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 sub _method_map { $_[0]->{'methods'} }
352 # Instance Construction & Cloning
358 # we need to protect the integrity of the
359 # Class::MOP::Class singletons here, so we
360 # delegate this to &construct_class_instance
361 # which will deal with the singletons
362 return $class->_construct_class_instance(@_)
363 if $class->name->isa('Class::MOP::Class');
364 return $class->_construct_instance(@_);
367 sub construct_instance {
368 Carp::cluck('The construct_instance method has been made private.'
369 . " The public version is deprecated and will be removed in a future release.\n");
370 shift->_construct_instance(@_);
373 sub _construct_instance {
375 my $params = @_ == 1 ? $_[0] : {@_};
376 my $meta_instance = $class->get_meta_instance();
378 # the code below is almost certainly incorrect
379 # but this is foreign inheritance, so we might
380 # have to kludge it in the end.
381 my $instance = $params->{__INSTANCE__} || $meta_instance->create_instance();
382 foreach my $attr ($class->get_all_attributes()) {
383 $attr->initialize_instance_slot($meta_instance, $instance, $params);
386 # this will only work for a HASH instance type
387 if ($class->is_anon_class) {
388 (Scalar::Util::reftype($instance) eq 'HASH')
389 || confess "Currently only HASH based instances are supported with instance of anon-classes";
391 # At some point we should make this official
392 # as a reserved slot name, but right now I am
393 # going to keep it here.
394 # my $RESERVED_MOP_SLOT = '__MOP__';
395 $instance->{'__MOP__'} = $class;
401 sub get_meta_instance {
403 $self->{'_meta_instance'} ||= $self->_create_meta_instance();
406 sub create_meta_instance {
407 Carp::cluck('The create_meta_instance method has been made private.'
408 . " The public version is deprecated and will be removed in a future release.\n");
409 shift->_create_meta_instance(@_);
412 sub _create_meta_instance {
415 my $instance = $self->instance_metaclass->new(
416 associated_metaclass => $self,
417 attributes => [ $self->get_all_attributes() ],
420 $self->add_meta_instance_dependencies()
421 if $instance->is_dependent_on_superclasses();
428 my $instance = shift;
429 (blessed($instance) && $instance->isa($class->name))
430 || confess "You must pass an instance of the metaclass (" . (ref $class ? $class->name : $class) . "), not ($instance)";
433 # we need to protect the integrity of the
434 # Class::MOP::Class singletons here, they
435 # should not be cloned.
436 return $instance if $instance->isa('Class::MOP::Class');
437 $class->_clone_instance($instance, @_);
441 Carp::cluck('The clone_instance method has been made private.'
442 . " The public version is deprecated and will be removed in a future release.\n");
443 shift->_clone_instance(@_);
446 sub _clone_instance {
447 my ($class, $instance, %params) = @_;
449 || confess "You can only clone instances, ($instance) is not a blessed instance";
450 my $meta_instance = $class->get_meta_instance();
451 my $clone = $meta_instance->clone_instance($instance);
452 foreach my $attr ($class->get_all_attributes()) {
453 if ( defined( my $init_arg = $attr->init_arg ) ) {
454 if (exists $params{$init_arg}) {
455 $attr->set_value($clone, $params{$init_arg});
462 sub rebless_instance {
463 my ($self, $instance, %params) = @_;
465 my $old_metaclass = Class::MOP::class_of($instance);
467 my $old_class = $old_metaclass ? $old_metaclass->name : blessed($instance);
468 $self->name->isa($old_class)
469 || confess "You may rebless only into a subclass of ($old_class), of which (". $self->name .") isn't.";
471 $old_metaclass->rebless_instance_away($instance, $self, %params)
474 my $meta_instance = $self->get_meta_instance();
477 # we use $_[1] here because of t/306_rebless_overload.t regressions on 5.8.8
478 $meta_instance->rebless_instance_structure($_[1], $self);
480 foreach my $attr ( $self->get_all_attributes ) {
481 if ( $attr->has_value($instance) ) {
482 if ( defined( my $init_arg = $attr->init_arg ) ) {
483 $params{$init_arg} = $attr->get_value($instance)
484 unless exists $params{$init_arg};
487 $attr->set_value($instance, $attr->get_value($instance));
492 foreach my $attr ($self->get_all_attributes) {
493 $attr->initialize_instance_slot($meta_instance, $instance, \%params);
499 sub rebless_instance_away {
500 # this intentionally does nothing, it is just a hook
507 my $var_spec = { sigil => '@', type => 'ARRAY', name => 'ISA' };
510 @{$self->get_package_symbol($var_spec)} = @supers;
513 # on 5.8 and below, we need to call
514 # a method to get Perl to detect
515 # a cycle in the class hierarchy
516 my $class = $self->name;
520 # we need to check the metaclass
521 # compatibility here so that we can
522 # be sure that the superclass is
523 # not potentially creating an issues
524 # we don't know about
526 $self->_check_metaclass_compatibility();
527 $self->_superclasses_updated();
529 @{$self->get_package_symbol($var_spec)};
532 sub _superclasses_updated {
534 $self->update_meta_instance_dependencies();
539 my $super_class = $self->name;
541 return @{ $super_class->mro::get_isarev() };
544 sub direct_subclasses {
546 my $super_class = $self->name;
551 } Class::MOP::Class->initialize($_)->superclasses
556 return @{ mro::get_linear_isa( (shift)->name ) };
559 sub class_precedence_list {
561 my $name = $self->name;
563 unless (Class::MOP::IS_RUNNING_ON_5_10()) {
565 # We need to check for circular inheritance here
566 # if we are are not on 5.10, cause 5.8 detects it
567 # late. This will do nothing if all is well, and
568 # blow up otherwise. Yes, it's an ugly hack, better
569 # suggestions are welcome.
