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 {
57 my $options = @_ == 1 ? $_[0] : {@_};
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
76 ? ($class->is_immutable
77 ? $class->get_mutable_metaclass_name()
81 # now create the metaclass
83 if ($class eq 'Class::MOP::Class') {
85 $meta = $class->_new($options)
89 # it is safe to use meta here because
90 # class will always be a subclass of
91 # Class::MOP::Class, which defines meta
92 $meta = $class->meta->construct_instance($options)
95 # and check the metaclass compatibility
96 $meta->check_metaclass_compatability();
98 Class::MOP::store_metaclass_by_name($package_name, $meta);
101 # we need to weaken any anon classes
102 # so that they can call DESTROY properly
103 Class::MOP::weaken_metaclass($package_name) if $meta->is_anon_class;
110 my $options = @_ == 1 ? $_[0] : {@_};
113 # inherited from Class::MOP::Package
114 'package' => $options->{package},
117 # since the following attributes will
118 # actually be loaded from the symbol
119 # table, and actually bypass the instance
120 # entirely, we can just leave these things
121 # listed here for reference, because they
122 # should not actually have a value associated
124 'namespace' => \undef,
125 # inherited from Class::MOP::Module
127 'authority' => \undef,
128 # defined in Class::MOP::Class
129 'superclasses' => \undef,
133 'attribute_metaclass' => $options->{'attribute_metaclass'} || 'Class::MOP::Attribute',
134 'method_metaclass' => $options->{'method_metaclass'} || 'Class::MOP::Method',
135 'instance_metaclass' => $options->{'instance_metaclass'} || 'Class::MOP::Instance',
139 sub reset_package_cache_flag { (shift)->{'_package_cache_flag'} = undef }
140 sub update_package_cache_flag {
143 # we can manually update the cache number
144 # since we are actually adding the method
145 # to our cache as well. This avoids us
146 # having to regenerate the method_map.
148 $self->{'_package_cache_flag'} = Class::MOP::check_package_cache_flag($self->name);
151 sub check_metaclass_compatability {
154 # this is always okay ...
155 return if ref($self) eq 'Class::MOP::Class' &&
156 $self->instance_metaclass eq 'Class::MOP::Instance';
158 my @class_list = $self->linearized_isa;
159 shift @class_list; # shift off $self->name
161 foreach my $class_name (@class_list) {
162 my $meta = Class::MOP::get_metaclass_by_name($class_name) || next;
165 # we need to deal with the possibility
166 # of class immutability here, and then
167 # get the name of the class appropriately
168 my $meta_type = ($meta->is_immutable
169 ? $meta->get_mutable_metaclass_name()
172 ($self->isa($meta_type))
173 || confess $self->name . "->meta => (" . (ref($self)) . ")" .
174 " is not compatible with the " .
175 $class_name . "->meta => (" . ($meta_type) . ")";
177 # we also need to check that instance metaclasses
178 # are compatabile in the same the class.
179 ($self->instance_metaclass->isa($meta->instance_metaclass))
180 || confess $self->name . "->meta => (" . ($self->instance_metaclass) . ")" .
181 " is not compatible with the " .
182 $class_name . "->meta => (" . ($meta->instance_metaclass) . ")";
190 # this should be sufficient, if you have a
191 # use case where it is not, write a test and
193 my $ANON_CLASS_SERIAL = 0;
196 # we need a sufficiently annoying prefix
197 # this should suffice for now, this is
198 # used in a couple of places below, so
199 # need to put it up here for now.
200 my $ANON_CLASS_PREFIX = 'Class::MOP::Class::__ANON__::SERIAL::';
204 no warnings 'uninitialized';
205 $self->name =~ /^$ANON_CLASS_PREFIX/;
208 sub create_anon_class {
209 my ($class, %options) = @_;
210 my $package_name = $ANON_CLASS_PREFIX . ++$ANON_CLASS_SERIAL;
211 return $class->create($package_name, %options);
215 # this will only get called for
216 # anon-classes, all other calls
217 # are assumed to occur during
218 # global destruction and so don't
219 # really need to be handled explicitly
223 return if Class::MOP::in_global_destruction; # it'll happen soon anyway and this just makes things more complicated
225 no warnings 'uninitialized';
226 return unless $self->name =~ /^$ANON_CLASS_PREFIX/;
227 my ($serial_id) = ($self->name =~ /^$ANON_CLASS_PREFIX(\d+)/);
229 foreach my $key (keys %{$ANON_CLASS_PREFIX . $serial_id}) {
230 delete ${$ANON_CLASS_PREFIX . $serial_id}{$key};
232 delete ${'main::' . $ANON_CLASS_PREFIX}{$serial_id . '::'};
237 # creating classes with MOP ...
240 my ( $class, @args ) = @_;
242 unshift @args, 'package' if @args % 2 == 1;
244 my (%options) = @args;
245 my $package_name = $options{package};
247 (defined $package_name && $package_name)
248 || confess "You must pass a package name";
250 (ref $options{superclasses} eq 'ARRAY')
251 || confess "You must pass an ARRAY ref of superclasses"
252 if exists $options{superclasses};
254 (ref $options{attributes} eq 'ARRAY')
255 || confess "You must pass an ARRAY ref of attributes"
256 if exists $options{attributes};
258 (ref $options{methods} eq 'HASH')
259 || confess "You must pass an HASH ref of methods"
260 if exists $options{methods};
262 my $code = "package $package_name;";
263 $code .= "\$$package_name\:\:VERSION = '" . $options{version} . "';"
264 if exists $options{version};
265 $code .= "\$$package_name\:\:AUTHORITY = '" . $options{authority} . "';"
266 if exists $options{authority};
269 confess "creation of $package_name failed : $@" if $@;
271 my $meta = $class->initialize($package_name);
274 $meta->add_method('meta' => sub {
275 $class->initialize(ref($_[0]) || $_[0]);
278 $meta->superclasses(@{$options{superclasses}})
279 if exists $options{superclasses};
281 # process attributes first, so that they can
282 # install accessors, but locally defined methods
283 # can then overwrite them. It is maybe a little odd, but
284 # I think this should be the order of things.
