2 package Moose::Meta::Attribute;
8 use Class::Load qw(is_class_loaded load_class);
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 my $has_foreign_options = 0;
134 while ($i < @$traits) {
135 my $trait = $traits->[$i++];
136 next if ref($trait); # options to a trait we discarded
138 $trait = Moose::Util::resolve_metatrait_alias(Attribute => $trait)
141 next if $class->does($trait);
143 push @traits, $trait;
146 if ($traits->[$i] && ref($traits->[$i])) {
147 $has_foreign_options = 1
148 if any { $_ ne '-alias' && $_ ne '-excludes' } keys %{ $traits->[$i] };
150 push @traits, $traits->[$i++];
156 superclasses => [ $class ],
157 roles => [ @traits ],
160 if ($has_foreign_options) {
161 $options{weaken} = 0;
167 my $anon_class = Moose::Meta::Class->create_anon_class(%options);
168 $class = $anon_class->name;
172 return ( wantarray ? ( $class, @traits ) : $class );
177 # method-generating options shouldn't be overridden
178 sub illegal_options_for_inheritance {
179 qw(reader writer accessor clearer predicate)
183 # This method *must* be able to handle
184 # Class::MOP::Attribute instances as
185 # well. Yes, I know that is wrong, but
186 # apparently we didn't realize it was
187 # doing that and now we have some code
188 # which is dependent on it. The real
189 # solution of course is to push this
190 # feature back up into Class::MOP::Attribute
191 # but I not right now, I am too lazy.
192 # However if you are reading this and
193 # looking for something to do,.. please
196 sub clone_and_inherit_options {
197 my ($self, %options) = @_;
200 # we may want to extends a Class::MOP::Attribute
201 # in which case we need to be able to use the
202 # core set of legal options that have always
203 # been here. But we allows Moose::Meta::Attribute
204 # instances to changes them.
206 my @illegal_options = $self->can('illegal_options_for_inheritance')
207 ? $self->illegal_options_for_inheritance
210 my @found_illegal_options = grep { exists $options{$_} && exists $self->{$_} ? $_ : undef } @illegal_options;
211 (scalar @found_illegal_options == 0)
212 || $self->throw_error("Illegal inherited options => (" . (join ', ' => @found_illegal_options) . ")", data => \%options);
216 if (blessed($options{isa}) && $options{isa}->isa('Moose::Meta::TypeConstraint')) {
217 $type_constraint = $options{isa};
220 $type_constraint = Moose::Util::TypeConstraints::find_or_create_isa_type_constraint($options{isa}, { package_defined_in => $options{definition_context}->{package} });
221 (defined $type_constraint)
222 || $self->throw_error("Could not find the type constraint '" . $options{isa} . "'", data => $options{isa});
225 $options{type_constraint} = $type_constraint;
228 if ($options{does}) {
230 if (blessed($options{does}) && $options{does}->isa('Moose::Meta::TypeConstraint')) {
231 $type_constraint = $options{does};
234 $type_constraint = Moose::Util::TypeConstraints::find_or_create_does_type_constraint($options{does}, { package_defined_in => $options{definition_context}->{package} });
235 (defined $type_constraint)
236 || $self->throw_error("Could not find the type constraint '" . $options{does} . "'", data => $options{does});
239 $options{type_constraint} = $type_constraint;
243 # this doesn't apply to Class::MOP::Attributes,
244 # so we can ignore it for them.
246 if ($self->can('interpolate_class')) {
247 ( $options{metaclass}, my @traits ) = $self->interpolate_class(\%options);
250 my @all_traits = grep { $seen{$_}++ } @{ $self->applied_traits || [] }, @traits;
251 $options{traits} = \@all_traits if @all_traits;
254 # This method can be called on a CMOP::Attribute object, so we need to
255 # make sure we can call this method.
