2 package Class::MOP::Class;
7 use Class::MOP::Instance;
8 use Class::MOP::Method::Wrapped;
9 use Class::MOP::Method::Accessor;
10 use Class::MOP::Method::Constructor;
13 use Scalar::Util 'blessed', 'weaken';
14 use Sub::Name 'subname';
15 use Devel::GlobalDestruction 'in_global_destruction';
17 our $VERSION = '0.89';
18 $VERSION = eval $VERSION;
19 our $AUTHORITY = 'cpan:STEVAN';
21 use base 'Class::MOP::Module';
31 $package_name = shift;
34 $package_name = $options{package};
37 (defined $package_name && $package_name && !ref($package_name))
38 || confess "You must pass a package name and it cannot be blessed";
40 return Class::MOP::get_metaclass_by_name($package_name)
41 || $class->_construct_class_instance(package => $package_name, @_);
44 sub construct_class_instance {
45 Carp::cluck('The construct_class_instance method has been made private.'
46 . " The public version is deprecated and will be removed in a future release.\n");
47 shift->_construct_class_instance(@_);
50 # NOTE: (meta-circularity)
51 # this is a special form of _construct_instance
52 # (see below), which is used to construct class
53 # meta-object instances for any Class::MOP::*
54 # class. All other classes will use the more
55 # normal &construct_instance.
56 sub _construct_class_instance {
58 my $options = @_ == 1 ? $_[0] : {@_};
59 my $package_name = $options->{package};
60 (defined $package_name && $package_name)
61 || confess "You must pass a package name";
63 # return the metaclass if we have it cached,
64 # and it is still defined (it has not been
65 # reaped by DESTROY yet, which can happen
66 # annoyingly enough during global destruction)
68 if (defined(my $meta = Class::MOP::get_metaclass_by_name($package_name))) {
73 # we need to deal with the possibility
74 # of class immutability here, and then
75 # get the name of the class appropriately
77 ? ($class->is_immutable
78 ? $class->get_mutable_metaclass_name()
82 # now create the metaclass
84 if ($class eq 'Class::MOP::Class') {
85 $meta = $class->_new($options);
89 # it is safe to use meta here because
90 # class will always be a subclass of
91 # Class::MOP::Class, which defines meta
92 $meta = $class->meta->_construct_instance($options)
95 # and check the metaclass compatibility
96 $meta->_check_metaclass_compatibility();
98 Class::MOP::store_metaclass_by_name($package_name, $meta);
101 # we need to weaken any anon classes
102 # so that they can call DESTROY properly
103 Class::MOP::weaken_metaclass($package_name) if $meta->is_anon_class;
110 my $options = @_ == 1 ? $_[0] : {@_};
113 # inherited from Class::MOP::Package
114 'package' => $options->{package},
117 # since the following attributes will
118 # actually be loaded from the symbol
119 # table, and actually bypass the instance
120 # entirely, we can just leave these things
121 # listed here for reference, because they
122 # should not actually have a value associated
124 'namespace' => \undef,
126 # inherited from Class::MOP::Module
128 'authority' => \undef,
130 # defined in Class::MOP::Class
131 'superclasses' => \undef,
135 'attribute_metaclass' =>
136 ( $options->{'attribute_metaclass'} || 'Class::MOP::Attribute' ),
137 'method_metaclass' =>
138 ( $options->{'method_metaclass'} || 'Class::MOP::Method' ),
139 'wrapped_method_metaclass' => (
140 $options->{'wrapped_method_metaclass'}
141 || 'Class::MOP::Method::Wrapped'
143 'instance_metaclass' =>
144 ( $options->{'instance_metaclass'} || 'Class::MOP::Instance' ),
145 'immutable_trait' => (
146 $options->{'immutable_trait'}
147 || 'Class::MOP::Class::Immutable::Trait'
149 'constructor_name' => ( $options->{constructor_name} || 'new' ),
150 'constructor_class' => (
151 $options->{constructor_class} || 'Class::MOP::Method::Constructor'
153 'destructor_class' => $options->{destructor_class},
157 sub reset_package_cache_flag { (shift)->{'_package_cache_flag'} = undef }
158 sub update_package_cache_flag {
161 # we can manually update the cache number
162 # since we are actually adding the method
163 # to our cache as well. This avoids us
164 # having to regenerate the method_map.
166 $self->{'_package_cache_flag'} = Class::MOP::check_package_cache_flag($self->name);
170 sub check_metaclass_compatibility {
171 Carp::cluck('The check_metaclass_compatibility method has been made private.'
172 . " The public version is deprecated and will be removed in a future release.\n");
173 shift->_check_metaclass_compatibility(@_);
176 sub _check_metaclass_compatibility {
179 # this is always okay ...
180 return if ref($self) eq 'Class::MOP::Class' &&
181 $self->instance_metaclass eq 'Class::MOP::Instance';
183 my @class_list = $self->linearized_isa;
184 shift @class_list; # shift off $self->name
186 foreach my $superclass_name (@class_list) {
187 my $super_meta = Class::MOP::get_metaclass_by_name($superclass_name) || next;
190 # we need to deal with the possibility
191 # of class immutability here, and then
192 # get the name of the class appropriately
194 = $super_meta->is_immutable
195 ? $super_meta->get_mutable_metaclass_name()
198 ($self->isa($super_meta_type))
199 || confess "The metaclass of " . $self->name . " ("
200 . (ref($self)) . ")" . " is not compatible with the " .
201 "metaclass of its superclass, ".$superclass_name . " ("
202 . ($super_meta_type) . ")";
204 # we also need to check that instance metaclasses
205 # are compatibile in the same the class.
206 ($self->instance_metaclass->isa($super_meta->instance_metaclass))
207 || confess "The instance metaclass for " . $self->name . " (" . ($self->instance_metaclass) . ")" .
208 " is not compatible with the " .
209 "instance metaclass of its superclass, " . $superclass_name . " (" . ($super_meta->instance_metaclass) . ")";
217 # this should be sufficient, if you have a
218 # use case where it is not, write a test and
220 my $ANON_CLASS_SERIAL = 0;
223 # we need a sufficiently annoying prefix
224 # this should suffice for now, this is
225 # used in a couple of places below, so
226 # need to put it up here for now.
