2 package Mouse::Meta::Attribute;
7 use Scalar::Util qw/blessed weaken/;
13 my $name = $args{name};
15 $args{init_arg} = $name
16 unless exists $args{init_arg};
23 sub name { $_[0]->{name} }
24 sub associated_class { $_[0]->{associated_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 $type = $attribute->type_constraint;
60 my $constraint = $attribute->find_type_constraint;
61 my $builder = $attribute->builder;
63 my $trigger = $attribute->trigger;
64 my $before = $trigger->{before};
65 my $after = $trigger->{after};
66 my $around = $trigger->{around};
71 if ($attribute->_is_metadata eq 'rw') {
72 $accessor .= 'if (@_) {
76 $accessor .= '$before->($self, $_, $attribute);';
80 $accessor .= '$around->(sub {
87 $accessor .= 'unless ($constraint->()) {
88 my $display = defined($_) ? overload::StrVal($_) : "undef";
89 Carp::confess("Attribute ($name) does not pass the type constraint because: Validation failed for \'$type\' failed with value $display");
93 $accessor .= '$self->{$key} = $_;';
95 if ($attribute->is_weak_ref) {
96 $accessor .= 'Scalar::Util::weaken($self->{$key}) if ref($self->{$key});';
100 $accessor .= '}, $self, $_, $attribute);';
104 $accessor .= '$after->($self, $_, $attribute);';
110 $accessor .= 'confess "Cannot assign a value to a read-only accessor" if @_;';
113 if ($attribute->is_lazy) {
114 $accessor .= '$self->{$key} = ';
116 $accessor .= $attribute->has_builder
118 : ref($default) eq 'CODE'
119 ? '$default->($self)'
122 $accessor .= ' if !exists($self->{$key});';
125 if ($attribute->should_auto_deref) {
126 if ($attribute->type_constraint eq 'ArrayRef') {
127 $accessor .= 'if (wantarray) {
128 return @{ $self->{$key} || [] };
132 $accessor .= 'if (wantarray) {
133 return %{ $self->{$key} || {} };
138 $accessor .= 'return $self->{$key};
141 return eval $accessor;
144 sub generate_predicate {
145 my $attribute = shift;
146 my $key = $attribute->name;
148 my $predicate = 'sub { exists($_[0]->{$key}) }';
150 return eval $predicate;
153 sub generate_clearer {
154 my $attribute = shift;
155 my $key = $attribute->name;
157 my $predicate = 'sub { delete($_[0]->{$key}) }';
159 return eval $predicate;
162 sub generate_handles {
163 my $attribute = shift;
164 my $reader = $attribute->name;
165 my %handles = $attribute->_canonicalize_handles($attribute->handles);
169 for my $local_method (keys %handles) {
170 my $remote_method = $handles{$local_method};
174 $self->$reader->$remote_method(@_)
177 $method_map{$local_method} = eval $method;
184 my ($self, $class, $name, %args) = @_;
187 $args{associated_class} = $class;
189 %args = $self->canonicalize_args($name, %args);
190 $self->validate_args($name, \%args);
192 $args{type_constraint} = delete $args{isa}
193 if exists $args{isa};
195 my $attribute = $self->new(%args);
197 $attribute->_create_args(\%args);
199 $class->add_attribute($attribute);
201 # install an accessor
202 if ($attribute->_is_metadata eq 'rw' || $attribute->_is_metadata eq 'ro') {
203 my $accessor = $attribute->generate_accessor;
204 $class->add_method($name => $accessor);
207 for my $method (qw/predicate clearer/) {
208 my $predicate = "has_$method";
209 if ($attribute->$predicate) {
210 my $generator = "generate_$method";
211 my $coderef = $attribute->$generator;
212 $class->add_method($attribute->$method => $coderef);
216 if ($attribute->has_handles) {
217 my $method_map = $attribute->generate_handles;
218 for my $method_name (keys %$method_map) {
219 $class->add_method($method_name => $method_map->{$method_name});
226 sub canonicalize_args {
231 if ($args{lazy_build}) {
234 $args{builder} = "_build_${name}"
235 if !exists($args{builder});
237 $args{clearer} = "_clear${name}" if !exists($args{clearer});
238 $args{predicate} = "_has${name}" if !exists($args{predicate});
241 $args{clearer} = "clear_${name}" if !exists($args{clearer});
242 $args{predicate} = "has_${name}" if !exists($args{predicate});
254 confess "You can not use lazy_build and default for the same attribute ($name)"
255 if $args->{lazy_build} && exists $args->{default};
257 confess "You cannot have lazy attribute ($name) without specifying a default value for it"
259 && !exists($args->{default})
260 && !exists($args->{builder});
262 confess "References are not allowed as default values, you must wrap the default of '$name' in a CODE reference (ex: sub { [] } and not [])"
263 if ref($args->{default})
264 && ref($args->{default}) ne 'CODE';
266 confess "You cannot auto-dereference without specifying a type constraint on attribute ($name)"
