2 package Moose::Meta::Attribute;
7 use Scalar::Util 'blessed', 'weaken';
10 our $VERSION = '0.81';
11 our $AUTHORITY = 'cpan:STEVAN';
13 use Moose::Meta::Method::Accessor;
14 use Moose::Meta::Method::Delegation;
16 use Moose::Util::TypeConstraints ();
18 use base 'Class::MOP::Attribute';
20 # options which are not directly used
21 # but we store them for metadata purposes
22 __PACKAGE__->meta->add_attribute('isa' => (reader => '_isa_metadata'));
23 __PACKAGE__->meta->add_attribute('does' => (reader => '_does_metadata'));
24 __PACKAGE__->meta->add_attribute('is' => (reader => '_is_metadata'));
26 # these are actual options for the attrs
27 __PACKAGE__->meta->add_attribute('required' => (reader => 'is_required' ));
28 __PACKAGE__->meta->add_attribute('lazy' => (reader => 'is_lazy' ));
29 __PACKAGE__->meta->add_attribute('lazy_build' => (reader => 'is_lazy_build' ));
30 __PACKAGE__->meta->add_attribute('coerce' => (reader => 'should_coerce' ));
31 __PACKAGE__->meta->add_attribute('weak_ref' => (reader => 'is_weak_ref' ));
32 __PACKAGE__->meta->add_attribute('auto_deref' => (reader => 'should_auto_deref'));
33 __PACKAGE__->meta->add_attribute('type_constraint' => (
34 reader => 'type_constraint',
35 predicate => 'has_type_constraint',
37 __PACKAGE__->meta->add_attribute('trigger' => (
39 predicate => 'has_trigger',
41 __PACKAGE__->meta->add_attribute('handles' => (
43 predicate => 'has_handles',
45 __PACKAGE__->meta->add_attribute('documentation' => (
46 reader => 'documentation',
47 predicate => 'has_documentation',
49 __PACKAGE__->meta->add_attribute('traits' => (
50 reader => 'applied_traits',
51 predicate => 'has_applied_traits',
54 # we need to have a ->does method in here to
55 # more easily support traits, and the introspection
56 # of those traits. We extend the does check to look
57 # for metatrait aliases.
59 my ($self, $role_name) = @_;
61 Moose::Util::resolve_metatrait_alias(Attribute => $role_name)
63 return 0 if !defined($name); # failed to load class
64 return $self->Moose::Object::does($name);
69 my $class = ( ref $self && $self->associated_class ) || "Moose::Meta::Class";
70 unshift @_, "message" if @_ % 2 == 1;
71 unshift @_, attr => $self if ref $self;
73 my $handler = $class->can("throw_error"); # to avoid incrementing depth by 1
78 my ($class, $name, %options) = @_;
79 $class->_process_options($name, \%options) unless $options{__hack_no_process_options}; # used from clone()... YECHKKK FIXME ICKY YUCK GROSS
80 return $class->SUPER::new($name, %options);
83 sub interpolate_class_and_new {
84 my ($class, $name, @args) = @_;
86 my ( $new_class, @traits ) = $class->interpolate_class(@args);
88 $new_class->new($name, @args, ( scalar(@traits) ? ( traits => \@traits ) : () ) );
91 sub interpolate_class {
92 my ($class, %options) = @_;
94 $class = ref($class) || $class;
96 if ( my $metaclass_name = delete $options{metaclass} ) {
97 my $new_class = Moose::Util::resolve_metaclass_alias( Attribute => $metaclass_name );
99 if ( $class ne $new_class ) {
100 if ( $new_class->can("interpolate_class") ) {
101 return $new_class->interpolate_class(%options);
110 if (my $traits = $options{traits}) {
112 while ($i < @$traits) {
113 my $trait = $traits->[$i++];
114 next if ref($trait); # options to a trait we discarded
116 $trait = Moose::Util::resolve_metatrait_alias(Attribute => $trait)
119 next if $class->does($trait);
121 push @traits, $trait;
124 push @traits, $traits->[$i++]
125 if $traits->[$i] && ref($traits->[$i]);
129 my $anon_class = Moose::Meta::Class->create_anon_class(
130 superclasses => [ $class ],
131 roles => [ @traits ],
135 $class = $anon_class->name;
139 return ( wantarray ? ( $class, @traits ) : $class );
144 my @legal_options_for_inheritance = qw(
145 default coerce required
146 documentation lazy handles
147 builder type_constraint
152 sub legal_options_for_inheritance { @legal_options_for_inheritance }
155 # This method *must* be able to handle
156 # Class::MOP::Attribute instances as
157 # well. Yes, I know that is wrong, but
158 # apparently we didn't realize it was
159 # doing that and now we have some code
160 # which is dependent on it. The real
161 # solution of course is to push this
162 # feature back up into Class::MOP::Attribute
163 # but I not right now, I am too lazy.