285 if (exists $options{attributes}) {
286 foreach my $attr (@{$options{attributes}}) {
287 $meta->add_attribute($attr);
290 if (exists $options{methods}) {
291 foreach my $method_name (keys %{$options{methods}}) {
292 $meta->add_method($method_name, $options{methods}->{$method_name});
301 # all these attribute readers will be bootstrapped
302 # away in the Class::MOP bootstrap section
304 sub get_attribute_map { $_[0]->{'attributes'} }
305 sub attribute_metaclass { $_[0]->{'attribute_metaclass'} }
306 sub method_metaclass { $_[0]->{'method_metaclass'} }
307 sub instance_metaclass { $_[0]->{'instance_metaclass'} }
310 # this is a prime canidate for conversion to XS
314 my $current = Class::MOP::check_package_cache_flag($self->name);
316 if (defined $self->{'_package_cache_flag'} && $self->{'_package_cache_flag'} == $current) {
317 return $self->{'methods'} ||= {};
320 $self->{_package_cache_flag} = $current;
322 my $map = $self->{'methods'} ||= {};
324 my $class_name = $self->name;
325 my $method_metaclass = $self->method_metaclass;
327 my %all_code = $self->get_all_package_symbols('CODE');
329 foreach my $symbol (keys %all_code) {
330 my $code = $all_code{$symbol};
332 next if exists $map->{$symbol} &&
333 defined $map->{$symbol} &&
334 $map->{$symbol}->body == $code;
336 my ($pkg, $name) = Class::MOP::get_code_info($code);
339 # in 5.10 constant.pm the constants show up
340 # as being in the right package, but in pre-5.10
341 # they show up as constant::__ANON__ so we
342 # make an exception here to be sure that things
343 # work as expected in both.
345 unless ($pkg eq 'constant' && $name eq '__ANON__') {
346 next if ($pkg || '') ne $class_name ||
347 (($name || '') ne '__ANON__' && ($pkg || '') ne $class_name);
350 $map->{$symbol} = $method_metaclass->wrap(
352 associated_metaclass => $self,
353 package_name => $class_name,
361 # Instance Construction & Cloning
367 # we need to protect the integrity of the
368 # Class::MOP::Class singletons here, so we
369 # delegate this to &construct_class_instance
370 # which will deal with the singletons
371 return $class->construct_class_instance(@_)
372 if $class->name->isa('Class::MOP::Class');
373 return $class->construct_instance(@_);
376 sub construct_instance {
378 my $params = @_ == 1 ? $_[0] : {@_};
379 my $meta_instance = $class->get_meta_instance();
380 my $instance = $meta_instance->create_instance();
381 foreach my $attr ($class->compute_all_applicable_attributes()) {
382 $attr->initialize_instance_slot($meta_instance, $instance, $params);
385 # this will only work for a HASH instance type
386 if ($class->is_anon_class) {
387 (Scalar::Util::reftype($instance) eq 'HASH')
388 || confess "Currently only HASH based instances are supported with instance of anon-classes";
390 # At some point we should make this official
391 # as a reserved slot name, but right now I am
392 # going to keep it here.
393 # my $RESERVED_MOP_SLOT = '__MOP__';
394 $instance->{'__MOP__'} = $class;
400 sub get_meta_instance {
402 $self->{'_meta_instance'} ||= $self->create_meta_instance();
405 sub create_meta_instance {
408 my $instance = $self->instance_metaclass->new(
409 associated_metaclass => $self,
410 attributes => [ $self->compute_all_applicable_attributes() ],
413 $self->add_meta_instance_dependencies()
414 if $instance->is_dependent_on_superclasses();
421 my $instance = shift;
422 (blessed($instance) && $instance->isa($class->name))
423 || confess "You must pass an instance of the metaclass (" . (ref $class ? $class->name : $class) . "), not ($instance)";
426 # we need to protect the integrity of the
427 # Class::MOP::Class singletons here, they
428 # should not be cloned.
