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 = '0.65';
15 our $AUTHORITY = 'cpan:STEVAN';
17 use base 'Class::MOP::Module';
27 $package_name = shift;
30 $package_name = $options{package};
33 (defined $package_name && $package_name && !ref($package_name))
34 || confess "You must pass a package name and it cannot be blessed";
36 return Class::MOP::get_metaclass_by_name($package_name)
37 || $class->construct_class_instance(package => $package_name, @_);
42 my $package_name = shift;
43 (defined $package_name && $package_name && !blessed($package_name))
44 || confess "You must pass a package name and it cannot be blessed";
45 Class::MOP::remove_metaclass_by_name($package_name);
46 $class->construct_class_instance('package' => $package_name, @_);
49 # NOTE: (meta-circularity)
50 # this is a special form of &construct_instance
51 # (see below), which is used to construct class
52 # meta-object instances for any Class::MOP::*
53 # class. All other classes will use the more
54 # normal &construct_instance.
55 sub construct_class_instance {
58 my $package_name = $options{'package'};
59 (defined $package_name && $package_name)
60 || confess "You must pass a package name";
62 # return the metaclass if we have it cached,
63 # and it is still defined (it has not been
64 # reaped by DESTROY yet, which can happen
65 # annoyingly enough during global destruction)
67 if (defined(my $meta = Class::MOP::get_metaclass_by_name($package_name))) {
72 # we need to deal with the possibility
73 # of class immutability here, and then
74 # get the name of the class appropriately
75 $class = (blessed($class)
76 ? ($class->is_immutable
77 ? $class->get_mutable_metaclass_name()
81 # now create the metaclass
83 if ($class eq 'Class::MOP::Class') {
86 # inherited from Class::MOP::Package
87 'package' => $package_name,
90 # since the following attributes will
91 # actually be loaded from the symbol
92 # table, and actually bypass the instance
93 # entirely, we can just leave these things
94 # listed here for reference, because they
95 # should not actually have a value associated
97 'namespace' => \undef,
98 # inherited from Class::MOP::Module
100 'authority' => \undef,
101 # defined in Class::MOP::Class
102 'superclasses' => \undef,
106 'attribute_metaclass' => $options{'attribute_metaclass'} || 'Class::MOP::Attribute',
107 'method_metaclass' => $options{'method_metaclass'} || 'Class::MOP::Method',
108 'instance_metaclass' => $options{'instance_metaclass'} || 'Class::MOP::Instance',
110 ## uber-private variables
112 # this starts out as undef so that
113 # we can tell the first time the
114 # methods are fetched
116 '_package_cache_flag' => undef,
117 '_meta_instance' => undef,
122 # it is safe to use meta here because
123 # class will always be a subclass of
124 # Class::MOP::Class, which defines meta
125 $meta = $class->meta->construct_instance(%options)
128 # and check the metaclass compatibility
129 $meta->check_metaclass_compatability();
131 Class::MOP::store_metaclass_by_name($package_name, $meta);
134 # we need to weaken any anon classes
135 # so that they can call DESTROY properly
136 Class::MOP::weaken_metaclass($package_name) if $meta->is_anon_class;
141 sub reset_package_cache_flag { (shift)->{'_package_cache_flag'} = undef }
142 sub update_package_cache_flag {
145 # we can manually update the cache number
146 # since we are actually adding the method
147 # to our cache as well. This avoids us
148 # having to regenerate the method_map.
150 $self->{'_package_cache_flag'} = Class::MOP::check_package_cache_flag($self->name);
153 sub check_metaclass_compatability {
156 # this is always okay ...
157 return if blessed($self) eq 'Class::MOP::Class' &&
158 $self->instance_metaclass eq 'Class::MOP::Instance';
160 my @class_list = $self->linearized_isa;
161 shift @class_list; # shift off $self->name
163 foreach my $class_name (@class_list) {
164 my $meta = Class::MOP::get_metaclass_by_name($class_name) || next;
167 # we need to deal with the possibility
168 # of class immutability here, and then
169 # get the name of the class appropriately
170 my $meta_type = ($meta->is_immutable
171 ? $meta->get_mutable_metaclass_name()
174 ($self->isa($meta_type))
175 || confess $self->name . "->meta => (" . (blessed($self)) . ")" .
176 " is not compatible with the " .
177 $class_name . "->meta => (" . ($meta_type) . ")";
179 # we also need to check that instance metaclasses
180 # are compatabile in the same the class.
181 ($self->instance_metaclass->isa($meta->instance_metaclass))
182 || confess $self->name . "->meta => (" . ($self->instance_metaclass) . ")" .
183 " is not compatible with the " .
184 $class_name . "->meta => (" . ($meta->instance_metaclass) . ")";
192 # this should be sufficient, if you have a
193 # use case where it is not, write a test and
195 my $ANON_CLASS_SERIAL = 0;
198 # we need a sufficiently annoying prefix
199 # this should suffice for now, this is
200 # used in a couple of places below, so
201 # need to put it up here for now.
202 my $ANON_CLASS_PREFIX = 'Class::MOP::Class::__ANON__::SERIAL::';
206 no warnings 'uninitialized';
207 $self->name =~ /^$ANON_CLASS_PREFIX/ ? 1 : 0;
210 sub create_anon_class {
211 my ($class, %options) = @_;
212 my $package_name = $ANON_CLASS_PREFIX . ++$ANON_CLASS_SERIAL;
213 return $class->create($package_name, %options);
219 require Devel::GlobalDestruction;
220 Devel::GlobalDestruction->import("in_global_destruction");
222 } or *in_global_destruction = sub () { '' };
226 # this will only get called for
227 # anon-classes, all other calls
228 # are assumed to occur during
229 # global destruction and so don't
230 # really need to be handled explicitly
234 return if in_global_destruction; # it'll happen soon anyway and this just makes things more complicated
236 no warnings 'uninitialized';
237 return unless $self->name =~ /^$ANON_CLASS_PREFIX/;
238 my ($serial_id) = ($self->name =~ /^$ANON_CLASS_PREFIX(\d+)/);
240 foreach my $key (keys %{$ANON_CLASS_PREFIX . $serial_id}) {
241 delete ${$ANON_CLASS_PREFIX . $serial_id}{$key};
243 delete ${'main::' . $ANON_CLASS_PREFIX}{$serial_id . '::'};
248 # creating classes with MOP ...
