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 } (
38 # Moose defines, but Mouse doesn't
39 #'definition_context',
42 # special case for AttributeHelpers
47 our @CARP_NOT = qw(Mouse::Meta::Class);
53 my $args = $class->Mouse::Object::BUILDARGS(@_);
55 $class->_process_options($name, $args);
57 $args->{name} = $name;
61 my @bad = grep{ !exists $valid_options{$_} } keys %{$args};
63 # (2) known by subclasses
64 if(@bad && $class ne __PACKAGE__){
68 map { $_->init_arg() }
69 $class->meta->get_all_attributes()
71 @bad = grep{ !exists $valid_attrs{$_} } @bad;
74 # (3) bad options found
77 "Found unknown argument(s) passed to '$name' attribute constructor in '$class': "
78 . Mouse::Util::english_list(@bad));
81 my $self = bless $args, $class;
82 if($class ne __PACKAGE__){
83 $class->meta->_initialize_object($self, $args);
88 sub has_read_method { $_[0]->has_reader || $_[0]->has_accessor }
89 sub has_write_method { $_[0]->has_writer || $_[0]->has_accessor }
91 sub get_read_method { $_[0]->reader || $_[0]->accessor }
92 sub get_write_method { $_[0]->writer || $_[0]->accessor }
94 sub get_read_method_ref{
96 return $self->{_read_method_ref}
97 ||= $self->_get_accessor_method_ref('get_read_method', '_generate_reader');
100 sub get_write_method_ref{
102 return $self->{_write_method_ref}
103 ||= $self->_get_accessor_method_ref('get_write_method', '_generate_writer');
106 sub interpolate_class{
107 my($class, $args) = @_;
109 if(my $metaclass = delete $args->{metaclass}){
110 $class = Mouse::Util::resolve_metaclass_alias( Attribute => $metaclass );
114 if(my $traits_ref = delete $args->{traits}){
116 for (my $i = 0; $i < @{$traits_ref}; $i++) {
117 my $trait = Mouse::Util::resolve_metaclass_alias(Attribute => $traits_ref->[$i], trait => 1);
119 next if $class->does($trait);
121 push @traits, $trait;
124 push @traits, $traits_ref->[++$i]
125 if ref($traits_ref->[$i+1]);
129 $class = Mouse::Meta::Class->create_anon_class(
130 superclasses => [ $class ],
137 return( $class, @traits );
140 sub verify_against_type_constraint {
141 my ($self, $value) = @_;
143 my $type_constraint = $self->{type_constraint};
144 return 1 if !$type_constraint;
145 return 1 if $type_constraint->check($value);
147 $self->_throw_type_constraint_error($value, $type_constraint);
150 sub _throw_type_constraint_error {
151 my($self, $value, $type) = @_;
154 sprintf q{Attribute (%s) does not pass the type constraint because: %s},
156 $type->get_message($value),
160 sub illegal_options_for_inheritance {
161 return qw(reader writer accessor clearer predicate);
164 sub clone_and_inherit_options{
166 my $args = $self->Mouse::Object::BUILDARGS(@_);
168 foreach my $illegal($self->illegal_options_for_inheritance) {
169 if(exists $args->{$illegal} and exists $self->{$illegal}) {
170 $self->throw_error("Illegal inherited option: $illegal");
174 foreach my $name(keys %{$self}){
175 if(!exists $args->{$name}){
176 $args->{$name} = $self->{$name}; # inherit from self
180 my($attribute_class, @traits) = ref($self)->interpolate_class($args);
181 $args->{traits} = \@traits if @traits;
183 # remove temporary caches
184 foreach my $attr(keys %{$args}){
185 if($attr =~ /\A _/xms){
186 delete $args->{$attr};
190 # remove default if lazy_build => 1
191 if($args->{lazy_build}) {
192 delete $args->{default};
195 return $attribute_class->new($self->name, $args);
199 sub _get_accessor_method_ref {
200 my($self, $type, $generator) = @_;
202 my $metaclass = $self->associated_class
203 || $self->throw_error('No asocciated class for ' . $self->name);
205 my $accessor = $self->$type();
207 return $metaclass->get_method_body($accessor);
210 return $self->accessor_metaclass->$generator($self, $metaclass);
215 my($self, $object, $value) = @_;
216 return $self->get_write_method_ref()->($object, $value);
220 my($self, $object) = @_;
221 return $self->get_read_method_ref()->($object);
225 my($self, $object) = @_;
226 my $accessor_ref = $self->{_predicate_ref}
227 ||= $self->_get_accessor_method_ref('predicate', '_generate_predicate');
229 return $accessor_ref->($object);
233 my($self, $object) = @_;
234 my $accessor_ref = $self->{_crealer_ref}
235 ||= $self->_get_accessor_method_ref('clearer', '_generate_clearer');
237 return $accessor_ref->($object);
240 sub associate_method{
241 #my($attribute, $method_name) = @_;
243 $attribute->{associated_methods}++;
247 sub install_accessors{
250 my $metaclass = $attribute->associated_class;
251 my $accessor_class = $attribute->accessor_metaclass;
253 foreach my $type(qw(accessor reader writer predicate clearer)){
254 if(exists $attribute->{$type}){
255 my $generator = '_generate_' . $type;
256 my $code = $accessor_class->$generator($attribute, $metaclass);
257 $metaclass->add_method($attribute->{$type} => $code);
258 $attribute->associate_method($attribute->{$type});
263 if(exists $attribute->{handles}){
264 my %handles = $attribute->_canonicalize_handles();
266 while(my($handle, $method_to_call) = each %handles){
267 if($metaclass->has_method($handle)) {
268 $attribute->throw_error("You cannot overwrite a locally defined method ($handle) with a delegation");
271 $metaclass->add_method($handle =>
272 $attribute->_make_delegation_method(
273 $handle, $method_to_call));
275 $attribute->associate_method($handle);
282 sub delegation_metaclass() { ## no critic
283 'Mouse::Meta::Method::Delegation'
286 sub _canonicalize_handles {
