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} }
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;
55 my $name = $self->name;
56 my $key = "'" . $name . "'";
60 sub generate_accessor {
61 my $attribute = shift;
63 my $name = $attribute->name;
64 my $default = $attribute->default;
65 my $type = $attribute->type_constraint;
66 my $constraint = $attribute->find_type_constraint;
67 my $builder = $attribute->builder;
68 my $trigger = $attribute->trigger;
71 my $key = $attribute->inlined_name;
73 my $accessor = "sub {\n";
74 if ($attribute->_is_metadata eq 'rw') {
75 $accessor .= 'if (scalar(@_) >= 2) {' . "\n";
80 $accessor .= 'local $_ = '.$value.';
81 unless ($constraint->()) {
82 my $display = defined($_) ? overload::StrVal($_) : "undef";
83 Carp::confess("Attribute ($name) does not pass the type constraint because: Validation failed for \'$type\' failed with value $display");
87 $accessor .= 'return '
88 if !$attribute->is_weak_ref
90 && !$attribute->should_auto_deref;
92 $accessor .= $self.'->{'.$key.'} = '.$value.';' . "\n";
94 if ($attribute->is_weak_ref) {
95 $accessor .= 'weaken('.$self.'->{'.$key.'}) if ref('.$self.'->{'.$key.'});' . "\n";
99 $accessor .= '$trigger->('.$self.', '.$value.', $attribute);' . "\n";
105 $accessor .= 'confess "Cannot assign a value to a read-only accessor" if scalar(@_) >= 2;' . "\n";
108 if ($attribute->is_lazy) {
109 $accessor .= $self.'->{'.$key.'} = ';
111 $accessor .= $attribute->has_builder
113 : ref($default) eq 'CODE'
114 ? '$default->('.$self.')'
116 $accessor .= ' if !exists '.$self.'->{'.$key.'};' . "\n";
119 if ($attribute->should_auto_deref) {
120 if ($attribute->type_constraint eq 'ArrayRef') {
121 $accessor .= 'if (wantarray) {
122 return @{ '.$self.'->{'.$key.'} || [] };
126 $accessor .= 'if (wantarray) {
127 return %{ '.$self.'->{'.$key.'} || {} };
132 $accessor .= 'return '.$self.'->{'.$key.'};
135 my $sub = eval $accessor;
140 sub generate_predicate {
141 my $attribute = shift;
142 my $key = $attribute->inlined_name;
144 my $predicate = 'sub { exists($_[0]->{'.$key.'}) }';
146 my $sub = eval $predicate;
151 sub generate_clearer {
152 my $attribute = shift;
153 my $key = $attribute->inlined_name;
155 my $clearer = 'sub { delete($_[0]->{'.$key.'}) }';
157 my $sub = eval $clearer;
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 $method;
185 my ($self, $class, $name, %args) = @_;
188 $args{associated_class} = $class;
190 %args = $self->canonicalize_args($name, %args);
191 $self->validate_args($name, \%args);
193 $args{type_constraint} = delete $args{isa}
194 if exists $args{isa};
196 my $attribute = $self->new(%args);
198 $attribute->_create_args(\%args);
200 $class->add_attribute($attribute);
202 # install an accessor
203 if ($attribute->_is_metadata eq 'rw' || $attribute->_is_metadata eq 'ro') {
204 my $accessor = $attribute->generate_accessor;
205 $class->add_method($name => $accessor);
208 for my $method (qw/predicate clearer/) {
209 my $predicate = "has_$method";
210 if ($attribute->$predicate) {
211 my $generator = "generate_$method";
212 my $coderef = $attribute->$generator;
213 $class->add_method($attribute->$method => $coderef);
217 if ($attribute->has_handles) {
218 my $method_map = $attribute->generate_handles;
219 for my $method_name (keys %$method_map) {
220 $class->add_method($method_name => $method_map->{$method_name});
227 sub canonicalize_args {
232 if ($args{lazy_build}) {
235 $args{builder} = "_build_${name}"
236 if !exists($args{builder});
238 $args{clearer} = "_clear${name}" if !exists($args{clearer});
239 $args{predicate} = "_has${name}" if !exists($args{predicate});
242 $args{clearer} = "clear_${name}" if !exists($args{clearer});
243 $args{predicate} = "has_${name}" if !exists($args{predicate});
255 confess "You can not use lazy_build and default for the same attribute ($name)"
256 if $args->{lazy_build} && exists $args->{default};
258 confess "You cannot have lazy attribute ($name) without specifying a default value for it"
260 && !exists($args->{default})
261 && !exists($args->{builder});
263 confess "References are not allowed as default values, you must wrap the default of '$name' in a CODE reference (ex: sub { [] } and not [])"
264 if ref($args->{default})
265 && ref($args->{default}) ne 'CODE';
267 confess "You cannot auto-dereference without specifying a type constraint on attribute ($name)"
