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, @_);
40 # NOTE: (meta-circularity)
41 # this is a special form of &construct_instance
42 # (see below), which is used to construct class
43 # meta-object instances for any Class::MOP::*
44 # class. All other classes will use the more
45 # normal &construct_instance.
46 sub construct_class_instance {
48 my $options = @_ == 1 ? $_[0] : {@_};
49 my $package_name = $options->{package};
50 (defined $package_name && $package_name)
51 || confess "You must pass a package name";
53 # return the metaclass if we have it cached,
54 # and it is still defined (it has not been
55 # reaped by DESTROY yet, which can happen
56 # annoyingly enough during global destruction)
58 if (defined(my $meta = Class::MOP::get_metaclass_by_name($package_name))) {
63 # we need to deal with the possibility
64 # of class immutability here, and then
65 # get the name of the class appropriately
67 ? ($class->is_immutable
68 ? $class->get_mutable_metaclass_name()
72 # now create the metaclass
74 if ($class eq 'Class::MOP::Class') {
76 $meta = $class->_new($options)
80 # it is safe to use meta here because
81 # class will always be a subclass of
82 # Class::MOP::Class, which defines meta
83 $meta = $class->meta->construct_instance($options)
86 # and check the metaclass compatibility
87 $meta->check_metaclass_compatability();
89 Class::MOP::store_metaclass_by_name($package_name, $meta);
92 # we need to weaken any anon classes
93 # so that they can call DESTROY properly
94 Class::MOP::weaken_metaclass($package_name) if $meta->is_anon_class;
101 my $options = @_ == 1 ? $_[0] : {@_};
104 # inherited from Class::MOP::Package
105 'package' => $options->{package},
108 # since the following attributes will
109 # actually be loaded from the symbol
110 # table, and actually bypass the instance
111 # entirely, we can just leave these things
112 # listed here for reference, because they
113 # should not actually have a value associated
115 'namespace' => \undef,
116 # inherited from Class::MOP::Module
118 'authority' => \undef,
119 # defined in Class::MOP::Class
120 'superclasses' => \undef,
124 'attribute_metaclass' => $options->{'attribute_metaclass'} || 'Class::MOP::Attribute',
125 'method_metaclass' => $options->{'method_metaclass'} || 'Class::MOP::Method',
126 'instance_metaclass' => $options->{'instance_metaclass'} || 'Class::MOP::Instance',
130 sub reset_package_cache_flag { (shift)->{'_package_cache_flag'} = undef }
131 sub update_package_cache_flag {
134 # we can manually update the cache number
135 # since we are actually adding the method
136 # to our cache as well. This avoids us
137 # having to regenerate the method_map.
139 $self->{'_package_cache_flag'} = Class::MOP::check_package_cache_flag($self->name);
142 sub check_metaclass_compatability {
145 # this is always okay ...
146 return if ref($self) eq 'Class::MOP::Class' &&
147 $self->instance_metaclass eq 'Class::MOP::Instance';
149 my @class_list = $self->linearized_isa;
150 shift @class_list; # shift off $self->name
152 foreach my $class_name (@class_list) {
153 my $meta = Class::MOP::get_metaclass_by_name($class_name) || next;
156 # we need to deal with the possibility
157 # of class immutability here, and then
158 # get the name of the class appropriately
159 my $meta_type = ($meta->is_immutable
160 ? $meta->get_mutable_metaclass_name()
163 ($self->isa($meta_type))
164 || confess $self->name . "->meta => (" . (ref($self)) . ")" .
165 " is not compatible with the " .
166 $class_name . "->meta => (" . ($meta_type) . ")";
168 # we also need to check that instance metaclasses
169 # are compatabile in the same the class.
170 ($self->instance_metaclass->isa($meta->instance_metaclass))
171 || confess $self->name . "->meta => (" . ($self->instance_metaclass) . ")" .
172 " is not compatible with the " .
173 $class_name . "->meta => (" . ($meta->instance_metaclass) . ")";
181 # this should be sufficient, if you have a
182 # use case where it is not, write a test and
184 my $ANON_CLASS_SERIAL = 0;
187 # we need a sufficiently annoying prefix
188 # this should suffice for now, this is
189 # used in a couple of places below, so
190 # need to put it up here for now.
191 my $ANON_CLASS_PREFIX = 'Class::MOP::Class::__ANON__::SERIAL::';
195 no warnings 'uninitialized';
196 $self->name =~ /^$ANON_CLASS_PREFIX/;
199 sub create_anon_class {
200 my ($class, %options) = @_;
201 my $package_name = $ANON_CLASS_PREFIX . ++$ANON_CLASS_SERIAL;
202 return $class->create($package_name, %options);
206 # this will only get called for
207 # anon-classes, all other calls
208 # are assumed to occur during
209 # global destruction and so don't
210 # really need to be handled explicitly
214 return if Class::MOP::in_global_destruction; # it'll happen soon anyway and this just makes things more complicated
216 no warnings 'uninitialized';
217 return unless $self->name =~ /^$ANON_CLASS_PREFIX/;
218 my ($serial_id) = ($self->name =~ /^$ANON_CLASS_PREFIX(\d+)/);
220 foreach my $key (keys %{$ANON_CLASS_PREFIX . $serial_id}) {
221 delete ${$ANON_CLASS_PREFIX . $serial_id}{$key};
223 delete ${'main::' . $ANON_CLASS_PREFIX}{$serial_id . '::'};
228 # creating classes with MOP ...
231 my ( $class, @args ) = @_;
233 unshift @args, 'package' if @args % 2 == 1;
235 my (%options) = @args;
236 my $package_name = $options{package};
238 (defined $package_name && $package_name)
239 || confess "You must pass a package name";
241 (ref $options{superclasses} eq 'ARRAY')
242 || confess "You must pass an ARRAY ref of superclasses"
243 if exists $options{superclasses};
245 (ref $options{attributes} eq 'ARRAY')
246 || confess "You must pass an ARRAY ref of attributes"
247 if exists $options{attributes};
249 (ref $options{methods} eq 'HASH')
250 || confess "You must pass an HASH ref of methods"
251 if exists $options{methods};
253 my $code = "package $package_name;";
254 $code .= "\$$package_name\:\:VERSION = '" . $options{version} . "';"
255 if exists $options{version};
256 $code .= "\$$package_name\:\:AUTHORITY = '" . $options{authority} . "';"
257 if exists $options{authority};
260 confess "creation of $package_name failed : $@" if $@;
262 my $meta = $class->initialize($package_name);
265 $meta->add_method('meta' => sub {
266 $class->initialize(ref($_[0]) || $_[0]);
269 $meta->superclasses(@{$options{superclasses}})
270 if exists $options{superclasses};
272 # process attributes first, so that they can
273 # install accessors, but locally defined methods
274 # can then overwrite them. It is maybe a little odd, but
275 # I think this should be the order of things.
