2 package Moose::Meta::Attribute;
8 use Scalar::Util 'blessed', 'weaken';
9 use List::MoreUtils 'any';
13 our $VERSION = '1.19';
14 our $AUTHORITY = 'cpan:STEVAN';
16 use Moose::Deprecated;
17 use Moose::Meta::Method::Accessor;
18 use Moose::Meta::Method::Delegation;
20 use Moose::Util::TypeConstraints ();
21 use Class::MOP::MiniTrait;
23 use base 'Class::MOP::Attribute', 'Moose::Meta::Mixin::AttributeCore';
25 Class::MOP::MiniTrait::apply(__PACKAGE__, 'Moose::Meta::Object::Trait');
27 __PACKAGE__->meta->add_attribute('traits' => (
28 reader => 'applied_traits',
29 predicate => 'has_applied_traits',
32 # we need to have a ->does method in here to
33 # more easily support traits, and the introspection
34 # of those traits. We extend the does check to look
35 # for metatrait aliases.
37 my ($self, $role_name) = @_;
39 Moose::Util::resolve_metatrait_alias(Attribute => $role_name)
41 return 0 if !defined($name); # failed to load class
42 return $self->Moose::Object::does($name);
47 my $class = ( ref $self && $self->associated_class ) || "Moose::Meta::Class";
48 unshift @_, "message" if @_ % 2 == 1;
49 unshift @_, attr => $self if ref $self;
51 my $handler = $class->can("throw_error"); # to avoid incrementing depth by 1
55 sub _inline_throw_error {
56 my ( $self, $msg, $args ) = @_;
57 "\$meta->throw_error($msg" . ($args ? ", $args" : "") . ")"; # FIXME makes deparsing *REALLY* hard
61 my ($class, $name, %options) = @_;
62 $class->_process_options($name, \%options) unless $options{__hack_no_process_options}; # used from clone()... YECHKKK FIXME ICKY YUCK GROSS
64 delete $options{__hack_no_process_options};
69 map { $_->init_arg() }
70 $class->meta()->get_all_attributes()
73 my @bad = sort grep { ! $attrs{$_} } keys %options;
77 Carp::cluck "Found unknown argument(s) passed to '$name' attribute constructor in '$class': @bad";
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 ) : $class );
144 # method-generating options shouldn't be overridden
145 sub illegal_options_for_inheritance {
146 qw(reader writer accessor clearer predicate)
150 # This method *must* be able to handle
151 # Class::MOP::Attribute instances as
152 # well. Yes, I know that is wrong, but
153 # apparently we didn't realize it was
154 # doing that and now we have some code
155 # which is dependent on it. The real
156 # solution of course is to push this
157 # feature back up into Class::MOP::Attribute
158 # but I not right now, I am too lazy.
159 # However if you are reading this and
160 # looking for something to do,.. please
163 sub clone_and_inherit_options {
164 my ($self, %options) = @_;
167 # we may want to extends a Class::MOP::Attribute
168 # in which case we need to be able to use the
169 # core set of legal options that have always
170 # been here. But we allows Moose::Meta::Attribute
171 # instances to changes them.
173 my @illegal_options = $self->can('illegal_options_for_inheritance')
174 ? $self->illegal_options_for_inheritance
177 my @found_illegal_options = grep { exists $options{$_} && exists $self->{$_} ? $_ : undef } @illegal_options;
178 (scalar @found_illegal_options == 0)
179 || $self->throw_error("Illegal inherited options => (" . (join ', ' => @found_illegal_options) . ")", data => \%options);
183 if (blessed($options{isa}) && $options{isa}->isa('Moose::Meta::TypeConstraint')) {
184 $type_constraint = $options{isa};
187 $type_constraint = Moose::Util::TypeConstraints::find_or_create_isa_type_constraint($options{isa});
188 (defined $type_constraint)
189 || $self->throw_error("Could not find the type constraint '" . $options{isa} . "'", data => $options{isa});
192 $options{type_constraint} = $type_constraint;
195 if ($options{does}) {
197 if (blessed($options{does}) && $options{does}->isa('Moose::Meta::TypeConstraint')) {
198 $type_constraint = $options{does};
201 $type_constraint = Moose::Util::TypeConstraints::find_or_create_does_type_constraint($options{does});
202 (defined $type_constraint)
203 || $self->throw_error("Could not find the type constraint '" . $options{does} . "'", data => $options{does});
206 $options{type_constraint} = $type_constraint;
210 # this doesn't apply to Class::MOP::Attributes,
211 # so we can ignore it for them.
213 if ($self->can('interpolate_class')) {
214 ( $options{metaclass}, my @traits ) = $self->interpolate_class(\%options);
217 my @all_traits = grep { $seen{$_}++ } @{ $self->applied_traits || [] }, @traits;
218 $options{traits} = \@all_traits if @all_traits;
221 # This method can be called on a CMOP::Attribute object, so we need to
222 # make sure we can call this method.
