2 package Moose::Meta::Attribute;
9 use Scalar::Util 'blessed', 'weaken';
10 use List::MoreUtils 'any';
14 use Moose::Deprecated;
15 use Moose::Meta::Method::Accessor;
16 use Moose::Meta::Method::Delegation;
18 use Moose::Util::TypeConstraints ();
19 use Class::MOP::MiniTrait;
21 use base 'Class::MOP::Attribute', 'Moose::Meta::Mixin::AttributeCore';
23 Class::MOP::MiniTrait::apply(__PACKAGE__, 'Moose::Meta::Object::Trait');
25 __PACKAGE__->meta->add_attribute('traits' => (
26 reader => 'applied_traits',
27 predicate => 'has_applied_traits',
28 Class::MOP::_definition_context(),
31 # we need to have a ->does method in here to
32 # more easily support traits, and the introspection
33 # of those traits. We extend the does check to look
34 # for metatrait aliases.
36 my ($self, $role_name) = @_;
38 Moose::Util::resolve_metatrait_alias(Attribute => $role_name)
40 return 0 if !defined($name); # failed to load class
41 return $self->Moose::Object::does($name);
46 require Moose::Meta::Class;
47 ( ref $self && $self->associated_class ) || "Moose::Meta::Class";
52 my $inv = $self->_error_thrower;
53 unshift @_, "message" if @_ % 2 == 1;
54 unshift @_, attr => $self if ref $self;
56 my $handler = $inv->can("throw_error"); # to avoid incrementing depth by 1
60 sub _inline_throw_error {
61 my ( $self, $msg, $args ) = @_;
63 my $inv = $self->_error_thrower;
65 $inv = 'Moose::Meta::Class' unless $inv->can('_inline_throw_error');
68 my $class = $self->associated_class;
70 my $class_name = B::perlstring($class->name);
71 my $attr_name = B::perlstring($self->name);
72 $args = 'attr => Class::MOP::class_of(' . $class_name . ')'
73 . '->find_attribute_by_name(' . $attr_name . '), '
74 . (defined $args ? $args : '');
77 return $inv->_inline_throw_error($msg, $args)
81 my ($class, $name, %options) = @_;
82 $class->_process_options($name, \%options) unless $options{__hack_no_process_options}; # used from clone()... YECHKKK FIXME ICKY YUCK GROSS
84 delete $options{__hack_no_process_options};
89 map { $_->init_arg() }
90 $class->meta()->get_all_attributes()
93 my @bad = sort grep { ! $attrs{$_} } keys %options;
97 Carp::cluck "Found unknown argument(s) passed to '$name' attribute constructor in '$class': @bad";
100 return $class->SUPER::new($name, %options);
103 sub interpolate_class_and_new {
104 my ($class, $name, %args) = @_;
106 my ( $new_class, @traits ) = $class->interpolate_class(\%args);
108 $new_class->new($name, %args, ( scalar(@traits) ? ( traits => \@traits ) : () ) );
111 sub interpolate_class {
112 my ($class, $options) = @_;
114 $class = ref($class) || $class;
116 if ( my $metaclass_name = delete $options->{metaclass} ) {
117 my $new_class = Moose::Util::resolve_metaclass_alias( Attribute => $metaclass_name );
119 if ( $class ne $new_class ) {
120 if ( $new_class->can("interpolate_class") ) {
121 return $new_class->interpolate_class($options);
130 if (my $traits = $options->{traits}) {
132 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});
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});
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(
369 sub _process_does_option {
370 my ( $class, $name, $options ) = @_;
372 return unless exists $options->{does} && ! exists $options->{isa};
374 # allow for anon-subtypes here ...