276 if (exists $options{attributes}) {
277 foreach my $attr (@{$options{attributes}}) {
278 $meta->add_attribute($attr);
281 if (exists $options{methods}) {
282 foreach my $method_name (keys %{$options{methods}}) {
283 $meta->add_method($method_name, $options{methods}->{$method_name});
292 # all these attribute readers will be bootstrapped
293 # away in the Class::MOP bootstrap section
295 sub get_attribute_map { $_[0]->{'attributes'} }
296 sub attribute_metaclass { $_[0]->{'attribute_metaclass'} }
297 sub method_metaclass { $_[0]->{'method_metaclass'} }
298 sub instance_metaclass { $_[0]->{'instance_metaclass'} }
301 # this is a prime canidate for conversion to XS
305 my $current = Class::MOP::check_package_cache_flag($self->name);
307 if (defined $self->{'_package_cache_flag'} && $self->{'_package_cache_flag'} == $current) {
308 return $self->{'methods'} ||= {};
311 $self->{_package_cache_flag} = $current;
313 my $map = $self->{'methods'} ||= {};
315 my $class_name = $self->name;
316 my $method_metaclass = $self->method_metaclass;
318 my %all_code = $self->get_all_package_symbols('CODE');
320 foreach my $symbol (keys %all_code) {
321 my $code = $all_code{$symbol};
323 next if exists $map->{$symbol} &&
324 defined $map->{$symbol} &&
325 $map->{$symbol}->body == $code;
327 my ($pkg, $name) = Class::MOP::get_code_info($code);
330 # in 5.10 constant.pm the constants show up
331 # as being in the right package, but in pre-5.10
332 # they show up as constant::__ANON__ so we
333 # make an exception here to be sure that things
334 # work as expected in both.
336 unless ($pkg eq 'constant' && $name eq '__ANON__') {
337 next if ($pkg || '') ne $class_name ||
338 (($name || '') ne '__ANON__' && ($pkg || '') ne $class_name);
341 $map->{$symbol} = $method_metaclass->wrap(
343 associated_metaclass => $self,
344 package_name => $class_name,
352 # Instance Construction & Cloning
358 # we need to protect the integrity of the
359 # Class::MOP::Class singletons here, so we
360 # delegate this to &construct_class_instance
361 # which will deal with the singletons
362 return $class->construct_class_instance(@_)
363 if $class->name->isa('Class::MOP::Class');
364 return $class->construct_instance(@_);
367 sub construct_instance {
369 my $params = @_ == 1 ? $_[0] : {@_};
370 my $meta_instance = $class->get_meta_instance();
371 my $instance = $meta_instance->create_instance();
372 foreach my $attr ($class->compute_all_applicable_attributes()) {
373 $attr->initialize_instance_slot($meta_instance, $instance, $params);
376 # this will only work for a HASH instance type
377 if ($class->is_anon_class) {
378 (Scalar::Util::reftype($instance) eq 'HASH')
379 || confess "Currently only HASH based instances are supported with instance of anon-classes";
381 # At some point we should make this official
382 # as a reserved slot name, but right now I am
383 # going to keep it here.
384 # my $RESERVED_MOP_SLOT = '__MOP__';
385 $instance->{'__MOP__'} = $class;
391 sub get_meta_instance {
393 $self->{'_meta_instance'} ||= $self->create_meta_instance();
396 sub create_meta_instance {
399 my $instance = $self->instance_metaclass->new(
400 associated_metaclass => $self,
401 attributes => [ $self->compute_all_applicable_attributes() ],
404 $self->add_meta_instance_dependencies()
405 if $instance->is_dependent_on_superclasses();
412 my $instance = shift;
413 (blessed($instance) && $instance->isa($class->name))
414 || confess "You must pass an instance of the metaclass (" . (ref $class ? $class->name : $class) . "), not ($instance)";
417 # we need to protect the integrity of the
418 # Class::MOP::Class singletons here, they
419 # should not be cloned.