571 ($name || return)->isa('This is a test for circular inheritance')
574 # if our mro is c3, we can
575 # just grab the linear_isa
576 if (mro::get_mro($name) eq 'c3') {
577 return @{ mro::get_linear_isa($name) }
581 # we can't grab the linear_isa for dfs
582 # since it has all the duplicates
587 $self->initialize($_)->class_precedence_list()
588 } $self->superclasses()
595 sub wrap_method_body {
596 my ( $self, %args ) = @_;
598 ('CODE' eq ref $args{body})
599 || confess "Your code block must be a CODE reference";
601 $self->method_metaclass->wrap(
602 package_name => $self->name,
608 my ($self, $method_name, $method) = @_;
609 (defined $method_name && $method_name)
610 || confess "You must define a method name";
613 if (blessed($method)) {
614 $body = $method->body;
615 if ($method->package_name ne $self->name) {
616 $method = $method->clone(
617 package_name => $self->name,
619 ) if $method->can('clone');
622 $method->attach_to_class($self);
623 $self->_method_map->{$method_name} = $method;
626 # If a raw code reference is supplied, its method object is not created.
627 # The method object won't be created until required.
632 my ( $current_package, $current_name ) = Class::MOP::get_code_info($body);
634 if ( !defined $current_name || $current_name eq '__ANON__' ) {
635 my $full_method_name = ($self->name . '::' . $method_name);
636 subname($full_method_name => $body);
639 $self->add_package_symbol(
640 { sigil => '&', type => 'CODE', name => $method_name },
646 my $fetch_and_prepare_method = sub {
647 my ($self, $method_name) = @_;
648 my $wrapped_metaclass = $self->wrapped_method_metaclass;
650 my $method = $self->get_method($method_name);
651 # if we dont have local ...
653 # try to find the next method
654 $method = $self->find_next_method_by_name($method_name);
655 # die if it does not exist
657 || confess "The method '$method_name' was not found in the inheritance hierarchy for " . $self->name;
658 # and now make sure to wrap it
659 # even if it is already wrapped
660 # because we need a new sub ref
661 $method = $wrapped_metaclass->wrap($method);
664 # now make sure we wrap it properly
665 $method = $wrapped_metaclass->wrap($method)
666 unless $method->isa($wrapped_metaclass);
668 $self->add_method($method_name => $method);
672 sub add_before_method_modifier {
673 my ($self, $method_name, $method_modifier) = @_;
674 (defined $method_name && $method_name)
675 || confess "You must pass in a method name";
676 my $method = $fetch_and_prepare_method->($self, $method_name);
677 $method->add_before_modifier(
678 subname(':before' => $method_modifier)
682 sub add_after_method_modifier {
683 my ($self, $method_name, $method_modifier) = @_;
684 (defined $method_name && $method_name)
685 || confess "You must pass in a method name";
686 my $method = $fetch_and_prepare_method->($self, $method_name);
687 $method->add_after_modifier(
688 subname(':after' => $method_modifier)
692 sub add_around_method_modifier {
693 my ($self, $method_name, $method_modifier) = @_;
694 (defined $method_name && $method_name)
695 || confess "You must pass in a method name";
696 my $method = $fetch_and_prepare_method->($self, $method_name);
697 $method->add_around_modifier(
698 subname(':around' => $method_modifier)
703 # the methods above used to be named like this:
704 # ${pkg}::${method}:(before|after|around)
705 # but this proved problematic when using one modifier
706 # to wrap multiple methods (something which is likely
707 # to happen pretty regularly IMO). So instead of naming
708 # it like this, I have chosen to just name them purely
709 # with their modifier names, like so:
710 # :(before|after|around)
711 # The fact is that in a stack trace, it will be fairly
712 # evident from the context what method they are attached
713 # to, and so don't need the fully qualified name.
717 Carp::cluck("The alias_method method is deprecated. Use add_method instead.\n");
719 shift->add_method(@_);
723 my($self, $code) = @_;
724 my($code_package, $code_name) = Class::MOP::get_code_info($code);
726 && $code_package eq $self->name
727 || ($code_package eq 'constant' && $code_name eq '__ANON__');
731 my ($self, $method_name) = @_;
732 (defined $method_name && $method_name)
733 || confess "You must define a method name";
735 return defined($self->get_method($method_name));
739 my ($self, $method_name) = @_;
740 (defined $method_name && $method_name)
741 || confess "You must define a method name";
743 my $method_map = $self->_method_map;
744 my $method_object = $method_map->{$method_name};
746 if(!($method_object && $method_object->_is_valid_generation)){
747 my $code = $self->get_package_symbol({
748 name => $method_name,
753 if(!($code && $self->_code_is_mine($code))){
754 delete $method_map->{$method_name};
757 if(!($method_object && $method_object->body == $code)){
758 $method_object = $method_map->{$method_name} = $self->wrap_method_body(
760 name => $method_name,
761 associated_metaclass => $self,
764 $method_object->_update_generation();
767 return $method_object;
771 my ($self, $method_name) = @_;
772 (defined $method_name && $method_name)
773 || confess "You must define a method name";
775 my $removed_method = delete $self->get_method_map->{$method_name};
777 $self->remove_package_symbol(
778 { sigil => '&', type => 'CODE', name => $method_name }
781 $removed_method->detach_from_class if $removed_method;
783 $self->update_package_cache_flag; # still valid, since we just removed the method from the map
785 return $removed_method;
788 sub get_method_list {
790 keys %{$self->get_method_map};
793 sub find_method_by_name {
794 my ($self, $method_name) = @_;
795 (defined $method_name && $method_name)
796 || confess "You must define a method name to find";
797 foreach my $class ($self->linearized_isa) {
798 # fetch the meta-class ...
