2 package Class::MOP::Class;
7 use Class::MOP::Immutable;
8 use Class::MOP::Instance;
9 use Class::MOP::Method::Wrapped;
12 use Scalar::Util 'blessed', 'weaken';
14 our $VERSION = '0.75';
15 $VERSION = eval $VERSION;
16 our $AUTHORITY = 'cpan:STEVAN';
18 use base 'Class::MOP::Module';
28 $package_name = shift;
31 $package_name = $options{package};
34 (defined $package_name && $package_name && !ref($package_name))
35 || confess "You must pass a package name and it cannot be blessed";
37 return Class::MOP::get_metaclass_by_name($package_name)
38 || $class->construct_class_instance(package => $package_name, @_);
41 # NOTE: (meta-circularity)
42 # this is a special form of &construct_instance
43 # (see below), which is used to construct class
44 # meta-object instances for any Class::MOP::*
45 # class. All other classes will use the more
46 # normal &construct_instance.
47 sub construct_class_instance {
49 my $options = @_ == 1 ? $_[0] : {@_};
50 my $package_name = $options->{package};
51 (defined $package_name && $package_name)
52 || confess "You must pass a package name";
54 # return the metaclass if we have it cached,
55 # and it is still defined (it has not been
56 # reaped by DESTROY yet, which can happen
57 # annoyingly enough during global destruction)
59 if (defined(my $meta = Class::MOP::get_metaclass_by_name($package_name))) {
64 # we need to deal with the possibility
65 # of class immutability here, and then
66 # get the name of the class appropriately
68 ? ($class->is_immutable
69 ? $class->get_mutable_metaclass_name()
73 # now create the metaclass
75 if ($class eq 'Class::MOP::Class') {
77 $meta = $class->_new($options)
81 # it is safe to use meta here because
82 # class will always be a subclass of
83 # Class::MOP::Class, which defines meta
84 $meta = $class->meta->construct_instance($options)
87 # and check the metaclass compatibility
88 $meta->check_metaclass_compatibility();
90 Class::MOP::store_metaclass_by_name($package_name, $meta);
93 # we need to weaken any anon classes
94 # so that they can call DESTROY properly
95 Class::MOP::weaken_metaclass($package_name) if $meta->is_anon_class;
102 my $options = @_ == 1 ? $_[0] : {@_};
105 # inherited from Class::MOP::Package
106 'package' => $options->{package},
109 # since the following attributes will
110 # actually be loaded from the symbol
111 # table, and actually bypass the instance
112 # entirely, we can just leave these things
113 # listed here for reference, because they
114 # should not actually have a value associated
116 'namespace' => \undef,
117 # inherited from Class::MOP::Module
119 'authority' => \undef,
120 # defined in Class::MOP::Class
121 'superclasses' => \undef,
125 'attribute_metaclass' => $options->{'attribute_metaclass'} || 'Class::MOP::Attribute',
126 'method_metaclass' => $options->{'method_metaclass'} || 'Class::MOP::Method',
127 'instance_metaclass' => $options->{'instance_metaclass'} || 'Class::MOP::Instance',
131 sub reset_package_cache_flag { (shift)->{'_package_cache_flag'} = undef }
132 sub update_package_cache_flag {
135 # we can manually update the cache number
136 # since we are actually adding the method
137 # to our cache as well. This avoids us
138 # having to regenerate the method_map.
140 $self->{'_package_cache_flag'} = Class::MOP::check_package_cache_flag($self->name);
143 sub check_metaclass_compatibility {
146 # this is always okay ...
147 return if ref($self) eq 'Class::MOP::Class' &&
148 $self->instance_metaclass eq 'Class::MOP::Instance';
150 my @class_list = $self->linearized_isa;
151 shift @class_list; # shift off $self->name
153 foreach my $class_name (@class_list) {
154 my $meta = Class::MOP::get_metaclass_by_name($class_name) || next;
157 # we need to deal with the possibility
158 # of class immutability here, and then
159 # get the name of the class appropriately
160 my $meta_type = ($meta->is_immutable
161 ? $meta->get_mutable_metaclass_name()
164 ($self->isa($meta_type))
165 || confess $self->name . "->meta => (" . (ref($self)) . ")" .
166 " is not compatible with the " .
167 $class_name . "->meta => (" . ($meta_type) . ")";
169 # we also need to check that instance metaclasses
170 # are compatibile in the same the class.
171 ($self->instance_metaclass->isa($meta->instance_metaclass))
172 || confess $self->name . "->meta->instance_metaclass => (" . ($self->instance_metaclass) . ")" .
173 " is not compatible with the " .
174 $class_name . "->meta->instance_metaclass => (" . ($meta->instance_metaclass) . ")";
178 # backwards compat for stevan's inability to spell ;)
179 sub check_metaclass_compatability {
181 $self->check_metaclass_compatibility(@_);
188 # this should be sufficient, if you have a
189 # use case where it is not, write a test and
191 my $ANON_CLASS_SERIAL = 0;
194 # we need a sufficiently annoying prefix
195 # this should suffice for now, this is
196 # used in a couple of places below, so
197 # need to put it up here for now.
198 my $ANON_CLASS_PREFIX = 'Class::MOP::Class::__ANON__::SERIAL::';
202 no warnings 'uninitialized';
203 $self->name =~ /^$ANON_CLASS_PREFIX/;
206 sub create_anon_class {
207 my ($class, %options) = @_;
208 my $package_name = $ANON_CLASS_PREFIX . ++$ANON_CLASS_SERIAL;
209 return $class->create($package_name, %options);
213 # this will only get called for
214 # anon-classes, all other calls
215 # are assumed to occur during
216 # global destruction and so don't
217 # really need to be handled explicitly
221 return if Class::MOP::in_global_destruction(); # it'll happen soon anyway and this just makes things more complicated
223 no warnings 'uninitialized';
224 return unless $self->name =~ /^$ANON_CLASS_PREFIX/;
225 # Moose does a weird thing where it replaces the metaclass for
226 # class when fixing metaclass incompatibility. In that case,
227 # we don't want to clean out the namespace now. We can detect
228 # that because Moose will explicitly update the singleton
229 # cache in Class::MOP.
230 my $current_meta = Class::MOP::get_metaclass_by_name($self->name);
231 return if $current_meta ne $self;
233 my ($serial_id) = ($self->name =~ /^$ANON_CLASS_PREFIX(\d+)/);
235 foreach my $key (keys %{$ANON_CLASS_PREFIX . $serial_id}) {
236 delete ${$ANON_CLASS_PREFIX . $serial_id}{$key};
238 delete ${'main::' . $ANON_CLASS_PREFIX}{$serial_id . '::'};
243 # creating classes with MOP ...