420 return $instance if $instance->isa('Class::MOP::Class');
421 $class->clone_instance($instance, @_);
425 my ($class, $instance, %params) = @_;
427 || confess "You can only clone instances, ($instance) is not a blessed instance";
428 my $meta_instance = $class->get_meta_instance();
429 my $clone = $meta_instance->clone_instance($instance);
430 foreach my $attr ($class->compute_all_applicable_attributes()) {
431 if ( defined( my $init_arg = $attr->init_arg ) ) {
432 if (exists $params{$init_arg}) {
433 $attr->set_value($clone, $params{$init_arg});
440 sub rebless_instance {
441 my ($self, $instance, %params) = @_;
444 if ($instance->can('meta')) {
445 ($instance->meta->isa('Class::MOP::Class'))
446 || confess 'Cannot rebless instance if ->meta is not an instance of Class::MOP::Class';
447 $old_metaclass = $instance->meta;
450 $old_metaclass = $self->initialize(ref($instance));
453 my $meta_instance = $self->get_meta_instance();
455 $self->name->isa($old_metaclass->name)
456 || confess "You may rebless only into a subclass of (". $old_metaclass->name ."), of which (". $self->name .") isn't.";
459 $meta_instance->rebless_instance_structure($instance, $self);
461 foreach my $attr ( $self->compute_all_applicable_attributes ) {
462 if ( $attr->has_value($instance) ) {
463 if ( defined( my $init_arg = $attr->init_arg ) ) {
464 $params{$init_arg} = $attr->get_value($instance)
465 unless exists $params{$init_arg};
468 $attr->set_value($instance, $attr->get_value($instance));
473 foreach my $attr ($self->compute_all_applicable_attributes) {
474 $attr->initialize_instance_slot($meta_instance, $instance, \%params);
484 my $var_spec = { sigil => '@', type => 'ARRAY', name => 'ISA' };
487 @{$self->get_package_symbol($var_spec)} = @supers;
489 # we need to check the metaclass
490 # compatibility here so that we can
491 # be sure that the superclass is
492 # not potentially creating an issues
493 # we don't know about
494 $self->check_metaclass_compatability();
495 $self->update_meta_instance_dependencies();
497 @{$self->get_package_symbol($var_spec)};
503 my $super_class = $self->name;
505 if ( Class::MOP::HAVE_ISAREV() ) {
506 return @{ $super_class->mro::get_isarev() };
510 my $find_derived_classes;
511 $find_derived_classes = sub {
512 my ($outer_class) = @_;
514 my $symbol_table_hashref = do { no strict 'refs'; \%{"${outer_class}::"} };
517 for my $symbol ( keys %$symbol_table_hashref ) {
518 next SYMBOL if $symbol !~ /\A (\w+):: \z/x;
519 my $inner_class = $1;
521 next SYMBOL if $inner_class eq 'SUPER'; # skip '*::SUPER'
525 ? "${outer_class}::$inner_class"
528 if ( $class->isa($super_class) and $class ne $super_class ) {
529 push @derived_classes, $class;
532 next SYMBOL if $class eq 'main'; # skip 'main::*'
534 $find_derived_classes->($class);
538 my $root_class = q{};
539 $find_derived_classes->($root_class);
541 undef $find_derived_classes;
543 @derived_classes = sort { $a->isa($b) ? 1 : $b->isa($a) ? -1 : 0 } @derived_classes;
545 return @derived_classes;
551 return @{ mro::get_linear_isa( (shift)->name ) };
554 sub class_precedence_list {
556 my $name = $self->name;
558 unless (Class::MOP::IS_RUNNING_ON_5_10()) {
560 # We need to check for circular inheritance here
561 # if we are are not on 5.10, cause 5.8 detects it
562 # late. This will do nothing if all is well, and
563 # blow up otherwise. Yes, it's an ugly hack, better
564 # suggestions are welcome.
566 ($name || return)->isa('This is a test for circular inheritance')
569 # if our mro is c3, we can
570 # just grab the linear_isa
571 if (mro::get_mro($name) eq 'c3') {
572 return @{ mro::get_linear_isa($name) }
576 # we can't grab the linear_isa for dfs
577 # since it has all the duplicates
582 $self->initialize($_)->class_precedence_list()
583 } $self->superclasses()
591 my ($self, $method_name, $method) = @_;
592 (defined $method_name && $method_name)
593 || confess "You must define a method name";
596 if (blessed($method)) {
597 $body = $method->body;
598 if ($method->package_name ne $self->name &&
599 $method->name ne $method_name) {
600 warn "Hello there, got something for you."
601 . " Method says " . $method->package_name . " " . $method->name
602 . " Class says " . $self->name . " " . $method_name;
603 $method = $method->clone(
604 package_name => $self->name,
606 ) if $method->can('clone');
611 ('CODE' eq ref($body))
612 || confess "Your code block must be a CODE reference";
613 $method = $self->method_metaclass->wrap(
615 package_name => $self->name,
621 $method->attach_to_class($self);
623 $self->get_method_map->{$method_name} = $method;
625 my $full_method_name = ($self->name . '::' . $method_name);
626 $self->add_package_symbol(
627 { sigil => '&', type => 'CODE', name => $method_name },
628 Class::MOP::subname($full_method_name => $body)
631 $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
635 my $fetch_and_prepare_method = sub {
636 my ($self, $method_name) = @_;
638 my $method = $self->get_method($method_name);
639 # if we dont have local ...
641 # try to find the next method
642 $method = $self->find_next_method_by_name($method_name);
643 # die if it does not exist
645 || confess "The method '$method_name' is not found in the inheritance hierarchy for class " . $self->name;
646 # and now make sure to wrap it
647 # even if it is already wrapped
648 # because we need a new sub ref
649 $method = Class::MOP::Method::Wrapped->wrap($method);
652 # now make sure we wrap it properly
653 $method = Class::MOP::Method::Wrapped->wrap($method)
654 unless $method->isa('Class::MOP::Method::Wrapped');
656 $self->add_method($method_name => $method);
660 sub add_before_method_modifier {
661 my ($self, $method_name, $method_modifier) = @_;
662 (defined $method_name && $method_name)
663 || confess "You must pass in a method name";
664 my $method = $fetch_and_prepare_method->($self, $method_name);
665 $method->add_before_modifier(
666 Class::MOP::subname(':before' => $method_modifier)
670 sub add_after_method_modifier {
671 my ($self, $method_name, $method_modifier) = @_;
672 (defined $method_name && $method_name)
673 || confess "You must pass in a method name";
674 my $method = $fetch_and_prepare_method->($self, $method_name);
675 $method->add_after_modifier(
676 Class::MOP::subname(':after' => $method_modifier)
680 sub add_around_method_modifier {
681 my ($self, $method_name, $method_modifier) = @_;
682 (defined $method_name && $method_name)
683 || confess "You must pass in a method name";
684 my $method = $fetch_and_prepare_method->($self, $method_name);
685 $method->add_around_modifier(
686 Class::MOP::subname(':around' => $method_modifier)
691 # the methods above used to be named like this:
692 # ${pkg}::${method}:(before|after|around)
693 # but this proved problematic when using one modifier
694 # to wrap multiple methods (something which is likely
695 # to happen pretty regularly IMO). So instead of naming
696 # it like this, I have chosen to just name them purely
697 # with their modifier names, like so:
698 # :(before|after|around)
699 # The fact is that in a stack trace, it will be fairly
700 # evident from the context what method they are attached
701 # to, and so don't need the fully qualified name.