375 if ( blessed( $options->{does} )
376 && $options->{does}->isa('Moose::Meta::TypeConstraint') ) {
377 $options->{type_constraint} = $options->{does};
380 $options->{type_constraint}
381 = Moose::Util::TypeConstraints::find_or_create_does_type_constraint(
386 sub _process_coerce_option {
387 my ( $class, $name, $options ) = @_;
389 return unless $options->{coerce};
391 ( exists $options->{type_constraint} )
392 || $class->throw_error(
393 "You cannot have coercion without specifying a type constraint on attribute ($name)",
397 "You cannot have a weak reference to a coerced value on attribute ($name)",
399 if $options->{weak_ref};
401 unless ( $options->{type_constraint}->has_coercion ) {
402 my $type = $options->{type_constraint}->name;
404 Moose::Deprecated::deprecated(
405 feature => 'coerce without coercion',
407 "You cannot coerce an attribute ($name) unless its type ($type) has a coercion"
412 sub _process_trigger_option {
413 my ( $class, $name, $options ) = @_;
415 return unless exists $options->{trigger};
417 ( 'CODE' eq ref $options->{trigger} )
418 || $class->throw_error("Trigger must be a CODE ref on attribute ($name)", data => $options->{trigger});
421 sub _process_auto_deref_option {
422 my ( $class, $name, $options ) = @_;
424 return unless $options->{auto_deref};
426 ( exists $options->{type_constraint} )
427 || $class->throw_error(
428 "You cannot auto-dereference without specifying a type constraint on attribute ($name)",
431 ( $options->{type_constraint}->is_a_type_of('ArrayRef')
432 || $options->{type_constraint}->is_a_type_of('HashRef') )
433 || $class->throw_error(
434 "You cannot auto-dereference anything other than a ArrayRef or HashRef on attribute ($name)",
438 sub _process_lazy_build_option {
439 my ( $class, $name, $options ) = @_;
441 return unless $options->{lazy_build};
444 "You can not use lazy_build and default for the same attribute ($name)",
446 if exists $options->{default};
448 $options->{lazy} = 1;
449 $options->{builder} ||= "_build_${name}";
451 if ( $name =~ /^_/ ) {
452 $options->{clearer} ||= "_clear${name}";
453 $options->{predicate} ||= "_has${name}";
456 $options->{clearer} ||= "clear_${name}";
457 $options->{predicate} ||= "has_${name}";
461 sub _process_lazy_option {
462 my ( $class, $name, $options ) = @_;
464 return unless $options->{lazy};
466 ( exists $options->{default} || defined $options->{builder} )
467 || $class->throw_error(
468 "You cannot have a lazy attribute ($name) without specifying a default value for it",
472 sub _process_required_option {
473 my ( $class, $name, $options ) = @_;
478 ( !exists $options->{init_arg} || defined $options->{init_arg} )
479 || exists $options->{default}
480 || defined $options->{builder}
484 "You cannot have a required attribute ($name) without a default, builder, or an init_arg",
489 sub initialize_instance_slot {
490 my ($self, $meta_instance, $instance, $params) = @_;
491 my $init_arg = $self->init_arg();
492 # try to fetch the init arg from the %params ...
496 if ( defined($init_arg) and exists $params->{$init_arg}) {
497 $val = $params->{$init_arg};
501 # skip it if it's lazy
502 return if $self->is_lazy;
503 # and die if it's required and doesn't have a default value
504 $self->throw_error("Attribute (" . $self->name . ") is required", object => $instance, data => $params)
505 if $self->is_required && !$self->has_default && !$self->has_builder;
507 # if nothing was in the %params, we can use the
508 # attribute's default value (if it has one)
509 if ($self->has_default) {
510 $val = $self->default($instance);
513 elsif ($self->has_builder) {
514 $val = $self->_call_builder($instance);
519 return unless $value_is_set;
521 $val = $self->_coerce_and_verify( $val, $instance );
523 $self->set_initial_value($instance, $val);
525 if ( ref $val && $self->is_weak_ref ) {
526 $self->_weaken_value($instance);
531 my ( $self, $instance ) = @_;
533 my $builder = $self->builder();
535 return $instance->$builder()
536 if $instance->can( $self->builder );
538 $self->throw_error( blessed($instance)
539 . " does not support builder method '"
541 . "' for attribute '"
550 sub _make_initializer_writer_callback {
552 my ($meta_instance, $instance, $slot_name) = @_;
553 my $old_callback = $self->SUPER::_make_initializer_writer_callback(@_);
555 $old_callback->($self->_coerce_and_verify($_[0], $instance));
560 my ($self, $instance, @args) = @_;
561 my $value = $args[0];
563 my $attr_name = quotemeta($self->name);
565 if ($self->is_required and not @args) {
566 $self->throw_error("Attribute ($attr_name) is required", object => $instance);
569 $value = $self->_coerce_and_verify( $value, $instance );
572 if ( $self->has_trigger && $self->has_value($instance) ) {