227 my $ANON_CLASS_PREFIX = 'Class::MOP::Class::__ANON__::SERIAL::';
231 no warnings 'uninitialized';
232 $self->name =~ /^$ANON_CLASS_PREFIX/;
235 sub create_anon_class {
236 my ($class, %options) = @_;
237 my $package_name = $ANON_CLASS_PREFIX . ++$ANON_CLASS_SERIAL;
238 return $class->create($package_name, %options);
242 # this will only get called for
243 # anon-classes, all other calls
244 # are assumed to occur during
245 # global destruction and so don't
246 # really need to be handled explicitly
250 return if in_global_destruction(); # it'll happen soon anyway and this just makes things more complicated
252 no warnings 'uninitialized';
253 my $name = $self->name;
254 return unless $name =~ /^$ANON_CLASS_PREFIX/;
255 # Moose does a weird thing where it replaces the metaclass for
256 # class when fixing metaclass incompatibility. In that case,
257 # we don't want to clean out the namespace now. We can detect
258 # that because Moose will explicitly update the singleton
259 # cache in Class::MOP.
260 my $current_meta = Class::MOP::get_metaclass_by_name($name);
261 return if $current_meta ne $self;
263 my ($serial_id) = ($name =~ /^$ANON_CLASS_PREFIX(\d+)/);
265 @{$name . '::ISA'} = ();
266 %{$name . '::'} = ();
267 delete ${$ANON_CLASS_PREFIX}{$serial_id . '::'};
269 Class::MOP::remove_metaclass_by_name($name);
274 # creating classes with MOP ...
277 my ( $class, @args ) = @_;
279 unshift @args, 'package' if @args % 2 == 1;
281 my (%options) = @args;
282 my $package_name = $options{package};
284 (ref $options{superclasses} eq 'ARRAY')
285 || confess "You must pass an ARRAY ref of superclasses"
286 if exists $options{superclasses};
288 (ref $options{attributes} eq 'ARRAY')
289 || confess "You must pass an ARRAY ref of attributes"
290 if exists $options{attributes};
292 (ref $options{methods} eq 'HASH')
293 || confess "You must pass a HASH ref of methods"
294 if exists $options{methods};
296 my (%initialize_options) = @args;
297 delete @initialize_options{qw(
305 my $meta = $class->initialize( $package_name => %initialize_options );
307 $meta->_instantiate_module( $options{version}, $options{authority} );
310 $meta->add_method('meta' => sub {
311 $class->initialize(ref($_[0]) || $_[0]);
314 $meta->superclasses(@{$options{superclasses}})
315 if exists $options{superclasses};
317 # process attributes first, so that they can
318 # install accessors, but locally defined methods
319 # can then overwrite them. It is maybe a little odd, but
320 # I think this should be the order of things.
321 if (exists $options{attributes}) {
322 foreach my $attr (@{$options{attributes}}) {
323 $meta->add_attribute($attr);
326 if (exists $options{methods}) {
327 foreach my $method_name (keys %{$options{methods}}) {
328 $meta->add_method($method_name, $options{methods}->{$method_name});
337 # all these attribute readers will be bootstrapped
338 # away in the Class::MOP bootstrap section
340 sub get_attribute_map { $_[0]->{'attributes'} }
341 sub attribute_metaclass { $_[0]->{'attribute_metaclass'} }
342 sub method_metaclass { $_[0]->{'method_metaclass'} }
343 sub wrapped_method_metaclass { $_[0]->{'wrapped_method_metaclass'} }
344 sub instance_metaclass { $_[0]->{'instance_metaclass'} }
345 sub immutable_trait { $_[0]->{'immutable_trait'} }
346 sub constructor_class { $_[0]->{'constructor_class'} }
347 sub constructor_name { $_[0]->{'constructor_name'} }
348 sub destructor_class { $_[0]->{'destructor_class'} }
350 # Instance Construction & Cloning
356 # we need to protect the integrity of the
357 # Class::MOP::Class singletons here, so we
358 # delegate this to &construct_class_instance
359 # which will deal with the singletons
360 return $class->_construct_class_instance(@_)
361 if $class->name->isa('Class::MOP::Class');
362 return $class->_construct_instance(@_);
365 sub construct_instance {
366 Carp::cluck('The construct_instance method has been made private.'
367 . " The public version is deprecated and will be removed in a future release.\n");
368 shift->_construct_instance(@_);
371 sub _construct_instance {
373 my $params = @_ == 1 ? $_[0] : {@_};
374 my $meta_instance = $class->get_meta_instance();
376 # the code below is almost certainly incorrect
377 # but this is foreign inheritance, so we might
378 # have to kludge it in the end.
379 my $instance = $params->{__INSTANCE__} || $meta_instance->create_instance();
380 foreach my $attr ($class->get_all_attributes()) {
381 $attr->initialize_instance_slot($meta_instance, $instance, $params);
384 # this will only work for a HASH instance type
385 if ($class->is_anon_class) {
386 (Scalar::Util::reftype($instance) eq 'HASH')
387 || confess "Currently only HASH based instances are supported with instance of anon-classes";
389 # At some point we should make this official
390 # as a reserved slot name, but right now I am
391 # going to keep it here.
392 # my $RESERVED_MOP_SLOT = '__MOP__';
393 $instance->{'__MOP__'} = $class;
399 sub get_meta_instance {
401 $self->{'_meta_instance'} ||= $self->_create_meta_instance();
404 sub create_meta_instance {
405 Carp::cluck('The create_meta_instance method has been made private.'
406 . " The public version is deprecated and will be removed in a future release.\n");
407 shift->_create_meta_instance(@_);
410 sub _create_meta_instance {
413 my $instance = $self->instance_metaclass->new(
414 associated_metaclass => $self,
415 attributes => [ $self->get_all_attributes() ],
418 $self->add_meta_instance_dependencies()
419 if $instance->is_dependent_on_superclasses();
426 my $instance = shift;
427 (blessed($instance) && $instance->isa($class->name))
428 || confess "You must pass an instance of the metaclass (" . (ref $class ? $class->name : $class) . "), not ($instance)";
431 # we need to protect the integrity of the
432 # Class::MOP::Class singletons here, they
433 # should not be cloned.