288 my $handles = $self->{handles};
290 my $handle_type = ref $handles;
291 if ($handle_type eq 'HASH') {
294 elsif ($handle_type eq 'ARRAY') {
295 return map { $_ => $_ } @$handles;
297 elsif ($handle_type eq 'Regexp') {
298 my $meta = $self->_find_delegate_metaclass();
299 return map { $_ => $_ }
300 grep { !Mouse::Object->can($_) && $_ =~ $handles }
301 Mouse::Util::is_a_metarole($meta)
302 ? $meta->get_method_list
303 : $meta->get_all_method_names;
305 elsif ($handle_type eq 'CODE') {
306 return $handles->( $self, $self->_find_delegate_metaclass() );
309 $self->throw_error("Unable to canonicalize the 'handles' option with $handles");
313 sub _find_delegate_metaclass {
317 $meta = Mouse::Meta::Class->initialize("$self->{isa}");
319 elsif($self->{does}) {
320 $meta = Mouse::Util::get_metaclass_by_name("$self->{does}");
322 defined($meta) or $self->throw_error(
323 "Cannot find delegate metaclass for attribute " . $self->name);
328 sub _make_delegation_method {
329 my($self, $handle, $method_to_call) = @_;
330 return Mouse::Util::load_class($self->delegation_metaclass)
331 ->_generate_delegation($self, $handle, $method_to_call);
339 Mouse::Meta::Attribute - The Mouse attribute metaclass
343 This document describes Mouse version 0.72
347 This is a meta object protocol for Mouse attributes,
348 which is a subset of Moose::Meta::Attribute.
352 =head2 C<< new(%options) -> Mouse::Meta::Attribute >>
354 Instantiates a new Mouse::Meta::Attribute. Does nothing else.
356 It adds the following options to the constructor:
360 =item C<< is => 'ro', 'rw', 'bare' >>
362 This provides a shorthand for specifying the C<reader>, C<writer>, or
363 C<accessor> names. If the attribute is read-only ('ro') then it will
364 have a C<reader> method with the same attribute as the name.
366 If it is read-write ('rw') then it will have an C<accessor> method
367 with the same name. If you provide an explicit C<writer> for a
368 read-write attribute, then you will have a C<reader> with the same
369 name as the attribute, and a C<writer> with the name you provided.
371 Use 'bare' when you are deliberately not installing any methods
372 (accessor, reader, etc.) associated with this attribute; otherwise,
373 Moose will issue a deprecation warning when this attribute is added to a
376 =item C<< isa => Type >>
378 This option accepts a type. The type can be a string, which should be
379 a type name. If the type name is unknown, it is assumed to be a class
382 This option can also accept a L<Moose::Meta::TypeConstraint> object.
384 If you I<also> provide a C<does> option, then your C<isa> option must
385 be a class name, and that class must do the role specified with
388 =item C<< does => Role >>
390 This is short-hand for saying that the attribute's type must be an
391 object which does the named role.
393 B<This option is not yet supported.>
395 =item C<< coerce => Bool >>
397 This option is only valid for objects with a type constraint
398 (C<isa>). If this is true, then coercions will be applied whenever
399 this attribute is set.
401 You can make both this and the C<weak_ref> option true.
403 =item C<< trigger => CodeRef >>
405 This option accepts a subroutine reference, which will be called after
406 the attribute is set.
408 =item C<< required => Bool >>
410 An attribute which is required must be provided to the constructor. An
411 attribute which is required can also have a C<default> or C<builder>,
412 which will satisfy its required-ness.
414 A required attribute must have a C<default>, C<builder> or a
415 non-C<undef> C<init_arg>
417 =item C<< lazy => Bool >>
419 A lazy attribute must have a C<default> or C<builder>. When an
420 attribute is lazy, the default value will not be calculated until the
423 =item C<< weak_ref => Bool >>
425 If this is true, the attribute's value will be stored as a weak
428 =item C<< auto_deref => Bool >>
430 If this is true, then the reader will dereference the value when it is
431 called. The attribute must have a type constraint which defines the
432 attribute as an array or hash reference.
434 =item C<< lazy_build => Bool >>
436 Setting this to true makes the attribute lazy and provides a number of
444 is equivalent to this:
449 builder => '_build_size',
450 clearer => 'clear_size',
451 predicate => 'has_size',
456 =head2 C<< associate_method(MethodName) >>
458 Associates a method with the attribute. Typically, this is called internally
459 when an attribute generates its accessors.
461 Currently the argument I<MethodName> is ignored in Mouse.
463 =head2 C<< verify_against_type_constraint(Item) -> TRUE | ERROR >>
465 Checks that the given value passes this attribute's type constraint. Returns C<true>
466 on success, otherwise C<confess>es.
468 =head2 C<< clone_and_inherit_options(options) -> Mouse::Meta::Attribute >>
470 Creates a new attribute in the owner class, inheriting options from parent classes.
471 Accessors and helper methods are installed. Some error checking is done.
473 =head2 C<< get_read_method_ref >>
475 =head2 C<< get_write_method_ref >>
477 Returns the subroutine reference of a method suitable for reading or
478 writing the attribute's value in the associated class. These methods
479 always return a subroutine reference, regardless of whether or not the
480 attribute is read- or write-only.
484 L<Moose::Meta::Attribute>
486 L<Class::MOP::Attribute>