251 my ( $class, @args ) = @_;
253 unshift @args, 'package' if @args % 2 == 1;
255 my (%options) = @args;
256 my $package_name = $options{package};
258 (defined $package_name && $package_name)
259 || confess "You must pass a package name";
261 (ref $options{superclasses} eq 'ARRAY')
262 || confess "You must pass an ARRAY ref of superclasses"
263 if exists $options{superclasses};
265 (ref $options{attributes} eq 'ARRAY')
266 || confess "You must pass an ARRAY ref of attributes"
267 if exists $options{attributes};
269 (ref $options{methods} eq 'HASH')
270 || confess "You must pass an HASH ref of methods"
271 if exists $options{methods};
273 my $code = "package $package_name;";
274 $code .= "\$$package_name\:\:VERSION = '" . $options{version} . "';"
275 if exists $options{version};
276 $code .= "\$$package_name\:\:AUTHORITY = '" . $options{authority} . "';"
277 if exists $options{authority};
280 confess "creation of $package_name failed : $@" if $@;
282 my $meta = $class->initialize($package_name);
285 $meta->add_method('meta' => sub {
286 $class->initialize(blessed($_[0]) || $_[0]);
289 $meta->superclasses(@{$options{superclasses}})
290 if exists $options{superclasses};
292 # process attributes first, so that they can
293 # install accessors, but locally defined methods
294 # can then overwrite them. It is maybe a little odd, but
295 # I think this should be the order of things.
296 if (exists $options{attributes}) {
297 foreach my $attr (@{$options{attributes}}) {
298 $meta->add_attribute($attr);
301 if (exists $options{methods}) {
302 foreach my $method_name (keys %{$options{methods}}) {
303 $meta->add_method($method_name, $options{methods}->{$method_name});
312 # all these attribute readers will be bootstrapped
313 # away in the Class::MOP bootstrap section
315 sub get_attribute_map { $_[0]->{'attributes'} }
316 sub attribute_metaclass { $_[0]->{'attribute_metaclass'} }
317 sub method_metaclass { $_[0]->{'method_metaclass'} }
318 sub instance_metaclass { $_[0]->{'instance_metaclass'} }
321 # this is a prime canidate for conversion to XS
325 my $current = Class::MOP::check_package_cache_flag($self->name);
327 if (defined $self->{'_package_cache_flag'} && $self->{'_package_cache_flag'} == $current) {
328 return $self->{'methods'};
331 $self->{_package_cache_flag} = $current;
333 my $map = $self->{'methods'};
335 my $class_name = $self->name;
336 my $method_metaclass = $self->method_metaclass;
338 my %all_code = $self->get_all_package_symbols('CODE');
340 foreach my $symbol (keys %all_code) {
341 my $code = $all_code{$symbol};
343 next if exists $map->{$symbol} &&
344 defined $map->{$symbol} &&
345 $map->{$symbol}->body == $code;
347 my ($pkg, $name) = Class::MOP::get_code_info($code);
350 # in 5.10 constant.pm the constants show up
351 # as being in the right package, but in pre-5.10
352 # they show up as constant::__ANON__ so we
353 # make an exception here to be sure that things
354 # work as expected in both.
356 unless ($pkg eq 'constant' && $name eq '__ANON__') {
357 next if ($pkg || '') ne $class_name ||
358 (($name || '') ne '__ANON__' && ($pkg || '') ne $class_name);
361 $map->{$symbol} = $method_metaclass->wrap(
363 package_name => $class_name,
371 # Instance Construction & Cloning
377 # we need to protect the integrity of the
378 # Class::MOP::Class singletons here, so we
379 # delegate this to &construct_class_instance
380 # which will deal with the singletons
381 return $class->construct_class_instance(@_)
382 if $class->name->isa('Class::MOP::Class');
383 return $class->construct_instance(@_);
386 sub construct_instance {
387 my ($class, %params) = @_;
388 my $meta_instance = $class->get_meta_instance();
389 my $instance = $meta_instance->create_instance();
390 foreach my $attr ($class->compute_all_applicable_attributes()) {
391 $attr->initialize_instance_slot($meta_instance, $instance, \%params);
394 # this will only work for a HASH instance type
395 if ($class->is_anon_class) {
396 (Scalar::Util::reftype($instance) eq 'HASH')
397 || confess "Currently only HASH based instances are supported with instance of anon-classes";
399 # At some point we should make this official
400 # as a reserved slot name, but right now I am
401 # going to keep it here.
402 # my $RESERVED_MOP_SLOT = '__MOP__';
403 $instance->{'__MOP__'} = $class;
409 sub get_meta_instance {
411 $self->{'_meta_instance'} ||= $self->create_meta_instance();
414 sub create_meta_instance {
417 my $instance = $self->instance_metaclass->new(
418 associated_metaclass => $self,
419 attributes => [ $self->compute_all_applicable_attributes() ],
422 $self->add_meta_instance_dependencies()
423 if $instance->is_dependent_on_superclasses();
430 my $instance = shift;
431 (blessed($instance) && $instance->isa($class->name))
432 || confess "You must pass an instance of the metaclass (" . $class->name . "), not ($instance)";
435 # we need to protect the integrity of the
436 # Class::MOP::Class singletons here, they
437 # should not be cloned.
