I<will not> create a new
1412 The purpose of this method is to retrieve a C<Class::MOP::Class>
1413 object for introspecting an existing class.
1415 If an existing C<Class::MOP::Class> object exists for the named
1416 package, it will be returned, and any options provided will be
1419 If the object does not yet exist, it will be created.
1421 The valid options that can be passed to this method are
1422 C<attribute_metaclass>, C<method_metaclass>,
1423 C<wrapped_method_metaclass>, and C<instance_metaclass>. These are all
1424 optional, and default to the appropriate class in the C<Class::MOP>
1429 =head2 Object instance construction and cloning
1431 These methods are all related to creating and/or cloning object
1436 =item B<< $metaclass->clone_object($instance, %params) >>
1438 This method clones an existing object instance. Any parameters you
1439 provide are will override existing attribute values in the object.
1441 This is a convenience method for cloning an object instance, then
1442 blessing it into the appropriate package.
1444 You could implement a clone method in your class, using this method:
1447 my ($self, %params) = @_;
1448 $self->meta->clone_object($self, %params);
1451 =item B<< $metaclass->rebless_instance($instance, %params) >>
1453 This method changes the class of C<$instance> to the metaclass's class.
1455 You can only rebless an instance into a subclass of its current
1456 class. If you pass any additional parameters, these will be treated
1457 like constructor parameters and used to initialize the object's
1458 attributes. Any existing attributes that are already set will be
1461 Before reblessing the instance, this method will call
1462 C<rebless_instance_away> on the instance's current metaclass. This method
1463 will be passed the instance, the new metaclass, and any parameters
1464 specified to C<rebless_instance>. By default, C<rebless_instance_away>
1465 does nothing; it is merely a hook.
1467 =item B<< $metaclass->new_object(%params) >>
1469 This method is used to create a new object of the metaclass's
1470 class. Any parameters you provide are used to initialize the
1471 instance's attributes. A special C<__INSTANCE__> key can be passed to
1472 provide an already generated instance, rather than having Class::MOP
1473 generate it for you. This is mostly useful for using Class::MOP with
1474 foreign classes, which generally generate instances using their own
1477 =item B<< $metaclass->instance_metaclass >>
1479 Returns the class name of the instance metaclass, see
1480 L<Class::MOP::Instance> for more information on the instance
1483 =item B<< $metaclass->get_meta_instance >>
1485 Returns an instance of the C<instance_metaclass> to be used in the
1486 construction of a new instance of the class.
1490 =head2 Informational predicates
1492 These are a few predicate methods for asking information about the
1497 =item B<< $metaclass->is_anon_class >>
1499 This returns true if the class was created by calling C<<
1500 Class::MOP::Class->create_anon_class >>.
1502 =item B<< $metaclass->is_mutable >>
1504 This returns true if the class is still mutable.
1506 =item B<< $metaclass->is_immutable >>
1508 This returns true if the class has been made immutable.
1510 =item B<< $metaclass->is_pristine >>
1512 A class is I<not> pristine if it has non-inherited attributes or if it
1513 has any generated methods.
1517 =head2 Inheritance Relationships
1521 =item B<< $metaclass->superclasses(@superclasses) >>
1523 This is a read-write accessor which represents the superclass
1524 relationships of the metaclass's class.
1526 This is basically sugar around getting and setting C<@ISA>.
1528 =item B<< $metaclass->class_precedence_list >>
1530 This returns a list of all of the class's ancestor classes. The
1531 classes are returned in method dispatch order.
1533 =item B<< $metaclass->linearized_isa >>
1535 This returns a list based on C<class_precedence_list> but with all
1538 =item B<< $metaclass->subclasses >>
1540 This returns a list of all subclasses for this class, even indirect
1543 =item B<< $metaclass->direct_subclasses >>
1545 This returns a list of immediate subclasses for this class, which does not
1546 include indirect subclasses.
1550 =head2 Method introspection and creation
1552 These methods allow you to introspect a class's methods, as well as
1553 add, remove, or change methods.
1555 Determining what is truly a method in a Perl 5 class requires some
1556 heuristics (aka guessing).
