2 package Moose::Meta::Attribute;
9 use Scalar::Util 'blessed', 'weaken';
10 use List::MoreUtils 'any';
14 use Moose::Deprecated;
15 use Moose::Meta::Method::Accessor;
16 use Moose::Meta::Method::Delegation;
18 use Moose::Util::TypeConstraints ();
19 use Class::MOP::MiniTrait;
21 use base 'Class::MOP::Attribute', 'Moose::Meta::Mixin::AttributeCore';
23 Class::MOP::MiniTrait::apply(__PACKAGE__, 'Moose::Meta::Object::Trait');
25 __PACKAGE__->meta->add_attribute('traits' => (
26 reader => 'applied_traits',
27 predicate => 'has_applied_traits',
28 Class::MOP::_definition_context(),
31 # we need to have a ->does method in here to
32 # more easily support traits, and the introspection
33 # of those traits. We extend the does check to look
34 # for metatrait aliases.
36 my ($self, $role_name) = @_;
38 Moose::Util::resolve_metatrait_alias(Attribute => $role_name)
40 return 0 if !defined($name); # failed to load class
41 return $self->Moose::Object::does($name);
46 require Moose::Meta::Class;
47 ( ref $self && $self->associated_class ) || "Moose::Meta::Class";
52 my $inv = $self->_error_thrower;
53 unshift @_, "message" if @_ % 2 == 1;
54 unshift @_, attr => $self if ref $self;
56 my $handler = $inv->can("throw_error"); # to avoid incrementing depth by 1
60 sub _inline_throw_error {
61 my ( $self, $msg, $args ) = @_;
63 my $inv = $self->_error_thrower;
65 $inv = 'Moose::Meta::Class' unless $inv->can('_inline_throw_error');
68 my $class = $self->associated_class;
70 my $class_name = B::perlstring($class->name);
71 my $attr_name = B::perlstring($self->name);
72 $args = 'attr => Class::MOP::class_of(' . $class_name . ')'
73 . '->find_attribute_by_name(' . $attr_name . '), '
74 . (defined $args ? $args : '');
77 return $inv->_inline_throw_error($msg, $args)
81 my ($class, $name, %options) = @_;
82 $class->_process_options($name, \%options) unless $options{__hack_no_process_options}; # used from clone()... YECHKKK FIXME ICKY YUCK GROSS
84 delete $options{__hack_no_process_options};
89 map { $_->init_arg() }
90 $class->meta()->get_all_attributes()
93 my @bad = sort grep { ! $attrs{$_} } keys %options;
97 Carp::cluck "Found unknown argument(s) passed to '$name' attribute constructor in '$class': @bad";
100 return $class->SUPER::new($name, %options);
103 sub interpolate_class_and_new {
104 my ($class, $name, %args) = @_;
106 my ( $new_class, @traits ) = $class->interpolate_class(\%args);
108 $new_class->new($name, %args, ( scalar(@traits) ? ( traits => \@traits ) : () ) );
111 sub interpolate_class {
112 my ($class, $options) = @_;
114 $class = ref($class) || $class;
116 if ( my $metaclass_name = delete $options->{metaclass} ) {
117 my $new_class = Moose::Util::resolve_metaclass_alias( Attribute => $metaclass_name );
119 if ( $class ne $new_class ) {
120 if ( $new_class->can("interpolate_class") ) {
121 return $new_class->interpolate_class($options);
130 if (my $traits = $options->{traits}) {
132 while ($i < @$traits) {
133 my $trait = $traits->[$i++];
134 next if ref($trait); # options to a trait we discarded
136 $trait = Moose::Util::resolve_metatrait_alias(Attribute => $trait)
139 next if $class->does($trait);
141 push @traits, $trait;
144 push @traits, $traits->[$i++]
145 if $traits->[$i] && ref($traits->[$i]);
149 my $anon_class = Moose::Meta::Class->create_anon_class(
150 superclasses => [ $class ],
151 roles => [ @traits ],
155 $class = $anon_class->name;
159 return ( wantarray ? ( $class, @traits ) : $class );
164 # method-generating options shouldn't be overridden
165 sub illegal_options_for_inheritance {
166 qw(reader writer accessor clearer predicate)
170 # This method *must* be able to handle
171 # Class::MOP::Attribute instances as
172 # well. Yes, I know that is wrong, but
173 # apparently we didn't realize it was
174 # doing that and now we have some code
175 # which is dependent on it. The real
176 # solution of course is to push this
177 # feature back up into Class::MOP::Attribute
178 # but I not right now, I am too lazy.
179 # However if you are reading this and
180 # looking for something to do,.. please
183 sub clone_and_inherit_options {
184 my ($self, %options) = @_;
187 # we may want to extends a Class::MOP::Attribute
188 # in which case we need to be able to use the
189 # core set of legal options that have always
190 # been here. But we allows Moose::Meta::Attribute
191 # instances to changes them.