223 $self->_process_lazy_build_option( $self->name, \%options )
224 if $self->can('_process_lazy_build_option');
226 $self->clone(%options);
230 my ( $self, %params ) = @_;
232 my $class = delete $params{metaclass} || ref $self;
234 my ( @init, @non_init );
236 foreach my $attr ( grep { $_->has_value($self) } Class::MOP::class_of($self)->get_all_attributes ) {
237 push @{ $attr->has_init_arg ? \@init : \@non_init }, $attr;
240 my %new_params = ( ( map { $_->init_arg => $_->get_value($self) } @init ), %params );
242 my $name = delete $new_params{name};
244 my $clone = $class->new($name, %new_params, __hack_no_process_options => 1 );
246 foreach my $attr ( @non_init ) {
247 $attr->set_value($clone, $attr->get_value($self));
253 sub _process_options {
254 my ( $class, $name, $options ) = @_;
256 $class->_process_is_option( $name, $options );
257 $class->_process_isa_option( $name, $options );
258 $class->_process_does_option( $name, $options );
259 $class->_process_coerce_option( $name, $options );
260 $class->_process_trigger_option( $name, $options );
261 $class->_process_auto_deref_option( $name, $options );
262 $class->_process_lazy_build_option( $name, $options );
263 $class->_process_lazy_option( $name, $options );
264 $class->_process_required_option( $name, $options );
267 sub _process_is_option {
268 my ( $class, $name, $options ) = @_;
270 return unless $options->{is};
272 ### -------------------------
273 ## is => ro, writer => _foo # turns into (reader => foo, writer => _foo) as before
274 ## is => rw, writer => _foo # turns into (reader => foo, writer => _foo)
275 ## is => rw, accessor => _foo # turns into (accessor => _foo)
276 ## is => ro, accessor => _foo # error, accesor is rw
277 ### -------------------------
279 if ( $options->{is} eq 'ro' ) {
281 "Cannot define an accessor name on a read-only attribute, accessors are read/write",
283 if exists $options->{accessor};
284 $options->{reader} ||= $name;
286 elsif ( $options->{is} eq 'rw' ) {
287 if ( $options->{writer} ) {
288 $options->{reader} ||= $name;
291 $options->{accessor} ||= $name;
294 elsif ( $options->{is} eq 'bare' ) {
296 # do nothing, but don't complain (later) about missing methods
299 $class->throw_error( "I do not understand this option (is => "
301 . ") on attribute ($name)", data => $options->{is} );
305 sub _process_isa_option {
306 my ( $class, $name, $options ) = @_;
308 return unless exists $options->{isa};
310 if ( exists $options->{does} ) {
311 if ( try { $options->{isa}->can('does') } ) {
312 ( $options->{isa}->does( $options->{does} ) )
313 || $class->throw_error(
314 "Cannot have an isa option and a does option if the isa does not do the does on attribute ($name)",
319 "Cannot have an isa option which cannot ->does() on attribute ($name)",
324 # allow for anon-subtypes here ...
325 if ( blessed( $options->{isa} )
326 && $options->{isa}->isa('Moose::Meta::TypeConstraint') ) {
327 $options->{type_constraint} = $options->{isa};
330 $options->{type_constraint}
331 = Moose::Util::TypeConstraints::find_or_create_isa_type_constraint(
336 sub _process_does_option {
337 my ( $class, $name, $options ) = @_;
339 return unless exists $options->{does} && ! exists $options->{isa};
341 # allow for anon-subtypes here ...