268 if $args->{auto_deref} && !exists($args->{isa});
270 confess "You cannot auto-dereference anything other than a ArrayRef or HashRef on attribute ($name)"
271 if $args->{auto_deref}
272 && $args->{isa} ne 'ArrayRef'
273 && $args->{isa} ne 'HashRef';
275 if ($args->{trigger}) {
276 if (ref($args->{trigger}) eq 'HASH') {
277 Carp::carp "HASH-based form of trigger has been removed. Only the coderef form of triggers are now supported.";
280 confess "Trigger must be a CODE ref on attribute ($name)"
281 if ref($args->{trigger}) ne 'CODE';
287 sub find_type_constraint {
289 my $type = $self->type_constraint;
293 my $checker = Mouse::TypeRegistry->optimized_constraints->{$type};
294 return $checker if $checker;
296 return sub { blessed($_) && blessed($_) eq $type };
299 sub verify_type_constraint {
303 my $type = $self->type_constraint
305 my $constraint = $self->find_type_constraint;
307 return 1 if $constraint->($_);
309 my $name = $self->name;
310 my $display = defined($_) ? overload::StrVal($_) : 'undef';
311 Carp::confess("Attribute ($name) does not pass the type constraint because: Validation failed for \'$type\' failed with value $display");
314 sub _canonicalize_handles {
318 if (ref($handles) eq 'HASH') {
321 elsif (ref($handles) eq 'ARRAY') {
322 return map { $_ => $_ } @$handles;
325 confess "Unable to canonicalize the 'handles' option with $handles";
333 my %args = ($self->get_parent_args($class, $name), @_);
335 $self->create($class, $name, %args);
338 sub get_parent_args {
343 for my $super ($class->linearized_isa) {
344 my $super_attr = $super->can("meta") && $super->meta->get_attribute($name)
346 return %{ $super_attr->_create_args };
349 confess "Could not find an attribute by the name of '$name' to inherit from";
358 Mouse::Meta::Attribute - attribute metaclass
362 =head2 new %args -> Mouse::Meta::Attribute
364 Instantiates a new Mouse::Meta::Attribute. Does nothing else.
366 =head2 create OwnerClass, AttributeName, %args -> Mouse::Meta::Attribute
368 Creates a new attribute in OwnerClass. Accessors and helper methods are
369 installed. Some error checking is done.
371 =head2 name -> AttributeName
373 =head2 associated_class -> OwnerClass
375 =head2 is_required -> Bool
377 =head2 default -> Item
379 =head2 has_default -> Bool
381 =head2 is_lazy -> Bool
383 =head2 predicate -> MethodName | Undef
385 =head2 has_predicate -> Bool
387 =head2 clearer -> MethodName | Undef
389 =head2 has_clearer -> Bool
391 =head2 handles -> { LocalName => RemoteName }
393 =head2 has_handles -> Bool
395 =head2 is_weak_ref -> Bool
397 =head2 init_arg -> Str
399 =head2 type_constraint -> Str
401 =head2 has_type_constraint -> Bool
403 =head2 trigger => CODE | Undef
405 =head2 has_trigger -> Bool
407 =head2 builder => MethodName | Undef
409 =head2 has_builder -> Bool
411 =head2 is_lazy_build => Bool
413 =head2 should_auto_deref -> Bool
415 Informational methods.
417 =head2 generate_accessor -> CODE
419 Creates a new code reference for the attribute's accessor.
421 =head2 generate_predicate -> CODE
423 Creates a new code reference for the attribute's predicate.
425 =head2 generate_clearer -> CODE
427 Creates a new code reference for the attribute's clearer.
429 =head2 generate_handles -> { MethodName => CODE }
431 Creates a new code reference for each of the attribute's handles methods.
433 =head2 find_type_constraint -> CODE
435 Returns a code reference which can be used to check that a given value passes
436 this attribute's type constraint;
438 =head2 verify_type_constraint Item -> 1 | ERROR
440 Checks that the given value passes this attribute's type constraint. Returns 1
441 on success, otherwise C<confess>es.
443 =head2 canonicalize_args Name, %args -> %args
445 Canonicalizes some arguments to create. In particular, C<lazy_build> is
446 canonicalized into C<lazy>, C<builder>, etc.
448 =head2 validate_args Name, \%args -> 1 | ERROR
450 Checks that the arguments to create the attribute (ie those specified by
453 =head2 clone_parent OwnerClass, AttributeName, %args -> Mouse::Meta::Attribute
455 Creates a new attribute in OwnerClass, inheriting options from parent classes.
456 Accessors and helper methods are installed. Some error checking is done.
458 =head2 get_parent_args OwnerClass, AttributeName -> Hash
460 Returns the options that the parent class of C<OwnerClass> used for attribute