2 package Mouse::Meta::Attribute;
7 use Mouse::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} }
39 sub should_coerce { $_[0]->{should_coerce} }
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;
56 my $name = $self->name;
57 my $key = "'" . $name . "'";
61 sub generate_accessor {
62 my $attribute = shift;
64 my $name = $attribute->name;
65 my $default = $attribute->default;
66 my $type = $attribute->type_constraint;
67 my $constraint = $attribute->find_type_constraint;
68 my $builder = $attribute->builder;
69 my $trigger = $attribute->trigger;
70 my $is_weak = $attribute->is_weak_ref;
71 my $should_deref = $attribute->should_auto_deref;
72 my $should_coerce = $attribute->should_coerce;
75 my $key = $attribute->inlined_name;
77 my $accessor = "sub {\n";
78 if ($attribute->_is_metadata eq 'rw') {
79 $accessor .= 'if (scalar(@_) >= 2) {' . "\n";
85 $accessor .= $value.' = $attribute->coerce_constraint('.$value.');';
87 $accessor .= 'local $_ = '.$value.';';
89 unless ($constraint->()) {
90 my $display = defined($_) ? overload::StrVal($_) : "undef";
91 Carp::confess("Attribute ($name) does not pass the type constraint because: Validation failed for \'$type\' failed with value $display");
95 # if there's nothing left to do for the attribute we can return during
97 $accessor .= 'return ' if !$is_weak && !$trigger && !$should_deref;
99 $accessor .= $self.'->{'.$key.'} = '.$value.';' . "\n";
102 $accessor .= 'weaken('.$self.'->{'.$key.'}) if ref('.$self.'->{'.$key.'});' . "\n";
106 $accessor .= '$trigger->('.$self.', '.$value.', $attribute);' . "\n";
112 $accessor .= 'confess "Cannot assign a value to a read-only accessor" if scalar(@_) >= 2;' . "\n";
115 if ($attribute->is_lazy) {
116 $accessor .= $self.'->{'.$key.'} = ';
118 $accessor .= $attribute->has_builder
120 : ref($default) eq 'CODE'
121 ? '$default->('.$self.')'
123 $accessor .= ' if !exists '.$self.'->{'.$key.'};' . "\n";
127 if ($attribute->type_constraint eq 'ArrayRef') {
128 $accessor .= 'if (wantarray) {
129 return @{ '.$self.'->{'.$key.'} || [] };
133 $accessor .= 'if (wantarray) {
134 return %{ '.$self.'->{'.$key.'} || {} };
139 $accessor .= 'return '.$self.'->{'.$key.'};
142 my $sub = eval $accessor;
147 sub generate_predicate {
148 my $attribute = shift;
149 my $key = $attribute->inlined_name;
151 my $predicate = 'sub { exists($_[0]->{'.$key.'}) }';
153 my $sub = eval $predicate;
158 sub generate_clearer {
159 my $attribute = shift;
160 my $key = $attribute->inlined_name;
162 my $clearer = 'sub { delete($_[0]->{'.$key.'}) }';
164 my $sub = eval $clearer;
169 sub generate_handles {
170 my $attribute = shift;
171 my $reader = $attribute->name;
172 my %handles = $attribute->_canonicalize_handles($attribute->handles);
176 for my $local_method (keys %handles) {
177 my $remote_method = $handles{$local_method};
181 $self->$reader->$remote_method(@_)
184 $method_map{$local_method} = eval $method;
192 my ($self, $class, $name, %args) = @_;
195 $args{associated_class} = $class;
197 %args = $self->canonicalize_args($name, %args);
198 $self->validate_args($name, \%args);
200 $args{should_coerce} = delete $args{coerce}
201 if exists $args{coerce};
203 $args{type_constraint} = delete $args{isa}
204 if exists $args{isa};
206 my $attribute = $self->new(%args);
208 $attribute->_create_args(\%args);
210 $class->add_attribute($attribute);
212 # install an accessor
213 if ($attribute->_is_metadata eq 'rw' || $attribute->_is_metadata eq 'ro') {
214 my $accessor = $attribute->generate_accessor;
215 $class->add_method($name => $accessor);
218 for my $method (qw/predicate clearer/) {
219 my $predicate = "has_$method";
220 if ($attribute->$predicate) {
221 my $generator = "generate_$method";
222 my $coderef = $attribute->$generator;
223 $class->add_method($attribute->$method => $coderef);
227 if ($attribute->has_handles) {
228 my $method_map = $attribute->generate_handles;
229 for my $method_name (keys %$method_map) {
230 $class->add_method($method_name => $method_map->{$method_name});
237 sub canonicalize_args {
242 if ($args{lazy_build}) {
245 $args{builder} = "_build_${name}"
246 if !exists($args{builder});
248 $args{clearer} = "_clear${name}" if !exists($args{clearer});
249 $args{predicate} = "_has${name}" if !exists($args{predicate});
252 $args{clearer} = "clear_${name}" if !exists($args{clearer});
253 $args{predicate} = "has_${name}" if !exists($args{predicate});
265 confess "You can not use lazy_build and default for the same attribute ($name)"
266 if $args->{lazy_build} && exists $args->{default};
268 confess "You cannot have lazy attribute ($name) without specifying a default value for it"
270 && !exists($args->{default})
271 && !exists($args->{builder});
273 confess "References are not allowed as default values, you must wrap the default of '$name' in a CODE reference (ex: sub { [] } and not [])"