256 $self->_process_lazy_build_option( $self->name, \%options )
257 if $self->can('_process_lazy_build_option');
259 $self->clone(%options);
263 my ( $self, %params ) = @_;
265 my $class = delete $params{metaclass} || ref $self;
267 my ( @init, @non_init );
269 foreach my $attr ( grep { $_->has_value($self) } Class::MOP::class_of($self)->get_all_attributes ) {
270 push @{ $attr->has_init_arg ? \@init : \@non_init }, $attr;
273 my %new_params = ( ( map { $_->init_arg => $_->get_value($self) } @init ), %params );
275 my $name = delete $new_params{name};
277 my $clone = $class->new($name, %new_params, __hack_no_process_options => 1 );
279 foreach my $attr ( @non_init ) {
280 $attr->set_value($clone, $attr->get_value($self));
286 sub _process_options {
287 my ( $class, $name, $options ) = @_;
289 $class->_process_is_option( $name, $options );
290 $class->_process_isa_option( $name, $options );
291 $class->_process_does_option( $name, $options );
292 $class->_process_coerce_option( $name, $options );
293 $class->_process_trigger_option( $name, $options );
294 $class->_process_auto_deref_option( $name, $options );
295 $class->_process_lazy_build_option( $name, $options );
296 $class->_process_lazy_option( $name, $options );
297 $class->_process_required_option( $name, $options );
300 sub _process_is_option {
301 my ( $class, $name, $options ) = @_;
303 return unless $options->{is};
305 ### -------------------------
306 ## is => ro, writer => _foo # turns into (reader => foo, writer => _foo) as before
307 ## is => rw, writer => _foo # turns into (reader => foo, writer => _foo)
308 ## is => rw, accessor => _foo # turns into (accessor => _foo)
309 ## is => ro, accessor => _foo # error, accesor is rw
310 ### -------------------------
312 if ( $options->{is} eq 'ro' ) {
314 "Cannot define an accessor name on a read-only attribute, accessors are read/write",
316 if exists $options->{accessor};
317 $options->{reader} ||= $name;
319 elsif ( $options->{is} eq 'rw' ) {
320 if ( $options->{writer} ) {
321 $options->{reader} ||= $name;
324 $options->{accessor} ||= $name;
327 elsif ( $options->{is} eq 'bare' ) {
329 # do nothing, but don't complain (later) about missing methods
332 $class->throw_error( "I do not understand this option (is => "
334 . ") on attribute ($name)", data => $options->{is} );
338 sub _process_isa_option {
339 my ( $class, $name, $options ) = @_;
341 return unless exists $options->{isa};
343 if ( exists $options->{does} ) {
344 if ( try { $options->{isa}->can('does') } ) {
345 ( $options->{isa}->does( $options->{does} ) )
346 || $class->throw_error(
347 "Cannot have an isa option and a does option if the isa does not do the does on attribute ($name)",
352 "Cannot have an isa option which cannot ->does() on attribute ($name)",
357 # allow for anon-subtypes here ...
358 if ( blessed( $options->{isa} )
359 && $options->{isa}->isa('Moose::Meta::TypeConstraint') ) {
360 $options->{type_constraint} = $options->{isa};
363 $options->{type_constraint}
364 = Moose::Util::TypeConstraints::find_or_create_isa_type_constraint(
366 { package_defined_in => $options->{definition_context}->{package} }
371 sub _process_does_option {
372 my ( $class, $name, $options ) = @_;
374 return unless exists $options->{does} && ! exists $options->{isa};
376 # allow for anon-subtypes here ...
377 if ( blessed( $options->{does} )
378 && $options->{does}->isa('Moose::Meta::TypeConstraint') ) {
379 $options->{type_constraint} = $options->{does};
382 $options->{type_constraint}
383 = Moose::Util::TypeConstraints::find_or_create_does_type_constraint(
385 { package_defined_in => $options->{definition_context}->{package} }
390 sub _process_coerce_option {
391 my ( $class, $name, $options ) = @_;
393 return unless $options->{coerce};
395 ( exists $options->{type_constraint} )
396 || $class->throw_error(
397 "You cannot have coercion without specifying a type constraint on attribute ($name)",
401 "You cannot have a weak reference to a coerced value on attribute ($name)",
403 if $options->{weak_ref};
405 unless ( $options->{type_constraint}->has_coercion ) {
406 my $type = $options->{type_constraint}->name;
408 Moose::Deprecated::deprecated(
409 feature => 'coerce without coercion',
411 "You cannot coerce an attribute ($name) unless its type ($type) has a coercion"
416 sub _process_trigger_option {
417 my ( $class, $name, $options ) = @_;
419 return unless exists $options->{trigger};
421 ( 'CODE' eq ref $options->{trigger} )
422 || $class->throw_error("Trigger must be a CODE ref on attribute ($name)", data => $options->{trigger});
425 sub _process_auto_deref_option {
426 my ( $class, $name, $options ) = @_;
428 return unless $options->{auto_deref};
430 ( exists $options->{type_constraint} )
431 || $class->throw_error(
432 "You cannot auto-dereference without specifying a type constraint on attribute ($name)",
435 ( $options->{type_constraint}->is_a_type_of('ArrayRef')
436 || $options->{type_constraint}->is_a_type_of('HashRef') )
437 || $class->throw_error(
438 "You cannot auto-dereference anything other than a ArrayRef or HashRef on attribute ($name)",
442 sub _process_lazy_build_option {
443 my ( $class, $name, $options ) = @_;
445 return unless $options->{lazy_build};
448 "You can not use lazy_build and default for the same attribute ($name)",
450 if exists $options->{default};
452 $options->{lazy} = 1;
453 $options->{builder} ||= "_build_${name}";
455 if ( $name =~ /^_/ ) {
456 $options->{clearer} ||= "_clear${name}";
457 $options->{predicate} ||= "_has${name}";
460 $options->{clearer} ||= "clear_${name}";
461 $options->{predicate} ||= "has_${name}";
465 sub _process_lazy_option {
466 my ( $class, $name, $options ) = @_;
468 return unless $options->{lazy};
470 ( exists $options->{default} || defined $options->{builder} )
471 || $class->throw_error(
472 "You cannot have a lazy attribute ($name) without specifying a default value for it",
476 sub _process_required_option {
477 my ( $class, $name, $options ) = @_;
482 ( !exists $options->{init_arg} || defined $options->{init_arg} )
483 || exists $options->{default}
484 || defined $options->{builder}
488 "You cannot have a required attribute ($name) without a default, builder, or an init_arg",
493 sub initialize_instance_slot {
494 my ($self, $meta_instance, $instance, $params) = @_;
495 my $init_arg = $self->init_arg();
496 # try to fetch the init arg from the %params ...