342 if ( blessed( $options->{does} )
343 && $options->{does}->isa('Moose::Meta::TypeConstraint') ) {
344 $options->{type_constraint} = $options->{does};
347 $options->{type_constraint}
348 = Moose::Util::TypeConstraints::find_or_create_does_type_constraint(
353 sub _process_coerce_option {
354 my ( $class, $name, $options ) = @_;
356 return unless $options->{coerce};
358 ( exists $options->{type_constraint} )
359 || $class->throw_error(
360 "You cannot have coercion without specifying a type constraint on attribute ($name)",
364 "You cannot have a weak reference to a coerced value on attribute ($name)",
366 if $options->{weak_ref};
368 unless ( $options->{type_constraint}->has_coercion ) {
369 my $type = $options->{type_constraint}->name;
371 Moose::Deprecated::deprecated(
372 feature => 'coerce without coercion',
374 "You cannot coerce an attribute ($name) unless its type ($type) has a coercion"
379 sub _process_trigger_option {
380 my ( $class, $name, $options ) = @_;
382 return unless exists $options->{trigger};
384 ( 'CODE' eq ref $options->{trigger} )
385 || $class->throw_error("Trigger must be a CODE ref on attribute ($name)", data => $options->{trigger});
388 sub _process_auto_deref_option {
389 my ( $class, $name, $options ) = @_;
391 return unless $options->{auto_deref};
393 ( exists $options->{type_constraint} )
394 || $class->throw_error(
395 "You cannot auto-dereference without specifying a type constraint on attribute ($name)",
398 ( $options->{type_constraint}->is_a_type_of('ArrayRef')
399 || $options->{type_constraint}->is_a_type_of('HashRef') )
400 || $class->throw_error(
401 "You cannot auto-dereference anything other than a ArrayRef or HashRef on attribute ($name)",
405 sub _process_lazy_build_option {
406 my ( $class, $name, $options ) = @_;
408 return unless $options->{lazy_build};
411 "You can not use lazy_build and default for the same attribute ($name)",
413 if exists $options->{default};
415 $options->{lazy} = 1;
416 $options->{builder} ||= "_build_${name}";
418 if ( $name =~ /^_/ ) {
419 $options->{clearer} ||= "_clear${name}";
420 $options->{predicate} ||= "_has${name}";
423 $options->{clearer} ||= "clear_${name}";
424 $options->{predicate} ||= "has_${name}";
428 sub _process_lazy_option {
429 my ( $class, $name, $options ) = @_;
431 return unless $options->{lazy};
433 ( exists $options->{default} || defined $options->{builder} )
434 || $class->throw_error(
435 "You cannot have a lazy attribute ($name) without specifying a default value for it",
439 sub _process_required_option {
440 my ( $class, $name, $options ) = @_;
445 ( !exists $options->{init_arg} || defined $options->{init_arg} )
446 || exists $options->{default}
447 || defined $options->{builder}
451 "You cannot have a required attribute ($name) without a default, builder, or an init_arg",
456 sub initialize_instance_slot {
457 my ($self, $meta_instance, $instance, $params) = @_;
458 my $init_arg = $self->init_arg();
459 # try to fetch the init arg from the %params ...
463 if ( defined($init_arg) and exists $params->{$init_arg}) {
464 $val = $params->{$init_arg};
468 # skip it if it's lazy
469 return if $self->is_lazy;
470 # and die if it's required and doesn't have a default value
471 $self->throw_error("Attribute (" . $self->name . ") is required", object => $instance, data => $params)
472 if $self->is_required && !$self->has_default && !$self->has_builder;
474 # if nothing was in the %params, we can use the
475 # attribute's default value (if it has one)
476 if ($self->has_default) {
477 $val = $self->default($instance);
480 elsif ($self->has_builder) {
481 $val = $self->_call_builder($instance);
486 return unless $value_is_set;
488 $val = $self->_coerce_and_verify( $val, $instance );
490 $self->set_initial_value($instance, $val);
492 if ( ref $val && $self->is_weak_ref ) {
493 $self->_weaken_value($instance);
498 my ( $self, $instance ) = @_;
500 my $builder = $self->builder();
502 return $instance->$builder()
503 if $instance->can( $self->builder );
505 $self->throw_error( blessed($instance)
506 . " does not support builder method '"
508 . "' for attribute '"
517 sub _make_initializer_writer_callback {
519 my ($meta_instance, $instance, $slot_name) = @_;
520 my $old_callback = $self->SUPER::_make_initializer_writer_callback(@_);
522 $old_callback->($self->_coerce_and_verify($_[0], $instance));
527 my ($self, $instance, @args) = @_;
528 my $value = $args[0];
530 my $attr_name = $self->name;
532 if ($self->is_required and not @args) {
533 $self->throw_error("Attribute ($attr_name) is required", object => $instance);
536 $value = $self->_coerce_and_verify( $value, $instance );
539 if ( $self->has_trigger && $self->has_value($instance) ) {
540 @old = $self->get_value($instance, 'for trigger');
543 $self->SUPER::set_value($instance, $value);
