2 package Mouse::Meta::Attribute;
7 use Mouse::Util 'blessed';
8 use Scalar::Util 'weaken';
14 my $name = $args{name};
16 $args{init_arg} = $name
17 unless exists $args{init_arg};
24 sub name { $_[0]->{name} }
25 sub associated_class { $_[0]->{associated_class} }
26 sub _is_metadata { $_[0]->{is} }
27 sub is_required { $_[0]->{required} }
28 sub default { $_[0]->{default} }
29 sub is_lazy { $_[0]->{lazy} }
30 sub is_lazy_build { $_[0]->{lazy_build} }
31 sub predicate { $_[0]->{predicate} }
32 sub clearer { $_[0]->{clearer} }
33 sub handles { $_[0]->{handles} }
34 sub is_weak_ref { $_[0]->{weak_ref} }
35 sub init_arg { $_[0]->{init_arg} }
36 sub type_constraint { $_[0]->{type_constraint} }
37 sub trigger { $_[0]->{trigger} }
38 sub builder { $_[0]->{builder} }
39 sub should_auto_deref { $_[0]->{auto_deref} }
41 sub has_default { exists $_[0]->{default} }
42 sub has_predicate { exists $_[0]->{predicate} }
43 sub has_clearer { exists $_[0]->{clearer} }
44 sub has_handles { exists $_[0]->{handles} }
45 sub has_type_constraint { exists $_[0]->{type_constraint} }
46 sub has_trigger { exists $_[0]->{trigger} }
47 sub has_builder { exists $_[0]->{builder} }
50 $_[0]->{_create_args} = $_[1] if @_ > 1;
54 sub generate_accessor {
55 my $attribute = shift;
57 my $name = $attribute->name;
59 my $default = $attribute->default;
60 my $type = $attribute->type_constraint;
61 my $constraint = $attribute->find_type_constraint;
62 my $builder = $attribute->builder;
63 my $trigger = $attribute->trigger;
68 if ($attribute->_is_metadata eq 'rw') {
69 $accessor .= 'if (@_) {
73 $accessor .= 'unless ($constraint->()) {
74 my $display = defined($_) ? overload::StrVal($_) : "undef";
75 Carp::confess("Attribute ($name) does not pass the type constraint because: Validation failed for \'$type\' failed with value $display");
79 $accessor .= '$self->{$key} = $_;';
81 if ($attribute->is_weak_ref) {
82 $accessor .= 'Scalar::Util::weaken($self->{$key}) if ref($self->{$key});';
86 $accessor .= '$trigger->($self, $_, $attribute);';
92 $accessor .= 'confess "Cannot assign a value to a read-only accessor" if @_;';
95 if ($attribute->is_lazy) {
96 $accessor .= '$self->{$key} = ';
98 $accessor .= $attribute->has_builder
100 : ref($default) eq 'CODE'
101 ? '$default->($self)'
104 $accessor .= ' if !exists($self->{$key});';
107 if ($attribute->should_auto_deref) {
108 if ($attribute->type_constraint eq 'ArrayRef') {
109 $accessor .= 'if (wantarray) {
110 return @{ $self->{$key} || [] };
114 $accessor .= 'if (wantarray) {
115 return %{ $self->{$key} || {} };
120 $accessor .= 'return $self->{$key};
123 return eval $accessor;
126 sub generate_predicate {
127 my $attribute = shift;
128 my $key = $attribute->name;
130 my $predicate = 'sub { exists($_[0]->{$key}) }';
132 return eval $predicate;
135 sub generate_clearer {
136 my $attribute = shift;
137 my $key = $attribute->name;
139 my $predicate = 'sub { delete($_[0]->{$key}) }';
141 return eval $predicate;
144 sub generate_handles {
145 my $attribute = shift;
146 my $reader = $attribute->name;
147 my %handles = $attribute->_canonicalize_handles($attribute->handles);
151 for my $local_method (keys %handles) {
152 my $remote_method = $handles{$local_method};
156 $self->$reader->$remote_method(@_)
159 $method_map{$local_method} = eval $method;
166 my ($self, $class, $name, %args) = @_;
169 $args{associated_class} = $class;
171 %args = $self->canonicalize_args($name, %args);
172 $self->validate_args($name, \%args);
174 $args{type_constraint} = delete $args{isa}
175 if exists $args{isa};
177 my $attribute = $self->new(%args);
179 $attribute->_create_args(\%args);
181 $class->add_attribute($attribute);
183 # install an accessor
184 if ($attribute->_is_metadata eq 'rw' || $attribute->_is_metadata eq 'ro') {
185 my $accessor = $attribute->generate_accessor;
186 $class->add_method($name => $accessor);
189 for my $method (qw/predicate clearer/) {
190 my $predicate = "has_$method";
191 if ($attribute->$predicate) {
192 my $generator = "generate_$method";
193 my $coderef = $attribute->$generator;
194 $class->add_method($attribute->$method => $coderef);
198 if ($attribute->has_handles) {
199 my $method_map = $attribute->generate_handles;
200 for my $method_name (keys %$method_map) {
201 $class->add_method($method_name => $method_map->{$method_name});
208 sub canonicalize_args {
213 if ($args{lazy_build}) {
216 $args{builder} = "_build_${name}"
217 if !exists($args{builder});
219 $args{clearer} = "_clear${name}" if !exists($args{clearer});
220 $args{predicate} = "_has${name}" if !exists($args{predicate});
223 $args{clearer} = "clear_${name}" if !exists($args{clearer});
224 $args{predicate} = "has_${name}" if !exists($args{predicate});
236 confess "You can not use lazy_build and default for the same attribute ($name)"
237 if $args->{lazy_build} && exists $args->{default};
