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',
30 # we need to have a ->does method in here to
31 # more easily support traits, and the introspection
32 # of those traits. We extend the does check to look
33 # for metatrait aliases.
35 my ($self, $role_name) = @_;
37 Moose::Util::resolve_metatrait_alias(Attribute => $role_name)
39 return 0 if !defined($name); # failed to load class
40 return $self->Moose::Object::does($name);
45 my $class = ( ref $self && $self->associated_class ) || "Moose::Meta::Class";
46 unshift @_, "message" if @_ % 2 == 1;
47 unshift @_, attr => $self if ref $self;
49 my $handler = $class->can("throw_error"); # to avoid incrementing depth by 1
53 sub _inline_throw_error {
54 my ( $self, $msg, $args ) = @_;
55 "\$meta->throw_error($msg" . ($args ? ", $args" : "") . ")"; # FIXME makes deparsing *REALLY* hard
59 my ($class, $name, %options) = @_;
60 $class->_process_options($name, \%options) unless $options{__hack_no_process_options}; # used from clone()... YECHKKK FIXME ICKY YUCK GROSS
62 delete $options{__hack_no_process_options};
67 map { $_->init_arg() }
68 $class->meta()->get_all_attributes()
71 my @bad = sort grep { ! $attrs{$_} } keys %options;
75 Carp::cluck "Found unknown argument(s) passed to '$name' attribute constructor in '$class': @bad";
78 return $class->SUPER::new($name, %options);
81 sub interpolate_class_and_new {
82 my ($class, $name, %args) = @_;
84 my ( $new_class, @traits ) = $class->interpolate_class(\%args);
86 $new_class->new($name, %args, ( scalar(@traits) ? ( traits => \@traits ) : () ) );
89 sub interpolate_class {
90 my ($class, $options) = @_;
92 $class = ref($class) || $class;
94 if ( my $metaclass_name = delete $options->{metaclass} ) {
95 my $new_class = Moose::Util::resolve_metaclass_alias( Attribute => $metaclass_name );
97 if ( $class ne $new_class ) {
98 if ( $new_class->can("interpolate_class") ) {
99 return $new_class->interpolate_class($options);
108 if (my $traits = $options->{traits}) {
110 while ($i < @$traits) {
111 my $trait = $traits->[$i++];
112 next if ref($trait); # options to a trait we discarded
114 $trait = Moose::Util::resolve_metatrait_alias(Attribute => $trait)
117 next if $class->does($trait);
119 push @traits, $trait;
122 push @traits, $traits->[$i++]
123 if $traits->[$i] && ref($traits->[$i]);
127 my $anon_class = Moose::Meta::Class->create_anon_class(
128 superclasses => [ $class ],
129 roles => [ @traits ],
133 $class = $anon_class->name;
137 return ( wantarray ? ( $class, @traits ) : $class );
142 # method-generating options shouldn't be overridden
143 sub illegal_options_for_inheritance {
144 qw(reader writer accessor clearer predicate)
148 # This method *must* be able to handle
149 # Class::MOP::Attribute instances as
150 # well. Yes, I know that is wrong, but
151 # apparently we didn't realize it was
152 # doing that and now we have some code
153 # which is dependent on it. The real
154 # solution of course is to push this
155 # feature back up into Class::MOP::Attribute
156 # but I not right now, I am too lazy.
157 # However if you are reading this and
158 # looking for something to do,.. please
161 sub clone_and_inherit_options {
162 my ($self, %options) = @_;
165 # we may want to extends a Class::MOP::Attribute
166 # in which case we need to be able to use the
167 # core set of legal options that have always
168 # been here. But we allows Moose::Meta::Attribute
169 # instances to changes them.
171 my @illegal_options = $self->can('illegal_options_for_inheritance')
172 ? $self->illegal_options_for_inheritance
175 my @found_illegal_options = grep { exists $options{$_} && exists $self->{$_} ? $_ : undef } @illegal_options;
176 (scalar @found_illegal_options == 0)
177 || $self->throw_error("Illegal inherited options => (" . (join ', ' => @found_illegal_options) . ")", data => \%options);
181 if (blessed($options{isa}) && $options{isa}->isa('Moose::Meta::TypeConstraint')) {
182 $type_constraint = $options{isa};
185 $type_constraint = Moose::Util::TypeConstraints::find_or_create_isa_type_constraint($options{isa});
186 (defined $type_constraint)
187 || $self->throw_error("Could not find the type constraint '" . $options{isa} . "'", data => $options{isa});
190 $options{type_constraint} = $type_constraint;
193 if ($options{does}) {
195 if (blessed($options{does}) && $options{does}->isa('Moose::Meta::TypeConstraint')) {
196 $type_constraint = $options{does};
199 $type_constraint = Moose::Util::TypeConstraints::find_or_create_does_type_constraint($options{does});
200 (defined $type_constraint)
201 || $self->throw_error("Could not find the type constraint '" . $options{does} . "'", data => $options{does});
204 $options{type_constraint} = $type_constraint;
208 # this doesn't apply to Class::MOP::Attributes,
209 # so we can ignore it for them.
