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} }
190 sub has_accessor { exists $_[0]->{accessor} }
191 sub has_reader { exists $_[0]->{reader} }
192 sub has_writer { exists $_[0]->{writer} }
193 sub has_predicate { exists $_[0]->{predicate} }
194 sub has_clearer { exists $_[0]->{clearer} }
195 sub has_handles { exists $_[0]->{handles} }
197 sub has_default { exists $_[0]->{default} }
198 sub has_type_constraint { exists $_[0]->{type_constraint} }
199 sub has_trigger { exists $_[0]->{trigger} }
200 sub has_builder { exists $_[0]->{builder} }
202 sub has_read_method { exists $_[0]->{reader} || exists $_[0]->{accessor} }
203 sub has_write_method { exists $_[0]->{writer} || exists $_[0]->{accessor} }
206 $_[0]->{_create_args} = $_[1] if @_ > 1;
207 $_[0]->{_create_args}
210 sub interpolate_class{
211 my($class, $name, $args) = @_;
213 if(my $metaclass = delete $args->{metaclass}){
214 $class = Mouse::Util::resolve_metaclass_alias( Attribute => $metaclass );
218 if(my $traits_ref = delete $args->{traits}){
220 for (my $i = 0; $i < @{$traits_ref}; $i++) {
221 my $trait = Mouse::Util::resolve_metaclass_alias(Attribute => $traits_ref->[$i], trait => 1);
223 next if $class->does($trait);
225 push @traits, $trait;
228 push @traits, $traits_ref->[++$i]
229 if ref($traits_ref->[$i+1]);
233 $class = Mouse::Meta::Class->create_anon_class(
234 superclasses => [ $class ],
241 return( $class, @traits );
244 sub canonicalize_args{
245 my ($self, $name, %args) = @_;
247 Carp::cluck("$self->canonicalize_args has been deprecated."
248 . "Use \$self->_process_options instead.")
255 my ($self, $class, $name, %args) = @_;
257 Carp::cluck("$self->create has been deprecated."
258 . "Use \$meta->add_attribute and \$attr->install_accessors instead.")
265 sub _coerce_and_verify {
266 my($self, $value, $instance) = @_;
268 my $type_constraint = $self->{type_constraint};
270 return $value if !$type_constraint;
272 if ($self->should_coerce && $type_constraint->has_coercion) {
273 $value = $type_constraint->coerce($value);
276 return $value if $type_constraint->check($value);
278 $self->verify_against_type_constraint($value);
283 sub verify_against_type_constraint {
284 my ($self, $value) = @_;
286 my $type_constraint = $self->{type_constraint};
287 return 1 if !$type_constraint;;
288 return 1 if $type_constraint->check($value);
290 $self->verify_type_constraint_error($self->name, $value, $type_constraint);
293 sub verify_type_constraint_error {
294 my($self, $name, $value, $type) = @_;
295 $self->throw_error("Attribute ($name) does not pass the type constraint because: " . $type->get_message($value));
298 sub coerce_constraint { ## my($self, $value) = @_;
299 my $type = $_[0]->{type_constraint}
302 Carp::cluck("coerce_constraint() has been deprecated, which was an internal utility anyway");
304 return Mouse::Util::TypeConstraints->typecast_constraints($_[0]->associated_class->name, $type, $_[1]);
307 sub _canonicalize_handles {
311 if (ref($handles) eq 'HASH') {
314 elsif (ref($handles) eq 'ARRAY') {
315 return map { $_ => $_ } @$handles;
318 $self->throw_error("Unable to canonicalize the 'handles' option with $handles");
322 sub clone_and_inherit_options{
326 return ref($self)->new($name, %{$self}, (@_ == 1) ? %{$_[0]} : @_);
333 my %args = ($self->get_parent_args($class, $name), @_);
335 Carp::cluck("$self->clone_parent has been deprecated."
336 . "Use \$meta->add_attribute and \$attr->install_accessors instead.")