193 my @illegal_options = $self->can('illegal_options_for_inheritance')
194 ? $self->illegal_options_for_inheritance
197 my @found_illegal_options = grep { exists $options{$_} && exists $self->{$_} ? $_ : undef } @illegal_options;
198 (scalar @found_illegal_options == 0)
199 || $self->throw_error("Illegal inherited options => (" . (join ', ' => @found_illegal_options) . ")", data => \%options);
203 if (blessed($options{isa}) && $options{isa}->isa('Moose::Meta::TypeConstraint')) {
204 $type_constraint = $options{isa};
207 $type_constraint = Moose::Util::TypeConstraints::find_or_create_isa_type_constraint($options{isa});
208 (defined $type_constraint)
209 || $self->throw_error("Could not find the type constraint '" . $options{isa} . "'", data => $options{isa});
212 $options{type_constraint} = $type_constraint;
215 if ($options{does}) {
217 if (blessed($options{does}) && $options{does}->isa('Moose::Meta::TypeConstraint')) {
218 $type_constraint = $options{does};
221 $type_constraint = Moose::Util::TypeConstraints::find_or_create_does_type_constraint($options{does});
222 (defined $type_constraint)
223 || $self->throw_error("Could not find the type constraint '" . $options{does} . "'", data => $options{does});
226 $options{type_constraint} = $type_constraint;
230 # this doesn't apply to Class::MOP::Attributes,
231 # so we can ignore it for them.
233 if ($self->can('interpolate_class')) {
234 ( $options{metaclass}, my @traits ) = $self->interpolate_class(\%options);
237 my @all_traits = grep { $seen{$_}++ } @{ $self->applied_traits || [] }, @traits;
238 $options{traits} = \@all_traits if @all_traits;
241 # This method can be called on a CMOP::Attribute object, so we need to
242 # make sure we can call this method.
243 $self->_process_lazy_build_option( $self->name, \%options )
244 if $self->can('_process_lazy_build_option');
246 $self->clone(%options);
250 my ( $self, %params ) = @_;
252 my $class = delete $params{metaclass} || ref $self;
254 my ( @init, @non_init );
256 foreach my $attr ( grep { $_->has_value($self) } Class::MOP::class_of($self)->get_all_attributes ) {
257 push @{ $attr->has_init_arg ? \@init : \@non_init }, $attr;
260 my %new_params = ( ( map { $_->init_arg => $_->get_value($self) } @init ), %params );
262 my $name = delete $new_params{name};
264 my $clone = $class->new($name, %new_params, __hack_no_process_options => 1 );
266 foreach my $attr ( @non_init ) {
267 $attr->set_value($clone, $attr->get_value($self));
273 sub _process_options {
274 my ( $class, $name, $options ) = @_;
276 $class->_process_is_option( $name, $options );
277 $class->_process_isa_option( $name, $options );
278 $class->_process_does_option( $name, $options );
279 $class->_process_coerce_option( $name, $options );
280 $class->_process_trigger_option( $name, $options );
281 $class->_process_auto_deref_option( $name, $options );
282 $class->_process_lazy_build_option( $name, $options );
283 $class->_process_lazy_option( $name, $options );
284 $class->_process_required_option( $name, $options );
287 sub _process_is_option {
288 my ( $class, $name, $options ) = @_;
290 return unless $options->{is};
292 ### -------------------------
293 ## is => ro, writer => _foo # turns into (reader => foo, writer => _foo) as before
294 ## is => rw, writer => _foo # turns into (reader => foo, writer => _foo)
295 ## is => rw, accessor => _foo # turns into (accessor => _foo)
296 ## is => ro, accessor => _foo # error, accesor is rw
297 ### -------------------------
299 if ( $options->{is} eq 'ro' ) {
301 "Cannot define an accessor name on a read-only attribute, accessors are read/write",
303 if exists $options->{accessor};
304 $options->{reader} ||= $name;
306 elsif ( $options->{is} eq 'rw' ) {
307 if ( $options->{writer} ) {
308 $options->{reader} ||= $name;
311 $options->{accessor} ||= $name;
314 elsif ( $options->{is} eq 'bare' ) {
316 # do nothing, but don't complain (later) about missing methods
319 $class->throw_error( "I do not understand this option (is => "
321 . ") on attribute ($name)", data => $options->{is} );
325 sub _process_isa_option {
326 my ( $class, $name, $options ) = @_;
328 return unless exists $options->{isa};
330 if ( exists $options->{does} ) {
331 if ( try { $options->{isa}->can('does') } ) {
332 ( $options->{isa}->does( $options->{does} ) )
333 || $class->throw_error(
334 "Cannot have an isa option and a does option if the isa does not do the does on attribute ($name)",
339 "Cannot have an isa option which cannot ->does() on attribute ($name)",
344 # allow for anon-subtypes here ...
345 if ( blessed( $options->{isa} )
346 && $options->{isa}->isa('Moose::Meta::TypeConstraint') ) {
347 $options->{type_constraint} = $options->{isa};
350 $options->{type_constraint}
351 = Moose::Util::TypeConstraints::find_or_create_isa_type_constraint(
356 sub _process_does_option {
357 my ( $class, $name, $options ) = @_;
359 return unless exists $options->{does} && ! exists $options->{isa};
361 # allow for anon-subtypes here ...
