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;
72 my $key = $attribute->inlined_name;
74 my $accessor = "sub {\n";
75 if ($attribute->_is_metadata eq 'rw') {
76 $accessor .= 'if (scalar(@_) >= 2) {
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 && !$attribute->should_auto_deref;
92 if ($attribute->is_weak_ref) {
93 $accessor .= 'weaken('.$self.'->{'.$key.'}) if ref('.$self.'->{'.$key.'});' . "\n";
97 $accessor .= '$trigger->('.$self.', '.$value.', $attribute);' . "\n";
103 $accessor .= 'confess "Cannot assign a value to a read-only accessor" if scalar(@_) >= 2;' . "\n";
106 if ($attribute->is_lazy) {
107 $accessor .= $self.'->{'.$key.'} = ';
109 $accessor .= $attribute->has_builder
111 : ref($default) eq 'CODE'
112 ? '$default->('.$self.')'
114 $accessor .= ' if !exists '.$self.'->{'.$key.'};' . "\n";
117 if ($attribute->should_auto_deref) {
118 if ($attribute->type_constraint eq 'ArrayRef') {
119 $accessor .= 'if (wantarray) {
120 return @{ '.$self.'->{'.$key.'} || [] };
124 $accessor .= 'if (wantarray) {
125 return %{ '.$self.'->{'.$key.'} || {} };
130 $accessor .= 'return '.$self.'->{'.$key.'};
133 my $sub = eval $accessor;
138 sub generate_predicate {
139 my $attribute = shift;
140 my $key = $attribute->inlined_name;
142 my $predicate = 'sub { exists($_[0]->{'.$key.'}) }';
144 my $sub = eval $predicate;
149 sub generate_clearer {
150 my $attribute = shift;
151 my $key = $attribute->inlined_name;
153 my $clearer = 'sub { delete($_[0]->{'.$key.'}) }';
155 my $sub = eval $clearer;
160 sub generate_handles {
161 my $attribute = shift;
162 my $reader = $attribute->name;
163 my %handles = $attribute->_canonicalize_handles($attribute->handles);
167 for my $local_method (keys %handles) {
168 my $remote_method = $handles{$local_method};
172 $self->$reader->$remote_method(@_)
175 $method_map{$local_method} = eval $method;
183 my ($self, $class, $name, %args) = @_;
186 $args{associated_class} = $class;
188 %args = $self->canonicalize_args($name, %args);
189 $self->validate_args($name, \%args);
191 $args{type_constraint} = delete $args{isa}
192 if exists $args{isa};
194 my $attribute = $self->new(%args);
196 $attribute->_create_args(\%args);
198 $class->add_attribute($attribute);
200 # install an accessor
201 if ($attribute->_is_metadata eq 'rw' || $attribute->_is_metadata eq 'ro') {
202 my $accessor = $attribute->generate_accessor;
203 $class->add_method($name => $accessor);
206 for my $method (qw/predicate clearer/) {
207 my $predicate = "has_$method";
208 if ($attribute->$predicate) {
209 my $generator = "generate_$method";
210 my $coderef = $attribute->$generator;
211 $class->add_method($attribute->$method => $coderef);
215 if ($attribute->has_handles) {
216 my $method_map = $attribute->generate_handles;
217 for my $method_name (keys %$method_map) {
218 $class->add_method($method_name => $method_map->{$method_name});
225 sub canonicalize_args {
230 if ($args{lazy_build}) {
233 $args{builder} = "_build_${name}"
234 if !exists($args{builder});
236 $args{clearer} = "_clear${name}" if !exists($args{clearer});
237 $args{predicate} = "_has${name}" if !exists($args{predicate});
240 $args{clearer} = "clear_${name}" if !exists($args{clearer});
241 $args{predicate} = "has_${name}" if !exists($args{predicate});
253 confess "You can not use lazy_build and default for the same attribute ($name)"
254 if $args->{lazy_build} && exists $args->{default};
256 confess "You cannot have lazy attribute ($name) without specifying a default value for it"
258 && !exists($args->{default})
259 && !exists($args->{builder});
261 confess "References are not allowed as default values, you must wrap the default of '$name' in a CODE reference (ex: sub { [] } and not [])"
262 if ref($args->{default})
263 && ref($args->{default}) ne 'CODE';
265 confess "You cannot auto-dereference without specifying a type constraint on attribute ($name)"
266 if $args->{auto_deref} && !exists($args->{isa});
268 confess "You cannot auto-dereference anything other than a ArrayRef or HashRef on attribute ($name)"
269 if $args->{auto_deref}
270 && $args->{isa} ne 'ArrayRef'
