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) = @_;
15 # taken from Class::MOP::Attribute::new
18 or $class->throw_error('You must provide a name for the attribute');
20 if(!exists $args->{init_arg}){
21 $args->{init_arg} = $name;
24 # 'required' requires eigher 'init_arg', 'builder', or 'default'
25 my $can_be_required = defined( $args->{init_arg} );
27 if(exists $args->{builder}){
28 $class->throw_error('builder must be a defined scalar value which is a method name')
29 if ref $args->{builder} || !(defined $args->{builder});
33 elsif(exists $args->{default}){
34 if(ref $args->{default} && ref($args->{default}) ne 'CODE'){
35 $class->throw_error("References are not allowed as default values, you must "
36 . "wrap the default of '$name' in a CODE reference (ex: sub { [] } and not [])");
41 if( $args->{required} && !$can_be_required ) {
42 $class->throw_error("You cannot have a required attribute ($name) without a default, builder, or an init_arg");
45 # taken from Mouse::Meta::Attribute->new and _process_args->
47 if(exists $args->{is}){
51 $args->{reader} ||= $name;
54 if(exists $args->{writer}){
55 $args->{reader} ||= $name;
58 $args->{accessor} ||= $name;
62 # do nothing, but don't complain (later) about missing methods
65 $is = 'undef' if !defined $is;
66 $class->throw_error("I do not understand this option (is => $is) on attribute ($name)");
71 if(exists $args->{isa}){
72 $args->{type_constraint} = Mouse::Util::TypeConstraints::find_or_create_isa_type_constraint($args->{isa});
74 elsif(exists $args->{does}){
75 $args->{type_constraint} = Mouse::Util::TypeConstraints::find_or_create_does_type_constraint($args->{does});
77 $tc = $args->{type_constraint};
81 || $class->throw_error("You cannot have coercion without specifying a type constraint on attribute ($name)");
84 && $class->throw_error("You cannot have a weak reference to a coerced value on attribute ($name)");
87 if ($args->{lazy_build}) {
88 exists($args->{default})
89 && $class->throw_error("You can not use lazy_build and default for the same attribute ($name)");
92 $args->{builder} ||= "_build_${name}";
94 $args->{clearer} ||= "_clear${name}";
95 $args->{predicate} ||= "_has${name}";
98 $args->{clearer} ||= "clear_${name}";
99 $args->{predicate} ||= "has_${name}";
103 if ($args->{auto_deref}) {
105 || $class->throw_error("You cannot auto-dereference without specifying a type constraint on attribute ($name)");
107 ( $tc->is_a_type_of('ArrayRef') || $tc->is_a_type_of('HashRef') )
108 || $class->throw_error("You cannot auto-dereference anything other than a ArrayRef or HashRef on attribute ($name)");
111 if (exists $args->{trigger}) {
112 ('CODE' eq ref $args->{trigger})
113 || $class->throw_error("Trigger must be a CODE ref on attribute ($name)");
117 (exists $args->{default} || defined $args->{builder})
118 || $class->throw_error("You cannot have lazy attribute ($name) without specifying a default value for it");
121 # XXX: for backward compatibility (with method modifiers)
122 if($class->can('canonicalize_args') != \&canonicalize_args){
123 %{$args} = $class->canonicalize_args($name, %{$args});
132 my %args = (@_ == 1) ? %{ $_[0] } : @_;
134 $class->_process_options($name, \%args);
138 my $instance = bless \%args, $class;
141 if($class ne __PACKAGE__){
142 $class->meta->_initialize_instance($instance,\%args);
145 # XXX: there is no fast way to check attribute validity
149 # Carp::cluck("Found unknown argument(s) passed to '$name' attribute constructor in '$class': @bad");
157 sub name { $_[0]->{name} }
158 sub associated_class { $_[0]->{associated_class} }
160 sub accessor { $_[0]->{accessor} }
