1 package Mouse::Meta::Attribute;
7 use Mouse::Util qw(:meta);
9 use Mouse::Meta::TypeConstraint;
10 use Mouse::Meta::Method::Accessor;
13 my($class, $name, $args) = @_;
16 # XXX: for backward compatibility (with method modifiers)
17 if($class->can('canonicalize_args') != \&canonicalize_args){
18 %{$args} = $class->canonicalize_args($name, %{$args});
21 # taken from Class::MOP::Attribute::new
24 or $class->throw_error('You must provide a name for the attribute');
26 if(!exists $args->{init_arg}){
27 $args->{init_arg} = $name;
30 # 'required' requires eigher 'init_arg', 'builder', or 'default'
31 my $can_be_required = defined( $args->{init_arg} );
33 if(exists $args->{builder}){
35 # Moose refuses a CODE ref builder, but Mouse doesn't for backward compatibility
36 # This feature will be changed in a future. (gfx)
37 $class->throw_error('builder must be a defined scalar value which is a method name')
38 #if ref $args->{builder} || !defined $args->{builder};
39 if !defined $args->{builder};
43 elsif(exists $args->{default}){
44 if(ref $args->{default} && ref($args->{default}) ne 'CODE'){
45 $class->throw_error("References are not allowed as default values, you must "
46 . "wrap the default of '$name' in a CODE reference (ex: sub { [] } and not [])");
51 if( $args->{required} && !$can_be_required ) {
52 $class->throw_error("You cannot have a required attribute ($name) without a default, builder, or an init_arg");
55 # taken from Mouse::Meta::Attribute->new and _process_args->
57 if(exists $args->{is}){
61 $args->{reader} ||= $name;
64 if(exists $args->{writer}){
65 $args->{reader} ||= $name;
68 $args->{accessor} ||= $name;
72 # do nothing, but don't complain (later) about missing methods
75 $is = 'undef' if !defined $is;
76 $class->throw_error("I do not understand this option (is => $is) on attribute ($name)");
81 if(exists $args->{isa}){
82 $args->{type_constraint} = Mouse::Util::TypeConstraints::find_or_create_isa_type_constraint($args->{isa});
84 elsif(exists $args->{does}){
86 # $args->{type_constraint} = Mouse::Util::TypeConstraints::find_or_create_does_type_constraint($args->{does});
88 $tc = $args->{type_constraint};
92 || $class->throw_error("You cannot have coercion without specifying a type constraint on attribute ($name)");
95 && $class->throw_error("You cannot have a weak reference to a coerced value on attribute ($name)");
98 if ($args->{lazy_build}) {
99 exists($args->{default})
100 && $class->throw_error("You can not use lazy_build and default for the same attribute ($name)");
103 $args->{builder} ||= "_build_${name}";
105 $args->{clearer} ||= "_clear${name}";
106 $args->{predicate} ||= "_has${name}";
109 $args->{clearer} ||= "clear_${name}";
110 $args->{predicate} ||= "has_${name}";
114 if ($args->{auto_deref}) {
116 || $class->throw_error("You cannot auto-dereference without specifying a type constraint on attribute ($name)");
118 ( $tc->is_a_type_of('ArrayRef') || $tc->is_a_type_of('HashRef') )
119 || $class->throw_error("You cannot auto-dereference anything other than a ArrayRef or HashRef on attribute ($name)");
122 if (exists $args->{trigger}) {
123 ('CODE' eq ref $args->{trigger})
124 || $class->throw_error("Trigger must be a CODE ref on attribute ($name)");
128 (exists $args->{default} || defined $args->{builder})
129 || $class->throw_error("You cannot have lazy attribute ($name) without specifying a default value for it");
139 my %args = (@_ == 1) ? %{ $_[0] } : @_;
141 $class->_process_options($name, \%args);
145 my $self = bless \%args, $class;
148 if($class ne __PACKAGE__){
149 $class->meta->_initialize_object($self, \%args);
152 # XXX: there is no fast way to check attribute validity
156 # Carp::cluck("Found unknown argument(s) passed to '$name' attribute constructor in '$class': @bad");
164 sub name { $_[0]->{name} }
165 sub associated_class { $_[0]->{associated_class} }
167 sub accessor { $_[0]->{accessor} }
168 sub reader { $_[0]->{reader} }
169 sub writer { $_[0]->{writer} }
170 sub predicate { $_[0]->{predicate} }
171 sub clearer { $_[0]->{clearer} }