434 return $instance if $instance->isa('Class::MOP::Class');
435 $class->_clone_instance($instance, @_);
439 Carp::cluck('The clone_instance method has been made private.'
440 . " The public version is deprecated and will be removed in a future release.\n");
441 shift->_clone_instance(@_);
444 sub _clone_instance {
445 my ($class, $instance, %params) = @_;
447 || confess "You can only clone instances, ($instance) is not a blessed instance";
448 my $meta_instance = $class->get_meta_instance();
449 my $clone = $meta_instance->clone_instance($instance);
450 foreach my $attr ($class->get_all_attributes()) {
451 if ( defined( my $init_arg = $attr->init_arg ) ) {
452 if (exists $params{$init_arg}) {
453 $attr->set_value($clone, $params{$init_arg});
460 sub rebless_instance {
461 my ($self, $instance, %params) = @_;
463 my $old_metaclass = Class::MOP::class_of($instance);
465 my $old_class = $old_metaclass ? $old_metaclass->name : blessed($instance);
466 $self->name->isa($old_class)
467 || confess "You may rebless only into a subclass of ($old_class), of which (". $self->name .") isn't.";
469 $old_metaclass->rebless_instance_away($instance, $self, %params)
472 my $meta_instance = $self->get_meta_instance();
475 # we use $_[1] here because of t/306_rebless_overload.t regressions on 5.8.8
476 $meta_instance->rebless_instance_structure($_[1], $self);
478 foreach my $attr ( $self->get_all_attributes ) {
479 if ( $attr->has_value($instance) ) {
480 if ( defined( my $init_arg = $attr->init_arg ) ) {
481 $params{$init_arg} = $attr->get_value($instance)
482 unless exists $params{$init_arg};
485 $attr->set_value($instance, $attr->get_value($instance));
490 foreach my $attr ($self->get_all_attributes) {
491 $attr->initialize_instance_slot($meta_instance, $instance, \%params);
497 sub rebless_instance_away {
498 # this intentionally does nothing, it is just a hook
505 my $var_spec = { sigil => '@', type => 'ARRAY', name => 'ISA' };
508 @{$self->get_package_symbol($var_spec)} = @supers;
511 # on 5.8 and below, we need to call
512 # a method to get Perl to detect
513 # a cycle in the class hierarchy
514 my $class = $self->name;
518 # we need to check the metaclass
519 # compatibility here so that we can
520 # be sure that the superclass is
521 # not potentially creating an issues
522 # we don't know about
524 $self->_check_metaclass_compatibility();
525 $self->_superclasses_updated();
527 @{$self->get_package_symbol($var_spec)};
530 sub _superclasses_updated {
532 $self->update_meta_instance_dependencies();
537 my $super_class = $self->name;
539 return @{ $super_class->mro::get_isarev() };
542 sub direct_subclasses {
544 my $super_class = $self->name;
549 } Class::MOP::Class->initialize($_)->superclasses
554 return @{ mro::get_linear_isa( (shift)->name ) };
557 sub class_precedence_list {
559 my $name = $self->name;
561 unless (Class::MOP::IS_RUNNING_ON_5_10()) {
563 # We need to check for circular inheritance here
564 # if we are are not on 5.10, cause 5.8 detects it
565 # late. This will do nothing if all is well, and
566 # blow up otherwise. Yes, it's an ugly hack, better
567 # suggestions are welcome.
569 ($name || return)->isa('This is a test for circular inheritance')
572 # if our mro is c3, we can
573 # just grab the linear_isa
574 if (mro::get_mro($name) eq 'c3') {
575 return @{ mro::get_linear_isa($name) }
579 # we can't grab the linear_isa for dfs
580 # since it has all the duplicates
585 $self->initialize($_)->class_precedence_list()
586 } $self->superclasses()
593 sub wrap_method_body {
594 my ( $self, %args ) = @_;
596 ('CODE' eq ref $args{body})
597 || confess "Your code block must be a CODE reference";
599 $self->method_metaclass->wrap(
600 package_name => $self->name,
606 my ($self, $method_name, $method) = @_;
607 (defined $method_name && $method_name)
608 || confess "You must define a method name";
611 if (blessed($method)) {
612 $body = $method->body;
613 if ($method->package_name ne $self->name) {
614 $method = $method->clone(
615 package_name => $self->name,
617 ) if $method->can('clone');
622 $method = $self->wrap_method_body( body => $body, name => $method_name );
625 $method->attach_to_class($self);
627 $self->get_method_map->{$method_name} = $method;
629 my ( $current_package, $current_name ) = Class::MOP::get_code_info($body);
631 if ( !defined $current_name || $current_name eq '__ANON__' ) {
632 my $full_method_name = ($self->name . '::' . $method_name);
633 subname($full_method_name => $body);
636 $self->add_package_symbol(
637 { sigil => '&', type => 'CODE', name => $method_name },
643 my $fetch_and_prepare_method = sub {
644 my ($self, $method_name) = @_;
645 my $wrapped_metaclass = $self->wrapped_method_metaclass;
647 my $method = $self->get_method($method_name);
648 # if we dont have local ...
650 # try to find the next method
651 $method = $self->find_next_method_by_name($method_name);
652 # die if it does not exist
654 || confess "The method '$method_name' was not found in the inheritance hierarchy for " . $self->name;
655 # and now make sure to wrap it
656 # even if it is already wrapped
657 # because we need a new sub ref
658 $method = $wrapped_metaclass->wrap($method);
661 # now make sure we wrap it properly
662 $method = $wrapped_metaclass->wrap($method)
663 unless $method->isa($wrapped_metaclass);
665 $self->add_method($method_name => $method);
670 sub add_before_method_modifier {
671 my ($self, $method_name, $method_modifier) = @_;
672 (defined $method_name && $method_name)
673 || confess "You must pass in a method name";
674 my $method = $fetch_and_prepare_method->($self, $method_name);
675 $method->add_before_modifier(
676 subname(':before-' . $counter++ . q{-} . $method_name => $method_modifier)
680 sub add_after_method_modifier {
681 my ($self, $method_name, $method_modifier) = @_;
682 (defined $method_name && $method_name)
683 || confess "You must pass in a method name";
684 my $method = $fetch_and_prepare_method->($self, $method_name);
685 $method->add_after_modifier(
686 subname(':after-' . $counter++ . q{-} . $method_name => $method_modifier)
690 sub add_around_method_modifier {
691 my ($self, $method_name, $method_modifier) = @_;
692 (defined $method_name && $method_name)
693 || confess "You must pass in a method name";
694 my $method = $fetch_and_prepare_method->($self, $method_name);
695 $method->add_around_modifier(
696 subname(':around-' . $counter++ . q{-} . $method_name => $method_modifier)
701 # the methods above used to be named like this:
702 # ${pkg}::${method}:(before|after|around)
703 # but this proved problematic when using one modifier
704 # to wrap multiple methods (something which is likely
705 # to happen pretty regularly IMO). So instead of naming
706 # it like this, I have chosen to just name them purely
707 # with their modifier names, like so:
708 # :(before|after|around)
709 # The fact is that in a stack trace, it will be fairly
710 # evident from the context what method they are attached
711 # to, and so don't need the fully qualified name.
