2 package Moose::Meta::Attribute;
8 use Scalar::Util 'blessed', 'weaken';
9 use List::MoreUtils 'any';
13 use Moose::Deprecated;
14 use Moose::Meta::Method::Accessor;
15 use Moose::Meta::Method::Delegation;
17 use Moose::Util::TypeConstraints ();
18 use Class::MOP::MiniTrait;
20 use base 'Class::MOP::Attribute', 'Moose::Meta::Mixin::AttributeCore';
22 Class::MOP::MiniTrait::apply(__PACKAGE__, 'Moose::Meta::Object::Trait');
24 __PACKAGE__->meta->add_attribute('traits' => (
25 reader => 'applied_traits',
26 predicate => 'has_applied_traits',
29 # we need to have a ->does method in here to
30 # more easily support traits, and the introspection
31 # of those traits. We extend the does check to look
32 # for metatrait aliases.
34 my ($self, $role_name) = @_;
36 Moose::Util::resolve_metatrait_alias(Attribute => $role_name)
38 return 0 if !defined($name); # failed to load class
39 return $self->Moose::Object::does($name);
44 my $class = ( ref $self && $self->associated_class ) || "Moose::Meta::Class";
45 unshift @_, "message" if @_ % 2 == 1;
46 unshift @_, attr => $self if ref $self;
48 my $handler = $class->can("throw_error"); # to avoid incrementing depth by 1
52 sub _inline_throw_error {
53 my ( $self, $msg, $args ) = @_;
54 "\$meta->throw_error($msg" . ($args ? ", $args" : "") . ")"; # FIXME makes deparsing *REALLY* hard
58 my ($class, $name, %options) = @_;
59 $class->_process_options($name, \%options) unless $options{__hack_no_process_options}; # used from clone()... YECHKKK FIXME ICKY YUCK GROSS
61 delete $options{__hack_no_process_options};
66 map { $_->init_arg() }
67 $class->meta()->get_all_attributes()
70 my @bad = sort grep { ! $attrs{$_} } keys %options;
74 Carp::cluck "Found unknown argument(s) passed to '$name' attribute constructor in '$class': @bad";
77 return $class->SUPER::new($name, %options);
80 sub interpolate_class_and_new {
81 my ($class, $name, %args) = @_;
83 my ( $new_class, @traits ) = $class->interpolate_class(\%args);
85 $new_class->new($name, %args, ( scalar(@traits) ? ( traits => \@traits ) : () ) );
88 sub interpolate_class {
89 my ($class, $options) = @_;
91 $class = ref($class) || $class;
93 if ( my $metaclass_name = delete $options->{metaclass} ) {
94 my $new_class = Moose::Util::resolve_metaclass_alias( Attribute => $metaclass_name );
96 if ( $class ne $new_class ) {
97 if ( $new_class->can("interpolate_class") ) {
98 return $new_class->interpolate_class($options);
107 if (my $traits = $options->{traits}) {
109 while ($i < @$traits) {
110 my $trait = $traits->[$i++];
111 next if ref($trait); # options to a trait we discarded
113 $trait = Moose::Util::resolve_metatrait_alias(Attribute => $trait)
116 next if $class->does($trait);
118 push @traits, $trait;
121 push @traits, $traits->[$i++]
122 if $traits->[$i] && ref($traits->[$i]);
126 my $anon_class = Moose::Meta::Class->create_anon_class(
127 superclasses => [ $class ],
128 roles => [ @traits ],
132 $class = $anon_class->name;
136 return ( wantarray ? ( $class, @traits ) : $class );
141 # method-generating options shouldn't be overridden
142 sub illegal_options_for_inheritance {
143 qw(reader writer accessor clearer predicate)
147 # This method *must* be able to handle
148 # Class::MOP::Attribute instances as
149 # well. Yes, I know that is wrong, but
150 # apparently we didn't realize it was
151 # doing that and now we have some code
152 # which is dependent on it. The real
153 # solution of course is to push this
154 # feature back up into Class::MOP::Attribute
155 # but I not right now, I am too lazy.
156 # However if you are reading this and
157 # looking for something to do,.. please
160 sub clone_and_inherit_options {
161 my ($self, %options) = @_;
164 # we may want to extends a Class::MOP::Attribute
165 # in which case we need to be able to use the
166 # core set of legal options that have always
167 # been here. But we allows Moose::Meta::Attribute
168 # instances to changes them.