164 # However if you are reading this and
165 # looking for something to do,.. please
168 sub clone_and_inherit_options {
169 my ($self, %options) = @_;
176 # we may want to extends a Class::MOP::Attribute
177 # in which case we need to be able to use the
178 # core set of legal options that have always
179 # been here. But we allows Moose::Meta::Attribute
180 # instances to changes them.
182 my @legal_options = $self->can('legal_options_for_inheritance')
183 ? $self->legal_options_for_inheritance
184 : @legal_options_for_inheritance;
186 foreach my $legal_option (@legal_options) {
187 if (exists $options{$legal_option}) {
188 $actual_options{$legal_option} = $options{$legal_option};
189 delete $options{$legal_option};
195 if (blessed($options{isa}) && $options{isa}->isa('Moose::Meta::TypeConstraint')) {
196 $type_constraint = $options{isa};
199 $type_constraint = Moose::Util::TypeConstraints::find_or_create_isa_type_constraint($options{isa});
200 (defined $type_constraint)
201 || $self->throw_error("Could not find the type constraint '" . $options{isa} . "'", data => $options{isa});
204 $actual_options{type_constraint} = $type_constraint;
205 delete $options{isa};
208 if ($options{does}) {
210 if (blessed($options{does}) && $options{does}->isa('Moose::Meta::TypeConstraint')) {
211 $type_constraint = $options{does};
214 $type_constraint = Moose::Util::TypeConstraints::find_or_create_does_type_constraint($options{does});
215 (defined $type_constraint)
216 || $self->throw_error("Could not find the type constraint '" . $options{does} . "'", data => $options{does});
219 $actual_options{type_constraint} = $type_constraint;
220 delete $options{does};
224 # this doesn't apply to Class::MOP::Attributes,
225 # so we can ignore it for them.
227 if ($self->can('interpolate_class')) {
228 ( $actual_options{metaclass}, my @traits ) = $self->interpolate_class(%options);
231 my @all_traits = grep { $seen{$_}++ } @{ $self->applied_traits || [] }, @traits;
232 $actual_options{traits} = \@all_traits if @all_traits;
234 delete @options{qw(metaclass traits)};
237 (scalar keys %options == 0)
238 || $self->throw_error("Illegal inherited options => (" . (join ', ' => keys %options) . ")", data => \%options);
241 $self->clone(%actual_options);
245 my ( $self, %params ) = @_;
247 my $class = $params{metaclass} || ref $self;
249 my ( @init, @non_init );
251 foreach my $attr ( grep { $_->has_value($self) } Class::MOP::class_of($self)->get_all_attributes ) {
252 push @{ $attr->has_init_arg ? \@init : \@non_init }, $attr;
255 my %new_params = ( ( map { $_->init_arg => $_->get_value($self) } @init ), %params );
257 my $name = delete $new_params{name};
259 my $clone = $class->new($name, %new_params, __hack_no_process_options => 1 );
261 foreach my $attr ( @non_init ) {
262 $attr->set_value($clone, $attr->get_value($self));
268 sub _process_options {
269 my ($class, $name, $options) = @_;
271 if (exists $options->{is}) {
273 ### -------------------------
274 ## is => ro, writer => _foo # turns into (reader => foo, writer => _foo) as before
275 ## is => rw, writer => _foo # turns into (reader => foo, writer => _foo)
276 ## is => rw, accessor => _foo # turns into (accessor => _foo)
277 ## is => ro, accessor => _foo # error, accesor is rw
278 ### -------------------------
280 if ($options->{is} eq 'ro') {
281 $class->throw_error("Cannot define an accessor name on a read-only attribute, accessors are read/write", data => $options)
282 if exists $options->{accessor};
283 $options->{reader} ||= $name;
285 elsif ($options->{is} eq 'rw') {
286 if ($options->{writer}) {
287 $options->{reader} ||= $name;
290 $options->{accessor} ||= $name;
294 $class->throw_error("I do not understand this option (is => " . $options->{is} . ") on attribute ($name)", data => $options->{is});
298 if (exists $options->{isa}) {
299 if (exists $options->{does}) {
300 if (eval { $options->{isa}->can('does') }) {
301 ($options->{isa}->does($options->{does}))
302 || $class->throw_error("Cannot have an isa option and a does option if the isa does not do the does on attribute ($name)", data => $options);
305 $class->throw_error("Cannot have an isa option which cannot ->does() on attribute ($name)", data => $options);
309 # allow for anon-subtypes here ...