211 if ($self->can('interpolate_class')) {
212 ( $options{metaclass}, my @traits ) = $self->interpolate_class(\%options);
215 my @all_traits = grep { $seen{$_}++ } @{ $self->applied_traits || [] }, @traits;
216 $options{traits} = \@all_traits if @all_traits;
219 # This method can be called on a CMOP::Attribute object, so we need to
220 # make sure we can call this method.
221 $self->_process_lazy_build_option( $self->name, \%options )
222 if $self->can('_process_lazy_build_option');
224 $self->clone(%options);
228 my ( $self, %params ) = @_;
230 my $class = delete $params{metaclass} || ref $self;
232 my ( @init, @non_init );
234 foreach my $attr ( grep { $_->has_value($self) } Class::MOP::class_of($self)->get_all_attributes ) {
235 push @{ $attr->has_init_arg ? \@init : \@non_init }, $attr;
238 my %new_params = ( ( map { $_->init_arg => $_->get_value($self) } @init ), %params );
240 my $name = delete $new_params{name};
242 my $clone = $class->new($name, %new_params, __hack_no_process_options => 1 );
244 foreach my $attr ( @non_init ) {
245 $attr->set_value($clone, $attr->get_value($self));
251 sub _process_options {
252 my ( $class, $name, $options ) = @_;
254 $class->_process_is_option( $name, $options );
255 $class->_process_isa_option( $name, $options );
256 $class->_process_does_option( $name, $options );
257 $class->_process_coerce_option( $name, $options );
258 $class->_process_trigger_option( $name, $options );
259 $class->_process_auto_deref_option( $name, $options );
260 $class->_process_lazy_build_option( $name, $options );
261 $class->_process_lazy_option( $name, $options );
262 $class->_process_required_option( $name, $options );
265 sub _process_is_option {
266 my ( $class, $name, $options ) = @_;
268 return unless $options->{is};
270 ### -------------------------
271 ## is => ro, writer => _foo # turns into (reader => foo, writer => _foo) as before
272 ## is => rw, writer => _foo # turns into (reader => foo, writer => _foo)
273 ## is => rw, accessor => _foo # turns into (accessor => _foo)
274 ## is => ro, accessor => _foo # error, accesor is rw
275 ### -------------------------
277 if ( $options->{is} eq 'ro' ) {
279 "Cannot define an accessor name on a read-only attribute, accessors are read/write",
281 if exists $options->{accessor};
282 $options->{reader} ||= $name;
284 elsif ( $options->{is} eq 'rw' ) {
285 if ( $options->{writer} ) {
286 $options->{reader} ||= $name;
289 $options->{accessor} ||= $name;
292 elsif ( $options->{is} eq 'bare' ) {
294 # do nothing, but don't complain (later) about missing methods
297 $class->throw_error( "I do not understand this option (is => "
299 . ") on attribute ($name)", data => $options->{is} );
303 sub _process_isa_option {
304 my ( $class, $name, $options ) = @_;
306 return unless exists $options->{isa};
308 if ( exists $options->{does} ) {
309 if ( try { $options->{isa}->can('does') } ) {
310 ( $options->{isa}->does( $options->{does} ) )
311 || $class->throw_error(
312 "Cannot have an isa option and a does option if the isa does not do the does on attribute ($name)",
317 "Cannot have an isa option which cannot ->does() on attribute ($name)",
322 # allow for anon-subtypes here ...
323 if ( blessed( $options->{isa} )
324 && $options->{isa}->isa('Moose::Meta::TypeConstraint') ) {
325 $options->{type_constraint} = $options->{isa};
328 $options->{type_constraint}
329 = Moose::Util::TypeConstraints::find_or_create_isa_type_constraint(
334 sub _process_does_option {
335 my ( $class, $name, $options ) = @_;
337 return unless exists $options->{does} && ! exists $options->{isa};
339 # allow for anon-subtypes here ...