429 return $instance if $instance->isa('Class::MOP::Class');
430 $class->clone_instance($instance, @_);
434 my ($class, $instance, %params) = @_;
436 || confess "You can only clone instances, ($instance) is not a blessed instance";
437 my $meta_instance = $class->get_meta_instance();
438 my $clone = $meta_instance->clone_instance($instance);
439 foreach my $attr ($class->compute_all_applicable_attributes()) {
440 if ( defined( my $init_arg = $attr->init_arg ) ) {
441 if (exists $params{$init_arg}) {
442 $attr->set_value($clone, $params{$init_arg});
449 sub rebless_instance {
450 my ($self, $instance, %params) = @_;
453 if ($instance->can('meta')) {
454 ($instance->meta->isa('Class::MOP::Class'))
455 || confess 'Cannot rebless instance if ->meta is not an instance of Class::MOP::Class';
456 $old_metaclass = $instance->meta;
459 $old_metaclass = $self->initialize(ref($instance));
462 my $meta_instance = $self->get_meta_instance();
464 $self->name->isa($old_metaclass->name)
465 || confess "You may rebless only into a subclass of (". $old_metaclass->name ."), of which (". $self->name .") isn't.";
468 $meta_instance->rebless_instance_structure($instance, $self);
470 foreach my $attr ( $self->compute_all_applicable_attributes ) {
471 if ( $attr->has_value($instance) ) {
472 if ( defined( my $init_arg = $attr->init_arg ) ) {
473 $params{$init_arg} = $attr->get_value($instance)
474 unless exists $params{$init_arg};
477 $attr->set_value($instance, $attr->get_value($instance));
482 foreach my $attr ($self->compute_all_applicable_attributes) {
483 $attr->initialize_instance_slot($meta_instance, $instance, \%params);
493 my $var_spec = { sigil => '@', type => 'ARRAY', name => 'ISA' };
496 @{$self->get_package_symbol($var_spec)} = @supers;
498 # we need to check the metaclass
499 # compatibility here so that we can
500 # be sure that the superclass is
501 # not potentially creating an issues
502 # we don't know about
503 $self->check_metaclass_compatability();
504 $self->update_meta_instance_dependencies();
506 @{$self->get_package_symbol($var_spec)};
512 my $super_class = $self->name;
514 if ( Class::MOP::HAVE_ISAREV() ) {
515 return @{ $super_class->mro::get_isarev() };
519 my $find_derived_classes;
520 $find_derived_classes = sub {
521 my ($outer_class) = @_;
523 my $symbol_table_hashref = do { no strict 'refs'; \%{"${outer_class}::"} };
526 for my $symbol ( keys %$symbol_table_hashref ) {
527 next SYMBOL if $symbol !~ /\A (\w+):: \z/x;
528 my $inner_class = $1;
530 next SYMBOL if $inner_class eq 'SUPER'; # skip '*::SUPER'
534 ? "${outer_class}::$inner_class"
537 if ( $class->isa($super_class) and $class ne $super_class ) {
538 push @derived_classes, $class;
541 next SYMBOL if $class eq 'main'; # skip 'main::*'
543 $find_derived_classes->($class);
547 my $root_class = q{};
548 $find_derived_classes->($root_class);
550 undef $find_derived_classes;
552 @derived_classes = sort { $a->isa($b) ? 1 : $b->isa($a) ? -1 : 0 } @derived_classes;
554 return @derived_classes;
560 return @{ mro::get_linear_isa( (shift)->name ) };
563 sub class_precedence_list {
565 my $name = $self->name;
567 unless (Class::MOP::IS_RUNNING_ON_5_10()) {
569 # We need to check for circular inheritance here
570 # if we are are not on 5.10, cause 5.8 detects it
571 # late. This will do nothing if all is well, and
572 # blow up otherwise. Yes, it's an ugly hack, better
573 # suggestions are welcome.
575 ($name || return)->isa('This is a test for circular inheritance')
578 # if our mro is c3, we can
579 # just grab the linear_isa
580 if (mro::get_mro($name) eq 'c3') {
581 return @{ mro::get_linear_isa($name) }
585 # we can't grab the linear_isa for dfs
586 # since it has all the duplicates
591 $self->initialize($_)->class_precedence_list()
592 } $self->superclasses()
600 my ($self, $method_name, $method) = @_;
601 (defined $method_name && $method_name)
602 || confess "You must define a method name";
605 if (blessed($method)) {
606 $body = $method->body;
607 if ($method->package_name ne $self->name &&
608 $method->name ne $method_name) {
609 warn "Hello there, got something for you."
610 . " Method says " . $method->package_name . " " . $method->name
611 . " Class says " . $self->name . " " . $method_name;
612 $method = $method->clone(
613 package_name => $self->name,
615 ) if $method->can('clone');
620 ('CODE' eq ref($body))
621 || confess "Your code block must be a CODE reference";
622 $method = $self->method_metaclass->wrap(
624 package_name => $self->name,
630 $method->attach_to_class($self);
632 $self->get_method_map->{$method_name} = $method;
634 my $full_method_name = ($self->name . '::' . $method_name);
635 $self->add_package_symbol(
636 { sigil => '&', type => 'CODE', name => $method_name },
637 Class::MOP::subname($full_method_name => $body)
640 $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
644 my $fetch_and_prepare_method = sub {
645 my ($self, $method_name) = @_;
647 my $method = $self->get_method($method_name);
648 # if we dont have local ...
