1 package Mouse::Meta::Attribute;
2 use Mouse::Util qw(:meta); # enables strict and warnings
6 use Mouse::Meta::TypeConstraint;
8 my %valid_options = map { $_ => undef } (
37 # Moose defines, but Mouse doesn't
38 #'definition_context',
42 # special case for AttributeHelpers
47 our @CARP_NOT = qw(Mouse::Meta::Class);
53 my $args = $class->Mouse::Object::BUILDARGS(@_);
55 # XXX: for backward compatibility (with method modifiers)
56 if($class->can('canonicalize_args') != \&canonicalize_args){
57 %{$args} = $class->canonicalize_args($name, %{$args});
60 $class->_process_options($name, $args);
62 $args->{name} = $name;
66 my @bad = grep{ !exists $valid_options{$_} } keys %{$args};
68 # (2) known by subclasses
69 if(@bad && $class ne __PACKAGE__){
73 map { $_->init_arg() }
74 $class->meta->get_all_attributes()
76 @bad = grep{ !exists $valid_attrs{$_} } @bad;
79 # (3) bad options found
82 "Found unknown argument(s) passed to '$name' attribute constructor in '$class': "
83 . Mouse::Util::english_list(@bad));
86 my $self = bless $args, $class;
89 if($class ne __PACKAGE__){
90 $class->meta->_initialize_object($self, $args);
96 sub has_read_method { $_[0]->has_reader || $_[0]->has_accessor }
97 sub has_write_method { $_[0]->has_writer || $_[0]->has_accessor }
99 sub _create_args { # DEPRECATED
100 $_[0]->{_create_args} = $_[1] if @_ > 1;
101 $_[0]->{_create_args}
104 sub interpolate_class{
105 my($class, $args) = @_;
107 if(my $metaclass = delete $args->{metaclass}){
108 $class = Mouse::Util::resolve_metaclass_alias( Attribute => $metaclass );
112 if(my $traits_ref = delete $args->{traits}){
114 for (my $i = 0; $i < @{$traits_ref}; $i++) {
115 my $trait = Mouse::Util::resolve_metaclass_alias(Attribute => $traits_ref->[$i], trait => 1);
117 next if $class->does($trait);
119 push @traits, $trait;
122 push @traits, $traits_ref->[++$i]
123 if ref($traits_ref->[$i+1]);
127 $class = Mouse::Meta::Class->create_anon_class(
128 superclasses => [ $class ],
135 return( $class, @traits );
138 sub canonicalize_args{ # DEPRECATED
139 my ($self, $name, %args) = @_;
141 Carp::cluck("$self->canonicalize_args has been deprecated."
142 . "Use \$self->_process_options instead.");
147 sub create { # DEPRECATED
148 my ($self, $class, $name, %args) = @_;
150 Carp::cluck("$self->create has been deprecated."
151 . "Use \$meta->add_attribute and \$attr->install_accessors instead.");
157 sub _coerce_and_verify {
158 my($self, $value, $instance) = @_;
160 my $type_constraint = $self->{type_constraint};
161 return $value if !defined $type_constraint;
163 if ($self->should_coerce && $type_constraint->has_coercion) {
164 $value = $type_constraint->coerce($value);
167 $self->verify_against_type_constraint($value);
172 sub verify_against_type_constraint {
173 my ($self, $value) = @_;
175 my $type_constraint = $self->{type_constraint};
176 return 1 if !$type_constraint;
177 return 1 if $type_constraint->check($value);
179 $self->_throw_type_constraint_error($value, $type_constraint);
182 sub _throw_type_constraint_error {
183 my($self, $value, $type) = @_;
186 sprintf q{Attribute (%s) does not pass the type constraint because: %s},
188 $type->get_message($value),
192 sub clone_and_inherit_options{
194 my $args = $self->Mouse::Object::BUILDARGS(@_);
196 my($attribute_class, @traits) = ref($self)->interpolate_class($args);
198 $args->{traits} = \@traits if @traits;
199 # do not inherit the 'handles' attribute
200 foreach my $name(keys %{$self}){
201 if(!exists $args->{$name} && $name ne 'handles'){
202 $args->{$name} = $self->{$name};
206 # remove temporary caches
207 foreach my $attr(keys %{$args}){
208 if($attr =~ /\A _/xms){
209 delete $args->{$attr};
213 return $attribute_class->new($self->name, $args);
216 sub clone_parent { # DEPRECATED
220 my %args = ($self->get_parent_args($class, $name), @_);
