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, $value),
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);
831 if ( $self->should_auto_deref && ! $for_trigger ) {
833 my $type_constraint = $self->type_constraint;
835 if ($type_constraint->is_a_type_of('ArrayRef')) {
836 my $rv = $self->SUPER::get_value($instance);
837 return unless defined $rv;
838 return wantarray ? @{ $rv } : $rv;
840 elsif ($type_constraint->is_a_type_of('HashRef')) {
841 my $rv = $self->SUPER::get_value($instance);
842 return unless defined $rv;
843 return wantarray ? %{ $rv } : $rv;
846 $self->throw_error("Can not auto de-reference the type constraint '" . $type_constraint->name . "'", object => $instance, type_constraint => $type_constraint);
852 return $self->SUPER::get_value($instance);
856 sub _inline_get_value {
858 my ($instance, $tc, $coercion, $message) = @_;
860 my $slot_access = $self->_inline_instance_get($instance);
861 $tc ||= '$type_constraint';
862 $coercion ||= '$type_coercion';
863 $message ||= '$type_message';
866 $self->_inline_check_lazy($instance, $tc, $coercion, $message),
867 $self->_inline_return_auto_deref($slot_access),
871 sub _inline_check_lazy {
873 my ($instance, $tc, $coercion, $message) = @_;
875 return unless $self->is_lazy;
877 my $slot_exists = $self->_inline_instance_has($instance);
880 'if (!' . $slot_exists . ') {',
881 $self->_inline_init_from_default($instance, '$default', $tc, $coercion, $message, 'lazy'),
886 sub _inline_init_from_default {
888 my ($instance, $default, $tc, $coercion, $message, $for_lazy) = @_;
890 if (!($self->has_default || $self->has_builder)) {
892 'You cannot have a lazy attribute '
893 . '(' . $self->name . ') '
894 . 'without specifying a default value for it',
900 $self->_inline_generate_default($instance, $default),
901 # intentionally not using _inline_tc_code, since that can be overridden
902 # to do things like possibly only do member tc checks, which isn't
903 # appropriate for checking the result of a default
904 $self->has_type_constraint
905 ? ($self->_inline_check_coercion($default, $tc, $coercion, $for_lazy),
906 $self->_inline_check_constraint($default, $tc, $message, $for_lazy))
908 $self->_inline_init_slot($instance, $default),
912 sub _inline_generate_default {
914 my ($instance, $default) = @_;
916 if ($self->has_default) {
917 my $source = 'my ' . $default . ' = $attr_default';
918 $source .= '->(' . $instance . ')'
919 if $self->is_default_a_coderef;
920 return $source . ';';
922 elsif ($self->has_builder) {
923 my $builder = B::perlstring($self->builder);
924 my $builder_str = quotemeta($self->builder);
925 my $attr_name_str = quotemeta($self->name);
927 'my ' . $default . ';',
928 'if (my $builder = ' . $instance . '->can(' . $builder . ')) {',
929 $default . ' = ' . $instance . '->$builder;',
932 'my $class = ref(' . $instance . ') || ' . $instance . ';',
933 $self->_inline_throw_error(
934 '"$class does not support builder method '
935 . '\'' . $builder_str . '\' for attribute '
936 . '\'' . $attr_name_str . '\'"'
943 "Can't generate a default for " . $self->name
944 . " since no default or builder was specified"
949 sub _inline_init_slot {
951 my ($inv, $value) = @_;
953 if ($self->has_initializer) {
954 return '$attr->set_initial_value(' . $inv . ', ' . $value . ');';
957 return $self->_inline_instance_set($inv, $value) . ';';
961 sub _inline_return_auto_deref {
964 return 'return ' . $self->_auto_deref(@_) . ';';
969 my ($ref_value) = @_;
971 return $ref_value unless $self->should_auto_deref;
973 my $type_constraint = $self->type_constraint;
976 if ($type_constraint->is_a_type_of('ArrayRef')) {
979 elsif ($type_constraint->is_a_type_of('HashRef')) {
984 'Can not auto de-reference the type constraint \''
985 . $type_constraint->name
987 type_constraint => $type_constraint,
992 . '? ' . $sigil . '{ (' . $ref_value . ') || return } '
993 . ': (' . $ref_value . ')';
996 ## installing accessors
998 sub accessor_metaclass { 'Moose::Meta::Method::Accessor' }
1000 sub install_accessors {
1002 $self->SUPER::install_accessors(@_);
1003 $self->install_delegation if $self->has_handles;
1007 sub _check_associated_methods {
1010 @{ $self->associated_methods }
1011 || ($self->_is_metadata || '') eq 'bare'
1014 'Attribute (' . $self->name . ') of class '
1015 . $self->associated_class->name
1016 . ' has no associated methods'
1017 . ' (did you mean to provide an "is" argument?)'