573 @old = $self->get_value($instance, 'for trigger');
576 $self->SUPER::set_value($instance, $value);
578 if ( ref $value && $self->is_weak_ref ) {
579 $self->_weaken_value($instance);
582 if ($self->has_trigger) {
583 $self->trigger->($instance, $value, @old);
587 sub _inline_set_value {
589 my ($instance, $value, $tc, $coercion, $message, $for_constructor) = @_;
593 $tc ||= '$type_constraint';
594 $coercion ||= '$type_coercion';
595 $message ||= '$type_message';
598 if ($self->_writer_value_needs_copy) {
599 push @code, $self->_inline_copy_value($value, $copy);
603 # constructors already handle required checks
604 push @code, $self->_inline_check_required
605 unless $for_constructor;
607 push @code, $self->_inline_tc_code($value, $tc, $coercion, $message);
609 # constructors do triggers all at once at the end
610 push @code, $self->_inline_get_old_value_for_trigger($instance, $old)
611 unless $for_constructor;
614 $self->SUPER::_inline_set_value($instance, $value),
615 $self->_inline_weaken_value($instance, $value),
618 # constructors do triggers all at once at the end
619 push @code, $self->_inline_trigger($instance, $value, $old)
620 unless $for_constructor;
625 sub _writer_value_needs_copy {
627 return $self->should_coerce;
630 sub _inline_copy_value {
632 my ($value, $copy) = @_;
634 return 'my ' . $copy . ' = ' . $value . ';'
637 sub _inline_check_required {
640 return unless $self->is_required;
642 my $attr_name = quotemeta($self->name);
646 $self->_inline_throw_error(
647 '"Attribute (' . $attr_name . ') is required, so cannot '
648 . 'be set to undef"' # defined $_[1] is not good enough
654 sub _inline_tc_code {
656 my ($value, $tc, $coercion, $message, $is_lazy) = @_;
658 $self->_inline_check_coercion(
659 $value, $tc, $coercion, $is_lazy,
661 $self->_inline_check_constraint(
662 $value, $tc, $message, $is_lazy,
667 sub _inline_check_coercion {
669 my ($value, $tc, $coercion) = @_;
671 return unless $self->should_coerce && $self->type_constraint->has_coercion;
673 if ( $self->type_constraint->can_be_inlined ) {
675 'if (! (' . $self->type_constraint->_inline_check($value) . ')) {',
676 $value . ' = ' . $coercion . '->(' . $value . ');',
682 'if (!' . $tc . '->(' . $value . ')) {',
683 $value . ' = ' . $coercion . '->(' . $value . ');',
689 sub _inline_check_constraint {
691 my ($value, $tc, $message) = @_;
693 return unless $self->has_type_constraint;
695 my $attr_name = quotemeta($self->name);
697 if ( $self->type_constraint->can_be_inlined ) {
699 'if (! (' . $self->type_constraint->_inline_check($value) . ')) {',
700 $self->_inline_throw_error(
701 '"Attribute (' . $attr_name . ') does not pass the type '
702 . 'constraint because: " . '
703 . 'do { local $_ = ' . $value . '; '
704 . $message . '->(' . $value . ')'
713 'if (!' . $tc . '->(' . $value . ')) {',
714 $self->_inline_throw_error(
715 '"Attribute (' . $attr_name . ') does not pass the type '
716 . 'constraint because: " . '
717 . 'do { local $_ = ' . $value . '; '
718 . $message . '->(' . $value . ')'
727 sub _inline_get_old_value_for_trigger {
729 my ($instance, $old) = @_;
731 return unless $self->has_trigger;
734 'my ' . $old . ' = ' . $self->_inline_instance_has($instance),
735 '? ' . $self->_inline_instance_get($instance),
740 sub _inline_weaken_value {
742 my ($instance, $value) = @_;
744 return unless $self->is_weak_ref;
746 my $mi = $self->associated_class->get_meta_instance;
748 $mi->inline_weaken_slot_value($instance, $self->name, $value),
749 'if ref ' . $value . ';',
753 sub _inline_trigger {
755 my ($instance, $value, $old) = @_;
757 return unless $self->has_trigger;
759 return '$trigger->(' . $instance . ', ' . $value . ', ' . $old . ');';
762 sub _eval_environment {
767 $env->{'$trigger'} = \($self->trigger)
768 if $self->has_trigger;
769 $env->{'$attr_default'} = \($self->default)
770 if $self->has_default;
772 if ($self->has_type_constraint) {
773 my $tc_obj = $self->type_constraint;
775 $env->{'$type_constraint'} = \(
776 $tc_obj->_compiled_type_constraint
777 ) unless $tc_obj->can_be_inlined;
778 # these two could probably get inlined versions too
779 $env->{'$type_coercion'} = \(
780 $tc_obj->coercion->_compiled_type_coercion
781 ) if $tc_obj->has_coercion;
782 $env->{'$type_message'} = \(
783 $tc_obj->has_message ? $tc_obj->message : $tc_obj->_default_message
786 $env = { %$env, %{ $tc_obj->inline_environment } };
790 $env->{'$attr'} = \$self
791 if $self->has_initializer && $self->is_lazy;
792 # pretty sure this is only going to be closed over if you use a custom
793 # error class at this point, but we should still get rid of this
795 $env->{'$meta'} = \($self->associated_class);
801 my ( $self, $instance ) = @_;
803 my $meta_instance = Class::MOP::Class->initialize( blessed($instance) )