438 return $instance if $instance->isa('Class::MOP::Class');
439 $class->clone_instance($instance, @_);
443 my ($class, $instance, %params) = @_;
445 || confess "You can only clone instances, ($instance) is not a blessed instance";
446 my $meta_instance = $class->get_meta_instance();
447 my $clone = $meta_instance->clone_instance($instance);
448 foreach my $attr ($class->compute_all_applicable_attributes()) {
449 if ( defined( my $init_arg = $attr->init_arg ) ) {
450 if (exists $params{$init_arg}) {
451 $attr->set_value($clone, $params{$init_arg});
458 sub rebless_instance {
459 my ($self, $instance, %params) = @_;
462 if ($instance->can('meta')) {
463 ($instance->meta->isa('Class::MOP::Class'))
464 || confess 'Cannot rebless instance if ->meta is not an instance of Class::MOP::Class';
465 $old_metaclass = $instance->meta;
468 $old_metaclass = $self->initialize(blessed($instance));
471 my $meta_instance = $self->get_meta_instance();
473 $self->name->isa($old_metaclass->name)
474 || confess "You may rebless only into a subclass of (". $old_metaclass->name ."), of which (". $self->name .") isn't.";
477 $meta_instance->rebless_instance_structure($instance, $self);
479 foreach my $attr ( $self->compute_all_applicable_attributes ) {
480 if ( $attr->has_value($instance) ) {
481 if ( defined( my $init_arg = $attr->init_arg ) ) {
482 $params{$init_arg} = $attr->get_value($instance)
483 unless exists $params{$init_arg};
486 $attr->set_value($instance, $attr->get_value($instance));
491 foreach my $attr ($self->compute_all_applicable_attributes) {
492 $attr->initialize_instance_slot($meta_instance, $instance, \%params);
502 my $var_spec = { sigil => '@', type => 'ARRAY', name => 'ISA' };
505 @{$self->get_package_symbol($var_spec)} = @supers;
507 # we need to check the metaclass
508 # compatibility here so that we can
509 # be sure that the superclass is
510 # not potentially creating an issues
511 # we don't know about
512 $self->check_metaclass_compatability();
513 $self->update_meta_instance_dependencies();
515 @{$self->get_package_symbol($var_spec)};
521 my $super_class = $self->name;
523 if ( Class::MOP::HAVE_ISAREV() ) {
524 return @{ $super_class->mro::get_isarev() };
528 my $find_derived_classes;
529 $find_derived_classes = sub {
530 my ($outer_class) = @_;
532 my $symbol_table_hashref = do { no strict 'refs'; \%{"${outer_class}::"} };
535 for my $symbol ( keys %$symbol_table_hashref ) {
536 next SYMBOL if $symbol !~ /\A (\w+):: \z/x;
537 my $inner_class = $1;
539 next SYMBOL if $inner_class eq 'SUPER'; # skip '*::SUPER'
543 ? "${outer_class}::$inner_class"
546 if ( $class->isa($super_class) and $class ne $super_class ) {
547 push @derived_classes, $class;
550 next SYMBOL if $class eq 'main'; # skip 'main::*'
552 $find_derived_classes->($class);
556 my $root_class = q{};
557 $find_derived_classes->($root_class);
559 undef $find_derived_classes;
561 @derived_classes = sort { $a->isa($b) ? 1 : $b->isa($a) ? -1 : 0 } @derived_classes;
563 return @derived_classes;
569 return @{ mro::get_linear_isa( (shift)->name ) };
572 sub class_precedence_list {
574 my $name = $self->name;
576 unless (Class::MOP::IS_RUNNING_ON_5_10()) {
578 # We need to check for circular inheritance here
579 # if we are are not on 5.10, cause 5.8 detects it
580 # late. This will do nothing if all is well, and
581 # blow up otherwise. Yes, it's an ugly hack, better
582 # suggestions are welcome.
584 ($name || return)->isa('This is a test for circular inheritance')
587 # if our mro is c3, we can
588 # just grab the linear_isa
589 if (mro::get_mro($name) eq 'c3') {
590 return @{ mro::get_linear_isa($name) }
594 # we can't grab the linear_isa for dfs
595 # since it has all the duplicates
600 $self->initialize($_)->class_precedence_list()
601 } $self->superclasses()
609 my ($self, $method_name, $method) = @_;
610 (defined $method_name && $method_name)
611 || confess "You must define a method name";
614 if (blessed($method)) {
615 $body = $method->body;
616 if ($method->package_name ne $self->name &&
617 $method->name ne $method_name) {
618 warn "Hello there, got something for you."
619 . " Method says " . $method->package_name . " " . $method->name
620 . " Class says " . $self->name . " " . $method_name;
621 $method = $method->clone(
622 package_name => $self->name,
624 ) if $method->can('clone');
629 ('CODE' eq ref($body))
630 || confess "Your code block must be a CODE reference";
631 $method = $self->method_metaclass->wrap(
633 package_name => $self->name,
638 $self->get_method_map->{$method_name} = $method;
640 my $full_method_name = ($self->name . '::' . $method_name);
641 $self->add_package_symbol(
642 { sigil => '&', type => 'CODE', name => $method_name },
643 Class::MOP::subname($full_method_name => $body)
646 $self->update_package_cache_flag; # still valid, since we just added the method to the map, and if it was invalid before that then get_method_map updated it
650 my $fetch_and_prepare_method = sub {
651 my ($self, $method_name) = @_;
653 my $method = $self->get_method($method_name);
654 # if we dont have local ...
656 # try to find the next method
657 $method = $self->find_next_method_by_name($method_name);
658 # die if it does not exist
660 || confess "The method '$method_name' is not found in the inheritance hierarchy for class " . $self->name;
661 # and now make sure to wrap it
662 # even if it is already wrapped
663 # because we need a new sub ref
664 $method = Class::MOP::Method::Wrapped->wrap($method);
667 # now make sure we wrap it properly
668 $method = Class::MOP::Method::Wrapped->wrap($method)
669 unless $method->isa('Class::MOP::Method::Wrapped');
671 $self->add_method($method_name => $method);
675 sub add_before_method_modifier {
676 my ($self, $method_name, $method_modifier) = @_;
677 (defined $method_name && $method_name)
678 || confess "You must pass in a method name";
679 my $method = $fetch_and_prepare_method->($self, $method_name);
680 $method->add_before_modifier(
681 Class::MOP::subname(':before' => $method_modifier)
685 sub add_after_method_modifier {
686 my ($self, $method_name, $method_modifier) = @_;
687 (defined $method_name && $method_name)
688 || confess "You must pass in a method name";
689 my $method = $fetch_and_prepare_method->($self, $method_name);
690 $method->add_after_modifier(
691 Class::MOP::subname(':after' => $method_modifier)
695 sub add_around_method_modifier {
696 my ($self, $method_name, $method_modifier) = @_;
697 (defined $method_name && $method_name)
698 || confess "You must pass in a method name";
699 my $method = $fetch_and_prepare_method->($self, $method_name);
700 $method->add_around_modifier(
701 Class::MOP::subname(':around' => $method_modifier)
706 # the methods above used to be named like this:
707 # ${pkg}::${method}:(before|after|around)
708 # but this proved problematic when using one modifier
709 # to wrap multiple methods (something which is likely
710 # to happen pretty regularly IMO). So instead of naming
711 # it like this, I have chosen to just name them purely
712 # with their modifier names, like so:
713 # :(before|after|around)
714 # The fact is that in a stack trace, it will be fairly
715 # evident from the context what method they are attached
716 # to, and so don't need the fully qualified name.