267 if $args->{auto_deref} && !exists($args->{isa});
269 confess "You cannot auto-dereference anything other than a ArrayRef or HashRef on attribute ($name)"
270 if $args->{auto_deref}
271 && $args->{isa} ne 'ArrayRef'
272 && $args->{isa} ne 'HashRef';
274 if ($args->{trigger}) {
275 if (ref($args->{trigger}) eq 'CODE') {
277 after => $args->{trigger},
280 elsif (ref($args->{trigger}) eq 'HASH') {
281 Carp::carp "HASH-based form of trigger is deprecated. Please switch back to using the coderef form of trigger.";
284 confess "Trigger must be a CODE ref on attribute ($name)"
285 if ref($args->{trigger}) ne 'HASH';
291 sub find_type_constraint {
293 my $type = $self->type_constraint;
297 my $checker = Mouse::TypeRegistry->optimized_constraints->{$type};
298 return $checker if $checker;
300 return sub { blessed($_) && blessed($_) eq $type };
303 sub verify_type_constraint {
307 my $type = $self->type_constraint
309 my $constraint = $self->find_type_constraint;
311 return 1 if $constraint->($_);
313 my $name = $self->name;
314 my $display = defined($_) ? overload::StrVal($_) : 'undef';
315 Carp::confess("Attribute ($name) does not pass the type constraint because: Validation failed for \'$type\' failed with value $display");
318 sub _canonicalize_handles {
322 if (ref($handles) eq 'HASH') {
325 elsif (ref($handles) eq 'ARRAY') {
326 return map { $_ => $_ } @$handles;
329 confess "Unable to canonicalize the 'handles' option with $handles";
337 my %args = ($self->get_parent_args($class, $name), @_);
339 $self->create($class, $name, %args);
342 sub get_parent_args {
347 for my $super ($class->linearized_isa) {
348 my $super_attr = $super->can("meta") && $super->meta->get_attribute($name)
350 return %{ $super_attr->_create_args };
353 confess "Could not find an attribute by the name of '$name' to inherit from";
362 Mouse::Meta::Attribute - attribute metaclass
366 =head2 new %args -> Mouse::Meta::Attribute
368 Instantiates a new Mouse::Meta::Attribute. Does nothing else.
370 =head2 create OwnerClass, AttributeName, %args -> Mouse::Meta::Attribute
372 Creates a new attribute in OwnerClass. Accessors and helper methods are
373 installed. Some error checking is done.
375 =head2 name -> AttributeName
377 =head2 associated_class -> OwnerClass
379 =head2 is_required -> Bool
381 =head2 default -> Item
383 =head2 has_default -> Bool
385 =head2 is_lazy -> Bool
387 =head2 predicate -> MethodName | Undef
389 =head2 has_predicate -> Bool
391 =head2 clearer -> MethodName | Undef
393 =head2 has_clearer -> Bool
395 =head2 handles -> { LocalName => RemoteName }
397 =head2 has_handles -> Bool
399 =head2 is_weak_ref -> Bool
401 =head2 init_arg -> Str
403 =head2 type_constraint -> Str
405 =head2 has_type_constraint -> Bool
407 =head2 trigger => CODE | Undef
409 =head2 has_trigger -> Bool
411 =head2 builder => MethodName | Undef
413 =head2 has_builder -> Bool
415 =head2 is_lazy_build => Bool
417 =head2 should_auto_deref -> Bool
419 Informational methods.
421 =head2 generate_accessor -> CODE
423 Creates a new code reference for the attribute's accessor.
425 =head2 generate_predicate -> CODE
427 Creates a new code reference for the attribute's predicate.
429 =head2 generate_clearer -> CODE
431 Creates a new code reference for the attribute's clearer.
433 =head2 generate_handles -> { MethodName => CODE }
435 Creates a new code reference for each of the attribute's handles methods.
437 =head2 find_type_constraint -> CODE
439 Returns a code reference which can be used to check that a given value passes
440 this attribute's type constraint;
442 =head2 verify_type_constraint Item -> 1 | ERROR
444 Checks that the given value passes this attribute's type constraint. Returns 1
445 on success, otherwise C<confess>es.
447 =head2 canonicalize_args Name, %args -> %args
449 Canonicalizes some arguments to create. In particular, C<lazy_build> is
450 canonicalized into C<lazy>, C<builder>, etc.
452 =head2 validate_args Name, \%args -> 1 | ERROR
454 Checks that the arguments to create the attribute (ie those specified by
457 =head2 clone_parent OwnerClass, AttributeName, %args -> Mouse::Meta::Attribute
459 Creates a new attribute in OwnerClass, inheriting options from parent classes.
460 Accessors and helper methods are installed. Some error checking is done.
462 =head2 get_parent_args OwnerClass, AttributeName -> Hash
464 Returns the options that the parent class of C<OwnerClass> used for attribute