1023 sub _process_accessors {
1025 my ($type, $accessor, $generate_as_inline_methods) = @_;
1027 $accessor = ( keys %$accessor )[0] if ( ref($accessor) || '' ) eq 'HASH';
1028 my $method = $self->associated_class->get_method($accessor);
1031 && $method->isa('Class::MOP::Method::Accessor')
1032 && $method->associated_attribute->name ne $self->name ) {
1034 my $other_attr_name = $method->associated_attribute->name;
1035 my $name = $self->name;
1038 "You are overwriting an accessor ($accessor) for the $other_attr_name attribute"
1039 . " with a new accessor method for the $name attribute" );
1044 && !$method->is_stub
1045 && !$method->isa('Class::MOP::Method::Accessor')
1046 && ( !$self->definition_context
1047 || $method->package_name eq $self->definition_context->{package} )
1051 "You are overwriting a locally defined method ($accessor) with "
1055 if ( !$self->associated_class->has_method($accessor)
1056 && $self->associated_class->has_package_symbol( '&' . $accessor ) ) {
1059 "You are overwriting a locally defined function ($accessor) with "
1063 $self->SUPER::_process_accessors(@_);
1066 sub remove_accessors {
1068 $self->SUPER::remove_accessors(@_);
1069 $self->remove_delegation if $self->has_handles;
1073 sub install_delegation {
1077 # Here we canonicalize the 'handles' option
1078 # this will sort out any details and always
1079 # return an hash of methods which we want
1080 # to delagate to, see that method for details
1081 my %handles = $self->_canonicalize_handles;
1084 # install the delegation ...
1085 my $associated_class = $self->associated_class;
1086 foreach my $handle (sort keys %handles) {
1087 my $method_to_call = $handles{$handle};
1088 my $class_name = $associated_class->name;
1089 my $name = "${class_name}::${handle}";
1091 if ( my $method = $associated_class->get_method($handle) ) {
1093 "You cannot overwrite a locally defined method ($handle) with a delegation",
1094 method_name => $handle
1095 ) unless $method->is_stub;
1099 # handles is not allowed to delegate
1100 # any of these methods, as they will
1101 # override the ones in your class, which
1102 # is almost certainly not what you want.
1104 # FIXME warn when $handle was explicitly specified, but not if the source is a regex or something
1105 #cluck("Not delegating method '$handle' because it is a core method") and
1106 next if $class_name->isa("Moose::Object") and $handle =~ /^BUILD|DEMOLISH$/ || Moose::Object->can($handle);
1108 my $method = $self->_make_delegation_method($handle, $method_to_call);
1110 $self->associated_class->add_method($method->name, $method);
1111 $self->associate_method($method);
1115 sub remove_delegation {
1117 my %handles = $self->_canonicalize_handles;
1118 my $associated_class = $self->associated_class;
1119 foreach my $handle (keys %handles) {
1120 next unless any { $handle eq $_ }
1122 @{ $self->associated_methods };
1123 $self->associated_class->remove_method($handle);
1127 # private methods to help delegation ...