362 if ( blessed( $options->{does} )
363 && $options->{does}->isa('Moose::Meta::TypeConstraint') ) {
364 $options->{type_constraint} = $options->{does};
367 $options->{type_constraint}
368 = Moose::Util::TypeConstraints::find_or_create_does_type_constraint(
373 sub _process_coerce_option {
374 my ( $class, $name, $options ) = @_;
376 return unless $options->{coerce};
378 ( exists $options->{type_constraint} )
379 || $class->throw_error(
380 "You cannot have coercion without specifying a type constraint on attribute ($name)",
384 "You cannot have a weak reference to a coerced value on attribute ($name)",
386 if $options->{weak_ref};
388 unless ( $options->{type_constraint}->has_coercion ) {
389 my $type = $options->{type_constraint}->name;
391 Moose::Deprecated::deprecated(
392 feature => 'coerce without coercion',
394 "You cannot coerce an attribute ($name) unless its type ($type) has a coercion"
399 sub _process_trigger_option {
400 my ( $class, $name, $options ) = @_;
402 return unless exists $options->{trigger};
404 ( 'CODE' eq ref $options->{trigger} )
405 || $class->throw_error("Trigger must be a CODE ref on attribute ($name)", data => $options->{trigger});
408 sub _process_auto_deref_option {
409 my ( $class, $name, $options ) = @_;
411 return unless $options->{auto_deref};
413 ( exists $options->{type_constraint} )
414 || $class->throw_error(
415 "You cannot auto-dereference without specifying a type constraint on attribute ($name)",
418 ( $options->{type_constraint}->is_a_type_of('ArrayRef')
419 || $options->{type_constraint}->is_a_type_of('HashRef') )
420 || $class->throw_error(
421 "You cannot auto-dereference anything other than a ArrayRef or HashRef on attribute ($name)",
425 sub _process_lazy_build_option {
426 my ( $class, $name, $options ) = @_;
428 return unless $options->{lazy_build};
431 "You can not use lazy_build and default for the same attribute ($name)",
433 if exists $options->{default};
435 $options->{lazy} = 1;
436 $options->{builder} ||= "_build_${name}";
438 if ( $name =~ /^_/ ) {
439 $options->{clearer} ||= "_clear${name}";
440 $options->{predicate} ||= "_has${name}";
443 $options->{clearer} ||= "clear_${name}";
444 $options->{predicate} ||= "has_${name}";
448 sub _process_lazy_option {
449 my ( $class, $name, $options ) = @_;
451 return unless $options->{lazy};
453 ( exists $options->{default} || defined $options->{builder} )
454 || $class->throw_error(
455 "You cannot have a lazy attribute ($name) without specifying a default value for it",
459 sub _process_required_option {
460 my ( $class, $name, $options ) = @_;
465 ( !exists $options->{init_arg} || defined $options->{init_arg} )
466 || exists $options->{default}
467 || defined $options->{builder}
471 "You cannot have a required attribute ($name) without a default, builder, or an init_arg",
476 sub initialize_instance_slot {
477 my ($self, $meta_instance, $instance, $params) = @_;
478 my $init_arg = $self->init_arg();
479 # try to fetch the init arg from the %params ...
483 if ( defined($init_arg) and exists $params->{$init_arg}) {
484 $val = $params->{$init_arg};
488 # skip it if it's lazy
489 return if $self->is_lazy;
490 # and die if it's required and doesn't have a default value
491 $self->throw_error("Attribute (" . $self->name . ") is required", object => $instance, data => $params)
492 if $self->is_required && !$self->has_default && !$self->has_builder;
494 # if nothing was in the %params, we can use the
495 # attribute's default value (if it has one)
496 if ($self->has_default) {
497 $val = $self->default($instance);
500 elsif ($self->has_builder) {
501 $val = $self->_call_builder($instance);
506 return unless $value_is_set;
508 $val = $self->_coerce_and_verify( $val, $instance );
510 $self->set_initial_value($instance, $val);
512 if ( ref $val && $self->is_weak_ref ) {
513 $self->_weaken_value($instance);
518 my ( $self, $instance ) = @_;
520 my $builder = $self->builder();
522 return $instance->$builder()
523 if $instance->can( $self->builder );
525 $self->throw_error( blessed($instance)
526 . " does not support builder method '"
528 . "' for attribute '"
537 sub _make_initializer_writer_callback {
539 my ($meta_instance, $instance, $slot_name) = @_;
540 my $old_callback = $self->SUPER::_make_initializer_writer_callback(@_);
542 $old_callback->($self->_coerce_and_verify($_[0], $instance));
547 my ($self, $instance, @args) = @_;
548 my $value = $args[0];
550 my $attr_name = quotemeta($self->name);
552 if ($self->is_required and not @args) {
553 $self->throw_error("Attribute ($attr_name) is required", object => $instance);
556 $value = $self->_coerce_and_verify( $value, $instance );
559 if ( $self->has_trigger && $self->has_value($instance) ) {
560 @old = $self->get_value($instance, 'for trigger');
563 $self->SUPER::set_value($instance, $value);
565 if ( ref $value && $self->is_weak_ref ) {
566 $self->_weaken_value($instance);