172 sub handles { $_[0]->{handles} }
174 sub _is_metadata { $_[0]->{is} }
175 sub is_required { $_[0]->{required} }
176 sub default { $_[0]->{default} }
177 sub is_lazy { $_[0]->{lazy} }
178 sub is_lazy_build { $_[0]->{lazy_build} }
179 sub is_weak_ref { $_[0]->{weak_ref} }
180 sub init_arg { $_[0]->{init_arg} }
181 sub type_constraint { $_[0]->{type_constraint} }
183 sub trigger { $_[0]->{trigger} }
184 sub builder { $_[0]->{builder} }
185 sub should_auto_deref { $_[0]->{auto_deref} }
186 sub should_coerce { $_[0]->{coerce} }
188 sub get_read_method { $_[0]->{reader} || $_[0]->{accessor} }
189 sub get_write_method { $_[0]->{writer} || $_[0]->{accessor} }
193 sub has_accessor { exists $_[0]->{accessor} }
194 sub has_reader { exists $_[0]->{reader} }
195 sub has_writer { exists $_[0]->{writer} }
196 sub has_predicate { exists $_[0]->{predicate} }
197 sub has_clearer { exists $_[0]->{clearer} }
198 sub has_handles { exists $_[0]->{handles} }
200 sub has_default { exists $_[0]->{default} }
201 sub has_type_constraint { exists $_[0]->{type_constraint} }
202 sub has_trigger { exists $_[0]->{trigger} }
203 sub has_builder { exists $_[0]->{builder} }
205 sub has_read_method { exists $_[0]->{reader} || exists $_[0]->{accessor} }
206 sub has_write_method { exists $_[0]->{writer} || exists $_[0]->{accessor} }
209 $_[0]->{_create_args} = $_[1] if @_ > 1;
210 $_[0]->{_create_args}
213 sub interpolate_class{
214 my($class, $name, $args) = @_;
216 if(my $metaclass = delete $args->{metaclass}){
217 $class = Mouse::Util::resolve_metaclass_alias( Attribute => $metaclass );
221 if(my $traits_ref = delete $args->{traits}){
223 for (my $i = 0; $i < @{$traits_ref}; $i++) {
224 my $trait = Mouse::Util::resolve_metaclass_alias(Attribute => $traits_ref->[$i], trait => 1);
226 next if $class->does($trait);
228 push @traits, $trait;
231 push @traits, $traits_ref->[++$i]
232 if ref($traits_ref->[$i+1]);
236 $class = Mouse::Meta::Class->create_anon_class(
237 superclasses => [ $class ],
244 return( $class, @traits );
247 sub canonicalize_args{
248 my ($self, $name, %args) = @_;
250 Carp::cluck("$self->canonicalize_args has been deprecated."
251 . "Use \$self->_process_options instead.")
258 my ($self, $class, $name, %args) = @_;
260 Carp::cluck("$self->create has been deprecated."
261 . "Use \$meta->add_attribute and \$attr->install_accessors instead.")
268 sub _coerce_and_verify {
269 my($self, $value, $instance) = @_;
271 my $type_constraint = $self->{type_constraint};
273 return $value if !$type_constraint;
275 if ($self->should_coerce && $type_constraint->has_coercion) {
276 $value = $type_constraint->coerce($value);
279 return $value if $type_constraint->check($value);
281 $self->verify_against_type_constraint($value);
286 sub verify_against_type_constraint {
287 my ($self, $value) = @_;
289 my $type_constraint = $self->{type_constraint};
290 return 1 if !$type_constraint;;
291 return 1 if $type_constraint->check($value);
293 $self->verify_type_constraint_error($self->name, $value, $type_constraint);
296 sub verify_type_constraint_error {
297 my($self, $name, $value, $type) = @_;
298 $self->throw_error("Attribute ($name) does not pass the type constraint because: " . $type->get_message($value));
301 sub coerce_constraint { ## my($self, $value) = @_;
302 my $type = $_[0]->{type_constraint}
305 Carp::cluck("coerce_constraint() has been deprecated, which was an internal utility anyway");
307 return Mouse::Util::TypeConstraints->typecast_constraints($_[0]->associated_class->name, $type, $_[1]);
310 sub _canonicalize_handles {
314 if (ref($handles) eq 'HASH') {
317 elsif (ref($handles) eq 'ARRAY') {
318 return map { $_ => $_ } @$handles;
321 $self->throw_error("Unable to canonicalize the 'handles' option with $handles");
325 sub clone_and_inherit_options{
329 return ref($self)->new($name, %{$self}, (@_ == 1) ? %{$_[0]} : @_);
336 my %args = ($self->get_parent_args($class, $name), @_);
338 Carp::cluck("$self->clone_parent has been deprecated."
339 . "Use \$meta->add_attribute and \$attr->install_accessors instead.")