720 my ($self, $method_name, $method) = @_;
721 (defined $method_name && $method_name)
722 || confess "You must define a method name";
724 my $body = (blessed($method) ? $method->body : $method);
725 ('CODE' eq ref($body))
726 || confess "Your code block must be a CODE reference";
728 $self->add_package_symbol(
729 { sigil => '&', type => 'CODE', name => $method_name } => $body
734 my ($self, $method_name) = @_;
735 (defined $method_name && $method_name)
736 || confess "You must define a method name";
738 return 0 unless 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";
748 # I don't really need this here, because
749 # if the method_map is missing a key it
750 # will just return undef for me now
751 # return unless $self->has_method($method_name);
753 return $self->get_method_map->{$method_name};
757 my ($self, $method_name) = @_;
758 (defined $method_name && $method_name)
759 || confess "You must define a method name";
761 my $removed_method = delete $self->get_method_map->{$method_name};
763 $self->remove_package_symbol(
764 { sigil => '&', type => 'CODE', name => $method_name }
767 $self->update_package_cache_flag; # still valid, since we just removed the method from the map
769 return $removed_method;
772 sub get_method_list {
774 keys %{$self->get_method_map};
777 sub find_method_by_name {
778 my ($self, $method_name) = @_;
779 (defined $method_name && $method_name)
780 || confess "You must define a method name to find";
781 foreach my $class ($self->linearized_isa) {
782 # fetch the meta-class ...
783 my $meta = $self->initialize($class);
784 return $meta->get_method($method_name)
785 if $meta->has_method($method_name);
790 sub compute_all_applicable_methods {
792 my (@methods, %seen_method);
793 foreach my $class ($self->linearized_isa) {
794 # fetch the meta-class ...
795 my $meta = $self->initialize($class);
796 foreach my $method_name ($meta->get_method_list()) {
797 next if exists $seen_method{$method_name};
798 $seen_method{$method_name}++;
800 name => $method_name,
802 code => $meta->get_method($method_name)
809 sub find_all_methods_by_name {
810 my ($self, $method_name) = @_;
811 (defined $method_name && $method_name)
812 || confess "You must define a method name to find";
814 foreach my $class ($self->linearized_isa) {
815 # fetch the meta-class ...
816 my $meta = $self->initialize($class);
818 name => $method_name,
820 code => $meta->get_method($method_name)
821 } if $meta->has_method($method_name);
826 sub find_next_method_by_name {
827 my ($self, $method_name) = @_;
828 (defined $method_name && $method_name)
829 || confess "You must define a method name to find";
830 my @cpl = $self->linearized_isa;
831 shift @cpl; # discard ourselves
832 foreach my $class (@cpl) {
833 # fetch the meta-class ...
834 my $meta = $self->initialize($class);
835 return $meta->get_method($method_name)
836 if $meta->has_method($method_name);
845 # either we have an attribute object already
846 # or we need to create one from the args provided
847 my $attribute = blessed($_[0]) ? $_[0] : $self->attribute_metaclass->new(@_);
848 # make sure it is derived from the correct type though
849 ($attribute->isa('Class::MOP::Attribute'))
850 || confess "Your attribute must be an instance of Class::MOP::Attribute (or a subclass)";
852 # first we attach our new attribute
853 # because it might need certain information
854 # about the class which it is attached to
855 $attribute->attach_to_class($self);
857 # then we remove attributes of a conflicting
858 # name here so that we can properly detach
859 # the old attr object, and remove any
860 # accessors it would have generated
861 if ( $self->has_attribute($attribute->name) ) {
862 $self->remove_attribute($attribute->name);
864 $self->invalidate_meta_instances();
867 # then onto installing the new accessors
868 $self->get_attribute_map->{$attribute->name} = $attribute;
870 # invalidate package flag here
871 my $e = do { local $@; eval { $attribute->install_accessors() }; $@ };
873 $self->remove_attribute($attribute->name);
880 sub update_meta_instance_dependencies {
883 if ( $self->{meta_instance_dependencies} ) {
884 return $self->add_meta_instance_dependencies;
888 sub add_meta_instance_dependencies {
891 $self->remove_meta_instance_depdendencies;
893 my @attrs = $self->compute_all_applicable_attributes();
896 my @classes = grep { not $seen{$_->name}++ } map { $_->associated_class } @attrs;
898 foreach my $class ( @classes ) {
899 $class->add_dependent_meta_instance($self);
902 $self->{meta_instance_dependencies} = \@classes;
905 sub remove_meta_instance_depdendencies {
908 if ( my $classes = delete $self->{meta_instance_dependencies} ) {
909 foreach my $class ( @$classes ) {
910 $class->remove_dependent_meta_instance($self);
920 sub add_dependent_meta_instance {
921 my ( $self, $metaclass ) = @_;
922 push @{ $self->{dependent_meta_instances} }, $metaclass;
925 sub remove_dependent_meta_instance {
926 my ( $self, $metaclass ) = @_;
927 my $name = $metaclass->name;
928 @$_ = grep { $_->name ne $name } @$_ for $self->{dependent_meta_instances};
931 sub invalidate_meta_instances {
933 $_->invalidate_meta_instance() for $self, @{ $self->{dependent_meta_instances} };
936 sub invalidate_meta_instance {
938 undef $self->{_meta_instance};
942 my ($self, $attribute_name) = @_;
943 (defined $attribute_name && $attribute_name)
944 || confess "You must define an attribute name";
945 exists $self->get_attribute_map->{$attribute_name} ? 1 : 0;
949 my ($self, $attribute_name) = @_;
950 (defined $attribute_name && $attribute_name)
951 || confess "You must define an attribute name";
952 return $self->get_attribute_map->{$attribute_name}
954 # this will return undef anyway, so no need ...
955 # if $self->has_attribute($attribute_name);
959 sub remove_attribute {
960 my ($self, $attribute_name) = @_;
961 (defined $attribute_name && $attribute_name)
962 || confess "You must define an attribute name";
963 my $removed_attribute = $self->get_attribute_map->{$attribute_name};
964 return unless defined $removed_attribute;
965 delete $self->get_attribute_map->{$attribute_name};
966 $self->invalidate_meta_instances();
967 $removed_attribute->remove_accessors();
968 $removed_attribute->detach_from_class();
969 return $removed_attribute;
972 sub get_attribute_list {
974 keys %{$self->get_attribute_map};
977 sub compute_all_applicable_attributes {
979 my (@attrs, %seen_attr);
980 foreach my $class ($self->linearized_isa) {
981 # fetch the meta-class ...
