1 package Mouse::Meta::Attribute;
2 use Mouse::Util qw(:meta); # enables strict and warnings
6 use Mouse::Meta::TypeConstraint;
7 use Mouse::Meta::Method::Accessor;
11 my($class, $name, $args) = @_;
14 # XXX: for backward compatibility (with method modifiers)
15 if($class->can('canonicalize_args') != \&canonicalize_args){
16 %{$args} = $class->canonicalize_args($name, %{$args});
19 # taken from Class::MOP::Attribute::new
22 or $class->throw_error('You must provide a name for the attribute');
24 if(!exists $args->{init_arg}){
25 $args->{init_arg} = $name;
28 # 'required' requires eigher 'init_arg', 'builder', or 'default'
29 my $can_be_required = defined( $args->{init_arg} );
31 if(exists $args->{builder}){
33 # Moose refuses a CODE ref builder, but Mouse doesn't for backward compatibility
34 # This feature will be changed in a future. (gfx)
35 $class->throw_error('builder must be a defined scalar value which is a method name')
36 #if ref $args->{builder} || !defined $args->{builder};
37 if !defined $args->{builder};
41 elsif(exists $args->{default}){
42 if(ref $args->{default} && ref($args->{default}) ne 'CODE'){
43 $class->throw_error("References are not allowed as default values, you must "
44 . "wrap the default of '$name' in a CODE reference (ex: sub { [] } and not [])");
49 if( $args->{required} && !$can_be_required ) {
50 $class->throw_error("You cannot have a required attribute ($name) without a default, builder, or an init_arg");
53 # taken from Mouse::Meta::Attribute->new and _process_args->
55 if(exists $args->{is}){
59 $args->{reader} ||= $name;
62 if(exists $args->{writer}){
63 $args->{reader} ||= $name;
66 $args->{accessor} ||= $name;
70 # do nothing, but don't complain (later) about missing methods
73 $is = 'undef' if !defined $is;
74 $class->throw_error("I do not understand this option (is => $is) on attribute ($name)");
79 if(exists $args->{isa}){
80 $args->{type_constraint} = Mouse::Util::TypeConstraints::find_or_create_isa_type_constraint($args->{isa});
82 elsif(exists $args->{does}){
83 $args->{type_constraint} = Mouse::Util::TypeConstraints::find_or_create_does_type_constraint($args->{does});
85 $tc = $args->{type_constraint};
89 || $class->throw_error("You cannot have coercion without specifying a type constraint on attribute ($name)");
92 && $class->throw_error("You cannot have a weak reference to a coerced value on attribute ($name)");
95 if ($args->{lazy_build}) {
96 exists($args->{default})
97 && $class->throw_error("You can not use lazy_build and default for the same attribute ($name)");
100 $args->{builder} ||= "_build_${name}";
102 $args->{clearer} ||= "_clear${name}";
103 $args->{predicate} ||= "_has${name}";
106 $args->{clearer} ||= "clear_${name}";
107 $args->{predicate} ||= "has_${name}";
111 if ($args->{auto_deref}) {
113 || $class->throw_error("You cannot auto-dereference without specifying a type constraint on attribute ($name)");
115 ( $tc->is_a_type_of('ArrayRef') || $tc->is_a_type_of('HashRef') )
116 || $class->throw_error("You cannot auto-dereference anything other than a ArrayRef or HashRef on attribute ($name)");
119 if (exists $args->{trigger}) {
120 ('CODE' eq ref $args->{trigger})
121 || $class->throw_error("Trigger must be a CODE ref on attribute ($name)");
125 (exists $args->{default} || defined $args->{builder})
126 || $class->throw_error("You cannot have lazy attribute ($name) without specifying a default value for it");
136 my %args = (@_ == 1) ? %{ $_[0] } : @_;
138 $class->_process_options($name, \%args);
142 my $self = bless \%args, $class;
145 if($class ne __PACKAGE__){
146 $class->meta->_initialize_object($self, \%args);
149 # XXX: there is no fast way to check attribute validity
153 # Carp::cluck("Found unknown argument(s) passed to '$name' attribute constructor in '$class': @bad");
161 sub name { $_[0]->{name} }
162 sub associated_class { $_[0]->{associated_class} }
164 sub accessor { $_[0]->{accessor} }