1558 Methods defined outside the package with a fully qualified name (C<sub
1559 Package::name { ... }>) will be included. Similarly, methods named
1560 with a fully qualified name using L<Sub::Name> are also included.
1562 However, we attempt to ignore imported functions.
1564 Ultimately, we are using heuristics to determine what truly is a
1565 method in a class, and these heuristics may get the wrong answer in
1566 some edge cases. However, for most "normal" cases the heuristics work
1571 =item B<< $metaclass->get_method($method_name) >>
1573 This will return a L<Class::MOP::Method> for the specified
1574 C<$method_name>. If the class does not have the specified method, it
1577 =item B<< $metaclass->has_method($method_name) >>
1579 Returns a boolean indicating whether or not the class defines the
1580 named method. It does not include methods inherited from parent
1583 =item B<< $metaclass->get_method_map >>
1585 Returns a hash reference representing the methods defined in this
1586 class. The keys are method names and the values are
1587 L<Class::MOP::Method> objects.
1589 =item B<< $metaclass->get_method_list >>
1591 This will return a list of method I<names> for all methods defined in
1594 =item B<< $metaclass->get_all_methods >>
1596 This will traverse the inheritance hierarchy and return a list of all
1597 the L<Class::MOP::Method> objects for this class and its parents.
1599 =item B<< $metaclass->find_method_by_name($method_name) >>
1601 This will return a L<Class::MOP::Method> for the specified
1602 C<$method_name>. If the class does not have the specified method, it
1605 Unlike C<get_method>, this method I<will> look for the named method in
1608 =item B<< $metaclass->get_all_method_names >>
1610 This will return a list of method I<names> for all of this class's
1611 methods, including inherited methods.
1613 =item B<< $metaclass->find_all_methods_by_name($method_name) >>
1615 This method looks for the named method in the class and all of its
1616 parents. It returns every matching method it finds in the inheritance
1617 tree, so it returns a list of methods.
1619 Each method is returned as a hash reference with three keys. The keys
1620 are C<name>, C<class>, and C<code>. The C<code> key has a
1621 L<Class::MOP::Method> object as its value.
1623 The list of methods is distinct.
1625 =item B<< $metaclass->find_next_method_by_name($method_name) >>
1627 This method returns the first method in any superclass matching the
1628 given name. It is effectively the method that C<SUPER::$method_name>
1631 =item B<< $metaclass->add_method($method_name, $method) >>
1633 This method takes a method name and a subroutine reference, and adds
1634 the method to the class.
1636 The subroutine reference can be a L<Class::MOP::Method>, and you are
1637 strongly encouraged to pass a meta method object instead of a code
1638 reference. If you do so, that object gets stored as part of the
1639 class's method map directly. If not, the meta information will have to
1640 be recreated later, and may be incorrect.
1642 If you provide a method object, this method will clone that object if
1643 the object's package name does not match the class name. This lets us
1644 track the original source of any methods added from other classes
1645 (notably Moose roles).
1647 =item B<< $metaclass->remove_method($method_name) >>
1649 Remove the named method from the class. This method returns the
1650 L<Class::MOP::Method> object for the method.
1652 =item B<< $metaclass->method_metaclass >>
1654 Returns the class name of the method metaclass, see
1655 L<Class::MOP::Method> for more information on the method metaclass.
1657 =item B<< $metaclass->wrapped_method_metaclass >>
1659 Returns the class name of the wrapped method metaclass, see
1660 L<Class::MOP::Method::Wrapped> for more information on the wrapped
1665 =head2 Attribute introspection and creation
1667 Because Perl 5 does not have a core concept of attributes in classes,
1668 we can only return information about attributes which have been added
1669 via this class's methods. We cannot discover information about
1670 attributes which are defined in terms of "regular" Perl 5 methods.
1674 =item B<< $metaclass->get_attribute($attribute_name) >>
1676 This will return a L<Class::MOP::Attribute> for the specified
1677 C<$attribute_name>. If the class does not have the specified
1678 attribute, it returns C<undef>.
1680 NOTE that get_attribute does not search superclasses, for that you
1681 need to use C<find_attribute_by_name>.