799 my $meta = $self->initialize($class);
800 return $meta->get_method($method_name)
801 if $meta->has_method($method_name);
806 sub get_all_methods {
808 my %methods = map { %{ $self->initialize($_)->get_method_map } } reverse $self->linearized_isa;
809 return values %methods;
812 sub compute_all_applicable_methods {
813 Carp::cluck('The compute_all_applicable_methods method is deprecated.'
814 . " Use get_all_methods instead.\n");
819 class => $_->package_name,
820 code => $_, # sigh, overloading
822 } shift->get_all_methods(@_);
825 sub get_all_method_names {
828 grep { $uniq{$_}++ == 0 } map { $_->name } $self->get_all_methods;
831 sub find_all_methods_by_name {
832 my ($self, $method_name) = @_;
833 (defined $method_name && $method_name)
834 || confess "You must define a method name to find";
836 foreach my $class ($self->linearized_isa) {
837 # fetch the meta-class ...
838 my $meta = $self->initialize($class);
840 name => $method_name,
842 code => $meta->get_method($method_name)
843 } if $meta->has_method($method_name);
848 sub find_next_method_by_name {
849 my ($self, $method_name) = @_;
850 (defined $method_name && $method_name)
851 || confess "You must define a method name to find";
852 my @cpl = $self->linearized_isa;
853 shift @cpl; # discard ourselves
854 foreach my $class (@cpl) {
855 # fetch the meta-class ...
856 my $meta = $self->initialize($class);
857 return $meta->get_method($method_name)
858 if $meta->has_method($method_name);
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 # then we remove attributes of a conflicting
880 # name here so that we can properly detach
881 # the old attr object, and remove any
882 # accessors it would have generated
883 if ( $self->has_attribute($attribute->name) ) {
884 $self->remove_attribute($attribute->name);
886 $self->invalidate_meta_instances();
889 # get our count of previously inserted attributes and
890 # increment by one so this attribute knows its order
891 my $order = (scalar keys %{$self->get_attribute_map}) - 1;
892 $attribute->_set_insertion_order($order + 1);
894 # then onto installing the new accessors
895 $self->get_attribute_map->{$attribute->name} = $attribute;
897 # invalidate package flag here
901 eval { $attribute->install_accessors() };
905 $self->remove_attribute($attribute->name);
912 sub update_meta_instance_dependencies {
915 if ( $self->{meta_instance_dependencies} ) {
916 return $self->add_meta_instance_dependencies;
920 sub add_meta_instance_dependencies {
923 $self->remove_meta_instance_dependencies;
925 my @attrs = $self->get_all_attributes();
928 my @classes = grep { not $seen{$_->name}++ } map { $_->associated_class } @attrs;
930 foreach my $class ( @classes ) {
931 $class->add_dependent_meta_instance($self);
934 $self->{meta_instance_dependencies} = \@classes;
937 sub remove_meta_instance_dependencies {
940 if ( my $classes = delete $self->{meta_instance_dependencies} ) {
941 foreach my $class ( @$classes ) {
942 $class->remove_dependent_meta_instance($self);
952 sub add_dependent_meta_instance {
953 my ( $self, $metaclass ) = @_;
954 push @{ $self->{dependent_meta_instances} }, $metaclass;
957 sub remove_dependent_meta_instance {
958 my ( $self, $metaclass ) = @_;
959 my $name = $metaclass->name;
960 @$_ = grep { $_->name ne $name } @$_ for $self->{dependent_meta_instances};
963 sub invalidate_meta_instances {
965 $_->invalidate_meta_instance() for $self, @{ $self->{dependent_meta_instances} };
968 sub invalidate_meta_instance {
970 undef $self->{_meta_instance};
974 my ($self, $attribute_name) = @_;
975 (defined $attribute_name && $attribute_name)
976 || confess "You must define an attribute name";
977 exists $self->get_attribute_map->{$attribute_name};
981 my ($self, $attribute_name) = @_;
982 (defined $attribute_name && $attribute_name)
983 || confess "You must define an attribute name";
984 return $self->get_attribute_map->{$attribute_name}
986 # this will return undef anyway, so no need ...
