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");
159 sub has_read_method { $_[0]->has_reader || $_[0]->has_accessor }
160 sub has_write_method { $_[0]->has_writer || $_[0]->has_accessor }
162 sub _create_args { # DEPRECATED
163 $_[0]->{_create_args} = $_[1] if @_ > 1;
164 $_[0]->{_create_args}
167 sub interpolate_class{
168 my($class, $args) = @_;
170 if(my $metaclass = delete $args->{metaclass}){
171 $class = Mouse::Util::resolve_metaclass_alias( Attribute => $metaclass );
175 if(my $traits_ref = delete $args->{traits}){
177 for (my $i = 0; $i < @{$traits_ref}; $i++) {
178 my $trait = Mouse::Util::resolve_metaclass_alias(Attribute => $traits_ref->[$i], trait => 1);
180 next if $class->does($trait);
182 push @traits, $trait;
185 push @traits, $traits_ref->[++$i]
186 if ref($traits_ref->[$i+1]);
190 $class = Mouse::Meta::Class->create_anon_class(
191 superclasses => [ $class ],
198 return( $class, @traits );
201 sub canonicalize_args{ # DEPRECATED
202 my ($self, $name, %args) = @_;
204 Carp::cluck("$self->canonicalize_args has been deprecated."
205 . "Use \$self->_process_options instead.")
211 sub create { # DEPRECATED
212 my ($self, $class, $name, %args) = @_;
214 Carp::cluck("$self->create has been deprecated."
215 . "Use \$meta->add_attribute and \$attr->install_accessors instead.")
222 sub _coerce_and_verify {
223 my($self, $value, $instance) = @_;
225 my $type_constraint = $self->{type_constraint};
226 return $value if !defined $type_constraint;
228 if ($self->should_coerce && $type_constraint->has_coercion) {
229 $value = $type_constraint->coerce($value);
232 $self->verify_against_type_constraint($value);
237 sub verify_against_type_constraint {
238 my ($self, $value) = @_;
240 my $type_constraint = $self->{type_constraint};
241 return 1 if !$type_constraint;
242 return 1 if $type_constraint->check($value);
244 $self->verify_type_constraint_error($self->name, $value, $type_constraint);
247 sub verify_type_constraint_error {
248 my($self, $name, $value, $type) = @_;
249 $self->throw_error("Attribute ($name) does not pass the type constraint because: "
250 . $type->get_message($value));
253 sub coerce_constraint { # DEPRECATED
254 my $type = $_[0]->{type_constraint}
257 Carp::cluck("coerce_constraint() has been deprecated, which was an internal utility anyway");
259 return Mouse::Util::TypeConstraints->typecast_constraints($_[0]->associated_class->name, $type, $_[1]);
262 sub clone_and_inherit_options{
263 my($self, %args) = @_;
265 my($attribute_class, @traits) = ref($self)->interpolate_class(\%args);
267 $args{traits} = \@traits if @traits;
268 return $attribute_class->new($self->name, %{$self}, %args);
271 sub clone_parent { # DEPRECATED
275 my %args = ($self->get_parent_args($class, $name), @_);
277 Carp::cluck("$self->clone_parent has been deprecated."
278 . "Use \$meta->add_attribute and \$attr->install_accessors instead.")
281 $self->clone_and_inherited_args($class, $name, %args);
284 sub get_parent_args { # DEPRECATED
289 for my $super ($class->linearized_isa) {
290 my $super_attr = $super->can("meta") && $super->meta->get_attribute($name)
292 return %{ $super_attr->_create_args };
295 $self->throw_error("Could not find an attribute by the name of '$name' to inherit from");
299 sub get_read_method {
300 $_[0]->reader || $_[0]->accessor
302 sub get_write_method {
303 $_[0]->writer || $_[0]->accessor
306 sub get_read_method_ref{
309 $self->{_read_method_ref} ||= do{
310 my $metaclass = $self->associated_class
311 or $self->throw_error('No asocciated class for ' . $self->name);
313 my $reader = $self->{reader} || $self->{accessor};
315 $metaclass->name->can($reader);
318 $self->accessor_metaclass->_generate_reader($self, $metaclass);
323 sub get_write_method_ref{
326 $self->{_write_method_ref} ||= do{
327 my $metaclass = $self->associated_class
328 or $self->throw_error('No asocciated class for ' . $self->name);
330 my $reader = $self->{writer} || $self->{accessor};
332 $metaclass->name->can($reader);
335 $self->accessor_metaclass->_generate_writer($self, $metaclass);
340 sub _canonicalize_handles {
341 my($self, $handles) = @_;
343 if (ref($handles) eq 'HASH') {
346 elsif (ref($handles) eq 'ARRAY') {
347 return map { $_ => $_ } @$handles;
349 elsif (ref($handles) eq 'Regexp') {
350 my $class_or_role = ($self->{isa} || $self->{does})
351 || $self->throw_error("Cannot delegate methods based on a Regexp without a type constraint (isa)");
353 my $meta = Mouse::Meta::Class->initialize("$class_or_role"); # "" for stringify
354 return map { $_ => $_ }
355 grep { $_ ne 'meta' && !Mouse::Object->can($_) && $_ =~ $handles }
356 $meta->isa('Mouse::Meta::Class') ? $meta->get_all_method_names : $meta->get_method_list;
359 $self->throw_error("Unable to canonicalize the 'handles' option with $handles");
363 sub associate_method{
364 my ($attribute, $method) = @_;
365 $attribute->{associated_methods}++;
369 sub install_accessors{
372 my $metaclass = $attribute->associated_class;
373 my $accessor_class = $attribute->accessor_metaclass;
375 foreach my $type(qw(accessor reader writer predicate clearer)){