1683 =item B<< $metaclass->has_attribute($attribute_name) >>
1685 Returns a boolean indicating whether or not the class defines the
1686 named attribute. It does not include attributes inherited from parent
1689 =item B<< $metaclass->get_attribute_map >>
1691 Returns a hash reference representing the attributes defined in this
1692 class. The keys are attribute names and the values are
1693 L<Class::MOP::Attribute> objects.
1695 =item B<< $metaclass->get_attribute_list >>
1697 This will return a list of attributes I<names> for all attributes
1698 defined in this class.
1700 =item B<< $metaclass->get_all_attributes >>
1702 This will traverse the inheritance hierarchy and return a list of all
1703 the L<Class::MOP::Attribute> objects for this class and its parents.
1705 =item B<< $metaclass->find_attribute_by_name($attribute_name) >>
1707 This will return a L<Class::MOP::Attribute> for the specified
1708 C<$attribute_name>. If the class does not have the specified
1709 attribute, it returns C<undef>
1711 Unlike C<get_attribute>, this attribute I<will> look for the named
1712 attribute in superclasses.
1714 =item B<< $metaclass->add_attribute(...) >>
1716 This method accepts either an existing L<Class::MOP::Attribute>
1717 object, or parameters suitable for passing to that class's C<new>
1720 The attribute provided will be added to the class.
1722 Any accessor methods defined by the attribute will be added to the
1723 class when the attribute is added.
1725 If an attribute of the same name already exists, the old attribute
1726 will be removed first.
1728 =item B<< $metaclass->remove_attribute($attribute_name) >>
1730 This will remove the named attribute from the class, and
1731 L<Class::MOP::Attribute> object.
1733 Removing an attribute also removes any accessor methods defined by the
1736 However, note that removing an attribute will only affect I<future>
1737 object instances created for this class, not existing instances.
1739 =item B<< $metaclass->attribute_metaclass >>
1741 Returns the class name of the attribute metaclass for this class. By
1742 default, this is L<Class::MOP::Attribute>. for more information on
1746 =head2 Class Immutability
1748 Making a class immutable "freezes" the class definition. You can no
1749 longer call methods which alter the class, such as adding or removing
1750 methods or attributes.
1752 Making a class immutable lets us optimize the class by inlining some
1753 methods, and also allows us to optimize some methods on the metaclass
1756 After immutabilization, the metaclass object will cache most
1757 informational methods such as C<get_method_map> and
1758 C<get_all_attributes>. Methods which would alter the class, such as
1759 C<add_attribute>, C<add_method>, and so on will throw an error on an
1760 immutable metaclass object.
1762 The immutabilization system in L<Moose> takes much greater advantage
1763 of the inlining features than Class::MOP itself does.
1767 =item B<< $metaclass->make_immutable(%options) >>
1769 This method will create an immutable transformer and uses it to make
1770 the class and its metaclass object immutable.
1772 This method accepts the following options:
1776 =item * inline_accessors
1778 =item * inline_constructor
1780 =item * inline_destructor
1782 These are all booleans indicating whether the specified method(s)
1785 By default, accessors and the constructor are inlined, but not the
1788 =item * immutable_trait
1790 The name of a class which will be used as a parent class for the
1791 metaclass object being made immutable. This "trait" implements the
1792 post-immutability functionality of the metaclass (but not the
1793 transformation itself).
1795 This defaults to L<Class::MOP::Class::Immutable::Trait>.
1797 =item * constructor_name
1799 This is the constructor method name. This defaults to "new".
1801 =item * constructor_class
1803 The name of the method metaclass for constructors. It will be used to
1804 generate the inlined constructor. This defaults to
1805 "Class::MOP::Method::Constructor".
1807 =item * replace_constructor
1809 This is a boolean indicating whether an existing constructor should be
1810 replaced when inlining a constructor. This defaults to false.
1812 =item * destructor_class
1814 The name of the method metaclass for destructors. It will be used to
1815 generate the inlined destructor. This defaults to
1816 "Class::MOP::Method::Denstructor".
1818 =item * replace_destructor
1820 This is a boolean indicating whether an existing destructor should be
1821 replaced when inlining a destructor. This defaults to false.