569 if ($self->has_trigger) {
570 $self->trigger->($instance, $value, @old);
574 sub _inline_set_value {
576 my ($instance, $value, $tc, $coercion, $message, $for_constructor) = @_;
580 $tc ||= '$type_constraint';
581 $coercion ||= '$type_coercion';
582 $message ||= '$type_message';
585 if ($self->_writer_value_needs_copy) {
586 push @code, $self->_inline_copy_value($value, $copy);
590 # constructors already handle required checks
591 push @code, $self->_inline_check_required
592 unless $for_constructor;
594 push @code, $self->_inline_tc_code($value, $tc, $coercion, $message);
596 # constructors do triggers all at once at the end
597 push @code, $self->_inline_get_old_value_for_trigger($instance, $old)
598 unless $for_constructor;
601 $self->SUPER::_inline_set_value($instance, $value),
602 $self->_inline_weaken_value($instance, $value),
605 # constructors do triggers all at once at the end
606 push @code, $self->_inline_trigger($instance, $value, $old)
607 unless $for_constructor;
612 sub _writer_value_needs_copy {
614 return $self->should_coerce;
617 sub _inline_copy_value {
619 my ($value, $copy) = @_;
621 return 'my ' . $copy . ' = ' . $value . ';'
624 sub _inline_check_required {
627 return unless $self->is_required;
629 my $attr_name = quotemeta($self->name);
633 $self->_inline_throw_error(
634 '"Attribute (' . $attr_name . ') is required, so cannot '
635 . 'be set to undef"' # defined $_[1] is not good enough
641 sub _inline_tc_code {
643 my ($value, $tc, $coercion, $message, $is_lazy) = @_;
645 $self->_inline_check_coercion(
646 $value, $tc, $coercion, $is_lazy,
648 $self->_inline_check_constraint(
649 $value, $tc, $message, $is_lazy,
654 sub _inline_check_coercion {
656 my ($value, $tc, $coercion) = @_;
658 return unless $self->should_coerce && $self->type_constraint->has_coercion;
660 if ( $self->type_constraint->can_be_inlined ) {
662 'if (! (' . $self->type_constraint->_inline_check($value) . ')) {',
663 $value . ' = ' . $coercion . '->(' . $value . ');',
669 'if (!' . $tc . '->(' . $value . ')) {',
670 $value . ' = ' . $coercion . '->(' . $value . ');',
676 sub _inline_check_constraint {
678 my ($value, $tc, $message) = @_;
680 return unless $self->has_type_constraint;
682 my $attr_name = quotemeta($self->name);
684 if ( $self->type_constraint->can_be_inlined ) {
686 'if (! (' . $self->type_constraint->_inline_check($value) . ')) {',
687 $self->_inline_throw_error(
688 '"Attribute (' . $attr_name . ') does not pass the type '
689 . 'constraint because: " . '
690 . 'do { local $_ = ' . $value . '; '
691 . $message . '->(' . $value . ')'
700 'if (!' . $tc . '->(' . $value . ')) {',
701 $self->_inline_throw_error(
702 '"Attribute (' . $attr_name . ') does not pass the type '
703 . 'constraint because: " . '
704 . 'do { local $_ = ' . $value . '; '
705 . $message . '->(' . $value . ')'
714 sub _inline_get_old_value_for_trigger {
716 my ($instance, $old) = @_;
718 return unless $self->has_trigger;
721 'my ' . $old . ' = ' . $self->_inline_instance_has($instance),
722 '? ' . $self->_inline_instance_get($instance),
727 sub _inline_weaken_value {
729 my ($instance, $value) = @_;
731 return unless $self->is_weak_ref;
733 my $mi = $self->associated_class->get_meta_instance;
735 $mi->inline_weaken_slot_value($instance, $self->name, $value),
736 'if ref ' . $value . ';',
740 sub _inline_trigger {
742 my ($instance, $value, $old) = @_;
744 return unless $self->has_trigger;
746 return '$trigger->(' . $instance . ', ' . $value . ', ' . $old . ');';
750 my ( $self, $instance ) = @_;
752 my $meta_instance = Class::MOP::Class->initialize( blessed($instance) )
755 $meta_instance->weaken_slot_value( $instance, $self->name );
759 my ($self, $instance, $for_trigger) = @_;
761 if ($self->is_lazy) {
762 unless ($self->has_value($instance)) {
764 if ($self->has_default) {
765 $value = $self->default($instance);
766 } elsif ( $self->has_builder ) {
767 $value = $self->_call_builder($instance);
770 $value = $self->_coerce_and_verify( $value, $instance );
772 $self->set_initial_value($instance, $value);
776 if ( $self->should_auto_deref && ! $for_trigger ) {
778 my $type_constraint = $self->type_constraint;
780 if ($type_constraint->is_a_type_of('ArrayRef')) {
781 my $rv = $self->SUPER::get_value($instance);
782 return unless defined $rv;
783 return wantarray ? @{ $rv } : $rv;
785 elsif ($type_constraint->is_a_type_of('HashRef')) {
786 my $rv = $self->SUPER::get_value($instance);
787 return unless defined $rv;
788 return wantarray ? %{ $rv } : $rv;
791 $self->throw_error("Can not auto de-reference the type constraint '" . $type_constraint->name . "'", object => $instance, type_constraint => $type_constraint);
797 return $self->SUPER::get_value($instance);
801 sub _inline_get_value {
803 my ($instance, $tc, $coercion, $message) = @_;
805 my $slot_access = $self->_inline_instance_get($instance);
806 $tc ||= '$type_constraint';
807 $coercion ||= '$type_coercion';