545 if ( ref $value && $self->is_weak_ref ) {
546 $self->_weaken_value($instance);
549 if ($self->has_trigger) {
550 $self->trigger->($instance, $value, @old);
554 sub _inline_set_value {
556 my ($instance, $value) = @_;
562 if ($self->_writer_value_needs_copy) {
563 push @code, $self->_inline_copy_value($value, $copy);
568 $self->_inline_check_required,
569 $self->_inline_tc_code($value),
570 $self->_inline_get_old_value_for_trigger($instance, $old),
571 $self->SUPER::_inline_set_value($instance, $value),
572 $self->_inline_weaken_value($instance, $value),
573 $self->_inline_trigger($instance, $value, $old),
579 sub _writer_value_needs_copy {
581 return $self->should_coerce;
584 sub _inline_copy_value {
586 my ($value, $copy) = @_;
588 return 'my ' . $copy . ' = ' . $value . ';'
591 sub _inline_check_required {
594 return unless $self->is_required;
596 my $attr_name = quotemeta($self->name);
600 $self->_inline_throw_error(
601 '"Attribute (' . $attr_name . ') is required, so cannot '
602 . 'be set to undef"' # defined $_[1] is not good enough
608 sub _inline_tc_code {
611 $self->_inline_check_coercion(@_),
612 $self->_inline_check_constraint(@_),
616 sub _inline_check_coercion {
620 return unless $self->should_coerce && $self->type_constraint->has_coercion;
622 return $value . ' = $type_constraint_obj->coerce(' . $value . ');';
625 sub _inline_check_constraint {
629 return unless $self->has_type_constraint;
631 my $attr_name = quotemeta($self->name);
634 'if (!$type_constraint->(' . $value . ')) {',
635 $self->_inline_throw_error(
636 '"Attribute (' . $attr_name . ') does not pass the type '
637 . 'constraint because: " . '
638 . '$type_constraint_obj->get_message(' . $value . ')',
645 sub _inline_get_old_value_for_trigger {
647 my ($instance, $old) = @_;
649 return unless $self->has_trigger;
652 'my ' . $old . ' = ' . $self->_inline_instance_has($instance),
653 '? ' . $self->_inline_instance_get($instance),
658 sub _inline_weaken_value {
660 my ($instance, $value) = @_;
662 return unless $self->is_weak_ref;
664 my $mi = $self->associated_class->get_meta_instance;
666 $mi->inline_weaken_slot_value($instance, $self->name, $value),
667 'if ref ' . $value . ';',
671 sub _inline_trigger {
673 my ($instance, $value, $old) = @_;
675 return unless $self->has_trigger;
677 return '$attr->trigger->(' . $instance . ', ' . $value . ', ' . $old . ');';
681 my ( $self, $instance ) = @_;
683 my $meta_instance = Class::MOP::Class->initialize( blessed($instance) )
686 $meta_instance->weaken_slot_value( $instance, $self->name );
690 my ($self, $instance, $for_trigger) = @_;
692 if ($self->is_lazy) {
693 unless ($self->has_value($instance)) {
695 if ($self->has_default) {
696 $value = $self->default($instance);
697 } elsif ( $self->has_builder ) {
698 $value = $self->_call_builder($instance);
701 $value = $self->_coerce_and_verify( $value, $instance );
703 $self->set_initial_value($instance, $value);
707 if ( $self->should_auto_deref && ! $for_trigger ) {
709 my $type_constraint = $self->type_constraint;
711 if ($type_constraint->is_a_type_of('ArrayRef')) {
712 my $rv = $self->SUPER::get_value($instance);
713 return unless defined $rv;
714 return wantarray ? @{ $rv } : $rv;
716 elsif ($type_constraint->is_a_type_of('HashRef')) {
717 my $rv = $self->SUPER::get_value($instance);
718 return unless defined $rv;
719 return wantarray ? %{ $rv } : $rv;
722 $self->throw_error("Can not auto de-reference the type constraint '" . $type_constraint->name . "'", object => $instance, type_constraint => $type_constraint);
728 return $self->SUPER::get_value($instance);
732 sub _inline_get_value {
736 my $slot_access = $self->_inline_instance_get($instance);
739 $self->_inline_check_lazy($instance),
740 $self->_inline_return_auto_deref($slot_access),
744 sub _inline_check_lazy {
746 my ($instance, $default) = @_;
748 return unless $self->is_lazy;
750 my $slot_exists = $self->_inline_instance_has($instance);
753 'if (!' . $slot_exists . ') {',
754 $self->_inline_init_from_default($instance, '$default', 'lazy'),
759 sub _inline_init_from_default {
761 my ($instance, $default, $for_lazy) = @_;
763 if (!($self->has_default || $self->has_builder)) {
765 'You cannot have a lazy attribute '
766 . '(' . $self->name . ') '
767 . 'without specifying a default value for it',
773 $self->_inline_generate_default($instance, $default),
774 # intentionally not using _inline_tc_code, since that can be overridden
775 # to do things like possibly only do member tc checks, which isn't
776 # appropriate for checking the result of a default
777 $self->has_type_constraint
778 ? ($self->_inline_check_coercion($default, $for_lazy),
779 $self->_inline_check_constraint($default, $for_lazy))
781 $self->_inline_init_slot($instance, $default),
785 sub _inline_generate_default {