806 $meta_instance->weaken_slot_value( $instance, $self->name );
810 my ($self, $instance, $for_trigger) = @_;
812 if ($self->is_lazy) {
813 unless ($self->has_value($instance)) {
815 if ($self->has_default) {
816 $value = $self->default($instance);
817 } elsif ( $self->has_builder ) {
818 $value = $self->_call_builder($instance);
821 $value = $self->_coerce_and_verify( $value, $instance );
823 $self->set_initial_value($instance, $value);
827 if ( $self->should_auto_deref && ! $for_trigger ) {
829 my $type_constraint = $self->type_constraint;
831 if ($type_constraint->is_a_type_of('ArrayRef')) {
832 my $rv = $self->SUPER::get_value($instance);
833 return unless defined $rv;
834 return wantarray ? @{ $rv } : $rv;
836 elsif ($type_constraint->is_a_type_of('HashRef')) {
837 my $rv = $self->SUPER::get_value($instance);
838 return unless defined $rv;
839 return wantarray ? %{ $rv } : $rv;
842 $self->throw_error("Can not auto de-reference the type constraint '" . $type_constraint->name . "'", object => $instance, type_constraint => $type_constraint);
848 return $self->SUPER::get_value($instance);
852 sub _inline_get_value {
854 my ($instance, $tc, $coercion, $message) = @_;
856 my $slot_access = $self->_inline_instance_get($instance);
857 $tc ||= '$type_constraint';
858 $coercion ||= '$type_coercion';
859 $message ||= '$type_message';
862 $self->_inline_check_lazy($instance, $tc, $coercion, $message),
863 $self->_inline_return_auto_deref($slot_access),
867 sub _inline_check_lazy {
869 my ($instance, $tc, $coercion, $message) = @_;
871 return unless $self->is_lazy;
873 my $slot_exists = $self->_inline_instance_has($instance);
876 'if (!' . $slot_exists . ') {',
877 $self->_inline_init_from_default($instance, '$default', $tc, $coercion, $message, 'lazy'),
882 sub _inline_init_from_default {
884 my ($instance, $default, $tc, $coercion, $message, $for_lazy) = @_;
886 if (!($self->has_default || $self->has_builder)) {
888 'You cannot have a lazy attribute '
889 . '(' . $self->name . ') '
890 . 'without specifying a default value for it',
896 $self->_inline_generate_default($instance, $default),
897 # intentionally not using _inline_tc_code, since that can be overridden
898 # to do things like possibly only do member tc checks, which isn't
899 # appropriate for checking the result of a default
900 $self->has_type_constraint
901 ? ($self->_inline_check_coercion($default, $tc, $coercion, $for_lazy),
902 $self->_inline_check_constraint($default, $tc, $message, $for_lazy))
904 $self->_inline_init_slot($instance, $default),
908 sub _inline_generate_default {
910 my ($instance, $default) = @_;
912 if ($self->has_default) {
913 my $source = 'my ' . $default . ' = $attr_default';
914 $source .= '->(' . $instance . ')'
915 if $self->is_default_a_coderef;
916 return $source . ';';
918 elsif ($self->has_builder) {
919 my $builder = B::perlstring($self->builder);
920 my $builder_str = quotemeta($self->builder);
921 my $attr_name_str = quotemeta($self->name);
923 'my ' . $default . ';',
924 'if (my $builder = ' . $instance . '->can(' . $builder . ')) {',
925 $default . ' = ' . $instance . '->$builder;',
928 'my $class = ref(' . $instance . ') || ' . $instance . ';',
929 $self->_inline_throw_error(
930 '"$class does not support builder method '
931 . '\'' . $builder_str . '\' for attribute '
932 . '\'' . $attr_name_str . '\'"'
939 "Can't generate a default for " . $self->name
940 . " since no default or builder was specified"
945 sub _inline_init_slot {
947 my ($inv, $value) = @_;
949 if ($self->has_initializer) {
950 return '$attr->set_initial_value(' . $inv . ', ' . $value . ');';
953 return $self->_inline_instance_set($inv, $value) . ';';
957 sub _inline_return_auto_deref {
960 return 'return ' . $self->_auto_deref(@_) . ';';
965 my ($ref_value) = @_;
967 return $ref_value unless $self->should_auto_deref;
969 my $type_constraint = $self->type_constraint;
972 if ($type_constraint->is_a_type_of('ArrayRef')) {
975 elsif ($type_constraint->is_a_type_of('HashRef')) {
980 'Can not auto de-reference the type constraint \''
981 . $type_constraint->name
983 type_constraint => $type_constraint,
988 . '? ' . $sigil . '{ (' . $ref_value . ') || return } '
989 . ': (' . $ref_value . ')';
992 ## installing accessors
994 sub accessor_metaclass { 'Moose::Meta::Method::Accessor' }
996 sub install_accessors {
998 $self->SUPER::install_accessors(@_);
999 $self->install_delegation if $self->has_handles;
1003 sub _check_associated_methods {
1006 @{ $self->associated_methods }
1007 || ($self->_is_metadata || '') eq 'bare'
1010 'Attribute (' . $self->name . ') of class '
1011 . $self->associated_class->name
1012 . ' has no associated methods'
1013 . ' (did you mean to provide an "is" argument?)'