705 my ($self, $method_name, $method) = @_;
706 (defined $method_name && $method_name)
707 || confess "You must define a method name";
709 my $body = (blessed($method) ? $method->body : $method);
710 ('CODE' eq ref($body))
711 || confess "Your code block must be a CODE reference";
713 $self->add_package_symbol(
714 { sigil => '&', type => 'CODE', name => $method_name } => $body
719 my ($self, $method_name) = @_;
720 (defined $method_name && $method_name)
721 || confess "You must define a method name";
723 return 0 unless exists $self->get_method_map->{$method_name};
728 my ($self, $method_name) = @_;
729 (defined $method_name && $method_name)
730 || confess "You must define a method name";
733 # I don't really need this here, because
734 # if the method_map is missing a key it
735 # will just return undef for me now
736 # return unless $self->has_method($method_name);
738 return $self->get_method_map->{$method_name};
742 my ($self, $method_name) = @_;
743 (defined $method_name && $method_name)
744 || confess "You must define a method name";
746 my $removed_method = delete $self->get_method_map->{$method_name};
748 $self->remove_package_symbol(
749 { sigil => '&', type => 'CODE', name => $method_name }
752 $removed_method->detach_from_class if $removed_method;
754 $self->update_package_cache_flag; # still valid, since we just removed the method from the map
756 return $removed_method;
759 sub get_method_list {
761 keys %{$self->get_method_map};
764 sub find_method_by_name {
765 my ($self, $method_name) = @_;
766 (defined $method_name && $method_name)
767 || confess "You must define a method name to find";
768 foreach my $class ($self->linearized_isa) {
769 # fetch the meta-class ...
770 my $meta = $self->initialize($class);
771 return $meta->get_method($method_name)
772 if $meta->has_method($method_name);
777 sub get_all_methods {
779 my %methods = map { %{ $self->initialize($_)->get_method_map } } reverse $self->linearized_isa;
780 return values %methods;
784 sub compute_all_applicable_methods {
788 class => $_->package_name,
789 code => $_, # sigh, overloading
791 } shift->get_all_methods(@_);
794 sub find_all_methods_by_name {
795 my ($self, $method_name) = @_;
796 (defined $method_name && $method_name)
797 || confess "You must define a method name to find";
799 foreach my $class ($self->linearized_isa) {
800 # fetch the meta-class ...
801 my $meta = $self->initialize($class);
803 name => $method_name,
805 code => $meta->get_method($method_name)
806 } if $meta->has_method($method_name);
811 sub find_next_method_by_name {
812 my ($self, $method_name) = @_;
813 (defined $method_name && $method_name)
814 || confess "You must define a method name to find";
815 my @cpl = $self->linearized_isa;
816 shift @cpl; # discard ourselves
817 foreach my $class (@cpl) {
818 # fetch the meta-class ...
819 my $meta = $self->initialize($class);
820 return $meta->get_method($method_name)
821 if $meta->has_method($method_name);
830 # either we have an attribute object already
831 # or we need to create one from the args provided
832 my $attribute = blessed($_[0]) ? $_[0] : $self->attribute_metaclass->new(@_);
833 # make sure it is derived from the correct type though
834 ($attribute->isa('Class::MOP::Attribute'))
835 || confess "Your attribute must be an instance of Class::MOP::Attribute (or a subclass)";
837 # first we attach our new attribute
838 # because it might need certain information
839 # about the class which it is attached to
840 $attribute->attach_to_class($self);
842 # then we remove attributes of a conflicting
843 # name here so that we can properly detach
844 # the old attr object, and remove any
845 # accessors it would have generated
846 if ( $self->has_attribute($attribute->name) ) {
847 $self->remove_attribute($attribute->name);
849 $self->invalidate_meta_instances();
852 # then onto installing the new accessors
853 $self->get_attribute_map->{$attribute->name} = $attribute;
855 # invalidate package flag here
856 my $e = do { local $@; eval { $attribute->install_accessors() }; $@ };
858 $self->remove_attribute($attribute->name);
865 sub update_meta_instance_dependencies {
868 if ( $self->{meta_instance_dependencies} ) {
869 return $self->add_meta_instance_dependencies;
873 sub add_meta_instance_dependencies {
876 $self->remove_meta_instance_depdendencies;
878 my @attrs = $self->compute_all_applicable_attributes();
881 my @classes = grep { not $seen{$_->name}++ } map { $_->associated_class } @attrs;
883 foreach my $class ( @classes ) {
884 $class->add_dependent_meta_instance($self);
887 $self->{meta_instance_dependencies} = \@classes;
890 sub remove_meta_instance_depdendencies {
893 if ( my $classes = delete $self->{meta_instance_dependencies} ) {
894 foreach my $class ( @$classes ) {
895 $class->remove_dependent_meta_instance($self);
905 sub add_dependent_meta_instance {
906 my ( $self, $metaclass ) = @_;
907 push @{ $self->{dependent_meta_instances} }, $metaclass;
910 sub remove_dependent_meta_instance {
911 my ( $self, $metaclass ) = @_;
912 my $name = $metaclass->name;
913 @$_ = grep { $_->name ne $name } @$_ for $self->{dependent_meta_instances};
916 sub invalidate_meta_instances {
918 $_->invalidate_meta_instance() for $self, @{ $self->{dependent_meta_instances} };
921 sub invalidate_meta_instance {
923 undef $self->{_meta_instance};
927 my ($self, $attribute_name) = @_;
928 (defined $attribute_name && $attribute_name)
929 || confess "You must define an attribute name";
930 exists $self->get_attribute_map->{$attribute_name};
934 my ($self, $attribute_name) = @_;
935 (defined $attribute_name && $attribute_name)
936 || confess "You must define an attribute name";
937 return $self->get_attribute_map->{$attribute_name}
939 # this will return undef anyway, so no need ...
940 # if $self->has_attribute($attribute_name);
944 sub remove_attribute {
945 my ($self, $attribute_name) = @_;
946 (defined $attribute_name && $attribute_name)
947 || confess "You must define an attribute name";
948 my $removed_attribute = $self->get_attribute_map->{$attribute_name};
949 return unless defined $removed_attribute;
950 delete $self->get_attribute_map->{$attribute_name};
951 $self->invalidate_meta_instances();
952 $removed_attribute->remove_accessors();
953 $removed_attribute->detach_from_class();
954 return $removed_attribute;
957 sub get_attribute_list {
959 keys %{$self->get_attribute_map};
962 sub get_all_attributes {
963 shift->compute_all_applicable_attributes(@_);
966 sub compute_all_applicable_attributes {
968 my %attrs = map { %{ $self->initialize($_)->get_attribute_map } } reverse $self->linearized_isa;
969 return values %attrs;
972 sub find_attribute_by_name {
973 my ($self, $attr_name) = @_;
974 foreach my $class ($self->linearized_isa) {
975 # fetch the meta-class ...