340 if ( blessed( $options->{does} )
341 && $options->{does}->isa('Moose::Meta::TypeConstraint') ) {
342 $options->{type_constraint} = $options->{does};
345 $options->{type_constraint}
346 = Moose::Util::TypeConstraints::find_or_create_does_type_constraint(
351 sub _process_coerce_option {
352 my ( $class, $name, $options ) = @_;
354 return unless $options->{coerce};
356 ( exists $options->{type_constraint} )
357 || $class->throw_error(
358 "You cannot have coercion without specifying a type constraint on attribute ($name)",
362 "You cannot have a weak reference to a coerced value on attribute ($name)",
364 if $options->{weak_ref};
366 unless ( $options->{type_constraint}->has_coercion ) {
367 my $type = $options->{type_constraint}->name;
369 Moose::Deprecated::deprecated(
370 feature => 'coerce without coercion',
372 "You cannot coerce an attribute ($name) unless its type ($type) has a coercion"
377 sub _process_trigger_option {
378 my ( $class, $name, $options ) = @_;
380 return unless exists $options->{trigger};
382 ( 'CODE' eq ref $options->{trigger} )
383 || $class->throw_error("Trigger must be a CODE ref on attribute ($name)", data => $options->{trigger});
386 sub _process_auto_deref_option {
387 my ( $class, $name, $options ) = @_;
389 return unless $options->{auto_deref};
391 ( exists $options->{type_constraint} )
392 || $class->throw_error(
393 "You cannot auto-dereference without specifying a type constraint on attribute ($name)",
396 ( $options->{type_constraint}->is_a_type_of('ArrayRef')
397 || $options->{type_constraint}->is_a_type_of('HashRef') )
398 || $class->throw_error(
399 "You cannot auto-dereference anything other than a ArrayRef or HashRef on attribute ($name)",
403 sub _process_lazy_build_option {
404 my ( $class, $name, $options ) = @_;
406 return unless $options->{lazy_build};
409 "You can not use lazy_build and default for the same attribute ($name)",
411 if exists $options->{default};
413 $options->{lazy} = 1;
414 $options->{builder} ||= "_build_${name}";
416 if ( $name =~ /^_/ ) {
417 $options->{clearer} ||= "_clear${name}";
418 $options->{predicate} ||= "_has${name}";
421 $options->{clearer} ||= "clear_${name}";
422 $options->{predicate} ||= "has_${name}";
426 sub _process_lazy_option {
427 my ( $class, $name, $options ) = @_;
429 return unless $options->{lazy};
431 ( exists $options->{default} || defined $options->{builder} )
432 || $class->throw_error(
433 "You cannot have a lazy attribute ($name) without specifying a default value for it",
437 sub _process_required_option {
438 my ( $class, $name, $options ) = @_;
443 ( !exists $options->{init_arg} || defined $options->{init_arg} )
444 || exists $options->{default}
445 || defined $options->{builder}
449 "You cannot have a required attribute ($name) without a default, builder, or an init_arg",
454 sub initialize_instance_slot {
455 my ($self, $meta_instance, $instance, $params) = @_;
456 my $init_arg = $self->init_arg();
457 # try to fetch the init arg from the %params ...
461 if ( defined($init_arg) and exists $params->{$init_arg}) {
462 $val = $params->{$init_arg};
466 # skip it if it's lazy
467 return if $self->is_lazy;
468 # and die if it's required and doesn't have a default value
469 $self->throw_error("Attribute (" . $self->name . ") is required", object => $instance, data => $params)
470 if $self->is_required && !$self->has_default && !$self->has_builder;
472 # if nothing was in the %params, we can use the
473 # attribute's default value (if it has one)
474 if ($self->has_default) {
475 $val = $self->default($instance);
478 elsif ($self->has_builder) {
479 $val = $self->_call_builder($instance);
484 return unless $value_is_set;
486 $val = $self->_coerce_and_verify( $val, $instance );
488 $self->set_initial_value($instance, $val);
490 if ( ref $val && $self->is_weak_ref ) {
491 $self->_weaken_value($instance);
496 my ( $self, $instance ) = @_;
498 my $builder = $self->builder();
500 return $instance->$builder()
501 if $instance->can( $self->builder );
503 $self->throw_error( blessed($instance)
504 . " does not support builder method '"
506 . "' for attribute '"
515 sub _make_initializer_writer_callback {
517 my ($meta_instance, $instance, $slot_name) = @_;
518 my $old_callback = $self->SUPER::_make_initializer_writer_callback(@_);
520 $old_callback->($self->_coerce_and_verify($_[0], $instance));
525 my ($self, $instance, @args) = @_;
526 my $value = $args[0];
528 my $attr_name = quotemeta($self->name);
530 if ($self->is_required and not @args) {
531 $self->throw_error("Attribute ($attr_name) is required", object => $instance);
534 $value = $self->_coerce_and_verify( $value, $instance );
537 if ( $self->has_trigger && $self->has_value($instance) ) {
538 @old = $self->get_value($instance, 'for trigger');
541 $self->SUPER::set_value($instance, $value);
543 if ( ref $value && $self->is_weak_ref ) {
544 $self->_weaken_value($instance);