500 if ( defined($init_arg) and exists $params->{$init_arg}) {
501 $val = $params->{$init_arg};
505 # skip it if it's lazy
506 return if $self->is_lazy;
507 # and die if it's required and doesn't have a default value
508 $self->throw_error("Attribute (" . $self->name . ") is required", object => $instance, data => $params)
509 if $self->is_required && !$self->has_default && !$self->has_builder;
511 # if nothing was in the %params, we can use the
512 # attribute's default value (if it has one)
513 if ($self->has_default) {
514 $val = $self->default($instance);
517 elsif ($self->has_builder) {
518 $val = $self->_call_builder($instance);
523 return unless $value_is_set;
525 $val = $self->_coerce_and_verify( $val, $instance );
527 $self->set_initial_value($instance, $val);
529 if ( ref $val && $self->is_weak_ref ) {
530 $self->_weaken_value($instance);
535 my ( $self, $instance ) = @_;
537 my $builder = $self->builder();
539 return $instance->$builder()
540 if $instance->can( $self->builder );
542 $self->throw_error( blessed($instance)
543 . " does not support builder method '"
545 . "' for attribute '"
554 sub _make_initializer_writer_callback {
556 my ($meta_instance, $instance, $slot_name) = @_;
557 my $old_callback = $self->SUPER::_make_initializer_writer_callback(@_);
559 $old_callback->($self->_coerce_and_verify($_[0], $instance));
564 my ($self, $instance, @args) = @_;
565 my $value = $args[0];
567 my $attr_name = quotemeta($self->name);
569 if ($self->is_required and not @args) {
570 $self->throw_error("Attribute ($attr_name) is required", object => $instance);
573 $value = $self->_coerce_and_verify( $value, $instance );
576 if ( $self->has_trigger && $self->has_value($instance) ) {
577 @old = $self->get_value($instance, 'for trigger');
580 $self->SUPER::set_value($instance, $value);
582 if ( ref $value && $self->is_weak_ref ) {
583 $self->_weaken_value($instance);
586 if ($self->has_trigger) {
587 $self->trigger->($instance, $value, @old);
591 sub _inline_set_value {
593 my ($instance, $value, $tc, $coercion, $message, $for_constructor) = @_;
597 $tc ||= '$type_constraint';
598 $coercion ||= '$type_coercion';
599 $message ||= '$type_message';
602 if ($self->_writer_value_needs_copy) {
603 push @code, $self->_inline_copy_value($value, $copy);
607 # constructors already handle required checks
608 push @code, $self->_inline_check_required
609 unless $for_constructor;
611 push @code, $self->_inline_tc_code($value, $tc, $coercion, $message);
613 # constructors do triggers all at once at the end
614 push @code, $self->_inline_get_old_value_for_trigger($instance, $old)
615 unless $for_constructor;
618 $self->SUPER::_inline_set_value($instance, $value),
619 $self->_inline_weaken_value($instance, $value),
622 # constructors do triggers all at once at the end
623 push @code, $self->_inline_trigger($instance, $value, $old)
624 unless $for_constructor;
629 sub _writer_value_needs_copy {
631 return $self->should_coerce;
634 sub _inline_copy_value {
636 my ($value, $copy) = @_;
638 return 'my ' . $copy . ' = ' . $value . ';'
641 sub _inline_check_required {
644 return unless $self->is_required;
646 my $attr_name = quotemeta($self->name);
650 $self->_inline_throw_error(
651 '"Attribute (' . $attr_name . ') is required, so cannot '
652 . 'be set to undef"' # defined $_[1] is not good enough
658 sub _inline_tc_code {
660 my ($value, $tc, $coercion, $message, $is_lazy) = @_;
662 $self->_inline_check_coercion(
663 $value, $tc, $coercion, $is_lazy,
665 $self->_inline_check_constraint(
666 $value, $tc, $message, $is_lazy,
671 sub _inline_check_coercion {
673 my ($value, $tc, $coercion) = @_;
675 return unless $self->should_coerce && $self->type_constraint->has_coercion;
677 if ( $self->type_constraint->can_be_inlined ) {
679 'if (! (' . $self->type_constraint->_inline_check($value) . ')) {',
680 $value . ' = ' . $coercion . '->(' . $value . ');',
686 'if (!' . $tc . '->(' . $value . ')) {',
687 $value . ' = ' . $coercion . '->(' . $value . ');',
693 sub _inline_check_constraint {
695 my ($value, $tc, $message) = @_;
697 return unless $self->has_type_constraint;
699 my $attr_name = quotemeta($self->name);
701 if ( $self->type_constraint->can_be_inlined ) {
703 'if (! (' . $self->type_constraint->_inline_check($value) . ')) {',
704 $self->_inline_throw_error(
705 '"Attribute (' . $attr_name . ') does not pass the type '
706 . 'constraint because: " . '
707 . 'do { local $_ = ' . $value . '; '
708 . $message . '->(' . $value . ')'