787 my ($instance, $default) = @_;
789 if ($self->has_default) {
790 return 'my ' . $default . ' = $attr->default(' . $instance . ');';
792 elsif ($self->has_builder) {
794 'my ' . $default . ';',
795 'if (my $builder = ' . $instance . '->can($attr->builder)) {',
796 $default . ' = ' . $instance . '->$builder;',
799 'my $class = ref(' . $instance . ') || ' . $instance . ';',
800 'my $builder_name = $attr->builder;',
801 'my $attr_name = $attr->name;',
802 $self->_inline_throw_error(
803 '"$class does not support builder method '
804 . '\'$builder_name\' for attribute \'$attr_name\'"'
811 "Can't generate a default for " . $self->name
812 . " since no default or builder was specified"
817 sub _inline_init_slot {
819 my ($inv, $value) = @_;
821 if ($self->has_initializer) {
822 return '$attr->set_initial_value(' . $inv . ', ' . $value . ');';
825 return $self->_inline_instance_set($inv, $value) . ';';
829 sub _inline_return_auto_deref {
832 return 'return ' . $self->_auto_deref(@_) . ';';
837 my ($ref_value) = @_;
839 return $ref_value unless $self->should_auto_deref;
841 my $type_constraint = $self->type_constraint;
844 if ($type_constraint->is_a_type_of('ArrayRef')) {
847 elsif ($type_constraint->is_a_type_of('HashRef')) {
852 'Can not auto de-reference the type constraint \''
853 . $type_constraint->name
855 type_constraint => $type_constraint,
860 . '? ' . $sigil . '{ (' . $ref_value . ') || return } '
861 . ': (' . $ref_value . ')';
864 ## installing accessors
866 sub accessor_metaclass { 'Moose::Meta::Method::Accessor' }
868 sub install_accessors {
870 $self->SUPER::install_accessors(@_);
871 $self->install_delegation if $self->has_handles;
875 sub _check_associated_methods {
878 @{ $self->associated_methods }
879 || ($self->_is_metadata || '') eq 'bare'
882 'Attribute (' . $self->name . ') of class '
883 . $self->associated_class->name
884 . ' has no associated methods'
885 . ' (did you mean to provide an "is" argument?)'
891 sub _process_accessors {
893 my ($type, $accessor, $generate_as_inline_methods) = @_;
895 $accessor = ( keys %$accessor )[0] if ( ref($accessor) || '' ) eq 'HASH';
896 my $method = $self->associated_class->get_method($accessor);
899 && $method->isa('Class::MOP::Method::Accessor')
900 && $method->associated_attribute->name ne $self->name ) {
902 my $other_attr_name = $method->associated_attribute->name;
903 my $name = $self->name;
906 "You are overwriting an accessor ($accessor) for the $other_attr_name attribute"
907 . " with a new accessor method for the $name attribute" );
912 && !$method->isa('Class::MOP::Method::Accessor')
913 && ( !$self->definition_context
914 || $method->package_name eq $self->definition_context->{package} )
918 "You are overwriting a locally defined method ($accessor) with "
922 if ( !$self->associated_class->has_method($accessor)
923 && $self->associated_class->has_package_symbol( '&' . $accessor ) ) {
926 "You are overwriting a locally defined function ($accessor) with "
930 $self->SUPER::_process_accessors(@_);
933 sub remove_accessors {
935 $self->SUPER::remove_accessors(@_);
936 $self->remove_delegation if $self->has_handles;
940 sub install_delegation {
944 # Here we canonicalize the 'handles' option
945 # this will sort out any details and always
946 # return an hash of methods which we want
947 # to delagate to, see that method for details
948 my %handles = $self->_canonicalize_handles;
951 # install the delegation ...
952 my $associated_class = $self->associated_class;
953 foreach my $handle (keys %handles) {
954 my $method_to_call = $handles{$handle};
955 my $class_name = $associated_class->name;
956 my $name = "${class_name}::${handle}";
958 (!$associated_class->has_method($handle))
959 || $self->throw_error("You cannot overwrite a locally defined method ($handle) with a delegation", method_name => $handle);
962 # handles is not allowed to delegate
963 # any of these methods, as they will
964 # override the ones in your class, which
965 # is almost certainly not what you want.
967 # FIXME warn when $handle was explicitly specified, but not if the source is a regex or something
968 #cluck("Not delegating method '$handle' because it is a core method") and
969 next if $class_name->isa("Moose::Object") and $handle =~ /^BUILD|DEMOLISH$/ || Moose::Object->can($handle);
971 my $method = $self->_make_delegation_method($handle, $method_to_call);
973 $self->associated_class->add_method($method->name, $method);
974 $self->associate_method($method);
978 sub remove_delegation {
980 my %handles = $self->_canonicalize_handles;
981 my $associated_class = $self->associated_class;
982 foreach my $handle (keys %handles) {
983 next unless any { $handle eq $_ }
985 @{ $self->associated_methods };
986 $self->associated_class->remove_method($handle);
990 # private methods to help delegation ...