547 if ($self->has_trigger) {
548 $self->trigger->($instance, $value, @old);
552 sub _inline_set_value {
554 my ($instance, $value, $tc, $tc_obj, $for_constructor) = @_;
558 $tc ||= '$type_constraint';
559 $tc_obj ||= '$type_constraint_obj';
562 if ($self->_writer_value_needs_copy) {
563 push @code, $self->_inline_copy_value($value, $copy);
567 # constructors already handle required checks
568 push @code, $self->_inline_check_required
569 unless $for_constructor;
571 push @code, $self->_inline_tc_code($value, $tc, $tc_obj);
573 # constructors do triggers all at once at the end
574 push @code, $self->_inline_get_old_value_for_trigger($instance, $old)
575 unless $for_constructor;
578 $self->SUPER::_inline_set_value($instance, $value),
579 $self->_inline_weaken_value($instance, $value),
582 # constructors do triggers all at once at the end
583 push @code, $self->_inline_trigger($instance, $value, $old)
584 unless $for_constructor;
589 sub _writer_value_needs_copy {
591 return $self->should_coerce;
594 sub _inline_copy_value {
596 my ($value, $copy) = @_;
598 return 'my ' . $copy . ' = ' . $value . ';'
601 sub _inline_check_required {
604 return unless $self->is_required;
606 my $attr_name = quotemeta($self->name);
610 $self->_inline_throw_error(
611 '"Attribute (' . $attr_name . ') is required, so cannot '
612 . 'be set to undef"' # defined $_[1] is not good enough
618 sub _inline_tc_code {
621 $self->_inline_check_coercion(@_),
622 $self->_inline_check_constraint(@_),
626 sub _inline_check_coercion {
628 my ($value, $tc, $tc_obj) = @_;
630 return unless $self->should_coerce && $self->type_constraint->has_coercion;
632 return $value . ' = ' . $tc_obj . '->coerce(' . $value . ');';
635 sub _inline_check_constraint {
637 my ($value, $tc, $tc_obj) = @_;
639 return unless $self->has_type_constraint;
641 my $attr_name = quotemeta($self->name);
643 if ( $self->type_constraint->can_be_inlined ) {
645 'if (! (' . $self->type_constraint->_inline_check($value) . ')) {',
646 $self->_inline_throw_error(
647 '"Attribute (' . $attr_name . ') does not pass the type '
648 . 'constraint because: " . '
649 . $tc_obj . '->get_message(' . $value . ')',
657 'if (!' . $tc . '->(' . $value . ')) {',
658 $self->_inline_throw_error(
659 '"Attribute (' . $attr_name . ') does not pass the type '
660 . 'constraint because: " . '
661 . $tc_obj . '->get_message(' . $value . ')',
669 sub _inline_get_old_value_for_trigger {
671 my ($instance, $old) = @_;
673 return unless $self->has_trigger;
676 'my ' . $old . ' = ' . $self->_inline_instance_has($instance),
677 '? ' . $self->_inline_instance_get($instance),
682 sub _inline_weaken_value {
684 my ($instance, $value) = @_;
686 return unless $self->is_weak_ref;
688 my $mi = $self->associated_class->get_meta_instance;
690 $mi->inline_weaken_slot_value($instance, $self->name, $value),
691 'if ref ' . $value . ';',
695 sub _inline_trigger {
697 my ($instance, $value, $old) = @_;
699 return unless $self->has_trigger;
701 return '$trigger->(' . $instance . ', ' . $value . ', ' . $old . ');';
705 my ( $self, $instance ) = @_;
707 my $meta_instance = Class::MOP::Class->initialize( blessed($instance) )
710 $meta_instance->weaken_slot_value( $instance, $self->name );
714 my ($self, $instance, $for_trigger) = @_;
716 if ($self->is_lazy) {
717 unless ($self->has_value($instance)) {
719 if ($self->has_default) {
720 $value = $self->default($instance);
721 } elsif ( $self->has_builder ) {
722 $value = $self->_call_builder($instance);
725 $value = $self->_coerce_and_verify( $value, $instance );
727 $self->set_initial_value($instance, $value);
731 if ( $self->should_auto_deref && ! $for_trigger ) {
733 my $type_constraint = $self->type_constraint;
735 if ($type_constraint->is_a_type_of('ArrayRef')) {
736 my $rv = $self->SUPER::get_value($instance);
737 return unless defined $rv;
738 return wantarray ? @{ $rv } : $rv;
740 elsif ($type_constraint->is_a_type_of('HashRef')) {
741 my $rv = $self->SUPER::get_value($instance);
742 return unless defined $rv;
743 return wantarray ? %{ $rv } : $rv;
746 $self->throw_error("Can not auto de-reference the type constraint '" . $type_constraint->name . "'", object => $instance, type_constraint => $type_constraint);
752 return $self->SUPER::get_value($instance);
756 sub _inline_get_value {
758 my ($instance, $tc, $tc_obj) = @_;
760 my $slot_access = $self->_inline_instance_get($instance);
761 $tc ||= '$type_constraint';
762 $tc_obj ||= '$type_constraint_obj';
765 $self->_inline_check_lazy($instance, $tc, $tc_obj),
766 $self->_inline_return_auto_deref($slot_access),
770 sub _inline_check_lazy {
772 my ($instance, $tc, $tc_obj) = @_;
774 return unless $self->is_lazy;
776 my $slot_exists = $self->_inline_instance_has($instance);
779 'if (!' . $slot_exists . ') {',
780 $self->_inline_init_from_default($instance, '$default', $tc, $tc_obj, 'lazy'),
785 sub _inline_init_from_default {