987 # if $self->has_attribute($attribute_name);
991 sub remove_attribute {
992 my ($self, $attribute_name) = @_;
993 (defined $attribute_name && $attribute_name)
994 || confess "You must define an attribute name";
995 my $removed_attribute = $self->get_attribute_map->{$attribute_name};
996 return unless defined $removed_attribute;
997 delete $self->get_attribute_map->{$attribute_name};
998 $self->invalidate_meta_instances();
999 $removed_attribute->remove_accessors();
1000 $removed_attribute->detach_from_class();
1001 return $removed_attribute;
1004 sub get_attribute_list {
1006 keys %{$self->get_attribute_map};
1009 sub get_all_attributes {
1011 my %attrs = map { %{ $self->initialize($_)->get_attribute_map } } reverse $self->linearized_isa;
1012 return values %attrs;
1015 sub compute_all_applicable_attributes {
1016 Carp::cluck('The compute_all_applicable_attributes method has been deprecated.'
1017 . " Use get_all_attributes instead.\n");
1019 shift->get_all_attributes(@_);
1022 sub find_attribute_by_name {
1023 my ($self, $attr_name) = @_;
1024 foreach my $class ($self->linearized_isa) {
1025 # fetch the meta-class ...
1026 my $meta = $self->initialize($class);
1027 return $meta->get_attribute($attr_name)
1028 if $meta->has_attribute($attr_name);
1033 # check if we can reinitialize
1037 # if any local attr is defined
1038 return if $self->get_attribute_list;
1040 # or any non-declared methods
1041 if ( my @methods = values %{ $self->get_method_map } ) {
1042 my $metaclass = $self->method_metaclass;
1043 foreach my $method ( @methods ) {
1044 return if $method->isa("Class::MOP::Method::Generated");
1045 # FIXME do we need to enforce this too? return unless $method->isa($metaclass);
1054 sub is_mutable { 1 }
1055 sub is_immutable { 0 }
1057 sub _immutable_options {
1058 my ( $self, @args ) = @_;
1061 inline_accessors => 1,
1062 inline_constructor => 1,
1063 inline_destructor => 0,
1065 immutable_trait => $self->immutable_trait,
1066 constructor_name => $self->constructor_name,
1067 constructor_class => $self->constructor_class,
1068 destructor_class => $self->destructor_class,
1073 sub make_immutable {
1074 my ( $self, @args ) = @_;
1076 if ( $self->is_mutable ) {
1077 $self->_initialize_immutable( $self->_immutable_options(@args) );
1078 $self->_rebless_as_immutable(@args);
1089 if ( $self->is_immutable ) {
1090 my @args = $self->immutable_options;
1091 $self->_rebless_as_mutable();
1092 $self->_remove_inlined_code(@args);
1093 delete $self->{__immutable};
1101 sub _rebless_as_immutable {
1102 my ( $self, @args ) = @_;
1104 $self->{__immutable}{original_class} = ref $self;
1106 bless $self => $self->_immutable_metaclass(@args);
1109 sub _immutable_metaclass {
1110 my ( $self, %args ) = @_;
1112 if ( my $class = $args{immutable_metaclass} ) {
1116 my $trait = $args{immutable_trait} = $self->immutable_trait
1117 || confess "no immutable trait specified for $self";
1119 my $meta_attr = $self->meta->find_attribute_by_name("immutable_trait");
1123 if ( $meta_attr and $trait eq $meta_attr->default ) {
1124 # if the trait is the same as the default we try and pick a
1125 # predictable name for the immutable metaclass
1126 $class_name = 'Class::MOP::Class::Immutable::' . ref($self);
1129 $class_name = join '::', 'Class::MOP::Class::Immutable::CustomTrait',
1130 $trait, 'ForMetaClass', ref($self);
1134 if Class::MOP::is_class_loaded($class_name);
1136 # If the metaclass is a subclass of CMOP::Class which has had
1137 # metaclass roles applied (via Moose), then we want to make sure
1138 # that we preserve that anonymous class (see Fey::ORM for an
1139 # example of where this matters).
1141 = $self->meta->is_immutable
1142 ? $self->meta->get_mutable_metaclass_name
1145 my $meta = $meta_name->create(
1147 superclasses => [ ref $self ],
1150 Class::MOP::load_class($trait);
1151 for my $meth ( Class::MOP::Class->initialize($trait)->get_all_methods ) {
1152 next if $meta->has_method( $meth->name );
1154 if ( $meta->find_method_by_name( $meth->name ) ) {
1155 $meta->add_around_method_modifier( $meth->name, $meth->body );
1158 $meta->add_method( $meth->name, $meth->clone );
1162 $meta->make_immutable( inline_constructor => 0 );
1167 sub _remove_inlined_code {
1170 $self->remove_method( $_->name ) for $self->_inlined_methods;
1172 delete $self->{__immutable}{inlined_methods};
1175 sub _inlined_methods { @{ $_[0]{__immutable}{inlined_methods} || [] } }
1177 sub _add_inlined_method {
1178 my ( $self, $method ) = @_;
1180 push @{ $self->{__immutable}{inlined_methods} ||= [] }, $method;
1183 sub _initialize_immutable {
1184 my ( $self, %args ) = @_;
1186 $self->{__immutable}{options} = \%args;
1187 $self->_install_inlined_code(%args);
1190 sub _install_inlined_code {
1191 my ( $self, %args ) = @_;
1194 $self->_inline_accessors(%args) if $args{inline_accessors};
1195 $self->_inline_constructor(%args) if $args{inline_constructor};
1196 $self->_inline_destructor(%args) if $args{inline_destructor};
1199 sub _rebless_as_mutable {
1202 bless $self, $self->get_mutable_metaclass_name;
1207 sub _inline_accessors {
1210 foreach my $attr_name ( $self->get_attribute_list ) {