717 'if (!' . $tc . '->(' . $value . ')) {',
718 $self->_inline_throw_error(
719 '"Attribute (' . $attr_name . ') does not pass the type '
720 . 'constraint because: " . '
721 . 'do { local $_ = ' . $value . '; '
722 . $message . '->(' . $value . ')'
731 sub _inline_get_old_value_for_trigger {
733 my ($instance, $old) = @_;
735 return unless $self->has_trigger;
738 'my ' . $old . ' = ' . $self->_inline_instance_has($instance),
739 '? ' . $self->_inline_instance_get($instance),
744 sub _inline_weaken_value {
746 my ($instance, $value) = @_;
748 return unless $self->is_weak_ref;
750 my $mi = $self->associated_class->get_meta_instance;
752 $mi->inline_weaken_slot_value($instance, $self->name),
753 'if ref ' . $value . ';',
757 sub _inline_trigger {
759 my ($instance, $value, $old) = @_;
761 return unless $self->has_trigger;
763 return '$trigger->(' . $instance . ', ' . $value . ', ' . $old . ');';
766 sub _eval_environment {
771 $env->{'$trigger'} = \($self->trigger)
772 if $self->has_trigger;
773 $env->{'$attr_default'} = \($self->default)
774 if $self->has_default;
776 if ($self->has_type_constraint) {
777 my $tc_obj = $self->type_constraint;
779 $env->{'$type_constraint'} = \(
780 $tc_obj->_compiled_type_constraint
781 ) unless $tc_obj->can_be_inlined;
782 # these two could probably get inlined versions too
783 $env->{'$type_coercion'} = \(
784 $tc_obj->coercion->_compiled_type_coercion
785 ) if $tc_obj->has_coercion;
786 $env->{'$type_message'} = \(
787 $tc_obj->has_message ? $tc_obj->message : $tc_obj->_default_message
790 $env = { %$env, %{ $tc_obj->inline_environment } };
794 $env->{'$attr'} = \$self
795 if $self->has_initializer && $self->is_lazy;
796 # pretty sure this is only going to be closed over if you use a custom
797 # error class at this point, but we should still get rid of this
799 $env->{'$meta'} = \($self->associated_class);
805 my ( $self, $instance ) = @_;
807 my $meta_instance = Class::MOP::Class->initialize( blessed($instance) )
810 $meta_instance->weaken_slot_value( $instance, $self->name );
814 my ($self, $instance, $for_trigger) = @_;
816 if ($self->is_lazy) {
817 unless ($self->has_value($instance)) {
819 if ($self->has_default) {
820 $value = $self->default($instance);
821 } elsif ( $self->has_builder ) {
822 $value = $self->_call_builder($instance);
825 $value = $self->_coerce_and_verify( $value, $instance );
827 $self->set_initial_value($instance, $value);
829 if ( ref $value && $self->is_weak_ref ) {
830 $self->_weaken_value($instance);
835 if ( $self->should_auto_deref && ! $for_trigger ) {
837 my $type_constraint = $self->type_constraint;
839 if ($type_constraint->is_a_type_of('ArrayRef')) {
840 my $rv = $self->SUPER::get_value($instance);
841 return unless defined $rv;
842 return wantarray ? @{ $rv } : $rv;
844 elsif ($type_constraint->is_a_type_of('HashRef')) {
845 my $rv = $self->SUPER::get_value($instance);
846 return unless defined $rv;
847 return wantarray ? %{ $rv } : $rv;
850 $self->throw_error("Can not auto de-reference the type constraint '" . $type_constraint->name . "'", object => $instance, type_constraint => $type_constraint);
856 return $self->SUPER::get_value($instance);
860 sub _inline_get_value {
862 my ($instance, $tc, $coercion, $message) = @_;
864 my $slot_access = $self->_inline_instance_get($instance);
865 $tc ||= '$type_constraint';
866 $coercion ||= '$type_coercion';
867 $message ||= '$type_message';
870 $self->_inline_check_lazy($instance, $tc, $coercion, $message),
871 $self->_inline_return_auto_deref($slot_access),
875 sub _inline_check_lazy {
877 my ($instance, $tc, $coercion, $message) = @_;
879 return unless $self->is_lazy;
881 my $slot_exists = $self->_inline_instance_has($instance);
884 'if (!' . $slot_exists . ') {',
885 $self->_inline_init_from_default($instance, '$default', $tc, $coercion, $message, 'lazy'),
890 sub _inline_init_from_default {
892 my ($instance, $default, $tc, $coercion, $message, $for_lazy) = @_;
894 if (!($self->has_default || $self->has_builder)) {
896 'You cannot have a lazy attribute '
897 . '(' . $self->name . ') '
898 . 'without specifying a default value for it',
904 $self->_inline_generate_default($instance, $default),
905 # intentionally not using _inline_tc_code, since that can be overridden
906 # to do things like possibly only do member tc checks, which isn't
907 # appropriate for checking the result of a default
908 $self->has_type_constraint
909 ? ($self->_inline_check_coercion($default, $tc, $coercion, $for_lazy),