246 my ( $class, @args ) = @_;
248 unshift @args, 'package' if @args % 2 == 1;
250 my (%options) = @args;
251 my $package_name = $options{package};
253 (ref $options{superclasses} eq 'ARRAY')
254 || confess "You must pass an ARRAY ref of superclasses"
255 if exists $options{superclasses};
257 (ref $options{attributes} eq 'ARRAY')
258 || confess "You must pass an ARRAY ref of attributes"
259 if exists $options{attributes};
261 (ref $options{methods} eq 'HASH')
262 || confess "You must pass a HASH ref of methods"
263 if exists $options{methods};
265 $class->SUPER::create(%options);
267 my (%initialize_options) = @args;
268 delete @initialize_options{qw(
276 my $meta = $class->initialize( $package_name => %initialize_options );
279 $meta->add_method('meta' => sub {
280 $class->initialize(ref($_[0]) || $_[0]);
283 $meta->superclasses(@{$options{superclasses}})
284 if exists $options{superclasses};
286 # process attributes first, so that they can
287 # install accessors, but locally defined methods
288 # can then overwrite them. It is maybe a little odd, but
289 # I think this should be the order of things.
290 if (exists $options{attributes}) {
291 foreach my $attr (@{$options{attributes}}) {
292 $meta->add_attribute($attr);
295 if (exists $options{methods}) {
296 foreach my $method_name (keys %{$options{methods}}) {
297 $meta->add_method($method_name, $options{methods}->{$method_name});
306 # all these attribute readers will be bootstrapped
307 # away in the Class::MOP bootstrap section
309 sub get_attribute_map { $_[0]->{'attributes'} }
310 sub attribute_metaclass { $_[0]->{'attribute_metaclass'} }
311 sub method_metaclass { $_[0]->{'method_metaclass'} }
312 sub instance_metaclass { $_[0]->{'instance_metaclass'} }
317 my $class_name = $self->name;
319 my $current = Class::MOP::check_package_cache_flag($class_name);
321 if (defined $self->{'_package_cache_flag'} && $self->{'_package_cache_flag'} == $current) {
322 return $self->{'methods'} ||= {};
325 $self->{_package_cache_flag} = $current;
327 my $map = $self->{'methods'} ||= {};
329 my $method_metaclass = $self->method_metaclass;
331 my $all_code = $self->get_all_package_symbols('CODE');
333 foreach my $symbol (keys %{ $all_code }) {
334 my $code = $all_code->{$symbol};
336 next if exists $map->{$symbol} &&
337 defined $map->{$symbol} &&
338 $map->{$symbol}->body == $code;
340 my ($pkg, $name) = Class::MOP::get_code_info($code);
343 # in 5.10 constant.pm the constants show up
344 # as being in the right package, but in pre-5.10
345 # they show up as constant::__ANON__ so we
346 # make an exception here to be sure that things
347 # work as expected in both.
349 unless ($pkg eq 'constant' && $name eq '__ANON__') {
350 next if ($pkg || '') ne $class_name ||
351 (($name || '') ne '__ANON__' && ($pkg || '') ne $class_name);
354 $map->{$symbol} = $method_metaclass->wrap(
356 associated_metaclass => $self,
357 package_name => $class_name,
365 # Instance Construction & Cloning
371 # we need to protect the integrity of the
372 # Class::MOP::Class singletons here, so we
373 # delegate this to &construct_class_instance
374 # which will deal with the singletons
375 return $class->construct_class_instance(@_)
376 if $class->name->isa('Class::MOP::Class');
377 return $class->construct_instance(@_);
380 sub construct_instance {
382 my $params = @_ == 1 ? $_[0] : {@_};
383 my $meta_instance = $class->get_meta_instance();
384 my $instance = $meta_instance->create_instance();
385 foreach my $attr ($class->compute_all_applicable_attributes()) {
386 $attr->initialize_instance_slot($meta_instance, $instance, $params);
389 # this will only work for a HASH instance type
390 if ($class->is_anon_class) {
391 (Scalar::Util::reftype($instance) eq 'HASH')
392 || confess "Currently only HASH based instances are supported with instance of anon-classes";
394 # At some point we should make this official
395 # as a reserved slot name, but right now I am
396 # going to keep it here.
397 # my $RESERVED_MOP_SLOT = '__MOP__';
398 $instance->{'__MOP__'} = $class;
404 sub get_meta_instance {
406 $self->{'_meta_instance'} ||= $self->create_meta_instance();
409 sub create_meta_instance {
412 my $instance = $self->instance_metaclass->new(
413 associated_metaclass => $self,
414 attributes => [ $self->compute_all_applicable_attributes() ],
417 $self->add_meta_instance_dependencies()
418 if $instance->is_dependent_on_superclasses();
425 my $instance = shift;
426 (blessed($instance) && $instance->isa($class->name))
427 || confess "You must pass an instance of the metaclass (" . (ref $class ? $class->name : $class) . "), not ($instance)";
430 # we need to protect the integrity of the
431 # Class::MOP::Class singletons here, they
432 # should not be cloned.