170 my @illegal_options = $self->can('illegal_options_for_inheritance')
171 ? $self->illegal_options_for_inheritance
174 my @found_illegal_options = grep { exists $options{$_} && exists $self->{$_} ? $_ : undef } @illegal_options;
175 (scalar @found_illegal_options == 0)
176 || $self->throw_error("Illegal inherited options => (" . (join ', ' => @found_illegal_options) . ")", data => \%options);
180 if (blessed($options{isa}) && $options{isa}->isa('Moose::Meta::TypeConstraint')) {
181 $type_constraint = $options{isa};
184 $type_constraint = Moose::Util::TypeConstraints::find_or_create_isa_type_constraint($options{isa});
185 (defined $type_constraint)
186 || $self->throw_error("Could not find the type constraint '" . $options{isa} . "'", data => $options{isa});
189 $options{type_constraint} = $type_constraint;
192 if ($options{does}) {
194 if (blessed($options{does}) && $options{does}->isa('Moose::Meta::TypeConstraint')) {
195 $type_constraint = $options{does};
198 $type_constraint = Moose::Util::TypeConstraints::find_or_create_does_type_constraint($options{does});
199 (defined $type_constraint)
200 || $self->throw_error("Could not find the type constraint '" . $options{does} . "'", data => $options{does});
203 $options{type_constraint} = $type_constraint;
207 # this doesn't apply to Class::MOP::Attributes,
208 # so we can ignore it for them.
210 if ($self->can('interpolate_class')) {
211 ( $options{metaclass}, my @traits ) = $self->interpolate_class(\%options);
214 my @all_traits = grep { $seen{$_}++ } @{ $self->applied_traits || [] }, @traits;
215 $options{traits} = \@all_traits if @all_traits;
218 # This method can be called on a CMOP::Attribute object, so we need to
219 # make sure we can call this method.
220 $self->_process_lazy_build_option( $self->name, \%options )
221 if $self->can('_process_lazy_build_option');
223 $self->clone(%options);
227 my ( $self, %params ) = @_;
229 my $class = delete $params{metaclass} || ref $self;
231 my ( @init, @non_init );
233 foreach my $attr ( grep { $_->has_value($self) } Class::MOP::class_of($self)->get_all_attributes ) {
234 push @{ $attr->has_init_arg ? \@init : \@non_init }, $attr;
237 my %new_params = ( ( map { $_->init_arg => $_->get_value($self) } @init ), %params );
239 my $name = delete $new_params{name};
241 my $clone = $class->new($name, %new_params, __hack_no_process_options => 1 );
243 foreach my $attr ( @non_init ) {
244 $attr->set_value($clone, $attr->get_value($self));
250 sub _process_options {
251 my ( $class, $name, $options ) = @_;
253 $class->_process_is_option( $name, $options );
254 $class->_process_isa_option( $name, $options );
255 $class->_process_does_option( $name, $options );
256 $class->_process_coerce_option( $name, $options );
257 $class->_process_trigger_option( $name, $options );
258 $class->_process_auto_deref_option( $name, $options );
259 $class->_process_lazy_build_option( $name, $options );
260 $class->_process_lazy_option( $name, $options );
261 $class->_process_required_option( $name, $options );
264 sub _process_is_option {
265 my ( $class, $name, $options ) = @_;
267 return unless $options->{is};
269 ### -------------------------
270 ## is => ro, writer => _foo # turns into (reader => foo, writer => _foo) as before
271 ## is => rw, writer => _foo # turns into (reader => foo, writer => _foo)
272 ## is => rw, accessor => _foo # turns into (accessor => _foo)
273 ## is => ro, accessor => _foo # error, accesor is rw
274 ### -------------------------
276 if ( $options->{is} eq 'ro' ) {
278 "Cannot define an accessor name on a read-only attribute, accessors are read/write",
280 if exists $options->{accessor};
281 $options->{reader} ||= $name;
283 elsif ( $options->{is} eq 'rw' ) {
284 if ( $options->{writer} ) {
285 $options->{reader} ||= $name;
288 $options->{accessor} ||= $name;
291 elsif ( $options->{is} eq 'bare' ) {
293 # do nothing, but don't complain (later) about missing methods
296 $class->throw_error( "I do not understand this option (is => "
298 . ") on attribute ($name)", data => $options->{is} );
302 sub _process_isa_option {
303 my ( $class, $name, $options ) = @_;
305 return unless exists $options->{isa};
307 if ( exists $options->{does} ) {
308 if ( try { $options->{isa}->can('does') } ) {
309 ( $options->{isa}->does( $options->{does} ) )
310 || $class->throw_error(
311 "Cannot have an isa option and a does option if the isa does not do the does on attribute ($name)",
316 "Cannot have an isa option which cannot ->does() on attribute ($name)",
321 # allow for anon-subtypes here ...
322 if ( blessed( $options->{isa} )
323 && $options->{isa}->isa('Moose::Meta::TypeConstraint') ) {
324 $options->{type_constraint} = $options->{isa};
327 $options->{type_constraint}
328 = Moose::Util::TypeConstraints::find_or_create_isa_type_constraint(
333 sub _process_does_option {
334 my ( $class, $name, $options ) = @_;
336 return unless exists $options->{does} && ! exists $options->{isa};
338 # allow for anon-subtypes here ...