910 $self->_inline_check_constraint($default, $tc, $message, $for_lazy))
912 $self->_inline_init_slot($instance, $default),
913 $self->_inline_weaken_value($instance, $default),
917 sub _inline_generate_default {
919 my ($instance, $default) = @_;
921 if ($self->has_default) {
922 my $source = 'my ' . $default . ' = $attr_default';
923 $source .= '->(' . $instance . ')'
924 if $self->is_default_a_coderef;
925 return $source . ';';
927 elsif ($self->has_builder) {
928 my $builder = B::perlstring($self->builder);
929 my $builder_str = quotemeta($self->builder);
930 my $attr_name_str = quotemeta($self->name);
932 'my ' . $default . ';',
933 'if (my $builder = ' . $instance . '->can(' . $builder . ')) {',
934 $default . ' = ' . $instance . '->$builder;',
937 'my $class = ref(' . $instance . ') || ' . $instance . ';',
938 $self->_inline_throw_error(
939 '"$class does not support builder method '
940 . '\'' . $builder_str . '\' for attribute '
941 . '\'' . $attr_name_str . '\'"'
948 "Can't generate a default for " . $self->name
949 . " since no default or builder was specified"
954 sub _inline_init_slot {
956 my ($inv, $value) = @_;
958 if ($self->has_initializer) {
959 return '$attr->set_initial_value(' . $inv . ', ' . $value . ');';
962 return $self->_inline_instance_set($inv, $value) . ';';
966 sub _inline_return_auto_deref {
969 return 'return ' . $self->_auto_deref(@_) . ';';
974 my ($ref_value) = @_;
976 return $ref_value unless $self->should_auto_deref;
978 my $type_constraint = $self->type_constraint;
981 if ($type_constraint->is_a_type_of('ArrayRef')) {
984 elsif ($type_constraint->is_a_type_of('HashRef')) {
989 'Can not auto de-reference the type constraint \''
990 . $type_constraint->name
992 type_constraint => $type_constraint,
997 . '? ' . $sigil . '{ (' . $ref_value . ') || return } '
998 . ': (' . $ref_value . ')';
1001 ## installing accessors
1003 sub accessor_metaclass { 'Moose::Meta::Method::Accessor' }
1005 sub install_accessors {
1007 $self->SUPER::install_accessors(@_);
1008 $self->install_delegation if $self->has_handles;
1012 sub _check_associated_methods {
1015 @{ $self->associated_methods }
1016 || ($self->_is_metadata || '') eq 'bare'
1019 'Attribute (' . $self->name . ') of class '
1020 . $self->associated_class->name
1021 . ' has no associated methods'
1022 . ' (did you mean to provide an "is" argument?)'
1028 sub _process_accessors {
1030 my ($type, $accessor, $generate_as_inline_methods) = @_;
1032 $accessor = ( keys %$accessor )[0] if ( ref($accessor) || '' ) eq 'HASH';
1033 my $method = $self->associated_class->get_method($accessor);
1036 && $method->isa('Class::MOP::Method::Accessor')
1037 && $method->associated_attribute->name ne $self->name ) {
1039 my $other_attr_name = $method->associated_attribute->name;
1040 my $name = $self->name;
1043 "You are overwriting an accessor ($accessor) for the $other_attr_name attribute"
1044 . " with a new accessor method for the $name attribute" );
1049 && !$method->is_stub
1050 && !$method->isa('Class::MOP::Method::Accessor')
1051 && ( !$self->definition_context
1052 || $method->package_name eq $self->definition_context->{package} )
1056 "You are overwriting a locally defined method ($accessor) with "
1060 if ( !$self->associated_class->has_method($accessor)
1061 && $self->associated_class->has_package_symbol( '&' . $accessor ) ) {
1064 "You are overwriting a locally defined function ($accessor) with "
1068 $self->SUPER::_process_accessors(@_);
1071 sub remove_accessors {
1073 $self->SUPER::remove_accessors(@_);
1074 $self->remove_delegation if $self->has_handles;
1078 sub install_delegation {
1082 # Here we canonicalize the 'handles' option
1083 # this will sort out any details and always
1084 # return an hash of methods which we want
1085 # to delagate to, see that method for details
1086 my %handles = $self->_canonicalize_handles;
1089 # install the delegation ...
1090 my $associated_class = $self->associated_class;
1091 foreach my $handle (sort keys %handles) {
1092 my $method_to_call = $handles{$handle};
1093 my $class_name = $associated_class->name;
1094 my $name = "${class_name}::${handle}";
1096 if ( my $method = $associated_class->get_method($handle) ) {
1098 "You cannot overwrite a locally defined method ($handle) with a delegation",
1099 method_name => $handle
1100 ) unless $method->is_stub;
1104 # handles is not allowed to delegate
1105 # any of these methods, as they will
1106 # override the ones in your class, which
1107 # is almost certainly not what you want.