165 sub reader { $_[0]->{reader} }
166 sub writer { $_[0]->{writer} }
167 sub predicate { $_[0]->{predicate} }
168 sub clearer { $_[0]->{clearer} }
169 sub handles { $_[0]->{handles} }
171 sub _is_metadata { $_[0]->{is} }
172 sub is_required { $_[0]->{required} }
173 sub default { $_[0]->{default} }
174 sub is_lazy { $_[0]->{lazy} }
175 sub is_lazy_build { $_[0]->{lazy_build} }
176 sub is_weak_ref { $_[0]->{weak_ref} }
177 sub init_arg { $_[0]->{init_arg} }
178 sub type_constraint { $_[0]->{type_constraint} }
180 sub trigger { $_[0]->{trigger} }
181 sub builder { $_[0]->{builder} }
182 sub should_auto_deref { $_[0]->{auto_deref} }
183 sub should_coerce { $_[0]->{coerce} }
187 sub has_accessor { exists $_[0]->{accessor} }
188 sub has_reader { exists $_[0]->{reader} }
189 sub has_writer { exists $_[0]->{writer} }
190 sub has_predicate { exists $_[0]->{predicate} }
191 sub has_clearer { exists $_[0]->{clearer} }
192 sub has_handles { exists $_[0]->{handles} }
194 sub has_default { exists $_[0]->{default} }
195 sub has_type_constraint { exists $_[0]->{type_constraint} }
196 sub has_trigger { exists $_[0]->{trigger} }
197 sub has_builder { exists $_[0]->{builder} }
199 sub has_read_method { exists $_[0]->{reader} || exists $_[0]->{accessor} }
200 sub has_write_method { exists $_[0]->{writer} || exists $_[0]->{accessor} }
202 sub _create_args { # DEPRECATED
203 $_[0]->{_create_args} = $_[1] if @_ > 1;
204 $_[0]->{_create_args}
207 sub interpolate_class{
208 my($class, $args) = @_;
210 if(my $metaclass = delete $args->{metaclass}){
211 $class = Mouse::Util::resolve_metaclass_alias( Attribute => $metaclass );
215 if(my $traits_ref = delete $args->{traits}){
219 for (my $i = 0; $i < @{$traits_ref}; $i++) {
220 my $trait = Mouse::Util::resolve_metaclass_alias(Attribute => $traits_ref->[$i], trait => 1);
222 next if $class->does($trait);
224 push @traits, $trait;
227 push @traits, $traits_ref->[++$i]
228 if ref($traits_ref->[$i+1]);
231 warn "Fatal error in traits: $@" if _MOUSE_VERBOSE;
234 $class = Mouse::Meta::Class->create_anon_class(
235 superclasses => [ $class ],
242 return( $class, @traits );
245 sub canonicalize_args{ # DEPRECATED
246 my ($self, $name, %args) = @_;
248 Carp::cluck("$self->canonicalize_args has been deprecated."
249 . "Use \$self->_process_options instead.")
255 sub create { # DEPRECATED
256 my ($self, $class, $name, %args) = @_;
258 Carp::cluck("$self->create has been deprecated."
259 . "Use \$meta->add_attribute and \$attr->install_accessors instead.")
266 sub _coerce_and_verify {
267 my($self, $value, $instance) = @_;
269 my $type_constraint = $self->{type_constraint};
270 return $value if !defined $type_constraint;
272 if ($self->should_coerce && $type_constraint->has_coercion) {
273 $value = $type_constraint->coerce($value);
276 $self->verify_against_type_constraint($value);
281 sub verify_against_type_constraint {
282 my ($self, $value) = @_;
284 my $type_constraint = $self->{type_constraint};
285 return 1 if !$type_constraint;
286 return 1 if $type_constraint->check($value);
288 $self->verify_type_constraint_error($self->name, $value, $type_constraint);
291 sub verify_type_constraint_error {
292 my($self, $name, $value, $type) = @_;
293 $self->throw_error("Attribute ($name) does not pass the type constraint because: "
294 . $type->get_message($value));
297 sub coerce_constraint { # DEPRECATED
298 my $type = $_[0]->{type_constraint}
301 Carp::cluck("coerce_constraint() has been deprecated, which was an internal utility anyway");
303 return Mouse::Util::TypeConstraints->typecast_constraints($_[0]->associated_class->name, $type, $_[1]);
306 sub clone_and_inherit_options{
307 my($self, %args) = @_;
309 my($attribute_class, @traits) = ref($self)->interpolate_class(\%args);
311 $args{traits} = \@traits if @traits;
312 return $attribute_class->new($self->name, %{$self}, %args);
315 sub clone_parent { # DEPRECATED
319 my %args = ($self->get_parent_args($class, $name), @_);