1211 $self->get_attribute($attr_name)->install_accessors(1);
1215 sub _inline_constructor {
1216 my ( $self, %args ) = @_;
1218 my $name = $args{constructor_name};
1220 if ( $self->has_method($name) && !$args{replace_constructor} ) {
1221 my $class = $self->name;
1222 warn "Not inlining a constructor for $class since it defines"
1223 . " its own constructor.\n"
1224 . "If you are certain you don't need to inline your"
1225 . " constructor, specify inline_constructor => 0 in your"
1226 . " call to $class->meta->make_immutable\n";
1230 my $constructor_class = $args{constructor_class};
1232 Class::MOP::load_class($constructor_class);
1234 my $constructor = $constructor_class->new(
1238 package_name => $self->name,
1242 if ( $args{replace_constructor} or $constructor->can_be_inlined ) {
1243 $self->add_method( $name => $constructor );
1244 $self->_add_inlined_method($constructor);
1248 sub _inline_destructor {
1249 my ( $self, %args ) = @_;
1251 ( exists $args{destructor_class} && defined $args{destructor_class} )
1252 || confess "The 'inline_destructor' option is present, but "
1253 . "no destructor class was specified";
1255 if ( $self->has_method('DESTROY') && ! $args{replace_destructor} ) {
1256 my $class = $self->name;
1257 warn "Not inlining a destructor for $class since it defines"
1258 . " its own destructor.\n";
1262 my $destructor_class = $args{destructor_class};
1264 Class::MOP::load_class($destructor_class);
1266 return unless $destructor_class->is_needed($self);
1268 my $destructor = $destructor_class->new(
1271 package_name => $self->name,
1275 if ( $args{replace_destructor} or $destructor->can_be_inlined ) {
1276 $self->add_method( 'DESTROY' => $destructor );
1277 $self->_add_inlined_method($destructor);
1289 Class::MOP::Class - Class Meta Object
1293 # assuming that class Foo
1294 # has been defined, you can
1296 # use this for introspection ...
1298 # add a method to Foo ...
1299 Foo->meta->add_method( 'bar' => sub {...} )
1301 # get a list of all the classes searched
1302 # the method dispatcher in the correct order
1303 Foo->meta->class_precedence_list()
1305 # remove a method from Foo
1306 Foo->meta->remove_method('bar');
1308 # or use this to actually create classes ...
1310 Class::MOP::Class->create(
1313 superclasses => ['Foo'],
1315 Class::MOP::Attribute->new('$bar'),
1316 Class::MOP::Attribute->new('$baz'),
1319 calculate_bar => sub {...},
1320 construct_baz => sub {...}
1327 The Class Protocol is the largest and most complex part of the
1328 Class::MOP meta-object protocol. It controls the introspection and
1329 manipulation of Perl 5 classes, and it can create them as well. The
1330 best way to understand what this module can do, is to read the
1331 documentation for each of its methods.
1335 C<Class::MOP::Class> is a subclass of L<Class::MOP::Module>.
1339 =head2 Class construction
1341 These methods all create new C<Class::MOP::Class> objects. These
1342 objects can represent existing classes, or they can be used to create
1343 new classes from scratch.
1345 The metaclass object for a given class is a singleton. If you attempt
1346 to create a metaclass for the same class twice, you will just get the
1351 =item B<< Class::MOP::Class->create($package_name, %options) >>
1353 This method creates a new C<Class::MOP::Class> object with the given
1354 package name. It accepts a number of options.
1360 An optional version number for the newly created package.
1364 An optional authority for the newly created package.
1366 =item * superclasses
1368 An optional array reference of superclass names.
1372 An optional hash reference of methods for the class. The keys of the
1373 hash reference are method names, and values are subroutine references.
1377 An optional array reference of attributes.
1379 An attribute can be passed as an existing L<Class::MOP::Attribute>
1380 object, I<or> or as a hash reference of options which will be passed
1381 to the attribute metaclass's constructor.
1385 =item B<< Class::MOP::Class->create_anon_class(%options) >>
1387 This method works just like C<< Class::MOP::Class->create >> but it
1388 creates an "anonymous" class. In fact, the class does have a name, but
1389 that name is a unique name generated internally by this module.
1391 It accepts the same C<superclasses>, C<methods>, and C<attributes>
1392 parameters that C<create> accepts.
1394 Anonymous classes are destroyed once the metaclass they are attached
1395 to goes out of scope, and will be removed from Perl's internal symbol
1398 All instances of an anonymous class keep a special reference to the
1399 metaclass object, which prevents the metaclass from going out of scope
1400 while any instances exist.
1402 This only works if the instance if based on a hash reference, however.
1404 =item B<< Class::MOP::Class->initialize($package_name, %options) >>
1406 This method will initialize a C<Class::MOP::Class> object for the
1407 named package. Unlike C<create>, this method I<will not> create a new
1410 The purpose of this method is to retrieve a C<Class::MOP::Class>
1411 object for introspecting an existing class.
