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;
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}){
85 $args->{type_constraint} = Mouse::Util::TypeConstraints::find_or_create_does_type_constraint($args->{does});
87 $tc = $args->{type_constraint};
91 || $class->throw_error("You cannot have coercion without specifying a type constraint on attribute ($name)");
94 && $class->throw_error("You cannot have a weak reference to a coerced value on attribute ($name)");
97 if ($args->{lazy_build}) {
98 exists($args->{default})
99 && $class->throw_error("You can not use lazy_build and default for the same attribute ($name)");
102 $args->{builder} ||= "_build_${name}";
104 $args->{clearer} ||= "_clear${name}";
105 $args->{predicate} ||= "_has${name}";
108 $args->{clearer} ||= "clear_${name}";
109 $args->{predicate} ||= "has_${name}";
113 if ($args->{auto_deref}) {
115 || $class->throw_error("You cannot auto-dereference without specifying a type constraint on attribute ($name)");
117 ( $tc->is_a_type_of('ArrayRef') || $tc->is_a_type_of('HashRef') )
118 || $class->throw_error("You cannot auto-dereference anything other than a ArrayRef or HashRef on attribute ($name)");
121 if (exists $args->{trigger}) {
122 ('CODE' eq ref $args->{trigger})
123 || $class->throw_error("Trigger must be a CODE ref on attribute ($name)");
127 (exists $args->{default} || defined $args->{builder})
128 || $class->throw_error("You cannot have lazy attribute ($name) without specifying a default value for it");
138 my %args = (@_ == 1) ? %{ $_[0] } : @_;
140 $class->_process_options($name, \%args);
144 my $self = bless \%args, $class;
147 if($class ne __PACKAGE__){
148 $class->meta->_initialize_object($self, \%args);
151 # XXX: there is no fast way to check attribute validity
155 # Carp::cluck("Found unknown argument(s) passed to '$name' attribute constructor in '$class': @bad");
161 sub has_read_method { $_[0]->has_reader || $_[0]->has_accessor }
162 sub has_write_method { $_[0]->has_writer || $_[0]->has_accessor }
164 sub _create_args { # DEPRECATED
165 $_[0]->{_create_args} = $_[1] if @_ > 1;
166 $_[0]->{_create_args}
169 sub interpolate_class{
170 my($class, $args) = @_;
172 if(my $metaclass = delete $args->{metaclass}){
173 $class = Mouse::Util::resolve_metaclass_alias( Attribute => $metaclass );
177 if(my $traits_ref = delete $args->{traits}){
179 for (my $i = 0; $i < @{$traits_ref}; $i++) {
180 my $trait = Mouse::Util::resolve_metaclass_alias(Attribute => $traits_ref->[$i], trait => 1);
182 next if $class->does($trait);
184 push @traits, $trait;
187 push @traits, $traits_ref->[++$i]
188 if ref($traits_ref->[$i+1]);
192 $class = Mouse::Meta::Class->create_anon_class(
193 superclasses => [ $class ],
200 return( $class, @traits );
203 sub canonicalize_args{ # DEPRECATED
204 my ($self, $name, %args) = @_;
206 Carp::cluck("$self->canonicalize_args has been deprecated."
207 . "Use \$self->_process_options instead.")
213 sub create { # DEPRECATED
214 my ($self, $class, $name, %args) = @_;
216 Carp::cluck("$self->create has been deprecated."
217 . "Use \$meta->add_attribute and \$attr->install_accessors instead.")
