2 package Moose::Meta::Attribute;
7 use Scalar::Util 'blessed', 'weaken';
11 our $VERSION = '0.57';
12 our $AUTHORITY = 'cpan:STEVAN';
14 use Moose::Meta::Method::Accessor;
16 use Moose::Util::TypeConstraints ();
18 use base 'Class::MOP::Attribute';
20 # options which are not directly used
21 # but we store them for metadata purposes
22 __PACKAGE__->meta->add_attribute('isa' => (reader => '_isa_metadata'));
23 __PACKAGE__->meta->add_attribute('does' => (reader => '_does_metadata'));
24 __PACKAGE__->meta->add_attribute('is' => (reader => '_is_metadata'));
26 # these are actual options for the attrs
27 __PACKAGE__->meta->add_attribute('required' => (reader => 'is_required' ));
28 __PACKAGE__->meta->add_attribute('lazy' => (reader => 'is_lazy' ));
29 __PACKAGE__->meta->add_attribute('lazy_build' => (reader => 'is_lazy_build' ));
30 __PACKAGE__->meta->add_attribute('coerce' => (reader => 'should_coerce' ));
31 __PACKAGE__->meta->add_attribute('weak_ref' => (reader => 'is_weak_ref' ));
32 __PACKAGE__->meta->add_attribute('auto_deref' => (reader => 'should_auto_deref'));
33 __PACKAGE__->meta->add_attribute('type_constraint' => (
34 reader => 'type_constraint',
35 predicate => 'has_type_constraint',
37 __PACKAGE__->meta->add_attribute('trigger' => (
39 predicate => 'has_trigger',
41 __PACKAGE__->meta->add_attribute('handles' => (
43 predicate => 'has_handles',
45 __PACKAGE__->meta->add_attribute('documentation' => (
46 reader => 'documentation',
47 predicate => 'has_documentation',
49 __PACKAGE__->meta->add_attribute('traits' => (
50 reader => 'applied_traits',
51 predicate => 'has_applied_traits',
54 # we need to have a ->does method in here to
55 # more easily support traits, and the introspection
56 # of those traits. We extend the does check to look
57 # for metatrait aliases.
59 my ($self, $role_name) = @_;
61 Moose::Util::resolve_metatrait_alias(Attribute => $role_name)
63 return 0 if !defined($name); # failed to load class
64 return Moose::Object::does($self, $name);
68 my ($class, $name, %options) = @_;
69 $class->_process_options($name, \%options) unless $options{__hack_no_process_options}; # used from clone()... YECHKKK FIXME ICKY YUCK GROSS
70 return $class->SUPER::new($name, %options);
73 sub interpolate_class_and_new {
74 my ($class, $name, @args) = @_;
76 my ( $new_class, @traits ) = $class->interpolate_class(@args);
78 $new_class->new($name, @args, ( scalar(@traits) ? ( traits => \@traits ) : () ) );
81 sub interpolate_class {
82 my ($class, %options) = @_;
84 $class = ref($class) || $class;
86 if ( my $metaclass_name = delete $options{metaclass} ) {
87 my $new_class = Moose::Util::resolve_metaclass_alias( Attribute => $metaclass_name );
89 if ( $class ne $new_class ) {
90 if ( $new_class->can("interpolate_class") ) {
91 return $new_class->interpolate_class(%options);
100 if (my $traits = $options{traits}) {
101 if ( @traits = grep { not $class->does($_) } map {
102 Moose::Util::resolve_metatrait_alias( Attribute => $_ )
106 my $anon_class = Moose::Meta::Class->create_anon_class(
107 superclasses => [ $class ],
108 roles => [ @traits ],
112 $class = $anon_class->name;
116 return ( wantarray ? ( $class, @traits ) : $class );
121 my @legal_options_for_inheritance = qw(
122 default coerce required
123 documentation lazy handles
124 builder type_constraint
127 sub legal_options_for_inheritance { @legal_options_for_inheritance }
130 # This method *must* be able to handle
131 # Class::MOP::Attribute instances as
132 # well. Yes, I know that is wrong, but
133 # apparently we didn't realize it was
134 # doing that and now we have some code
135 # which is dependent on it. The real
136 # solution of course is to push this
137 # feature back up into Class::MOP::Attribute
138 # but I not right now, I am too lazy.