222 Carp::cluck("$self->clone_parent has been deprecated."
223 . "Use \$meta->add_attribute and \$attr->install_accessors instead.");
225 $self->clone_and_inherited_args($class, $name, %args);
228 sub get_parent_args { # DEPRECATED
233 for my $super ($class->linearized_isa) {
234 my $super_attr = $super->can("meta") && $super->meta->get_attribute($name)
236 return %{ $super_attr->_create_args };
239 $self->throw_error("Could not find an attribute by the name of '$name' to inherit from");
243 sub get_read_method {
244 return $_[0]->reader || $_[0]->accessor
246 sub get_write_method {
247 return $_[0]->writer || $_[0]->accessor
250 sub _get_accessor_method_ref {
251 my($self, $type, $generator) = @_;
253 my $metaclass = $self->associated_class
254 || $self->throw_error('No asocciated class for ' . $self->name);
256 my $accessor = $self->$type();
258 return $metaclass->get_method_body($accessor);
261 return $self->accessor_metaclass->$generator($self, $metaclass);
265 sub get_read_method_ref{
267 return $self->{_read_method_ref} ||= $self->_get_accessor_method_ref('get_read_method', '_generate_reader');
270 sub get_write_method_ref{
272 return $self->{_write_method_ref} ||= $self->_get_accessor_method_ref('get_write_method', '_generate_writer');
276 my($self, $object, $value) = @_;
277 return $self->get_write_method_ref()->($object, $value);
281 my($self, $object) = @_;
282 return $self->get_read_method_ref()->($object);
286 my($self, $object) = @_;
287 my $accessor_ref = $self->{_predicate_ref}
288 ||= $self->_get_accessor_method_ref('predicate', '_generate_predicate');
290 return $accessor_ref->($object);
294 my($self, $object) = @_;
295 my $accessor_ref = $self->{_crealer_ref}
296 ||= $self->_get_accessor_method_ref('clearer', '_generate_clearer');
298 return $accessor_ref->($object);
302 sub associate_method{
303 my ($attribute, $method_name) = @_;
304 $attribute->{associated_methods}++;
308 sub install_accessors{
311 my $metaclass = $attribute->associated_class;
312 my $accessor_class = $attribute->accessor_metaclass;
314 foreach my $type(qw(accessor reader writer predicate clearer)){
315 if(exists $attribute->{$type}){
316 my $generator = '_generate_' . $type;
317 my $code = $accessor_class->$generator($attribute, $metaclass);
318 $metaclass->add_method($attribute->{$type} => $code);
319 $attribute->associate_method($attribute->{$type});
324 if(exists $attribute->{handles}){
325 my %handles = $attribute->_canonicalize_handles($attribute->{handles});
327 while(my($handle, $method_to_call) = each %handles){
328 $metaclass->add_method($handle =>
329 $attribute->_make_delegation_method(
330 $handle, $method_to_call));
332 $attribute->associate_method($handle);
336 if($attribute->can('create') != \&create){
337 # backword compatibility
338 $attribute->create($metaclass, $attribute->name, %{$attribute});
344 sub delegation_metaclass() { 'Mouse::Meta::Method::Delegation' }
346 sub _canonicalize_handles {
347 my($self, $handles) = @_;
349 if (ref($handles) eq 'HASH') {
352 elsif (ref($handles) eq 'ARRAY') {
353 return map { $_ => $_ } @$handles;
355 elsif ( ref($handles) eq 'CODE' ) {
356 my $class_or_role = ( $self->{isa} || $self->{does} )
357 || $self->throw_error( "Cannot find delegate metaclass for attribute " . $self->name );
358 return $handles->( $self, Mouse::Meta::Class->initialize("$class_or_role"));
360 elsif (ref($handles) eq 'Regexp') {
361 my $class_or_role = ($self->{isa} || $self->{does})
362 || $self->throw_error("Cannot delegate methods based on a Regexp without a type constraint (isa)");
364 my $meta = Mouse::Meta::Class->initialize("$class_or_role"); # "" for stringify
365 return map { $_ => $_ }
366 grep { !Mouse::Object->can($_) && $_ =~ $handles }
367 Mouse::Util::is_a_metarole($meta)
368 ? $meta->get_method_list
369 : $meta->get_all_method_names;
372 $self->throw_error("Unable to canonicalize the 'handles' option with $handles");
376 sub _make_delegation_method {
377 my($self, $handle, $method_to_call) = @_;
378 return Mouse::Util::load_class($self->delegation_metaclass)
379 ->_generate_delegation($self, $handle, $method_to_call);
385 my $metaclass = (ref $self && $self->associated_class) || 'Mouse::Meta::Class';
386 $metaclass->throw_error(@_, depth => 1);