339 if ( blessed( $options->{does} )
340 && $options->{does}->isa('Moose::Meta::TypeConstraint') ) {
341 $options->{type_constraint} = $options->{does};
344 $options->{type_constraint}
345 = Moose::Util::TypeConstraints::find_or_create_does_type_constraint(
350 sub _process_coerce_option {
351 my ( $class, $name, $options ) = @_;
353 return unless $options->{coerce};
355 ( exists $options->{type_constraint} )
356 || $class->throw_error(
357 "You cannot have coercion without specifying a type constraint on attribute ($name)",
361 "You cannot have a weak reference to a coerced value on attribute ($name)",
363 if $options->{weak_ref};
365 unless ( $options->{type_constraint}->has_coercion ) {
366 my $type = $options->{type_constraint}->name;
368 Moose::Deprecated::deprecated(
369 feature => 'coerce without coercion',
371 "You cannot coerce an attribute ($name) unless its type ($type) has a coercion"
376 sub _process_trigger_option {
377 my ( $class, $name, $options ) = @_;
379 return unless exists $options->{trigger};
381 ( 'CODE' eq ref $options->{trigger} )
382 || $class->throw_error("Trigger must be a CODE ref on attribute ($name)", data => $options->{trigger});
385 sub _process_auto_deref_option {
386 my ( $class, $name, $options ) = @_;
388 return unless $options->{auto_deref};
390 ( exists $options->{type_constraint} )
391 || $class->throw_error(
392 "You cannot auto-dereference without specifying a type constraint on attribute ($name)",
395 ( $options->{type_constraint}->is_a_type_of('ArrayRef')
396 || $options->{type_constraint}->is_a_type_of('HashRef') )
397 || $class->throw_error(
398 "You cannot auto-dereference anything other than a ArrayRef or HashRef on attribute ($name)",
402 sub _process_lazy_build_option {
403 my ( $class, $name, $options ) = @_;
405 return unless $options->{lazy_build};
408 "You can not use lazy_build and default for the same attribute ($name)",
410 if exists $options->{default};
412 $options->{lazy} = 1;
413 $options->{builder} ||= "_build_${name}";
415 if ( $name =~ /^_/ ) {
416 $options->{clearer} ||= "_clear${name}";
417 $options->{predicate} ||= "_has${name}";
420 $options->{clearer} ||= "clear_${name}";
421 $options->{predicate} ||= "has_${name}";
425 sub _process_lazy_option {
426 my ( $class, $name, $options ) = @_;
428 return unless $options->{lazy};
430 ( exists $options->{default} || defined $options->{builder} )
431 || $class->throw_error(
432 "You cannot have a lazy attribute ($name) without specifying a default value for it",
436 sub _process_required_option {
437 my ( $class, $name, $options ) = @_;
442 ( !exists $options->{init_arg} || defined $options->{init_arg} )
443 || exists $options->{default}
444 || defined $options->{builder}
448 "You cannot have a required attribute ($name) without a default, builder, or an init_arg",
453 sub initialize_instance_slot {
454 my ($self, $meta_instance, $instance, $params) = @_;
455 my $init_arg = $self->init_arg();
456 # try to fetch the init arg from the %params ...
460 if ( defined($init_arg) and exists $params->{$init_arg}) {
461 $val = $params->{$init_arg};
465 # skip it if it's lazy
466 return if $self->is_lazy;
467 # and die if it's required and doesn't have a default value
468 $self->throw_error("Attribute (" . $self->name . ") is required", object => $instance, data => $params)
469 if $self->is_required && !$self->has_default && !$self->has_builder;
471 # if nothing was in the %params, we can use the
472 # attribute's default value (if it has one)
473 if ($self->has_default) {
474 $val = $self->default($instance);
477 elsif ($self->has_builder) {
478 $val = $self->_call_builder($instance);
483 return unless $value_is_set;
485 $val = $self->_coerce_and_verify( $val, $instance );
487 $self->set_initial_value($instance, $val);
489 if ( ref $val && $self->is_weak_ref ) {
490 $self->_weaken_value($instance);
495 my ( $self, $instance ) = @_;
497 my $builder = $self->builder();
499 return $instance->$builder()
500 if $instance->can( $self->builder );
502 $self->throw_error( blessed($instance)
503 . " does not support builder method '"
505 . "' for attribute '"
514 sub _make_initializer_writer_callback {
516 my ($meta_instance, $instance, $slot_name) = @_;
517 my $old_callback = $self->SUPER::_make_initializer_writer_callback(@_);
519 $old_callback->($self->_coerce_and_verify($_[0], $instance));
524 my ($self, $instance, @args) = @_;
525 my $value = $args[0];
527 my $attr_name = $self->name;
529 if ($self->is_required and not @args) {
530 $self->throw_error("Attribute ($attr_name) is required", object => $instance);
533 $value = $self->_coerce_and_verify( $value, $instance );
536 if ( $self->has_trigger && $self->has_value($instance) ) {
537 @old = $self->get_value($instance, 'for trigger');
540 $self->SUPER::set_value($instance, $value);
542 if ( ref $value && $self->is_weak_ref ) {
