2 package Mouse::Meta::Attribute;
7 use Scalar::Util 'blessed';
13 my $name = $args{name};
15 $args{init_arg} = $name
16 unless exists $args{init_arg};
23 sub name { $_[0]->{name} }
24 sub class { $_[0]->{class} }
25 sub _is_metadata { $_[0]->{is} }
26 sub is_required { $_[0]->{required} }
27 sub default { $_[0]->{default} }
28 sub is_lazy { $_[0]->{lazy} }
29 sub is_lazy_build { $_[0]->{lazy_build} }
30 sub predicate { $_[0]->{predicate} }
31 sub clearer { $_[0]->{clearer} }
32 sub handles { $_[0]->{handles} }
33 sub is_weak_ref { $_[0]->{weak_ref} }
34 sub init_arg { $_[0]->{init_arg} }
35 sub type_constraint { $_[0]->{type_constraint} }
36 sub trigger { $_[0]->{trigger} }
37 sub builder { $_[0]->{builder} }
38 sub should_auto_deref { $_[0]->{auto_deref} }
40 sub has_default { exists $_[0]->{default} }
41 sub has_predicate { exists $_[0]->{predicate} }
42 sub has_clearer { exists $_[0]->{clearer} }
43 sub has_handles { exists $_[0]->{handles} }
44 sub has_type_constraint { exists $_[0]->{type_constraint} }
45 sub has_trigger { exists $_[0]->{trigger} }
46 sub has_builder { exists $_[0]->{builder} }
49 $_[0]->{_create_args} = $_[1] if @_ > 1;
53 sub generate_accessor {
54 my $attribute = shift;
56 my $name = $attribute->name;
58 my $default = $attribute->default;
59 my $trigger = $attribute->trigger;
60 my $type = $attribute->type_constraint;
61 my $constraint = $attribute->find_type_constraint;
62 my $builder = $attribute->builder;
67 if ($attribute->_is_metadata eq 'rw') {
68 $accessor .= 'if (@_) {
73 my $display = defined($_) ? overload::StrVal($_) : "undef";
74 Carp::confess("Attribute ($name) does not pass the type constraint because: Validation failed for \'$type\' failed with value $display") unless $constraint->();
78 $accessor .= '$self->{$key} = $_;';
80 if ($attribute->is_weak_ref) {
81 $accessor .= 'Scalar::Util::weaken($self->{$key}) if ref($self->{$key});';
85 $accessor .= '$trigger->($self, $_, $attribute);';
91 $accessor .= 'confess "Cannot assign a value to a read-only accessor" if @_;';
94 if ($attribute->is_lazy) {
95 $accessor .= '$self->{$key} = ';
97 $accessor .= $attribute->has_builder
99 : ref($default) eq 'CODE'
100 ? '$default->($self)'
103 $accessor .= ' if !exists($self->{$key});';
106 if ($attribute->should_auto_deref) {
107 if ($attribute->type_constraint eq 'ArrayRef') {
108 $accessor .= 'if (wantarray) {
109 return @{ $self->{$key} || [] };
113 $accessor .= 'if (wantarray) {
114 return %{ $self->{$key} || {} };
119 $accessor .= 'return $self->{$key};
122 return eval $accessor;
125 sub generate_predicate {
126 my $attribute = shift;
127 my $key = $attribute->name;
129 my $predicate = 'sub { exists($_[0]->{$key}) }';
131 return eval $predicate;
134 sub generate_clearer {
135 my $attribute = shift;
136 my $key = $attribute->name;
138 my $predicate = 'sub { delete($_[0]->{$key}) }';
140 return eval $predicate;
143 sub generate_handles {
144 my $attribute = shift;
145 my $reader = $attribute->name;
146 my %handles = $attribute->_canonicalize_handles($attribute->handles);
150 for my $local_method (keys %handles) {
151 my $remote_method = $handles{$local_method};
155 $self->$reader->$remote_method(@_)
158 $method_map{$local_method} = eval $method;
165 my ($self, $class, $name, %args) = @_;
168 $args{class} = $class;
170 %args = $self->canonicalize_args($name, %args);
171 $self->validate_args($name, \%args);
173 $args{type_constraint} = delete $args{isa}
174 if exists $args{isa};
176 my $attribute = $self->new(%args);
177 $attribute->_create_args(\%args);
179 my $meta = $class->meta;
181 $meta->add_attribute($attribute);
183 # install an accessor
184 if ($attribute->_is_metadata eq 'rw' || $attribute->_is_metadata eq 'ro') {
185 my $accessor = $attribute->generate_accessor;
187 *{ $class . '::' . $name } = $accessor;
190 for my $method (qw/predicate clearer/) {
191 my $predicate = "has_$method";
192 if ($attribute->$predicate) {
193 my $generator = "generate_$method";
194 my $coderef = $attribute->$generator;
196 *{ $class . '::' . $attribute->$method } = $coderef;
200 if ($attribute->has_handles) {
201 my $method_map = $attribute->generate_handles;
202 for my $method_name (keys %$method_map) {
204 *{ $class . '::' . $method_name } = $method_map->{$method_name};
211 sub canonicalize_args {
216 if ($args{lazy_build}) {
219 $args{builder} = "_build_${name}"
220 if !exists($args{builder});
222 $args{clearer} = "_clear${name}" if !exists($args{clearer});
223 $args{predicate} = "_has${name}" if !exists($args{predicate});
226 $args{clearer} = "clear_${name}" if !exists($args{clearer});
227 $args{predicate} = "has_${name}" if !exists($args{predicate});
239 confess "You can not use lazy_build and default for the same attribute ($name)"