342 $self->clone_and_inherited_args($class, $name, %args);
345 sub get_parent_args {
350 for my $super ($class->linearized_isa) {
351 my $super_attr = $super->can("meta") && $super->meta->get_attribute($name)
353 return %{ $super_attr->_create_args };
356 $self->throw_error("Could not find an attribute by the name of '$name' to inherit from");
359 sub associate_method{
360 my ($attribute, $method) = @_;
361 $attribute->{associated_methods}++;
365 sub install_accessors{
368 my $metaclass = $attribute->{associated_class};
370 foreach my $type(qw(accessor reader writer predicate clearer handles)){
371 if(exists $attribute->{$type}){
372 my $installer = '_install_' . $type;
374 Mouse::Meta::Method::Accessor->$installer($attribute, $attribute->{$type}, $metaclass);
376 $attribute->{associated_methods}++;
380 if($attribute->can('create') != \&create){
381 # backword compatibility
382 $attribute->create($metaclass, $attribute->name, %{$attribute});
391 my $metaclass = (ref $self && $self->associated_class) || 'Mouse::Meta::Class';
392 $metaclass->throw_error(@_, depth => 1);
401 Mouse::Meta::Attribute - The Mouse attribute metaclass
405 =head2 C<< new(%options) -> Mouse::Meta::Attribute >>
407 Instantiates a new Mouse::Meta::Attribute. Does nothing else.
409 It adds the following options to the constructor:
413 =item C<< is => 'ro', 'rw', 'bare' >>
415 This provides a shorthand for specifying the C<reader>, C<writer>, or
416 C<accessor> names. If the attribute is read-only ('ro') then it will
417 have a C<reader> method with the same attribute as the name.
419 If it is read-write ('rw') then it will have an C<accessor> method
420 with the same name. If you provide an explicit C<writer> for a
421 read-write attribute, then you will have a C<reader> with the same
422 name as the attribute, and a C<writer> with the name you provided.
424 Use 'bare' when you are deliberately not installing any methods
425 (accessor, reader, etc.) associated with this attribute; otherwise,
426 Moose will issue a deprecation warning when this attribute is added to a
429 =item C<< isa => Type >>
431 This option accepts a type. The type can be a string, which should be
432 a type name. If the type name is unknown, it is assumed to be a class
435 This option can also accept a L<Moose::Meta::TypeConstraint> object.
437 If you I<also> provide a C<does> option, then your C<isa> option must
438 be a class name, and that class must do the role specified with
441 =item C<< does => Role >>
443 This is short-hand for saying that the attribute's type must be an
444 object which does the named role.
446 B<This option is not yet supported.>
448 =item C<< coerce => Bool >>
450 This option is only valid for objects with a type constraint
451 (C<isa>). If this is true, then coercions will be applied whenever
452 this attribute is set.
454 You can make both this and the C<weak_ref> option true.
456 =item C<< trigger => CodeRef >>
458 This option accepts a subroutine reference, which will be called after
459 the attribute is set.
461 =item C<< required => Bool >>
463 An attribute which is required must be provided to the constructor. An
464 attribute which is required can also have a C<default> or C<builder>,
465 which will satisfy its required-ness.
467 A required attribute must have a C<default>, C<builder> or a
468 non-C<undef> C<init_arg>
470 =item C<< lazy => Bool >>
472 A lazy attribute must have a C<default> or C<builder>. When an
473 attribute is lazy, the default value will not be calculated until the
476 =item C<< weak_ref => Bool >>
478 If this is true, the attribute's value will be stored as a weak
481 =item C<< auto_deref => Bool >>
483 If this is true, then the reader will dereference the value when it is
484 called. The attribute must have a type constraint which defines the
485 attribute as an array or hash reference.
487 =item C<< lazy_build => Bool >>
489 Setting this to true makes the attribute lazy and provides a number of
497 is equivalent to this:
502 builder => '_build_size',
503 clearer => 'clear_size',
504 predicate => 'has_size',
509 =head2 C<< associate_method(Method) >>
511 Associates a method with the attribute. Typically, this is called internally
512 when an attribute generates its accessors.
514 Currently the argument I<Method> is ignored in Mouse.
516 =head2 C<< verify_against_type_constraint(Item) -> TRUE | ERROR >>
518 Checks that the given value passes this attribute's type constraint. Returns C<true>
519 on success, otherwise C<confess>es.
521 =head2 C<< clone_and_inherit_options(options) -> Mouse::Meta::Attribute >>
523 Creates a new attribute in the owner class, inheriting options from parent classes.
524 Accessors and helper methods are installed. Some error checking is done.
528 L<Moose::Meta::Attribute>
530 L<Class::MOP::Attribute>