808 $message ||= '$type_message';
811 $self->_inline_check_lazy($instance, $tc, $coercion, $message),
812 $self->_inline_return_auto_deref($slot_access),
816 sub _inline_check_lazy {
818 my ($instance, $tc, $coercion, $message) = @_;
820 return unless $self->is_lazy;
822 my $slot_exists = $self->_inline_instance_has($instance);
825 'if (!' . $slot_exists . ') {',
826 $self->_inline_init_from_default($instance, '$default', $tc, $coercion, $message, 'lazy'),
831 sub _inline_init_from_default {
833 my ($instance, $default, $tc, $coercion, $message, $for_lazy) = @_;
835 if (!($self->has_default || $self->has_builder)) {
837 'You cannot have a lazy attribute '
838 . '(' . $self->name . ') '
839 . 'without specifying a default value for it',
845 $self->_inline_generate_default($instance, $default),
846 # intentionally not using _inline_tc_code, since that can be overridden
847 # to do things like possibly only do member tc checks, which isn't
848 # appropriate for checking the result of a default
849 $self->has_type_constraint
850 ? ($self->_inline_check_coercion($default, $tc, $coercion, $for_lazy),
851 $self->_inline_check_constraint($default, $tc, $message, $for_lazy))
853 $self->_inline_init_slot($instance, $default),
857 sub _inline_generate_default {
859 my ($instance, $default) = @_;
861 if ($self->has_default) {
862 my $source = 'my ' . $default . ' = $attr_default';
863 $source .= '->(' . $instance . ')'
864 if $self->is_default_a_coderef;
865 return $source . ';';
867 elsif ($self->has_builder) {
868 my $builder = B::perlstring($self->builder);
869 my $builder_str = quotemeta($self->builder);
870 my $attr_name_str = quotemeta($self->name);
872 'my ' . $default . ';',
873 'if (my $builder = ' . $instance . '->can(' . $builder . ')) {',
874 $default . ' = ' . $instance . '->$builder;',
877 'my $class = ref(' . $instance . ') || ' . $instance . ';',
878 $self->_inline_throw_error(
879 '"$class does not support builder method '
880 . '\'' . $builder_str . '\' for attribute '
881 . '\'' . $attr_name_str . '\'"'
888 "Can't generate a default for " . $self->name
889 . " since no default or builder was specified"
894 sub _inline_init_slot {
896 my ($inv, $value) = @_;
898 if ($self->has_initializer) {
899 return '$attr->set_initial_value(' . $inv . ', ' . $value . ');';
902 return $self->_inline_instance_set($inv, $value) . ';';
906 sub _inline_return_auto_deref {
909 return 'return ' . $self->_auto_deref(@_) . ';';
914 my ($ref_value) = @_;
916 return $ref_value unless $self->should_auto_deref;
918 my $type_constraint = $self->type_constraint;
921 if ($type_constraint->is_a_type_of('ArrayRef')) {
924 elsif ($type_constraint->is_a_type_of('HashRef')) {
929 'Can not auto de-reference the type constraint \''
930 . $type_constraint->name
932 type_constraint => $type_constraint,
937 . '? ' . $sigil . '{ (' . $ref_value . ') || return } '
938 . ': (' . $ref_value . ')';
941 ## installing accessors
943 sub accessor_metaclass { 'Moose::Meta::Method::Accessor' }
945 sub install_accessors {
947 $self->SUPER::install_accessors(@_);
948 $self->install_delegation if $self->has_handles;
952 sub _check_associated_methods {
955 @{ $self->associated_methods }
956 || ($self->_is_metadata || '') eq 'bare'
959 'Attribute (' . $self->name . ') of class '
960 . $self->associated_class->name
961 . ' has no associated methods'
962 . ' (did you mean to provide an "is" argument?)'
968 sub _process_accessors {
970 my ($type, $accessor, $generate_as_inline_methods) = @_;
972 $accessor = ( keys %$accessor )[0] if ( ref($accessor) || '' ) eq 'HASH';
973 my $method = $self->associated_class->get_method($accessor);
976 && $method->isa('Class::MOP::Method::Accessor')
977 && $method->associated_attribute->name ne $self->name ) {
979 my $other_attr_name = $method->associated_attribute->name;
980 my $name = $self->name;
983 "You are overwriting an accessor ($accessor) for the $other_attr_name attribute"
984 . " with a new accessor method for the $name attribute" );
989 && !$method->isa('Class::MOP::Method::Accessor')
990 && ( !$self->definition_context
991 || $method->package_name eq $self->definition_context->{package} )
995 "You are overwriting a locally defined method ($accessor) with "
999 if ( !$self->associated_class->has_method($accessor)
1000 && $self->associated_class->has_package_symbol( '&' . $accessor ) ) {
1003 "You are overwriting a locally defined function ($accessor) with "
1007 $self->SUPER::_process_accessors(@_);
1010 sub remove_accessors {
1012 $self->SUPER::remove_accessors(@_);
1013 $self->remove_delegation if $self->has_handles;
1017 sub install_delegation {
1021 # Here we canonicalize the 'handles' option
1022 # this will sort out any details and always
1023 # return an hash of methods which we want
1024 # to delagate to, see that method for details
1025 my %handles = $self->_canonicalize_handles;
1028 # install the delegation ...