1109 # FIXME warn when $handle was explicitly specified, but not if the source is a regex or something
1110 #cluck("Not delegating method '$handle' because it is a core method") and
1111 next if $class_name->isa("Moose::Object") and $handle =~ /^BUILD|DEMOLISH$/ || Moose::Object->can($handle);
1113 my $method = $self->_make_delegation_method($handle, $method_to_call);
1115 $self->associated_class->add_method($method->name, $method);
1116 $self->associate_method($method);
1120 sub remove_delegation {
1122 my %handles = $self->_canonicalize_handles;
1123 my $associated_class = $self->associated_class;
1124 foreach my $handle (keys %handles) {
1125 next unless any { $handle eq $_ }
1127 @{ $self->associated_methods };
1128 $self->associated_class->remove_method($handle);
1132 # private methods to help delegation ...
1134 sub _canonicalize_handles {
1136 my $handles = $self->handles;
1137 if (my $handle_type = ref($handles)) {
1138 if ($handle_type eq 'HASH') {
1141 elsif ($handle_type eq 'ARRAY') {
1142 return map { $_ => $_ } @{$handles};
1144 elsif ($handle_type eq 'Regexp') {
1145 ($self->has_type_constraint)
1146 || $self->throw_error("Cannot delegate methods based on a Regexp without a type constraint (isa)", data => $handles);
1147 return map { ($_ => $_) }
1148 grep { /$handles/ } $self->_get_delegate_method_list;
1150 elsif ($handle_type eq 'CODE') {
1151 return $handles->($self, $self->_find_delegate_metaclass);
1153 elsif (blessed($handles) && $handles->isa('Moose::Meta::TypeConstraint::DuckType')) {
1154 return map { $_ => $_ } @{ $handles->methods };
1156 elsif (blessed($handles) && $handles->isa('Moose::Meta::TypeConstraint::Role')) {
1157 $handles = $handles->role;
1160 $self->throw_error("Unable to canonicalize the 'handles' option with $handles", data => $handles);
1164 load_class($handles);
1165 my $role_meta = Class::MOP::class_of($handles);
1167 (blessed $role_meta && $role_meta->isa('Moose::Meta::Role'))
1168 || $self->throw_error("Unable to canonicalize the 'handles' option with $handles because its metaclass is not a Moose::Meta::Role", data => $handles);
1170 return map { $_ => $_ }
1172 grep { !$_->isa('Class::MOP::Method::Meta') } (
1173 $role_meta->_get_local_methods,
1174 $role_meta->get_required_method_list,
1178 sub _get_delegate_method_list {
1180 my $meta = $self->_find_delegate_metaclass;
1181 if ($meta->isa('Class::MOP::Class')) {
1182 return map { $_->name } # NOTE: !never! delegate &meta
1183 grep { $_->package_name ne 'Moose::Object' && !$_->isa('Class::MOP::Method::Meta') }
1184 $meta->get_all_methods;
1186 elsif ($meta->isa('Moose::Meta::Role')) {
1187 return $meta->get_method_list;
1190 $self->throw_error("Unable to recognize the delegate metaclass '$meta'", data => $meta);
1194 sub _find_delegate_metaclass {
1196 if (my $class = $self->_isa_metadata) {
1197 unless ( is_class_loaded($class) ) {
1200 'The %s attribute is trying to delegate to a class which has not been loaded - %s',
1205 # we might be dealing with a non-Moose class,
1206 # and need to make our own metaclass. if there's
1207 # already a metaclass, it will be returned
1208 return Class::MOP::Class->initialize($class);
1210 elsif (my $role = $self->_does_metadata) {
1211 unless ( is_class_loaded($class) ) {
1214 'The %s attribute is trying to delegate to a role which has not been loaded - %s',
1220 return Class::MOP::class_of($role);
1223 $self->throw_error("Cannot find delegate metaclass for attribute " . $self->name);
1227 sub delegation_metaclass { 'Moose::Meta::Method::Delegation' }
1229 sub _make_delegation_method {
1230 my ( $self, $handle_name, $method_to_call ) = @_;
1232 my @curried_arguments;
1234 ($method_to_call, @curried_arguments) = @$method_to_call
1235 if 'ARRAY' eq ref($method_to_call);
1237 return $self->delegation_metaclass->new(
1238 name => $handle_name,
1239 package_name => $self->associated_class->name,
1241 delegate_to_method => $method_to_call,
1242 curried_arguments => \@curried_arguments,
1246 sub _coerce_and_verify {
1249 my $instance = shift;
1251 return $val unless $self->has_type_constraint;
1253 $val = $self->type_constraint->coerce($val)
1254 if $self->should_coerce && $self->type_constraint->has_coercion;
1256 $self->verify_against_type_constraint($val, instance => $instance);
1261 sub verify_against_type_constraint {
1265 return 1 if !$self->has_type_constraint;
1267 my $type_constraint = $self->type_constraint;
1269 $type_constraint->check($val)
1270 || $self->throw_error("Attribute ("
1272 . ") does not pass the type constraint because: "
1273 . $type_constraint->get_message($val), data => $val, @_);
1276 package Moose::Meta::Attribute::Custom::Moose;
1277 sub register_implementation { 'Moose::Meta::Attribute' }
1281 # ABSTRACT: The Moose attribute metaclass
1289 This class is a subclass of L<Class::MOP::Attribute> that provides
1290 additional Moose-specific functionality.