1129 sub _canonicalize_handles {
1131 my $handles = $self->handles;
1132 if (my $handle_type = ref($handles)) {
1133 if ($handle_type eq 'HASH') {
1136 elsif ($handle_type eq 'ARRAY') {
1137 return map { $_ => $_ } @{$handles};
1139 elsif ($handle_type eq 'Regexp') {
1140 ($self->has_type_constraint)
1141 || $self->throw_error("Cannot delegate methods based on a Regexp without a type constraint (isa)", data => $handles);
1142 return map { ($_ => $_) }
1143 grep { /$handles/ } $self->_get_delegate_method_list;
1145 elsif ($handle_type eq 'CODE') {
1146 return $handles->($self, $self->_find_delegate_metaclass);
1148 elsif (blessed($handles) && $handles->isa('Moose::Meta::TypeConstraint::DuckType')) {
1149 return map { $_ => $_ } @{ $handles->methods };
1151 elsif (blessed($handles) && $handles->isa('Moose::Meta::TypeConstraint::Role')) {
1152 $handles = $handles->role;
1155 $self->throw_error("Unable to canonicalize the 'handles' option with $handles", data => $handles);
1159 load_class($handles);
1160 my $role_meta = Class::MOP::class_of($handles);
1162 (blessed $role_meta && $role_meta->isa('Moose::Meta::Role'))
1163 || $self->throw_error("Unable to canonicalize the 'handles' option with $handles because its metaclass is not a Moose::Meta::Role", data => $handles);
1165 return map { $_ => $_ }
1167 grep { !$_->isa('Class::MOP::Method::Meta') } (
1168 $role_meta->_get_local_methods,
1169 $role_meta->get_required_method_list,
1173 sub _get_delegate_method_list {
1175 my $meta = $self->_find_delegate_metaclass;
1176 if ($meta->isa('Class::MOP::Class')) {
1177 return map { $_->name } # NOTE: !never! delegate &meta
1178 grep { $_->package_name ne 'Moose::Object' && !$_->isa('Class::MOP::Method::Meta') }
1179 $meta->get_all_methods;
1181 elsif ($meta->isa('Moose::Meta::Role')) {
1182 return $meta->get_method_list;
1185 $self->throw_error("Unable to recognize the delegate metaclass '$meta'", data => $meta);
1189 sub _find_delegate_metaclass {
1191 if (my $class = $self->_isa_metadata) {
1192 unless ( is_class_loaded($class) ) {
1195 'The %s attribute is trying to delegate to a class which has not been loaded - %s',
1200 # we might be dealing with a non-Moose class,
1201 # and need to make our own metaclass. if there's
1202 # already a metaclass, it will be returned
1203 return Class::MOP::Class->initialize($class);
1205 elsif (my $role = $self->_does_metadata) {
1206 unless ( is_class_loaded($class) ) {
1209 'The %s attribute is trying to delegate to a role which has not been loaded - %s',
1215 return Class::MOP::class_of($role);
1218 $self->throw_error("Cannot find delegate metaclass for attribute " . $self->name);
1222 sub delegation_metaclass { 'Moose::Meta::Method::Delegation' }
1224 sub _make_delegation_method {
1225 my ( $self, $handle_name, $method_to_call ) = @_;
1227 my @curried_arguments;
1229 ($method_to_call, @curried_arguments) = @$method_to_call
1230 if 'ARRAY' eq ref($method_to_call);
1232 return $self->delegation_metaclass->new(
1233 name => $handle_name,
1234 package_name => $self->associated_class->name,
1236 delegate_to_method => $method_to_call,
1237 curried_arguments => \@curried_arguments,
1241 sub _coerce_and_verify {
1244 my $instance = shift;
1246 return $val unless $self->has_type_constraint;
1248 $val = $self->type_constraint->coerce($val)
1249 if $self->should_coerce && $self->type_constraint->has_coercion;
1251 $self->verify_against_type_constraint($val, instance => $instance);
1256 sub verify_against_type_constraint {
1260 return 1 if !$self->has_type_constraint;
1262 my $type_constraint = $self->type_constraint;
1264 $type_constraint->check($val)
1265 || $self->throw_error("Attribute ("
1267 . ") does not pass the type constraint because: "
1268 . $type_constraint->get_message($val), data => $val, @_);
1271 package Moose::Meta::Attribute::Custom::Moose;
1272 sub register_implementation { 'Moose::Meta::Attribute' }
1276 # ABSTRACT: The Moose attribute metaclass
1284 This class is a subclass of L<Class::MOP::Attribute> that provides
1285 additional Moose-specific functionality.
1287 To really understand this class, you will need to start with the
1288 L<Class::MOP::Attribute> documentation. This class can be understood
1289 as a set of additional features on top of the basic feature provided
1290 by that parent class.
1294 C<Moose::Meta::Attribute> is a subclass of L<Class::MOP::Attribute>.
1298 Many of the documented below override methods in
1299 L<Class::MOP::Attribute> and add Moose specific features.
1305 =item B<< Moose::Meta::Attribute->new(%options) >>
1307 This method overrides the L<Class::MOP::Attribute> constructor.
1309 Many of the options below are described in more detail in the
1310 L<Moose::Manual::Attributes> document.
1312 It adds the following options to the constructor:
1316 =item * is => 'ro', 'rw', 'bare'
1318 This provides a shorthand for specifying the C<reader>, C<writer>, or
1319 C<accessor> names. If the attribute is read-only ('ro') then it will
1320 have a C<reader> method with the same attribute as the name.