1029 my $associated_class = $self->associated_class;
1030 foreach my $handle (keys %handles) {
1031 my $method_to_call = $handles{$handle};
1032 my $class_name = $associated_class->name;
1033 my $name = "${class_name}::${handle}";
1035 (!$associated_class->has_method($handle))
1036 || $self->throw_error("You cannot overwrite a locally defined method ($handle) with a delegation", method_name => $handle);
1039 # handles is not allowed to delegate
1040 # any of these methods, as they will
1041 # override the ones in your class, which
1042 # is almost certainly not what you want.
1044 # FIXME warn when $handle was explicitly specified, but not if the source is a regex or something
1045 #cluck("Not delegating method '$handle' because it is a core method") and
1046 next if $class_name->isa("Moose::Object") and $handle =~ /^BUILD|DEMOLISH$/ || Moose::Object->can($handle);
1048 my $method = $self->_make_delegation_method($handle, $method_to_call);
1050 $self->associated_class->add_method($method->name, $method);
1051 $self->associate_method($method);
1055 sub remove_delegation {
1057 my %handles = $self->_canonicalize_handles;
1058 my $associated_class = $self->associated_class;
1059 foreach my $handle (keys %handles) {
1060 next unless any { $handle eq $_ }
1062 @{ $self->associated_methods };
1063 $self->associated_class->remove_method($handle);
1067 # private methods to help delegation ...
1069 sub _canonicalize_handles {
1071 my $handles = $self->handles;
1072 if (my $handle_type = ref($handles)) {
1073 if ($handle_type eq 'HASH') {
1076 elsif ($handle_type eq 'ARRAY') {
1077 return map { $_ => $_ } @{$handles};
1079 elsif ($handle_type eq 'Regexp') {
1080 ($self->has_type_constraint)
1081 || $self->throw_error("Cannot delegate methods based on a Regexp without a type constraint (isa)", data => $handles);
1082 return map { ($_ => $_) }
1083 grep { /$handles/ } $self->_get_delegate_method_list;
1085 elsif ($handle_type eq 'CODE') {
1086 return $handles->($self, $self->_find_delegate_metaclass);
1088 elsif (blessed($handles) && $handles->isa('Moose::Meta::TypeConstraint::DuckType')) {
1089 return map { $_ => $_ } @{ $handles->methods };
1091 elsif (blessed($handles) && $handles->isa('Moose::Meta::TypeConstraint::Role')) {
1092 $handles = $handles->role;
1095 $self->throw_error("Unable to canonicalize the 'handles' option with $handles", data => $handles);
1099 Class::MOP::load_class($handles);
1100 my $role_meta = Class::MOP::class_of($handles);
1102 (blessed $role_meta && $role_meta->isa('Moose::Meta::Role'))
1103 || $self->throw_error("Unable to canonicalize the 'handles' option with $handles because its metaclass is not a Moose::Meta::Role", data => $handles);
1105 return map { $_ => $_ }
1107 grep { !$_->isa('Class::MOP::Method::Meta') } (
1108 $role_meta->_get_local_methods,
1109 $role_meta->get_required_method_list,
1113 sub _get_delegate_method_list {
1115 my $meta = $self->_find_delegate_metaclass;
1116 if ($meta->isa('Class::MOP::Class')) {
1117 return map { $_->name } # NOTE: !never! delegate &meta
1118 grep { $_->package_name ne 'Moose::Object' && !$_->isa('Class::MOP::Method::Meta') }
1119 $meta->get_all_methods;
1121 elsif ($meta->isa('Moose::Meta::Role')) {
1122 return $meta->get_method_list;
1125 $self->throw_error("Unable to recognize the delegate metaclass '$meta'", data => $meta);
1129 sub _find_delegate_metaclass {
1131 if (my $class = $self->_isa_metadata) {
1132 unless ( Class::MOP::is_class_loaded($class) ) {
1135 'The %s attribute is trying to delegate to a class which has not been loaded - %s',
1140 # we might be dealing with a non-Moose class,
1141 # and need to make our own metaclass. if there's
1142 # already a metaclass, it will be returned
1143 return Class::MOP::Class->initialize($class);
1145 elsif (my $role = $self->_does_metadata) {
1146 unless ( Class::MOP::is_class_loaded($class) ) {
1149 'The %s attribute is trying to delegate to a role which has not been loaded - %s',
1155 return Class::MOP::class_of($role);
1158 $self->throw_error("Cannot find delegate metaclass for attribute " . $self->name);
1162 sub delegation_metaclass { 'Moose::Meta::Method::Delegation' }
1164 sub _make_delegation_method {
1165 my ( $self, $handle_name, $method_to_call ) = @_;
1167 my @curried_arguments;
1169 ($method_to_call, @curried_arguments) = @$method_to_call
1170 if 'ARRAY' eq ref($method_to_call);
1172 return $self->delegation_metaclass->new(
1173 name => $handle_name,
1174 package_name => $self->associated_class->name,
1176 delegate_to_method => $method_to_call,
1177 curried_arguments => \@curried_arguments,
1181 sub _coerce_and_verify {
1184 my $instance = shift;
1186 return $val unless $self->has_type_constraint;
1188 $val = $self->type_constraint->coerce($val)
1189 if $self->should_coerce && $self->type_constraint->has_coercion;
1191 $self->verify_against_type_constraint($val, instance => $instance);
1196 sub verify_against_type_constraint {
1200 return 1 if !$self->has_type_constraint;
1202 my $type_constraint = $self->type_constraint;
1204 $type_constraint->check($val)
1205 || $self->throw_error("Attribute ("
1207 . ") does not pass the type constraint because: "
1208 . $type_constraint->get_message($val), data => $val, @_);
1211 package Moose::Meta::Attribute::Custom::Moose;
1212 sub register_implementation { 'Moose::Meta::Attribute' }
1216 # ABSTRACT: The Moose attribute metaclass
1224 This class is a subclass of L<Class::MOP::Attribute> that provides
1225 additional Moose-specific functionality.