1019 sub _process_accessors {
1021 my ($type, $accessor, $generate_as_inline_methods) = @_;
1023 $accessor = ( keys %$accessor )[0] if ( ref($accessor) || '' ) eq 'HASH';
1024 my $method = $self->associated_class->get_method($accessor);
1027 && $method->isa('Class::MOP::Method::Accessor')
1028 && $method->associated_attribute->name ne $self->name ) {
1030 my $other_attr_name = $method->associated_attribute->name;
1031 my $name = $self->name;
1034 "You are overwriting an accessor ($accessor) for the $other_attr_name attribute"
1035 . " with a new accessor method for the $name attribute" );
1040 && !$method->isa('Class::MOP::Method::Accessor')
1041 && ( !$self->definition_context
1042 || $method->package_name eq $self->definition_context->{package} )
1046 "You are overwriting a locally defined method ($accessor) with "
1050 if ( !$self->associated_class->has_method($accessor)
1051 && $self->associated_class->has_package_symbol( '&' . $accessor ) ) {
1054 "You are overwriting a locally defined function ($accessor) with "
1058 $self->SUPER::_process_accessors(@_);
1061 sub remove_accessors {
1063 $self->SUPER::remove_accessors(@_);
1064 $self->remove_delegation if $self->has_handles;
1068 sub install_delegation {
1072 # Here we canonicalize the 'handles' option
1073 # this will sort out any details and always
1074 # return an hash of methods which we want
1075 # to delagate to, see that method for details
1076 my %handles = $self->_canonicalize_handles;
1079 # install the delegation ...
1080 my $associated_class = $self->associated_class;
1081 foreach my $handle (sort keys %handles) {
1082 my $method_to_call = $handles{$handle};
1083 my $class_name = $associated_class->name;
1084 my $name = "${class_name}::${handle}";
1086 (!$associated_class->has_method($handle))
1087 || $self->throw_error("You cannot overwrite a locally defined method ($handle) with a delegation", method_name => $handle);
1090 # handles is not allowed to delegate
1091 # any of these methods, as they will
1092 # override the ones in your class, which
1093 # is almost certainly not what you want.
1095 # FIXME warn when $handle was explicitly specified, but not if the source is a regex or something
1096 #cluck("Not delegating method '$handle' because it is a core method") and
1097 next if $class_name->isa("Moose::Object") and $handle =~ /^BUILD|DEMOLISH$/ || Moose::Object->can($handle);
1099 my $method = $self->_make_delegation_method($handle, $method_to_call);
1101 $self->associated_class->add_method($method->name, $method);
1102 $self->associate_method($method);
1106 sub remove_delegation {
1108 my %handles = $self->_canonicalize_handles;
1109 my $associated_class = $self->associated_class;
1110 foreach my $handle (keys %handles) {
1111 next unless any { $handle eq $_ }
1113 @{ $self->associated_methods };
1114 $self->associated_class->remove_method($handle);
1118 # private methods to help delegation ...