1322 If it is read-write ('rw') then it will have an C<accessor> method
1323 with the same name. If you provide an explicit C<writer> for a
1324 read-write attribute, then you will have a C<reader> with the same
1325 name as the attribute, and a C<writer> with the name you provided.
1327 Use 'bare' when you are deliberately not installing any methods
1328 (accessor, reader, etc.) associated with this attribute; otherwise,
1329 Moose will issue a deprecation warning when this attribute is added to a
1332 =item * isa => $type
1334 This option accepts a type. The type can be a string, which should be
1335 a type name. If the type name is unknown, it is assumed to be a class
1338 This option can also accept a L<Moose::Meta::TypeConstraint> object.
1340 If you I<also> provide a C<does> option, then your C<isa> option must
1341 be a class name, and that class must do the role specified with
1344 =item * does => $role
1346 This is short-hand for saying that the attribute's type must be an
1347 object which does the named role.
1349 =item * coerce => $bool
1351 This option is only valid for objects with a type constraint
1352 (C<isa>) that defined a coercion. If this is true, then coercions will be applied whenever
1353 this attribute is set.
1355 You can make both this and the C<weak_ref> option true.
1357 =item * trigger => $sub
1359 This option accepts a subroutine reference, which will be called after
1360 the attribute is set.
1362 =item * required => $bool
1364 An attribute which is required must be provided to the constructor. An
1365 attribute which is required can also have a C<default> or C<builder>,
1366 which will satisfy its required-ness.
1368 A required attribute must have a C<default>, C<builder> or a
1369 non-C<undef> C<init_arg>
1371 =item * lazy => $bool
1373 A lazy attribute must have a C<default> or C<builder>. When an
1374 attribute is lazy, the default value will not be calculated until the
1377 =item * weak_ref => $bool
1379 If this is true, the attribute's value will be stored as a weak
1382 =item * auto_deref => $bool
1384 If this is true, then the reader will dereference the value when it is
1385 called. The attribute must have a type constraint which defines the
1386 attribute as an array or hash reference.
1388 =item * lazy_build => $bool
1390 Setting this to true makes the attribute lazy and provides a number of
1398 is equivalent to this:
1403 builder => '_build_size',
1404 clearer => 'clear_size',
1405 predicate => 'has_size',
1409 If your attribute name starts with an underscore (C<_>), then the clearer
1410 and predicate will as well:
1422 builder => '_build__size',
1423 clearer => '_clear_size',
1424 predicate => '_has_size',
1427 Note the doubled underscore in the builder name. Internally, Moose
1428 simply prepends the attribute name with "_build_" to come up with the
1431 =item * documentation
1433 An arbitrary string that can be retrieved later by calling C<<
1434 $attr->documentation >>.
1438 =item B<< $attr->clone(%options) >>
1440 This creates a new attribute based on attribute being cloned. You must
1441 supply a C<name> option to provide a new name for the attribute.
1443 The C<%options> can only specify options handled by
1444 L<Class::MOP::Attribute>.
1448 =head2 Value management
1452 =item B<< $attr->initialize_instance_slot($meta_instance, $instance, $params) >>
1454 This method is used internally to initialize the attribute's slot in
1455 the object C<$instance>.
1457 This overrides the L<Class::MOP::Attribute> method to handle lazy
1458 attributes, weak references, and type constraints.
1464 eval { $point->meta->get_attribute('x')->set_value($point, 'forty-two') };
1469 I<Attribute (x) does not pass the type constraint (Int) with 'forty-two'>
1471 Before setting the value, a check is made on the type constraint of
1472 the attribute, if it has one, to see if the value passes it. If the
1473 value fails to pass, the set operation dies with a L</throw_error>.
1475 Any coercion to convert values is done before checking the type constraint.
1477 To check a value against a type constraint before setting it, fetch the
1478 attribute instance using L<Class::MOP::Class/find_attribute_by_name>,
1479 fetch the type_constraint from the attribute using L<Moose::Meta::Attribute/type_constraint>
1480 and call L<Moose::Meta::TypeConstraint/check>. See L<Moose::Cookbook::Basics::Recipe4>
1485 =head2 Attribute Accessor generation
1489 =item B<< $attr->install_accessors >>
1491 This method overrides the parent to also install delegation methods.
1493 If, after installing all methods, the attribute object has no associated
1494 methods, it throws an error unless C<< is => 'bare' >> was passed to the
1495 attribute constructor. (Trying to add an attribute that has no associated
1496 methods is almost always an error.)
