1 package Mouse::Meta::Attribute;
2 use Mouse::Util qw(:meta); # enables strict and warnings
6 use Mouse::Meta::TypeConstraint;
9 my($class, $name, $args) = @_;
11 # XXX: for backward compatibility (with method modifiers)
12 if($class->can('canonicalize_args') != \&canonicalize_args){
13 %{$args} = $class->canonicalize_args($name, %{$args});
16 # taken from Class::MOP::Attribute::new
19 or $class->throw_error('You must provide a name for the attribute');
21 if(!exists $args->{init_arg}){
22 $args->{init_arg} = $name;
25 # 'required' requires eigher 'init_arg', 'builder', or 'default'
26 my $can_be_required = defined( $args->{init_arg} );
28 if(exists $args->{builder}){
30 # Moose refuses a CODE ref builder, but Mouse doesn't for backward compatibility
31 # This feature will be changed in a future. (gfx)
32 $class->throw_error('builder must be a defined scalar value which is a method name')
33 #if ref $args->{builder} || !defined $args->{builder};
34 if !defined $args->{builder};
38 elsif(exists $args->{default}){
39 if(ref $args->{default} && ref($args->{default}) ne 'CODE'){
40 $class->throw_error("References are not allowed as default values, you must "
41 . "wrap the default of '$name' in a CODE reference (ex: sub { [] } and not [])");
46 if( $args->{required} && !$can_be_required ) {
47 $class->throw_error("You cannot have a required attribute ($name) without a default, builder, or an init_arg");
50 # taken from Mouse::Meta::Attribute->new and _process_args->
52 if(exists $args->{is}){
56 $args->{reader} ||= $name;
59 if(exists $args->{writer}){
60 $args->{reader} ||= $name;
63 $args->{accessor} ||= $name;
67 # do nothing, but don't complain (later) about missing methods
70 $is = 'undef' if !defined $is;
71 $class->throw_error("I do not understand this option (is => $is) on attribute ($name)");
76 if(exists $args->{isa}){
77 $args->{type_constraint} = Mouse::Util::TypeConstraints::find_or_create_isa_type_constraint($args->{isa});
79 elsif(exists $args->{does}){
80 $args->{type_constraint} = Mouse::Util::TypeConstraints::find_or_create_does_type_constraint($args->{does});
82 $tc = $args->{type_constraint};
86 || $class->throw_error("You cannot have coercion without specifying a type constraint on attribute ($name)");
89 && $class->throw_error("You cannot have a weak reference to a coerced value on attribute ($name)");
92 if ($args->{lazy_build}) {
93 exists($args->{default})
94 && $class->throw_error("You can not use lazy_build and default for the same attribute ($name)");
97 $args->{builder} ||= "_build_${name}";
99 $args->{clearer} ||= "_clear${name}";
100 $args->{predicate} ||= "_has${name}";
103 $args->{clearer} ||= "clear_${name}";
104 $args->{predicate} ||= "has_${name}";
108 if ($args->{auto_deref}) {
110 || $class->throw_error("You cannot auto-dereference without specifying a type constraint on attribute ($name)");
112 ( $tc->is_a_type_of('ArrayRef') || $tc->is_a_type_of('HashRef') )
113 || $class->throw_error("You cannot auto-dereference anything other than a ArrayRef or HashRef on attribute ($name)");
116 if (exists $args->{trigger}) {
117 ('CODE' eq ref $args->{trigger})