715 Carp::cluck("The alias_method method is deprecated. Use add_method instead.\n");
717 shift->add_method(@_);
721 my ($self, $method_name) = @_;
722 (defined $method_name && $method_name)
723 || confess "You must define a method name";
725 exists $self->get_method_map->{$method_name};
729 my ($self, $method_name) = @_;
730 (defined $method_name && $method_name)
731 || confess "You must define a method name";
733 return $self->get_method_map->{$method_name};
737 my ($self, $method_name) = @_;
738 (defined $method_name && $method_name)
739 || confess "You must define a method name";
741 my $removed_method = delete $self->get_method_map->{$method_name};
743 $self->remove_package_symbol(
744 { sigil => '&', type => 'CODE', name => $method_name }
747 $removed_method->detach_from_class if $removed_method;
749 $self->update_package_cache_flag; # still valid, since we just removed the method from the map
751 return $removed_method;
754 sub get_method_list {
756 keys %{$self->get_method_map};
759 sub find_method_by_name {
760 my ($self, $method_name) = @_;
761 (defined $method_name && $method_name)
762 || confess "You must define a method name to find";
763 foreach my $class ($self->linearized_isa) {
764 # fetch the meta-class ...
765 my $meta = $self->initialize($class);
766 return $meta->get_method($method_name)
767 if $meta->has_method($method_name);
772 sub get_all_methods {
774 my %methods = map { %{ $self->initialize($_)->get_method_map } } reverse $self->linearized_isa;
775 return values %methods;
778 sub compute_all_applicable_methods {
779 Carp::cluck('The compute_all_applicable_methods method is deprecated.'
780 . " Use get_all_methods instead.\n");
785 class => $_->package_name,
786 code => $_, # sigh, overloading
788 } shift->get_all_methods(@_);
791 sub get_all_method_names {
794 grep { $uniq{$_}++ == 0 } map { $_->name } $self->get_all_methods;
797 sub find_all_methods_by_name {
798 my ($self, $method_name) = @_;
799 (defined $method_name && $method_name)
800 || confess "You must define a method name to find";
802 foreach my $class ($self->linearized_isa) {
803 # fetch the meta-class ...
804 my $meta = $self->initialize($class);
806 name => $method_name,
808 code => $meta->get_method($method_name)
809 } if $meta->has_method($method_name);
814 sub find_next_method_by_name {
815 my ($self, $method_name) = @_;
816 (defined $method_name && $method_name)
817 || confess "You must define a method name to find";
818 my @cpl = $self->linearized_isa;
819 shift @cpl; # discard ourselves
820 foreach my $class (@cpl) {
821 # fetch the meta-class ...
822 my $meta = $self->initialize($class);
823 return $meta->get_method($method_name)
824 if $meta->has_method($method_name);
833 # either we have an attribute object already
834 # or we need to create one from the args provided
835 my $attribute = blessed($_[0]) ? $_[0] : $self->attribute_metaclass->new(@_);
836 # make sure it is derived from the correct type though
837 ($attribute->isa('Class::MOP::Attribute'))
838 || confess "Your attribute must be an instance of Class::MOP::Attribute (or a subclass)";
840 # first we attach our new attribute
841 # because it might need certain information
842 # about the class which it is attached to
843 $attribute->attach_to_class($self);
845 # then we remove attributes of a conflicting
846 # name here so that we can properly detach
847 # the old attr object, and remove any
848 # accessors it would have generated
849 if ( $self->has_attribute($attribute->name) ) {
850 $self->remove_attribute($attribute->name);
852 $self->invalidate_meta_instances();
855 # get our count of previously inserted attributes and
856 # increment by one so this attribute knows its order
857 my $order = (scalar keys %{$self->get_attribute_map}) - 1;
858 $attribute->_set_insertion_order($order + 1);
860 # then onto installing the new accessors
861 $self->get_attribute_map->{$attribute->name} = $attribute;
863 # invalidate package flag here
867 eval { $attribute->install_accessors() };
871 $self->remove_attribute($attribute->name);
878 sub update_meta_instance_dependencies {
881 if ( $self->{meta_instance_dependencies} ) {
882 return $self->add_meta_instance_dependencies;
886 sub add_meta_instance_dependencies {
889 $self->remove_meta_instance_dependencies;
891 my @attrs = $self->get_all_attributes();
894 my @classes = grep { not $seen{$_->name}++ } map { $_->associated_class } @attrs;
896 foreach my $class ( @classes ) {
897 $class->add_dependent_meta_instance($self);
900 $self->{meta_instance_dependencies} = \@classes;
903 sub remove_meta_instance_dependencies {
906 if ( my $classes = delete $self->{meta_instance_dependencies} ) {
907 foreach my $class ( @$classes ) {
908 $class->remove_dependent_meta_instance($self);
918 sub add_dependent_meta_instance {
919 my ( $self, $metaclass ) = @_;
920 push @{ $self->{dependent_meta_instances} }, $metaclass;
923 sub remove_dependent_meta_instance {
924 my ( $self, $metaclass ) = @_;
925 my $name = $metaclass->name;
926 @$_ = grep { $_->name ne $name } @$_ for $self->{dependent_meta_instances};
929 sub invalidate_meta_instances {
931 $_->invalidate_meta_instance() for $self, @{ $self->{dependent_meta_instances} };
934 sub invalidate_meta_instance {
936 undef $self->{_meta_instance};
940 my ($self, $attribute_name) = @_;
941 (defined $attribute_name && $attribute_name)
942 || confess "You must define an attribute name";
943 exists $self->get_attribute_map->{$attribute_name};
947 my ($self, $attribute_name) = @_;
948 (defined $attribute_name && $attribute_name)
949 || confess "You must define an attribute name";
950 return $self->get_attribute_map->{$attribute_name}
952 # this will return undef anyway, so no need ...
953 # if $self->has_attribute($attribute_name);
957 sub remove_attribute {
958 my ($self, $attribute_name) = @_;
959 (defined $attribute_name && $attribute_name)
960 || confess "You must define an attribute name";
961 my $removed_attribute = $self->get_attribute_map->{$attribute_name};
962 return unless defined $removed_attribute;
963 delete $self->get_attribute_map->{$attribute_name};
964 $self->invalidate_meta_instances();
965 $removed_attribute->remove_accessors();
966 $removed_attribute->detach_from_class();
967 return $removed_attribute;
970 sub get_attribute_list {
972 keys %{$self->get_attribute_map};
975 sub get_all_attributes {
977 my %attrs = map { %{ $self->initialize($_)->get_attribute_map } } reverse $self->linearized_isa;
978 return values %attrs;
981 sub compute_all_applicable_attributes {
982 Carp::cluck('The compute_all_applicable_attributes method has been deprecated.'
983 . " Use get_all_attributes instead.\n");
985 shift->get_all_attributes(@_);
988 sub find_attribute_by_name {
989 my ($self, $attr_name) = @_;
990 foreach my $class ($self->linearized_isa) {
991 # fetch the meta-class ...