240 if $args->{lazy_build} && exists $args->{default};
242 confess "You cannot have lazy attribute ($name) without specifying a default value for it"
244 && !exists($args->{default})
245 && !exists($args->{builder});
247 confess "References are not allowed as default values, you must wrap the default of '$name' in a CODE reference (ex: sub { [] } and not [])"
248 if ref($args->{default})
249 && ref($args->{default}) ne 'CODE';
251 confess "You cannot auto-dereference without specifying a type constraint on attribute $name"
252 if $args->{auto_deref} && !exists($args->{isa});
254 confess "You cannot auto-dereference anything other than a ArrayRef or HashRef on attribute $name"
255 if $args->{auto_deref}
256 && $args->{isa} ne 'ArrayRef'
257 && $args->{isa} ne 'HashRef';
259 confess "Trigger must be a CODE or HASH ref on attribute ($name)"
261 && ref($args{trigger}) ne 'CODE' && ref($args{trigger}) ne 'HASH';
266 sub find_type_constraint {
268 my $type = $self->type_constraint;
272 my $checker = Mouse::TypeRegistry->optimized_constraints->{$type};
273 return $checker if $checker;
275 return sub { blessed($_) && blessed($_) eq $type };
278 sub verify_type_constraint {
282 my $type = $self->type_constraint
284 my $constraint = $self->find_type_constraint;
286 return 1 if $constraint->($_);
288 my $name = $self->name;
289 my $display = defined($_) ? overload::StrVal($_) : 'undef';
290 Carp::confess("Attribute ($name) does not pass the type constraint because: Validation failed for \'$type\' failed with value $display");
293 sub _canonicalize_handles {
297 if (ref($handles) eq 'HASH') {
300 elsif (ref($handles) eq 'ARRAY') {
301 return map { $_ => $_ } @$handles;
304 confess "Unable to canonicalize the 'handles' option with $handles";
312 my %args = ($self->get_parent_args($class, $name), @_);
314 $self->create($class, $name, %args);
317 sub get_parent_args {
322 for my $super ($class->meta->linearized_isa) {
323 my $super_attr = $super->can("meta") && $super->meta->get_attribute($name)
325 return %{ $super_attr->_create_args };
328 confess "Could not find an attribute by the name of '$name' to inherit from";
337 Mouse::Meta::Attribute - attribute metaclass
341 =head2 new %args -> Mouse::Meta::Attribute
343 Instantiates a new Mouse::Meta::Attribute. Does nothing else.
345 =head2 create OwnerClass, AttributeName, %args -> Mouse::Meta::Attribute
347 Creates a new attribute in OwnerClass. Accessors and helper methods are
348 installed. Some error checking is done.
350 =head2 name -> AttributeName
352 =head2 class -> OwnerClass
354 =head2 is_required -> Bool
356 =head2 default -> Item
358 =head2 has_default -> Bool
360 =head2 is_lazy -> Bool
362 =head2 predicate -> MethodName | Undef
364 =head2 has_predicate -> Bool
366 =head2 clearer -> MethodName | Undef
368 =head2 has_clearer -> Bool
370 =head2 handles -> { LocalName => RemoteName }
372 =head2 has_handles -> Bool
374 =head2 is_weak_ref -> Bool
376 =head2 init_arg -> Str
378 =head2 type_constraint -> Str
380 =head2 has_type_constraint -> Bool
382 =head2 trigger => CODE | Undef
384 =head2 has_trigger -> Bool
386 =head2 builder => MethodName | Undef
388 =head2 has_builder -> Bool
390 =head2 is_lazy_build => Bool
392 =head2 should_auto_deref -> Bool
394 Informational methods.
396 =head2 generate_accessor -> CODE
398 Creates a new code reference for the attribute's accessor.
400 =head2 generate_predicate -> CODE
402 Creates a new code reference for the attribute's predicate.
404 =head2 generate_clearer -> CODE
406 Creates a new code reference for the attribute's clearer.
408 =head2 generate_handles -> { MethodName => CODE }
410 Creates a new code reference for each of the attribute's handles methods.
412 =head2 find_type_constraint -> CODE
414 Returns a code reference which can be used to check that a given value passes
415 this attribute's type constraint;
417 =head2 verify_type_constraint Item -> 1 | ERROR
419 Checks that the given value passes this attribute's type constraint. Returns 1
420 on success, otherwise C<confess>es.
422 =head2 canonicalize_args Name, %args -> %args
424 Canonicalizes some arguments to create. In particular, C<lazy_build> is
425 canonicalized into C<lazy>, C<builder>, etc.
427 =head2 validate_args Name, \%args -> 1 | ERROR
429 Checks that the arguments to create the attribute (ie those specified by
432 =head2 clone_parent OwnerClass, AttributeName, %args -> Mouse::Meta::Attribute
434 Creates a new attribute in OwnerClass, inheriting options from parent classes.
435 Accessors and helper methods are installed. Some error checking is done.
437 =head2 get_parent_args OwnerClass, AttributeName -> Hash
439 Returns the options that the parent class of C<OwnerClass> used for attribute