1825 =item B<< $metaclass->make_mutable >>
1827 Calling this method reverse the immutabilization transformation.
1831 =head2 Method Modifiers
1833 Method modifiers are hooks which allow a method to be wrapped with
1834 I<before>, I<after> and I<around> method modifiers. Every time a
1835 method is called, it's modifiers are also called.
1837 A class can modify its own methods, as well as methods defined in
1840 =head3 How method modifiers work?
1842 Method modifiers work by wrapping the original method and then
1843 replacing it in the class's symbol table. The wrappers will handle
1844 calling all the modifiers in the appropriate order and preserving the
1845 calling context for the original method.
1847 The return values of C<before> and C<after> modifiers are
1848 ignored. This is because their purpose is B<not> to filter the input
1849 and output of the primary method (this is done with an I<around>
1852 This may seem like an odd restriction to some, but doing this allows
1853 for simple code to be added at the beginning or end of a method call
1854 without altering the function of the wrapped method or placing any
1855 extra responsibility on the code of the modifier.
1857 Of course if you have more complex needs, you can use the C<around>
1858 modifier which allows you to change both the parameters passed to the
1859 wrapped method, as well as its return value.
1861 Before and around modifiers are called in last-defined-first-called
1862 order, while after modifiers are called in first-defined-first-called
1863 order. So the call tree might looks something like this:
1875 =head3 What is the performance impact?
1877 Of course there is a performance cost associated with method
1878 modifiers, but we have made every effort to make that cost directly
1879 proportional to the number of modifier features you utilize.
1881 The wrapping method does it's best to B<only> do as much work as it
1882 absolutely needs to. In order to do this we have moved some of the
1883 performance costs to set-up time, where they are easier to amortize.
1885 All this said, our benchmarks have indicated the following:
1887 simple wrapper with no modifiers 100% slower
1888 simple wrapper with simple before modifier 400% slower
1889 simple wrapper with simple after modifier 450% slower
1890 simple wrapper with simple around modifier 500-550% slower
1891 simple wrapper with all 3 modifiers 1100% slower
1893 These numbers may seem daunting, but you must remember, every feature
1894 comes with some cost. To put things in perspective, just doing a
1895 simple C<AUTOLOAD> which does nothing but extract the name of the
1896 method called and return it costs about 400% over a normal method
1901 =item B<< $metaclass->add_before_method_modifier($method_name, $code) >>
1903 This wraps the specified method with the supplied subroutine
1904 reference. The modifier will be called as a method itself, and will
1905 receive the same arguments as are passed to the method.
1907 When the modifier exits, the wrapped method will be called.
1909 The return value of the modifier will be ignored.
1911 =item B<< $metaclass->add_after_method_modifier($method_name, $code) >>
1913 This wraps the specified method with the supplied subroutine
1914 reference. The modifier will be called as a method itself, and will
1915 receive the same arguments as are passed to the method.
1917 When the wrapped methods exits, the modifier will be called.
1919 The return value of the modifier will be ignored.
1921 =item B<< $metaclass->add_around_method_modifier($method_name, $code) >>
1923 This wraps the specified method with the supplied subroutine
1926 The first argument passed to the modifier will be a subroutine
1927 reference to the wrapped method. The second argument is the object,
1928 and after that come any arguments passed when the method is called.
1930 The around modifier can choose to call the original method, as well as
1931 what arguments to pass if it does so.
1933 The return value of the modifier is what will be seen by the caller.
1937 =head2 Introspection
1941 =item B<< Class::MOP::Class->meta >>
1943 This will return a L<Class::MOP::Class> instance for this class.
1945 It should also be noted that L<Class::MOP> will actually bootstrap
1946 this module by installing a number of attribute meta-objects into its
1953 Stevan Little E<lt>stevan@iinteractive.comE<gt>
1955 =head1 COPYRIGHT AND LICENSE
1957 Copyright 2006-2009 by Infinity Interactive, Inc.
1959 L<http://www.iinteractive.com>
1961 This library is free software; you can redistribute it and/or modify
1962 it under the same terms as Perl itself.