650 # try to find the next method
651 $method = $self->find_next_method_by_name($method_name);
652 # die if it does not exist
654 || confess "The method '$method_name' is not found in the inheritance hierarchy for class " . $self->name;
655 # and now make sure to wrap it
656 # even if it is already wrapped
657 # because we need a new sub ref
658 $method = Class::MOP::Method::Wrapped->wrap($method);
661 # now make sure we wrap it properly
662 $method = Class::MOP::Method::Wrapped->wrap($method)
663 unless $method->isa('Class::MOP::Method::Wrapped');
665 $self->add_method($method_name => $method);
669 sub add_before_method_modifier {
670 my ($self, $method_name, $method_modifier) = @_;
671 (defined $method_name && $method_name)
672 || confess "You must pass in a method name";
673 my $method = $fetch_and_prepare_method->($self, $method_name);
674 $method->add_before_modifier(
675 Class::MOP::subname(':before' => $method_modifier)
679 sub add_after_method_modifier {
680 my ($self, $method_name, $method_modifier) = @_;
681 (defined $method_name && $method_name)
682 || confess "You must pass in a method name";
683 my $method = $fetch_and_prepare_method->($self, $method_name);
684 $method->add_after_modifier(
685 Class::MOP::subname(':after' => $method_modifier)
689 sub add_around_method_modifier {
690 my ($self, $method_name, $method_modifier) = @_;
691 (defined $method_name && $method_name)
692 || confess "You must pass in a method name";
693 my $method = $fetch_and_prepare_method->($self, $method_name);
694 $method->add_around_modifier(
695 Class::MOP::subname(':around' => $method_modifier)
700 # the methods above used to be named like this:
701 # ${pkg}::${method}:(before|after|around)
702 # but this proved problematic when using one modifier
703 # to wrap multiple methods (something which is likely
704 # to happen pretty regularly IMO). So instead of naming
705 # it like this, I have chosen to just name them purely
706 # with their modifier names, like so:
707 # :(before|after|around)
708 # The fact is that in a stack trace, it will be fairly
709 # evident from the context what method they are attached
710 # to, and so don't need the fully qualified name.
714 my ($self, $method_name, $method) = @_;
715 (defined $method_name && $method_name)
716 || confess "You must define a method name";
718 my $body = (blessed($method) ? $method->body : $method);
719 ('CODE' eq ref($body))
720 || confess "Your code block must be a CODE reference";
722 $self->add_package_symbol(
723 { sigil => '&', type => 'CODE', name => $method_name } => $body
728 my ($self, $method_name) = @_;
729 (defined $method_name && $method_name)
730 || confess "You must define a method name";
732 return 0 unless exists $self->get_method_map->{$method_name};
737 my ($self, $method_name) = @_;
738 (defined $method_name && $method_name)
739 || confess "You must define a method name";
742 # I don't really need this here, because
743 # if the method_map is missing a key it
744 # will just return undef for me now
745 # return unless $self->has_method($method_name);
747 return $self->get_method_map->{$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);
995 sub is_immutable { 0 }
998 # Why I changed this (groditi)
999 # - One Metaclass may have many Classes through many Metaclass instances
1000 # - One Metaclass should only have one Immutable Transformer instance
1001 # - Each Class may have different Immutabilizing options
1002 # - Therefore each Metaclass instance may have different Immutabilizing options
1003 # - We need to store one Immutable Transformer instance per Metaclass
1004 # - We need to store one set of Immutable Transformer options per Class
1005 # - Upon make_mutable we may delete the Immutabilizing options
1006 # - We could clean the immutable Transformer instance when there is no more
1007 # immutable Classes of that type, but we can also keep it in case
1008 # another class with this same Metaclass becomes immutable. It is a case
1009 # of trading of storing an instance to avoid unnecessary instantiations of
1010 # Immutable Transformers. You may view this as a memory leak, however
1011 # Because we have few Metaclasses, in practice it seems acceptable
1012 # - To allow Immutable Transformers instances to be cleaned up we could weaken
1013 # the reference stored in $IMMUTABLE_TRANSFORMERS{$class} and ||= should DWIM
1017 my %IMMUTABLE_TRANSFORMERS;
1018 my %IMMUTABLE_OPTIONS;
1020 sub get_immutable_options {
1022 return if $self->is_mutable;
1023 confess "unable to find immutabilizing options"
1024 unless exists $IMMUTABLE_OPTIONS{$self->name};
1025 my %options = %{$IMMUTABLE_OPTIONS{$self->name}};
1026 delete $options{IMMUTABLE_TRANSFORMER};
1030 sub get_immutable_transformer {
1032 if( $self->is_mutable ){
1033 my $class = ref $self || $self;
1034 return $IMMUTABLE_TRANSFORMERS{$class} ||= $self->create_immutable_transformer;
1036 confess "unable to find transformer for immutable class"
1037 unless exists $IMMUTABLE_OPTIONS{$self->name};
1038 return $IMMUTABLE_OPTIONS{$self->name}->{IMMUTABLE_TRANSFORMER};
1041 sub make_immutable {
1045 my $transformer = $self->get_immutable_transformer;
1046 $transformer->make_metaclass_immutable($self, \%options);
1047 $IMMUTABLE_OPTIONS{$self->name} =
1048 { %options, IMMUTABLE_TRANSFORMER => $transformer };
1050 if( exists $options{debug} && $options{debug} ){
1051 print STDERR "# of Metaclass options: ", keys %IMMUTABLE_OPTIONS;
1052 print STDERR "# of Immutable transformers: ", keys %IMMUTABLE_TRANSFORMERS;
1060 return if $self->is_mutable;
1061 my $options = delete $IMMUTABLE_OPTIONS{$self->name};
1062 confess "unable to find immutabilizing options" unless ref $options;
1063 my $transformer = delete $options->{IMMUTABLE_TRANSFORMER};
1064 $transformer->make_metaclass_mutable($self, $options);
1069 sub create_immutable_transformer {
1071 my $class = Class::MOP::Immutable->new($self, {
1072 read_only => [qw/superclasses/],
1079 remove_package_symbol
1082 class_precedence_list => 'ARRAY',
1083 linearized_isa => 'ARRAY',
1084 compute_all_applicable_attributes => 'ARRAY',
1085 get_meta_instance => 'SCALAR',
1086 get_method_map => 'SCALAR',
1089 # this is ugly, but so are typeglobs,
1090 # so whattayahgonnadoboutit
1093 add_package_symbol => sub {
1094 my $original = shift;
1095 confess "Cannot add package symbols to an immutable metaclass"
1096 unless (caller(2))[3] eq 'Class::MOP::Package::get_package_symbol';
1097 goto $original->body;
1112 Class::MOP::Class - Class Meta Object
1116 # assuming that class Foo
1117 # has been defined, you can
1119 # use this for introspection ...