992 my $meta = $self->initialize($class);
993 return $meta->get_attribute($attr_name)
994 if $meta->has_attribute($attr_name);
999 # check if we can reinitialize
1003 # if any local attr is defined
1004 return if $self->get_attribute_list;
1006 # or any non-declared methods
1007 if ( my @methods = values %{ $self->get_method_map } ) {
1008 my $metaclass = $self->method_metaclass;
1009 foreach my $method ( @methods ) {
1010 return if $method->isa("Class::MOP::Method::Generated");
1011 # FIXME do we need to enforce this too? return unless $method->isa($metaclass);
1020 sub is_mutable { 1 }
1021 sub is_immutable { 0 }
1023 sub _immutable_options {
1024 my ( $self, @args ) = @_;
1027 inline_accessors => 1,
1028 inline_constructor => 1,
1029 inline_destructor => 0,
1031 immutable_trait => $self->immutable_trait,
1032 constructor_name => $self->constructor_name,
1033 constructor_class => $self->constructor_class,
1034 destructor_class => $self->destructor_class,
1039 sub make_immutable {
1040 my ( $self, @args ) = @_;
1042 if ( $self->is_mutable ) {
1043 $self->_initialize_immutable( $self->_immutable_options(@args) );
1044 $self->_rebless_as_immutable(@args);
1055 if ( $self->is_immutable ) {
1056 my @args = $self->immutable_options;
1057 $self->_rebless_as_mutable();
1058 $self->_remove_inlined_code(@args);
1059 delete $self->{__immutable};
1067 sub _rebless_as_immutable {
1068 my ( $self, @args ) = @_;
1070 $self->{__immutable}{original_class} = ref $self;
1072 bless $self => $self->_immutable_metaclass(@args);
1075 sub _immutable_metaclass {
1076 my ( $self, %args ) = @_;
1078 if ( my $class = $args{immutable_metaclass} ) {
1082 my $trait = $args{immutable_trait} = $self->immutable_trait
1083 || confess "no immutable trait specified for $self";
1085 my $meta_attr = $self->meta->find_attribute_by_name("immutable_trait");
1089 if ( $meta_attr and $trait eq $meta_attr->default ) {
1090 # if the trait is the same as the default we try and pick a
1091 # predictable name for the immutable metaclass
1092 $class_name = 'Class::MOP::Class::Immutable::' . ref($self);
1095 $class_name = join '::', 'Class::MOP::Class::Immutable::CustomTrait',
1096 $trait, 'ForMetaClass', ref($self);
1100 if Class::MOP::is_class_loaded($class_name);
1102 # If the metaclass is a subclass of CMOP::Class which has had
1103 # metaclass roles applied (via Moose), then we want to make sure
1104 # that we preserve that anonymous class (see Fey::ORM for an
1105 # example of where this matters).
1107 = $self->meta->is_immutable
1108 ? $self->meta->get_mutable_metaclass_name
1111 my $meta = $meta_name->create(
1113 superclasses => [ ref $self ],
1116 Class::MOP::load_class($trait);
1117 for my $meth ( Class::MOP::Class->initialize($trait)->get_all_methods ) {
1118 next if $meta->has_method( $meth->name );
1120 if ( $meta->find_method_by_name( $meth->name ) ) {
1121 $meta->add_around_method_modifier( $meth->name, $meth->body );
1124 $meta->add_method( $meth->name, $meth->clone );
1128 $meta->make_immutable( inline_constructor => 0 );
1133 sub _remove_inlined_code {
1136 $self->remove_method( $_->name ) for $self->_inlined_methods;
1138 delete $self->{__immutable}{inlined_methods};
1141 sub _inlined_methods { @{ $_[0]{__immutable}{inlined_methods} || [] } }
1143 sub _add_inlined_method {
1144 my ( $self, $method ) = @_;
1146 push @{ $self->{__immutable}{inlined_methods} ||= [] }, $method;
1149 sub _initialize_immutable {
1150 my ( $self, %args ) = @_;
1152 $self->{__immutable}{options} = \%args;
1153 $self->_install_inlined_code(%args);
1156 sub _install_inlined_code {
1157 my ( $self, %args ) = @_;
1160 $self->_inline_accessors(%args) if $args{inline_accessors};
1161 $self->_inline_constructor(%args) if $args{inline_constructor};
1162 $self->_inline_destructor(%args) if $args{inline_destructor};
1165 sub _rebless_as_mutable {
1168 bless $self, $self->get_mutable_metaclass_name;
1173 sub _inline_accessors {
1176 foreach my $attr_name ( $self->get_attribute_list ) {
1177 $self->get_attribute($attr_name)->install_accessors(1);
1181 sub _inline_constructor {
1182 my ( $self, %args ) = @_;
1184 my $name = $args{constructor_name};
1186 if ( $self->has_method($name) && !$args{replace_constructor} ) {
1187 my $class = $self->name;
1188 warn "Not inlining a constructor for $class since it defines"
1189 . " its own constructor.\n"
1190 . "If you are certain you don't need to inline your"
1191 . " constructor, specify inline_constructor => 0 in your"
1192 . " call to $class->meta->make_immutable\n";
1196 my $constructor_class = $args{constructor_class};
1198 Class::MOP::load_class($constructor_class);
1200 my $constructor = $constructor_class->new(
1204 package_name => $self->name,
1208 if ( $args{replace_constructor} or $constructor->can_be_inlined ) {
1209 $self->add_method( $name => $constructor );
1210 $self->_add_inlined_method($constructor);
1214 sub _inline_destructor {
1215 my ( $self, %args ) = @_;
1217 ( exists $args{destructor_class} && defined $args{destructor_class} )
1218 || confess "The 'inline_destructor' option is present, but "
1219 . "no destructor class was specified";
1221 if ( $self->has_method('DESTROY') && ! $args{replace_destructor} ) {
1222 my $class = $self->name;
1223 warn "Not inlining a destructor for $class since it defines"
1224 . " its own destructor.\n";
1228 my $destructor_class = $args{destructor_class};
1230 Class::MOP::load_class($destructor_class);
1232 return unless $destructor_class->is_needed($self);
1234 my $destructor = $destructor_class->new(
1237 package_name => $self->name,
1241 if ( $args{replace_destructor} or $destructor->can_be_inlined ) {
1242 $self->add_method( 'DESTROY' => $destructor );
1243 $self->_add_inlined_method($destructor);
1255 Class::MOP::Class - Class Meta Object
1259 # assuming that class Foo
1260 # has been defined, you can
1262 # use this for introspection ...