321 Carp::cluck("$self->clone_parent has been deprecated."
322 . "Use \$meta->add_attribute and \$attr->install_accessors instead.")
325 $self->clone_and_inherited_args($class, $name, %args);
328 sub get_parent_args { # DEPRECATED
333 for my $super ($class->linearized_isa) {
334 my $super_attr = $super->can("meta") && $super->meta->get_attribute($name)
336 return %{ $super_attr->_create_args };
339 $self->throw_error("Could not find an attribute by the name of '$name' to inherit from");
343 sub get_read_method {
344 $_[0]->{reader} || $_[0]->{accessor}
346 sub get_write_method {
347 $_[0]->{writer} || $_[0]->{accessor}
350 sub get_read_method_ref{
353 $self->{_read_method_ref} ||= do{
354 my $metaclass = $self->associated_class
355 or $self->throw_error('No asocciated class for ' . $self->name);
357 my $reader = $self->{reader} || $self->{accessor};
359 $metaclass->name->can($reader);
362 $self->accessor_metaclass->_generate_reader($self, $metaclass);
367 sub get_write_method_ref{
370 $self->{_write_method_ref} ||= do{
371 my $metaclass = $self->associated_class
372 or $self->throw_error('No asocciated class for ' . $self->name);
374 my $reader = $self->{writer} || $self->{accessor};
376 $metaclass->name->can($reader);
379 $self->accessor_metaclass->_generate_writer($self, $metaclass);
384 sub _canonicalize_handles {
385 my($self, $handles) = @_;
387 if (ref($handles) eq 'HASH') {
390 elsif (ref($handles) eq 'ARRAY') {
391 return map { $_ => $_ } @$handles;
393 elsif (ref($handles) eq 'Regexp') {
394 my $class_or_role = ($self->{isa} || $self->{does})
395 || $self->throw_error("Cannot delegate methods based on a Regexp without a type constraint (isa)");
397 my $meta = Mouse::Meta::Class->initialize("$class_or_role"); # "" for stringify
398 return map { $_ => $_ }
399 grep { $_ ne 'meta' && !Mouse::Object->can($_) && $_ =~ $handles }
400 $meta->isa('Mouse::Meta::Class') ? $meta->get_all_method_names : $meta->get_method_list;
403 $self->throw_error("Unable to canonicalize the 'handles' option with $handles");
408 sub associate_method{
409 my ($attribute, $method) = @_;
410 $attribute->{associated_methods}++;
414 sub accessor_metaclass(){ 'Mouse::Meta::Method::Accessor' }
416 sub install_accessors{
419 my $metaclass = $attribute->{associated_class};
420 my $accessor_class = $attribute->accessor_metaclass;
422 foreach my $type(qw(accessor reader writer predicate clearer)){
423 if(exists $attribute->{$type}){
424 my $generator = '_generate_' . $type;
425 my $code = $accessor_class->$generator($attribute, $metaclass);
426 $metaclass->add_method($attribute->{$type} => $code);
427 $attribute->associate_method($code);
432 if(exists $attribute->{handles}){
433 my %handles = $attribute->_canonicalize_handles($attribute->{handles});
434 my $reader = $attribute->get_read_method_ref;
436 while(my($handle_name, $method_to_call) = each %handles){
437 my $code = $accessor_class->_generate_delegation($attribute, $metaclass,
438 $reader, $handle_name, $method_to_call);
440 $metaclass->add_method($handle_name => $code);
441 $attribute->associate_method($code);
446 if($attribute->can('create') != \&create){
447 # backword compatibility
448 $attribute->create($metaclass, $attribute->name, %{$attribute});
457 my $metaclass = (ref $self && $self->associated_class) || 'Mouse::Meta::Class';
458 $metaclass->throw_error(@_, depth => 1);