992 sub _canonicalize_handles {
994 my $handles = $self->handles;
995 if (my $handle_type = ref($handles)) {
996 if ($handle_type eq 'HASH') {
999 elsif ($handle_type eq 'ARRAY') {
1000 return map { $_ => $_ } @{$handles};
1002 elsif ($handle_type eq 'Regexp') {
1003 ($self->has_type_constraint)
1004 || $self->throw_error("Cannot delegate methods based on a Regexp without a type constraint (isa)", data => $handles);
1005 return map { ($_ => $_) }
1006 grep { /$handles/ } $self->_get_delegate_method_list;
1008 elsif ($handle_type eq 'CODE') {
1009 return $handles->($self, $self->_find_delegate_metaclass);
1011 elsif (blessed($handles) && $handles->isa('Moose::Meta::TypeConstraint::DuckType')) {
1012 return map { $_ => $_ } @{ $handles->methods };
1014 elsif (blessed($handles) && $handles->isa('Moose::Meta::TypeConstraint::Role')) {
1015 $handles = $handles->role;
1018 $self->throw_error("Unable to canonicalize the 'handles' option with $handles", data => $handles);
1022 Class::MOP::load_class($handles);
1023 my $role_meta = Class::MOP::class_of($handles);
1025 (blessed $role_meta && $role_meta->isa('Moose::Meta::Role'))
1026 || $self->throw_error("Unable to canonicalize the 'handles' option with $handles because its metaclass is not a Moose::Meta::Role", data => $handles);
1028 return map { $_ => $_ }
1030 grep { !$_->isa('Class::MOP::Method::Meta') } (
1031 $role_meta->_get_local_methods,
1032 $role_meta->get_required_method_list,
1036 sub _get_delegate_method_list {
1038 my $meta = $self->_find_delegate_metaclass;
1039 if ($meta->isa('Class::MOP::Class')) {
1040 return map { $_->name } # NOTE: !never! delegate &meta
1041 grep { $_->package_name ne 'Moose::Object' && !$_->isa('Class::MOP::Method::Meta') }
1042 $meta->get_all_methods;
1044 elsif ($meta->isa('Moose::Meta::Role')) {
1045 return $meta->get_method_list;
1048 $self->throw_error("Unable to recognize the delegate metaclass '$meta'", data => $meta);
1052 sub _find_delegate_metaclass {
1054 if (my $class = $self->_isa_metadata) {
1055 unless ( Class::MOP::is_class_loaded($class) ) {
1058 'The %s attribute is trying to delegate to a class which has not been loaded - %s',
1063 # we might be dealing with a non-Moose class,
1064 # and need to make our own metaclass. if there's
1065 # already a metaclass, it will be returned
1066 return Class::MOP::Class->initialize($class);
1068 elsif (my $role = $self->_does_metadata) {
1069 unless ( Class::MOP::is_class_loaded($class) ) {
1072 'The %s attribute is trying to delegate to a role which has not been loaded - %s',
1078 return Class::MOP::class_of($role);
1081 $self->throw_error("Cannot find delegate metaclass for attribute " . $self->name);
1085 sub delegation_metaclass { 'Moose::Meta::Method::Delegation' }
1087 sub _make_delegation_method {
1088 my ( $self, $handle_name, $method_to_call ) = @_;
1090 my @curried_arguments;
1092 ($method_to_call, @curried_arguments) = @$method_to_call
1093 if 'ARRAY' eq ref($method_to_call);
1095 return $self->delegation_metaclass->new(
1096 name => $handle_name,
1097 package_name => $self->associated_class->name,
1099 delegate_to_method => $method_to_call,
1100 curried_arguments => \@curried_arguments,
1104 sub _coerce_and_verify {
1107 my $instance = shift;
1109 return $val unless $self->has_type_constraint;
1111 $val = $self->type_constraint->coerce($val)
1112 if $self->should_coerce && $self->type_constraint->has_coercion;
1114 $self->verify_against_type_constraint($val, instance => $instance);
1119 sub verify_against_type_constraint {
1123 return 1 if !$self->has_type_constraint;
1125 my $type_constraint = $self->type_constraint;
1127 $type_constraint->check($val)
1128 || $self->throw_error("Attribute ("
1130 . ") does not pass the type constraint because: "
1131 . $type_constraint->get_message($val), data => $val, @_);
1134 package Moose::Meta::Attribute::Custom::Moose;
1135 sub register_implementation { 'Moose::Meta::Attribute' }
1145 Moose::Meta::Attribute - The Moose attribute metaclass
1149 This class is a subclass of L<Class::MOP::Attribute> that provides
1150 additional Moose-specific functionality.
1152 To really understand this class, you will need to start with the
1153 L<Class::MOP::Attribute> documentation. This class can be understood
1154 as a set of additional features on top of the basic feature provided
1155 by that parent class.
1159 C<Moose::Meta::Attribute> is a subclass of L<Class::MOP::Attribute>.
1163 Many of the documented below override methods in
1164 L<Class::MOP::Attribute> and add Moose specific features.
1170 =item B<< Moose::Meta::Attribute->new(%options) >>
1172 This method overrides the L<Class::MOP::Attribute> constructor.
1174 Many of the options below are described in more detail in the
1175 L<Moose::Manual::Attributes> document.
1177 It adds the following options to the constructor:
1181 =item * is => 'ro', 'rw', 'bare'
1183 This provides a shorthand for specifying the C<reader>, C<writer>, or
1184 C<accessor> names. If the attribute is read-only ('ro') then it will
1185 have a C<reader> method with the same attribute as the name.