118 || $class->throw_error("Trigger must be a CODE ref on attribute ($name)");
122 (exists $args->{default} || defined $args->{builder})
123 || $class->throw_error("You cannot have lazy attribute ($name) without specifying a default value for it");
133 my %args = (@_ == 1) ? %{ $_[0] } : @_;
135 $class->_process_options($name, \%args);
139 my $self = bless \%args, $class;
142 if($class ne __PACKAGE__){
143 $class->meta->_initialize_object($self, \%args);
146 # XXX: there is no fast way to check attribute validity
150 # Carp::cluck("Found unknown argument(s) passed to '$name' attribute constructor in '$class': @bad");
156 sub has_read_method { $_[0]->has_reader || $_[0]->has_accessor }
157 sub has_write_method { $_[0]->has_writer || $_[0]->has_accessor }
159 sub _create_args { # DEPRECATED
160 $_[0]->{_create_args} = $_[1] if @_ > 1;
161 $_[0]->{_create_args}
164 sub interpolate_class{
165 my($class, $args) = @_;
167 if(my $metaclass = delete $args->{metaclass}){
168 $class = Mouse::Util::resolve_metaclass_alias( Attribute => $metaclass );
172 if(my $traits_ref = delete $args->{traits}){
174 for (my $i = 0; $i < @{$traits_ref}; $i++) {
175 my $trait = Mouse::Util::resolve_metaclass_alias(Attribute => $traits_ref->[$i], trait => 1);
177 next if $class->does($trait);
179 push @traits, $trait;
182 push @traits, $traits_ref->[++$i]
183 if ref($traits_ref->[$i+1]);
187 $class = Mouse::Meta::Class->create_anon_class(
188 superclasses => [ $class ],
195 return( $class, @traits );
198 sub canonicalize_args{ # DEPRECATED
199 my ($self, $name, %args) = @_;
201 Carp::cluck("$self->canonicalize_args has been deprecated."
202 . "Use \$self->_process_options instead.");
207 sub create { # DEPRECATED
208 my ($self, $class, $name, %args) = @_;
210 Carp::cluck("$self->create has been deprecated."
211 . "Use \$meta->add_attribute and \$attr->install_accessors instead.");
217 sub _coerce_and_verify {
218 my($self, $value, $instance) = @_;
220 my $type_constraint = $self->{type_constraint};
221 return $value if !defined $type_constraint;
223 if ($self->should_coerce && $type_constraint->has_coercion) {
224 $value = $type_constraint->coerce($value);
227 $self->verify_against_type_constraint($value);
232 sub verify_against_type_constraint {
233 my ($self, $value) = @_;
235 my $type_constraint = $self->{type_constraint};
236 return 1 if !$type_constraint;
237 return 1 if $type_constraint->check($value);
239 $self->_throw_type_constraint_error($value, $type_constraint);
242 sub _throw_type_constraint_error {
243 my($self, $value, $type) = @_;
246 sprintf q{Attribute (%s) does not pass the type constraint because: %s},
248 $type->get_message($value),
252 sub clone_and_inherit_options{
253 my($self, %args) = @_;
255 my($attribute_class, @traits) = ref($self)->interpolate_class(\%args);
257 $args{traits} = \@traits if @traits;
258 # do not inherit the 'handles' attribute
259 foreach my $name(keys %{$self}){
260 if(!exists $args{$name} && $name ne 'handles'){
261 $args{$name} = $self->{$name};
264 return $attribute_class->new($self->name, %args);
267 sub clone_parent { # DEPRECATED
271 my %args = ($self->get_parent_args($class, $name), @_);