310 if (blessed($options->{isa}) && $options->{isa}->isa('Moose::Meta::TypeConstraint')) {
311 $options->{type_constraint} = $options->{isa};
314 $options->{type_constraint} = Moose::Util::TypeConstraints::find_or_create_isa_type_constraint($options->{isa});
317 elsif (exists $options->{does}) {
318 # allow for anon-subtypes here ...
319 if (blessed($options->{does}) && $options->{does}->isa('Moose::Meta::TypeConstraint')) {
320 $options->{type_constraint} = $options->{does};
323 $options->{type_constraint} = Moose::Util::TypeConstraints::find_or_create_does_type_constraint($options->{does});
327 if (exists $options->{coerce} && $options->{coerce}) {
328 (exists $options->{type_constraint})
329 || $class->throw_error("You cannot have coercion without specifying a type constraint on attribute ($name)", data => $options);
330 $class->throw_error("You cannot have a weak reference to a coerced value on attribute ($name)", data => $options)
331 if $options->{weak_ref};
334 if (exists $options->{trigger}) {
335 ('CODE' eq ref $options->{trigger})
336 || $class->throw_error("Trigger must be a CODE ref on attribute ($name)", data => $options->{trigger});
339 if (exists $options->{auto_deref} && $options->{auto_deref}) {
340 (exists $options->{type_constraint})
341 || $class->throw_error("You cannot auto-dereference without specifying a type constraint on attribute ($name)", data => $options);
342 ($options->{type_constraint}->is_a_type_of('ArrayRef') ||
343 $options->{type_constraint}->is_a_type_of('HashRef'))
344 || $class->throw_error("You cannot auto-dereference anything other than a ArrayRef or HashRef on attribute ($name)", data => $options);
347 if (exists $options->{lazy_build} && $options->{lazy_build} == 1) {
348 $class->throw_error("You can not use lazy_build and default for the same attribute ($name)", data => $options)
349 if exists $options->{default};
350 $options->{lazy} = 1;
351 $options->{builder} ||= "_build_${name}";
353 $options->{clearer} ||= "_clear${name}";
354 $options->{predicate} ||= "_has${name}";
357 $options->{clearer} ||= "clear_${name}";
358 $options->{predicate} ||= "has_${name}";
362 if (exists $options->{lazy} && $options->{lazy}) {
363 (exists $options->{default} || defined $options->{builder} )
364 || $class->throw_error("You cannot have lazy attribute ($name) without specifying a default value for it", data => $options);
367 if ( $options->{required} && !( ( !exists $options->{init_arg} || defined $options->{init_arg} ) || exists $options->{default} || defined $options->{builder} ) ) {
368 $class->throw_error("You cannot have a required attribute ($name) without a default, builder, or an init_arg", data => $options);
373 sub initialize_instance_slot {
374 my ($self, $meta_instance, $instance, $params) = @_;
375 my $init_arg = $self->init_arg();
376 # try to fetch the init arg from the %params ...
380 if ( defined($init_arg) and exists $params->{$init_arg}) {
381 $val = $params->{$init_arg};
385 # skip it if it's lazy
386 return if $self->is_lazy;
387 # and die if it's required and doesn't have a default value
388 $self->throw_error("Attribute (" . $self->name . ") is required", object => $instance, data => $params)
389 if $self->is_required && !$self->has_default && !$self->has_builder;
391 # if nothing was in the %params, we can use the
392 # attribute's default value (if it has one)
393 if ($self->has_default) {
394 $val = $self->default($instance);
397 elsif ($self->has_builder) {
398 $val = $self->_call_builder($instance);
403 return unless $value_is_set;
405 $val = $self->_coerce_and_verify( $val, $instance );
407 $self->set_initial_value($instance, $val);
408 $meta_instance->weaken_slot_value($instance, $self->name)
409 if ref $val && $self->is_weak_ref;
413 my ( $self, $instance ) = @_;
415 my $builder = $self->builder();
417 return $instance->$builder()
418 if $instance->can( $self->builder );
420 $self->throw_error( blessed($instance)
421 . " does not support builder method '"
423 . "' for attribute '"
433 # this duplicates too much code from
434 # Class::MOP::Attribute, we need to
435 # refactor these bits eventually.