976 my $meta = $self->initialize($class);
977 return $meta->get_attribute($attr_name)
978 if $meta->has_attribute($attr_name);
986 sub is_immutable { 0 }
989 # Why I changed this (groditi)
990 # - One Metaclass may have many Classes through many Metaclass instances
991 # - One Metaclass should only have one Immutable Transformer instance
992 # - Each Class may have different Immutabilizing options
993 # - Therefore each Metaclass instance may have different Immutabilizing options
994 # - We need to store one Immutable Transformer instance per Metaclass
995 # - We need to store one set of Immutable Transformer options per Class
996 # - Upon make_mutable we may delete the Immutabilizing options
997 # - We could clean the immutable Transformer instance when there is no more
998 # immutable Classes of that type, but we can also keep it in case
999 # another class with this same Metaclass becomes immutable. It is a case
1000 # of trading of storing an instance to avoid unnecessary instantiations of
1001 # Immutable Transformers. You may view this as a memory leak, however
1002 # Because we have few Metaclasses, in practice it seems acceptable
1003 # - To allow Immutable Transformers instances to be cleaned up we could weaken
1004 # the reference stored in $IMMUTABLE_TRANSFORMERS{$class} and ||= should DWIM
1008 my %IMMUTABLE_TRANSFORMERS;
1009 my %IMMUTABLE_OPTIONS;
1011 sub get_immutable_options {
1013 return if $self->is_mutable;
1014 confess "unable to find immutabilizing options"
1015 unless exists $IMMUTABLE_OPTIONS{$self->name};
1016 my %options = %{$IMMUTABLE_OPTIONS{$self->name}};
1017 delete $options{IMMUTABLE_TRANSFORMER};
1021 sub get_immutable_transformer {
1023 if( $self->is_mutable ){
1024 my $class = ref $self || $self;
1025 return $IMMUTABLE_TRANSFORMERS{$class} ||= $self->create_immutable_transformer;
1027 confess "unable to find transformer for immutable class"
1028 unless exists $IMMUTABLE_OPTIONS{$self->name};
1029 return $IMMUTABLE_OPTIONS{$self->name}->{IMMUTABLE_TRANSFORMER};
1032 sub make_immutable {
1036 my $transformer = $self->get_immutable_transformer;
1037 $transformer->make_metaclass_immutable($self, \%options);
1038 $IMMUTABLE_OPTIONS{$self->name} =
1039 { %options, IMMUTABLE_TRANSFORMER => $transformer };
1041 if( exists $options{debug} && $options{debug} ){
1042 print STDERR "# of Metaclass options: ", keys %IMMUTABLE_OPTIONS;
1043 print STDERR "# of Immutable transformers: ", keys %IMMUTABLE_TRANSFORMERS;
1051 return if $self->is_mutable;
1052 my $options = delete $IMMUTABLE_OPTIONS{$self->name};
1053 confess "unable to find immutabilizing options" unless ref $options;
1054 my $transformer = delete $options->{IMMUTABLE_TRANSFORMER};
1055 $transformer->make_metaclass_mutable($self, $options);
1060 sub create_immutable_transformer {
1062 my $class = Class::MOP::Immutable->new($self, {
1063 read_only => [qw/superclasses/],
1070 remove_package_symbol
1073 class_precedence_list => 'ARRAY',
1074 linearized_isa => 'ARRAY',
1075 compute_all_applicable_attributes => 'ARRAY',
1076 get_meta_instance => 'SCALAR',
1077 get_method_map => 'SCALAR',
1080 # this is ugly, but so are typeglobs,
1081 # so whattayahgonnadoboutit
1084 add_package_symbol => sub {
1085 my $original = shift;
1086 confess "Cannot add package symbols to an immutable metaclass"
1087 unless (caller(2))[3] eq 'Class::MOP::Package::get_package_symbol';
1088 goto $original->body;
1103 Class::MOP::Class - Class Meta Object
1107 # assuming that class Foo
1108 # has been defined, you can
1110 # use this for introspection ...
1112 # add a method to Foo ...
1113 Foo->meta->add_method('bar' => sub { ... })
1115 # get a list of all the classes searched
1116 # the method dispatcher in the correct order
1117 Foo->meta->class_precedence_list()
1119 # remove a method from Foo
1120 Foo->meta->remove_method('bar');
1122 # or use this to actually create classes ...
1124 Class::MOP::Class->create('Bar' => (
1126 superclasses => [ 'Foo' ],
1128 Class::MOP:::Attribute->new('$bar'),
1129 Class::MOP:::Attribute->new('$baz'),
1132 calculate_bar => sub { ... },
1133 construct_baz => sub { ... }
1139 This is the largest and currently most complex part of the Perl 5
1140 meta-object protocol. It controls the introspection and
1141 manipulation of Perl 5 classes (and it can create them too). The
1142 best way to understand what this module can do, is to read the
1143 documentation for each of it's methods.
1147 =head2 Self Introspection
1153 This will return a B<Class::MOP::Class> instance which is related
1154 to this class. Thereby allowing B<Class::MOP::Class> to actually
1157 As with B<Class::MOP::Attribute>, B<Class::MOP> will actually
1158 bootstrap this module by installing a number of attribute meta-objects
1159 into it's metaclass. This will allow this class to reap all the benifits
1160 of the MOP when subclassing it.
1164 =head2 Class construction
1166 These methods will handle creating B<Class::MOP::Class> objects,
1167 which can be used to both create new classes, and analyze
1168 pre-existing classes.
1170 This module will internally store references to all the instances
1171 you create with these methods, so that they do not need to be
1172 created any more than nessecary. Basically, they are singletons.
1176 =item B<create ($package_name,
1177 version =E<gt> ?$version,
1178 authority =E<gt> ?$authority,
1179 superclasses =E<gt> ?@superclasses,
1180 methods =E<gt> ?%methods,
1181 attributes =E<gt> ?%attributes)>
1183 This returns a B<Class::MOP::Class> object, bringing the specified
1184 C<$package_name> into existence and adding any of the C<$version>,
1185 C<$authority>, C<@superclasses>, C<%methods> and C<%attributes> to
1188 =item B<create_anon_class (superclasses =E<gt> ?@superclasses,
1189 methods =E<gt> ?%methods,
1190 attributes =E<gt> ?%attributes)>
1192 This will create an anonymous class, it works much like C<create> but
1193 it does not need a C<$package_name>. Instead it will create a suitably
1194 unique package name for you to stash things into.