1121 # add a method to Foo ...
1122 Foo->meta->add_method('bar' => sub { ... })
1124 # get a list of all the classes searched
1125 # the method dispatcher in the correct order
1126 Foo->meta->class_precedence_list()
1128 # remove a method from Foo
1129 Foo->meta->remove_method('bar');
1131 # or use this to actually create classes ...
1133 Class::MOP::Class->create('Bar' => (
1135 superclasses => [ 'Foo' ],
1137 Class::MOP:::Attribute->new('$bar'),
1138 Class::MOP:::Attribute->new('$baz'),
1141 calculate_bar => sub { ... },
1142 construct_baz => sub { ... }
1148 This is the largest and currently most complex part of the Perl 5
1149 meta-object protocol. It controls the introspection and
1150 manipulation of Perl 5 classes (and it can create them too). The
1151 best way to understand what this module can do, is to read the
1152 documentation for each of it's methods.
1156 =head2 Self Introspection
1162 This will return a B<Class::MOP::Class> instance which is related
1163 to this class. Thereby allowing B<Class::MOP::Class> to actually
1166 As with B<Class::MOP::Attribute>, B<Class::MOP> will actually
1167 bootstrap this module by installing a number of attribute meta-objects
1168 into it's metaclass. This will allow this class to reap all the benifits
1169 of the MOP when subclassing it.
1173 =head2 Class construction
1175 These methods will handle creating B<Class::MOP::Class> objects,
1176 which can be used to both create new classes, and analyze
1177 pre-existing classes.
1179 This module will internally store references to all the instances
1180 you create with these methods, so that they do not need to be
1181 created any more than nessecary. Basically, they are singletons.
1185 =item B<create ($package_name,
1186 version =E<gt> ?$version,
1187 authority =E<gt> ?$authority,
1188 superclasses =E<gt> ?@superclasses,
1189 methods =E<gt> ?%methods,
1190 attributes =E<gt> ?%attributes)>
1192 This returns a B<Class::MOP::Class> object, bringing the specified
1193 C<$package_name> into existence and adding any of the C<$version>,
1194 C<$authority>, C<@superclasses>, C<%methods> and C<%attributes> to
1197 =item B<create_anon_class (superclasses =E<gt> ?@superclasses,
1198 methods =E<gt> ?%methods,
1199 attributes =E<gt> ?%attributes)>
1201 This will create an anonymous class, it works much like C<create> but
1202 it does not need a C<$package_name>. Instead it will create a suitably
1203 unique package name for you to stash things into.
1205 On very important distinction is that anon classes are destroyed once
1206 the metaclass they are attached to goes out of scope. In the DESTROY
1207 method, the created package will be removed from the symbol table.
1209 It is also worth noting that any instances created with an anon-class
1210 will keep a special reference to the anon-meta which will prevent the
1211 anon-class from going out of scope until all instances of it have also
1212 been destroyed. This however only works for HASH based instance types,
1213 as we use a special reserved slot (C<__MOP__>) to store this.
1215 =item B<initialize ($package_name, %options)>
1217 This initializes and returns returns a B<Class::MOP::Class> object
1218 for a given a C<$package_name>.
1220 =item B<reinitialize ($package_name, %options)>
1222 This removes the old metaclass, and creates a new one in it's place.
1223 Do B<not> use this unless you really know what you are doing, it could
1224 very easily make a very large mess of your program.
1226 =item B<construct_class_instance (%options)>
1228 This will construct an instance of B<Class::MOP::Class>, it is
1229 here so that we can actually "tie the knot" for B<Class::MOP::Class>
1230 to use C<construct_instance> once all the bootstrapping is done. This
1231 method is used internally by C<initialize> and should never be called
1232 from outside of that method really.
1234 =item B<check_metaclass_compatability>
1236 This method is called as the very last thing in the
1237 C<construct_class_instance> method. This will check that the
1238 metaclass you are creating is compatible with the metaclasses of all
1239 your ancestors. For more inforamtion about metaclass compatibility
1240 see the C<About Metaclass compatibility> section in L<Class::MOP>.
1242 =item B<update_package_cache_flag>
1244 This will reset the package cache flag for this particular metaclass
1245 it is basically the value of the C<Class::MOP::get_package_cache_flag>
1246 function. This is very rarely needed from outside of C<Class::MOP::Class>
1247 but in some cases you might want to use it, so it is here.
1249 =item B<reset_package_cache_flag>
1251 Clears the package cache flag to announce to the internals that we need
1252 to rebuild the method map.
1254 =item B<add_meta_instance_dependencies>
1256 Registers this class as dependent on its superclasses.
1258 Only superclasses from which this class inherits attributes will be added.
1260 =item B<remove_meta_instance_depdendencies>
1262 Unregisters this class from its superclasses.
1264 =item B<update_meta_instance_dependencies>
1266 Reregisters if necessary.
1268 =item B<add_dependent_meta_instance> $metaclass
1270 Registers the class as having a meta instance dependent on this class.
1272 =item B<remove_dependent_meta_instance> $metaclass
1274 Remove the class from the list of dependent classes.
1276 =item B<invalidate_meta_instances>
1278 Clears the cached meta instance for this metaclass and all of the registered
1279 classes with dependent meta instances.