437 sub _set_initial_slot_value {
438 my ($self, $meta_instance, $instance, $value) = @_;
440 my $slot_name = $self->name;
442 return $meta_instance->set_slot_value($instance, $slot_name, $value)
443 unless $self->has_initializer;
445 my ($type_constraint, $can_coerce);
446 if ($self->has_type_constraint) {
447 $type_constraint = $self->type_constraint;
448 $can_coerce = ($self->should_coerce && $type_constraint->has_coercion);
452 my $val = $self->_coerce_and_verify( shift, $instance );;
454 $meta_instance->set_slot_value($instance, $slot_name, $val);
457 my $initializer = $self->initializer;
459 # most things will just want to set a value, so make it first arg
460 $instance->$initializer($value, $callback, $self);
464 my ($self, $instance, @args) = @_;
465 my $value = $args[0];
467 my $attr_name = $self->name;
469 if ($self->is_required and not @args) {
470 $self->throw_error("Attribute ($attr_name) is required", object => $instance);
473 $value = $self->_coerce_and_verify( $value, $instance );
475 my $meta_instance = Class::MOP::Class->initialize(blessed($instance))
478 $meta_instance->set_slot_value($instance, $attr_name, $value);
480 if (ref $value && $self->is_weak_ref) {
481 $meta_instance->weaken_slot_value($instance, $attr_name);
484 if ($self->has_trigger) {
485 $self->trigger->($instance, $value);
490 my ($self, $instance) = @_;
492 if ($self->is_lazy) {
493 unless ($self->has_value($instance)) {
495 if ($self->has_default) {
496 $value = $self->default($instance);
497 } elsif ( $self->has_builder ) {
498 $value = $self->_call_builder($instance);
501 $value = $self->_coerce_and_verify( $value, $instance );
503 $self->set_initial_value($instance, $value);
507 if ($self->should_auto_deref) {
509 my $type_constraint = $self->type_constraint;
511 if ($type_constraint->is_a_type_of('ArrayRef')) {
512 my $rv = $self->SUPER::get_value($instance);
513 return unless defined $rv;
514 return wantarray ? @{ $rv } : $rv;
516 elsif ($type_constraint->is_a_type_of('HashRef')) {
517 my $rv = $self->SUPER::get_value($instance);
518 return unless defined $rv;
519 return wantarray ? %{ $rv } : $rv;
522 $self->throw_error("Can not auto de-reference the type constraint '" . $type_constraint->name . "'", object => $instance, type_constraint => $type_constraint);
528 return $self->SUPER::get_value($instance);
532 ## installing accessors
534 sub accessor_metaclass { 'Moose::Meta::Method::Accessor' }
536 sub install_accessors {
538 $self->SUPER::install_accessors(@_);
539 $self->install_delegation if $self->has_handles;
543 sub remove_accessors {
545 $self->SUPER::remove_accessors(@_);
546 $self->remove_delegation if $self->has_handles;
550 sub install_delegation {
554 # Here we canonicalize the 'handles' option
555 # this will sort out any details and always
556 # return an hash of methods which we want
557 # to delagate to, see that method for details
558 my %handles = $self->_canonicalize_handles;
561 # install the delegation ...
562 my $associated_class = $self->associated_class;
563 foreach my $handle (keys %handles) {
564 my $method_to_call = $handles{$handle};
565 my $class_name = $associated_class->name;
566 my $name = "${class_name}::${handle}";
568 (!$associated_class->has_method($handle))
569 || $self->throw_error("You cannot overwrite a locally defined method ($handle) with a delegation", method_name => $handle);
572 # handles is not allowed to delegate
573 # any of these methods, as they will
574 # override the ones in your class, which
575 # is almost certainly not what you want.