161 sub reader { $_[0]->{reader} }
162 sub writer { $_[0]->{writer} }
163 sub predicate { $_[0]->{predicate} }
164 sub clearer { $_[0]->{clearer} }
165 sub handles { $_[0]->{handles} }
167 sub _is_metadata { $_[0]->{is} }
168 sub is_required { $_[0]->{required} }
169 sub default { $_[0]->{default} }
170 sub is_lazy { $_[0]->{lazy} }
171 sub is_lazy_build { $_[0]->{lazy_build} }
172 sub is_weak_ref { $_[0]->{weak_ref} }
173 sub init_arg { $_[0]->{init_arg} }
174 sub type_constraint { $_[0]->{type_constraint} }
176 sub trigger { $_[0]->{trigger} }
177 sub builder { $_[0]->{builder} }
178 sub should_auto_deref { $_[0]->{auto_deref} }
179 sub should_coerce { $_[0]->{coerce} }
181 sub get_read_method { $_[0]->{reader} || $_[0]->{accessor} }
182 sub get_write_method { $_[0]->{writer} || $_[0]->{accessor} }
186 sub has_accessor { exists $_[0]->{accessor} }
187 sub has_reader { exists $_[0]->{reader} }
188 sub has_writer { exists $_[0]->{writer} }
189 sub has_predicate { exists $_[0]->{predicate} }
190 sub has_clearer { exists $_[0]->{clearer} }
191 sub has_handles { exists $_[0]->{handles} }
193 sub has_default { exists $_[0]->{default} }
194 sub has_type_constraint { exists $_[0]->{type_constraint} }
195 sub has_trigger { exists $_[0]->{trigger} }
196 sub has_builder { exists $_[0]->{builder} }
198 sub has_read_method { exists $_[0]->{reader} || exists $_[0]->{accessor} }
199 sub has_write_method { exists $_[0]->{writer} || exists $_[0]->{accessor} }
202 $_[0]->{_create_args} = $_[1] if @_ > 1;
203 $_[0]->{_create_args}
206 sub accessor_metaclass { 'Mouse::Meta::Method::Accessor' }
208 sub interpolate_class{
209 my($class, $name, $args) = @_;
211 if(my $metaclass = delete $args->{metaclass}){
212 $class = Mouse::Util::resolve_metaclass_alias( Attribute => $metaclass );
216 if(my $traits_ref = delete $args->{traits}){
218 for (my $i = 0; $i < @{$traits_ref}; $i++) {
219 my $trait = Mouse::Util::resolve_metaclass_alias(Attribute => $traits_ref->[$i], trait => 1);
221 next if $class->does($trait);
223 push @traits, $trait;
226 push @traits, $traits_ref->[++$i]
227 if ref($traits_ref->[$i+1]);
231 $class = Mouse::Meta::Class->create_anon_class(
232 superclasses => [ $class ],
239 return( $class, @traits );
242 sub canonicalize_args{
243 my ($self, $name, %args) = @_;
245 Carp::cluck("$self->canonicalize_args has been deprecated."
246 . "Use \$self->_process_options instead.");
252 my ($self, $class, $name, %args) = @_;
254 Carp::cluck("$self->create has been deprecated."
255 . "Use \$meta->add_attribute and \$attr->install_accessors instead.");
261 sub verify_against_type_constraint {
262 my ($self, $value) = @_;
263 my $tc = $self->type_constraint;
267 return 1 if $tc->check($value);
269 $self->verify_type_constraint_error($self->name, $value, $tc);
272 sub verify_type_constraint_error {
273 my($self, $name, $value, $type) = @_;
274 $self->throw_error("Attribute ($name) does not pass the type constraint because: " . $type->get_message($value));
277 sub coerce_constraint { ## my($self, $value) = @_;
278 my $type = $_[0]->{type_constraint}
280 return Mouse::Util::TypeConstraints->typecast_constraints($_[0]->associated_class->name, $_[0]->type_constraint, $_[1]);
283 sub _canonicalize_handles {
287 if (ref($handles) eq 'HASH') {
290 elsif (ref($handles) eq 'ARRAY') {
291 return map { $_ => $_ } @$handles;
294 $self->throw_error("Unable to canonicalize the 'handles' option with $handles");
298 sub clone_and_inherit_options{
302 return ref($self)->new($name, %{$self}, @_ == 1 ? %{$_[0]} : @_);
309 my %args = ($self->get_parent_args($class, $name), @_);