139 # However if you are reading this and
140 # looking for something to do,.. please
143 sub clone_and_inherit_options {
144 my ($self, %options) = @_;
151 # we may want to extends a Class::MOP::Attribute
152 # in which case we need to be able to use the
153 # core set of legal options that have always
154 # been here. But we allows Moose::Meta::Attribute
155 # instances to changes them.
157 my @legal_options = $self->can('legal_options_for_inheritance')
158 ? $self->legal_options_for_inheritance
159 : @legal_options_for_inheritance;
161 foreach my $legal_option (@legal_options) {
162 if (exists $options{$legal_option}) {
163 $actual_options{$legal_option} = $options{$legal_option};
164 delete $options{$legal_option};
170 if (blessed($options{isa}) && $options{isa}->isa('Moose::Meta::TypeConstraint')) {
171 $type_constraint = $options{isa};
174 $type_constraint = Moose::Util::TypeConstraints::find_or_create_isa_type_constraint($options{isa});
175 (defined $type_constraint)
176 || confess "Could not find the type constraint '" . $options{isa} . "'";
179 $actual_options{type_constraint} = $type_constraint;
180 delete $options{isa};
183 if ($options{does}) {
185 if (blessed($options{does}) && $options{does}->isa('Moose::Meta::TypeConstraint')) {
186 $type_constraint = $options{does};
189 $type_constraint = Moose::Util::TypeConstraints::find_or_create_does_type_constraint($options{does});
190 (defined $type_constraint)
191 || confess "Could not find the type constraint '" . $options{does} . "'";
194 $actual_options{type_constraint} = $type_constraint;
195 delete $options{does};
199 # this doesn't apply to Class::MOP::Attributes,
200 # so we can ignore it for them.
202 if ($self->can('interpolate_class')) {
203 ( $actual_options{metaclass}, my @traits ) = $self->interpolate_class(%options);
206 my @all_traits = grep { $seen{$_}++ } @{ $self->applied_traits || [] }, @traits;
207 $actual_options{traits} = \@all_traits if @all_traits;
209 delete @options{qw(metaclass traits)};
212 (scalar keys %options == 0)
213 || confess "Illegal inherited options => (" . (join ', ' => keys %options) . ")";
216 $self->clone(%actual_options);
220 my ( $self, %params ) = @_;
222 my $class = $params{metaclass} || ref $self;
224 if ( 0 and $class eq ref $self ) {
225 return $self->SUPER::clone(%params);
227 my ( @init, @non_init );
229 foreach my $attr ( grep { $_->has_value($self) } $self->meta->compute_all_applicable_attributes ) {
230 push @{ $attr->has_init_arg ? \@init : \@non_init }, $attr;
233 my %new_params = ( ( map { $_->init_arg => $_->get_value($self) } @init ), %params );
235 my $name = delete $new_params{name};
237 my $clone = $class->new($name, %new_params, __hack_no_process_options => 1 );
239 foreach my $attr ( @non_init ) {
240 $attr->set_value($clone, $attr->get_value($self));
248 sub _process_options {
249 my ($class, $name, $options) = @_;
251 if (exists $options->{is}) {
253 ### -------------------------
254 ## is => ro, writer => _foo # turns into (reader => foo, writer => _foo) as before
255 ## is => rw, writer => _foo # turns into (reader => foo, writer => _foo)
256 ## is => rw, accessor => _foo # turns into (accessor => _foo)
257 ## is => ro, accessor => _foo # error, accesor is rw
258 ### -------------------------
260 if ($options->{is} eq 'ro') {
261 confess "Cannot define an accessor name on a read-only attribute, accessors are read/write"
262 if exists $options->{accessor};
263 $options->{reader} ||= $name;
265 elsif ($options->{is} eq 'rw') {
266 if ($options->{writer}) {
267 $options->{reader} ||= $name;
270 $options->{accessor} ||= $name;
274 confess "I do not understand this option (is => " . $options->{is} . ") on attribute ($name)"
278 if (exists $options->{isa}) {
279 if (exists $options->{does}) {
280 if (eval { $options->{isa}->can('does') }) {
281 ($options->{isa}->does($options->{does}))
282 || confess "Cannot have an isa option and a does option if the isa does not do the does on attribute ($name)";
285 confess "Cannot have an isa option which cannot ->does() on attribute ($name)";
289 # allow for anon-subtypes here ...