577 # FIXME warn when $handle was explicitly specified, but not if the source is a regex or something
578 #cluck("Not delegating method '$handle' because it is a core method") and
579 next if $class_name->isa("Moose::Object") and $handle =~ /^BUILD|DEMOLISH$/ || Moose::Object->can($handle);
581 my $method = $self->_make_delegation_method($handle, $method_to_call);
583 $self->associated_class->add_method($method->name, $method);
587 sub remove_delegation {
589 my %handles = $self->_canonicalize_handles;
590 my $associated_class = $self->associated_class;
591 foreach my $handle (keys %handles) {
592 $self->associated_class->remove_method($handle);
596 # private methods to help delegation ...
598 sub _canonicalize_handles {
600 my $handles = $self->handles;
601 if (my $handle_type = ref($handles)) {
602 if ($handle_type eq 'HASH') {
605 elsif ($handle_type eq 'ARRAY') {
606 return map { $_ => $_ } @{$handles};
608 elsif ($handle_type eq 'Regexp') {
609 ($self->has_type_constraint)
610 || $self->throw_error("Cannot delegate methods based on a Regexp without a type constraint (isa)", data => $handles);
611 return map { ($_ => $_) }
612 grep { /$handles/ } $self->_get_delegate_method_list;
614 elsif ($handle_type eq 'CODE') {
615 return $handles->($self, $self->_find_delegate_metaclass);
618 $self->throw_error("Unable to canonicalize the 'handles' option with $handles", data => $handles);
622 Class::MOP::load_class($handles);
623 my $role_meta = Class::MOP::class_of($handles);
625 (blessed $role_meta && $role_meta->isa('Moose::Meta::Role'))
626 || $self->throw_error("Unable to canonicalize the 'handles' option with $handles because its metaclass is not a Moose::Meta::Role", data => $handles);
628 return map { $_ => $_ } (
629 $role_meta->get_method_list,
630 map { $_->name } $role_meta->get_required_method_list,
635 sub _find_delegate_metaclass {
637 if (my $class = $self->_isa_metadata) {
638 # we might be dealing with a non-Moose class,
639 # and need to make our own metaclass. if there's
640 # already a metaclass, it will be returned
641 return Moose::Meta::Class->initialize($class);
643 elsif (my $role = $self->_does_metadata) {
644 return Class::MOP::class_of($role);
647 $self->throw_error("Cannot find delegate metaclass for attribute " . $self->name);
651 sub _get_delegate_method_list {
653 my $meta = $self->_find_delegate_metaclass;
654 if ($meta->isa('Class::MOP::Class')) {
655 return map { $_->name } # NOTE: !never! delegate &meta
656 grep { $_->package_name ne 'Moose::Object' && $_->name ne 'meta' }
657 $meta->get_all_methods;
659 elsif ($meta->isa('Moose::Meta::Role')) {
660 return $meta->get_method_list;
663 $self->throw_error("Unable to recognize the delegate metaclass '$meta'", data => $meta);
667 sub delegation_metaclass { 'Moose::Meta::Method::Delegation' }
669 sub _make_delegation_method {
670 my ( $self, $handle_name, $method_to_call ) = @_;
674 $method_body = $method_to_call
675 if 'CODE' eq ref($method_to_call);
677 return $self->delegation_metaclass->new(
678 name => $handle_name,
679 package_name => $self->associated_class->name,
681 delegate_to_method => $method_to_call,
685 sub _coerce_and_verify {
688 my $instance = shift;
690 return $val unless $self->has_type_constraint;
692 my $type_constraint = $self->type_constraint;
693 if ($self->should_coerce && $type_constraint->has_coercion) {
694 $val = $type_constraint->coerce($val);
697 $self->verify_against_type_constraint($val, instance => $instance);
702 sub verify_against_type_constraint {
706 return 1 if !$self->has_type_constraint;
708 my $type_constraint = $self->type_constraint;
710 $type_constraint->check($val)
711 || $self->throw_error("Attribute ("
713 . ") does not pass the type constraint because: "
714 . $type_constraint->get_message($val), data => $val, @_);
717 package Moose::Meta::Attribute::Custom::Moose;
718 sub register_implementation { 'Moose::Meta::Attribute' }
728 Moose::Meta::Attribute - The Moose attribute metaclass
732 This class is a subclass of L<Class::MOP::Attribute> that provides
733 additional Moose-specific functionality.
735 To really understand this class, you will need to start with the
736 L<Class::MOP::Attribute> documentation. This class can be understood
737 as a set of additional features on top of the basic feature provided
738 by that parent class.