273 Carp::cluck("$self->clone_parent has been deprecated."
274 . "Use \$meta->add_attribute and \$attr->install_accessors instead.");
276 $self->clone_and_inherited_args($class, $name, %args);
279 sub get_parent_args { # DEPRECATED
284 for my $super ($class->linearized_isa) {
285 my $super_attr = $super->can("meta") && $super->meta->get_attribute($name)
287 return %{ $super_attr->_create_args };
290 $self->throw_error("Could not find an attribute by the name of '$name' to inherit from");
294 sub get_read_method {
295 return $_[0]->reader || $_[0]->accessor
297 sub get_write_method {
298 return $_[0]->writer || $_[0]->accessor
301 sub _get_accessor_method_ref {
302 my($self, $type, $generator) = @_;
304 my $metaclass = $self->associated_class
305 || $self->throw_error('No asocciated class for ' . $self->name);
307 my $accessor = $self->$type();
309 return $metaclass->get_method_body($accessor);
312 return $self->accessor_metaclass->$generator($self, $metaclass);
316 sub get_read_method_ref{
318 return $self->{_read_method_ref} ||= $self->_get_accessor_method_ref('get_read_method', '_generate_reader');
321 sub get_write_method_ref{
323 return $self->{_write_method_ref} ||= $self->_get_accessor_method_ref('get_write_method', '_generate_writer');
327 my($self, $object, $value) = @_;
328 return $self->get_write_method_ref()->($object, $value);
332 my($self, $object) = @_;
333 return $self->get_read_method_ref()->($object);
337 my($self, $object) = @_;
338 my $accessor_ref = $self->{_predicate_ref}
339 ||= $self->_get_accessor_method_ref('predicate', '_generate_predicate');
341 return $accessor_ref->($object);
345 my($self, $object) = @_;
346 my $accessor_ref = $self->{_crealer_ref}
347 ||= $self->_get_accessor_method_ref('clearer', '_generate_clearer');
349 return $accessor_ref->($object);
353 sub associate_method{
354 my ($attribute, $method_name) = @_;
355 $attribute->{associated_methods}++;
359 sub install_accessors{
362 my $metaclass = $attribute->associated_class;
363 my $accessor_class = $attribute->accessor_metaclass;
365 foreach my $type(qw(accessor reader writer predicate clearer)){
366 if(exists $attribute->{$type}){
367 my $generator = '_generate_' . $type;
368 my $code = $accessor_class->$generator($attribute, $metaclass);
369 $metaclass->add_method($attribute->{$type} => $code);
370 $attribute->associate_method($attribute->{$type});
375 if(exists $attribute->{handles}){
376 my %handles = $attribute->_canonicalize_handles($attribute->{handles});
378 while(my($handle, $method_to_call) = each %handles){
379 $metaclass->add_method($handle =>
380 $attribute->_make_delegation_method(
381 $handle, $method_to_call));
383 $attribute->associate_method($handle);
387 if($attribute->can('create') != \&create){
388 # backword compatibility
389 $attribute->create($metaclass, $attribute->name, %{$attribute});
395 sub delegation_metaclass() { 'Mouse::Meta::Method::Delegation' }
397 sub _canonicalize_handles {
398 my($self, $handles) = @_;
400 if (ref($handles) eq 'HASH') {
403 elsif (ref($handles) eq 'ARRAY') {
404 return map { $_ => $_ } @$handles;
406 elsif ( ref($handles) eq 'CODE' ) {
407 my $class_or_role = ( $self->{isa} || $self->{does} )
408 || $self->throw_error( "Cannot find delegate metaclass for attribute " . $self->name );
409 return $handles->( $self, Mouse::Meta::Class->initialize("$class_or_role"));
411 elsif (ref($handles) eq 'Regexp') {
412 my $class_or_role = ($self->{isa} || $self->{does})
413 || $self->throw_error("Cannot delegate methods based on a Regexp without a type constraint (isa)");
415 my $meta = Mouse::Meta::Class->initialize("$class_or_role"); # "" for stringify
416 return map { $_ => $_ }
417 grep { !Mouse::Object->can($_) && $_ =~ $handles }
418 Mouse::Util::is_a_metarole($meta)
419 ? $meta->get_method_list
420 : $meta->get_all_method_names;
423 $self->throw_error("Unable to canonicalize the 'handles' option with $handles");
427 sub _make_delegation_method {
428 my($self, $handle, $method_to_call) = @_;
429 my $delegator = $self->delegation_metaclass;
430 Mouse::Util::load_class($delegator);
432 return $delegator->_generate_delegation($self, $handle, $method_to_call);
438 my $metaclass = (ref $self && $self->associated_class) || 'Mouse::Meta::Class';
439 $metaclass->throw_error(@_, depth => 1);