1292 To really understand this class, you will need to start with the
1293 L<Class::MOP::Attribute> documentation. This class can be understood
1294 as a set of additional features on top of the basic feature provided
1295 by that parent class.
1299 C<Moose::Meta::Attribute> is a subclass of L<Class::MOP::Attribute>.
1303 Many of the documented below override methods in
1304 L<Class::MOP::Attribute> and add Moose specific features.
1310 =item B<< Moose::Meta::Attribute->new($name, %options) >>
1312 This method overrides the L<Class::MOP::Attribute> constructor.
1314 Many of the options below are described in more detail in the
1315 L<Moose::Manual::Attributes> document.
1317 It adds the following options to the constructor:
1321 =item * is => 'ro', 'rw', 'bare'
1323 This provides a shorthand for specifying the C<reader>, C<writer>, or
1324 C<accessor> names. If the attribute is read-only ('ro') then it will
1325 have a C<reader> method with the same attribute as the name.
1327 If it is read-write ('rw') then it will have an C<accessor> method
1328 with the same name. If you provide an explicit C<writer> for a
1329 read-write attribute, then you will have a C<reader> with the same
1330 name as the attribute, and a C<writer> with the name you provided.
1332 Use 'bare' when you are deliberately not installing any methods
1333 (accessor, reader, etc.) associated with this attribute; otherwise,
1334 Moose will issue a deprecation warning when this attribute is added to a
1337 =item * isa => $type
1339 This option accepts a type. The type can be a string, which should be
1340 a type name. If the type name is unknown, it is assumed to be a class
1343 This option can also accept a L<Moose::Meta::TypeConstraint> object.
1345 If you I<also> provide a C<does> option, then your C<isa> option must
1346 be a class name, and that class must do the role specified with
1349 =item * does => $role
1351 This is short-hand for saying that the attribute's type must be an
1352 object which does the named role.
1354 =item * coerce => $bool
1356 This option is only valid for objects with a type constraint
1357 (C<isa>) that defined a coercion. If this is true, then coercions will be applied whenever
1358 this attribute is set.
1360 You can make both this and the C<weak_ref> option true.
1362 =item * trigger => $sub
1364 This option accepts a subroutine reference, which will be called after
1365 the attribute is set.
1367 =item * required => $bool
1369 An attribute which is required must be provided to the constructor. An
1370 attribute which is required can also have a C<default> or C<builder>,
1371 which will satisfy its required-ness.
1373 A required attribute must have a C<default>, C<builder> or a
1374 non-C<undef> C<init_arg>
1376 =item * lazy => $bool
1378 A lazy attribute must have a C<default> or C<builder>. When an
1379 attribute is lazy, the default value will not be calculated until the
1382 =item * weak_ref => $bool
1384 If this is true, the attribute's value will be stored as a weak
1387 =item * auto_deref => $bool
1389 If this is true, then the reader will dereference the value when it is
1390 called. The attribute must have a type constraint which defines the
1391 attribute as an array or hash reference.
1393 =item * lazy_build => $bool
1395 Setting this to true makes the attribute lazy and provides a number of
1403 is equivalent to this:
1408 builder => '_build_size',
1409 clearer => 'clear_size',
1410 predicate => 'has_size',
1414 If your attribute name starts with an underscore (C<_>), then the clearer
1415 and predicate will as well:
1427 builder => '_build__size',
1428 clearer => '_clear_size',
1429 predicate => '_has_size',
1432 Note the doubled underscore in the builder name. Internally, Moose
1433 simply prepends the attribute name with "_build_" to come up with the
1436 =item * documentation
1438 An arbitrary string that can be retrieved later by calling C<<
1439 $attr->documentation >>.
1443 =item B<< $attr->clone(%options) >>
1445 This creates a new attribute based on attribute being cloned. You must
1446 supply a C<name> option to provide a new name for the attribute.
1448 The C<%options> can only specify options handled by
1449 L<Class::MOP::Attribute>.
1453 =head2 Value management
1457 =item B<< $attr->initialize_instance_slot($meta_instance, $instance, $params) >>
1459 This method is used internally to initialize the attribute's slot in
1460 the object C<$instance>.
1462 This overrides the L<Class::MOP::Attribute> method to handle lazy
1463 attributes, weak references, and type constraints.
1469 eval { $point->meta->get_attribute('x')->set_value($point, 'forty-two') };
1474 I<Attribute (x) does not pass the type constraint (Int) with 'forty-two'>
1476 Before setting the value, a check is made on the type constraint of
1477 the attribute, if it has one, to see if the value passes it. If the
1478 value fails to pass, the set operation dies.