1413 If an existing C<Class::MOP::Class> object exists for the named
1414 package, it will be returned, and any options provided will be
1417 If the object does not yet exist, it will be created.
1419 The valid options that can be passed to this method are
1420 C<attribute_metaclass>, C<method_metaclass>,
1421 C<wrapped_method_metaclass>, and C<instance_metaclass>. These are all
1422 optional, and default to the appropriate class in the C<Class::MOP>
1427 =head2 Object instance construction and cloning
1429 These methods are all related to creating and/or cloning object
1434 =item B<< $metaclass->clone_object($instance, %params) >>
1436 This method clones an existing object instance. Any parameters you
1437 provide are will override existing attribute values in the object.
1439 This is a convenience method for cloning an object instance, then
1440 blessing it into the appropriate package.
1442 You could implement a clone method in your class, using this method:
1445 my ($self, %params) = @_;
1446 $self->meta->clone_object($self, %params);
1449 =item B<< $metaclass->rebless_instance($instance, %params) >>
1451 This method changes the class of C<$instance> to the metaclass's class.
1453 You can only rebless an instance into a subclass of its current
1454 class. If you pass any additional parameters, these will be treated
1455 like constructor parameters and used to initialize the object's
1456 attributes. Any existing attributes that are already set will be
1459 Before reblessing the instance, this method will call
1460 C<rebless_instance_away> on the instance's current metaclass. This method
1461 will be passed the instance, the new metaclass, and any parameters
1462 specified to C<rebless_instance>. By default, C<rebless_instance_away>
1463 does nothing; it is merely a hook.
1465 =item B<< $metaclass->new_object(%params) >>
1467 This method is used to create a new object of the metaclass's
1468 class. Any parameters you provide are used to initialize the
1469 instance's attributes. A special C<__INSTANCE__> key can be passed to
1470 provide an already generated instance, rather than having Class::MOP
1471 generate it for you. This is mostly useful for using Class::MOP with
1472 foreign classes, which generally generate instances using their own
1475 =item B<< $metaclass->instance_metaclass >>
1477 Returns the class name of the instance metaclass, see
1478 L<Class::MOP::Instance> for more information on the instance
1481 =item B<< $metaclass->get_meta_instance >>
1483 Returns an instance of the C<instance_metaclass> to be used in the
1484 construction of a new instance of the class.
1488 =head2 Informational predicates
1490 These are a few predicate methods for asking information about the
1495 =item B<< $metaclass->is_anon_class >>
1497 This returns true if the class was created by calling C<<
1498 Class::MOP::Class->create_anon_class >>.
1500 =item B<< $metaclass->is_mutable >>
1502 This returns true if the class is still mutable.
1504 =item B<< $metaclass->is_immutable >>
1506 This returns true if the class has been made immutable.
1508 =item B<< $metaclass->is_pristine >>
1510 A class is I<not> pristine if it has non-inherited attributes or if it
1511 has any generated methods.
1515 =head2 Inheritance Relationships
1519 =item B<< $metaclass->superclasses(@superclasses) >>
1521 This is a read-write accessor which represents the superclass
1522 relationships of the metaclass's class.
1524 This is basically sugar around getting and setting C<@ISA>.
1526 =item B<< $metaclass->class_precedence_list >>
1528 This returns a list of all of the class's ancestor classes. The
1529 classes are returned in method dispatch order.
1531 =item B<< $metaclass->linearized_isa >>
1533 This returns a list based on C<class_precedence_list> but with all
1536 =item B<< $metaclass->subclasses >>
1538 This returns a list of all subclasses for this class, even indirect
1541 =item B<< $metaclass->direct_subclasses >>
1543 This returns a list of immediate subclasses for this class, which does not
1544 include indirect subclasses.
1548 =head2 Method introspection and creation
1550 These methods allow you to introspect a class's methods, as well as
1551 add, remove, or change methods.
1553 Determining what is truly a method in a Perl 5 class requires some
1554 heuristics (aka guessing).
1556 Methods defined outside the package with a fully qualified name (C<sub
1557 Package::name { ... }>) will be included. Similarly, methods named
1558 with a fully qualified name using L<Sub::Name> are also included.
1560 However, we attempt to ignore imported functions.
1562 Ultimately, we are using heuristics to determine what truly is a
1563 method in a class, and these heuristics may get the wrong answer in
1564 some edge cases. However, for most "normal" cases the heuristics work
1569 =item B<< $metaclass->get_method($method_name) >>
1571 This will return a L<Class::MOP::Method> for the specified
1572 C<$method_name>. If the class does not have the specified method, it
1575 =item B<< $metaclass->has_method($method_name) >>
1577 Returns a boolean indicating whether or not the class defines the
1578 named method. It does not include methods inherited from parent
1581 =item B<< $metaclass->get_method_map >>
1583 Returns a hash reference representing the methods defined in this
1584 class. The keys are method names and the values are
1585 L<Class::MOP::Method> objects.
1587 =item B<< $metaclass->get_method_list >>
1589 This will return a list of method I<names> for all methods defined in
1592 =item B<< $metaclass->get_all_methods >>
1594 This will traverse the inheritance hierarchy and return a list of all
1595 the L<Class::MOP::Method> objects for this class and its parents.
1597 =item B<< $metaclass->find_method_by_name($method_name) >>
1599 This will return a L<Class::MOP::Method> for the specified
1600 C<$method_name>. If the class does not have the specified method, it
1603 Unlike C<get_method>, this method I<will> look for the named method in
1606 =item B<< $metaclass->get_all_method_names >>
1608 This will return a list of method I<names> for all of this class's
1609 methods, including inherited methods.