1264 # add a method to Foo ...
1265 Foo->meta->add_method( 'bar' => sub {...} )
1267 # get a list of all the classes searched
1268 # the method dispatcher in the correct order
1269 Foo->meta->class_precedence_list()
1271 # remove a method from Foo
1272 Foo->meta->remove_method('bar');
1274 # or use this to actually create classes ...
1276 Class::MOP::Class->create(
1279 superclasses => ['Foo'],
1281 Class::MOP::Attribute->new('$bar'),
1282 Class::MOP::Attribute->new('$baz'),
1285 calculate_bar => sub {...},
1286 construct_baz => sub {...}
1293 The Class Protocol is the largest and most complex part of the
1294 Class::MOP meta-object protocol. It controls the introspection and
1295 manipulation of Perl 5 classes, and it can create them as well. The
1296 best way to understand what this module can do, is to read the
1297 documentation for each of its methods.
1301 C<Class::MOP::Class> is a subclass of L<Class::MOP::Module>.
1305 =head2 Class construction
1307 These methods all create new C<Class::MOP::Class> objects. These
1308 objects can represent existing classes, or they can be used to create
1309 new classes from scratch.
1311 The metaclass object for a given class is a singleton. If you attempt
1312 to create a metaclass for the same class twice, you will just get the
1317 =item B<< Class::MOP::Class->create($package_name, %options) >>
1319 This method creates a new C<Class::MOP::Class> object with the given
1320 package name. It accepts a number of options.
1326 An optional version number for the newly created package.
1330 An optional authority for the newly created package.
1332 =item * superclasses
1334 An optional array reference of superclass names.
1338 An optional hash reference of methods for the class. The keys of the
1339 hash reference are method names, and values are subroutine references.
1343 An optional array reference of attributes.
1345 An attribute can be passed as an existing L<Class::MOP::Attribute>
1346 object, I<or> or as a hash reference of options which will be passed
1347 to the attribute metaclass's constructor.
1351 =item B<< Class::MOP::Class->create_anon_class(%options) >>
1353 This method works just like C<< Class::MOP::Class->create >> but it
1354 creates an "anonymous" class. In fact, the class does have a name, but
1355 that name is a unique name generated internally by this module.
1357 It accepts the same C<superclasses>, C<methods>, and C<attributes>
1358 parameters that C<create> accepts.
1360 Anonymous classes are destroyed once the metaclass they are attached
1361 to goes out of scope, and will be removed from Perl's internal symbol
1364 All instances of an anonymous class keep a special reference to the
1365 metaclass object, which prevents the metaclass from going out of scope
1366 while any instances exist.
1368 This only works if the instance if based on a hash reference, however.
1370 =item B<< Class::MOP::Class->initialize($package_name, %options) >>
1372 This method will initialize a C<Class::MOP::Class> object for the
1373 named package. Unlike C<create>, this method I<will not> create a new
1376 The purpose of this method is to retrieve a C<Class::MOP::Class>
1377 object for introspecting an existing class.
1379 If an existing C<Class::MOP::Class> object exists for the named
1380 package, it will be returned, and any options provided will be
1383 If the object does not yet exist, it will be created.
1385 The valid options that can be passed to this method are
1386 C<attribute_metaclass>, C<method_metaclass>,
1387 C<wrapped_method_metaclass>, and C<instance_metaclass>. These are all
1388 optional, and default to the appropriate class in the C<Class::MOP>
1393 =head2 Object instance construction and cloning
1395 These methods are all related to creating and/or cloning object
1400 =item B<< $metaclass->clone_object($instance, %params) >>
1402 This method clones an existing object instance. Any parameters you
1403 provide are will override existing attribute values in the object.
1405 This is a convenience method for cloning an object instance, then
1406 blessing it into the appropriate package.
1408 You could implement a clone method in your class, using this method:
1411 my ($self, %params) = @_;
1412 $self->meta->clone_object($self, %params);
1415 =item B<< $metaclass->rebless_instance($instance, %params) >>
1417 This method changes the class of C<$instance> to the metaclass's class.
1419 You can only rebless an instance into a subclass of its current
1420 class. If you pass any additional parameters, these will be treated
1421 like constructor parameters and used to initialize the object's
1422 attributes. Any existing attributes that are already set will be
1425 Before reblessing the instance, this method will call
1426 C<rebless_instance_away> on the instance's current metaclass. This method
1427 will be passed the instance, the new metaclass, and any parameters
1428 specified to C<rebless_instance>. By default, C<rebless_instance_away>
1429 does nothing; it is merely a hook.
1431 =item B<< $metaclass->new_object(%params) >>
1433 This method is used to create a new object of the metaclass's
1434 class. Any parameters you provide are used to initialize the
1435 instance's attributes. A special C<__INSTANCE__> key can be passed to
1436 provide an already generated instance, rather than having Class::MOP
1437 generate it for you. This is mostly useful for using Class::MOP with
1438 foreign classes, which generally generate instances using their own
1441 =item B<< $metaclass->instance_metaclass >>
1443 Returns the class name of the instance metaclass, see
1444 L<Class::MOP::Instance> for more information on the instance
1447 =item B<< $metaclass->get_meta_instance >>
1449 Returns an instance of the C<instance_metaclass> to be used in the
1450 construction of a new instance of the class.
1454 =head2 Informational predicates
1456 These are a few predicate methods for asking information about the
1461 =item B<< $metaclass->is_anon_class >>
1463 This returns true if the class was created by calling C<<
1464 Class::MOP::Class->create_anon_class >>.
1466 =item B<< $metaclass->is_mutable >>
1468 This returns true if the class is still mutable.
1470 =item B<< $metaclass->is_immutable >>
1472 This returns true if the class has been made immutable.
1474 =item B<< $metaclass->is_pristine >>
1476 A class is I<not> pristine if it has non-inherited attributes or if it
1477 has any generated methods.
1481 =head2 Inheritance Relationships
1485 =item B<< $metaclass->superclasses(@superclasses) >>
1487 This is a read-write accessor which represents the superclass
1488 relationships of the metaclass's class.