1120 sub _canonicalize_handles {
1122 my $handles = $self->handles;
1123 if (my $handle_type = ref($handles)) {
1124 if ($handle_type eq 'HASH') {
1127 elsif ($handle_type eq 'ARRAY') {
1128 return map { $_ => $_ } @{$handles};
1130 elsif ($handle_type eq 'Regexp') {
1131 ($self->has_type_constraint)
1132 || $self->throw_error("Cannot delegate methods based on a Regexp without a type constraint (isa)", data => $handles);
1133 return map { ($_ => $_) }
1134 grep { /$handles/ } $self->_get_delegate_method_list;
1136 elsif ($handle_type eq 'CODE') {
1137 return $handles->($self, $self->_find_delegate_metaclass);
1139 elsif (blessed($handles) && $handles->isa('Moose::Meta::TypeConstraint::DuckType')) {
1140 return map { $_ => $_ } @{ $handles->methods };
1142 elsif (blessed($handles) && $handles->isa('Moose::Meta::TypeConstraint::Role')) {
1143 $handles = $handles->role;
1146 $self->throw_error("Unable to canonicalize the 'handles' option with $handles", data => $handles);
1150 Class::MOP::load_class($handles);
1151 my $role_meta = Class::MOP::class_of($handles);
1153 (blessed $role_meta && $role_meta->isa('Moose::Meta::Role'))
1154 || $self->throw_error("Unable to canonicalize the 'handles' option with $handles because its metaclass is not a Moose::Meta::Role", data => $handles);
1156 return map { $_ => $_ }
1158 grep { !$_->isa('Class::MOP::Method::Meta') } (
1159 $role_meta->_get_local_methods,
1160 $role_meta->get_required_method_list,
1164 sub _get_delegate_method_list {
1166 my $meta = $self->_find_delegate_metaclass;
1167 if ($meta->isa('Class::MOP::Class')) {
1168 return map { $_->name } # NOTE: !never! delegate &meta
1169 grep { $_->package_name ne 'Moose::Object' && !$_->isa('Class::MOP::Method::Meta') }
1170 $meta->get_all_methods;
1172 elsif ($meta->isa('Moose::Meta::Role')) {
1173 return $meta->get_method_list;
1176 $self->throw_error("Unable to recognize the delegate metaclass '$meta'", data => $meta);
1180 sub _find_delegate_metaclass {
1182 if (my $class = $self->_isa_metadata) {
1183 unless ( Class::MOP::is_class_loaded($class) ) {
1186 'The %s attribute is trying to delegate to a class which has not been loaded - %s',
1191 # we might be dealing with a non-Moose class,
1192 # and need to make our own metaclass. if there's
1193 # already a metaclass, it will be returned
1194 return Class::MOP::Class->initialize($class);
1196 elsif (my $role = $self->_does_metadata) {
1197 unless ( Class::MOP::is_class_loaded($class) ) {
1200 'The %s attribute is trying to delegate to a role which has not been loaded - %s',
1206 return Class::MOP::class_of($role);
1209 $self->throw_error("Cannot find delegate metaclass for attribute " . $self->name);
1213 sub delegation_metaclass { 'Moose::Meta::Method::Delegation' }
1215 sub _make_delegation_method {
1216 my ( $self, $handle_name, $method_to_call ) = @_;
1218 my @curried_arguments;
1220 ($method_to_call, @curried_arguments) = @$method_to_call
1221 if 'ARRAY' eq ref($method_to_call);
1223 return $self->delegation_metaclass->new(
1224 name => $handle_name,
1225 package_name => $self->associated_class->name,
1227 delegate_to_method => $method_to_call,
1228 curried_arguments => \@curried_arguments,
1232 sub _coerce_and_verify {
1235 my $instance = shift;
1237 return $val unless $self->has_type_constraint;
1239 $val = $self->type_constraint->coerce($val)
1240 if $self->should_coerce && $self->type_constraint->has_coercion;
1242 $self->verify_against_type_constraint($val, instance => $instance);
1247 sub verify_against_type_constraint {
1251 return 1 if !$self->has_type_constraint;
1253 my $type_constraint = $self->type_constraint;
1255 $type_constraint->check($val)
1256 || $self->throw_error("Attribute ("
1258 . ") does not pass the type constraint because: "
1259 . $type_constraint->get_message($val), data => $val, @_);
1262 package Moose::Meta::Attribute::Custom::Moose;
1263 sub register_implementation { 'Moose::Meta::Attribute' }
1267 # ABSTRACT: The Moose attribute metaclass
1275 This class is a subclass of L<Class::MOP::Attribute> that provides
1276 additional Moose-specific functionality.
1278 To really understand this class, you will need to start with the
1279 L<Class::MOP::Attribute> documentation. This class can be understood
1280 as a set of additional features on top of the basic feature provided
1281 by that parent class.
1285 C<Moose::Meta::Attribute> is a subclass of L<Class::MOP::Attribute>.
1289 Many of the documented below override methods in
1290 L<Class::MOP::Attribute> and add Moose specific features.
1296 =item B<< Moose::Meta::Attribute->new(%options) >>
1298 This method overrides the L<Class::MOP::Attribute> constructor.
1300 Many of the options below are described in more detail in the
1301 L<Moose::Manual::Attributes> document.
1303 It adds the following options to the constructor:
1307 =item * is => 'ro', 'rw', 'bare'
1309 This provides a shorthand for specifying the C<reader>, C<writer>, or
1310 C<accessor> names. If the attribute is read-only ('ro') then it will
1311 have a C<reader> method with the same attribute as the name.