290 if (blessed($options->{isa}) && $options->{isa}->isa('Moose::Meta::TypeConstraint')) {
291 $options->{type_constraint} = $options->{isa};
294 $options->{type_constraint} = Moose::Util::TypeConstraints::find_or_create_isa_type_constraint($options->{isa});
297 elsif (exists $options->{does}) {
298 # allow for anon-subtypes here ...
299 if (blessed($options->{does}) && $options->{does}->isa('Moose::Meta::TypeConstraint')) {
300 $options->{type_constraint} = $options->{does};
303 $options->{type_constraint} = Moose::Util::TypeConstraints::find_or_create_does_type_constraint($options->{does});
307 if (exists $options->{coerce} && $options->{coerce}) {
308 (exists $options->{type_constraint})
309 || confess "You cannot have coercion without specifying a type constraint on attribute ($name)";
310 confess "You cannot have a weak reference to a coerced value on attribute ($name)"
311 if $options->{weak_ref};
314 if (exists $options->{trigger}) {
315 ('CODE' eq ref $options->{trigger})
316 || confess "Trigger must be a CODE ref on attribute ($name)";
319 if (exists $options->{auto_deref} && $options->{auto_deref}) {
320 (exists $options->{type_constraint})
321 || confess "You cannot auto-dereference without specifying a type constraint on attribute ($name)";
322 ($options->{type_constraint}->is_a_type_of('ArrayRef') ||
323 $options->{type_constraint}->is_a_type_of('HashRef'))
324 || confess "You cannot auto-dereference anything other than a ArrayRef or HashRef on attribute ($name)";
327 if (exists $options->{lazy_build} && $options->{lazy_build} == 1) {
328 confess("You can not use lazy_build and default for the same attribute ($name)")
329 if exists $options->{default};
330 $options->{lazy} = 1;
331 $options->{required} = 1;
332 $options->{builder} ||= "_build_${name}";
334 $options->{clearer} ||= "_clear${name}";
335 $options->{predicate} ||= "_has${name}";
338 $options->{clearer} ||= "clear_${name}";
339 $options->{predicate} ||= "has_${name}";
343 if (exists $options->{lazy} && $options->{lazy}) {
344 (exists $options->{default} || defined $options->{builder} )
345 || confess "You cannot have lazy attribute ($name) without specifying a default value for it";
348 if ( $options->{required} && !( ( !exists $options->{init_arg} || defined $options->{init_arg} ) || exists $options->{default} || defined $options->{builder} ) ) {
349 confess "You cannot have a required attribute ($name) without a default, builder, or an init_arg";
354 sub initialize_instance_slot {
355 my ($self, $meta_instance, $instance, $params) = @_;
356 my $init_arg = $self->init_arg();
357 # try to fetch the init arg from the %params ...
361 if ( defined($init_arg) and exists $params->{$init_arg}) {
362 $val = $params->{$init_arg};
366 # skip it if it's lazy
367 return if $self->is_lazy;
368 # and die if it's required and doesn't have a default value
369 confess "Attribute (" . $self->name . ") is required"
370 if $self->is_required && !$self->has_default && !$self->has_builder;
372 # if nothing was in the %params, we can use the
373 # attribute's default value (if it has one)
374 if ($self->has_default) {
375 $val = $self->default($instance);
378 elsif ($self->has_builder) {
379 $val = $self->_call_builder($instance);
384 return unless $value_is_set;
386 if ($self->has_type_constraint) {
387 my $type_constraint = $self->type_constraint;
388 if ($self->should_coerce && $type_constraint->has_coercion) {
389 $val = $type_constraint->coerce($val);
391 $type_constraint->check($val)
392 || confess "Attribute ("
394 . ") does not pass the type constraint because: "
395 . $type_constraint->get_message($val);
398 $self->set_initial_value($instance, $val);
399 $meta_instance->weaken_slot_value($instance, $self->name)
400 if ref $val && $self->is_weak_ref;
404 my ( $self, $instance ) = @_;
406 my $builder = $self->builder();
408 return $instance->$builder()
409 if $instance->can( $self->builder );
411 confess( blessed($instance)
412 . " does not support builder method '"
414 . "' for attribute '"
422 # this duplicates too much code from
423 # Class::MOP::Attribute, we need to
424 # refactor these bits eventually.