1490 This is basically sugar around getting and setting C<@ISA>.
1492 =item B<< $metaclass->class_precedence_list >>
1494 This returns a list of all of the class's ancestor classes. The
1495 classes are returned in method dispatch order.
1497 =item B<< $metaclass->linearized_isa >>
1499 This returns a list based on C<class_precedence_list> but with all
1502 =item B<< $metaclass->subclasses >>
1504 This returns a list of all subclasses for this class, even indirect
1507 =item B<< $metaclass->direct_subclasses >>
1509 This returns a list of immediate subclasses for this class, which does not
1510 include indirect subclasses.
1514 =head2 Method introspection and creation
1516 These methods allow you to introspect a class's methods, as well as
1517 add, remove, or change methods.
1519 Determining what is truly a method in a Perl 5 class requires some
1520 heuristics (aka guessing).
1522 Methods defined outside the package with a fully qualified name (C<sub
1523 Package::name { ... }>) will be included. Similarly, methods named
1524 with a fully qualified name using L<Sub::Name> are also included.
1526 However, we attempt to ignore imported functions.
1528 Ultimately, we are using heuristics to determine what truly is a
1529 method in a class, and these heuristics may get the wrong answer in
1530 some edge cases. However, for most "normal" cases the heuristics work
1535 =item B<< $metaclass->get_method($method_name) >>
1537 This will return a L<Class::MOP::Method> for the specified
1538 C<$method_name>. If the class does not have the specified method, it
1541 =item B<< $metaclass->has_method($method_name) >>
1543 Returns a boolean indicating whether or not the class defines the
1544 named method. It does not include methods inherited from parent
1547 =item B<< $metaclass->get_method_map >>
1549 Returns a hash reference representing the methods defined in this
1550 class. The keys are method names and the values are
1551 L<Class::MOP::Method> objects.
1553 =item B<< $metaclass->get_method_list >>
1555 This will return a list of method I<names> for all methods defined in
1558 =item B<< $metaclass->get_all_methods >>
1560 This will traverse the inheritance hierarchy and return a list of all
1561 the L<Class::MOP::Method> objects for this class and its parents.
1563 =item B<< $metaclass->find_method_by_name($method_name) >>
1565 This will return a L<Class::MOP::Method> for the specified
1566 C<$method_name>. If the class does not have the specified method, it
1569 Unlike C<get_method>, this method I<will> look for the named method in
1572 =item B<< $metaclass->get_all_method_names >>
1574 This will return a list of method I<names> for all of this class's
1575 methods, including inherited methods.
1577 =item B<< $metaclass->find_all_methods_by_name($method_name) >>
1579 This method looks for the named method in the class and all of its
1580 parents. It returns every matching method it finds in the inheritance
1581 tree, so it returns a list of methods.
1583 Each method is returned as a hash reference with three keys. The keys
1584 are C<name>, C<class>, and C<code>. The C<code> key has a
1585 L<Class::MOP::Method> object as its value.
1587 The list of methods is distinct.
1589 =item B<< $metaclass->find_next_method_by_name($method_name) >>
1591 This method returns the first method in any superclass matching the
1592 given name. It is effectively the method that C<SUPER::$method_name>
1595 =item B<< $metaclass->add_method($method_name, $method) >>
1597 This method takes a method name and a subroutine reference, and adds
1598 the method to the class.
1600 The subroutine reference can be a L<Class::MOP::Method>, and you are
1601 strongly encouraged to pass a meta method object instead of a code
1602 reference. If you do so, that object gets stored as part of the
1603 class's method map directly. If not, the meta information will have to
1604 be recreated later, and may be incorrect.
1606 If you provide a method object, this method will clone that object if
1607 the object's package name does not match the class name. This lets us
1608 track the original source of any methods added from other classes
1609 (notably Moose roles).
1611 =item B<< $metaclass->remove_method($method_name) >>
1613 Remove the named method from the class. This method returns the
1614 L<Class::MOP::Method> object for the method.
1616 =item B<< $metaclass->method_metaclass >>
1618 Returns the class name of the method metaclass, see
1619 L<Class::MOP::Method> for more information on the method metaclass.
1621 =item B<< $metaclass->wrapped_method_metaclass >>
1623 Returns the class name of the wrapped method metaclass, see
1624 L<Class::MOP::Method::Wrapped> for more information on the wrapped
1629 =head2 Attribute introspection and creation
1631 Because Perl 5 does not have a core concept of attributes in classes,
1632 we can only return information about attributes which have been added
1633 via this class's methods. We cannot discover information about
1634 attributes which are defined in terms of "regular" Perl 5 methods.
1638 =item B<< $metaclass->get_attribute($attribute_name) >>
1640 This will return a L<Class::MOP::Attribute> for the specified
1641 C<$attribute_name>. If the class does not have the specified
1642 attribute, it returns C<undef>.
1644 NOTE that get_attribute does not search superclasses, for that you
1645 need to use C<find_attribute_by_name>.
1647 =item B<< $metaclass->has_attribute($attribute_name) >>
1649 Returns a boolean indicating whether or not the class defines the
1650 named attribute. It does not include attributes inherited from parent
1653 =item B<< $metaclass->get_attribute_map >>
1655 Returns a hash reference representing the attributes defined in this
1656 class. The keys are attribute names and the values are
1657 L<Class::MOP::Attribute> objects.
1659 =item B<< $metaclass->get_attribute_list >>
1661 This will return a list of attributes I<names> for all attributes
1662 defined in this class.
1664 =item B<< $metaclass->get_all_attributes >>
1666 This will traverse the inheritance hierarchy and return a list of all
1667 the L<Class::MOP::Attribute> objects for this class and its parents.
1669 =item B<< $metaclass->find_attribute_by_name($attribute_name) >>
1671 This will return a L<Class::MOP::Attribute> for the specified
1672 C<$attribute_name>. If the class does not have the specified
1673 attribute, it returns C<undef>
1675 Unlike C<get_attribute>, this attribute I<will> look for the named
1676 attribute in superclasses.
1678 =item B<< $metaclass->add_attribute(...) >>
1680 This method accepts either an existing L<Class::MOP::Attribute>
1681 object, or parameters suitable for passing to that class's C<new>
1684 The attribute provided will be added to the class.
1686 Any accessor methods defined by the attribute will be added to the
1687 class when the attribute is added.
1689 If an attribute of the same name already exists, the old attribute
1690 will be removed first.