787 my ($instance, $default, $tc, $tc_obj, $for_lazy) = @_;
789 if (!($self->has_default || $self->has_builder)) {
791 'You cannot have a lazy attribute '
792 . '(' . $self->name . ') '
793 . 'without specifying a default value for it',
799 $self->_inline_generate_default($instance, $default),
800 # intentionally not using _inline_tc_code, since that can be overridden
801 # to do things like possibly only do member tc checks, which isn't
802 # appropriate for checking the result of a default
803 $self->has_type_constraint
804 ? ($self->_inline_check_coercion($default, $tc, $tc_obj, $for_lazy),
805 $self->_inline_check_constraint($default, $tc, $tc_obj, $for_lazy))
807 $self->_inline_init_slot($instance, $default),
811 sub _inline_generate_default {
813 my ($instance, $default) = @_;
815 if ($self->has_default) {
816 my $source = 'my ' . $default . ' = $default';
817 $source .= '->(' . $instance . ')'
818 if $self->is_default_a_coderef;
819 return $source . ';';
821 elsif ($self->has_builder) {
822 my $builder = B::perlstring($self->builder);
823 my $builder_str = quotemeta($self->builder);
824 my $attr_name_str = quotemeta($self->name);
826 'my ' . $default . ';',
827 'if (my $builder = ' . $instance . '->can(' . $builder . ')) {',
828 $default . ' = ' . $instance . '->$builder;',
831 'my $class = ref(' . $instance . ') || ' . $instance . ';',
832 $self->_inline_throw_error(
833 '"$class does not support builder method '
834 . '\'' . $builder_str . '\' for attribute '
835 . '\'' . $attr_name_str . '\'"'
842 "Can't generate a default for " . $self->name
843 . " since no default or builder was specified"
848 sub _inline_init_slot {
850 my ($inv, $value) = @_;
852 if ($self->has_initializer) {
853 return '$attr->set_initial_value(' . $inv . ', ' . $value . ');';
856 return $self->_inline_instance_set($inv, $value) . ';';
860 sub _inline_return_auto_deref {
863 return 'return ' . $self->_auto_deref(@_) . ';';
868 my ($ref_value) = @_;
870 return $ref_value unless $self->should_auto_deref;
872 my $type_constraint = $self->type_constraint;
875 if ($type_constraint->is_a_type_of('ArrayRef')) {
878 elsif ($type_constraint->is_a_type_of('HashRef')) {
883 'Can not auto de-reference the type constraint \''
884 . $type_constraint->name
886 type_constraint => $type_constraint,
891 . '? ' . $sigil . '{ (' . $ref_value . ') || return } '
892 . ': (' . $ref_value . ')';
895 ## installing accessors
897 sub accessor_metaclass { 'Moose::Meta::Method::Accessor' }
899 sub install_accessors {
901 $self->SUPER::install_accessors(@_);
902 $self->install_delegation if $self->has_handles;
906 sub _check_associated_methods {
909 @{ $self->associated_methods }
910 || ($self->_is_metadata || '') eq 'bare'
913 'Attribute (' . $self->name . ') of class '
914 . $self->associated_class->name
915 . ' has no associated methods'
916 . ' (did you mean to provide an "is" argument?)'
922 sub _process_accessors {
924 my ($type, $accessor, $generate_as_inline_methods) = @_;
926 $accessor = ( keys %$accessor )[0] if ( ref($accessor) || '' ) eq 'HASH';
927 my $method = $self->associated_class->get_method($accessor);
930 && $method->isa('Class::MOP::Method::Accessor')
931 && $method->associated_attribute->name ne $self->name ) {
933 my $other_attr_name = $method->associated_attribute->name;
934 my $name = $self->name;
937 "You are overwriting an accessor ($accessor) for the $other_attr_name attribute"
938 . " with a new accessor method for the $name attribute" );
943 && !$method->isa('Class::MOP::Method::Accessor')
944 && ( !$self->definition_context
945 || $method->package_name eq $self->definition_context->{package} )
949 "You are overwriting a locally defined method ($accessor) with "
953 if ( !$self->associated_class->has_method($accessor)
954 && $self->associated_class->has_package_symbol( '&' . $accessor ) ) {
957 "You are overwriting a locally defined function ($accessor) with "
961 $self->SUPER::_process_accessors(@_);
964 sub remove_accessors {
966 $self->SUPER::remove_accessors(@_);
967 $self->remove_delegation if $self->has_handles;
971 sub install_delegation {
975 # Here we canonicalize the 'handles' option
976 # this will sort out any details and always
977 # return an hash of methods which we want
978 # to delagate to, see that method for details
979 my %handles = $self->_canonicalize_handles;
982 # install the delegation ...
983 my $associated_class = $self->associated_class;
984 foreach my $handle (keys %handles) {
985 my $method_to_call = $handles{$handle};
986 my $class_name = $associated_class->name;
987 my $name = "${class_name}::${handle}";
989 (!$associated_class->has_method($handle))
990 || $self->throw_error("You cannot overwrite a locally defined method ($handle) with a delegation", method_name => $handle);
993 # handles is not allowed to delegate
994 # any of these methods, as they will
995 # override the ones in your class, which
996 # is almost certainly not what you want.