311 Carp::cluck("$self->clone_parent has been deprecated."
312 . "Use \$meta->add_attribute and \$attr->install_accessors instead.");
315 $self->create($class, $name, %args);
318 sub get_parent_args {
323 for my $super ($class->linearized_isa) {
324 my $super_attr = $super->can("meta") && $super->meta->get_attribute($name)
326 return %{ $super_attr->_create_args };
329 $self->throw_error("Could not find an attribute by the name of '$name' to inherit from");
332 sub install_accessors{
335 my $metaclass = $attribute->{associated_class};
336 my $generator_class = $attribute->accessor_metaclass;
338 foreach my $type(qw(accessor reader writer predicate clearer handles)){
339 if(exists $attribute->{$type}){
340 my $installer = '_install_' . $type;
341 $generator_class->$installer($attribute, $attribute->{$type}, $metaclass);
342 $attribute->{associated_methods}++;
346 if($attribute->can('create') != \&create){
347 $attribute->create($metaclass, $attribute->name, %{$attribute});
356 my $metaclass = (ref $self && $self->associated_class) || 'Mouse::Meta::Class';
357 $metaclass->throw_error(@_, depth => 1);
366 Mouse::Meta::Attribute - attribute metaclass
370 =head2 C<< new(%options) -> Mouse::Meta::Attribute >>
372 Instantiates a new Mouse::Meta::Attribute. Does nothing else.
374 It adds the following options to the constructor:
378 =item * C<< is => 'ro', 'rw', 'bare' >>
380 This provides a shorthand for specifying the C<reader>, C<writer>, or
381 C<accessor> names. If the attribute is read-only ('ro') then it will
382 have a C<reader> method with the same attribute as the name.
384 If it is read-write ('rw') then it will have an C<accessor> method
385 with the same name. If you provide an explicit C<writer> for a
386 read-write attribute, then you will have a C<reader> with the same
387 name as the attribute, and a C<writer> with the name you provided.
389 Use 'bare' when you are deliberately not installing any methods
390 (accessor, reader, etc.) associated with this attribute; otherwise,
391 Moose will issue a deprecation warning when this attribute is added to a
394 =item * C<< isa => Type >>
396 This option accepts a type. The type can be a string, which should be
397 a type name. If the type name is unknown, it is assumed to be a class
400 This option can also accept a L<Moose::Meta::TypeConstraint> object.
402 If you I<also> provide a C<does> option, then your C<isa> option must
403 be a class name, and that class must do the role specified with
406 =item * C<< does => Role >>
408 This is short-hand for saying that the attribute's type must be an
409 object which does the named role.
411 B<This option is not yet supported.>
413 =item * C<< coerce => Bool >>
415 This option is only valid for objects with a type constraint
416 (C<isa>). If this is true, then coercions will be applied whenever
417 this attribute is set.
419 You can make both this and the C<weak_ref> option true.
421 =item * C<< trigger => CodeRef >>
423 This option accepts a subroutine reference, which will be called after
424 the attribute is set.
426 =item * C<< required => Bool >>
428 An attribute which is required must be provided to the constructor. An
429 attribute which is required can also have a C<default> or C<builder>,
430 which will satisfy its required-ness.
432 A required attribute must have a C<default>, C<builder> or a
433 non-C<undef> C<init_arg>
435 =item * C<< lazy => Bool >>
437 A lazy attribute must have a C<default> or C<builder>. When an
438 attribute is lazy, the default value will not be calculated until the
441 =item * C<< weak_ref => Bool >>
443 If this is true, the attribute's value will be stored as a weak
446 =item * C<< auto_deref => Bool >>
448 If this is true, then the reader will dereference the value when it is
449 called. The attribute must have a type constraint which defines the
450 attribute as an array or hash reference.
452 =item * C<< lazy_build => Bool >>
454 Setting this to true makes the attribute lazy and provides a number of
462 is equivalent to this:
467 builder => '_build_size',
468 clearer => 'clear_size',
469 predicate => 'has_size',
474 =head2 C<< verify_against_type_constraint(Item) -> TRUE | ERROR >>
476 Checks that the given value passes this attribute's type constraint. Returns C<true>
477 on success, otherwise C<confess>es.
479 =head2 C<< clone_and_inherit_options(options) -> Mouse::Meta::Attribute >>
481 Creates a new attribute in OwnerClass, inheriting options from parent classes.
482 Accessors and helper methods are installed. Some error checking is done.
486 L<Moose::Meta::Attribute>