543 $self->_weaken_value($instance);
546 if ($self->has_trigger) {
547 $self->trigger->($instance, $value, @old);
551 sub _inline_set_value {
553 my ($instance, $value, $tc, $tc_obj, $for_constructor) = @_;
557 $tc ||= '$type_constraint';
558 $tc_obj ||= '$type_constraint_obj';
561 if ($self->_writer_value_needs_copy) {
562 push @code, $self->_inline_copy_value($value, $copy);
566 # constructors already handle required checks
567 push @code, $self->_inline_check_required
568 unless $for_constructor;
570 push @code, $self->_inline_tc_code($value, $tc, $tc_obj);
572 # constructors do triggers all at once at the end
573 push @code, $self->_inline_get_old_value_for_trigger($instance, $old)
574 unless $for_constructor;
577 $self->SUPER::_inline_set_value($instance, $value),
578 $self->_inline_weaken_value($instance, $value),
581 # constructors do triggers all at once at the end
582 push @code, $self->_inline_trigger($instance, $value, $old)
583 unless $for_constructor;
588 sub _writer_value_needs_copy {
590 return $self->should_coerce;
593 sub _inline_copy_value {
595 my ($value, $copy) = @_;
597 return 'my ' . $copy . ' = ' . $value . ';'
600 sub _inline_check_required {
603 return unless $self->is_required;
605 my $attr_name = quotemeta($self->name);
609 $self->_inline_throw_error(
610 '"Attribute (' . $attr_name . ') is required, so cannot '
611 . 'be set to undef"' # defined $_[1] is not good enough
617 sub _inline_tc_code {
620 $self->_inline_check_coercion(@_),
621 $self->_inline_check_constraint(@_),
625 sub _inline_check_coercion {
627 my ($value, $tc, $tc_obj) = @_;
629 return unless $self->should_coerce && $self->type_constraint->has_coercion;
631 return $value . ' = ' . $tc_obj . '->coerce(' . $value . ');';
634 sub _inline_check_constraint {
636 my ($value, $tc, $tc_obj) = @_;
638 return unless $self->has_type_constraint;
640 my $attr_name = quotemeta($self->name);
642 if ( $self->type_constraint->can_be_inlined ) {
644 'if (! (' . $self->type_constraint->_inline_check($value) . ')) {',
645 $self->_inline_throw_error(
646 '"Attribute (' . $attr_name . ') does not pass the type '
647 . 'constraint because: " . '
648 . $tc_obj . '->get_message(' . $value . ')',
656 'if (!' . $tc . '->(' . $value . ')) {',
657 $self->_inline_throw_error(
658 '"Attribute (' . $attr_name . ') does not pass the type '
659 . 'constraint because: " . '
660 . $tc_obj . '->get_message(' . $value . ')',
668 sub _inline_get_old_value_for_trigger {
670 my ($instance, $old) = @_;
672 return unless $self->has_trigger;
675 'my ' . $old . ' = ' . $self->_inline_instance_has($instance),
676 '? ' . $self->_inline_instance_get($instance),
681 sub _inline_weaken_value {
683 my ($instance, $value) = @_;
685 return unless $self->is_weak_ref;
687 my $mi = $self->associated_class->get_meta_instance;
689 $mi->inline_weaken_slot_value($instance, $self->name, $value),
690 'if ref ' . $value . ';',
694 sub _inline_trigger {
696 my ($instance, $value, $old) = @_;
698 return unless $self->has_trigger;
700 return '$attr->trigger->(' . $instance . ', ' . $value . ', ' . $old . ');';
704 my ( $self, $instance ) = @_;
706 my $meta_instance = Class::MOP::Class->initialize( blessed($instance) )
709 $meta_instance->weaken_slot_value( $instance, $self->name );
713 my ($self, $instance, $for_trigger) = @_;
715 if ($self->is_lazy) {
716 unless ($self->has_value($instance)) {
718 if ($self->has_default) {
719 $value = $self->default($instance);
720 } elsif ( $self->has_builder ) {
721 $value = $self->_call_builder($instance);
724 $value = $self->_coerce_and_verify( $value, $instance );
726 $self->set_initial_value($instance, $value);
730 if ( $self->should_auto_deref && ! $for_trigger ) {
732 my $type_constraint = $self->type_constraint;
734 if ($type_constraint->is_a_type_of('ArrayRef')) {
735 my $rv = $self->SUPER::get_value($instance);
736 return unless defined $rv;
737 return wantarray ? @{ $rv } : $rv;
739 elsif ($type_constraint->is_a_type_of('HashRef')) {
740 my $rv = $self->SUPER::get_value($instance);
741 return unless defined $rv;
742 return wantarray ? %{ $rv } : $rv;
745 $self->throw_error("Can not auto de-reference the type constraint '" . $type_constraint->name . "'", object => $instance, type_constraint => $type_constraint);
751 return $self->SUPER::get_value($instance);
755 sub _inline_get_value {
757 my ($instance, $tc, $tc_obj) = @_;
759 my $slot_access = $self->_inline_instance_get($instance);
760 $tc ||= '$type_constraint';
761 $tc_obj ||= '$type_constraint_obj';
764 $self->_inline_check_lazy($instance, $tc, $tc_obj),
765 $self->_inline_return_auto_deref($slot_access),
769 sub _inline_check_lazy {
771 my ($instance, $tc, $tc_obj) = @_;
773 return unless $self->is_lazy;
775 my $slot_exists = $self->_inline_instance_has($instance);
778 'if (!' . $slot_exists . ') {',