998 # FIXME warn when $handle was explicitly specified, but not if the source is a regex or something
999 #cluck("Not delegating method '$handle' because it is a core method") and
1000 next if $class_name->isa("Moose::Object") and $handle =~ /^BUILD|DEMOLISH$/ || Moose::Object->can($handle);
1002 my $method = $self->_make_delegation_method($handle, $method_to_call);
1004 $self->associated_class->add_method($method->name, $method);
1005 $self->associate_method($method);
1009 sub remove_delegation {
1011 my %handles = $self->_canonicalize_handles;
1012 my $associated_class = $self->associated_class;
1013 foreach my $handle (keys %handles) {
1014 next unless any { $handle eq $_ }
1016 @{ $self->associated_methods };
1017 $self->associated_class->remove_method($handle);
1021 # private methods to help delegation ...
1023 sub _canonicalize_handles {
1025 my $handles = $self->handles;
1026 if (my $handle_type = ref($handles)) {
1027 if ($handle_type eq 'HASH') {
1030 elsif ($handle_type eq 'ARRAY') {
1031 return map { $_ => $_ } @{$handles};
1033 elsif ($handle_type eq 'Regexp') {
1034 ($self->has_type_constraint)
1035 || $self->throw_error("Cannot delegate methods based on a Regexp without a type constraint (isa)", data => $handles);
1036 return map { ($_ => $_) }
1037 grep { /$handles/ } $self->_get_delegate_method_list;
1039 elsif ($handle_type eq 'CODE') {
1040 return $handles->($self, $self->_find_delegate_metaclass);
1042 elsif (blessed($handles) && $handles->isa('Moose::Meta::TypeConstraint::DuckType')) {
1043 return map { $_ => $_ } @{ $handles->methods };
1045 elsif (blessed($handles) && $handles->isa('Moose::Meta::TypeConstraint::Role')) {
1046 $handles = $handles->role;
1049 $self->throw_error("Unable to canonicalize the 'handles' option with $handles", data => $handles);
1053 Class::MOP::load_class($handles);
1054 my $role_meta = Class::MOP::class_of($handles);
1056 (blessed $role_meta && $role_meta->isa('Moose::Meta::Role'))
1057 || $self->throw_error("Unable to canonicalize the 'handles' option with $handles because its metaclass is not a Moose::Meta::Role", data => $handles);
1059 return map { $_ => $_ }
1061 grep { !$_->isa('Class::MOP::Method::Meta') } (
1062 $role_meta->_get_local_methods,
1063 $role_meta->get_required_method_list,
1067 sub _get_delegate_method_list {
1069 my $meta = $self->_find_delegate_metaclass;
1070 if ($meta->isa('Class::MOP::Class')) {
1071 return map { $_->name } # NOTE: !never! delegate &meta
1072 grep { $_->package_name ne 'Moose::Object' && !$_->isa('Class::MOP::Method::Meta') }
1073 $meta->get_all_methods;
1075 elsif ($meta->isa('Moose::Meta::Role')) {
1076 return $meta->get_method_list;
1079 $self->throw_error("Unable to recognize the delegate metaclass '$meta'", data => $meta);
1083 sub _find_delegate_metaclass {
1085 if (my $class = $self->_isa_metadata) {
1086 unless ( Class::MOP::is_class_loaded($class) ) {
1089 'The %s attribute is trying to delegate to a class which has not been loaded - %s',
1094 # we might be dealing with a non-Moose class,
1095 # and need to make our own metaclass. if there's
1096 # already a metaclass, it will be returned
1097 return Class::MOP::Class->initialize($class);
1099 elsif (my $role = $self->_does_metadata) {
1100 unless ( Class::MOP::is_class_loaded($class) ) {
1103 'The %s attribute is trying to delegate to a role which has not been loaded - %s',
1109 return Class::MOP::class_of($role);
1112 $self->throw_error("Cannot find delegate metaclass for attribute " . $self->name);
1116 sub delegation_metaclass { 'Moose::Meta::Method::Delegation' }
1118 sub _make_delegation_method {
1119 my ( $self, $handle_name, $method_to_call ) = @_;
1121 my @curried_arguments;
1123 ($method_to_call, @curried_arguments) = @$method_to_call
1124 if 'ARRAY' eq ref($method_to_call);
1126 return $self->delegation_metaclass->new(
1127 name => $handle_name,
1128 package_name => $self->associated_class->name,
1130 delegate_to_method => $method_to_call,
1131 curried_arguments => \@curried_arguments,
1135 sub _coerce_and_verify {
1138 my $instance = shift;
1140 return $val unless $self->has_type_constraint;
1142 $val = $self->type_constraint->coerce($val)
1143 if $self->should_coerce && $self->type_constraint->has_coercion;
1145 $self->verify_against_type_constraint($val, instance => $instance);
1150 sub verify_against_type_constraint {
1154 return 1 if !$self->has_type_constraint;
1156 my $type_constraint = $self->type_constraint;
1158 $type_constraint->check($val)
1159 || $self->throw_error("Attribute ("
1161 . ") does not pass the type constraint because: "
1162 . $type_constraint->get_message($val), data => $val, @_);
1165 package Moose::Meta::Attribute::Custom::Moose;
1166 sub register_implementation { 'Moose::Meta::Attribute' }
1170 # ABSTRACT: The Moose attribute metaclass
1178 This class is a subclass of L<Class::MOP::Attribute> that provides
1179 additional Moose-specific functionality.