376 if(exists $attribute->{$type}){
377 my $generator = '_generate_' . $type;
378 my $code = $accessor_class->$generator($attribute, $metaclass);
379 $metaclass->add_method($attribute->{$type} => $code);
380 $attribute->associate_method($code);
385 if(exists $attribute->{handles}){
386 my %handles = $attribute->_canonicalize_handles($attribute->{handles});
387 my $reader = $attribute->get_read_method_ref;
389 while(my($handle_name, $method_to_call) = each %handles){
390 my $code = $accessor_class->_generate_delegation($attribute, $metaclass,
391 $reader, $handle_name, $method_to_call);
393 $metaclass->add_method($handle_name => $code);
394 $attribute->associate_method($code);
399 if($attribute->can('create') != \&create){
400 # backword compatibility
401 $attribute->create($metaclass, $attribute->name, %{$attribute});
410 my $metaclass = (ref $self && $self->associated_class) || 'Mouse::Meta::Class';
411 $metaclass->throw_error(@_, depth => 1);
420 Mouse::Meta::Attribute - The Mouse attribute metaclass
424 This document describes Mouse version 0.40_01
428 =head2 C<< new(%options) -> Mouse::Meta::Attribute >>
430 Instantiates a new Mouse::Meta::Attribute. Does nothing else.
432 It adds the following options to the constructor:
436 =item C<< is => 'ro', 'rw', 'bare' >>
438 This provides a shorthand for specifying the C<reader>, C<writer>, or
439 C<accessor> names. If the attribute is read-only ('ro') then it will
440 have a C<reader> method with the same attribute as the name.
442 If it is read-write ('rw') then it will have an C<accessor> method
443 with the same name. If you provide an explicit C<writer> for a
444 read-write attribute, then you will have a C<reader> with the same
445 name as the attribute, and a C<writer> with the name you provided.
447 Use 'bare' when you are deliberately not installing any methods
448 (accessor, reader, etc.) associated with this attribute; otherwise,
449 Moose will issue a deprecation warning when this attribute is added to a
452 =item C<< isa => Type >>
454 This option accepts a type. The type can be a string, which should be
455 a type name. If the type name is unknown, it is assumed to be a class
458 This option can also accept a L<Moose::Meta::TypeConstraint> object.
460 If you I<also> provide a C<does> option, then your C<isa> option must
461 be a class name, and that class must do the role specified with
464 =item C<< does => Role >>
466 This is short-hand for saying that the attribute's type must be an
467 object which does the named role.
469 B<This option is not yet supported.>
471 =item C<< coerce => Bool >>
473 This option is only valid for objects with a type constraint
474 (C<isa>). If this is true, then coercions will be applied whenever
475 this attribute is set.
477 You can make both this and the C<weak_ref> option true.
479 =item C<< trigger => CodeRef >>
481 This option accepts a subroutine reference, which will be called after
482 the attribute is set.
484 =item C<< required => Bool >>
486 An attribute which is required must be provided to the constructor. An
487 attribute which is required can also have a C<default> or C<builder>,
488 which will satisfy its required-ness.
490 A required attribute must have a C<default>, C<builder> or a
491 non-C<undef> C<init_arg>
493 =item C<< lazy => Bool >>
495 A lazy attribute must have a C<default> or C<builder>. When an
496 attribute is lazy, the default value will not be calculated until the
499 =item C<< weak_ref => Bool >>
501 If this is true, the attribute's value will be stored as a weak
504 =item C<< auto_deref => Bool >>
506 If this is true, then the reader will dereference the value when it is
507 called. The attribute must have a type constraint which defines the
508 attribute as an array or hash reference.
510 =item C<< lazy_build => Bool >>
512 Setting this to true makes the attribute lazy and provides a number of
520 is equivalent to this:
525 builder => '_build_size',
526 clearer => 'clear_size',
527 predicate => 'has_size',
532 =head2 C<< associate_method(Method) >>
534 Associates a method with the attribute. Typically, this is called internally
535 when an attribute generates its accessors.
537 Currently the argument I<Method> is ignored in Mouse.
539 =head2 C<< verify_against_type_constraint(Item) -> TRUE | ERROR >>
541 Checks that the given value passes this attribute's type constraint. Returns C<true>
542 on success, otherwise C<confess>es.
544 =head2 C<< clone_and_inherit_options(options) -> Mouse::Meta::Attribute >>
546 Creates a new attribute in the owner class, inheriting options from parent classes.
547 Accessors and helper methods are installed. Some error checking is done.
549 =head2 C<< get_read_method_ref >>
551 =head2 C<< get_write_method_ref >>
553 Returns the subroutine reference of a method suitable for reading or
554 writing the attribute's value in the associated class. These methods
555 always return a subroutine reference, regardless of whether or not the
556 attribute is read- or write-only.
560 L<Moose::Meta::Attribute>
562 L<Class::MOP::Attribute>