447 Mouse::Meta::Attribute - The Mouse attribute metaclass
451 This document describes Mouse version 0.46
455 =head2 C<< new(%options) -> Mouse::Meta::Attribute >>
457 Instantiates a new Mouse::Meta::Attribute. Does nothing else.
459 It adds the following options to the constructor:
463 =item C<< is => 'ro', 'rw', 'bare' >>
465 This provides a shorthand for specifying the C<reader>, C<writer>, or
466 C<accessor> names. If the attribute is read-only ('ro') then it will
467 have a C<reader> method with the same attribute as the name.
469 If it is read-write ('rw') then it will have an C<accessor> method
470 with the same name. If you provide an explicit C<writer> for a
471 read-write attribute, then you will have a C<reader> with the same
472 name as the attribute, and a C<writer> with the name you provided.
474 Use 'bare' when you are deliberately not installing any methods
475 (accessor, reader, etc.) associated with this attribute; otherwise,
476 Moose will issue a deprecation warning when this attribute is added to a
479 =item C<< isa => Type >>
481 This option accepts a type. The type can be a string, which should be
482 a type name. If the type name is unknown, it is assumed to be a class
485 This option can also accept a L<Moose::Meta::TypeConstraint> object.
487 If you I<also> provide a C<does> option, then your C<isa> option must
488 be a class name, and that class must do the role specified with
491 =item C<< does => Role >>
493 This is short-hand for saying that the attribute's type must be an
494 object which does the named role.
496 B<This option is not yet supported.>
498 =item C<< coerce => Bool >>
500 This option is only valid for objects with a type constraint
501 (C<isa>). If this is true, then coercions will be applied whenever
502 this attribute is set.
504 You can make both this and the C<weak_ref> option true.
506 =item C<< trigger => CodeRef >>
508 This option accepts a subroutine reference, which will be called after
509 the attribute is set.
511 =item C<< required => Bool >>
513 An attribute which is required must be provided to the constructor. An
514 attribute which is required can also have a C<default> or C<builder>,
515 which will satisfy its required-ness.
517 A required attribute must have a C<default>, C<builder> or a
518 non-C<undef> C<init_arg>
520 =item C<< lazy => Bool >>
522 A lazy attribute must have a C<default> or C<builder>. When an
523 attribute is lazy, the default value will not be calculated until the
526 =item C<< weak_ref => Bool >>
528 If this is true, the attribute's value will be stored as a weak
531 =item C<< auto_deref => Bool >>
533 If this is true, then the reader will dereference the value when it is
534 called. The attribute must have a type constraint which defines the
535 attribute as an array or hash reference.
537 =item C<< lazy_build => Bool >>
539 Setting this to true makes the attribute lazy and provides a number of
547 is equivalent to this:
552 builder => '_build_size',
553 clearer => 'clear_size',
554 predicate => 'has_size',
559 =head2 C<< associate_method(MethodName) >>
561 Associates a method with the attribute. Typically, this is called internally
562 when an attribute generates its accessors.
564 Currently the argument I<MethodName> is ignored in Mouse.
566 =head2 C<< verify_against_type_constraint(Item) -> TRUE | ERROR >>
568 Checks that the given value passes this attribute's type constraint. Returns C<true>
569 on success, otherwise C<confess>es.
571 =head2 C<< clone_and_inherit_options(options) -> Mouse::Meta::Attribute >>
573 Creates a new attribute in the owner class, inheriting options from parent classes.
574 Accessors and helper methods are installed. Some error checking is done.
576 =head2 C<< get_read_method_ref >>
578 =head2 C<< get_write_method_ref >>
580 Returns the subroutine reference of a method suitable for reading or
581 writing the attribute's value in the associated class. These methods
582 always return a subroutine reference, regardless of whether or not the
583 attribute is read- or write-only.
587 L<Moose::Meta::Attribute>
589 L<Class::MOP::Attribute>