224 sub _coerce_and_verify {
225 my($self, $value, $instance) = @_;
227 my $type_constraint = $self->{type_constraint};
228 return $value if !defined $type_constraint;
230 if ($self->should_coerce && $type_constraint->has_coercion) {
231 $value = $type_constraint->coerce($value);
234 $self->verify_against_type_constraint($value);
239 sub verify_against_type_constraint {
240 my ($self, $value) = @_;
242 my $type_constraint = $self->{type_constraint};
243 return 1 if !$type_constraint;
244 return 1 if $type_constraint->check($value);
246 $self->verify_type_constraint_error($self->name, $value, $type_constraint);
249 sub verify_type_constraint_error {
250 my($self, $name, $value, $type) = @_;
251 $self->throw_error("Attribute ($name) does not pass the type constraint because: "
252 . $type->get_message($value));
255 sub coerce_constraint { # DEPRECATED
256 my $type = $_[0]->{type_constraint}
259 Carp::cluck("coerce_constraint() has been deprecated, which was an internal utility anyway");
261 return Mouse::Util::TypeConstraints->typecast_constraints($_[0]->associated_class->name, $type, $_[1]);
264 sub clone_and_inherit_options{
265 my($self, %args) = @_;
267 my($attribute_class, @traits) = ref($self)->interpolate_class(\%args);
269 $args{traits} = \@traits if @traits;
270 # do not inherit the 'handles' attribute
271 foreach my $name(keys %{$self}){
272 if(!exists $args{$name} && $name ne 'handles'){
273 $args{$name} = $self->{$name};
276 return $attribute_class->new($self->name, %args);
279 sub clone_parent { # DEPRECATED
283 my %args = ($self->get_parent_args($class, $name), @_);
285 Carp::cluck("$self->clone_parent has been deprecated."
286 . "Use \$meta->add_attribute and \$attr->install_accessors instead.")
289 $self->clone_and_inherited_args($class, $name, %args);
292 sub get_parent_args { # DEPRECATED
297 for my $super ($class->linearized_isa) {
298 my $super_attr = $super->can("meta") && $super->meta->get_attribute($name)
300 return %{ $super_attr->_create_args };
303 $self->throw_error("Could not find an attribute by the name of '$name' to inherit from");
307 sub get_read_method {
308 $_[0]->reader || $_[0]->accessor
310 sub get_write_method {
311 $_[0]->writer || $_[0]->accessor
314 sub get_read_method_ref{
317 $self->{_read_method_ref} ||= do{
318 my $metaclass = $self->associated_class
319 or $self->throw_error('No asocciated class for ' . $self->name);
321 my $reader = $self->{reader} || $self->{accessor};
323 $metaclass->name->can($reader);
326 $self->accessor_metaclass->_generate_reader($self, $metaclass);
331 sub get_write_method_ref{
334 $self->{_write_method_ref} ||= do{
335 my $metaclass = $self->associated_class
336 or $self->throw_error('No asocciated class for ' . $self->name);
338 my $reader = $self->{writer} || $self->{accessor};
340 $metaclass->name->can($reader);
343 $self->accessor_metaclass->_generate_writer($self, $metaclass);
348 sub _canonicalize_handles {
349 my($self, $handles) = @_;
351 if (ref($handles) eq 'HASH') {
354 elsif (ref($handles) eq 'ARRAY') {
355 return map { $_ => $_ } @$handles;
357 elsif (ref($handles) eq 'Regexp') {
358 my $class_or_role = ($self->{isa} || $self->{does})
359 || $self->throw_error("Cannot delegate methods based on a Regexp without a type constraint (isa)");
361 my $meta = Mouse::Meta::Class->initialize("$class_or_role"); # "" for stringify
362 return map { $_ => $_ }
363 grep { $_ ne 'meta' && !Mouse::Object->can($_) && $_ =~ $handles }
364 Mouse::Util::TypeConstraints::_is_a_metarole($meta)
365 ? $meta->get_method_list
366 : $meta->get_all_method_names;
369 $self->throw_error("Unable to canonicalize the 'handles' option with $handles");
373 sub associate_method{
374 my ($attribute, $method) = @_;
375 $attribute->{associated_methods}++;
380 sub delegation_metaclass() { 'Mouse::Meta::Method::Delegation' }
382 sub install_accessors{
385 my $metaclass = $attribute->associated_class;
386 my $accessor_class = $attribute->accessor_metaclass;
388 foreach my $type(qw(accessor reader writer predicate clearer)){
389 if(exists $attribute->{$type}){
390 my $generator = '_generate_' . $type;
391 my $code = $accessor_class->$generator($attribute, $metaclass);
392 $metaclass->add_method($attribute->{$type} => $code);
393 $attribute->associate_method($code);
398 if(exists $attribute->{handles}){
399 my $delegation_class = $attribute->delegation_metaclass;
400 my %handles = $attribute->_canonicalize_handles($attribute->{handles});
401 my $reader = $attribute->get_read_method_ref;
403 while(my($handle_name, $method_to_call) = each %handles){
404 my $code = $delegation_class->_generate_delegation($attribute, $metaclass,
405 $reader, $handle_name, $method_to_call);
407 $metaclass->add_method($handle_name => $code);
408 $attribute->associate_method($code);
413 if($attribute->can('create') != \&create){
414 # backword compatibility
415 $attribute->create($metaclass, $attribute->name, %{$attribute});
424 my $metaclass = (ref $self && $self->associated_class) || 'Mouse::Meta::Class';
425 $metaclass->throw_error(@_, depth => 1);