467 Mouse::Meta::Attribute - The Mouse attribute metaclass
471 This document describes Mouse version 0.39
475 =head2 C<< new(%options) -> Mouse::Meta::Attribute >>
477 Instantiates a new Mouse::Meta::Attribute. Does nothing else.
479 It adds the following options to the constructor:
483 =item C<< is => 'ro', 'rw', 'bare' >>
485 This provides a shorthand for specifying the C<reader>, C<writer>, or
486 C<accessor> names. If the attribute is read-only ('ro') then it will
487 have a C<reader> method with the same attribute as the name.
489 If it is read-write ('rw') then it will have an C<accessor> method
490 with the same name. If you provide an explicit C<writer> for a
491 read-write attribute, then you will have a C<reader> with the same
492 name as the attribute, and a C<writer> with the name you provided.
494 Use 'bare' when you are deliberately not installing any methods
495 (accessor, reader, etc.) associated with this attribute; otherwise,
496 Moose will issue a deprecation warning when this attribute is added to a
499 =item C<< isa => Type >>
501 This option accepts a type. The type can be a string, which should be
502 a type name. If the type name is unknown, it is assumed to be a class
505 This option can also accept a L<Moose::Meta::TypeConstraint> object.
507 If you I<also> provide a C<does> option, then your C<isa> option must
508 be a class name, and that class must do the role specified with
511 =item C<< does => Role >>
513 This is short-hand for saying that the attribute's type must be an
514 object which does the named role.
516 B<This option is not yet supported.>
518 =item C<< coerce => Bool >>
520 This option is only valid for objects with a type constraint
521 (C<isa>). If this is true, then coercions will be applied whenever
522 this attribute is set.
524 You can make both this and the C<weak_ref> option true.
526 =item C<< trigger => CodeRef >>
528 This option accepts a subroutine reference, which will be called after
529 the attribute is set.
531 =item C<< required => Bool >>
533 An attribute which is required must be provided to the constructor. An
534 attribute which is required can also have a C<default> or C<builder>,
535 which will satisfy its required-ness.
537 A required attribute must have a C<default>, C<builder> or a
538 non-C<undef> C<init_arg>
540 =item C<< lazy => Bool >>
542 A lazy attribute must have a C<default> or C<builder>. When an
543 attribute is lazy, the default value will not be calculated until the
546 =item C<< weak_ref => Bool >>
548 If this is true, the attribute's value will be stored as a weak
551 =item C<< auto_deref => Bool >>
553 If this is true, then the reader will dereference the value when it is
554 called. The attribute must have a type constraint which defines the
555 attribute as an array or hash reference.
557 =item C<< lazy_build => Bool >>
559 Setting this to true makes the attribute lazy and provides a number of
567 is equivalent to this:
572 builder => '_build_size',
573 clearer => 'clear_size',
574 predicate => 'has_size',
579 =head2 C<< associate_method(Method) >>
581 Associates a method with the attribute. Typically, this is called internally
582 when an attribute generates its accessors.
584 Currently the argument I<Method> is ignored in Mouse.
586 =head2 C<< verify_against_type_constraint(Item) -> TRUE | ERROR >>
588 Checks that the given value passes this attribute's type constraint. Returns C<true>
589 on success, otherwise C<confess>es.
591 =head2 C<< clone_and_inherit_options(options) -> Mouse::Meta::Attribute >>
593 Creates a new attribute in the owner class, inheriting options from parent classes.
594 Accessors and helper methods are installed. Some error checking is done.
596 =head2 C<< get_read_method_ref >>
598 =head2 C<< get_write_method_ref >>
600 Returns the subroutine reference of a method suitable for reading or
601 writing the attribute's value in the associated class. These methods
602 always return a subroutine reference, regardless of whether or not the
603 attribute is read- or write-only.
607 L<Moose::Meta::Attribute>
609 L<Class::MOP::Attribute>