1187 If it is read-write ('rw') then it will have an C<accessor> method
1188 with the same name. If you provide an explicit C<writer> for a
1189 read-write attribute, then you will have a C<reader> with the same
1190 name as the attribute, and a C<writer> with the name you provided.
1192 Use 'bare' when you are deliberately not installing any methods
1193 (accessor, reader, etc.) associated with this attribute; otherwise,
1194 Moose will issue a deprecation warning when this attribute is added to a
1197 =item * isa => $type
1199 This option accepts a type. The type can be a string, which should be
1200 a type name. If the type name is unknown, it is assumed to be a class
1203 This option can also accept a L<Moose::Meta::TypeConstraint> object.
1205 If you I<also> provide a C<does> option, then your C<isa> option must
1206 be a class name, and that class must do the role specified with
1209 =item * does => $role
1211 This is short-hand for saying that the attribute's type must be an
1212 object which does the named role.
1214 =item * coerce => $bool
1216 This option is only valid for objects with a type constraint
1217 (C<isa>) that defined a coercion. If this is true, then coercions will be applied whenever
1218 this attribute is set.
1220 You can make both this and the C<weak_ref> option true.
1222 =item * trigger => $sub
1224 This option accepts a subroutine reference, which will be called after
1225 the attribute is set.
1227 =item * required => $bool
1229 An attribute which is required must be provided to the constructor. An
1230 attribute which is required can also have a C<default> or C<builder>,
1231 which will satisfy its required-ness.
1233 A required attribute must have a C<default>, C<builder> or a
1234 non-C<undef> C<init_arg>
1236 =item * lazy => $bool
1238 A lazy attribute must have a C<default> or C<builder>. When an
1239 attribute is lazy, the default value will not be calculated until the
1242 =item * weak_ref => $bool
1244 If this is true, the attribute's value will be stored as a weak
1247 =item * auto_deref => $bool
1249 If this is true, then the reader will dereference the value when it is
1250 called. The attribute must have a type constraint which defines the
1251 attribute as an array or hash reference.
1253 =item * lazy_build => $bool
1255 Setting this to true makes the attribute lazy and provides a number of
1263 is equivalent to this:
1268 builder => '_build_size',
1269 clearer => 'clear_size',
1270 predicate => 'has_size',
1274 If your attribute name starts with an underscore (C<_>), then the clearer
1275 and predicate will as well:
1287 builder => '_build__size',
1288 clearer => '_clear_size',
1289 predicate => '_has_size',
1292 Note the doubled underscore in the builder name. Internally, Moose
1293 simply prepends the attribute name with "_build_" to come up with the
1296 =item * documentation
1298 An arbitrary string that can be retrieved later by calling C<<
1299 $attr->documentation >>.
1303 =item B<< $attr->clone(%options) >>
1305 This creates a new attribute based on attribute being cloned. You must
1306 supply a C<name> option to provide a new name for the attribute.
1308 The C<%options> can only specify options handled by
1309 L<Class::MOP::Attribute>.
1313 =head2 Value management
1317 =item B<< $attr->initialize_instance_slot($meta_instance, $instance, $params) >>
1319 This method is used internally to initialize the attribute's slot in
1320 the object C<$instance>.
1322 This overrides the L<Class::MOP::Attribute> method to handle lazy
1323 attributes, weak references, and type constraints.
1329 eval { $point->meta->get_attribute('x')->set_value($point, 'forty-two') };
1334 I<Attribute (x) does not pass the type constraint (Int) with 'forty-two'>
1336 Before setting the value, a check is made on the type constraint of
1337 the attribute, if it has one, to see if the value passes it. If the
1338 value fails to pass, the set operation dies with a L</throw_error>.
1340 Any coercion to convert values is done before checking the type constraint.
1342 To check a value against a type constraint before setting it, fetch the
1343 attribute instance using L<Class::MOP::Class/find_attribute_by_name>,
1344 fetch the type_constraint from the attribute using L<Moose::Meta::Attribute/type_constraint>
1345 and call L<Moose::Meta::TypeConstraint/check>. See L<Moose::Cookbook::Basics::Recipe4>
1350 =head2 Attribute Accessor generation
1354 =item B<< $attr->install_accessors >>
1356 This method overrides the parent to also install delegation methods.
1358 If, after installing all methods, the attribute object has no associated
1359 methods, it throws an error unless C<< is => 'bare' >> was passed to the
1360 attribute constructor. (Trying to add an attribute that has no associated
1361 methods is almost always an error.)