1611 =item B<< $metaclass->find_all_methods_by_name($method_name) >>
1613 This method looks for the named method in the class and all of its
1614 parents. It returns every matching method it finds in the inheritance
1615 tree, so it returns a list of methods.
1617 Each method is returned as a hash reference with three keys. The keys
1618 are C<name>, C<class>, and C<code>. The C<code> key has a
1619 L<Class::MOP::Method> object as its value.
1621 The list of methods is distinct.
1623 =item B<< $metaclass->find_next_method_by_name($method_name) >>
1625 This method returns the first method in any superclass matching the
1626 given name. It is effectively the method that C<SUPER::$method_name>
1629 =item B<< $metaclass->add_method($method_name, $method) >>
1631 This method takes a method name and a subroutine reference, and adds
1632 the method to the class.
1634 The subroutine reference can be a L<Class::MOP::Method>, and you are
1635 strongly encouraged to pass a meta method object instead of a code
1636 reference. If you do so, that object gets stored as part of the
1637 class's method map directly. If not, the meta information will have to
1638 be recreated later, and may be incorrect.
1640 If you provide a method object, this method will clone that object if
1641 the object's package name does not match the class name. This lets us
1642 track the original source of any methods added from other classes
1643 (notably Moose roles).
1645 =item B<< $metaclass->remove_method($method_name) >>
1647 Remove the named method from the class. This method returns the
1648 L<Class::MOP::Method> object for the method.
1650 =item B<< $metaclass->method_metaclass >>
1652 Returns the class name of the method metaclass, see
1653 L<Class::MOP::Method> for more information on the method metaclass.
1655 =item B<< $metaclass->wrapped_method_metaclass >>
1657 Returns the class name of the wrapped method metaclass, see
1658 L<Class::MOP::Method::Wrapped> for more information on the wrapped
1663 =head2 Attribute introspection and creation
1665 Because Perl 5 does not have a core concept of attributes in classes,
1666 we can only return information about attributes which have been added
1667 via this class's methods. We cannot discover information about
1668 attributes which are defined in terms of "regular" Perl 5 methods.
1672 =item B<< $metaclass->get_attribute($attribute_name) >>
1674 This will return a L<Class::MOP::Attribute> for the specified
1675 C<$attribute_name>. If the class does not have the specified
1676 attribute, it returns C<undef>.
1678 NOTE that get_attribute does not search superclasses, for that you
1679 need to use C<find_attribute_by_name>.
1681 =item B<< $metaclass->has_attribute($attribute_name) >>
1683 Returns a boolean indicating whether or not the class defines the
1684 named attribute. It does not include attributes inherited from parent
1687 =item B<< $metaclass->get_attribute_map >>
1689 Returns a hash reference representing the attributes defined in this
1690 class. The keys are attribute names and the values are
1691 L<Class::MOP::Attribute> objects.
1693 =item B<< $metaclass->get_attribute_list >>
1695 This will return a list of attributes I<names> for all attributes
1696 defined in this class.
1698 =item B<< $metaclass->get_all_attributes >>
1700 This will traverse the inheritance hierarchy and return a list of all
1701 the L<Class::MOP::Attribute> objects for this class and its parents.
1703 =item B<< $metaclass->find_attribute_by_name($attribute_name) >>
1705 This will return a L<Class::MOP::Attribute> for the specified
1706 C<$attribute_name>. If the class does not have the specified
1707 attribute, it returns C<undef>
1709 Unlike C<get_attribute>, this attribute I<will> look for the named
1710 attribute in superclasses.
1712 =item B<< $metaclass->add_attribute(...) >>
1714 This method accepts either an existing L<Class::MOP::Attribute>
1715 object, or parameters suitable for passing to that class's C<new>
1718 The attribute provided will be added to the class.
1720 Any accessor methods defined by the attribute will be added to the
1721 class when the attribute is added.
1723 If an attribute of the same name already exists, the old attribute
1724 will be removed first.
1726 =item B<< $metaclass->remove_attribute($attribute_name) >>
1728 This will remove the named attribute from the class, and
1729 L<Class::MOP::Attribute> object.
1731 Removing an attribute also removes any accessor methods defined by the
1734 However, note that removing an attribute will only affect I<future>
1735 object instances created for this class, not existing instances.
1737 =item B<< $metaclass->attribute_metaclass >>
1739 Returns the class name of the attribute metaclass for this class. By
1740 default, this is L<Class::MOP::Attribute>. for more information on
1744 =head2 Class Immutability
1746 Making a class immutable "freezes" the class definition. You can no
1747 longer call methods which alter the class, such as adding or removing
1748 methods or attributes.
1750 Making a class immutable lets us optimize the class by inlining some
1751 methods, and also allows us to optimize some methods on the metaclass
1754 After immutabilization, the metaclass object will cache most
1755 informational methods such as C<get_method_map> and
1756 C<get_all_attributes>. Methods which would alter the class, such as
1757 C<add_attribute>, C<add_method>, and so on will throw an error on an
1758 immutable metaclass object.
1760 The immutabilization system in L<Moose> takes much greater advantage
1761 of the inlining features than Class::MOP itself does.
1765 =item B<< $metaclass->make_immutable(%options) >>
1767 This method will create an immutable transformer and uses it to make
1768 the class and its metaclass object immutable.