426 sub _set_initial_slot_value {
427 my ($self, $meta_instance, $instance, $value) = @_;
429 my $slot_name = $self->name;
431 return $meta_instance->set_slot_value($instance, $slot_name, $value)
432 unless $self->has_initializer;
434 my ($type_constraint, $can_coerce);
435 if ($self->has_type_constraint) {
436 $type_constraint = $self->type_constraint;
437 $can_coerce = ($self->should_coerce && $type_constraint->has_coercion);
442 if ($type_constraint) {
443 $val = $type_constraint->coerce($val)
445 $type_constraint->check($val)
446 || confess "Attribute ("
448 . ") does not pass the type constraint because: "
449 . $type_constraint->get_message($val);
451 $meta_instance->set_slot_value($instance, $slot_name, $val);
454 my $initializer = $self->initializer;
456 # most things will just want to set a value, so make it first arg
457 $instance->$initializer($value, $callback, $self);
461 my ($self, $instance, @args) = @_;
462 my $value = $args[0];
464 my $attr_name = $self->name;
466 if ($self->is_required and not @args) {
467 confess "Attribute ($attr_name) is required";
470 if ($self->has_type_constraint) {
472 my $type_constraint = $self->type_constraint;
474 if ($self->should_coerce) {
475 $value = $type_constraint->coerce($value);
477 $type_constraint->_compiled_type_constraint->($value)
478 || confess "Attribute ("
480 . ") does not pass the type constraint because "
481 . $type_constraint->get_message($value);
484 my $meta_instance = Class::MOP::Class->initialize(blessed($instance))
487 $meta_instance->set_slot_value($instance, $attr_name, $value);
489 if (ref $value && $self->is_weak_ref) {
490 $meta_instance->weaken_slot_value($instance, $attr_name);
493 if ($self->has_trigger) {
494 $self->trigger->($instance, $value, $self);
499 my ($self, $instance) = @_;
501 if ($self->is_lazy) {
502 unless ($self->has_value($instance)) {
504 if ($self->has_default) {
505 $value = $self->default($instance);
506 } elsif ( $self->has_builder ) {
507 $value = $self->_call_builder($instance);
509 if ($self->has_type_constraint) {
510 my $type_constraint = $self->type_constraint;
511 $value = $type_constraint->coerce($value)
512 if ($self->should_coerce);
513 $type_constraint->check($value)
514 || confess "Attribute (" . $self->name
515 . ") does not pass the type constraint because: "
516 . $type_constraint->get_message($value);
518 $self->set_initial_value($instance, $value);
522 if ($self->should_auto_deref) {
524 my $type_constraint = $self->type_constraint;
526 if ($type_constraint->is_a_type_of('ArrayRef')) {
527 my $rv = $self->SUPER::get_value($instance);
528 return unless defined $rv;
529 return wantarray ? @{ $rv } : $rv;
531 elsif ($type_constraint->is_a_type_of('HashRef')) {
532 my $rv = $self->SUPER::get_value($instance);
533 return unless defined $rv;
534 return wantarray ? %{ $rv } : $rv;
537 confess "Can not auto de-reference the type constraint '" . $type_constraint->name . "'";
543 return $self->SUPER::get_value($instance);
547 ## installing accessors
549 sub accessor_metaclass { 'Moose::Meta::Method::Accessor' }
551 sub install_accessors {
553 $self->SUPER::install_accessors(@_);
554 $self->install_delegation if $self->has_handles;
558 sub install_delegation {
562 # Here we canonicalize the 'handles' option
563 # this will sort out any details and always
564 # return an hash of methods which we want
565 # to delagate to, see that method for details
566 my %handles = $self->_canonicalize_handles;
568 # find the accessor method for this attribute
569 my $accessor = $self->_get_delegate_accessor;
571 # install the delegation ...
572 my $associated_class = $self->associated_class;
573 foreach my $handle (keys %handles) {
574 my $method_to_call = $handles{$handle};
575 my $class_name = $associated_class->name;
576 my $name = "${class_name}::${handle}";
578 (!$associated_class->has_method($handle))
579 || confess "You cannot overwrite a locally defined method ($handle) with a delegation";
582 # handles is not allowed to delegate
583 # any of these methods, as they will
584 # override the ones in your class, which
585 # is almost certainly not what you want.
587 # FIXME warn when $handle was explicitly specified, but not if the source is a regex or something
588 #cluck("Not delegating method '$handle' because it is a core method") and
589 next if $class_name->isa("Moose::Object") and $handle =~ /^BUILD|DEMOLISH$/ || Moose::Object->can($handle);
591 if ('CODE' eq ref($method_to_call)) {
592 $associated_class->add_method($handle => Class::MOP::subname($name, $method_to_call));
596 # we used to do a goto here, but the
597 # goto didn't handle failure correctly
598 # (it just returned nothing), so I took
599 # that out. However, the more I thought
600 # about it, the less I liked it doing
601 # the goto, and I prefered the act of
602 # delegation being actually represented
603 # in the stack trace.