779 $self->_inline_init_from_default($instance, '$default', $tc, $tc_obj, 'lazy'),
784 sub _inline_init_from_default {
786 my ($instance, $default, $tc, $tc_obj, $for_lazy) = @_;
788 if (!($self->has_default || $self->has_builder)) {
790 'You cannot have a lazy attribute '
791 . '(' . $self->name . ') '
792 . 'without specifying a default value for it',
798 $self->_inline_generate_default($instance, $default),
799 # intentionally not using _inline_tc_code, since that can be overridden
800 # to do things like possibly only do member tc checks, which isn't
801 # appropriate for checking the result of a default
802 $self->has_type_constraint
803 ? ($self->_inline_check_coercion($default, $tc, $tc_obj, $for_lazy),
804 $self->_inline_check_constraint($default, $tc, $tc_obj, $for_lazy))
806 $self->_inline_init_slot($instance, $default),
810 sub _inline_generate_default {
812 my ($instance, $default) = @_;
814 if ($self->has_default) {
815 return 'my ' . $default . ' = $attr->default(' . $instance . ');';
817 elsif ($self->has_builder) {
819 'my ' . $default . ';',
820 'if (my $builder = ' . $instance . '->can($attr->builder)) {',
821 $default . ' = ' . $instance . '->$builder;',
824 'my $class = ref(' . $instance . ') || ' . $instance . ';',
825 'my $builder_name = $attr->builder;',
826 'my $attr_name = $attr->name;',
827 $self->_inline_throw_error(
828 '"$class does not support builder method '
829 . '\'$builder_name\' for attribute \'$attr_name\'"'
836 "Can't generate a default for " . $self->name
837 . " since no default or builder was specified"
842 sub _inline_init_slot {
844 my ($inv, $value) = @_;
846 if ($self->has_initializer) {
847 return '$attr->set_initial_value(' . $inv . ', ' . $value . ');';
850 return $self->_inline_instance_set($inv, $value) . ';';
854 sub _inline_return_auto_deref {
857 return 'return ' . $self->_auto_deref(@_) . ';';
862 my ($ref_value) = @_;
864 return $ref_value unless $self->should_auto_deref;
866 my $type_constraint = $self->type_constraint;
869 if ($type_constraint->is_a_type_of('ArrayRef')) {
872 elsif ($type_constraint->is_a_type_of('HashRef')) {
877 'Can not auto de-reference the type constraint \''
878 . $type_constraint->name
880 type_constraint => $type_constraint,
885 . '? ' . $sigil . '{ (' . $ref_value . ') || return } '
886 . ': (' . $ref_value . ')';
889 ## installing accessors
891 sub accessor_metaclass { 'Moose::Meta::Method::Accessor' }
893 sub install_accessors {
895 $self->SUPER::install_accessors(@_);
896 $self->install_delegation if $self->has_handles;
900 sub _check_associated_methods {
903 @{ $self->associated_methods }
904 || ($self->_is_metadata || '') eq 'bare'
907 'Attribute (' . $self->name . ') of class '
908 . $self->associated_class->name
909 . ' has no associated methods'
910 . ' (did you mean to provide an "is" argument?)'
916 sub _process_accessors {
918 my ($type, $accessor, $generate_as_inline_methods) = @_;
920 $accessor = ( keys %$accessor )[0] if ( ref($accessor) || '' ) eq 'HASH';
921 my $method = $self->associated_class->get_method($accessor);
924 && $method->isa('Class::MOP::Method::Accessor')
925 && $method->associated_attribute->name ne $self->name ) {
927 my $other_attr_name = $method->associated_attribute->name;
928 my $name = $self->name;
931 "You are overwriting an accessor ($accessor) for the $other_attr_name attribute"
932 . " with a new accessor method for the $name attribute" );
937 && !$method->isa('Class::MOP::Method::Accessor')
938 && ( !$self->definition_context
939 || $method->package_name eq $self->definition_context->{package} )
943 "You are overwriting a locally defined method ($accessor) with "
947 if ( !$self->associated_class->has_method($accessor)
948 && $self->associated_class->has_package_symbol( '&' . $accessor ) ) {
951 "You are overwriting a locally defined function ($accessor) with "
955 $self->SUPER::_process_accessors(@_);
958 sub remove_accessors {
960 $self->SUPER::remove_accessors(@_);
961 $self->remove_delegation if $self->has_handles;
965 sub install_delegation {
969 # Here we canonicalize the 'handles' option
970 # this will sort out any details and always
971 # return an hash of methods which we want
972 # to delagate to, see that method for details
973 my %handles = $self->_canonicalize_handles;
976 # install the delegation ...
977 my $associated_class = $self->associated_class;
978 foreach my $handle (keys %handles) {
979 my $method_to_call = $handles{$handle};
980 my $class_name = $associated_class->name;
981 my $name = "${class_name}::${handle}";
983 (!$associated_class->has_method($handle))
984 || $self->throw_error("You cannot overwrite a locally defined method ($handle) with a delegation", method_name => $handle);
987 # handles is not allowed to delegate
988 # any of these methods, as they will
989 # override the ones in your class, which
990 # is almost certainly not what you want.