1227 To really understand this class, you will need to start with the
1228 L<Class::MOP::Attribute> documentation. This class can be understood
1229 as a set of additional features on top of the basic feature provided
1230 by that parent class.
1234 C<Moose::Meta::Attribute> is a subclass of L<Class::MOP::Attribute>.
1238 Many of the documented below override methods in
1239 L<Class::MOP::Attribute> and add Moose specific features.
1245 =item B<< Moose::Meta::Attribute->new(%options) >>
1247 This method overrides the L<Class::MOP::Attribute> constructor.
1249 Many of the options below are described in more detail in the
1250 L<Moose::Manual::Attributes> document.
1252 It adds the following options to the constructor:
1256 =item * is => 'ro', 'rw', 'bare'
1258 This provides a shorthand for specifying the C<reader>, C<writer>, or
1259 C<accessor> names. If the attribute is read-only ('ro') then it will
1260 have a C<reader> method with the same attribute as the name.
1262 If it is read-write ('rw') then it will have an C<accessor> method
1263 with the same name. If you provide an explicit C<writer> for a
1264 read-write attribute, then you will have a C<reader> with the same
1265 name as the attribute, and a C<writer> with the name you provided.
1267 Use 'bare' when you are deliberately not installing any methods
1268 (accessor, reader, etc.) associated with this attribute; otherwise,
1269 Moose will issue a deprecation warning when this attribute is added to a
1272 =item * isa => $type
1274 This option accepts a type. The type can be a string, which should be
1275 a type name. If the type name is unknown, it is assumed to be a class
1278 This option can also accept a L<Moose::Meta::TypeConstraint> object.
1280 If you I<also> provide a C<does> option, then your C<isa> option must
1281 be a class name, and that class must do the role specified with
1284 =item * does => $role
1286 This is short-hand for saying that the attribute's type must be an
1287 object which does the named role.
1289 =item * coerce => $bool
1291 This option is only valid for objects with a type constraint
1292 (C<isa>) that defined a coercion. If this is true, then coercions will be applied whenever
1293 this attribute is set.
1295 You can make both this and the C<weak_ref> option true.
1297 =item * trigger => $sub
1299 This option accepts a subroutine reference, which will be called after
1300 the attribute is set.
1302 =item * required => $bool
1304 An attribute which is required must be provided to the constructor. An
1305 attribute which is required can also have a C<default> or C<builder>,
1306 which will satisfy its required-ness.
1308 A required attribute must have a C<default>, C<builder> or a
1309 non-C<undef> C<init_arg>
1311 =item * lazy => $bool
1313 A lazy attribute must have a C<default> or C<builder>. When an
1314 attribute is lazy, the default value will not be calculated until the
1317 =item * weak_ref => $bool
1319 If this is true, the attribute's value will be stored as a weak
1322 =item * auto_deref => $bool
1324 If this is true, then the reader will dereference the value when it is
1325 called. The attribute must have a type constraint which defines the
1326 attribute as an array or hash reference.
1328 =item * lazy_build => $bool
1330 Setting this to true makes the attribute lazy and provides a number of
1338 is equivalent to this:
1343 builder => '_build_size',
1344 clearer => 'clear_size',
1345 predicate => 'has_size',
1349 If your attribute name starts with an underscore (C<_>), then the clearer
1350 and predicate will as well:
1362 builder => '_build__size',
1363 clearer => '_clear_size',
1364 predicate => '_has_size',
1367 Note the doubled underscore in the builder name. Internally, Moose
1368 simply prepends the attribute name with "_build_" to come up with the
1371 =item * documentation
1373 An arbitrary string that can be retrieved later by calling C<<
1374 $attr->documentation >>.
1378 =item B<< $attr->clone(%options) >>
1380 This creates a new attribute based on attribute being cloned. You must
1381 supply a C<name> option to provide a new name for the attribute.
1383 The C<%options> can only specify options handled by
1384 L<Class::MOP::Attribute>.
1388 =head2 Value management
1392 =item B<< $attr->initialize_instance_slot($meta_instance, $instance, $params) >>
1394 This method is used internally to initialize the attribute's slot in
1395 the object C<$instance>.
1397 This overrides the L<Class::MOP::Attribute> method to handle lazy
1398 attributes, weak references, and type constraints.
1404 eval { $point->meta->get_attribute('x')->set_value($point, 'forty-two') };
1409 I<Attribute (x) does not pass the type constraint (Int) with 'forty-two'>
1411 Before setting the value, a check is made on the type constraint of
1412 the attribute, if it has one, to see if the value passes it. If the
1413 value fails to pass, the set operation dies with a L</throw_error>.