982 my $meta = $self->initialize($class);
983 foreach my $attr_name ($meta->get_attribute_list()) {
984 next if exists $seen_attr{$attr_name};
985 $seen_attr{$attr_name}++;
986 push @attrs => $meta->get_attribute($attr_name);
992 sub find_attribute_by_name {
993 my ($self, $attr_name) = @_;
994 foreach my $class ($self->linearized_isa) {
995 # fetch the meta-class ...
996 my $meta = $self->initialize($class);
997 return $meta->get_attribute($attr_name)
998 if $meta->has_attribute($attr_name);
1005 sub is_mutable { 1 }
1006 sub is_immutable { 0 }
1009 # Why I changed this (groditi)
1010 # - One Metaclass may have many Classes through many Metaclass instances
1011 # - One Metaclass should only have one Immutable Transformer instance
1012 # - Each Class may have different Immutabilizing options
1013 # - Therefore each Metaclass instance may have different Immutabilizing options
1014 # - We need to store one Immutable Transformer instance per Metaclass
1015 # - We need to store one set of Immutable Transformer options per Class
1016 # - Upon make_mutable we may delete the Immutabilizing options
1017 # - We could clean the immutable Transformer instance when there is no more
1018 # immutable Classes of that type, but we can also keep it in case
1019 # another class with this same Metaclass becomes immutable. It is a case
1020 # of trading of storing an instance to avoid unnecessary instantiations of
1021 # Immutable Transformers. You may view this as a memory leak, however
1022 # Because we have few Metaclasses, in practice it seems acceptable
1023 # - To allow Immutable Transformers instances to be cleaned up we could weaken
1024 # the reference stored in $IMMUTABLE_TRANSFORMERS{$class} and ||= should DWIM
1028 my %IMMUTABLE_TRANSFORMERS;
1029 my %IMMUTABLE_OPTIONS;
1031 sub get_immutable_options {
1033 return if $self->is_mutable;
1034 confess "unable to find immutabilizing options"
1035 unless exists $IMMUTABLE_OPTIONS{$self->name};
1036 my %options = %{$IMMUTABLE_OPTIONS{$self->name}};
1037 delete $options{IMMUTABLE_TRANSFORMER};
1041 sub get_immutable_transformer {
1043 if( $self->is_mutable ){
1044 my $class = blessed $self || $self;
1045 return $IMMUTABLE_TRANSFORMERS{$class} ||= $self->create_immutable_transformer;
1047 confess "unable to find transformer for immutable class"
1048 unless exists $IMMUTABLE_OPTIONS{$self->name};
1049 return $IMMUTABLE_OPTIONS{$self->name}->{IMMUTABLE_TRANSFORMER};
1052 sub make_immutable {
1056 my $transformer = $self->get_immutable_transformer;
1057 $transformer->make_metaclass_immutable($self, \%options);
1058 $IMMUTABLE_OPTIONS{$self->name} =
1059 { %options, IMMUTABLE_TRANSFORMER => $transformer };
1061 if( exists $options{debug} && $options{debug} ){
1062 print STDERR "# of Metaclass options: ", keys %IMMUTABLE_OPTIONS;
1063 print STDERR "# of Immutable transformers: ", keys %IMMUTABLE_TRANSFORMERS;
1071 return if $self->is_mutable;
1072 my $options = delete $IMMUTABLE_OPTIONS{$self->name};
1073 confess "unable to find immutabilizing options" unless ref $options;
1074 my $transformer = delete $options->{IMMUTABLE_TRANSFORMER};
1075 $transformer->make_metaclass_mutable($self, $options);
1080 sub create_immutable_transformer {
1082 my $class = Class::MOP::Immutable->new($self, {
1083 read_only => [qw/superclasses/],
1090 remove_package_symbol
1093 class_precedence_list => 'ARRAY',
1094 linearized_isa => 'ARRAY',
1095 compute_all_applicable_attributes => 'ARRAY',
1096 get_meta_instance => 'SCALAR',
1097 get_method_map => 'SCALAR',
1100 # this is ugly, but so are typeglobs,
1101 # so whattayahgonnadoboutit
1104 add_package_symbol => sub {
1105 my $original = shift;
1106 confess "Cannot add package symbols to an immutable metaclass"
1107 unless (caller(2))[3] eq 'Class::MOP::Package::get_package_symbol';
1108 goto $original->body;
1123 Class::MOP::Class - Class Meta Object
1127 # assuming that class Foo
1128 # has been defined, you can
1130 # use this for introspection ...
1132 # add a method to Foo ...
1133 Foo->meta->add_method('bar' => sub { ... })
1135 # get a list of all the classes searched
1136 # the method dispatcher in the correct order
1137 Foo->meta->class_precedence_list()
1139 # remove a method from Foo
1140 Foo->meta->remove_method('bar');
1142 # or use this to actually create classes ...
1144 Class::MOP::Class->create('Bar' => (
1146 superclasses => [ 'Foo' ],
1148 Class::MOP:::Attribute->new('$bar'),
1149 Class::MOP:::Attribute->new('$baz'),
1152 calculate_bar => sub { ... },
1153 construct_baz => sub { ... }
1159 This is the largest and currently most complex part of the Perl 5
1160 meta-object protocol. It controls the introspection and
1161 manipulation of Perl 5 classes (and it can create them too). The
1162 best way to understand what this module can do, is to read the
1163 documentation for each of it's methods.
1167 =head2 Self Introspection
1173 This will return a B<Class::MOP::Class> instance which is related
1174 to this class. Thereby allowing B<Class::MOP::Class> to actually
1177 As with B<Class::MOP::Attribute>, B<Class::MOP> will actually
1178 bootstrap this module by installing a number of attribute meta-objects
1179 into it's metaclass. This will allow this class to reap all the benifits
1180 of the MOP when subclassing it.
1184 =head2 Class construction
1186 These methods will handle creating B<Class::MOP::Class> objects,
1187 which can be used to both create new classes, and analyze
1188 pre-existing classes.
1190 This module will internally store references to all the instances
1191 you create with these methods, so that they do not need to be
1192 created any more than nessecary. Basically, they are singletons.