433 return $instance if $instance->isa('Class::MOP::Class');
434 $class->clone_instance($instance, @_);
438 my ($class, $instance, %params) = @_;
440 || confess "You can only clone instances, ($instance) is not a blessed instance";
441 my $meta_instance = $class->get_meta_instance();
442 my $clone = $meta_instance->clone_instance($instance);
443 foreach my $attr ($class->compute_all_applicable_attributes()) {
444 if ( defined( my $init_arg = $attr->init_arg ) ) {
445 if (exists $params{$init_arg}) {
446 $attr->set_value($clone, $params{$init_arg});
453 sub rebless_instance {
454 my ($self, $instance, %params) = @_;
457 if ($instance->can('meta')) {
458 ($instance->meta->isa('Class::MOP::Class'))
459 || confess 'Cannot rebless instance if ->meta is not an instance of Class::MOP::Class';
460 $old_metaclass = $instance->meta;
463 $old_metaclass = $self->initialize(ref($instance));
466 my $meta_instance = $self->get_meta_instance();
468 $self->name->isa($old_metaclass->name)
469 || confess "You may rebless only into a subclass of (". $old_metaclass->name ."), of which (". $self->name .") isn't.";
472 $meta_instance->rebless_instance_structure($instance, $self);
474 foreach my $attr ( $self->compute_all_applicable_attributes ) {
475 if ( $attr->has_value($instance) ) {
476 if ( defined( my $init_arg = $attr->init_arg ) ) {
477 $params{$init_arg} = $attr->get_value($instance)
478 unless exists $params{$init_arg};
481 $attr->set_value($instance, $attr->get_value($instance));
486 foreach my $attr ($self->compute_all_applicable_attributes) {
487 $attr->initialize_instance_slot($meta_instance, $instance, \%params);
497 my $var_spec = { sigil => '@', type => 'ARRAY', name => 'ISA' };
500 @{$self->get_package_symbol($var_spec)} = @supers;
503 # on 5.8 and below, we need to call
504 # a method to get Perl to detect
505 # a cycle in the class hierarchy
506 my $class = $self->name;
510 # we need to check the metaclass
511 # compatibility here so that we can
512 # be sure that the superclass is
513 # not potentially creating an issues
514 # we don't know about
516 $self->check_metaclass_compatibility();
517 $self->update_meta_instance_dependencies();
519 @{$self->get_package_symbol($var_spec)};
525 my $super_class = $self->name;
527 if ( Class::MOP::HAVE_ISAREV() ) {
528 return @{ $super_class->mro::get_isarev() };
532 my $find_derived_classes;
533 $find_derived_classes = sub {
534 my ($outer_class) = @_;
536 my $symbol_table_hashref = do { no strict 'refs'; \%{"${outer_class}::"} };
539 for my $symbol ( keys %$symbol_table_hashref ) {
540 next SYMBOL if $symbol !~ /\A (\w+):: \z/x;
541 my $inner_class = $1;
543 next SYMBOL if $inner_class eq 'SUPER'; # skip '*::SUPER'
547 ? "${outer_class}::$inner_class"
550 if ( $class->isa($super_class) and $class ne $super_class ) {
551 push @derived_classes, $class;
554 next SYMBOL if $class eq 'main'; # skip 'main::*'
556 $find_derived_classes->($class);
560 my $root_class = q{};
561 $find_derived_classes->($root_class);
563 undef $find_derived_classes;
565 @derived_classes = sort { $a->isa($b) ? 1 : $b->isa($a) ? -1 : 0 } @derived_classes;
567 return @derived_classes;
573 return @{ mro::get_linear_isa( (shift)->name ) };
576 sub class_precedence_list {
578 my $name = $self->name;
580 unless (Class::MOP::IS_RUNNING_ON_5_10()) {
582 # We need to check for circular inheritance here
583 # if we are are not on 5.10, cause 5.8 detects it
584 # late. This will do nothing if all is well, and
585 # blow up otherwise. Yes, it's an ugly hack, better
586 # suggestions are welcome.
588 ($name || return)->isa('This is a test for circular inheritance')
591 # if our mro is c3, we can
592 # just grab the linear_isa
593 if (mro::get_mro($name) eq 'c3') {
594 return @{ mro::get_linear_isa($name) }
598 # we can't grab the linear_isa for dfs
599 # since it has all the duplicates
604 $self->initialize($_)->class_precedence_list()
605 } $self->superclasses()
612 sub wrap_method_body {
613 my ( $self, %args ) = @_;
615 ('CODE' eq ref $args{body})
616 || confess "Your code block must be a CODE reference";
618 $self->method_metaclass->wrap(
619 package_name => $self->name,
625 my ($self, $method_name, $method) = @_;
626 (defined $method_name && $method_name)
627 || confess "You must define a method name";
630 if (blessed($method)) {
631 $body = $method->body;
632 if ($method->package_name ne $self->name) {
633 $method = $method->clone(
634 package_name => $self->name,
636 ) if $method->can('clone');
641 $method = $self->wrap_method_body( body => $body, name => $method_name );
644 $method->attach_to_class($self);
646 # This used to call get_method_map, which meant we would build all
647 # the method objects for the class just because we added one
648 # method. This is hackier, but quicker too.
649 $self->{methods}{$method_name} = $method;
651 my $full_method_name = ($self->name . '::' . $method_name);
652 $self->add_package_symbol(
653 { sigil => '&', type => 'CODE', name => $method_name },
654 Class::MOP::subname($full_method_name => $body)
659 my $fetch_and_prepare_method = sub {
660 my ($self, $method_name) = @_;
662 my $method = $self->get_method($method_name);
663 # if we dont have local ...
665 # try to find the next method
666 $method = $self->find_next_method_by_name($method_name);
667 # die if it does not exist
669 || confess "The method '$method_name' is not found in the inheritance hierarchy for class " . $self->name;
670 # and now make sure to wrap it
671 # even if it is already wrapped
672 # because we need a new sub ref
673 $method = Class::MOP::Method::Wrapped->wrap($method);
676 # now make sure we wrap it properly
677 $method = Class::MOP::Method::Wrapped->wrap($method)
678 unless $method->isa('Class::MOP::Method::Wrapped');
680 $self->add_method($method_name => $method);
684 sub add_before_method_modifier {
685 my ($self, $method_name, $method_modifier) = @_;
686 (defined $method_name && $method_name)
687 || confess "You must pass in a method name";
688 my $method = $fetch_and_prepare_method->($self, $method_name);
689 $method->add_before_modifier(
690 Class::MOP::subname(':before' => $method_modifier)
694 sub add_after_method_modifier {
695 my ($self, $method_name, $method_modifier) = @_;
696 (defined $method_name && $method_name)
697 || confess "You must pass in a method name";
698 my $method = $fetch_and_prepare_method->($self, $method_name);
699 $method->add_after_modifier(
700 Class::MOP::subname(':after' => $method_modifier)
704 sub add_around_method_modifier {
705 my ($self, $method_name, $method_modifier) = @_;
706 (defined $method_name && $method_name)
707 || confess "You must pass in a method name";
708 my $method = $fetch_and_prepare_method->($self, $method_name);
709 $method->add_around_modifier(
710 Class::MOP::subname(':around' => $method_modifier)
715 # the methods above used to be named like this:
716 # ${pkg}::${method}:(before|after|around)
717 # but this proved problematic when using one modifier
718 # to wrap multiple methods (something which is likely
719 # to happen pretty regularly IMO). So instead of naming
720 # it like this, I have chosen to just name them purely
721 # with their modifier names, like so:
722 # :(before|after|around)
723 # The fact is that in a stack trace, it will be fairly
724 # evident from the context what method they are attached
725 # to, and so don't need the fully qualified name.