1196 On very important distinction is that anon classes are destroyed once
1197 the metaclass they are attached to goes out of scope. In the DESTROY
1198 method, the created package will be removed from the symbol table.
1200 It is also worth noting that any instances created with an anon-class
1201 will keep a special reference to the anon-meta which will prevent the
1202 anon-class from going out of scope until all instances of it have also
1203 been destroyed. This however only works for HASH based instance types,
1204 as we use a special reserved slot (C<__MOP__>) to store this.
1206 =item B<initialize ($package_name, %options)>
1208 This initializes and returns returns a B<Class::MOP::Class> object
1209 for a given a C<$package_name>.
1211 =item B<construct_class_instance (%options)>
1213 This will construct an instance of B<Class::MOP::Class>, it is
1214 here so that we can actually "tie the knot" for B<Class::MOP::Class>
1215 to use C<construct_instance> once all the bootstrapping is done. This
1216 method is used internally by C<initialize> and should never be called
1217 from outside of that method really.
1219 =item B<check_metaclass_compatability>
1221 This method is called as the very last thing in the
1222 C<construct_class_instance> method. This will check that the
1223 metaclass you are creating is compatible with the metaclasses of all
1224 your ancestors. For more inforamtion about metaclass compatibility
1225 see the C<About Metaclass compatibility> section in L<Class::MOP>.
1227 =item B<update_package_cache_flag>
1229 This will reset the package cache flag for this particular metaclass
1230 it is basically the value of the C<Class::MOP::get_package_cache_flag>
1231 function. This is very rarely needed from outside of C<Class::MOP::Class>
1232 but in some cases you might want to use it, so it is here.
1234 =item B<reset_package_cache_flag>
1236 Clears the package cache flag to announce to the internals that we need
1237 to rebuild the method map.
1239 =item B<add_meta_instance_dependencies>
1241 Registers this class as dependent on its superclasses.
1243 Only superclasses from which this class inherits attributes will be added.
1245 =item B<remove_meta_instance_depdendencies>
1247 Unregisters this class from its superclasses.
1249 =item B<update_meta_instance_dependencies>
1251 Reregisters if necessary.
1253 =item B<add_dependent_meta_instance> $metaclass
1255 Registers the class as having a meta instance dependent on this class.
1257 =item B<remove_dependent_meta_instance> $metaclass
1259 Remove the class from the list of dependent classes.
1261 =item B<invalidate_meta_instances>
1263 Clears the cached meta instance for this metaclass and all of the registered
1264 classes with dependent meta instances.
1266 Called by C<add_attribute> and C<remove_attribute> to recalculate the attribute
1269 =item B<invalidate_meta_instance>
1271 Used by C<invalidate_meta_instances>.
1275 =head2 Object instance construction and cloning
1277 These methods are B<entirely optional>, it is up to you whether you want
1282 =item B<instance_metaclass>
1284 Returns the class name of the instance metaclass, see L<Class::MOP::Instance>
1285 for more information on the instance metaclasses.
1287 =item B<get_meta_instance>
1289 Returns an instance of L<Class::MOP::Instance> to be used in the construction
1290 of a new instance of the class.
1292 =item B<create_meta_instance>
1294 Called by C<get_meta_instance> if necessary.
1296 =item B<new_object (%params)>
1298 This is a convience method for creating a new object of the class, and
1299 blessing it into the appropriate package as well. Ideally your class
1300 would call a C<new> this method like so:
1303 my ($class, %param) = @_;
1304 $class->meta->new_object(%params);
1307 =item B<construct_instance (%params)>
1309 This method is used to construct an instance structure suitable for
1310 C<bless>-ing into your package of choice. It works in conjunction
1311 with the Attribute protocol to collect all applicable attributes.
1313 This will construct and instance using a HASH ref as storage
1314 (currently only HASH references are supported). This will collect all
1315 the applicable attributes and layout out the fields in the HASH ref,
1316 it will then initialize them using either use the corresponding key
1317 in C<%params> or any default value or initializer found in the
1318 attribute meta-object.
1320 =item B<clone_object ($instance, %params)>
1322 This is a convience method for cloning an object instance, then
1323 blessing it into the appropriate package. This method will call
1324 C<clone_instance>, which performs a shallow copy of the object,
1325 see that methods documentation for more details. Ideally your
1326 class would call a C<clone> this method like so:
1328 sub MyClass::clone {
1329 my ($self, %param) = @_;
1330 $self->meta->clone_object($self, %params);
1333 =item B<clone_instance($instance, %params)>
1335 This method is a compliment of C<construct_instance> (which means if
1336 you override C<construct_instance>, you need to override this one too),
1337 and clones the instance shallowly.
1339 The cloned structure returned is (like with C<construct_instance>) an
1340 unC<bless>ed HASH reference, it is your responsibility to then bless
1341 this cloned structure into the right class (which C<clone_object> will
1344 As of 0.11, this method will clone the C<$instance> structure shallowly,
1345 as opposed to the deep cloning implemented in prior versions. After much
1346 thought, research and discussion, I have decided that anything but basic
1347 shallow cloning is outside the scope of the meta-object protocol. I
1348 think Yuval "nothingmuch" Kogman put it best when he said that cloning
1349 is too I<context-specific> to be part of the MOP.
1351 =item B<rebless_instance($instance, ?%params)>
1353 This will change the class of C<$instance> to the class of the invoking
1354 C<Class::MOP::Class>. You may only rebless the instance to a subclass of
1355 itself. You may pass in optional C<%params> which are like constructor
1356 params and will override anything already defined in the instance.
1360 =head2 Informational
1362 These are a few predicate methods for asking information about the class.
1366 =item B<is_anon_class>
1368 This returns true if the class is a C<Class::MOP::Class> created anon class.
1372 This returns true if the class is still mutable.
1374 =item B<is_immutable>
1376 This returns true if the class has been made immutable.
1380 =head2 Inheritance Relationships
1384 =item B<superclasses (?@superclasses)>
1386 This is a read-write attribute which represents the superclass
1387 relationships of the class the B<Class::MOP::Class> instance is
1388 associated with. Basically, it can get and set the C<@ISA> for you.