1196 =item B<create ($package_name,
1197 version =E<gt> ?$version,
1198 authority =E<gt> ?$authority,
1199 superclasses =E<gt> ?@superclasses,
1200 methods =E<gt> ?%methods,
1201 attributes =E<gt> ?%attributes)>
1203 This returns a B<Class::MOP::Class> object, bringing the specified
1204 C<$package_name> into existence and adding any of the C<$version>,
1205 C<$authority>, C<@superclasses>, C<%methods> and C<%attributes> to
1208 =item B<create_anon_class (superclasses =E<gt> ?@superclasses,
1209 methods =E<gt> ?%methods,
1210 attributes =E<gt> ?%attributes)>
1212 This will create an anonymous class, it works much like C<create> but
1213 it does not need a C<$package_name>. Instead it will create a suitably
1214 unique package name for you to stash things into.
1216 On very important distinction is that anon classes are destroyed once
1217 the metaclass they are attached to goes out of scope. In the DESTROY
1218 method, the created package will be removed from the symbol table.
1220 It is also worth noting that any instances created with an anon-class
1221 will keep a special reference to the anon-meta which will prevent the
1222 anon-class from going out of scope until all instances of it have also
1223 been destroyed. This however only works for HASH based instance types,
1224 as we use a special reserved slot (C<__MOP__>) to store this.
1226 =item B<initialize ($package_name, %options)>
1228 This initializes and returns returns a B<Class::MOP::Class> object
1229 for a given a C<$package_name>.
1231 =item B<reinitialize ($package_name, %options)>
1233 This removes the old metaclass, and creates a new one in it's place.
1234 Do B<not> use this unless you really know what you are doing, it could
1235 very easily make a very large mess of your program.
1237 =item B<construct_class_instance (%options)>
1239 This will construct an instance of B<Class::MOP::Class>, it is
1240 here so that we can actually "tie the knot" for B<Class::MOP::Class>
1241 to use C<construct_instance> once all the bootstrapping is done. This
1242 method is used internally by C<initialize> and should never be called
1243 from outside of that method really.
1245 =item B<check_metaclass_compatability>
1247 This method is called as the very last thing in the
1248 C<construct_class_instance> method. This will check that the
1249 metaclass you are creating is compatible with the metaclasses of all
1250 your ancestors. For more inforamtion about metaclass compatibility
1251 see the C<About Metaclass compatibility> section in L<Class::MOP>.
1253 =item B<update_package_cache_flag>
1255 This will reset the package cache flag for this particular metaclass
1256 it is basically the value of the C<Class::MOP::get_package_cache_flag>
1257 function. This is very rarely needed from outside of C<Class::MOP::Class>
1258 but in some cases you might want to use it, so it is here.
1260 =item B<reset_package_cache_flag>
1262 Clears the package cache flag to announce to the internals that we need
1263 to rebuild the method map.
1265 =item B<add_meta_instance_dependencies>
1267 Registers this class as dependent on its superclasses.
1269 Only superclasses from which this class inherits attributes will be added.
1271 =item B<remove_meta_instance_depdendencies>
1273 Unregisters this class from its superclasses.
1275 =item B<update_meta_instance_dependencies>
1277 Reregisters if necessary.
1279 =item B<add_dependent_meta_instance> $metaclass
1281 Registers the class as having a meta instance dependent on this class.
1283 =item B<remove_dependent_meta_instance> $metaclass
1285 Remove the class from the list of dependent classes.
1287 =item B<invalidate_meta_instances>
1289 Clears the cached meta instance for this metaclass and all of the registered
1290 classes with dependent meta instances.
1292 Called by C<add_attribute> and C<remove_attribute> to recalculate the attribute
1295 =item B<invalidate_meta_instance>
1297 Used by C<invalidate_meta_instances>.
1301 =head2 Object instance construction and cloning
1303 These methods are B<entirely optional>, it is up to you whether you want
1308 =item B<instance_metaclass>
1310 Returns the class name of the instance metaclass, see L<Class::MOP::Instance>
1311 for more information on the instance metaclasses.
1313 =item B<get_meta_instance>
1315 Returns an instance of L<Class::MOP::Instance> to be used in the construction
1316 of a new instance of the class.
1318 =item B<create_meta_instance>
1320 Called by C<get_meta_instance> if necessary.
1322 =item B<new_object (%params)>
1324 This is a convience method for creating a new object of the class, and
1325 blessing it into the appropriate package as well. Ideally your class
1326 would call a C<new> this method like so:
1329 my ($class, %param) = @_;
1330 $class->meta->new_object(%params);
1333 =item B<construct_instance (%params)>
1335 This method is used to construct an instance structure suitable for
1336 C<bless>-ing into your package of choice. It works in conjunction
1337 with the Attribute protocol to collect all applicable attributes.
1339 This will construct and instance using a HASH ref as storage
1340 (currently only HASH references are supported). This will collect all
1341 the applicable attributes and layout out the fields in the HASH ref,
1342 it will then initialize them using either use the corresponding key
1343 in C<%params> or any default value or initializer found in the
1344 attribute meta-object.
1346 =item B<clone_object ($instance, %params)>
1348 This is a convience method for cloning an object instance, then
1349 blessing it into the appropriate package. This method will call
1350 C<clone_instance>, which performs a shallow copy of the object,
1351 see that methods documentation for more details. Ideally your
1352 class would call a C<clone> this method like so:
1354 sub MyClass::clone {
1355 my ($self, %param) = @_;
1356 $self->meta->clone_object($self, %params);
1359 =item B<clone_instance($instance, %params)>
1361 This method is a compliment of C<construct_instance> (which means if
1362 you override C<construct_instance>, you need to override this one too),
1363 and clones the instance shallowly.
1365 The cloned structure returned is (like with C<construct_instance>) an
1366 unC<bless>ed HASH reference, it is your responsibility to then bless
1367 this cloned structure into the right class (which C<clone_object> will
1370 As of 0.11, this method will clone the C<$instance> structure shallowly,
1371 as opposed to the deep cloning implemented in prior versions. After much
1372 thought, research and discussion, I have decided that anything but basic
1373 shallow cloning is outside the scope of the meta-object protocol. I
1374 think Yuval "nothingmuch" Kogman put it best when he said that cloning
1375 is too I<context-specific> to be part of the MOP.
1377 =item B<rebless_instance($instance, ?%params)>
1379 This will change the class of C<$instance> to the class of the invoking
1380 C<Class::MOP::Class>. You may only rebless the instance to a subclass of
1381 itself. You may pass in optional C<%params> which are like constructor
1382 params and will override anything already defined in the instance.