1313 If it is read-write ('rw') then it will have an C<accessor> method
1314 with the same name. If you provide an explicit C<writer> for a
1315 read-write attribute, then you will have a C<reader> with the same
1316 name as the attribute, and a C<writer> with the name you provided.
1318 Use 'bare' when you are deliberately not installing any methods
1319 (accessor, reader, etc.) associated with this attribute; otherwise,
1320 Moose will issue a deprecation warning when this attribute is added to a
1323 =item * isa => $type
1325 This option accepts a type. The type can be a string, which should be
1326 a type name. If the type name is unknown, it is assumed to be a class
1329 This option can also accept a L<Moose::Meta::TypeConstraint> object.
1331 If you I<also> provide a C<does> option, then your C<isa> option must
1332 be a class name, and that class must do the role specified with
1335 =item * does => $role
1337 This is short-hand for saying that the attribute's type must be an
1338 object which does the named role.
1340 =item * coerce => $bool
1342 This option is only valid for objects with a type constraint
1343 (C<isa>) that defined a coercion. If this is true, then coercions will be applied whenever
1344 this attribute is set.
1346 You can make both this and the C<weak_ref> option true.
1348 =item * trigger => $sub
1350 This option accepts a subroutine reference, which will be called after
1351 the attribute is set.
1353 =item * required => $bool
1355 An attribute which is required must be provided to the constructor. An
1356 attribute which is required can also have a C<default> or C<builder>,
1357 which will satisfy its required-ness.
1359 A required attribute must have a C<default>, C<builder> or a
1360 non-C<undef> C<init_arg>
1362 =item * lazy => $bool
1364 A lazy attribute must have a C<default> or C<builder>. When an
1365 attribute is lazy, the default value will not be calculated until the
1368 =item * weak_ref => $bool
1370 If this is true, the attribute's value will be stored as a weak
1373 =item * auto_deref => $bool
1375 If this is true, then the reader will dereference the value when it is
1376 called. The attribute must have a type constraint which defines the
1377 attribute as an array or hash reference.
1379 =item * lazy_build => $bool
1381 Setting this to true makes the attribute lazy and provides a number of
1389 is equivalent to this:
1394 builder => '_build_size',
1395 clearer => 'clear_size',
1396 predicate => 'has_size',
1400 If your attribute name starts with an underscore (C<_>), then the clearer
1401 and predicate will as well:
1413 builder => '_build__size',
1414 clearer => '_clear_size',
1415 predicate => '_has_size',
1418 Note the doubled underscore in the builder name. Internally, Moose
1419 simply prepends the attribute name with "_build_" to come up with the
1422 =item * documentation
1424 An arbitrary string that can be retrieved later by calling C<<
1425 $attr->documentation >>.
1429 =item B<< $attr->clone(%options) >>
1431 This creates a new attribute based on attribute being cloned. You must
1432 supply a C<name> option to provide a new name for the attribute.
1434 The C<%options> can only specify options handled by
1435 L<Class::MOP::Attribute>.
1439 =head2 Value management
1443 =item B<< $attr->initialize_instance_slot($meta_instance, $instance, $params) >>
1445 This method is used internally to initialize the attribute's slot in
1446 the object C<$instance>.
1448 This overrides the L<Class::MOP::Attribute> method to handle lazy
1449 attributes, weak references, and type constraints.
1455 eval { $point->meta->get_attribute('x')->set_value($point, 'forty-two') };
1460 I<Attribute (x) does not pass the type constraint (Int) with 'forty-two'>
1462 Before setting the value, a check is made on the type constraint of
1463 the attribute, if it has one, to see if the value passes it. If the
1464 value fails to pass, the set operation dies with a L</throw_error>.
1466 Any coercion to convert values is done before checking the type constraint.
1468 To check a value against a type constraint before setting it, fetch the
1469 attribute instance using L<Class::MOP::Class/find_attribute_by_name>,
1470 fetch the type_constraint from the attribute using L<Moose::Meta::Attribute/type_constraint>
1471 and call L<Moose::Meta::TypeConstraint/check>. See L<Moose::Cookbook::Basics::Recipe4>
1476 =head2 Attribute Accessor generation
1480 =item B<< $attr->install_accessors >>
1482 This method overrides the parent to also install delegation methods.
1484 If, after installing all methods, the attribute object has no associated
1485 methods, it throws an error unless C<< is => 'bare' >> was passed to the
1486 attribute constructor. (Trying to add an attribute that has no associated
1487 methods is almost always an error.)