1181 To really understand this class, you will need to start with the
1182 L<Class::MOP::Attribute> documentation. This class can be understood
1183 as a set of additional features on top of the basic feature provided
1184 by that parent class.
1188 C<Moose::Meta::Attribute> is a subclass of L<Class::MOP::Attribute>.
1192 Many of the documented below override methods in
1193 L<Class::MOP::Attribute> and add Moose specific features.
1199 =item B<< Moose::Meta::Attribute->new(%options) >>
1201 This method overrides the L<Class::MOP::Attribute> constructor.
1203 Many of the options below are described in more detail in the
1204 L<Moose::Manual::Attributes> document.
1206 It adds the following options to the constructor:
1210 =item * is => 'ro', 'rw', 'bare'
1212 This provides a shorthand for specifying the C<reader>, C<writer>, or
1213 C<accessor> names. If the attribute is read-only ('ro') then it will
1214 have a C<reader> method with the same attribute as the name.
1216 If it is read-write ('rw') then it will have an C<accessor> method
1217 with the same name. If you provide an explicit C<writer> for a
1218 read-write attribute, then you will have a C<reader> with the same
1219 name as the attribute, and a C<writer> with the name you provided.
1221 Use 'bare' when you are deliberately not installing any methods
1222 (accessor, reader, etc.) associated with this attribute; otherwise,
1223 Moose will issue a deprecation warning when this attribute is added to a
1226 =item * isa => $type
1228 This option accepts a type. The type can be a string, which should be
1229 a type name. If the type name is unknown, it is assumed to be a class
1232 This option can also accept a L<Moose::Meta::TypeConstraint> object.
1234 If you I<also> provide a C<does> option, then your C<isa> option must
1235 be a class name, and that class must do the role specified with
1238 =item * does => $role
1240 This is short-hand for saying that the attribute's type must be an
1241 object which does the named role.
1243 =item * coerce => $bool
1245 This option is only valid for objects with a type constraint
1246 (C<isa>) that defined a coercion. If this is true, then coercions will be applied whenever
1247 this attribute is set.
1249 You can make both this and the C<weak_ref> option true.
1251 =item * trigger => $sub
1253 This option accepts a subroutine reference, which will be called after
1254 the attribute is set.
1256 =item * required => $bool
1258 An attribute which is required must be provided to the constructor. An
1259 attribute which is required can also have a C<default> or C<builder>,
1260 which will satisfy its required-ness.
1262 A required attribute must have a C<default>, C<builder> or a
1263 non-C<undef> C<init_arg>
1265 =item * lazy => $bool
1267 A lazy attribute must have a C<default> or C<builder>. When an
1268 attribute is lazy, the default value will not be calculated until the
1271 =item * weak_ref => $bool
1273 If this is true, the attribute's value will be stored as a weak
1276 =item * auto_deref => $bool
1278 If this is true, then the reader will dereference the value when it is
1279 called. The attribute must have a type constraint which defines the
1280 attribute as an array or hash reference.
1282 =item * lazy_build => $bool
1284 Setting this to true makes the attribute lazy and provides a number of
1292 is equivalent to this:
1297 builder => '_build_size',
1298 clearer => 'clear_size',
1299 predicate => 'has_size',
1303 If your attribute name starts with an underscore (C<_>), then the clearer
1304 and predicate will as well:
1316 builder => '_build__size',
1317 clearer => '_clear_size',
1318 predicate => '_has_size',
1321 Note the doubled underscore in the builder name. Internally, Moose
1322 simply prepends the attribute name with "_build_" to come up with the
1325 =item * documentation
1327 An arbitrary string that can be retrieved later by calling C<<
1328 $attr->documentation >>.
1332 =item B<< $attr->clone(%options) >>
1334 This creates a new attribute based on attribute being cloned. You must
1335 supply a C<name> option to provide a new name for the attribute.
1337 The C<%options> can only specify options handled by
1338 L<Class::MOP::Attribute>.
1342 =head2 Value management
1346 =item B<< $attr->initialize_instance_slot($meta_instance, $instance, $params) >>
1348 This method is used internally to initialize the attribute's slot in
1349 the object C<$instance>.
1351 This overrides the L<Class::MOP::Attribute> method to handle lazy
1352 attributes, weak references, and type constraints.
1358 eval { $point->meta->get_attribute('x')->set_value($point, 'forty-two') };
1363 I<Attribute (x) does not pass the type constraint (Int) with 'forty-two'>
1365 Before setting the value, a check is made on the type constraint of
1366 the attribute, if it has one, to see if the value passes it. If the
1367 value fails to pass, the set operation dies with a L</throw_error>.