1390 =item B<class_precedence_list>
1392 This computes the a list of all the class's ancestors in the same order
1393 in which method dispatch will be done. This is similair to what
1394 B<Class::ISA::super_path> does, but we don't remove duplicate names.
1396 =item B<linearized_isa>
1398 This returns a list based on C<class_precedence_list> but with all
1403 This returns a list of subclasses for this class.
1411 =item B<get_method_map>
1413 Returns a HASH ref of name to CODE reference mapping for this class.
1415 =item B<method_metaclass>
1417 Returns the class name of the method metaclass, see L<Class::MOP::Method>
1418 for more information on the method metaclasses.
1420 =item B<add_method ($method_name, $method)>
1422 This will take a C<$method_name> and CODE reference to that
1423 C<$method> and install it into the class's package.
1426 This does absolutely nothing special to C<$method>
1427 other than use B<Sub::Name> to make sure it is tagged with the
1428 correct name, and therefore show up correctly in stack traces and
1431 =item B<alias_method ($method_name, $method)>
1433 This will take a C<$method_name> and CODE reference to that
1434 C<$method> and alias the method into the class's package.
1437 Unlike C<add_method>, this will B<not> try to name the
1438 C<$method> using B<Sub::Name>, it only aliases the method in
1439 the class's package.
1441 =item B<has_method ($method_name)>
1443 This just provides a simple way to check if the class implements
1444 a specific C<$method_name>. It will I<not> however, attempt to check
1445 if the class inherits the method (use C<UNIVERSAL::can> for that).
1447 This will correctly handle functions defined outside of the package
1448 that use a fully qualified name (C<sub Package::name { ... }>).
1450 This will correctly handle functions renamed with B<Sub::Name> and
1451 installed using the symbol tables. However, if you are naming the
1452 subroutine outside of the package scope, you must use the fully
1453 qualified name, including the package name, for C<has_method> to
1454 correctly identify it.
1456 This will attempt to correctly ignore functions imported from other
1457 packages using B<Exporter>. It breaks down if the function imported
1458 is an C<__ANON__> sub (such as with C<use constant>), which very well
1459 may be a valid method being applied to the class.
1461 In short, this method cannot always be trusted to determine if the
1462 C<$method_name> is actually a method. However, it will DWIM about
1463 90% of the time, so it's a small trade off I think.
1465 =item B<get_method ($method_name)>
1467 This will return a Class::MOP::Method instance related to the specified
1468 C<$method_name>, or return undef if that method does not exist.
1470 The Class::MOP::Method is codifiable, so you can use it like a normal
1471 CODE reference, see L<Class::MOP::Method> for more information.
1473 =item B<find_method_by_name ($method_name)>
1475 This will return a CODE reference of the specified C<$method_name>,
1476 or return undef if that method does not exist.
1478 Unlike C<get_method> this will also look in the superclasses.
1480 =item B<remove_method ($method_name)>
1482 This will attempt to remove a given C<$method_name> from the class.
1483 It will return the CODE reference that it has removed, and will
1484 attempt to use B<Sub::Name> to clear the methods associated name.
1486 =item B<get_method_list>
1488 This will return a list of method names for all I<locally> defined
1489 methods. It does B<not> provide a list of all applicable methods,
1490 including any inherited ones. If you want a list of all applicable
1491 methods, use the C<compute_all_applicable_methods> method.
1493 =item B<get_all_methods>
1495 This will traverse the inheritance heirachy and return a list of all
1496 the applicable L<Class::MOP::Method> objects for this class.
1498 =item B<compute_all_applicable_methods>
1502 This method returns a list of hashes describing the all the methods of the
1505 Use L<get_all_methods>, which is easier/better/faster. This method predates
1506 L<Class::MOP::Method>.
1508 =item B<find_all_methods_by_name ($method_name)>
1510 This will traverse the inheritence hierarchy and locate all methods
1511 with a given C<$method_name>. Similar to
1512 C<compute_all_applicable_methods> it returns a list of HASH references
1513 with the following information; method name (which will always be the
1514 same as C<$method_name>), the name of the class in which the method
1515 lives and a CODE reference for the actual method.
1517 The list of methods produced is a distinct list, meaning there are no
1518 duplicates in it. This is especially useful for things like object
1519 initialization and destruction where you only want the method called
1520 once, and in the correct order.
1522 =item B<find_next_method_by_name ($method_name)>
1524 This will return the first method to match a given C<$method_name> in
1525 the superclasses, this is basically equivalent to calling
1526 C<SUPER::$method_name>, but it can be dispatched at runtime.
1530 =head2 Method Modifiers
1532 Method modifiers are a concept borrowed from CLOS, in which a method
1533 can be wrapped with I<before>, I<after> and I<around> method modifiers
1534 that will be called everytime the method is called.
1536 =head3 How method modifiers work?
1538 Method modifiers work by wrapping the original method and then replacing
1539 it in the classes symbol table. The wrappers will handle calling all the
1540 modifiers in the appropariate orders and preserving the calling context
1541 for the original method.
1543 Each method modifier serves a particular purpose, which may not be
1544 obvious to users of other method wrapping modules. To start with, the
1545 return values of I<before> and I<after> modifiers are ignored. This is
1546 because thier purpose is B<not> to filter the input and output of the
1547 primary method (this is done with an I<around> modifier). This may seem
1548 like an odd restriction to some, but doing this allows for simple code
1549 to be added at the begining or end of a method call without jeapordizing
1550 the normal functioning of the primary method or placing any extra
1551 responsibility on the code of the modifier. Of course if you have more
1552 complex needs, then use the I<around> modifier, which uses a variation
1553 of continutation passing style to allow for a high degree of flexibility.
1555 Before and around modifiers are called in last-defined-first-called order,
1556 while after modifiers are called in first-defined-first-called order. So
1557 the call tree might looks something like this:
1567 To see examples of using method modifiers, see the following examples
1568 included in the distribution; F<InstanceCountingClass>, F<Perl6Attribute>,
1569 F<AttributesWithHistory> and F<C3MethodDispatchOrder>. There is also a
1570 classic CLOS usage example in the test F<017_add_method_modifier.t>.
1572 =head3 What is the performance impact?
