1 package Mouse::Meta::Attribute;
2 use Mouse::Util qw(:meta); # enables strict and warnings
6 use Mouse::Meta::TypeConstraint;
8 #use Mouse::Meta::Method::Accessor;
9 use Mouse::Meta::Method::Delegation;
12 my($class, $name, $args) = @_;
15 # XXX: for backward compatibility (with method modifiers)
16 if($class->can('canonicalize_args') != \&canonicalize_args){
17 %{$args} = $class->canonicalize_args($name, %{$args});
20 # taken from Class::MOP::Attribute::new
23 or $class->throw_error('You must provide a name for the attribute');
25 if(!exists $args->{init_arg}){
26 $args->{init_arg} = $name;
29 # 'required' requires eigher 'init_arg', 'builder', or 'default'
30 my $can_be_required = defined( $args->{init_arg} );
32 if(exists $args->{builder}){
34 # Moose refuses a CODE ref builder, but Mouse doesn't for backward compatibility
35 # This feature will be changed in a future. (gfx)
36 $class->throw_error('builder must be a defined scalar value which is a method name')
37 #if ref $args->{builder} || !defined $args->{builder};
38 if !defined $args->{builder};
42 elsif(exists $args->{default}){
43 if(ref $args->{default} && ref($args->{default}) ne 'CODE'){
44 $class->throw_error("References are not allowed as default values, you must "
45 . "wrap the default of '$name' in a CODE reference (ex: sub { [] } and not [])");
50 if( $args->{required} && !$can_be_required ) {
51 $class->throw_error("You cannot have a required attribute ($name) without a default, builder, or an init_arg");
54 # taken from Mouse::Meta::Attribute->new and _process_args->
56 if(exists $args->{is}){
60 $args->{reader} ||= $name;
63 if(exists $args->{writer}){
64 $args->{reader} ||= $name;
67 $args->{accessor} ||= $name;
71 # do nothing, but don't complain (later) about missing methods
74 $is = 'undef' if !defined $is;
75 $class->throw_error("I do not understand this option (is => $is) on attribute ($name)");
80 if(exists $args->{isa}){
81 $args->{type_constraint} = Mouse::Util::TypeConstraints::find_or_create_isa_type_constraint($args->{isa});
83 elsif(exists $args->{does}){
84 $args->{type_constraint} = Mouse::Util::TypeConstraints::find_or_create_does_type_constraint($args->{does});
86 $tc = $args->{type_constraint};
90 || $class->throw_error("You cannot have coercion without specifying a type constraint on attribute ($name)");
93 && $class->throw_error("You cannot have a weak reference to a coerced value on attribute ($name)");
96 if ($args->{lazy_build}) {
97 exists($args->{default})
98 && $class->throw_error("You can not use lazy_build and default for the same attribute ($name)");
101 $args->{builder} ||= "_build_${name}";
103 $args->{clearer} ||= "_clear${name}";
104 $args->{predicate} ||= "_has${name}";
107 $args->{clearer} ||= "clear_${name}";
108 $args->{predicate} ||= "has_${name}";
112 if ($args->{auto_deref}) {
114 || $class->throw_error("You cannot auto-dereference without specifying a type constraint on attribute ($name)");
116 ( $tc->is_a_type_of('ArrayRef') || $tc->is_a_type_of('HashRef') )
117 || $class->throw_error("You cannot auto-dereference anything other than a ArrayRef or HashRef on attribute ($name)");
120 if (exists $args->{trigger}) {
121 ('CODE' eq ref $args->{trigger})
122 || $class->throw_error("Trigger must be a CODE ref on attribute ($name)");
126 (exists $args->{default} || defined $args->{builder})
127 || $class->throw_error("You cannot have lazy attribute ($name) without specifying a default value for it");
137 my %args = (@_ == 1) ? %{ $_[0] } : @_;
139 $class->_process_options($name, \%args);
143 my $self = bless \%args, $class;
146 if($class ne __PACKAGE__){
147 $class->meta->_initialize_object($self, \%args);
150 # XXX: there is no fast way to check attribute validity
154 # Carp::cluck("Found unknown argument(s) passed to '$name' attribute constructor in '$class': @bad");
160 sub has_read_method { $_[0]->has_reader || $_[0]->has_accessor }
161 sub has_write_method { $_[0]->has_writer || $_[0]->has_accessor }
163 sub _create_args { # DEPRECATED
164 $_[0]->{_create_args} = $_[1] if @_ > 1;
165 $_[0]->{_create_args}
168 sub interpolate_class{
169 my($class, $args) = @_;
171 if(my $metaclass = delete $args->{metaclass}){
172 $class = Mouse::Util::resolve_metaclass_alias( Attribute => $metaclass );
176 if(my $traits_ref = delete $args->{traits}){
178 for (my $i = 0; $i < @{$traits_ref}; $i++) {
179 my $trait = Mouse::Util::resolve_metaclass_alias(Attribute => $traits_ref->[$i], trait => 1);
181 next if $class->does($trait);
183 push @traits, $trait;
186 push @traits, $traits_ref->[++$i]
187 if ref($traits_ref->[$i+1]);
191 $class = Mouse::Meta::Class->create_anon_class(
192 superclasses => [ $class ],
199 return( $class, @traits );
202 sub canonicalize_args{ # DEPRECATED
203 my ($self, $name, %args) = @_;
205 Carp::cluck("$self->canonicalize_args has been deprecated."
206 . "Use \$self->_process_options instead.")