1386 =head2 Informational
1388 These are a few predicate methods for asking information about the class.
1392 =item B<is_anon_class>
1394 This returns true if the class is a C<Class::MOP::Class> created anon class.
1398 This returns true if the class is still mutable.
1400 =item B<is_immutable>
1402 This returns true if the class has been made immutable.
1406 =head2 Inheritance Relationships
1410 =item B<superclasses (?@superclasses)>
1412 This is a read-write attribute which represents the superclass
1413 relationships of the class the B<Class::MOP::Class> instance is
1414 associated with. Basically, it can get and set the C<@ISA> for you.
1416 =item B<class_precedence_list>
1418 This computes the a list of all the class's ancestors in the same order
1419 in which method dispatch will be done. This is similair to what
1420 B<Class::ISA::super_path> does, but we don't remove duplicate names.
1422 =item B<linearized_isa>
1424 This returns a list based on C<class_precedence_list> but with all
1429 This returns a list of subclasses for this class.
1437 =item B<get_method_map>
1439 Returns a HASH ref of name to CODE reference mapping for this class.
1441 =item B<method_metaclass>
1443 Returns the class name of the method metaclass, see L<Class::MOP::Method>
1444 for more information on the method metaclasses.
1446 =item B<add_method ($method_name, $method)>
1448 This will take a C<$method_name> and CODE reference to that
1449 C<$method> and install it into the class's package.
1452 This does absolutely nothing special to C<$method>
1453 other than use B<Sub::Name> to make sure it is tagged with the
1454 correct name, and therefore show up correctly in stack traces and
1457 =item B<alias_method ($method_name, $method)>
1459 This will take a C<$method_name> and CODE reference to that
1460 C<$method> and alias the method into the class's package.
1463 Unlike C<add_method>, this will B<not> try to name the
1464 C<$method> using B<Sub::Name>, it only aliases the method in
1465 the class's package.
1467 =item B<has_method ($method_name)>
1469 This just provides a simple way to check if the class implements
1470 a specific C<$method_name>. It will I<not> however, attempt to check
1471 if the class inherits the method (use C<UNIVERSAL::can> for that).
1473 This will correctly handle functions defined outside of the package
1474 that use a fully qualified name (C<sub Package::name { ... }>).
1476 This will correctly handle functions renamed with B<Sub::Name> and
1477 installed using the symbol tables. However, if you are naming the
1478 subroutine outside of the package scope, you must use the fully
1479 qualified name, including the package name, for C<has_method> to
1480 correctly identify it.
1482 This will attempt to correctly ignore functions imported from other
1483 packages using B<Exporter>. It breaks down if the function imported
1484 is an C<__ANON__> sub (such as with C<use constant>), which very well
1485 may be a valid method being applied to the class.
1487 In short, this method cannot always be trusted to determine if the
1488 C<$method_name> is actually a method. However, it will DWIM about
1489 90% of the time, so it's a small trade off I think.
1491 =item B<get_method ($method_name)>
1493 This will return a Class::MOP::Method instance related to the specified
1494 C<$method_name>, or return undef if that method does not exist.
1496 The Class::MOP::Method is codifiable, so you can use it like a normal
1497 CODE reference, see L<Class::MOP::Method> for more information.
1499 =item B<find_method_by_name ($method_name)>
1501 This will return a CODE reference of the specified C<$method_name>,
1502 or return undef if that method does not exist.
1504 Unlike C<get_method> this will also look in the superclasses.
1506 =item B<remove_method ($method_name)>
1508 This will attempt to remove a given C<$method_name> from the class.
1509 It will return the CODE reference that it has removed, and will
1510 attempt to use B<Sub::Name> to clear the methods associated name.
1512 =item B<get_method_list>
1514 This will return a list of method names for all I<locally> defined
1515 methods. It does B<not> provide a list of all applicable methods,
1516 including any inherited ones. If you want a list of all applicable
1517 methods, use the C<compute_all_applicable_methods> method.
1519 =item B<compute_all_applicable_methods>
1521 This will return a list of all the methods names this class will
1522 respond to, taking into account inheritance. The list will be a list of
1523 HASH references, each one containing the following information; method
1524 name, the name of the class in which the method lives and a CODE
1525 reference for the actual method.
1527 =item B<find_all_methods_by_name ($method_name)>
1529 This will traverse the inheritence hierarchy and locate all methods
1530 with a given C<$method_name>. Similar to
1531 C<compute_all_applicable_methods> it returns a list of HASH references
1532 with the following information; method name (which will always be the
1533 same as C<$method_name>), the name of the class in which the method
1534 lives and a CODE reference for the actual method.
1536 The list of methods produced is a distinct list, meaning there are no
1537 duplicates in it. This is especially useful for things like object
1538 initialization and destruction where you only want the method called
1539 once, and in the correct order.
1541 =item B<find_next_method_by_name ($method_name)>
1543 This will return the first method to match a given C<$method_name> in
1544 the superclasses, this is basically equivalent to calling
1545 C<SUPER::$method_name>, but it can be dispatched at runtime.
1549 =head2 Method Modifiers
1551 Method modifiers are a concept borrowed from CLOS, in which a method
1552 can be wrapped with I<before>, I<after> and I<around> method modifiers
1553 that will be called everytime the method is called.
1555 =head3 How method modifiers work?
1557 Method modifiers work by wrapping the original method and then replacing
1558 it in the classes symbol table. The wrappers will handle calling all the
1559 modifiers in the appropariate orders and preserving the calling context
1560 for the original method.
1562 Each method modifier serves a particular purpose, which may not be
1563 obvious to users of other method wrapping modules. To start with, the
1564 return values of I<before> and I<after> modifiers are ignored. This is
1565 because thier purpose is B<not> to filter the input and output of the
1566 primary method (this is done with an I<around> modifier). This may seem
1567 like an odd restriction to some, but doing this allows for simple code
1568 to be added at the begining or end of a method call without jeapordizing
1569 the normal functioning of the primary method or placing any extra
1570 responsibility on the code of the modifier. Of course if you have more
1571 complex needs, then use the I<around> modifier, which uses a variation
1572 of continutation passing style to allow for a high degree of flexibility.
1574 Before and around modifiers are called in last-defined-first-called order,
1575 while after modifiers are called in first-defined-first-called order. So
1576 the call tree might looks something like this:
1586 To see examples of using method modifiers, see the following examples
1587 included in the distribution; F<InstanceCountingClass>, F<Perl6Attribute>,
1588 F<AttributesWithHistory> and F<C3MethodDispatchOrder>. There is also a
1589 classic CLOS usage example in the test F<017_add_method_modifier.t>.