605 $associated_class->add_method($handle => Class::MOP::subname($name, sub {
606 my $proxy = (shift)->$accessor();
608 || confess "Cannot delegate $handle to $method_to_call because " .
609 "the value of " . $self->name . " is not defined";
610 $proxy->$method_to_call(@_);
616 # private methods to help delegation ...
618 sub _get_delegate_accessor {
620 # find the accessor method for this attribute
621 my $accessor = $self->get_read_method_ref;
622 # then unpack it if we need too ...
623 $accessor = $accessor->body if blessed $accessor;
624 # return the accessor
628 sub _canonicalize_handles {
630 my $handles = $self->handles;
631 if (my $handle_type = ref($handles)) {
632 if ($handle_type eq 'HASH') {
635 elsif ($handle_type eq 'ARRAY') {
636 return map { $_ => $_ } @{$handles};
638 elsif ($handle_type eq 'Regexp') {
639 ($self->has_type_constraint)
640 || confess "Cannot delegate methods based on a RegExpr without a type constraint (isa)";
641 return map { ($_ => $_) }
642 grep { /$handles/ } $self->_get_delegate_method_list;
644 elsif ($handle_type eq 'CODE') {
645 return $handles->($self, $self->_find_delegate_metaclass);
648 confess "Unable to canonicalize the 'handles' option with $handles";
652 my $role_meta = eval { $handles->meta };
654 confess "Unable to canonicalize the 'handles' option with $handles because : $@";
657 (blessed $role_meta && $role_meta->isa('Moose::Meta::Role'))
658 || confess "Unable to canonicalize the 'handles' option with $handles because ->meta is not a Moose::Meta::Role";
660 return map { $_ => $_ } (
661 $role_meta->get_method_list,
662 $role_meta->get_required_method_list
667 sub _find_delegate_metaclass {
669 if (my $class = $self->_isa_metadata) {
670 # if the class does have
671 # a meta method, use it
672 return $class->meta if $class->can('meta');
673 # otherwise we might be
674 # dealing with a non-Moose
675 # class, and need to make
677 return Moose::Meta::Class->initialize($class);
679 elsif (my $role = $self->_does_metadata) {
680 # our role will always have
685 confess "Cannot find delegate metaclass for attribute " . $self->name;
689 sub _get_delegate_method_list {
691 my $meta = $self->_find_delegate_metaclass;
692 if ($meta->isa('Class::MOP::Class')) {
693 return map { $_->name } # NOTE: !never! delegate &meta
694 grep { $_->package_name ne 'Moose::Object' && $_->name ne 'meta' }
695 $meta->get_all_methods;
697 elsif ($meta->isa('Moose::Meta::Role')) {
698 return $meta->get_method_list;
701 confess "Unable to recognize the delegate metaclass '$meta'";
705 package Moose::Meta::Attribute::Custom::Moose;
706 sub register_implementation { 'Moose::Meta::Attribute' }
716 Moose::Meta::Attribute - The Moose attribute metaclass
720 This is a subclass of L<Class::MOP::Attribute> with Moose specific
723 For the most part, the only time you will ever encounter an
724 instance of this class is if you are doing some serious deep
725 introspection. To really understand this class, you need to refer
726 to the L<Class::MOP::Attribute> documentation.
730 =head2 Overridden methods
732 These methods override methods in L<Class::MOP::Attribute> and add
733 Moose specific features. You can safely assume though that they
734 will behave just as L<Class::MOP::Attribute> does.
744 =item B<initialize_instance_slot>
746 =item B<install_accessors>
748 =item B<install_delegation>
750 =item B<accessor_metaclass>
756 eval { $point->meta->get_attribute('x')->set_value($point, 'fourty-two') };
761 I<Attribute (x) does not pass the type constraint (Int) with 'fourty-two'>
763 Before setting the value, a check is made on the type constraint of
764 the attribute, if it has one, to see if the value passes it. If the
765 value fails to pass, the set operation dies with a L<Carp/confess>.