992 # FIXME warn when $handle was explicitly specified, but not if the source is a regex or something
993 #cluck("Not delegating method '$handle' because it is a core method") and
994 next if $class_name->isa("Moose::Object") and $handle =~ /^BUILD|DEMOLISH$/ || Moose::Object->can($handle);
996 my $method = $self->_make_delegation_method($handle, $method_to_call);
998 $self->associated_class->add_method($method->name, $method);
999 $self->associate_method($method);
1003 sub remove_delegation {
1005 my %handles = $self->_canonicalize_handles;
1006 my $associated_class = $self->associated_class;
1007 foreach my $handle (keys %handles) {
1008 next unless any { $handle eq $_ }
1010 @{ $self->associated_methods };
1011 $self->associated_class->remove_method($handle);
1015 # private methods to help delegation ...
1017 sub _canonicalize_handles {
1019 my $handles = $self->handles;
1020 if (my $handle_type = ref($handles)) {
1021 if ($handle_type eq 'HASH') {
1024 elsif ($handle_type eq 'ARRAY') {
1025 return map { $_ => $_ } @{$handles};
1027 elsif ($handle_type eq 'Regexp') {
1028 ($self->has_type_constraint)
1029 || $self->throw_error("Cannot delegate methods based on a Regexp without a type constraint (isa)", data => $handles);
1030 return map { ($_ => $_) }
1031 grep { /$handles/ } $self->_get_delegate_method_list;
1033 elsif ($handle_type eq 'CODE') {
1034 return $handles->($self, $self->_find_delegate_metaclass);
1036 elsif (blessed($handles) && $handles->isa('Moose::Meta::TypeConstraint::DuckType')) {
1037 return map { $_ => $_ } @{ $handles->methods };
1039 elsif (blessed($handles) && $handles->isa('Moose::Meta::TypeConstraint::Role')) {
1040 $handles = $handles->role;
1043 $self->throw_error("Unable to canonicalize the 'handles' option with $handles", data => $handles);
1047 Class::MOP::load_class($handles);
1048 my $role_meta = Class::MOP::class_of($handles);
1050 (blessed $role_meta && $role_meta->isa('Moose::Meta::Role'))
1051 || $self->throw_error("Unable to canonicalize the 'handles' option with $handles because its metaclass is not a Moose::Meta::Role", data => $handles);
1053 return map { $_ => $_ }
1055 grep { !$_->isa('Class::MOP::Method::Meta') } (
1056 $role_meta->_get_local_methods,
1057 $role_meta->get_required_method_list,
1061 sub _get_delegate_method_list {
1063 my $meta = $self->_find_delegate_metaclass;
1064 if ($meta->isa('Class::MOP::Class')) {
1065 return map { $_->name } # NOTE: !never! delegate &meta
1066 grep { $_->package_name ne 'Moose::Object' && !$_->isa('Class::MOP::Method::Meta') }
1067 $meta->get_all_methods;
1069 elsif ($meta->isa('Moose::Meta::Role')) {
1070 return $meta->get_method_list;
1073 $self->throw_error("Unable to recognize the delegate metaclass '$meta'", data => $meta);
1077 sub _find_delegate_metaclass {
1079 if (my $class = $self->_isa_metadata) {
1080 unless ( Class::MOP::is_class_loaded($class) ) {
1083 'The %s attribute is trying to delegate to a class which has not been loaded - %s',
1088 # we might be dealing with a non-Moose class,
1089 # and need to make our own metaclass. if there's
1090 # already a metaclass, it will be returned
1091 return Class::MOP::Class->initialize($class);
1093 elsif (my $role = $self->_does_metadata) {
1094 unless ( Class::MOP::is_class_loaded($class) ) {
1097 'The %s attribute is trying to delegate to a role which has not been loaded - %s',
1103 return Class::MOP::class_of($role);
1106 $self->throw_error("Cannot find delegate metaclass for attribute " . $self->name);
1110 sub delegation_metaclass { 'Moose::Meta::Method::Delegation' }
1112 sub _make_delegation_method {
1113 my ( $self, $handle_name, $method_to_call ) = @_;
1115 my @curried_arguments;
1117 ($method_to_call, @curried_arguments) = @$method_to_call
1118 if 'ARRAY' eq ref($method_to_call);
1120 return $self->delegation_metaclass->new(
1121 name => $handle_name,
1122 package_name => $self->associated_class->name,
1124 delegate_to_method => $method_to_call,
1125 curried_arguments => \@curried_arguments,
1129 sub _coerce_and_verify {
1132 my $instance = shift;
1134 return $val unless $self->has_type_constraint;
1136 $val = $self->type_constraint->coerce($val)
1137 if $self->should_coerce && $self->type_constraint->has_coercion;
1139 $self->verify_against_type_constraint($val, instance => $instance);
1144 sub verify_against_type_constraint {
1148 return 1 if !$self->has_type_constraint;
1150 my $type_constraint = $self->type_constraint;
1152 $type_constraint->check($val)
1153 || $self->throw_error("Attribute ("
1155 . ") does not pass the type constraint because: "
1156 . $type_constraint->get_message($val), data => $val, @_);
1159 package Moose::Meta::Attribute::Custom::Moose;
1160 sub register_implementation { 'Moose::Meta::Attribute' }
1164 # ABSTRACT: The Moose attribute metaclass
1172 This class is a subclass of L<Class::MOP::Attribute> that provides
1173 additional Moose-specific functionality.