1574 Of course there is a performance cost associated with method modifiers,
1575 but we have made every effort to make that cost be directly proportional
1576 to the amount of modifier features you utilize.
1578 The wrapping method does it's best to B<only> do as much work as it
1579 absolutely needs to. In order to do this we have moved some of the
1580 performance costs to set-up time, where they are easier to amortize.
1582 All this said, my benchmarks have indicated the following:
1584 simple wrapper with no modifiers 100% slower
1585 simple wrapper with simple before modifier 400% slower
1586 simple wrapper with simple after modifier 450% slower
1587 simple wrapper with simple around modifier 500-550% slower
1588 simple wrapper with all 3 modifiers 1100% slower
1590 These numbers may seem daunting, but you must remember, every feature
1591 comes with some cost. To put things in perspective, just doing a simple
1592 C<AUTOLOAD> which does nothing but extract the name of the method called
1593 and return it costs about 400% over a normal method call.
1597 =item B<add_before_method_modifier ($method_name, $code)>
1599 This will wrap the method at C<$method_name> and the supplied C<$code>
1600 will be passed the C<@_> arguments, and called before the original
1601 method is called. As specified above, the return value of the I<before>
1602 method modifiers is ignored, and it's ability to modify C<@_> is
1603 fairly limited. If you need to do either of these things, use an
1604 C<around> method modifier.
1606 =item B<add_after_method_modifier ($method_name, $code)>
1608 This will wrap the method at C<$method_name> so that the original
1609 method will be called, it's return values stashed, and then the
1610 supplied C<$code> will be passed the C<@_> arguments, and called.
1611 As specified above, the return value of the I<after> method
1612 modifiers is ignored, and it cannot modify the return values of
1613 the original method. If you need to do either of these things, use an
1614 C<around> method modifier.
1616 =item B<add_around_method_modifier ($method_name, $code)>
1618 This will wrap the method at C<$method_name> so that C<$code>
1619 will be called and passed the original method as an extra argument
1620 at the begining of the C<@_> argument list. This is a variation of
1621 continuation passing style, where the function prepended to C<@_>
1622 can be considered a continuation. It is up to C<$code> if it calls
1623 the original method or not, there is no restriction on what the
1624 C<$code> can or cannot do.
1630 It should be noted that since there is no one consistent way to define
1631 the attributes of a class in Perl 5. These methods can only work with
1632 the information given, and can not easily discover information on
1633 their own. See L<Class::MOP::Attribute> for more details.
1637 =item B<attribute_metaclass>
1639 Returns the class name of the attribute metaclass, see L<Class::MOP::Attribute>
1640 for more information on the attribute metaclasses.
1642 =item B<get_attribute_map>
1644 This returns a HASH ref of name to attribute meta-object mapping.
1646 =item B<add_attribute ($attribute_meta_object | ($attribute_name, %attribute_spec))>
1648 This stores the C<$attribute_meta_object> (or creates one from the
1649 C<$attribute_name> and C<%attribute_spec>) in the B<Class::MOP::Class>
1650 instance associated with the given class. Unlike methods, attributes
1651 within the MOP are stored as meta-information only. They will be used
1652 later to construct instances from (see C<construct_instance> above).
1653 More details about the attribute meta-objects can be found in the
1654 L<Class::MOP::Attribute> or the L<Class::MOP/The Attribute protocol>
1657 It should be noted that any accessor, reader/writer or predicate
1658 methods which the C<$attribute_meta_object> has will be installed
1659 into the class at this time.
1662 If an attribute already exists for C<$attribute_name>, the old one
1663 will be removed (as well as removing all it's accessors), and then
1666 =item B<has_attribute ($attribute_name)>
1668 Checks to see if this class has an attribute by the name of
1669 C<$attribute_name> and returns a boolean.
1671 =item B<get_attribute ($attribute_name)>
1673 Returns the attribute meta-object associated with C<$attribute_name>,
1674 if none is found, it will return undef.
1676 =item B<remove_attribute ($attribute_name)>
1678 This will remove the attribute meta-object stored at
1679 C<$attribute_name>, then return the removed attribute meta-object.
1682 Removing an attribute will only affect future instances of
1683 the class, it will not make any attempt to remove the attribute from
1684 any existing instances of the class.
1686 It should be noted that any accessor, reader/writer or predicate
1687 methods which the attribute meta-object stored at C<$attribute_name>
1688 has will be removed from the class at this time. This B<will> make
1689 these attributes somewhat inaccessable in previously created
1690 instances. But if you are crazy enough to do this at runtime, then
1691 you are crazy enough to deal with something like this :).
1693 =item B<get_attribute_list>
1695 This returns a list of attribute names which are defined in the local
1696 class. If you want a list of all applicable attributes for a class,
1697 use the C<compute_all_applicable_attributes> method.
1699 =item B<compute_all_applicable_attributes>
1701 =item B<get_all_attributes>
1703 This will traverse the inheritance heirachy and return a list of all
1704 the applicable L<Class::MOP::Attribute> objects for this class.
1706 C<get_all_attributes> is an alias for consistency with C<get_all_methods>.
1708 =item B<find_attribute_by_name ($attr_name)>
1710 This method will traverse the inheritance heirachy and find the
1711 first attribute whose name matches C<$attr_name>, then return it.
1712 It will return undef if nothing is found.
1716 =head2 Class Immutability
1720 =item B<make_immutable (%options)>
1722 This method will invoke a tranforamtion upon the class which will
1723 make it immutable. Details of this transformation can be found in
1724 the L<Class::MOP::Immutable> documentation.
1726 =item B<make_mutable>
1728 This method will reverse tranforamtion upon the class which
1731 =item B<get_immutable_transformer>
1733 Return a transformer suitable for making this class immutable or, if this
1734 class is immutable, the transformer used to make it immutable.
1736 =item B<get_immutable_options>
1738 If the class is immutable, return the options used to make it immutable.
1740 =item B<create_immutable_transformer>
1742 Create a transformer suitable for making this class immutable
1748 Stevan Little E<lt>stevan@iinteractive.comE<gt>
1750 =head1 COPYRIGHT AND LICENSE
1752 Copyright 2006-2008 by Infinity Interactive, Inc.
1754 L<http://www.iinteractive.com>
1756 This library is free software; you can redistribute it and/or modify
1757 it under the same terms as Perl itself.