767 Any coercion to convert values is done before checking the type constraint.
769 To check a value against a type constraint before setting it, fetch the
770 attribute instance using L<Class::MOP::Class/find_attribute_by_name>,
771 fetch the type_constraint from the attribute using L<Moose::Meta::Attribute/type_constraint>
772 and call L<Moose::Meta::TypeConstraint/check>. See L<Moose::Cookbook::Basics::Recipe4>
777 =head2 Additional Moose features
779 Moose attributes support type-constraint checking, weak reference
780 creation and type coercion.
784 =item B<interpolate_class_and_new>
786 =item B<interpolate_class>
788 When called as a class method causes interpretation of the C<metaclass> and
791 =item B<clone_and_inherit_options>
793 This is to support the C<has '+foo'> feature, it clones an attribute
794 from a superclass and allows a very specific set of changes to be made
797 =item B<legal_options_for_inheritance>
799 Whitelist with options you can change. You can overload it in your custom
800 metaclass to allow your options be inheritable.
802 =item B<has_type_constraint>
804 Returns true if this meta-attribute has a type constraint.
806 =item B<type_constraint>
808 A read-only accessor for this meta-attribute's type constraint. For
809 more information on what you can do with this, see the documentation
810 for L<Moose::Meta::TypeConstraint>.
814 Returns true if this meta-attribute performs delegation.
818 This returns the value which was passed into the handles option.
822 Returns true if this meta-attribute produces a weak reference.
826 Returns true if this meta-attribute is required to have a value.
830 Returns true if this meta-attribute should be initialized lazily.
832 NOTE: lazy attributes, B<must> have a C<default> or C<builder> field set.
834 =item B<is_lazy_build>
836 Returns true if this meta-attribute should be initialized lazily through
837 the builder generated by lazy_build. Using C<lazy_build =E<gt> 1> will
838 make your attribute required and lazy. In addition it will set the builder, clearer
839 and predicate options for you using the following convention.
841 #If your attribute name starts with an underscore:
842 has '_foo' => (lazy_build => 1);
844 has '_foo' => (lazy => 1, required => 1, predicate => '_has_foo', clearer => '_clear_foo', builder => '_build__foo');
846 has '_foo' => (lazy => 1, required => 1, predicate => '_has_foo', clearer => '_clear_foo', default => sub{shift->_build__foo});
848 #If your attribute name does not start with an underscore:
849 has 'foo' => (lazy_build => 1);
851 has 'foo' => (lazy => 1, required => 1, predicate => 'has_foo', clearer => 'clear_foo', builder => '_build_foo');
853 has 'foo' => (lazy => 1, required => 1, predicate => 'has_foo', clearer => 'clear_foo', default => sub{shift->_build_foo});
855 The reason for the different naming of the C<builder> is that the C<builder>
856 method is a private method while the C<clearer> and C<predicate> methods
859 NOTE: This means your class should provide a method whose name matches the value
860 of the builder part, in this case _build__foo or _build_foo.
862 =item B<should_coerce>
864 Returns true if this meta-attribute should perform type coercion.
866 =item B<should_auto_deref>
868 Returns true if this meta-attribute should perform automatic
871 NOTE: This can only be done for attributes whose type constraint is
872 either I<ArrayRef> or I<HashRef>.
876 Returns true if this meta-attribute has a trigger set.
880 This is a CODE reference which will be executed every time the
881 value of an attribute is assigned. The CODE ref will get two values,
882 the invocant and the new value. This can be used to handle I<basic>
883 bi-directional relations.
885 =item B<documentation>
887 This is a string which contains the documentation for this attribute.
888 It serves no direct purpose right now, but it might in the future
889 in some kind of automated documentation system perhaps.
891 =item B<has_documentation>
893 Returns true if this meta-attribute has any documentation.
895 =item B<applied_traits>
897 This will return the ARRAY ref of all the traits applied to this
898 attribute, or if no traits have been applied, it returns C<undef>.
900 =item B<has_applied_traits>
902 Returns true if this meta-attribute has any traits applied.
908 All complex software has bugs lurking in it, and this module is no
909 exception. If you find a bug please either email me, or add the bug
914 Stevan Little E<lt>stevan@iinteractive.comE<gt>
916 Yuval Kogman E<lt>nothingmuch@woobling.comE<gt>
918 =head1 COPYRIGHT AND LICENSE
920 Copyright 2006-2008 by Infinity Interactive, Inc.
922 L<http://www.iinteractive.com>
924 This library is free software; you can redistribute it and/or modify
925 it under the same terms as Perl itself.