1480 Any coercion to convert values is done before checking the type constraint.
1482 To check a value against a type constraint before setting it, fetch the
1483 attribute instance using L<Class::MOP::Class/find_attribute_by_name>,
1484 fetch the type_constraint from the attribute using L<Moose::Meta::Attribute/type_constraint>
1485 and call L<Moose::Meta::TypeConstraint/check>. See L<Moose::Cookbook::Basics::Company_Subtypes>
1490 =head2 Attribute Accessor generation
1494 =item B<< $attr->install_accessors >>
1496 This method overrides the parent to also install delegation methods.
1498 If, after installing all methods, the attribute object has no associated
1499 methods, it throws an error unless C<< is => 'bare' >> was passed to the
1500 attribute constructor. (Trying to add an attribute that has no associated
1501 methods is almost always an error.)
1503 =item B<< $attr->remove_accessors >>
1505 This method overrides the parent to also remove delegation methods.
1507 =item B<< $attr->inline_set($instance_var, $value_var) >>
1509 This method return a code snippet suitable for inlining the relevant
1510 operation. It expect strings containing variable names to be used in the
1511 inlining, like C<'$self'> or C<'$_[1]'>.
1513 =item B<< $attr->install_delegation >>
1515 This method adds its delegation methods to the attribute's associated
1516 class, if it has any to add.
1518 =item B<< $attr->remove_delegation >>
1520 This method remove its delegation methods from the attribute's
1523 =item B<< $attr->accessor_metaclass >>
1525 Returns the accessor metaclass name, which defaults to
1526 L<Moose::Meta::Method::Accessor>.
1528 =item B<< $attr->delegation_metaclass >>
1530 Returns the delegation metaclass name, which defaults to
1531 L<Moose::Meta::Method::Delegation>.
1535 =head2 Additional Moose features
1537 These methods are not found in the superclass. They support features
1542 =item B<< $attr->does($role) >>
1544 This indicates whether the I<attribute itself> does the given
1545 role. The role can be given as a full class name, or as a resolvable
1548 Note that this checks the attribute itself, not its type constraint,
1549 so it is checking the attribute's metaclass and any traits applied to
1552 =item B<< Moose::Meta::Class->interpolate_class_and_new($name, %options) >>
1554 This is an alternate constructor that handles the C<metaclass> and
1557 Effectively, this method is a factory that finds or creates the
1558 appropriate class for the given C<metaclass> and/or C<traits>.
1560 Once it has the appropriate class, it will call C<< $class->new($name,
1561 %options) >> on that class.
1563 =item B<< $attr->clone_and_inherit_options(%options) >>
1565 This method supports the C<has '+foo'> feature. It does various bits
1566 of processing on the supplied C<%options> before ultimately calling
1567 the C<clone> method.
1569 One of its main tasks is to make sure that the C<%options> provided
1570 does not include the options returned by the
1571 C<illegal_options_for_inheritance> method.
1573 =item B<< $attr->illegal_options_for_inheritance >>
1575 This returns a blacklist of options that can not be overridden in a
1576 subclass's attribute definition.
1578 This exists to allow a custom metaclass to change or add to the list
1579 of options which can not be changed.
1581 =item B<< $attr->type_constraint >>
1583 Returns the L<Moose::Meta::TypeConstraint> object for this attribute,
1586 =item B<< $attr->has_type_constraint >>
1588 Returns true if this attribute has a type constraint.
1590 =item B<< $attr->verify_against_type_constraint($value) >>
1592 Given a value, this method returns true if the value is valid for the
1593 attribute's type constraint. If the value is not valid, it throws an
1596 =item B<< $attr->handles >>
1598 This returns the value of the C<handles> option passed to the
1601 =item B<< $attr->has_handles >>
1603 Returns true if this attribute performs delegation.
1605 =item B<< $attr->is_weak_ref >>
1607 Returns true if this attribute stores its value as a weak reference.
1609 =item B<< $attr->is_required >>
1611 Returns true if this attribute is required to have a value.
1613 =item B<< $attr->is_lazy >>
1615 Returns true if this attribute is lazy.
1617 =item B<< $attr->is_lazy_build >>
1619 Returns true if the C<lazy_build> option was true when passed to the
1622 =item B<< $attr->should_coerce >>
1624 Returns true if the C<coerce> option passed to the constructor was
1627 =item B<< $attr->should_auto_deref >>
1629 Returns true if the C<auto_deref> option passed to the constructor was
1632 =item B<< $attr->trigger >>
1634 This is the subroutine reference that was in the C<trigger> option
1635 passed to the constructor, if any.
1637 =item B<< $attr->has_trigger >>
1639 Returns true if this attribute has a trigger set.
1641 =item B<< $attr->documentation >>
1643 Returns the value that was in the C<documentation> option passed to
1644 the constructor, if any.
1646 =item B<< $attr->has_documentation >>
1648 Returns true if this attribute has any documentation.
1650 =item B<< $attr->applied_traits >>
1652 This returns an array reference of all the traits which were applied
1653 to this attribute. If none were applied, this returns C<undef>.
1655 =item B<< $attr->has_applied_traits >>
1657 Returns true if this attribute has any traits applied.
1663 See L<Moose/BUGS> for details on reporting bugs.