1415 Any coercion to convert values is done before checking the type constraint.
1417 To check a value against a type constraint before setting it, fetch the
1418 attribute instance using L<Class::MOP::Class/find_attribute_by_name>,
1419 fetch the type_constraint from the attribute using L<Moose::Meta::Attribute/type_constraint>
1420 and call L<Moose::Meta::TypeConstraint/check>. See L<Moose::Cookbook::Basics::Recipe4>
1425 =head2 Attribute Accessor generation
1429 =item B<< $attr->install_accessors >>
1431 This method overrides the parent to also install delegation methods.
1433 If, after installing all methods, the attribute object has no associated
1434 methods, it throws an error unless C<< is => 'bare' >> was passed to the
1435 attribute constructor. (Trying to add an attribute that has no associated
1436 methods is almost always an error.)
1438 =item B<< $attr->remove_accessors >>
1440 This method overrides the parent to also remove delegation methods.
1442 =item B<< $attr->inline_set($instance_var, $value_var) >>
1444 This method return a code snippet suitable for inlining the relevant
1445 operation. It expect strings containing variable names to be used in the
1446 inlining, like C<'$self'> or C<'$_[1]'>.
1448 =item B<< $attr->install_delegation >>
1450 This method adds its delegation methods to the attribute's associated
1451 class, if it has any to add.
1453 =item B<< $attr->remove_delegation >>
1455 This method remove its delegation methods from the attribute's
1458 =item B<< $attr->accessor_metaclass >>
1460 Returns the accessor metaclass name, which defaults to
1461 L<Moose::Meta::Method::Accessor>.
1463 =item B<< $attr->delegation_metaclass >>
1465 Returns the delegation metaclass name, which defaults to
1466 L<Moose::Meta::Method::Delegation>.
1470 =head2 Additional Moose features
1472 These methods are not found in the superclass. They support features
1477 =item B<< $attr->does($role) >>
1479 This indicates whether the I<attribute itself> does the given
1480 role. The role can be given as a full class name, or as a resolvable
1483 Note that this checks the attribute itself, not its type constraint,
1484 so it is checking the attribute's metaclass and any traits applied to
1487 =item B<< Moose::Meta::Class->interpolate_class_and_new($name, %options) >>
1489 This is an alternate constructor that handles the C<metaclass> and
1492 Effectively, this method is a factory that finds or creates the
1493 appropriate class for the given C<metaclass> and/or C<traits>.
1495 Once it has the appropriate class, it will call C<< $class->new($name,
1496 %options) >> on that class.
1498 =item B<< $attr->clone_and_inherit_options(%options) >>
1500 This method supports the C<has '+foo'> feature. It does various bits
1501 of processing on the supplied C<%options> before ultimately calling
1502 the C<clone> method.
1504 One of its main tasks is to make sure that the C<%options> provided
1505 does not include the options returned by the
1506 C<illegal_options_for_inheritance> method.
1508 =item B<< $attr->illegal_options_for_inheritance >>
1510 This returns a blacklist of options that can not be overridden in a
1511 subclass's attribute definition.
1513 This exists to allow a custom metaclass to change or add to the list
1514 of options which can not be changed.
1516 =item B<< $attr->type_constraint >>
1518 Returns the L<Moose::Meta::TypeConstraint> object for this attribute,
1521 =item B<< $attr->has_type_constraint >>
1523 Returns true if this attribute has a type constraint.
1525 =item B<< $attr->verify_against_type_constraint($value) >>
1527 Given a value, this method returns true if the value is valid for the
1528 attribute's type constraint. If the value is not valid, it throws an
1531 =item B<< $attr->handles >>
1533 This returns the value of the C<handles> option passed to the
1536 =item B<< $attr->has_handles >>
1538 Returns true if this attribute performs delegation.
1540 =item B<< $attr->is_weak_ref >>
1542 Returns true if this attribute stores its value as a weak reference.
1544 =item B<< $attr->is_required >>
1546 Returns true if this attribute is required to have a value.
1548 =item B<< $attr->is_lazy >>
1550 Returns true if this attribute is lazy.
1552 =item B<< $attr->is_lazy_build >>
1554 Returns true if the C<lazy_build> option was true when passed to the
1557 =item B<< $attr->should_coerce >>
1559 Returns true if the C<coerce> option passed to the constructor was
1562 =item B<< $attr->should_auto_deref >>
1564 Returns true if the C<auto_deref> option passed to the constructor was
1567 =item B<< $attr->trigger >>
1569 This is the subroutine reference that was in the C<trigger> option
1570 passed to the constructor, if any.
1572 =item B<< $attr->has_trigger >>
1574 Returns true if this attribute has a trigger set.
1576 =item B<< $attr->documentation >>
1578 Returns the value that was in the C<documentation> option passed to
1579 the constructor, if any.
1581 =item B<< $attr->has_documentation >>
1583 Returns true if this attribute has any documentation.
1585 =item B<< $attr->applied_traits >>
1587 This returns an array reference of all the traits which were applied
1588 to this attribute. If none were applied, this returns C<undef>.
1590 =item B<< $attr->has_applied_traits >>
1592 Returns true if this attribute has any traits applied.
1598 See L<Moose/BUGS> for details on reporting bugs.