731 $self->add_method(@_);
735 my ($self, $method_name) = @_;
736 (defined $method_name && $method_name)
737 || confess "You must define a method name";
739 exists $self->{methods}{$method_name} || exists $self->get_method_map->{$method_name};
743 my ($self, $method_name) = @_;
744 (defined $method_name && $method_name)
745 || confess "You must define a method name";
747 return $self->{methods}{$method_name} || $self->get_method_map->{$method_name};
751 my ($self, $method_name) = @_;
752 (defined $method_name && $method_name)
753 || confess "You must define a method name";
755 my $removed_method = delete $self->get_method_map->{$method_name};
757 $self->remove_package_symbol(
758 { sigil => '&', type => 'CODE', name => $method_name }
761 $removed_method->detach_from_class if $removed_method;
763 $self->update_package_cache_flag; # still valid, since we just removed the method from the map
765 return $removed_method;
768 sub get_method_list {
770 keys %{$self->get_method_map};
773 sub find_method_by_name {
774 my ($self, $method_name) = @_;
775 (defined $method_name && $method_name)
776 || confess "You must define a method name to find";
777 foreach my $class ($self->linearized_isa) {
778 # fetch the meta-class ...
779 my $meta = $self->initialize($class);
780 return $meta->get_method($method_name)
781 if $meta->has_method($method_name);
786 sub get_all_methods {
788 my %methods = map { %{ $self->initialize($_)->get_method_map } } reverse $self->linearized_isa;
789 return values %methods;
793 sub compute_all_applicable_methods {
797 class => $_->package_name,
798 code => $_, # sigh, overloading
800 } shift->get_all_methods(@_);
803 sub find_all_methods_by_name {
804 my ($self, $method_name) = @_;
805 (defined $method_name && $method_name)
806 || confess "You must define a method name to find";
808 foreach my $class ($self->linearized_isa) {
809 # fetch the meta-class ...
810 my $meta = $self->initialize($class);
812 name => $method_name,
814 code => $meta->get_method($method_name)
815 } if $meta->has_method($method_name);
820 sub find_next_method_by_name {
821 my ($self, $method_name) = @_;
822 (defined $method_name && $method_name)
823 || confess "You must define a method name to find";
824 my @cpl = $self->linearized_isa;
825 shift @cpl; # discard ourselves
826 foreach my $class (@cpl) {
827 # fetch the meta-class ...
828 my $meta = $self->initialize($class);
829 return $meta->get_method($method_name)
830 if $meta->has_method($method_name);
839 # either we have an attribute object already
840 # or we need to create one from the args provided
841 my $attribute = blessed($_[0]) ? $_[0] : $self->attribute_metaclass->new(@_);
842 # make sure it is derived from the correct type though
843 ($attribute->isa('Class::MOP::Attribute'))
844 || confess "Your attribute must be an instance of Class::MOP::Attribute (or a subclass)";
846 # first we attach our new attribute
847 # because it might need certain information
848 # about the class which it is attached to
849 $attribute->attach_to_class($self);
851 # then we remove attributes of a conflicting
852 # name here so that we can properly detach
853 # the old attr object, and remove any
854 # accessors it would have generated
855 if ( $self->has_attribute($attribute->name) ) {
856 $self->remove_attribute($attribute->name);
858 $self->invalidate_meta_instances();
861 # then onto installing the new accessors
862 $self->get_attribute_map->{$attribute->name} = $attribute;
864 # invalidate package flag here
865 my $e = do { local $@; eval { $attribute->install_accessors() }; $@ };
867 $self->remove_attribute($attribute->name);
874 sub update_meta_instance_dependencies {
877 if ( $self->{meta_instance_dependencies} ) {
878 return $self->add_meta_instance_dependencies;
882 sub add_meta_instance_dependencies {
885 $self->remove_meta_instance_depdendencies;
887 my @attrs = $self->compute_all_applicable_attributes();
890 my @classes = grep { not $seen{$_->name}++ } map { $_->associated_class } @attrs;
892 foreach my $class ( @classes ) {
893 $class->add_dependent_meta_instance($self);
896 $self->{meta_instance_dependencies} = \@classes;
899 sub remove_meta_instance_depdendencies {
902 if ( my $classes = delete $self->{meta_instance_dependencies} ) {
903 foreach my $class ( @$classes ) {
904 $class->remove_dependent_meta_instance($self);
914 sub add_dependent_meta_instance {
915 my ( $self, $metaclass ) = @_;
916 push @{ $self->{dependent_meta_instances} }, $metaclass;
919 sub remove_dependent_meta_instance {
920 my ( $self, $metaclass ) = @_;
921 my $name = $metaclass->name;
922 @$_ = grep { $_->name ne $name } @$_ for $self->{dependent_meta_instances};
925 sub invalidate_meta_instances {
927 $_->invalidate_meta_instance() for $self, @{ $self->{dependent_meta_instances} };
930 sub invalidate_meta_instance {
932 undef $self->{_meta_instance};
936 my ($self, $attribute_name) = @_;
937 (defined $attribute_name && $attribute_name)
938 || confess "You must define an attribute name";
939 exists $self->get_attribute_map->{$attribute_name};
943 my ($self, $attribute_name) = @_;
944 (defined $attribute_name && $attribute_name)
945 || confess "You must define an attribute name";
946 return $self->get_attribute_map->{$attribute_name}
948 # this will return undef anyway, so no need ...
949 # if $self->has_attribute($attribute_name);
953 sub remove_attribute {
954 my ($self, $attribute_name) = @_;
955 (defined $attribute_name && $attribute_name)
956 || confess "You must define an attribute name";
957 my $removed_attribute = $self->get_attribute_map->{$attribute_name};
958 return unless defined $removed_attribute;
959 delete $self->get_attribute_map->{$attribute_name};
960 $self->invalidate_meta_instances();
961 $removed_attribute->remove_accessors();
962 $removed_attribute->detach_from_class();
963 return $removed_attribute;
966 sub get_attribute_list {
968 keys %{$self->get_attribute_map};
971 sub get_all_attributes {
972 shift->compute_all_applicable_attributes(@_);
975 sub compute_all_applicable_attributes {
977 my %attrs = map { %{ $self->initialize($_)->get_attribute_map } } reverse $self->linearized_isa;
978 return values %attrs;
981 sub find_attribute_by_name {
982 my ($self, $attr_name) = @_;
983 foreach my $class ($self->linearized_isa) {
984 # fetch the meta-class ...