1591 =head3 What is the performance impact?
1593 Of course there is a performance cost associated with method modifiers,
1594 but we have made every effort to make that cost be directly proportional
1595 to the amount of modifier features you utilize.
1597 The wrapping method does it's best to B<only> do as much work as it
1598 absolutely needs to. In order to do this we have moved some of the
1599 performance costs to set-up time, where they are easier to amortize.
1601 All this said, my benchmarks have indicated the following:
1603 simple wrapper with no modifiers 100% slower
1604 simple wrapper with simple before modifier 400% slower
1605 simple wrapper with simple after modifier 450% slower
1606 simple wrapper with simple around modifier 500-550% slower
1607 simple wrapper with all 3 modifiers 1100% slower
1609 These numbers may seem daunting, but you must remember, every feature
1610 comes with some cost. To put things in perspective, just doing a simple
1611 C<AUTOLOAD> which does nothing but extract the name of the method called
1612 and return it costs about 400% over a normal method call.
1616 =item B<add_before_method_modifier ($method_name, $code)>
1618 This will wrap the method at C<$method_name> and the supplied C<$code>
1619 will be passed the C<@_> arguments, and called before the original
1620 method is called. As specified above, the return value of the I<before>
1621 method modifiers is ignored, and it's ability to modify C<@_> is
1622 fairly limited. If you need to do either of these things, use an
1623 C<around> method modifier.
1625 =item B<add_after_method_modifier ($method_name, $code)>
1627 This will wrap the method at C<$method_name> so that the original
1628 method will be called, it's return values stashed, and then the
1629 supplied C<$code> will be passed the C<@_> arguments, and called.
1630 As specified above, the return value of the I<after> method
1631 modifiers is ignored, and it cannot modify the return values of
1632 the original method. If you need to do either of these things, use an
1633 C<around> method modifier.
1635 =item B<add_around_method_modifier ($method_name, $code)>
1637 This will wrap the method at C<$method_name> so that C<$code>
1638 will be called and passed the original method as an extra argument
1639 at the begining of the C<@_> argument list. This is a variation of
1640 continuation passing style, where the function prepended to C<@_>
1641 can be considered a continuation. It is up to C<$code> if it calls
1642 the original method or not, there is no restriction on what the
1643 C<$code> can or cannot do.
1649 It should be noted that since there is no one consistent way to define
1650 the attributes of a class in Perl 5. These methods can only work with
1651 the information given, and can not easily discover information on
1652 their own. See L<Class::MOP::Attribute> for more details.
1656 =item B<attribute_metaclass>
1658 Returns the class name of the attribute metaclass, see L<Class::MOP::Attribute>
1659 for more information on the attribute metaclasses.
1661 =item B<get_attribute_map>
1663 This returns a HASH ref of name to attribute meta-object mapping.
1665 =item B<add_attribute ($attribute_meta_object | ($attribute_name, %attribute_spec))>
1667 This stores the C<$attribute_meta_object> (or creates one from the
1668 C<$attribute_name> and C<%attribute_spec>) in the B<Class::MOP::Class>
1669 instance associated with the given class. Unlike methods, attributes
1670 within the MOP are stored as meta-information only. They will be used
1671 later to construct instances from (see C<construct_instance> above).
1672 More details about the attribute meta-objects can be found in the
1673 L<Class::MOP::Attribute> or the L<Class::MOP/The Attribute protocol>
1676 It should be noted that any accessor, reader/writer or predicate
1677 methods which the C<$attribute_meta_object> has will be installed
1678 into the class at this time.
1681 If an attribute already exists for C<$attribute_name>, the old one
1682 will be removed (as well as removing all it's accessors), and then
1685 =item B<has_attribute ($attribute_name)>
1687 Checks to see if this class has an attribute by the name of
1688 C<$attribute_name> and returns a boolean.
1690 =item B<get_attribute ($attribute_name)>
1692 Returns the attribute meta-object associated with C<$attribute_name>,
1693 if none is found, it will return undef.
1695 =item B<remove_attribute ($attribute_name)>
1697 This will remove the attribute meta-object stored at
1698 C<$attribute_name>, then return the removed attribute meta-object.
1701 Removing an attribute will only affect future instances of
1702 the class, it will not make any attempt to remove the attribute from
1703 any existing instances of the class.
1705 It should be noted that any accessor, reader/writer or predicate
1706 methods which the attribute meta-object stored at C<$attribute_name>
1707 has will be removed from the class at this time. This B<will> make
1708 these attributes somewhat inaccessable in previously created
1709 instances. But if you are crazy enough to do this at runtime, then
1710 you are crazy enough to deal with something like this :).
1712 =item B<get_attribute_list>
1714 This returns a list of attribute names which are defined in the local
1715 class. If you want a list of all applicable attributes for a class,
1716 use the C<compute_all_applicable_attributes> method.
1718 =item B<compute_all_applicable_attributes>
1720 This will traverse the inheritance heirachy and return a list of all
1721 the applicable attributes for this class. It does not construct a
1722 HASH reference like C<compute_all_applicable_methods> because all
1723 that same information is discoverable through the attribute
1726 =item B<find_attribute_by_name ($attr_name)>
1728 This method will traverse the inheritance heirachy and find the
1729 first attribute whose name matches C<$attr_name>, then return it.
1730 It will return undef if nothing is found.
1734 =head2 Class Immutability
1738 =item B<make_immutable (%options)>
1740 This method will invoke a tranforamtion upon the class which will
1741 make it immutable. Details of this transformation can be found in
1742 the L<Class::MOP::Immutable> documentation.
1744 =item B<make_mutable>
1746 This method will reverse tranforamtion upon the class which
1749 =item B<get_immutable_transformer>
1751 Return a transformer suitable for making this class immutable or, if this
1752 class is immutable, the transformer used to make it immutable.
1754 =item B<get_immutable_options>
1756 If the class is immutable, return the options used to make it immutable.
1758 =item B<create_immutable_transformer>
1760 Create a transformer suitable for making this class immutable
1766 Stevan Little E<lt>stevan@iinteractive.comE<gt>
1768 =head1 COPYRIGHT AND LICENSE
1770 Copyright 2006-2008 by Infinity Interactive, Inc.
1772 L<http://www.iinteractive.com>
1774 This library is free software; you can redistribute it and/or modify
1775 it under the same terms as Perl itself.