1 package Mouse::Meta::Attribute;
2 use Mouse::Util qw(:meta); # enables strict and warnings
6 use Mouse::Meta::TypeConstraint;
9 # name init_arg required
12 # accessor reader writer predicate clearer
13 # default builder lazy lazy_build
24 my($class, $name, $args) = @_;
26 # taken from Class::MOP::Attribute::new
29 or $class->throw_error('You must provide a name for the attribute');
31 if(!exists $args->{init_arg}){
32 $args->{init_arg} = $name;
35 # 'required' requires eigher 'init_arg', 'builder', or 'default'
36 my $can_be_required = defined( $args->{init_arg} );
38 if(exists $args->{builder}){
40 # Moose refuses a CODE ref builder, but Mouse doesn't for backward compatibility
41 # This feature will be changed in a future. (gfx)
42 $class->throw_error('builder must be a defined scalar value which is a method name')
43 #if ref $args->{builder} || !defined $args->{builder};
44 if !defined $args->{builder};
48 elsif(exists $args->{default}){
49 if(ref $args->{default} && ref($args->{default}) ne 'CODE'){
50 $class->throw_error("References are not allowed as default values, you must "
51 . "wrap the default of '$name' in a CODE reference (ex: sub { [] } and not [])");
56 if( $args->{required} && !$can_be_required ) {
57 $class->throw_error("You cannot have a required attribute ($name) without a default, builder, or an init_arg");
60 # taken from Mouse::Meta::Attribute->new and _process_args->
62 if(exists $args->{is}){
66 $args->{reader} ||= $name;
69 if(exists $args->{writer}){
70 $args->{reader} ||= $name;
73 $args->{accessor} ||= $name;
77 # do nothing, but don't complain (later) about missing methods
80 $is = 'undef' if !defined $is;
81 $class->throw_error("I do not understand this option (is => $is) on attribute ($name)");
86 if(exists $args->{isa}){
87 $args->{type_constraint} = Mouse::Util::TypeConstraints::find_or_create_isa_type_constraint($args->{isa});
89 elsif(exists $args->{does}){
90 $args->{type_constraint} = Mouse::Util::TypeConstraints::find_or_create_does_type_constraint($args->{does});
92 $tc = $args->{type_constraint};
96 || $class->throw_error("You cannot have coercion without specifying a type constraint on attribute ($name)");
99 && $class->throw_error("You cannot have a weak reference to a coerced value on attribute ($name)");
102 if ($args->{lazy_build}) {
103 exists($args->{default})
104 && $class->throw_error("You can not use lazy_build and default for the same attribute ($name)");
107 $args->{builder} ||= "_build_${name}";
109 $args->{clearer} ||= "_clear${name}";
110 $args->{predicate} ||= "_has${name}";
113 $args->{clearer} ||= "clear_${name}";
114 $args->{predicate} ||= "has_${name}";
118 if ($args->{auto_deref}) {
120 || $class->throw_error("You cannot auto-dereference without specifying a type constraint on attribute ($name)");
122 ( $tc->is_a_type_of('ArrayRef') || $tc->is_a_type_of('HashRef') )
123 || $class->throw_error("You cannot auto-dereference anything other than a ArrayRef or HashRef on attribute ($name)");
126 if (exists $args->{trigger}) {
127 ('CODE' eq ref $args->{trigger})
128 || $class->throw_error("Trigger must be a CODE ref on attribute ($name)");
132 (exists $args->{default} || defined $args->{builder})
133 || $class->throw_error("You cannot have lazy attribute ($name) without specifying a default value for it");
143 my %args = (@_ == 1) ? %{ $_[0] } : @_;
145 $class->_process_options($name, \%args);
149 my $self = bless \%args, $class;
152 if($class ne __PACKAGE__){
153 $class->meta->_initialize_object($self, \%args);
156 # XXX: there is no fast way to check attribute validity
160 # Carp::cluck("Found unknown argument(s) passed to '$name' attribute constructor in '$class': @bad");
166 sub has_read_method { $_[0]->has_reader || $_[0]->has_accessor }
167 sub has_write_method { $_[0]->has_writer || $_[0]->has_accessor }
169 sub interpolate_class{
170 my($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( $class, @traits );
203 sub _coerce_and_verify {
204 my($self, $value, $instance) = @_;
206 my $type_constraint = $self->{type_constraint};
207 return $value if !defined $type_constraint;
209 if ($self->should_coerce && $type_constraint->has_coercion) {
210 $value = $type_constraint->coerce($value);
213 $self->verify_against_type_constraint($value);