1692 =item B<< $metaclass->remove_attribute($attribute_name) >>
1694 This will remove the named attribute from the class, and
1695 L<Class::MOP::Attribute> object.
1697 Removing an attribute also removes any accessor methods defined by the
1700 However, note that removing an attribute will only affect I<future>
1701 object instances created for this class, not existing instances.
1703 =item B<< $metaclass->attribute_metaclass >>
1705 Returns the class name of the attribute metaclass for this class. By
1706 default, this is L<Class::MOP::Attribute>. for more information on
1710 =head2 Class Immutability
1712 Making a class immutable "freezes" the class definition. You can no
1713 longer call methods which alter the class, such as adding or removing
1714 methods or attributes.
1716 Making a class immutable lets us optimize the class by inlining some
1717 methods, and also allows us to optimize some methods on the metaclass
1720 After immutabilization, the metaclass object will cache most
1721 informational methods such as C<get_method_map> and
1722 C<get_all_attributes>. Methods which would alter the class, such as
1723 C<add_attribute>, C<add_method>, and so on will throw an error on an
1724 immutable metaclass object.
1726 The immutabilization system in L<Moose> takes much greater advantage
1727 of the inlining features than Class::MOP itself does.
1731 =item B<< $metaclass->make_immutable(%options) >>
1733 This method will create an immutable transformer and uses it to make
1734 the class and its metaclass object immutable.
1736 This method accepts the following options:
1740 =item * inline_accessors
1742 =item * inline_constructor
1744 =item * inline_destructor
1746 These are all booleans indicating whether the specified method(s)
1749 By default, accessors and the constructor are inlined, but not the
1752 =item * immutable_trait
1754 The name of a class which will be used as a parent class for the
1755 metaclass object being made immutable. This "trait" implements the
1756 post-immutability functionality of the metaclass (but not the
1757 transformation itself).
1759 This defaults to L<Class::MOP::Class::Immutable::Trait>.
1761 =item * constructor_name
1763 This is the constructor method name. This defaults to "new".
1765 =item * constructor_class
1767 The name of the method metaclass for constructors. It will be used to
1768 generate the inlined constructor. This defaults to
1769 "Class::MOP::Method::Constructor".
1771 =item * replace_constructor
1773 This is a boolean indicating whether an existing constructor should be
1774 replaced when inlining a constructor. This defaults to false.
1776 =item * destructor_class
1778 The name of the method metaclass for destructors. It will be used to
1779 generate the inlined destructor. This defaults to
1780 "Class::MOP::Method::Denstructor".
1782 =item * replace_destructor
1784 This is a boolean indicating whether an existing destructor should be
1785 replaced when inlining a destructor. This defaults to false.
1789 =item B<< $metaclass->make_mutable >>
1791 Calling this method reverse the immutabilization transformation.
1795 =head2 Method Modifiers
1797 Method modifiers are hooks which allow a method to be wrapped with
1798 I<before>, I<after> and I<around> method modifiers. Every time a
1799 method is called, it's modifiers are also called.
1801 A class can modify its own methods, as well as methods defined in
1804 =head3 How method modifiers work?
1806 Method modifiers work by wrapping the original method and then
1807 replacing it in the class's symbol table. The wrappers will handle
1808 calling all the modifiers in the appropriate order and preserving the
1809 calling context for the original method.
1811 The return values of C<before> and C<after> modifiers are
1812 ignored. This is because their purpose is B<not> to filter the input
1813 and output of the primary method (this is done with an I<around>
1816 This may seem like an odd restriction to some, but doing this allows
1817 for simple code to be added at the beginning or end of a method call
1818 without altering the function of the wrapped method or placing any
1819 extra responsibility on the code of the modifier.
1821 Of course if you have more complex needs, you can use the C<around>
1822 modifier which allows you to change both the parameters passed to the
1823 wrapped method, as well as its return value.
1825 Before and around modifiers are called in last-defined-first-called
1826 order, while after modifiers are called in first-defined-first-called
1827 order. So the call tree might looks something like this:
1839 =head3 What is the performance impact?
1841 Of course there is a performance cost associated with method
1842 modifiers, but we have made every effort to make that cost directly
1843 proportional to the number of modifier features you utilize.
1845 The wrapping method does it's best to B<only> do as much work as it
1846 absolutely needs to. In order to do this we have moved some of the
1847 performance costs to set-up time, where they are easier to amortize.
1849 All this said, our benchmarks have indicated the following:
1851 simple wrapper with no modifiers 100% slower
1852 simple wrapper with simple before modifier 400% slower
1853 simple wrapper with simple after modifier 450% slower
1854 simple wrapper with simple around modifier 500-550% slower
1855 simple wrapper with all 3 modifiers 1100% slower
1857 These numbers may seem daunting, but you must remember, every feature
1858 comes with some cost. To put things in perspective, just doing a
1859 simple C<AUTOLOAD> which does nothing but extract the name of the
1860 method called and return it costs about 400% over a normal method
1865 =item B<< $metaclass->add_before_method_modifier($method_name, $code) >>
1867 This wraps the specified method with the supplied subroutine
1868 reference. The modifier will be called as a method itself, and will
1869 receive the same arguments as are passed to the method.
1871 When the modifier exits, the wrapped method will be called.
1873 The return value of the modifier will be ignored.
1875 =item B<< $metaclass->add_after_method_modifier($method_name, $code) >>
1877 This wraps the specified method with the supplied subroutine
1878 reference. The modifier will be called as a method itself, and will
1879 receive the same arguments as are passed to the method.
1881 When the wrapped methods exits, the modifier will be called.
1883 The return value of the modifier will be ignored.
1885 =item B<< $metaclass->add_around_method_modifier($method_name, $code) >>
1887 This wraps the specified method with the supplied subroutine
1890 The first argument passed to the modifier will be a subroutine
1891 reference to the wrapped method. The second argument is the object,
1892 and after that come any arguments passed when the method is called.
1894 The around modifier can choose to call the original method, as well as
1895 what arguments to pass if it does so.
1897 The return value of the modifier is what will be seen by the caller.
1901 =head2 Introspection
1905 =item B<< Class::MOP::Class->meta >>
1907 This will return a L<Class::MOP::Class> instance for this class.
1909 It should also be noted that L<Class::MOP> will actually bootstrap
1910 this module by installing a number of attribute meta-objects into its
1917 Stevan Little E<lt>stevan@iinteractive.comE<gt>
1919 =head1 COPYRIGHT AND LICENSE
1921 Copyright 2006-2009 by Infinity Interactive, Inc.
1923 L<http://www.iinteractive.com>
1925 This library is free software; you can redistribute it and/or modify
1926 it under the same terms as Perl itself.