1363 =item B<< $attr->remove_accessors >>
1365 This method overrides the parent to also remove delegation methods.
1367 =item B<< $attr->inline_set($instance_var, $value_var) >>
1369 This method return a code snippet suitable for inlining the relevant
1370 operation. It expect strings containing variable names to be used in the
1371 inlining, like C<'$self'> or C<'$_[1]'>.
1373 =item B<< $attr->install_delegation >>
1375 This method adds its delegation methods to the attribute's associated
1376 class, if it has any to add.
1378 =item B<< $attr->remove_delegation >>
1380 This method remove its delegation methods from the attribute's
1383 =item B<< $attr->accessor_metaclass >>
1385 Returns the accessor metaclass name, which defaults to
1386 L<Moose::Meta::Method::Accessor>.
1388 =item B<< $attr->delegation_metaclass >>
1390 Returns the delegation metaclass name, which defaults to
1391 L<Moose::Meta::Method::Delegation>.
1395 =head2 Additional Moose features
1397 These methods are not found in the superclass. They support features
1402 =item B<< $attr->does($role) >>
1404 This indicates whether the I<attribute itself> does the given
1405 role. The role can be given as a full class name, or as a resolvable
1408 Note that this checks the attribute itself, not its type constraint,
1409 so it is checking the attribute's metaclass and any traits applied to
1412 =item B<< Moose::Meta::Class->interpolate_class_and_new($name, %options) >>
1414 This is an alternate constructor that handles the C<metaclass> and
1417 Effectively, this method is a factory that finds or creates the
1418 appropriate class for the given C<metaclass> and/or C<traits>.
1420 Once it has the appropriate class, it will call C<< $class->new($name,
1421 %options) >> on that class.
1423 =item B<< $attr->clone_and_inherit_options(%options) >>
1425 This method supports the C<has '+foo'> feature. It does various bits
1426 of processing on the supplied C<%options> before ultimately calling
1427 the C<clone> method.
1429 One of its main tasks is to make sure that the C<%options> provided
1430 does not include the options returned by the
1431 C<illegal_options_for_inheritance> method.
1433 =item B<< $attr->illegal_options_for_inheritance >>
1435 This returns a blacklist of options that can not be overridden in a
1436 subclass's attribute definition.
1438 This exists to allow a custom metaclass to change or add to the list
1439 of options which can not be changed.
1441 =item B<< $attr->type_constraint >>
1443 Returns the L<Moose::Meta::TypeConstraint> object for this attribute,
1446 =item B<< $attr->has_type_constraint >>
1448 Returns true if this attribute has a type constraint.
1450 =item B<< $attr->verify_against_type_constraint($value) >>
1452 Given a value, this method returns true if the value is valid for the
1453 attribute's type constraint. If the value is not valid, it throws an
1456 =item B<< $attr->handles >>
1458 This returns the value of the C<handles> option passed to the
1461 =item B<< $attr->has_handles >>
1463 Returns true if this attribute performs delegation.
1465 =item B<< $attr->is_weak_ref >>
1467 Returns true if this attribute stores its value as a weak reference.
1469 =item B<< $attr->is_required >>
1471 Returns true if this attribute is required to have a value.
1473 =item B<< $attr->is_lazy >>
1475 Returns true if this attribute is lazy.
1477 =item B<< $attr->is_lazy_build >>
1479 Returns true if the C<lazy_build> option was true when passed to the
1482 =item B<< $attr->should_coerce >>
1484 Returns true if the C<coerce> option passed to the constructor was
1487 =item B<< $attr->should_auto_deref >>
1489 Returns true if the C<auto_deref> option passed to the constructor was
1492 =item B<< $attr->trigger >>
1494 This is the subroutine reference that was in the C<trigger> option
1495 passed to the constructor, if any.
1497 =item B<< $attr->has_trigger >>
1499 Returns true if this attribute has a trigger set.
1501 =item B<< $attr->documentation >>
1503 Returns the value that was in the C<documentation> option passed to
1504 the constructor, if any.
1506 =item B<< $attr->has_documentation >>
1508 Returns true if this attribute has any documentation.
1510 =item B<< $attr->applied_traits >>
1512 This returns an array reference of all the traits which were applied
1513 to this attribute. If none were applied, this returns C<undef>.
1515 =item B<< $attr->has_applied_traits >>
1517 Returns true if this attribute has any traits applied.
1523 See L<Moose/BUGS> for details on reporting bugs.
1527 Stevan Little E<lt>stevan@iinteractive.comE<gt>
1529 Yuval Kogman E<lt>nothingmuch@woobling.comE<gt>
1531 =head1 COPYRIGHT AND LICENSE
1533 Copyright 2006-2010 by Infinity Interactive, Inc.
1535 L<http://www.iinteractive.com>
1537 This library is free software; you can redistribute it and/or modify
1538 it under the same terms as Perl itself.