1175 To really understand this class, you will need to start with the
1176 L<Class::MOP::Attribute> documentation. This class can be understood
1177 as a set of additional features on top of the basic feature provided
1178 by that parent class.
1182 C<Moose::Meta::Attribute> is a subclass of L<Class::MOP::Attribute>.
1186 Many of the documented below override methods in
1187 L<Class::MOP::Attribute> and add Moose specific features.
1193 =item B<< Moose::Meta::Attribute->new(%options) >>
1195 This method overrides the L<Class::MOP::Attribute> constructor.
1197 Many of the options below are described in more detail in the
1198 L<Moose::Manual::Attributes> document.
1200 It adds the following options to the constructor:
1204 =item * is => 'ro', 'rw', 'bare'
1206 This provides a shorthand for specifying the C<reader>, C<writer>, or
1207 C<accessor> names. If the attribute is read-only ('ro') then it will
1208 have a C<reader> method with the same attribute as the name.
1210 If it is read-write ('rw') then it will have an C<accessor> method
1211 with the same name. If you provide an explicit C<writer> for a
1212 read-write attribute, then you will have a C<reader> with the same
1213 name as the attribute, and a C<writer> with the name you provided.
1215 Use 'bare' when you are deliberately not installing any methods
1216 (accessor, reader, etc.) associated with this attribute; otherwise,
1217 Moose will issue a deprecation warning when this attribute is added to a
1220 =item * isa => $type
1222 This option accepts a type. The type can be a string, which should be
1223 a type name. If the type name is unknown, it is assumed to be a class
1226 This option can also accept a L<Moose::Meta::TypeConstraint> object.
1228 If you I<also> provide a C<does> option, then your C<isa> option must
1229 be a class name, and that class must do the role specified with
1232 =item * does => $role
1234 This is short-hand for saying that the attribute's type must be an
1235 object which does the named role.
1237 =item * coerce => $bool
1239 This option is only valid for objects with a type constraint
1240 (C<isa>) that defined a coercion. If this is true, then coercions will be applied whenever
1241 this attribute is set.
1243 You can make both this and the C<weak_ref> option true.
1245 =item * trigger => $sub
1247 This option accepts a subroutine reference, which will be called after
1248 the attribute is set.
1250 =item * required => $bool
1252 An attribute which is required must be provided to the constructor. An
1253 attribute which is required can also have a C<default> or C<builder>,
1254 which will satisfy its required-ness.
1256 A required attribute must have a C<default>, C<builder> or a
1257 non-C<undef> C<init_arg>
1259 =item * lazy => $bool
1261 A lazy attribute must have a C<default> or C<builder>. When an
1262 attribute is lazy, the default value will not be calculated until the
1265 =item * weak_ref => $bool
1267 If this is true, the attribute's value will be stored as a weak
1270 =item * auto_deref => $bool
1272 If this is true, then the reader will dereference the value when it is
1273 called. The attribute must have a type constraint which defines the
1274 attribute as an array or hash reference.
1276 =item * lazy_build => $bool
1278 Setting this to true makes the attribute lazy and provides a number of
1286 is equivalent to this:
1291 builder => '_build_size',
1292 clearer => 'clear_size',
1293 predicate => 'has_size',
1297 If your attribute name starts with an underscore (C<_>), then the clearer
1298 and predicate will as well:
1310 builder => '_build__size',
1311 clearer => '_clear_size',
1312 predicate => '_has_size',
1315 Note the doubled underscore in the builder name. Internally, Moose
1316 simply prepends the attribute name with "_build_" to come up with the
1319 =item * documentation
1321 An arbitrary string that can be retrieved later by calling C<<
1322 $attr->documentation >>.
1326 =item B<< $attr->clone(%options) >>
1328 This creates a new attribute based on attribute being cloned. You must
1329 supply a C<name> option to provide a new name for the attribute.
1331 The C<%options> can only specify options handled by
1332 L<Class::MOP::Attribute>.
1336 =head2 Value management
1340 =item B<< $attr->initialize_instance_slot($meta_instance, $instance, $params) >>
1342 This method is used internally to initialize the attribute's slot in
1343 the object C<$instance>.
1345 This overrides the L<Class::MOP::Attribute> method to handle lazy
1346 attributes, weak references, and type constraints.
1352 eval { $point->meta->get_attribute('x')->set_value($point, 'forty-two') };
1357 I<Attribute (x) does not pass the type constraint (Int) with 'forty-two'>
1359 Before setting the value, a check is made on the type constraint of
1360 the attribute, if it has one, to see if the value passes it. If the
1361 value fails to pass, the set operation dies with a L</throw_error>.