271 && $args->{isa} ne 'HashRef';
273 if ($args->{trigger}) {
274 if (ref($args->{trigger}) eq 'HASH') {
275 Carp::carp "HASH-based form of trigger has been removed. Only the coderef form of triggers are now supported.";
278 confess "Trigger must be a CODE ref on attribute ($name)"
279 if ref($args->{trigger}) ne 'CODE';
285 sub find_type_constraint {
287 my $type = $self->type_constraint;
291 my $checker = Mouse::TypeRegistry->optimized_constraints->{$type};
292 return $checker if $checker;
294 return sub { blessed($_) && blessed($_) eq $type };
297 sub verify_type_constraint {
301 my $type = $self->type_constraint
303 my $constraint = $self->find_type_constraint;
305 return 1 if $constraint->($_);
307 my $name = $self->name;
308 my $display = defined($_) ? overload::StrVal($_) : 'undef';
309 Carp::confess("Attribute ($name) does not pass the type constraint because: Validation failed for \'$type\' failed with value $display");
312 sub _canonicalize_handles {
316 if (ref($handles) eq 'HASH') {
319 elsif (ref($handles) eq 'ARRAY') {
320 return map { $_ => $_ } @$handles;
323 confess "Unable to canonicalize the 'handles' option with $handles";
331 my %args = ($self->get_parent_args($class, $name), @_);
333 $self->create($class, $name, %args);
336 sub get_parent_args {
341 for my $super ($class->linearized_isa) {
342 my $super_attr = $super->can("meta") && $super->meta->get_attribute($name)
344 return %{ $super_attr->_create_args };
347 confess "Could not find an attribute by the name of '$name' to inherit from";
356 Mouse::Meta::Attribute - attribute metaclass
360 =head2 new %args -> Mouse::Meta::Attribute
362 Instantiates a new Mouse::Meta::Attribute. Does nothing else.
364 =head2 create OwnerClass, AttributeName, %args -> Mouse::Meta::Attribute
366 Creates a new attribute in OwnerClass. Accessors and helper methods are
367 installed. Some error checking is done.
369 =head2 name -> AttributeName
371 =head2 associated_class -> OwnerClass
373 =head2 is_required -> Bool
375 =head2 default -> Item
377 =head2 has_default -> Bool
379 =head2 is_lazy -> Bool
381 =head2 predicate -> MethodName | Undef
383 =head2 has_predicate -> Bool
385 =head2 clearer -> MethodName | Undef
387 =head2 has_clearer -> Bool
389 =head2 handles -> { LocalName => RemoteName }
391 =head2 has_handles -> Bool
393 =head2 is_weak_ref -> Bool
395 =head2 init_arg -> Str
397 =head2 type_constraint -> Str
399 =head2 has_type_constraint -> Bool
401 =head2 trigger => CODE | Undef
403 =head2 has_trigger -> Bool
405 =head2 builder => MethodName | Undef
407 =head2 has_builder -> Bool
409 =head2 is_lazy_build => Bool
411 =head2 should_auto_deref -> Bool
413 Informational methods.
415 =head2 generate_accessor -> CODE
417 Creates a new code reference for the attribute's accessor.
419 =head2 generate_predicate -> CODE
421 Creates a new code reference for the attribute's predicate.
423 =head2 generate_clearer -> CODE
425 Creates a new code reference for the attribute's clearer.
427 =head2 generate_handles -> { MethodName => CODE }
429 Creates a new code reference for each of the attribute's handles methods.
431 =head2 find_type_constraint -> CODE
433 Returns a code reference which can be used to check that a given value passes
434 this attribute's type constraint;
436 =head2 verify_type_constraint Item -> 1 | ERROR
438 Checks that the given value passes this attribute's type constraint. Returns 1
439 on success, otherwise C<confess>es.
441 =head2 canonicalize_args Name, %args -> %args
443 Canonicalizes some arguments to create. In particular, C<lazy_build> is
444 canonicalized into C<lazy>, C<builder>, etc.
446 =head2 validate_args Name, \%args -> 1 | ERROR
448 Checks that the arguments to create the attribute (ie those specified by
451 =head2 clone_parent OwnerClass, AttributeName, %args -> Mouse::Meta::Attribute
453 Creates a new attribute in OwnerClass, inheriting options from parent classes.
454 Accessors and helper methods are installed. Some error checking is done.
456 =head2 get_parent_args OwnerClass, AttributeName -> Hash
458 Returns the options that the parent class of C<OwnerClass> used for attribute