1369 Any coercion to convert values is done before checking the type constraint.
1371 To check a value against a type constraint before setting it, fetch the
1372 attribute instance using L<Class::MOP::Class/find_attribute_by_name>,
1373 fetch the type_constraint from the attribute using L<Moose::Meta::Attribute/type_constraint>
1374 and call L<Moose::Meta::TypeConstraint/check>. See L<Moose::Cookbook::Basics::Recipe4>
1379 =head2 Attribute Accessor generation
1383 =item B<< $attr->install_accessors >>
1385 This method overrides the parent to also install delegation methods.
1387 If, after installing all methods, the attribute object has no associated
1388 methods, it throws an error unless C<< is => 'bare' >> was passed to the
1389 attribute constructor. (Trying to add an attribute that has no associated
1390 methods is almost always an error.)
1392 =item B<< $attr->remove_accessors >>
1394 This method overrides the parent to also remove delegation methods.
1396 =item B<< $attr->inline_set($instance_var, $value_var) >>
1398 This method return a code snippet suitable for inlining the relevant
1399 operation. It expect strings containing variable names to be used in the
1400 inlining, like C<'$self'> or C<'$_[1]'>.
1402 =item B<< $attr->install_delegation >>
1404 This method adds its delegation methods to the attribute's associated
1405 class, if it has any to add.
1407 =item B<< $attr->remove_delegation >>
1409 This method remove its delegation methods from the attribute's
1412 =item B<< $attr->accessor_metaclass >>
1414 Returns the accessor metaclass name, which defaults to
1415 L<Moose::Meta::Method::Accessor>.
1417 =item B<< $attr->delegation_metaclass >>
1419 Returns the delegation metaclass name, which defaults to
1420 L<Moose::Meta::Method::Delegation>.
1424 =head2 Additional Moose features
1426 These methods are not found in the superclass. They support features
1431 =item B<< $attr->does($role) >>
1433 This indicates whether the I<attribute itself> does the given
1434 role. The role can be given as a full class name, or as a resolvable
1437 Note that this checks the attribute itself, not its type constraint,
1438 so it is checking the attribute's metaclass and any traits applied to
1441 =item B<< Moose::Meta::Class->interpolate_class_and_new($name, %options) >>
1443 This is an alternate constructor that handles the C<metaclass> and
1446 Effectively, this method is a factory that finds or creates the
1447 appropriate class for the given C<metaclass> and/or C<traits>.
1449 Once it has the appropriate class, it will call C<< $class->new($name,
1450 %options) >> on that class.
1452 =item B<< $attr->clone_and_inherit_options(%options) >>
1454 This method supports the C<has '+foo'> feature. It does various bits
1455 of processing on the supplied C<%options> before ultimately calling
1456 the C<clone> method.
1458 One of its main tasks is to make sure that the C<%options> provided
1459 does not include the options returned by the
1460 C<illegal_options_for_inheritance> method.
1462 =item B<< $attr->illegal_options_for_inheritance >>
1464 This returns a blacklist of options that can not be overridden in a
1465 subclass's attribute definition.
1467 This exists to allow a custom metaclass to change or add to the list
1468 of options which can not be changed.
1470 =item B<< $attr->type_constraint >>
1472 Returns the L<Moose::Meta::TypeConstraint> object for this attribute,
1475 =item B<< $attr->has_type_constraint >>
1477 Returns true if this attribute has a type constraint.
1479 =item B<< $attr->verify_against_type_constraint($value) >>
1481 Given a value, this method returns true if the value is valid for the
1482 attribute's type constraint. If the value is not valid, it throws an
1485 =item B<< $attr->handles >>
1487 This returns the value of the C<handles> option passed to the
1490 =item B<< $attr->has_handles >>
1492 Returns true if this attribute performs delegation.
1494 =item B<< $attr->is_weak_ref >>
1496 Returns true if this attribute stores its value as a weak reference.
1498 =item B<< $attr->is_required >>
1500 Returns true if this attribute is required to have a value.
1502 =item B<< $attr->is_lazy >>
1504 Returns true if this attribute is lazy.
1506 =item B<< $attr->is_lazy_build >>
1508 Returns true if the C<lazy_build> option was true when passed to the
1511 =item B<< $attr->should_coerce >>
1513 Returns true if the C<coerce> option passed to the constructor was
1516 =item B<< $attr->should_auto_deref >>
1518 Returns true if the C<auto_deref> option passed to the constructor was
1521 =item B<< $attr->trigger >>
1523 This is the subroutine reference that was in the C<trigger> option
1524 passed to the constructor, if any.
1526 =item B<< $attr->has_trigger >>
1528 Returns true if this attribute has a trigger set.
1530 =item B<< $attr->documentation >>
1532 Returns the value that was in the C<documentation> option passed to
1533 the constructor, if any.
1535 =item B<< $attr->has_documentation >>
1537 Returns true if this attribute has any documentation.
1539 =item B<< $attr->applied_traits >>
1541 This returns an array reference of all the traits which were applied
1542 to this attribute. If none were applied, this returns C<undef>.
1544 =item B<< $attr->has_applied_traits >>
1546 Returns true if this attribute has any traits applied.
1552 See L<Moose/BUGS> for details on reporting bugs.