1281 Called by C<add_attribute> and C<remove_attribute> to recalculate the attribute
1284 =item B<invalidate_meta_instance>
1286 Used by C<invalidate_meta_instances>.
1290 =head2 Object instance construction and cloning
1292 These methods are B<entirely optional>, it is up to you whether you want
1297 =item B<instance_metaclass>
1299 Returns the class name of the instance metaclass, see L<Class::MOP::Instance>
1300 for more information on the instance metaclasses.
1302 =item B<get_meta_instance>
1304 Returns an instance of L<Class::MOP::Instance> to be used in the construction
1305 of a new instance of the class.
1307 =item B<create_meta_instance>
1309 Called by C<get_meta_instance> if necessary.
1311 =item B<new_object (%params)>
1313 This is a convience method for creating a new object of the class, and
1314 blessing it into the appropriate package as well. Ideally your class
1315 would call a C<new> this method like so:
1318 my ($class, %param) = @_;
1319 $class->meta->new_object(%params);
1322 =item B<construct_instance (%params)>
1324 This method is used to construct an instance structure suitable for
1325 C<bless>-ing into your package of choice. It works in conjunction
1326 with the Attribute protocol to collect all applicable attributes.
1328 This will construct and instance using a HASH ref as storage
1329 (currently only HASH references are supported). This will collect all
1330 the applicable attributes and layout out the fields in the HASH ref,
1331 it will then initialize them using either use the corresponding key
1332 in C<%params> or any default value or initializer found in the
1333 attribute meta-object.
1335 =item B<clone_object ($instance, %params)>
1337 This is a convience method for cloning an object instance, then
1338 blessing it into the appropriate package. This method will call
1339 C<clone_instance>, which performs a shallow copy of the object,
1340 see that methods documentation for more details. Ideally your
1341 class would call a C<clone> this method like so:
1343 sub MyClass::clone {
1344 my ($self, %param) = @_;
1345 $self->meta->clone_object($self, %params);
1348 =item B<clone_instance($instance, %params)>
1350 This method is a compliment of C<construct_instance> (which means if
1351 you override C<construct_instance>, you need to override this one too),
1352 and clones the instance shallowly.
1354 The cloned structure returned is (like with C<construct_instance>) an
1355 unC<bless>ed HASH reference, it is your responsibility to then bless
1356 this cloned structure into the right class (which C<clone_object> will
1359 As of 0.11, this method will clone the C<$instance> structure shallowly,
1360 as opposed to the deep cloning implemented in prior versions. After much
1361 thought, research and discussion, I have decided that anything but basic
1362 shallow cloning is outside the scope of the meta-object protocol. I
1363 think Yuval "nothingmuch" Kogman put it best when he said that cloning
1364 is too I<context-specific> to be part of the MOP.
1366 =item B<rebless_instance($instance, ?%params)>
1368 This will change the class of C<$instance> to the class of the invoking
1369 C<Class::MOP::Class>. You may only rebless the instance to a subclass of
1370 itself. You may pass in optional C<%params> which are like constructor
1371 params and will override anything already defined in the instance.
1375 =head2 Informational
1377 These are a few predicate methods for asking information about the class.
1381 =item B<is_anon_class>
1383 This returns true if the class is a C<Class::MOP::Class> created anon class.
1387 This returns true if the class is still mutable.
1389 =item B<is_immutable>
1391 This returns true if the class has been made immutable.
1395 =head2 Inheritance Relationships
1399 =item B<superclasses (?@superclasses)>
1401 This is a read-write attribute which represents the superclass
1402 relationships of the class the B<Class::MOP::Class> instance is
1403 associated with. Basically, it can get and set the C<@ISA> for you.
1405 =item B<class_precedence_list>
1407 This computes the a list of all the class's ancestors in the same order
1408 in which method dispatch will be done. This is similair to what
1409 B<Class::ISA::super_path> does, but we don't remove duplicate names.
1411 =item B<linearized_isa>
1413 This returns a list based on C<class_precedence_list> but with all
1418 This returns a list of subclasses for this class.
1426 =item B<get_method_map>
1428 Returns a HASH ref of name to CODE reference mapping for this class.
1430 =item B<method_metaclass>
1432 Returns the class name of the method metaclass, see L<Class::MOP::Method>
1433 for more information on the method metaclasses.
1435 =item B<add_method ($method_name, $method)>
1437 This will take a C<$method_name> and CODE reference to that
1438 C<$method> and install it into the class's package.
1441 This does absolutely nothing special to C<$method>
1442 other than use B<Sub::Name> to make sure it is tagged with the
1443 correct name, and therefore show up correctly in stack traces and
1446 =item B<alias_method ($method_name, $method)>
1448 This will take a C<$method_name> and CODE reference to that
1449 C<$method> and alias the method into the class's package.
1452 Unlike C<add_method>, this will B<not> try to name the
1453 C<$method> using B<Sub::Name>, it only aliases the method in
1454 the class's package.
1456 =item B<has_method ($method_name)>
1458 This just provides a simple way to check if the class implements
1459 a specific C<$method_name>. It will I<not> however, attempt to check
1460 if the class inherits the method (use C<UNIVERSAL::can> for that).
1462 This will correctly handle functions defined outside of the package
1463 that use a fully qualified name (C<sub Package::name { ... }>).