207 if Mouse::Util::_MOUSE_VERBOSE;
212 sub create { # DEPRECATED
213 my ($self, $class, $name, %args) = @_;
215 Carp::cluck("$self->create has been deprecated."
216 . "Use \$meta->add_attribute and \$attr->install_accessors instead.")
217 if Mouse::Util::_MOUSE_VERBOSE;
223 sub _coerce_and_verify {
224 my($self, $value, $instance) = @_;
226 my $type_constraint = $self->{type_constraint};
227 return $value if !defined $type_constraint;
229 if ($self->should_coerce && $type_constraint->has_coercion) {
230 $value = $type_constraint->coerce($value);
233 $self->verify_against_type_constraint($value);
238 sub verify_against_type_constraint {
239 my ($self, $value) = @_;
241 my $type_constraint = $self->{type_constraint};
242 return 1 if !$type_constraint;
243 return 1 if $type_constraint->check($value);
245 $self->verify_type_constraint_error($self->name, $value, $type_constraint);
248 sub verify_type_constraint_error {
249 my($self, $name, $value, $type) = @_;
250 $self->throw_error("Attribute ($name) does not pass the type constraint because: "
251 . $type->get_message($value));
254 sub coerce_constraint { # DEPRECATED
255 my $type = $_[0]->{type_constraint}
258 Carp::cluck("coerce_constraint() has been deprecated, which was an internal utility anyway");
260 return Mouse::Util::TypeConstraints->typecast_constraints($_[0]->associated_class->name, $type, $_[1]);
263 sub clone_and_inherit_options{
264 my($self, %args) = @_;
266 my($attribute_class, @traits) = ref($self)->interpolate_class(\%args);
268 $args{traits} = \@traits if @traits;
269 # do not inherit the 'handles' attribute
270 foreach my $name(keys %{$self}){
271 if(!exists $args{$name} && $name ne 'handles'){
272 $args{$name} = $self->{$name};
275 return $attribute_class->new($self->name, %args);
278 sub clone_parent { # DEPRECATED
282 my %args = ($self->get_parent_args($class, $name), @_);
284 Carp::cluck("$self->clone_parent has been deprecated."
285 . "Use \$meta->add_attribute and \$attr->install_accessors instead.")
286 if Mouse::Util::_MOUSE_VERBOSE;
288 $self->clone_and_inherited_args($class, $name, %args);
291 sub get_parent_args { # DEPRECATED
296 for my $super ($class->linearized_isa) {
297 my $super_attr = $super->can("meta") && $super->meta->get_attribute($name)
299 return %{ $super_attr->_create_args };
302 $self->throw_error("Could not find an attribute by the name of '$name' to inherit from");
306 sub get_read_method {
307 $_[0]->reader || $_[0]->accessor
309 sub get_write_method {
310 $_[0]->writer || $_[0]->accessor
313 sub get_read_method_ref{
316 $self->{_read_method_ref} ||= do{
317 my $metaclass = $self->associated_class
318 or $self->throw_error('No asocciated class for ' . $self->name);
320 my $reader = $self->{reader} || $self->{accessor};
322 $metaclass->name->can($reader);
325 $self->accessor_metaclass->_generate_reader($self, $metaclass);
330 sub get_write_method_ref{
333 $self->{_write_method_ref} ||= do{
334 my $metaclass = $self->associated_class
335 or $self->throw_error('No asocciated class for ' . $self->name);
337 my $reader = $self->{writer} || $self->{accessor};
339 $metaclass->name->can($reader);
342 $self->accessor_metaclass->_generate_writer($self, $metaclass);
347 sub _canonicalize_handles {
348 my($self, $handles) = @_;
350 if (ref($handles) eq 'HASH') {
353 elsif (ref($handles) eq 'ARRAY') {
354 return map { $_ => $_ } @$handles;
356 elsif (ref($handles) eq 'Regexp') {
357 my $class_or_role = ($self->{isa} || $self->{does})
358 || $self->throw_error("Cannot delegate methods based on a Regexp without a type constraint (isa)");
360 my $meta = Mouse::Meta::Class->initialize("$class_or_role"); # "" for stringify
361 return map { $_ => $_ }
362 grep { !Mouse::Object->can($_) && $_ =~ $handles }
363 Mouse::Util::is_a_metarole($meta)
364 ? $meta->get_method_list
365 : $meta->get_all_method_names;
368 $self->throw_error("Unable to canonicalize the 'handles' option with $handles");
372 sub associate_method{
373 my ($attribute, $method_name) = @_;
374 $attribute->{associated_methods}++;
378 sub delegation_metaclass() { 'Mouse::Meta::Method::Delegation' }
380 sub install_accessors{
383 my $metaclass = $attribute->associated_class;
384 my $accessor_class = $attribute->accessor_metaclass;
386 foreach my $type(qw(accessor reader writer predicate clearer)){
387 if(exists $attribute->{$type}){
388 my $generator = '_generate_' . $type;
389 my $code = $accessor_class->$generator($attribute, $metaclass);
390 $metaclass->add_method($attribute->{$type} => $code);
391 $attribute->associate_method($attribute->{$type});
396 if(exists $attribute->{handles}){
397 my $delegation_class = $attribute->delegation_metaclass;
398 my %handles = $attribute->_canonicalize_handles($attribute->{handles});
399 my $reader = $attribute->get_read_method_ref;
401 while(my($handle_name, $method_to_call) = each %handles){
402 my $code = $delegation_class->_generate_delegation($attribute, $metaclass,
403 $reader, $handle_name, $method_to_call);
405 $metaclass->add_method($handle_name => $code);
406 $attribute->associate_method($handle_name);
410 if($attribute->can('create') != \&create){
411 # backword compatibility
412 $attribute->create($metaclass, $attribute->name, %{$attribute});
421 my $metaclass = (ref $self && $self->associated_class) || 'Mouse::Meta::Class';
422 $metaclass->throw_error(@_, depth => 1);