239 confess "You cannot have lazy attribute ($name) without specifying a default value for it"
241 && !exists($args->{default})
242 && !exists($args->{builder});
244 confess "References are not allowed as default values, you must wrap the default of '$name' in a CODE reference (ex: sub { [] } and not [])"
245 if ref($args->{default})
246 && ref($args->{default}) ne 'CODE';
248 confess "You cannot auto-dereference without specifying a type constraint on attribute ($name)"
249 if $args->{auto_deref} && !exists($args->{isa});
251 confess "You cannot auto-dereference anything other than a ArrayRef or HashRef on attribute ($name)"
252 if $args->{auto_deref}
253 && $args->{isa} ne 'ArrayRef'
254 && $args->{isa} ne 'HashRef';
256 if ($args->{trigger}) {
257 if (ref($args->{trigger}) eq 'HASH') {
258 Carp::carp "HASH-based form of trigger has been removed. Only the coderef form of triggers are now supported.";
261 confess "Trigger must be a CODE ref on attribute ($name)"
262 if ref($args->{trigger}) ne 'CODE';
268 sub find_type_constraint {
270 my $type = $self->type_constraint;
274 my $checker = Mouse::TypeRegistry->optimized_constraints->{$type};
275 return $checker if $checker;
277 return sub { blessed($_) && blessed($_) eq $type };
280 sub verify_type_constraint {
284 my $type = $self->type_constraint
286 my $constraint = $self->find_type_constraint;
288 return 1 if $constraint->($_);
290 my $name = $self->name;
291 my $display = defined($_) ? overload::StrVal($_) : 'undef';
292 Carp::confess("Attribute ($name) does not pass the type constraint because: Validation failed for \'$type\' failed with value $display");
295 sub _canonicalize_handles {
299 if (ref($handles) eq 'HASH') {
302 elsif (ref($handles) eq 'ARRAY') {
303 return map { $_ => $_ } @$handles;
306 confess "Unable to canonicalize the 'handles' option with $handles";
314 my %args = ($self->get_parent_args($class, $name), @_);
316 $self->create($class, $name, %args);
319 sub get_parent_args {
324 for my $super ($class->linearized_isa) {
325 my $super_attr = $super->can("meta") && $super->meta->get_attribute($name)
327 return %{ $super_attr->_create_args };
330 confess "Could not find an attribute by the name of '$name' to inherit from";
339 Mouse::Meta::Attribute - attribute metaclass
343 =head2 new %args -> Mouse::Meta::Attribute
345 Instantiates a new Mouse::Meta::Attribute. Does nothing else.
347 =head2 create OwnerClass, AttributeName, %args -> Mouse::Meta::Attribute
349 Creates a new attribute in OwnerClass. Accessors and helper methods are
350 installed. Some error checking is done.
352 =head2 name -> AttributeName
354 =head2 associated_class -> OwnerClass
356 =head2 is_required -> Bool
358 =head2 default -> Item
360 =head2 has_default -> Bool
362 =head2 is_lazy -> Bool
364 =head2 predicate -> MethodName | Undef
366 =head2 has_predicate -> Bool
368 =head2 clearer -> MethodName | Undef
370 =head2 has_clearer -> Bool
372 =head2 handles -> { LocalName => RemoteName }
374 =head2 has_handles -> Bool
376 =head2 is_weak_ref -> Bool
378 =head2 init_arg -> Str
380 =head2 type_constraint -> Str
382 =head2 has_type_constraint -> Bool
384 =head2 trigger => CODE | Undef
386 =head2 has_trigger -> Bool
388 =head2 builder => MethodName | Undef
390 =head2 has_builder -> Bool
392 =head2 is_lazy_build => Bool
394 =head2 should_auto_deref -> Bool
396 Informational methods.
398 =head2 generate_accessor -> CODE
400 Creates a new code reference for the attribute's accessor.
402 =head2 generate_predicate -> CODE
404 Creates a new code reference for the attribute's predicate.
406 =head2 generate_clearer -> CODE
408 Creates a new code reference for the attribute's clearer.
410 =head2 generate_handles -> { MethodName => CODE }
412 Creates a new code reference for each of the attribute's handles methods.
414 =head2 find_type_constraint -> CODE
416 Returns a code reference which can be used to check that a given value passes
417 this attribute's type constraint;
419 =head2 verify_type_constraint Item -> 1 | ERROR
421 Checks that the given value passes this attribute's type constraint. Returns 1
422 on success, otherwise C<confess>es.
424 =head2 canonicalize_args Name, %args -> %args
426 Canonicalizes some arguments to create. In particular, C<lazy_build> is
427 canonicalized into C<lazy>, C<builder>, etc.
429 =head2 validate_args Name, \%args -> 1 | ERROR
431 Checks that the arguments to create the attribute (ie those specified by
434 =head2 clone_parent OwnerClass, AttributeName, %args -> Mouse::Meta::Attribute
436 Creates a new attribute in OwnerClass, inheriting options from parent classes.
437 Accessors and helper methods are installed. Some error checking is done.
439 =head2 get_parent_args OwnerClass, AttributeName -> Hash
441 Returns the options that the parent class of C<OwnerClass> used for attribute