1465 This will correctly handle functions renamed with B<Sub::Name> and
1466 installed using the symbol tables. However, if you are naming the
1467 subroutine outside of the package scope, you must use the fully
1468 qualified name, including the package name, for C<has_method> to
1469 correctly identify it.
1471 This will attempt to correctly ignore functions imported from other
1472 packages using B<Exporter>. It breaks down if the function imported
1473 is an C<__ANON__> sub (such as with C<use constant>), which very well
1474 may be a valid method being applied to the class.
1476 In short, this method cannot always be trusted to determine if the
1477 C<$method_name> is actually a method. However, it will DWIM about
1478 90% of the time, so it's a small trade off I think.
1480 =item B<get_method ($method_name)>
1482 This will return a Class::MOP::Method instance related to the specified
1483 C<$method_name>, or return undef if that method does not exist.
1485 The Class::MOP::Method is codifiable, so you can use it like a normal
1486 CODE reference, see L<Class::MOP::Method> for more information.
1488 =item B<find_method_by_name ($method_name)>
1490 This will return a CODE reference of the specified C<$method_name>,
1491 or return undef if that method does not exist.
1493 Unlike C<get_method> this will also look in the superclasses.
1495 =item B<remove_method ($method_name)>
1497 This will attempt to remove a given C<$method_name> from the class.
1498 It will return the CODE reference that it has removed, and will
1499 attempt to use B<Sub::Name> to clear the methods associated name.
1501 =item B<get_method_list>
1503 This will return a list of method names for all I<locally> defined
1504 methods. It does B<not> provide a list of all applicable methods,
1505 including any inherited ones. If you want a list of all applicable
1506 methods, use the C<compute_all_applicable_methods> method.
1508 =item B<get_all_methods>
1510 This will traverse the inheritance heirachy and return a list of all
1511 the applicable L<Class::MOP::Method> objects for this class.
1513 =item B<compute_all_applicable_methods>
1517 This method returns a list of hashes describing the all the methods of the
1520 Use L<get_all_methods>, which is easier/better/faster. This method predates
1521 L<Class::MOP::Method>.
1523 =item B<find_all_methods_by_name ($method_name)>
1525 This will traverse the inheritence hierarchy and locate all methods
1526 with a given C<$method_name>. Similar to
1527 C<compute_all_applicable_methods> it returns a list of HASH references
1528 with the following information; method name (which will always be the
1529 same as C<$method_name>), the name of the class in which the method
1530 lives and a CODE reference for the actual method.
1532 The list of methods produced is a distinct list, meaning there are no
1533 duplicates in it. This is especially useful for things like object
1534 initialization and destruction where you only want the method called
1535 once, and in the correct order.
1537 =item B<find_next_method_by_name ($method_name)>
1539 This will return the first method to match a given C<$method_name> in
1540 the superclasses, this is basically equivalent to calling
1541 C<SUPER::$method_name>, but it can be dispatched at runtime.
1545 =head2 Method Modifiers
1547 Method modifiers are a concept borrowed from CLOS, in which a method
1548 can be wrapped with I<before>, I<after> and I<around> method modifiers
1549 that will be called everytime the method is called.
1551 =head3 How method modifiers work?
1553 Method modifiers work by wrapping the original method and then replacing
1554 it in the classes symbol table. The wrappers will handle calling all the
1555 modifiers in the appropariate orders and preserving the calling context
1556 for the original method.
1558 Each method modifier serves a particular purpose, which may not be
1559 obvious to users of other method wrapping modules. To start with, the
1560 return values of I<before> and I<after> modifiers are ignored. This is
1561 because thier purpose is B<not> to filter the input and output of the
1562 primary method (this is done with an I<around> modifier). This may seem
1563 like an odd restriction to some, but doing this allows for simple code
1564 to be added at the begining or end of a method call without jeapordizing
1565 the normal functioning of the primary method or placing any extra
1566 responsibility on the code of the modifier. Of course if you have more
1567 complex needs, then use the I<around> modifier, which uses a variation
1568 of continutation passing style to allow for a high degree of flexibility.
1570 Before and around modifiers are called in last-defined-first-called order,
1571 while after modifiers are called in first-defined-first-called order. So
1572 the call tree might looks something like this:
1582 To see examples of using method modifiers, see the following examples
1583 included in the distribution; F<InstanceCountingClass>, F<Perl6Attribute>,
1584 F<AttributesWithHistory> and F<C3MethodDispatchOrder>. There is also a
1585 classic CLOS usage example in the test F<017_add_method_modifier.t>.
1587 =head3 What is the performance impact?
1589 Of course there is a performance cost associated with method modifiers,
1590 but we have made every effort to make that cost be directly proportional
1591 to the amount of modifier features you utilize.
1593 The wrapping method does it's best to B<only> do as much work as it
1594 absolutely needs to. In order to do this we have moved some of the
1595 performance costs to set-up time, where they are easier to amortize.
1597 All this said, my benchmarks have indicated the following:
1599 simple wrapper with no modifiers 100% slower
1600 simple wrapper with simple before modifier 400% slower
1601 simple wrapper with simple after modifier 450% slower
1602 simple wrapper with simple around modifier 500-550% slower
1603 simple wrapper with all 3 modifiers 1100% slower
1605 These numbers may seem daunting, but you must remember, every feature
1606 comes with some cost. To put things in perspective, just doing a simple
1607 C<AUTOLOAD> which does nothing but extract the name of the method called
1608 and return it costs about 400% over a normal method call.