1363 Any coercion to convert values is done before checking the type constraint.
1365 To check a value against a type constraint before setting it, fetch the
1366 attribute instance using L<Class::MOP::Class/find_attribute_by_name>,
1367 fetch the type_constraint from the attribute using L<Moose::Meta::Attribute/type_constraint>
1368 and call L<Moose::Meta::TypeConstraint/check>. See L<Moose::Cookbook::Basics::Recipe4>
1373 =head2 Attribute Accessor generation
1377 =item B<< $attr->install_accessors >>
1379 This method overrides the parent to also install delegation methods.
1381 If, after installing all methods, the attribute object has no associated
1382 methods, it throws an error unless C<< is => 'bare' >> was passed to the
1383 attribute constructor. (Trying to add an attribute that has no associated
1384 methods is almost always an error.)
1386 =item B<< $attr->remove_accessors >>
1388 This method overrides the parent to also remove delegation methods.
1390 =item B<< $attr->inline_set($instance_var, $value_var) >>
1392 This method return a code snippet suitable for inlining the relevant
1393 operation. It expect strings containing variable names to be used in the
1394 inlining, like C<'$self'> or C<'$_[1]'>.
1396 =item B<< $attr->install_delegation >>
1398 This method adds its delegation methods to the attribute's associated
1399 class, if it has any to add.
1401 =item B<< $attr->remove_delegation >>
1403 This method remove its delegation methods from the attribute's
1406 =item B<< $attr->accessor_metaclass >>
1408 Returns the accessor metaclass name, which defaults to
1409 L<Moose::Meta::Method::Accessor>.
1411 =item B<< $attr->delegation_metaclass >>
1413 Returns the delegation metaclass name, which defaults to
1414 L<Moose::Meta::Method::Delegation>.
1418 =head2 Additional Moose features
1420 These methods are not found in the superclass. They support features
1425 =item B<< $attr->does($role) >>
1427 This indicates whether the I<attribute itself> does the given
1428 role. The role can be given as a full class name, or as a resolvable
1431 Note that this checks the attribute itself, not its type constraint,
1432 so it is checking the attribute's metaclass and any traits applied to
1435 =item B<< Moose::Meta::Class->interpolate_class_and_new($name, %options) >>
1437 This is an alternate constructor that handles the C<metaclass> and
1440 Effectively, this method is a factory that finds or creates the
1441 appropriate class for the given C<metaclass> and/or C<traits>.
1443 Once it has the appropriate class, it will call C<< $class->new($name,
1444 %options) >> on that class.
1446 =item B<< $attr->clone_and_inherit_options(%options) >>
1448 This method supports the C<has '+foo'> feature. It does various bits
1449 of processing on the supplied C<%options> before ultimately calling
1450 the C<clone> method.
1452 One of its main tasks is to make sure that the C<%options> provided
1453 does not include the options returned by the
1454 C<illegal_options_for_inheritance> method.
1456 =item B<< $attr->illegal_options_for_inheritance >>
1458 This returns a blacklist of options that can not be overridden in a
1459 subclass's attribute definition.
1461 This exists to allow a custom metaclass to change or add to the list
1462 of options which can not be changed.
1464 =item B<< $attr->type_constraint >>
1466 Returns the L<Moose::Meta::TypeConstraint> object for this attribute,
1469 =item B<< $attr->has_type_constraint >>
1471 Returns true if this attribute has a type constraint.
1473 =item B<< $attr->verify_against_type_constraint($value) >>
1475 Given a value, this method returns true if the value is valid for the
1476 attribute's type constraint. If the value is not valid, it throws an
1479 =item B<< $attr->handles >>
1481 This returns the value of the C<handles> option passed to the
1484 =item B<< $attr->has_handles >>
1486 Returns true if this attribute performs delegation.
1488 =item B<< $attr->is_weak_ref >>
1490 Returns true if this attribute stores its value as a weak reference.
1492 =item B<< $attr->is_required >>
1494 Returns true if this attribute is required to have a value.
1496 =item B<< $attr->is_lazy >>
1498 Returns true if this attribute is lazy.
1500 =item B<< $attr->is_lazy_build >>
1502 Returns true if the C<lazy_build> option was true when passed to the
1505 =item B<< $attr->should_coerce >>
1507 Returns true if the C<coerce> option passed to the constructor was
1510 =item B<< $attr->should_auto_deref >>
1512 Returns true if the C<auto_deref> option passed to the constructor was
1515 =item B<< $attr->trigger >>
1517 This is the subroutine reference that was in the C<trigger> option
1518 passed to the constructor, if any.
1520 =item B<< $attr->has_trigger >>
1522 Returns true if this attribute has a trigger set.
1524 =item B<< $attr->documentation >>
1526 Returns the value that was in the C<documentation> option passed to
1527 the constructor, if any.
1529 =item B<< $attr->has_documentation >>
1531 Returns true if this attribute has any documentation.
1533 =item B<< $attr->applied_traits >>
1535 This returns an array reference of all the traits which were applied
1536 to this attribute. If none were applied, this returns C<undef>.
1538 =item B<< $attr->has_applied_traits >>
1540 Returns true if this attribute has any traits applied.
1546 See L<Moose/BUGS> for details on reporting bugs.