742 C<Moose::Meta::Attribute> is a subclass of L<Class::MOP::Attribute>.
746 Many of the documented below override methods in
747 L<Class::MOP::Attribute> and add Moose specific features.
753 =item B<< Moose::Meta::Attribute->new(%options) >>
755 This method overrides the L<Class::MOP::Attribute> constructor.
757 Many of the options below are described in more detail in the
758 L<Moose::Manual::Attributes> document.
760 It adds the following options to the constructor:
764 =item * is => 'ro' or 'rw'
766 This provides a shorthand for specifying the C<reader>, C<writer>, or
767 C<accessor> names. If the attribute is read-only ('ro') then it will
768 have a C<reader> method with the same attribute as the name.
770 If it is read-write ('rw') then it will have an C<accessor> method
771 with the same name. If you provide an explicit C<writer> for a
772 read-write attribute, then you will have a C<reader> with the same
773 name as the attribute, and a C<writer> with the name you provided.
777 This option accepts a type. The type can be a string, which should be
778 a type name. If the type name is unknown, it is assumed to be a class
781 This option can also accept a L<Moose::Meta::TypeConstraint> object.
783 If you I<also> provide a C<does> option, then your C<isa> option must
784 be a class name, and that class must do the role specified with
787 =item * does => $role
789 This is short-hand for saying that the attribute's type must be an
790 object which does the named role.
792 =item * coerce => $bool
794 This option is only valid for objects with a type constraint
795 (C<isa>). If this is true, then coercions will be applied whenever
796 this attribute is set.
798 You can make both this and the C<weak_ref> option true.
800 =item * trigger => $sub
802 This option accepts a subroutine reference, which will be called after
803 the attribute is set.
805 =item * required => $bool
807 An attribute which is required must be provided to the constructor. An
808 attribute which is required can also have a C<default> or C<builder>,
809 which will satisfy its required-ness.
811 A required attribute must have a C<default>, C<builder> or a
812 non-C<undef> C<init_arg>
814 =item * lazy => $bool
816 A lazy attribute must have a C<default> or C<builder>. When an
817 attribute is lazy, the default value will not be calculated until the
820 =item * weak_ref => $bool
822 If this is true, the attribute's value will be stored as a weak
825 =item * auto_deref => $bool
827 If this is true, then the reader will dereference the value when it is
828 called. The attribute must have a type constraint which defines the
829 attribute as an array or hash reference.
831 =item * lazy_build => $bool
833 Setting this to true makes the attribute lazy and provides a number of
841 is equivalent to this:
846 builder => '_build_size',
847 clearer => 'clear_size',
848 predicate => 'has_size',
851 =item * documentation
853 An arbitrary string that can be retrieved later by calling C<<
854 $attr->documentation >>.
858 =item B<< $attr->clone(%options) >>
860 This creates a new attribute based on attribute being cloned. You must
861 supply a C<name> option to provide a new name for the attribute.
863 The C<%options> can only specify options handled by
864 L<Class::MOP::Attribute>.
868 =head2 Value management
872 =item B<< $attr->initialize_instance_slot($meta_instance, $instance, $params) >>
874 This method is used internally to initialize the attribute's slot in
875 the object C<$instance>.
877 This overrides the L<Class::MOP::Attribute> method to handle lazy
878 attributes, weak references, and type constraints.
884 eval { $point->meta->get_attribute('x')->set_value($point, 'forty-two') };
889 I<Attribute (x) does not pass the type constraint (Int) with 'forty-two'>
891 Before setting the value, a check is made on the type constraint of
892 the attribute, if it has one, to see if the value passes it. If the
893 value fails to pass, the set operation dies with a L<throw_error>.
895 Any coercion to convert values is done before checking the type constraint.
897 To check a value against a type constraint before setting it, fetch the
898 attribute instance using L<Class::MOP::Class/find_attribute_by_name>,
899 fetch the type_constraint from the attribute using L<Moose::Meta::Attribute/type_constraint>
900 and call L<Moose::Meta::TypeConstraint/check>. See L<Moose::Cookbook::Basics::Recipe4>
905 =head2 Attribute Accessor generation
909 =item B<< $attr->install_accessors >>
911 This method overrides the parent to also install delegation methods.
913 =item B<< $attr->remove_accessors >>
915 This method overrides the parent to also remove delegation methods.
917 =item B<< $attr->install_delegation >>
919 This method adds its delegation methods to the attribute's associated
920 class, if it has any to add.