339 $self->clone_and_inherited_args($class, $name, %args);
342 sub get_parent_args {
347 for my $super ($class->linearized_isa) {
348 my $super_attr = $super->can("meta") && $super->meta->get_attribute($name)
350 return %{ $super_attr->_create_args };
353 $self->throw_error("Could not find an attribute by the name of '$name' to inherit from");
357 #sub get_read_method { $_[0]->{reader} || $_[0]->{accessor} }
358 #sub get_write_method { $_[0]->{writer} || $_[0]->{accessor} }
360 sub get_read_method_ref{
363 $self->{_read_method_ref} ||= do{
364 my $metaclass = $self->associated_class
365 or $self->throw_error('No asocciated class for ' . $self->name);
367 my $reader = $self->{reader} || $self->{accessor};
369 $metaclass->name->can($reader);
372 Mouse::Meta::Method::Accessor->_generate_reader($self, undef, $metaclass);
377 sub get_write_method_ref{
380 $self->{_write_method_ref} ||= do{
381 my $metaclass = $self->associated_class
382 or $self->throw_error('No asocciated class for ' . $self->name);
384 my $reader = $self->{writer} || $self->{accessor};
386 $metaclass->name->can($reader);
389 Mouse::Meta::Method::Accessor->_generate_writer($self, undef, $metaclass);
394 sub associate_method{
395 my ($attribute, $method) = @_;
396 $attribute->{associated_methods}++;
400 sub install_accessors{
403 my $metaclass = $attribute->{associated_class};
405 foreach my $type(qw(accessor reader writer predicate clearer handles)){
406 if(exists $attribute->{$type}){
407 my $installer = '_generate_' . $type;
409 Mouse::Meta::Method::Accessor->$installer($attribute, $attribute->{$type}, $metaclass);
411 $attribute->{associated_methods}++;
415 if($attribute->can('create') != \&create){
416 # backword compatibility
417 $attribute->create($metaclass, $attribute->name, %{$attribute});
426 my $metaclass = (ref $self && $self->associated_class) || 'Mouse::Meta::Class';
427 $metaclass->throw_error(@_, depth => 1);
436 Mouse::Meta::Attribute - The Mouse attribute metaclass
440 =head2 C<< new(%options) -> Mouse::Meta::Attribute >>
442 Instantiates a new Mouse::Meta::Attribute. Does nothing else.
444 It adds the following options to the constructor:
448 =item C<< is => 'ro', 'rw', 'bare' >>
450 This provides a shorthand for specifying the C<reader>, C<writer>, or
451 C<accessor> names. If the attribute is read-only ('ro') then it will
452 have a C<reader> method with the same attribute as the name.
454 If it is read-write ('rw') then it will have an C<accessor> method
455 with the same name. If you provide an explicit C<writer> for a
456 read-write attribute, then you will have a C<reader> with the same
457 name as the attribute, and a C<writer> with the name you provided.
459 Use 'bare' when you are deliberately not installing any methods
460 (accessor, reader, etc.) associated with this attribute; otherwise,
461 Moose will issue a deprecation warning when this attribute is added to a
464 =item C<< isa => Type >>
466 This option accepts a type. The type can be a string, which should be
467 a type name. If the type name is unknown, it is assumed to be a class
470 This option can also accept a L<Moose::Meta::TypeConstraint> object.
472 If you I<also> provide a C<does> option, then your C<isa> option must
473 be a class name, and that class must do the role specified with
476 =item C<< does => Role >>
478 This is short-hand for saying that the attribute's type must be an
479 object which does the named role.
481 B<This option is not yet supported.>
483 =item C<< coerce => Bool >>
485 This option is only valid for objects with a type constraint
486 (C<isa>). If this is true, then coercions will be applied whenever
487 this attribute is set.
489 You can make both this and the C<weak_ref> option true.
491 =item C<< trigger => CodeRef >>
493 This option accepts a subroutine reference, which will be called after
494 the attribute is set.
496 =item C<< required => Bool >>
498 An attribute which is required must be provided to the constructor. An
499 attribute which is required can also have a C<default> or C<builder>,
500 which will satisfy its required-ness.
502 A required attribute must have a C<default>, C<builder> or a
503 non-C<undef> C<init_arg>
505 =item C<< lazy => Bool >>
507 A lazy attribute must have a C<default> or C<builder>. When an
508 attribute is lazy, the default value will not be calculated until the
511 =item C<< weak_ref => Bool >>
513 If this is true, the attribute's value will be stored as a weak
516 =item C<< auto_deref => Bool >>
518 If this is true, then the reader will dereference the value when it is
519 called. The attribute must have a type constraint which defines the
520 attribute as an array or hash reference.
522 =item C<< lazy_build => Bool >>
524 Setting this to true makes the attribute lazy and provides a number of
532 is equivalent to this:
537 builder => '_build_size',
538 clearer => 'clear_size',
539 predicate => 'has_size',
544 =head2 C<< associate_method(Method) >>
546 Associates a method with the attribute. Typically, this is called internally
547 when an attribute generates its accessors.
549 Currently the argument I<Method> is ignored in Mouse.
551 =head2 C<< verify_against_type_constraint(Item) -> TRUE | ERROR >>
553 Checks that the given value passes this attribute's type constraint. Returns C<true>
554 on success, otherwise C<confess>es.
556 =head2 C<< clone_and_inherit_options(options) -> Mouse::Meta::Attribute >>
558 Creates a new attribute in the owner class, inheriting options from parent classes.
559 Accessors and helper methods are installed. Some error checking is done.
563 L<Moose::Meta::Attribute>
565 L<Class::MOP::Attribute>