1489 =item B<< $attr->remove_accessors >>
1491 This method overrides the parent to also remove delegation methods.
1493 =item B<< $attr->inline_set($instance_var, $value_var) >>
1495 This method return a code snippet suitable for inlining the relevant
1496 operation. It expect strings containing variable names to be used in the
1497 inlining, like C<'$self'> or C<'$_[1]'>.
1499 =item B<< $attr->install_delegation >>
1501 This method adds its delegation methods to the attribute's associated
1502 class, if it has any to add.
1504 =item B<< $attr->remove_delegation >>
1506 This method remove its delegation methods from the attribute's
1509 =item B<< $attr->accessor_metaclass >>
1511 Returns the accessor metaclass name, which defaults to
1512 L<Moose::Meta::Method::Accessor>.
1514 =item B<< $attr->delegation_metaclass >>
1516 Returns the delegation metaclass name, which defaults to
1517 L<Moose::Meta::Method::Delegation>.
1521 =head2 Additional Moose features
1523 These methods are not found in the superclass. They support features
1528 =item B<< $attr->does($role) >>
1530 This indicates whether the I<attribute itself> does the given
1531 role. The role can be given as a full class name, or as a resolvable
1534 Note that this checks the attribute itself, not its type constraint,
1535 so it is checking the attribute's metaclass and any traits applied to
1538 =item B<< Moose::Meta::Class->interpolate_class_and_new($name, %options) >>
1540 This is an alternate constructor that handles the C<metaclass> and
1543 Effectively, this method is a factory that finds or creates the
1544 appropriate class for the given C<metaclass> and/or C<traits>.
1546 Once it has the appropriate class, it will call C<< $class->new($name,
1547 %options) >> on that class.
1549 =item B<< $attr->clone_and_inherit_options(%options) >>
1551 This method supports the C<has '+foo'> feature. It does various bits
1552 of processing on the supplied C<%options> before ultimately calling
1553 the C<clone> method.
1555 One of its main tasks is to make sure that the C<%options> provided
1556 does not include the options returned by the
1557 C<illegal_options_for_inheritance> method.
1559 =item B<< $attr->illegal_options_for_inheritance >>
1561 This returns a blacklist of options that can not be overridden in a
1562 subclass's attribute definition.
1564 This exists to allow a custom metaclass to change or add to the list
1565 of options which can not be changed.
1567 =item B<< $attr->type_constraint >>
1569 Returns the L<Moose::Meta::TypeConstraint> object for this attribute,
1572 =item B<< $attr->has_type_constraint >>
1574 Returns true if this attribute has a type constraint.
1576 =item B<< $attr->verify_against_type_constraint($value) >>
1578 Given a value, this method returns true if the value is valid for the
1579 attribute's type constraint. If the value is not valid, it throws an
1582 =item B<< $attr->handles >>
1584 This returns the value of the C<handles> option passed to the
1587 =item B<< $attr->has_handles >>
1589 Returns true if this attribute performs delegation.
1591 =item B<< $attr->is_weak_ref >>
1593 Returns true if this attribute stores its value as a weak reference.
1595 =item B<< $attr->is_required >>
1597 Returns true if this attribute is required to have a value.
1599 =item B<< $attr->is_lazy >>
1601 Returns true if this attribute is lazy.
1603 =item B<< $attr->is_lazy_build >>
1605 Returns true if the C<lazy_build> option was true when passed to the
1608 =item B<< $attr->should_coerce >>
1610 Returns true if the C<coerce> option passed to the constructor was
1613 =item B<< $attr->should_auto_deref >>
1615 Returns true if the C<auto_deref> option passed to the constructor was
1618 =item B<< $attr->trigger >>
1620 This is the subroutine reference that was in the C<trigger> option
1621 passed to the constructor, if any.
1623 =item B<< $attr->has_trigger >>
1625 Returns true if this attribute has a trigger set.
1627 =item B<< $attr->documentation >>
1629 Returns the value that was in the C<documentation> option passed to
1630 the constructor, if any.
1632 =item B<< $attr->has_documentation >>
1634 Returns true if this attribute has any documentation.
1636 =item B<< $attr->applied_traits >>
1638 This returns an array reference of all the traits which were applied
1639 to this attribute. If none were applied, this returns C<undef>.
1641 =item B<< $attr->has_applied_traits >>
1643 Returns true if this attribute has any traits applied.
1649 See L<Moose/BUGS> for details on reporting bugs.