922 =item B<< $attr->remove_delegation >>
924 This method remove its delegation methods from the attribute's
927 =item B<< $attr->accessor_metaclass >>
929 Returns the accessor metaclass name, which defaults to
930 L<Moose::Meta::Method::Accessor>.
932 =item B<< $attr->delegation_metaclass >>
934 Returns the delegation metaclass name, which defaults to
935 L<Moose::Meta::Method::Delegation>.
939 =head2 Additional Moose features
941 These methods are not found in the superclass. They support features
946 =item B<< $attr->does($role) >>
948 This indicates whether the I<attribute itself> does the given
949 role. The role can be given as a full class name, or as a resolvable
952 Note that this checks the attribute itself, not its type constraint,
953 so it is checking the attribute's metaclass and any traits applied to
956 =item B<< Moose::Meta::Class->interpolate_class_and_new($name, %options) >>
958 This is an alternate constructor that handles the C<metaclass> and
961 Effectively, this method is a factory that finds or creates the
962 appropriate class for the given C<metaclass> and/or C<traits>.
964 Once it has the appropriate class, it will call C<< $class->new($name,
965 %options) >> on that class.
967 =item B<< $attr->clone_and_inherit_options(%options) >>
969 This method supports the C<has '+foo'> feature. It does various bits
970 of processing on the supplied C<%options> before ultimately calling
973 One of its main tasks is to make sure that the C<%options> provided
974 only includes the options returned by the
975 C<legal_options_for_inheritance> method.
977 =item B<< $attr->legal_options_for_inheritance >>
979 This returns a whitelist of options that can be overridden in a
980 subclass's attribute definition.
982 This exists to allow a custom metaclass to change or add to the list
983 of options which can be changed.
985 =item B<< $attr->type_constraint >>
987 Returns the L<Moose::Meta::TypeConstraint> object for this attribute,
990 =item B<< $attr->has_type_constraint >>
992 Returns true if this attribute has a type constraint.
994 =item B<< $attr->verify_against_type_constraint($value) >>
996 Given a value, this method returns true if the value is valid for the
997 attribute's type constraint. If the value is not valid, it throws an
1000 =item B<< $attr->handles >>
1002 This returns the value of the C<handles> option passed to the
1005 =item B<< $attr->has_handles >>
1007 Returns true if this attribute performs delegation.
1009 =item B<< $attr->is_weak_ref >>
1011 Returns true if this attribute stores its value as a weak reference.
1013 =item B<< $attr->is_required >>
1015 Returns true if this attribute is required to have a value.
1017 =item B<< $attr->is_lazy >>
1019 Returns true if this attribute is lazy.
1021 =item B<< $attr->is_lazy_build >>
1023 Returns true if the C<lazy_build> option was true when passed to the
1026 =item B<< $attr->should_coerce >>
1028 Returns true if the C<coerce> option passed to the constructor was
1031 =item B<< $attr->should_auto_deref >>
1033 Returns true if the C<auto_deref> option passed to the constructor was
1036 =item B<< $attr->trigger >>
1038 This is the subroutine reference that was in the C<trigger> option
1039 passed to the constructor, if any.
1041 =item B<< $attr->has_trigger >>
1043 Returns true if this attribute has a trigger set.
1045 =item B<< $attr->documentation >>
1047 Returns the value that was in the C<documentation> option passed to
1048 the constructor, if any.
1050 =item B<< $attr->has_documentation >>
1052 Returns true if this attribute has any documentation.
1054 =item B<< $attr->applied_traits >>
1056 This returns an array reference of all the traits which were applied
1057 to this attribute. If none were applied, this returns C<undef>.
1059 =item B<< $attr->has_applied_traits >>
1061 Returns true if this attribute has any traits applied.
1067 All complex software has bugs lurking in it, and this module is no
1068 exception. If you find a bug please either email me, or add the bug
1073 Stevan Little E<lt>stevan@iinteractive.comE<gt>
1075 Yuval Kogman E<lt>nothingmuch@woobling.comE<gt>
1077 =head1 COPYRIGHT AND LICENSE
1079 Copyright 2006-2009 by Infinity Interactive, Inc.
1081 L<http://www.iinteractive.com>
1083 This library is free software; you can redistribute it and/or modify
1084 it under the same terms as Perl itself.