985 my $meta = $self->initialize($class);
986 return $meta->get_attribute($attr_name)
987 if $meta->has_attribute($attr_name);
992 # check if we can reinitialize
996 # if any local attr is defined
997 return if $self->get_attribute_list;
999 # or any non-declared methods
1000 if ( my @methods = values %{ $self->get_method_map } ) {
1001 my $metaclass = $self->method_metaclass;
1002 foreach my $method ( @methods ) {
1003 return if $method->isa("Class::MOP::Method::Generated");
1004 # FIXME do we need to enforce this too? return unless $method->isa($metaclass);
1013 sub is_mutable { 1 }
1014 sub is_immutable { 0 }
1017 # Why I changed this (groditi)
1018 # - One Metaclass may have many Classes through many Metaclass instances
1019 # - One Metaclass should only have one Immutable Transformer instance
1020 # - Each Class may have different Immutabilizing options
1021 # - Therefore each Metaclass instance may have different Immutabilizing options
1022 # - We need to store one Immutable Transformer instance per Metaclass
1023 # - We need to store one set of Immutable Transformer options per Class
1024 # - Upon make_mutable we may delete the Immutabilizing options
1025 # - We could clean the immutable Transformer instance when there is no more
1026 # immutable Classes of that type, but we can also keep it in case
1027 # another class with this same Metaclass becomes immutable. It is a case
1028 # of trading of storing an instance to avoid unnecessary instantiations of
1029 # Immutable Transformers. You may view this as a memory leak, however
1030 # Because we have few Metaclasses, in practice it seems acceptable
1031 # - To allow Immutable Transformers instances to be cleaned up we could weaken
1032 # the reference stored in $IMMUTABLE_TRANSFORMERS{$class} and ||= should DWIM
1036 my %IMMUTABLE_TRANSFORMERS;
1037 my %IMMUTABLE_OPTIONS;
1039 sub get_immutable_options {
1041 return if $self->is_mutable;
1042 confess "unable to find immutabilizing options"
1043 unless exists $IMMUTABLE_OPTIONS{$self->name};
1044 my %options = %{$IMMUTABLE_OPTIONS{$self->name}};
1045 delete $options{IMMUTABLE_TRANSFORMER};
1049 sub get_immutable_transformer {
1051 if( $self->is_mutable ){
1052 return $IMMUTABLE_TRANSFORMERS{$self->name} ||= $self->create_immutable_transformer;
1054 confess "unable to find transformer for immutable class"
1055 unless exists $IMMUTABLE_OPTIONS{$self->name};
1056 return $IMMUTABLE_OPTIONS{$self->name}->{IMMUTABLE_TRANSFORMER};
1059 sub make_immutable {
1063 my $transformer = $self->get_immutable_transformer;
1064 $transformer->make_metaclass_immutable($self, \%options);
1065 $IMMUTABLE_OPTIONS{$self->name} =
1066 { %options, IMMUTABLE_TRANSFORMER => $transformer };
1068 if( exists $options{debug} && $options{debug} ){
1069 print STDERR "# of Metaclass options: ", keys %IMMUTABLE_OPTIONS;
1070 print STDERR "# of Immutable transformers: ", keys %IMMUTABLE_TRANSFORMERS;
1078 return if $self->is_mutable;
1079 my $options = delete $IMMUTABLE_OPTIONS{$self->name};
1080 confess "unable to find immutabilizing options" unless ref $options;
1081 my $transformer = delete $options->{IMMUTABLE_TRANSFORMER};
1082 $transformer->make_metaclass_mutable($self, $options);
1087 sub create_immutable_transformer {
1089 my $class = Class::MOP::Immutable->new($self, {
1090 read_only => [qw/superclasses/],
1097 remove_package_symbol
1100 class_precedence_list => 'ARRAY',
1101 linearized_isa => 'ARRAY', # FIXME perl 5.10 memoizes this on its own, no need?
1102 get_all_methods => 'ARRAY',
1103 #get_all_attributes => 'ARRAY', # it's an alias, no need, but maybe in the future
1104 compute_all_applicable_attributes => 'ARRAY',
1105 get_meta_instance => 'SCALAR',
1106 get_method_map => 'SCALAR',
1109 # this is ugly, but so are typeglobs,
1110 # so whattayahgonnadoboutit
1113 add_package_symbol => sub {
1114 my $original = shift;
1115 confess "Cannot add package symbols to an immutable metaclass"
1116 unless (caller(2))[3] eq 'Class::MOP::Package::get_package_symbol';
1118 # This is a workaround for a bug in 5.8.1 which thinks that
1119 # goto $original->body
1120 # is trying to go to a label
1121 my $body = $original->body;
1137 Class::MOP::Class - Class Meta Object
1141 # assuming that class Foo
1142 # has been defined, you can
1144 # use this for introspection ...
1146 # add a method to Foo ...
1147 Foo->meta->add_method('bar' => sub { ... })
1149 # get a list of all the classes searched
1150 # the method dispatcher in the correct order
1151 Foo->meta->class_precedence_list()
1153 # remove a method from Foo
1154 Foo->meta->remove_method('bar');
1156 # or use this to actually create classes ...
1158 Class::MOP::Class->create('Bar' => (
1160 superclasses => [ 'Foo' ],
1162 Class::MOP:::Attribute->new('$bar'),
1163 Class::MOP:::Attribute->new('$baz'),
1166 calculate_bar => sub { ... },
1167 construct_baz => sub { ... }
1173 This is the largest and currently most complex part of the Perl 5
1174 meta-object protocol. It controls the introspection and
1175 manipulation of Perl 5 classes (and it can create them too). The
1176 best way to understand what this module can do, is to read the
1177 documentation for each of it's methods.
1181 B<Class::MOP::Class> is a subclass of L<Class::MOP::Module>
1185 =head2 Self Introspection
1191 This will return a B<Class::MOP::Class> instance which is related
1192 to this class. Thereby allowing B<Class::MOP::Class> to actually
1195 As with B<Class::MOP::Attribute>, B<Class::MOP> will actually
1196 bootstrap this module by installing a number of attribute meta-objects
1197 into it's metaclass. This will allow this class to reap all the benifits
1198 of the MOP when subclassing it.
1202 =head2 Class construction
1204 These methods will handle creating B<Class::MOP::Class> objects,
1205 which can be used to both create new classes, and analyze
1206 pre-existing classes.
1208 This module will internally store references to all the instances
1209 you create with these methods, so that they do not need to be
1210 created any more than nessecary. Basically, they are singletons.