218 sub verify_against_type_constraint {
219 my ($self, $value) = @_;
221 my $type_constraint = $self->{type_constraint};
222 return 1 if !$type_constraint;
223 return 1 if $type_constraint->check($value);
225 $self->_throw_type_constraint_error($value, $type_constraint);
228 sub _throw_type_constraint_error {
229 my($self, $value, $type) = @_;
232 sprintf q{Attribute (%s) does not pass the type constraint because: %s},
234 $type->get_message($value),
238 sub clone_and_inherit_options{
239 my($self, %args) = @_;
241 my($attribute_class, @traits) = ref($self)->interpolate_class(\%args);
243 $args{traits} = \@traits if @traits;
244 # do not inherit the 'handles' attribute
245 foreach my $name(keys %{$self}){
246 if(!exists $args{$name} && $name ne 'handles'){
247 $args{$name} = $self->{$name};
250 return $attribute_class->new($self->name, %args);
253 sub get_read_method {
254 return $_[0]->reader || $_[0]->accessor
256 sub get_write_method {
257 return $_[0]->writer || $_[0]->accessor
260 sub _get_accessor_method_ref {
261 my($self, $type, $generator) = @_;
263 my $metaclass = $self->associated_class
264 || $self->throw_error('No asocciated class for ' . $self->name);
266 my $accessor = $self->$type();
268 return $metaclass->get_method_body($accessor);
271 return $self->accessor_metaclass->$generator($self, $metaclass);
275 sub get_read_method_ref{
277 return $self->{_read_method_ref} ||= $self->_get_accessor_method_ref('get_read_method', '_generate_reader');
280 sub get_write_method_ref{
282 return $self->{_write_method_ref} ||= $self->_get_accessor_method_ref('get_write_method', '_generate_writer');
286 my($self, $object, $value) = @_;
287 return $self->get_write_method_ref()->($object, $value);
291 my($self, $object) = @_;
292 return $self->get_read_method_ref()->($object);
296 my($self, $object) = @_;
297 my $accessor_ref = $self->{_predicate_ref}
298 ||= $self->_get_accessor_method_ref('predicate', '_generate_predicate');
300 return $accessor_ref->($object);
304 my($self, $object) = @_;
305 my $accessor_ref = $self->{_crealer_ref}
306 ||= $self->_get_accessor_method_ref('clearer', '_generate_clearer');
308 return $accessor_ref->($object);
312 sub associate_method{
313 my ($attribute, $method_name) = @_;
314 $attribute->{associated_methods}++;
318 sub install_accessors{
321 my $metaclass = $attribute->associated_class;
322 my $accessor_class = $attribute->accessor_metaclass;
324 foreach my $type(qw(accessor reader writer predicate clearer)){
325 if(exists $attribute->{$type}){
326 my $generator = '_generate_' . $type;
327 my $code = $accessor_class->$generator($attribute, $metaclass);
328 $metaclass->add_method($attribute->{$type} => $code);
329 $attribute->associate_method($attribute->{$type});
334 if(exists $attribute->{handles}){
335 my %handles = $attribute->_canonicalize_handles($attribute->{handles});
337 while(my($handle, $method_to_call) = each %handles){
338 $metaclass->add_method($handle =>
339 $attribute->_make_delegation_method(
340 $handle, $method_to_call));
342 $attribute->associate_method($handle);
349 sub delegation_metaclass() { 'Mouse::Meta::Method::Delegation' }
351 sub _canonicalize_handles {
352 my($self, $handles) = @_;
354 if (ref($handles) eq 'HASH') {
357 elsif (ref($handles) eq 'ARRAY') {
358 return map { $_ => $_ } @$handles;
360 elsif (ref($handles) eq 'Regexp') {
361 my $class_or_role = ($self->{isa} || $self->{does})
362 || $self->throw_error("Cannot delegate methods based on a Regexp without a type constraint (isa)");
364 my $meta = Mouse::Meta::Class->initialize("$class_or_role"); # "" for stringify
365 return map { $_ => $_ }
366 grep { !Mouse::Object->can($_) && $_ =~ $handles }
367 Mouse::Util::is_a_metarole($meta)
368 ? $meta->get_method_list
369 : $meta->get_all_method_names;
372 $self->throw_error("Unable to canonicalize the 'handles' option with $handles");
376 sub _make_delegation_method {
377 my($self, $handle, $method_to_call) = @_;
378 my $delegator = $self->delegation_metaclass;
379 Mouse::Util::load_class($delegator);
381 return $delegator->_generate_delegation($self, $handle, $method_to_call);
387 my $metaclass = (ref $self && $self->associated_class) || 'Mouse::Meta::Class';
388 $metaclass->throw_error(@_, depth => 1);