1612 =item B<add_before_method_modifier ($method_name, $code)>
1614 This will wrap the method at C<$method_name> and the supplied C<$code>
1615 will be passed the C<@_> arguments, and called before the original
1616 method is called. As specified above, the return value of the I<before>
1617 method modifiers is ignored, and it's ability to modify C<@_> is
1618 fairly limited. If you need to do either of these things, use an
1619 C<around> method modifier.
1621 =item B<add_after_method_modifier ($method_name, $code)>
1623 This will wrap the method at C<$method_name> so that the original
1624 method will be called, it's return values stashed, and then the
1625 supplied C<$code> will be passed the C<@_> arguments, and called.
1626 As specified above, the return value of the I<after> method
1627 modifiers is ignored, and it cannot modify the return values of
1628 the original method. If you need to do either of these things, use an
1629 C<around> method modifier.
1631 =item B<add_around_method_modifier ($method_name, $code)>
1633 This will wrap the method at C<$method_name> so that C<$code>
1634 will be called and passed the original method as an extra argument
1635 at the begining of the C<@_> argument list. This is a variation of
1636 continuation passing style, where the function prepended to C<@_>
1637 can be considered a continuation. It is up to C<$code> if it calls
1638 the original method or not, there is no restriction on what the
1639 C<$code> can or cannot do.
1645 It should be noted that since there is no one consistent way to define
1646 the attributes of a class in Perl 5. These methods can only work with
1647 the information given, and can not easily discover information on
1648 their own. See L<Class::MOP::Attribute> for more details.
1652 =item B<attribute_metaclass>
1654 Returns the class name of the attribute metaclass, see L<Class::MOP::Attribute>
1655 for more information on the attribute metaclasses.
1657 =item B<get_attribute_map>
1659 This returns a HASH ref of name to attribute meta-object mapping.
1661 =item B<add_attribute ($attribute_meta_object | ($attribute_name, %attribute_spec))>
1663 This stores the C<$attribute_meta_object> (or creates one from the
1664 C<$attribute_name> and C<%attribute_spec>) in the B<Class::MOP::Class>
1665 instance associated with the given class. Unlike methods, attributes
1666 within the MOP are stored as meta-information only. They will be used
1667 later to construct instances from (see C<construct_instance> above).
1668 More details about the attribute meta-objects can be found in the
1669 L<Class::MOP::Attribute> or the L<Class::MOP/The Attribute protocol>
1672 It should be noted that any accessor, reader/writer or predicate
1673 methods which the C<$attribute_meta_object> has will be installed
1674 into the class at this time.
1677 If an attribute already exists for C<$attribute_name>, the old one
1678 will be removed (as well as removing all it's accessors), and then
1681 =item B<has_attribute ($attribute_name)>
1683 Checks to see if this class has an attribute by the name of
1684 C<$attribute_name> and returns a boolean.
1686 =item B<get_attribute ($attribute_name)>
1688 Returns the attribute meta-object associated with C<$attribute_name>,
1689 if none is found, it will return undef.
1691 =item B<remove_attribute ($attribute_name)>
1693 This will remove the attribute meta-object stored at
1694 C<$attribute_name>, then return the removed attribute meta-object.
1697 Removing an attribute will only affect future instances of
1698 the class, it will not make any attempt to remove the attribute from
1699 any existing instances of the class.
1701 It should be noted that any accessor, reader/writer or predicate
1702 methods which the attribute meta-object stored at C<$attribute_name>
1703 has will be removed from the class at this time. This B<will> make
1704 these attributes somewhat inaccessable in previously created
1705 instances. But if you are crazy enough to do this at runtime, then
1706 you are crazy enough to deal with something like this :).
1708 =item B<get_attribute_list>
1710 This returns a list of attribute names which are defined in the local
1711 class. If you want a list of all applicable attributes for a class,
1712 use the C<compute_all_applicable_attributes> method.
1714 =item B<compute_all_applicable_attributes>
1716 =item B<get_all_attributes>
1718 This will traverse the inheritance heirachy and return a list of all
1719 the applicable L<Class::MOP::Attribute> objects for this class.
1721 C<get_all_attributes> is an alias for consistency with C<get_all_methods>.
1723 =item B<find_attribute_by_name ($attr_name)>
1725 This method will traverse the inheritance heirachy and find the
1726 first attribute whose name matches C<$attr_name>, then return it.
1727 It will return undef if nothing is found.
1731 =head2 Class Immutability
1735 =item B<make_immutable (%options)>
1737 This method will invoke a tranforamtion upon the class which will
1738 make it immutable. Details of this transformation can be found in
1739 the L<Class::MOP::Immutable> documentation.
1741 =item B<make_mutable>
1743 This method will reverse tranforamtion upon the class which
1746 =item B<get_immutable_transformer>
1748 Return a transformer suitable for making this class immutable or, if this
1749 class is immutable, the transformer used to make it immutable.
1751 =item B<get_immutable_options>
1753 If the class is immutable, return the options used to make it immutable.
1755 =item B<create_immutable_transformer>
1757 Create a transformer suitable for making this class immutable
1763 Stevan Little E<lt>stevan@iinteractive.comE<gt>
1765 =head1 COPYRIGHT AND LICENSE
1767 Copyright 2006-2008 by Infinity Interactive, Inc.
1769 L<http://www.iinteractive.com>
1771 This library is free software; you can redistribute it and/or modify
1772 it under the same terms as Perl itself.