1214 =item B<create ($package_name,
1215 version =E<gt> ?$version,
1216 authority =E<gt> ?$authority,
1217 superclasses =E<gt> ?@superclasses,
1218 methods =E<gt> ?%methods,
1219 attributes =E<gt> ?%attributes)>
1221 This returns a B<Class::MOP::Class> object, bringing the specified
1222 C<$package_name> into existence and adding any of the C<$version>,
1223 C<$authority>, C<@superclasses>, C<%methods> and C<%attributes> to
1226 =item B<create_anon_class (superclasses =E<gt> ?@superclasses,
1227 methods =E<gt> ?%methods,
1228 attributes =E<gt> ?%attributes)>
1230 This will create an anonymous class, it works much like C<create> but
1231 it does not need a C<$package_name>. Instead it will create a suitably
1232 unique package name for you to stash things into.
1234 On very important distinction is that anon classes are destroyed once
1235 the metaclass they are attached to goes out of scope. In the DESTROY
1236 method, the created package will be removed from the symbol table.
1238 It is also worth noting that any instances created with an anon-class
1239 will keep a special reference to the anon-meta which will prevent the
1240 anon-class from going out of scope until all instances of it have also
1241 been destroyed. This however only works for HASH based instance types,
1242 as we use a special reserved slot (C<__MOP__>) to store this.
1244 =item B<initialize ($package_name, %options)>
1246 This initializes and returns returns a B<Class::MOP::Class> object
1247 for a given a C<$package_name>.
1249 =item B<construct_class_instance (%options)>
1251 This will construct an instance of B<Class::MOP::Class>, it is
1252 here so that we can actually "tie the knot" for B<Class::MOP::Class>
1253 to use C<construct_instance> once all the bootstrapping is done. This
1254 method is used internally by C<initialize> and should never be called
1255 from outside of that method really.
1257 =item B<check_metaclass_compatibility>
1259 This method is called as the very last thing in the
1260 C<construct_class_instance> method. This will check that the
1261 metaclass you are creating is compatible with the metaclasses of all
1262 your ancestors. For more inforamtion about metaclass compatibility
1263 see the C<About Metaclass compatibility> section in L<Class::MOP>.
1265 =item B<update_package_cache_flag>
1267 This will reset the package cache flag for this particular metaclass
1268 it is basically the value of the C<Class::MOP::get_package_cache_flag>
1269 function. This is very rarely needed from outside of C<Class::MOP::Class>
1270 but in some cases you might want to use it, so it is here.
1272 =item B<reset_package_cache_flag>
1274 Clears the package cache flag to announce to the internals that we need
1275 to rebuild the method map.
1277 =item B<add_meta_instance_dependencies>
1279 Registers this class as dependent on its superclasses.
1281 Only superclasses from which this class inherits attributes will be added.
1283 =item B<remove_meta_instance_depdendencies>
1285 Unregisters this class from its superclasses.
1287 =item B<update_meta_instance_dependencies>
1289 Reregisters if necessary.
1291 =item B<add_dependent_meta_instance> $metaclass
1293 Registers the class as having a meta instance dependent on this class.
1295 =item B<remove_dependent_meta_instance> $metaclass
1297 Remove the class from the list of dependent classes.
1299 =item B<invalidate_meta_instances>
1301 Clears the cached meta instance for this metaclass and all of the registered
1302 classes with dependent meta instances.
1304 Called by C<add_attribute> and C<remove_attribute> to recalculate the attribute
1307 =item B<invalidate_meta_instance>
1309 Used by C<invalidate_meta_instances>.
1313 =head2 Object instance construction and cloning
1315 These methods are B<entirely optional>, it is up to you whether you want
1320 =item B<instance_metaclass>
1322 Returns the class name of the instance metaclass, see L<Class::MOP::Instance>
1323 for more information on the instance metaclasses.
1325 =item B<get_meta_instance>
1327 Returns an instance of L<Class::MOP::Instance> to be used in the construction
1328 of a new instance of the class.
1330 =item B<create_meta_instance>
1332 Called by C<get_meta_instance> if necessary.
1334 =item B<new_object (%params)>
1336 This is a convience method for creating a new object of the class, and
1337 blessing it into the appropriate package as well. Ideally your class
1338 would call a C<new> this method like so:
1341 my ($class, %param) = @_;
1342 $class->meta->new_object(%params);
1345 =item B<construct_instance (%params)>
1347 This method is used to construct an instance structure suitable for
1348 C<bless>-ing into your package of choice. It works in conjunction
1349 with the Attribute protocol to collect all applicable attributes.
1351 This will construct an instance using a HASH ref as storage
1352 (currently only HASH references are supported). This will collect all
1353 the applicable attributes and layout out the fields in the HASH ref,
1354 it will then initialize them using either use the corresponding key
1355 in C<%params> or any default value or initializer found in the
1356 attribute meta-object.
1358 =item B<clone_object ($instance, %params)>
1360 This is a convience method for cloning an object instance, then
1361 blessing it into the appropriate package. This method will call
1362 C<clone_instance>, which performs a shallow copy of the object,
1363 see that methods documentation for more details. Ideally your
1364 class would call a C<clone> this method like so:
1366 sub MyClass::clone {
1367 my ($self, %param) = @_;
1368 $self->meta->clone_object($self, %params);
1371 =item B<clone_instance($instance, %params)>
1373 This method is a compliment of C<construct_instance> (which means if
1374 you override C<construct_instance>, you need to override this one too),
1375 and clones the instance shallowly.
1377 The cloned structure returned is (like with C<construct_instance>) an
1378 unC<bless>ed HASH reference, it is your responsibility to then bless
1379 this cloned structure into the right class (which C<clone_object> will
1382 As of 0.11, this method will clone the C<$instance> structure shallowly,
1383 as opposed to the deep cloning implemented in prior versions. After much
1384 thought, research and discussion, I have decided that anything but basic
1385 shallow cloning is outside the scope of the meta-object protocol. I
1386 think Yuval "nothingmuch" Kogman put it best when he said that cloning
1387 is too I<context-specific> to be part of the MOP.
1389 =item B<rebless_instance($instance, ?%params)>
1391 This will change the class of C<$instance> to the class of the invoking
1392 C<Class::MOP::Class>. You may only rebless the instance to a subclass of
1393 itself. You may pass in optional C<%params> which are like constructor
1394 params and will override anything already defined in the instance.
1398 =head2 Informational
1400 These are a few predicate methods for asking information about the class.
1404 =item B<is_anon_class>
1406 This returns true if the class is a C<Class::MOP::Class> created anon class.
1410 This returns true if the class is still mutable.
1412 =item B<is_immutable>
1414 This returns true if the class has been made immutable.
1416 =item B<is_pristine>
1418 Checks whether the class has any data that will be lost if C<reinitialize> is
1423 =head2 Inheritance Relationships
1427 =item B<superclasses (?@superclasses)>
1429 This is a read-write attribute which represents the superclass
1430 relationships of the class the B<Class::MOP::Class> instance is
1431 associated with. Basically, it can get and set the C<@ISA> for you.