396 Mouse::Meta::Attribute - The Mouse attribute metaclass
400 This document describes Mouse version 0.45
404 =head2 C<< new(%options) -> Mouse::Meta::Attribute >>
406 Instantiates a new Mouse::Meta::Attribute. Does nothing else.
408 It adds the following options to the constructor:
412 =item C<< is => 'ro', 'rw', 'bare' >>
414 This provides a shorthand for specifying the C<reader>, C<writer>, or
415 C<accessor> names. If the attribute is read-only ('ro') then it will
416 have a C<reader> method with the same attribute as the name.
418 If it is read-write ('rw') then it will have an C<accessor> method
419 with the same name. If you provide an explicit C<writer> for a
420 read-write attribute, then you will have a C<reader> with the same
421 name as the attribute, and a C<writer> with the name you provided.
423 Use 'bare' when you are deliberately not installing any methods
424 (accessor, reader, etc.) associated with this attribute; otherwise,
425 Moose will issue a deprecation warning when this attribute is added to a
428 =item C<< isa => Type >>
430 This option accepts a type. The type can be a string, which should be
431 a type name. If the type name is unknown, it is assumed to be a class
434 This option can also accept a L<Moose::Meta::TypeConstraint> object.
436 If you I<also> provide a C<does> option, then your C<isa> option must
437 be a class name, and that class must do the role specified with
440 =item C<< does => Role >>
442 This is short-hand for saying that the attribute's type must be an
443 object which does the named role.
445 B<This option is not yet supported.>
447 =item C<< coerce => Bool >>
449 This option is only valid for objects with a type constraint
450 (C<isa>). If this is true, then coercions will be applied whenever
451 this attribute is set.
453 You can make both this and the C<weak_ref> option true.
455 =item C<< trigger => CodeRef >>
457 This option accepts a subroutine reference, which will be called after
458 the attribute is set.
460 =item C<< required => Bool >>
462 An attribute which is required must be provided to the constructor. An
463 attribute which is required can also have a C<default> or C<builder>,
464 which will satisfy its required-ness.
466 A required attribute must have a C<default>, C<builder> or a
467 non-C<undef> C<init_arg>
469 =item C<< lazy => Bool >>
471 A lazy attribute must have a C<default> or C<builder>. When an
472 attribute is lazy, the default value will not be calculated until the
475 =item C<< weak_ref => Bool >>
477 If this is true, the attribute's value will be stored as a weak
480 =item C<< auto_deref => Bool >>
482 If this is true, then the reader will dereference the value when it is
483 called. The attribute must have a type constraint which defines the
484 attribute as an array or hash reference.
486 =item C<< lazy_build => Bool >>
488 Setting this to true makes the attribute lazy and provides a number of
496 is equivalent to this:
501 builder => '_build_size',
502 clearer => 'clear_size',
503 predicate => 'has_size',
508 =head2 C<< associate_method(MethodName) >>
510 Associates a method with the attribute. Typically, this is called internally
511 when an attribute generates its accessors.
513 Currently the argument I<MethodName> is ignored in Mouse.
515 =head2 C<< verify_against_type_constraint(Item) -> TRUE | ERROR >>
517 Checks that the given value passes this attribute's type constraint. Returns C<true>
518 on success, otherwise C<confess>es.
520 =head2 C<< clone_and_inherit_options(options) -> Mouse::Meta::Attribute >>
522 Creates a new attribute in the owner class, inheriting options from parent classes.
523 Accessors and helper methods are installed. Some error checking is done.
525 =head2 C<< get_read_method_ref >>
527 =head2 C<< get_write_method_ref >>
529 Returns the subroutine reference of a method suitable for reading or
530 writing the attribute's value in the associated class. These methods
531 always return a subroutine reference, regardless of whether or not the
532 attribute is read- or write-only.
536 L<Moose::Meta::Attribute>
538 L<Class::MOP::Attribute>