434 Mouse::Meta::Attribute - The Mouse attribute metaclass
438 This document describes Mouse version 0.40_01
442 =head2 C<< new(%options) -> Mouse::Meta::Attribute >>
444 Instantiates a new Mouse::Meta::Attribute. Does nothing else.
446 It adds the following options to the constructor:
450 =item C<< is => 'ro', 'rw', 'bare' >>
452 This provides a shorthand for specifying the C<reader>, C<writer>, or
453 C<accessor> names. If the attribute is read-only ('ro') then it will
454 have a C<reader> method with the same attribute as the name.
456 If it is read-write ('rw') then it will have an C<accessor> method
457 with the same name. If you provide an explicit C<writer> for a
458 read-write attribute, then you will have a C<reader> with the same
459 name as the attribute, and a C<writer> with the name you provided.
461 Use 'bare' when you are deliberately not installing any methods
462 (accessor, reader, etc.) associated with this attribute; otherwise,
463 Moose will issue a deprecation warning when this attribute is added to a
466 =item C<< isa => Type >>
468 This option accepts a type. The type can be a string, which should be
469 a type name. If the type name is unknown, it is assumed to be a class
472 This option can also accept a L<Moose::Meta::TypeConstraint> object.
474 If you I<also> provide a C<does> option, then your C<isa> option must
475 be a class name, and that class must do the role specified with
478 =item C<< does => Role >>
480 This is short-hand for saying that the attribute's type must be an
481 object which does the named role.
483 B<This option is not yet supported.>
485 =item C<< coerce => Bool >>
487 This option is only valid for objects with a type constraint
488 (C<isa>). If this is true, then coercions will be applied whenever
489 this attribute is set.
491 You can make both this and the C<weak_ref> option true.
493 =item C<< trigger => CodeRef >>
495 This option accepts a subroutine reference, which will be called after
496 the attribute is set.
498 =item C<< required => Bool >>
500 An attribute which is required must be provided to the constructor. An
501 attribute which is required can also have a C<default> or C<builder>,
502 which will satisfy its required-ness.
504 A required attribute must have a C<default>, C<builder> or a
505 non-C<undef> C<init_arg>
507 =item C<< lazy => Bool >>
509 A lazy attribute must have a C<default> or C<builder>. When an
510 attribute is lazy, the default value will not be calculated until the
513 =item C<< weak_ref => Bool >>
515 If this is true, the attribute's value will be stored as a weak
518 =item C<< auto_deref => Bool >>
520 If this is true, then the reader will dereference the value when it is
521 called. The attribute must have a type constraint which defines the
522 attribute as an array or hash reference.
524 =item C<< lazy_build => Bool >>
526 Setting this to true makes the attribute lazy and provides a number of
534 is equivalent to this:
539 builder => '_build_size',
540 clearer => 'clear_size',
541 predicate => 'has_size',
546 =head2 C<< associate_method(Method) >>
548 Associates a method with the attribute. Typically, this is called internally
549 when an attribute generates its accessors.
551 Currently the argument I<Method> is ignored in Mouse.
553 =head2 C<< verify_against_type_constraint(Item) -> TRUE | ERROR >>
555 Checks that the given value passes this attribute's type constraint. Returns C<true>
556 on success, otherwise C<confess>es.
558 =head2 C<< clone_and_inherit_options(options) -> Mouse::Meta::Attribute >>
560 Creates a new attribute in the owner class, inheriting options from parent classes.
561 Accessors and helper methods are installed. Some error checking is done.
563 =head2 C<< get_read_method_ref >>
565 =head2 C<< get_write_method_ref >>
567 Returns the subroutine reference of a method suitable for reading or
568 writing the attribute's value in the associated class. These methods
569 always return a subroutine reference, regardless of whether or not the
570 attribute is read- or write-only.
574 L<Moose::Meta::Attribute>
576 L<Class::MOP::Attribute>