1498 =item B<< $attr->remove_accessors >>
1500 This method overrides the parent to also remove delegation methods.
1502 =item B<< $attr->inline_set($instance_var, $value_var) >>
1504 This method return a code snippet suitable for inlining the relevant
1505 operation. It expect strings containing variable names to be used in the
1506 inlining, like C<'$self'> or C<'$_[1]'>.
1508 =item B<< $attr->install_delegation >>
1510 This method adds its delegation methods to the attribute's associated
1511 class, if it has any to add.
1513 =item B<< $attr->remove_delegation >>
1515 This method remove its delegation methods from the attribute's
1518 =item B<< $attr->accessor_metaclass >>
1520 Returns the accessor metaclass name, which defaults to
1521 L<Moose::Meta::Method::Accessor>.
1523 =item B<< $attr->delegation_metaclass >>
1525 Returns the delegation metaclass name, which defaults to
1526 L<Moose::Meta::Method::Delegation>.
1530 =head2 Additional Moose features
1532 These methods are not found in the superclass. They support features
1537 =item B<< $attr->does($role) >>
1539 This indicates whether the I<attribute itself> does the given
1540 role. The role can be given as a full class name, or as a resolvable
1543 Note that this checks the attribute itself, not its type constraint,
1544 so it is checking the attribute's metaclass and any traits applied to
1547 =item B<< Moose::Meta::Class->interpolate_class_and_new($name, %options) >>
1549 This is an alternate constructor that handles the C<metaclass> and
1552 Effectively, this method is a factory that finds or creates the
1553 appropriate class for the given C<metaclass> and/or C<traits>.
1555 Once it has the appropriate class, it will call C<< $class->new($name,
1556 %options) >> on that class.
1558 =item B<< $attr->clone_and_inherit_options(%options) >>
1560 This method supports the C<has '+foo'> feature. It does various bits
1561 of processing on the supplied C<%options> before ultimately calling
1562 the C<clone> method.
1564 One of its main tasks is to make sure that the C<%options> provided
1565 does not include the options returned by the
1566 C<illegal_options_for_inheritance> method.
1568 =item B<< $attr->illegal_options_for_inheritance >>
1570 This returns a blacklist of options that can not be overridden in a
1571 subclass's attribute definition.
1573 This exists to allow a custom metaclass to change or add to the list
1574 of options which can not be changed.
1576 =item B<< $attr->type_constraint >>
1578 Returns the L<Moose::Meta::TypeConstraint> object for this attribute,
1581 =item B<< $attr->has_type_constraint >>
1583 Returns true if this attribute has a type constraint.
1585 =item B<< $attr->verify_against_type_constraint($value) >>
1587 Given a value, this method returns true if the value is valid for the
1588 attribute's type constraint. If the value is not valid, it throws an
1591 =item B<< $attr->handles >>
1593 This returns the value of the C<handles> option passed to the
1596 =item B<< $attr->has_handles >>
1598 Returns true if this attribute performs delegation.
1600 =item B<< $attr->is_weak_ref >>
1602 Returns true if this attribute stores its value as a weak reference.
1604 =item B<< $attr->is_required >>
1606 Returns true if this attribute is required to have a value.
1608 =item B<< $attr->is_lazy >>
1610 Returns true if this attribute is lazy.
1612 =item B<< $attr->is_lazy_build >>
1614 Returns true if the C<lazy_build> option was true when passed to the
1617 =item B<< $attr->should_coerce >>
1619 Returns true if the C<coerce> option passed to the constructor was
1622 =item B<< $attr->should_auto_deref >>
1624 Returns true if the C<auto_deref> option passed to the constructor was
1627 =item B<< $attr->trigger >>
1629 This is the subroutine reference that was in the C<trigger> option
1630 passed to the constructor, if any.
1632 =item B<< $attr->has_trigger >>
1634 Returns true if this attribute has a trigger set.
1636 =item B<< $attr->documentation >>
1638 Returns the value that was in the C<documentation> option passed to
1639 the constructor, if any.
1641 =item B<< $attr->has_documentation >>
1643 Returns true if this attribute has any documentation.
1645 =item B<< $attr->applied_traits >>
1647 This returns an array reference of all the traits which were applied
1648 to this attribute. If none were applied, this returns C<undef>.
1650 =item B<< $attr->has_applied_traits >>
1652 Returns true if this attribute has any traits applied.
1658 See L<Moose/BUGS> for details on reporting bugs.