394 Mouse::Meta::Attribute - The Mouse attribute metaclass
398 This document describes Mouse version 0.50_07
402 =head2 C<< new(%options) -> Mouse::Meta::Attribute >>
404 Instantiates a new Mouse::Meta::Attribute. Does nothing else.
406 It adds the following options to the constructor:
410 =item C<< is => 'ro', 'rw', 'bare' >>
412 This provides a shorthand for specifying the C<reader>, C<writer>, or
413 C<accessor> names. If the attribute is read-only ('ro') then it will
414 have a C<reader> method with the same attribute as the name.
416 If it is read-write ('rw') then it will have an C<accessor> method
417 with the same name. If you provide an explicit C<writer> for a
418 read-write attribute, then you will have a C<reader> with the same
419 name as the attribute, and a C<writer> with the name you provided.
421 Use 'bare' when you are deliberately not installing any methods
422 (accessor, reader, etc.) associated with this attribute; otherwise,
423 Moose will issue a deprecation warning when this attribute is added to a
426 =item C<< isa => Type >>
428 This option accepts a type. The type can be a string, which should be
429 a type name. If the type name is unknown, it is assumed to be a class
432 This option can also accept a L<Moose::Meta::TypeConstraint> object.
434 If you I<also> provide a C<does> option, then your C<isa> option must
435 be a class name, and that class must do the role specified with
438 =item C<< does => Role >>
440 This is short-hand for saying that the attribute's type must be an
441 object which does the named role.
443 B<This option is not yet supported.>
445 =item C<< coerce => Bool >>
447 This option is only valid for objects with a type constraint
448 (C<isa>). If this is true, then coercions will be applied whenever
449 this attribute is set.
451 You can make both this and the C<weak_ref> option true.
453 =item C<< trigger => CodeRef >>
455 This option accepts a subroutine reference, which will be called after
456 the attribute is set.
458 =item C<< required => Bool >>
460 An attribute which is required must be provided to the constructor. An
461 attribute which is required can also have a C<default> or C<builder>,
462 which will satisfy its required-ness.
464 A required attribute must have a C<default>, C<builder> or a
465 non-C<undef> C<init_arg>
467 =item C<< lazy => Bool >>
469 A lazy attribute must have a C<default> or C<builder>. When an
470 attribute is lazy, the default value will not be calculated until the
473 =item C<< weak_ref => Bool >>
475 If this is true, the attribute's value will be stored as a weak
478 =item C<< auto_deref => Bool >>
480 If this is true, then the reader will dereference the value when it is
481 called. The attribute must have a type constraint which defines the
482 attribute as an array or hash reference.
484 =item C<< lazy_build => Bool >>
486 Setting this to true makes the attribute lazy and provides a number of
494 is equivalent to this:
499 builder => '_build_size',
500 clearer => 'clear_size',
501 predicate => 'has_size',
506 =head2 C<< associate_method(MethodName) >>
508 Associates a method with the attribute. Typically, this is called internally
509 when an attribute generates its accessors.
511 Currently the argument I<MethodName> is ignored in Mouse.
513 =head2 C<< verify_against_type_constraint(Item) -> TRUE | ERROR >>
515 Checks that the given value passes this attribute's type constraint. Returns C<true>
516 on success, otherwise C<confess>es.
518 =head2 C<< clone_and_inherit_options(options) -> Mouse::Meta::Attribute >>
520 Creates a new attribute in the owner class, inheriting options from parent classes.
521 Accessors and helper methods are installed. Some error checking is done.
523 =head2 C<< get_read_method_ref >>
525 =head2 C<< get_write_method_ref >>
527 Returns the subroutine reference of a method suitable for reading or
528 writing the attribute's value in the associated class. These methods
529 always return a subroutine reference, regardless of whether or not the
530 attribute is read- or write-only.
534 L<Moose::Meta::Attribute>
536 L<Class::MOP::Attribute>