1770 This method accepts the following options:
1774 =item * inline_accessors
1776 =item * inline_constructor
1778 =item * inline_destructor
1780 These are all booleans indicating whether the specified method(s)
1783 By default, accessors and the constructor are inlined, but not the
1786 =item * immutable_trait
1788 The name of a class which will be used as a parent class for the
1789 metaclass object being made immutable. This "trait" implements the
1790 post-immutability functionality of the metaclass (but not the
1791 transformation itself).
1793 This defaults to L<Class::MOP::Class::Immutable::Trait>.
1795 =item * constructor_name
1797 This is the constructor method name. This defaults to "new".
1799 =item * constructor_class
1801 The name of the method metaclass for constructors. It will be used to
1802 generate the inlined constructor. This defaults to
1803 "Class::MOP::Method::Constructor".
1805 =item * replace_constructor
1807 This is a boolean indicating whether an existing constructor should be
1808 replaced when inlining a constructor. This defaults to false.
1810 =item * destructor_class
1812 The name of the method metaclass for destructors. It will be used to
1813 generate the inlined destructor. This defaults to
1814 "Class::MOP::Method::Denstructor".
1816 =item * replace_destructor
1818 This is a boolean indicating whether an existing destructor should be
1819 replaced when inlining a destructor. This defaults to false.
1823 =item B<< $metaclass->make_mutable >>
1825 Calling this method reverse the immutabilization transformation.
1829 =head2 Method Modifiers
1831 Method modifiers are hooks which allow a method to be wrapped with
1832 I<before>, I<after> and I<around> method modifiers. Every time a
1833 method is called, it's modifiers are also called.
1835 A class can modify its own methods, as well as methods defined in
1838 =head3 How method modifiers work?
1840 Method modifiers work by wrapping the original method and then
1841 replacing it in the class's symbol table. The wrappers will handle
1842 calling all the modifiers in the appropriate order and preserving the
1843 calling context for the original method.
1845 The return values of C<before> and C<after> modifiers are
1846 ignored. This is because their purpose is B<not> to filter the input
1847 and output of the primary method (this is done with an I<around>
1850 This may seem like an odd restriction to some, but doing this allows
1851 for simple code to be added at the beginning or end of a method call
1852 without altering the function of the wrapped method or placing any
1853 extra responsibility on the code of the modifier.
1855 Of course if you have more complex needs, you can use the C<around>
1856 modifier which allows you to change both the parameters passed to the
1857 wrapped method, as well as its return value.
1859 Before and around modifiers are called in last-defined-first-called
1860 order, while after modifiers are called in first-defined-first-called
1861 order. So the call tree might looks something like this:
1873 =head3 What is the performance impact?
1875 Of course there is a performance cost associated with method
1876 modifiers, but we have made every effort to make that cost directly
1877 proportional to the number of modifier features you utilize.
1879 The wrapping method does it's best to B<only> do as much work as it
1880 absolutely needs to. In order to do this we have moved some of the
1881 performance costs to set-up time, where they are easier to amortize.
1883 All this said, our benchmarks have indicated the following:
1885 simple wrapper with no modifiers 100% slower
1886 simple wrapper with simple before modifier 400% slower
1887 simple wrapper with simple after modifier 450% slower
1888 simple wrapper with simple around modifier 500-550% slower
1889 simple wrapper with all 3 modifiers 1100% slower
1891 These numbers may seem daunting, but you must remember, every feature
1892 comes with some cost. To put things in perspective, just doing a
1893 simple C<AUTOLOAD> which does nothing but extract the name of the
1894 method called and return it costs about 400% over a normal method
1899 =item B<< $metaclass->add_before_method_modifier($method_name, $code) >>
1901 This wraps the specified method with the supplied subroutine
1902 reference. The modifier will be called as a method itself, and will
1903 receive the same arguments as are passed to the method.
1905 When the modifier exits, the wrapped method will be called.
1907 The return value of the modifier will be ignored.
1909 =item B<< $metaclass->add_after_method_modifier($method_name, $code) >>
1911 This wraps the specified method with the supplied subroutine
1912 reference. The modifier will be called as a method itself, and will
1913 receive the same arguments as are passed to the method.
1915 When the wrapped methods exits, the modifier will be called.
1917 The return value of the modifier will be ignored.
1919 =item B<< $metaclass->add_around_method_modifier($method_name, $code) >>
1921 This wraps the specified method with the supplied subroutine
1924 The first argument passed to the modifier will be a subroutine
1925 reference to the wrapped method. The second argument is the object,
1926 and after that come any arguments passed when the method is called.
1928 The around modifier can choose to call the original method, as well as
1929 what arguments to pass if it does so.
1931 The return value of the modifier is what will be seen by the caller.
1935 =head2 Introspection
1939 =item B<< Class::MOP::Class->meta >>
1941 This will return a L<Class::MOP::Class> instance for this class.
1943 It should also be noted that L<Class::MOP> will actually bootstrap
1944 this module by installing a number of attribute meta-objects into its
1951 Stevan Little E<lt>stevan@iinteractive.comE<gt>
1953 =head1 COPYRIGHT AND LICENSE
1955 Copyright 2006-2009 by Infinity Interactive, Inc.
1957 L<http://www.iinteractive.com>
1959 This library is free software; you can redistribute it and/or modify
1960 it under the same terms as Perl itself.