1433 =item B<class_precedence_list>
1435 This computes the a list of all the class's ancestors in the same order
1436 in which method dispatch will be done. This is similair to what
1437 B<Class::ISA::super_path> does, but we don't remove duplicate names.
1439 =item B<linearized_isa>
1441 This returns a list based on C<class_precedence_list> but with all
1446 This returns a list of subclasses for this class.
1454 =item B<get_method_map>
1456 Returns a HASH ref of name to CODE reference mapping for this class.
1458 =item B<method_metaclass>
1460 Returns the class name of the method metaclass, see L<Class::MOP::Method>
1461 for more information on the method metaclasses.
1463 =item B<wrap_method_body(%attrs)>
1465 Wrap a code ref (C<$attrs{body>) with C<method_metaclass>.
1467 =item B<add_method ($method_name, $method)>
1469 This will take a C<$method_name> and CODE reference or meta method
1470 objectand install it into the class's package.
1472 You are strongly encouraged to pass a meta method object instead of a
1473 code reference. If you do so, that object gets stored as part of the
1474 class's method map, providing more useful information about the method
1477 When you provide a method object, this method will clone that object
1478 if the object's package name does not match the class name. This lets
1479 us track the original source of any methods added from other classes
1480 (notably Moose roles).
1483 This does absolutely nothing special to C<$method>
1484 other than use B<Sub::Name> to make sure it is tagged with the
1485 correct name, and therefore show up correctly in stack traces and
1488 =item B<has_method ($method_name)>
1490 This just provides a simple way to check if the class implements
1491 a specific C<$method_name>. It will I<not> however, attempt to check
1492 if the class inherits the method (use C<UNIVERSAL::can> for that).
1494 This will correctly handle functions defined outside of the package
1495 that use a fully qualified name (C<sub Package::name { ... }>).
1497 This will correctly handle functions renamed with B<Sub::Name> and
1498 installed using the symbol tables. However, if you are naming the
1499 subroutine outside of the package scope, you must use the fully
1500 qualified name, including the package name, for C<has_method> to
1501 correctly identify it.
1503 This will attempt to correctly ignore functions imported from other
1504 packages using B<Exporter>. It breaks down if the function imported
1505 is an C<__ANON__> sub (such as with C<use constant>), which very well
1506 may be a valid method being applied to the class.
1508 In short, this method cannot always be trusted to determine if the
1509 C<$method_name> is actually a method. However, it will DWIM about
1510 90% of the time, so it's a small trade off I think.
1512 =item B<get_method ($method_name)>
1514 This will return a Class::MOP::Method instance related to the specified
1515 C<$method_name>, or return undef if that method does not exist.
1517 The Class::MOP::Method is codifiable, so you can use it like a normal
1518 CODE reference, see L<Class::MOP::Method> for more information.
1520 =item B<find_method_by_name ($method_name)>
1522 This will return a CODE reference of the specified C<$method_name>,
1523 or return undef if that method does not exist.
1525 Unlike C<get_method> this will also look in the superclasses.
1527 =item B<remove_method ($method_name)>
1529 This will attempt to remove a given C<$method_name> from the class.
1530 It will return the CODE reference that it has removed, and will
1531 attempt to use B<Sub::Name> to clear the methods associated name.
1533 =item B<get_method_list>
1535 This will return a list of method names for all I<locally> defined
1536 methods. It does B<not> provide a list of all applicable methods,
1537 including any inherited ones. If you want a list of all applicable
1538 methods, use the C<compute_all_applicable_methods> method.
1540 =item B<get_all_methods>
1542 This will traverse the inheritance heirachy and return a list of all
1543 the applicable L<Class::MOP::Method> objects for this class.
1545 =item B<compute_all_applicable_methods>
1549 This method returns a list of hashes describing the all the methods of the
1552 Use L<get_all_methods>, which is easier/better/faster. This method predates
1553 L<Class::MOP::Method>.
1555 =item B<find_all_methods_by_name ($method_name)>
1557 This will traverse the inheritence hierarchy and locate all methods
1558 with a given C<$method_name>. Similar to
1559 C<compute_all_applicable_methods> it returns a list of HASH references
1560 with the following information; method name (which will always be the
1561 same as C<$method_name>), the name of the class in which the method
1562 lives and a CODE reference for the actual method.
1564 The list of methods produced is a distinct list, meaning there are no
1565 duplicates in it. This is especially useful for things like object
1566 initialization and destruction where you only want the method called
1567 once, and in the correct order.
1569 =item B<find_next_method_by_name ($method_name)>
1571 This will return the first method to match a given C<$method_name> in
1572 the superclasses, this is basically equivalent to calling
1573 C<SUPER::$method_name>, but it can be dispatched at runtime.
1575 =item B<alias_method ($method_name, $method)>
1577 B<NOTE>: This method is now deprecated. Just use C<add_method>
1582 =head2 Method Modifiers
1584 Method modifiers are a concept borrowed from CLOS, in which a method
1585 can be wrapped with I<before>, I<after> and I<around> method modifiers
1586 that will be called everytime the method is called.
1588 =head3 How method modifiers work?
1590 Method modifiers work by wrapping the original method and then replacing
1591 it in the classes symbol table. The wrappers will handle calling all the
1592 modifiers in the appropariate orders and preserving the calling context
1593 for the original method.
1595 Each method modifier serves a particular purpose, which may not be
1596 obvious to users of other method wrapping modules. To start with, the
1597 return values of I<before> and I<after> modifiers are ignored. This is
1598 because thier purpose is B<not> to filter the input and output of the
1599 primary method (this is done with an I<around> modifier). This may seem
1600 like an odd restriction to some, but doing this allows for simple code
1601 to be added at the begining or end of a method call without jeapordizing
1602 the normal functioning of the primary method or placing any extra
1603 responsibility on the code of the modifier. Of course if you have more
1604 complex needs, then use the I<around> modifier, which uses a variation
1605 of continutation passing style to allow for a high degree of flexibility.
1607 Before and around modifiers are called in last-defined-first-called order,
1608 while after modifiers are called in first-defined-first-called order. So
1609 the call tree might looks something like this:
1621 To see examples of using method modifiers, see the following examples
1622 included in the distribution; F<InstanceCountingClass>, F<Perl6Attribute>,
1623 F<AttributesWithHistory> and F<C3MethodDispatchOrder>. There is also a
1624 classic CLOS usage example in the test F<017_add_method_modifier.t>.