274 if ref($args->{default})
275 && ref($args->{default}) ne 'CODE';
277 confess "You cannot auto-dereference without specifying a type constraint on attribute ($name)"
278 if $args->{auto_deref} && !exists($args->{isa});
280 confess "You cannot auto-dereference anything other than a ArrayRef or HashRef on attribute ($name)"
281 if $args->{auto_deref}
282 && $args->{isa} ne 'ArrayRef'
283 && $args->{isa} ne 'HashRef';
285 if ($args->{trigger}) {
286 if (ref($args->{trigger}) eq 'HASH') {
287 Carp::carp "HASH-based form of trigger has been removed. Only the coderef form of triggers are now supported.";
290 confess "Trigger must be a CODE ref on attribute ($name)"
291 if ref($args->{trigger}) ne 'CODE';
297 sub find_type_constraint {
299 my $type = $self->type_constraint;
303 my $checker = Mouse::TypeRegistry->optimized_constraints($self->associated_class->name)->{$type};
304 return $checker if $checker;
306 return sub { blessed($_) && blessed($_) eq $type };
309 sub verify_type_constraint {
313 my $type = $self->type_constraint
315 my $constraint = $self->find_type_constraint;
317 return 1 if $constraint->($_);
319 my $name = $self->name;
320 my $display = defined($_) ? overload::StrVal($_) : 'undef';
321 Carp::confess("Attribute ($name) does not pass the type constraint because: Validation failed for \'$type\' failed with value $display");
324 sub coerce_constraint {
325 my($self, $value) = @_;
326 my $type = $self->type_constraint
328 return Mouse::TypeRegistry->typecast_constraints($self->associated_class->name, $type, $value);
331 sub _canonicalize_handles {
335 if (ref($handles) eq 'HASH') {
338 elsif (ref($handles) eq 'ARRAY') {
339 return map { $_ => $_ } @$handles;
342 confess "Unable to canonicalize the 'handles' option with $handles";
350 my %args = ($self->get_parent_args($class, $name), @_);
352 $self->create($class, $name, %args);
355 sub get_parent_args {
360 for my $super ($class->linearized_isa) {
361 my $super_attr = $super->can("meta") && $super->meta->get_attribute($name)
363 return %{ $super_attr->_create_args };
366 confess "Could not find an attribute by the name of '$name' to inherit from";
375 Mouse::Meta::Attribute - attribute metaclass
379 =head2 new %args -> Mouse::Meta::Attribute
381 Instantiates a new Mouse::Meta::Attribute. Does nothing else.
383 =head2 create OwnerClass, AttributeName, %args -> Mouse::Meta::Attribute
385 Creates a new attribute in OwnerClass. Accessors and helper methods are
386 installed. Some error checking is done.
388 =head2 name -> AttributeName
390 =head2 associated_class -> OwnerClass
392 =head2 is_required -> Bool
394 =head2 default -> Item
396 =head2 has_default -> Bool
398 =head2 is_lazy -> Bool
400 =head2 predicate -> MethodName | Undef
402 =head2 has_predicate -> Bool
404 =head2 clearer -> MethodName | Undef
406 =head2 has_clearer -> Bool
408 =head2 handles -> { LocalName => RemoteName }
410 =head2 has_handles -> Bool
412 =head2 is_weak_ref -> Bool
414 =head2 init_arg -> Str
416 =head2 type_constraint -> Str
418 =head2 has_type_constraint -> Bool
420 =head2 trigger => CODE | Undef
422 =head2 has_trigger -> Bool
424 =head2 builder => MethodName | Undef
426 =head2 has_builder -> Bool
428 =head2 is_lazy_build => Bool
430 =head2 should_auto_deref -> Bool
432 Informational methods.
434 =head2 generate_accessor -> CODE
436 Creates a new code reference for the attribute's accessor.
438 =head2 generate_predicate -> CODE
440 Creates a new code reference for the attribute's predicate.
442 =head2 generate_clearer -> CODE
444 Creates a new code reference for the attribute's clearer.
446 =head2 generate_handles -> { MethodName => CODE }
448 Creates a new code reference for each of the attribute's handles methods.
450 =head2 find_type_constraint -> CODE
452 Returns a code reference which can be used to check that a given value passes
453 this attribute's type constraint;
455 =head2 verify_type_constraint Item -> 1 | ERROR
457 Checks that the given value passes this attribute's type constraint. Returns 1
458 on success, otherwise C<confess>es.
460 =head2 canonicalize_args Name, %args -> %args
462 Canonicalizes some arguments to create. In particular, C<lazy_build> is
463 canonicalized into C<lazy>, C<builder>, etc.
465 =head2 validate_args Name, \%args -> 1 | ERROR
467 Checks that the arguments to create the attribute (ie those specified by
470 =head2 clone_parent OwnerClass, AttributeName, %args -> Mouse::Meta::Attribute
472 Creates a new attribute in OwnerClass, inheriting options from parent classes.
473 Accessors and helper methods are installed. Some error checking is done.
475 =head2 get_parent_args OwnerClass, AttributeName -> Hash
477 Returns the options that the parent class of C<OwnerClass> used for attribute