430 Mouse::Meta::Attribute - The Mouse attribute metaclass
434 This document describes Mouse version 0.42
438 =head2 C<< new(%options) -> Mouse::Meta::Attribute >>
440 Instantiates a new Mouse::Meta::Attribute. Does nothing else.
442 It adds the following options to the constructor:
446 =item C<< is => 'ro', 'rw', 'bare' >>
448 This provides a shorthand for specifying the C<reader>, C<writer>, or
449 C<accessor> names. If the attribute is read-only ('ro') then it will
450 have a C<reader> method with the same attribute as the name.
452 If it is read-write ('rw') then it will have an C<accessor> method
453 with the same name. If you provide an explicit C<writer> for a
454 read-write attribute, then you will have a C<reader> with the same
455 name as the attribute, and a C<writer> with the name you provided.
457 Use 'bare' when you are deliberately not installing any methods
458 (accessor, reader, etc.) associated with this attribute; otherwise,
459 Moose will issue a deprecation warning when this attribute is added to a
462 =item C<< isa => Type >>
464 This option accepts a type. The type can be a string, which should be
465 a type name. If the type name is unknown, it is assumed to be a class
468 This option can also accept a L<Moose::Meta::TypeConstraint> object.
470 If you I<also> provide a C<does> option, then your C<isa> option must
471 be a class name, and that class must do the role specified with
474 =item C<< does => Role >>
476 This is short-hand for saying that the attribute's type must be an
477 object which does the named role.
479 B<This option is not yet supported.>
481 =item C<< coerce => Bool >>
483 This option is only valid for objects with a type constraint
484 (C<isa>). If this is true, then coercions will be applied whenever
485 this attribute is set.
487 You can make both this and the C<weak_ref> option true.
489 =item C<< trigger => CodeRef >>
491 This option accepts a subroutine reference, which will be called after
492 the attribute is set.
494 =item C<< required => Bool >>
496 An attribute which is required must be provided to the constructor. An
497 attribute which is required can also have a C<default> or C<builder>,
498 which will satisfy its required-ness.
500 A required attribute must have a C<default>, C<builder> or a
501 non-C<undef> C<init_arg>
503 =item C<< lazy => Bool >>
505 A lazy attribute must have a C<default> or C<builder>. When an
506 attribute is lazy, the default value will not be calculated until the
509 =item C<< weak_ref => Bool >>
511 If this is true, the attribute's value will be stored as a weak
514 =item C<< auto_deref => Bool >>
516 If this is true, then the reader will dereference the value when it is
517 called. The attribute must have a type constraint which defines the
518 attribute as an array or hash reference.
520 =item C<< lazy_build => Bool >>
522 Setting this to true makes the attribute lazy and provides a number of
530 is equivalent to this:
535 builder => '_build_size',
536 clearer => 'clear_size',
537 predicate => 'has_size',
542 =head2 C<< associate_method(MethodName) >>
544 Associates a method with the attribute. Typically, this is called internally
545 when an attribute generates its accessors.
547 Currently the argument I<MethodName> is ignored in Mouse.
549 =head2 C<< verify_against_type_constraint(Item) -> TRUE | ERROR >>
551 Checks that the given value passes this attribute's type constraint. Returns C<true>
552 on success, otherwise C<confess>es.
554 =head2 C<< clone_and_inherit_options(options) -> Mouse::Meta::Attribute >>
556 Creates a new attribute in the owner class, inheriting options from parent classes.
557 Accessors and helper methods are installed. Some error checking is done.
559 =head2 C<< get_read_method_ref >>
561 =head2 C<< get_write_method_ref >>
563 Returns the subroutine reference of a method suitable for reading or
564 writing the attribute's value in the associated class. These methods
565 always return a subroutine reference, regardless of whether or not the
566 attribute is read- or write-only.
570 L<Moose::Meta::Attribute>
572 L<Class::MOP::Attribute>