1626 =head3 What is the performance impact?
1628 Of course there is a performance cost associated with method modifiers,
1629 but we have made every effort to make that cost be directly proportional
1630 to the amount of modifier features you utilize.
1632 The wrapping method does it's best to B<only> do as much work as it
1633 absolutely needs to. In order to do this we have moved some of the
1634 performance costs to set-up time, where they are easier to amortize.
1636 All this said, my benchmarks have indicated the following:
1638 simple wrapper with no modifiers 100% slower
1639 simple wrapper with simple before modifier 400% slower
1640 simple wrapper with simple after modifier 450% slower
1641 simple wrapper with simple around modifier 500-550% slower
1642 simple wrapper with all 3 modifiers 1100% slower
1644 These numbers may seem daunting, but you must remember, every feature
1645 comes with some cost. To put things in perspective, just doing a simple
1646 C<AUTOLOAD> which does nothing but extract the name of the method called
1647 and return it costs about 400% over a normal method call.
1651 =item B<add_before_method_modifier ($method_name, $code)>
1653 This will wrap the method at C<$method_name> and the supplied C<$code>
1654 will be passed the C<@_> arguments, and called before the original
1655 method is called. As specified above, the return value of the I<before>
1656 method modifiers is ignored, and it's ability to modify C<@_> is
1657 fairly limited. If you need to do either of these things, use an
1658 C<around> method modifier.
1660 =item B<add_after_method_modifier ($method_name, $code)>
1662 This will wrap the method at C<$method_name> so that the original
1663 method will be called, it's return values stashed, and then the
1664 supplied C<$code> will be passed the C<@_> arguments, and called.
1665 As specified above, the return value of the I<after> method
1666 modifiers is ignored, and it cannot modify the return values of
1667 the original method. If you need to do either of these things, use an
1668 C<around> method modifier.
1670 =item B<add_around_method_modifier ($method_name, $code)>
1672 This will wrap the method at C<$method_name> so that C<$code>
1673 will be called and passed the original method as an extra argument
1674 at the begining of the C<@_> argument list. This is a variation of
1675 continuation passing style, where the function prepended to C<@_>
1676 can be considered a continuation. It is up to C<$code> if it calls
1677 the original method or not, there is no restriction on what the
1678 C<$code> can or cannot do.
1684 It should be noted that since there is no one consistent way to define
1685 the attributes of a class in Perl 5. These methods can only work with
1686 the information given, and can not easily discover information on
1687 their own. See L<Class::MOP::Attribute> for more details.
1691 =item B<attribute_metaclass>
1693 Returns the class name of the attribute metaclass, see L<Class::MOP::Attribute>
1694 for more information on the attribute metaclasses.
1696 =item B<get_attribute_map>
1698 This returns a HASH ref of name to attribute meta-object mapping.
1700 =item B<add_attribute ($attribute_meta_object | ($attribute_name, %attribute_spec))>
1702 This stores the C<$attribute_meta_object> (or creates one from the
1703 C<$attribute_name> and C<%attribute_spec>) in the B<Class::MOP::Class>
1704 instance associated with the given class. Unlike methods, attributes
1705 within the MOP are stored as meta-information only. They will be used
1706 later to construct instances from (see C<construct_instance> above).
1707 More details about the attribute meta-objects can be found in the
1708 L<Class::MOP::Attribute> or the L<Class::MOP/The Attribute protocol>
1711 It should be noted that any accessor, reader/writer or predicate
1712 methods which the C<$attribute_meta_object> has will be installed
1713 into the class at this time.
1716 If an attribute already exists for C<$attribute_name>, the old one
1717 will be removed (as well as removing all it's accessors), and then
1720 =item B<has_attribute ($attribute_name)>
1722 Checks to see if this class has an attribute by the name of
1723 C<$attribute_name> and returns a boolean.
1725 =item B<get_attribute ($attribute_name)>
1727 Returns the attribute meta-object associated with C<$attribute_name>,
1728 if none is found, it will return undef.
1730 =item B<remove_attribute ($attribute_name)>
1732 This will remove the attribute meta-object stored at
1733 C<$attribute_name>, then return the removed attribute meta-object.
1736 Removing an attribute will only affect future instances of
1737 the class, it will not make any attempt to remove the attribute from
1738 any existing instances of the class.
1740 It should be noted that any accessor, reader/writer or predicate
1741 methods which the attribute meta-object stored at C<$attribute_name>
1742 has will be removed from the class at this time. This B<will> make
1743 these attributes somewhat inaccessable in previously created
1744 instances. But if you are crazy enough to do this at runtime, then
1745 you are crazy enough to deal with something like this :).
1747 =item B<get_attribute_list>
1749 This returns a list of attribute names which are defined in the local
1750 class. If you want a list of all applicable attributes for a class,
1751 use the C<compute_all_applicable_attributes> method.
1753 =item B<compute_all_applicable_attributes>
1755 =item B<get_all_attributes>
1757 This will traverse the inheritance heirachy and return a list of all
1758 the applicable L<Class::MOP::Attribute> objects for this class.
1760 C<get_all_attributes> is an alias for consistency with C<get_all_methods>.
1762 =item B<find_attribute_by_name ($attr_name)>
1764 This method will traverse the inheritance heirachy and find the
1765 first attribute whose name matches C<$attr_name>, then return it.
1766 It will return undef if nothing is found.
1770 =head2 Class Immutability
1774 =item B<make_immutable (%options)>
1776 This method will invoke a tranforamtion upon the class which will
1777 make it immutable. Details of this transformation can be found in
1778 the L<Class::MOP::Immutable> documentation.
1780 =item B<make_mutable>
1782 This method will reverse tranforamtion upon the class which
1785 =item B<get_immutable_transformer>
1787 Return a transformer suitable for making this class immutable or, if this
1788 class is immutable, the transformer used to make it immutable.
1790 =item B<get_immutable_options>
1792 If the class is immutable, return the options used to make it immutable.
1794 =item B<create_immutable_transformer>
1796 Create a transformer suitable for making this class immutable
1802 Stevan Little E<lt>stevan@iinteractive.comE<gt>
1804 =head1 COPYRIGHT AND LICENSE
1806 Copyright 2006-2008 by Infinity Interactive, Inc.
1808 L<http://www.iinteractive.com>
1810 This library is free software; you can redistribute it and/or modify
1811 it under the same terms as Perl itself.