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;
69 my $is_weak = $attribute->is_weak_ref;
70 my $should_deref = $attribute->should_auto_deref;
73 my $key = $attribute->inlined_name;
75 my $accessor = "sub {\n";
76 if ($attribute->_is_metadata eq 'rw') {
77 $accessor .= 'if (scalar(@_) >= 2) {' . "\n";
82 $accessor .= 'local $_ = '.$value.';
83 unless ($constraint->()) {
84 my $display = defined($_) ? overload::StrVal($_) : "undef";
85 Carp::confess("Attribute ($name) does not pass the type constraint because: Validation failed for \'$type\' failed with value $display");
89 # if there's nothing left to do for the attribute we can return during
91 $accessor .= 'return ' if !$is_weak && !$trigger && !$should_deref;
93 $accessor .= $self.'->{'.$key.'} = '.$value.';' . "\n";
96 $accessor .= 'weaken('.$self.'->{'.$key.'}) if ref('.$self.'->{'.$key.'});' . "\n";
100 $accessor .= '$trigger->('.$self.', '.$value.', $attribute);' . "\n";
106 $accessor .= 'confess "Cannot assign a value to a read-only accessor" if scalar(@_) >= 2;' . "\n";
109 if ($attribute->is_lazy) {
110 $accessor .= $self.'->{'.$key.'} = ';
112 $accessor .= $attribute->has_builder
114 : ref($default) eq 'CODE'
115 ? '$default->('.$self.')'
117 $accessor .= ' if !exists '.$self.'->{'.$key.'};' . "\n";
121 if ($attribute->type_constraint eq 'ArrayRef') {
122 $accessor .= 'if (wantarray) {
123 return @{ '.$self.'->{'.$key.'} || [] };
127 $accessor .= 'if (wantarray) {
128 return %{ '.$self.'->{'.$key.'} || {} };
133 $accessor .= 'return '.$self.'->{'.$key.'};
136 my $sub = eval $accessor;
141 sub generate_predicate {
142 my $attribute = shift;
143 my $key = $attribute->inlined_name;
145 my $predicate = 'sub { exists($_[0]->{'.$key.'}) }';
147 my $sub = eval $predicate;
152 sub generate_clearer {
153 my $attribute = shift;
154 my $key = $attribute->inlined_name;
156 my $clearer = 'sub { delete($_[0]->{'.$key.'}) }';
158 my $sub = eval $clearer;
163 sub generate_handles {
164 my $attribute = shift;
165 my $reader = $attribute->name;
166 my %handles = $attribute->_canonicalize_handles($attribute->handles);
170 for my $local_method (keys %handles) {
171 my $remote_method = $handles{$local_method};
175 $self->$reader->$remote_method(@_)
178 $method_map{$local_method} = eval $method;
186 my ($self, $class, $name, %args) = @_;
189 $args{associated_class} = $class;
191 %args = $self->canonicalize_args($name, %args);
192 $self->validate_args($name, \%args);
194 $args{type_constraint} = delete $args{isa}
195 if exists $args{isa};
197 my $attribute = $self->new(%args);
199 $attribute->_create_args(\%args);
201 $class->add_attribute($attribute);
203 # install an accessor
204 if ($attribute->_is_metadata eq 'rw' || $attribute->_is_metadata eq 'ro') {
205 my $accessor = $attribute->generate_accessor;
206 $class->add_method($name => $accessor);
209 for my $method (qw/predicate clearer/) {
210 my $predicate = "has_$method";
211 if ($attribute->$predicate) {
212 my $generator = "generate_$method";
213 my $coderef = $attribute->$generator;
214 $class->add_method($attribute->$method => $coderef);
218 if ($attribute->has_handles) {
219 my $method_map = $attribute->generate_handles;
220 for my $method_name (keys %$method_map) {
221 $class->add_method($method_name => $method_map->{$method_name});
228 sub canonicalize_args {
233 if ($args{lazy_build}) {
236 $args{builder} = "_build_${name}"
237 if !exists($args{builder});
239 $args{clearer} = "_clear${name}" if !exists($args{clearer});
240 $args{predicate} = "_has${name}" if !exists($args{predicate});
243 $args{clearer} = "clear_${name}" if !exists($args{clearer});
244 $args{predicate} = "has_${name}" if !exists($args{predicate});
256 confess "You can not use lazy_build and default for the same attribute ($name)"
257 if $args->{lazy_build} && exists $args->{default};
259 confess "You cannot have lazy attribute ($name) without specifying a default value for it"
261 && !exists($args->{default})
262 && !exists($args->{builder});
264 confess "References are not allowed as default values, you must wrap the default of '$name' in a CODE reference (ex: sub { [] } and not [])"
265 if ref($args->{default})
266 && ref($args->{default}) ne 'CODE';
268 confess "You cannot auto-dereference without specifying a type constraint on attribute ($name)"
269 if $args->{auto_deref} && !exists($args->{isa});
271 confess "You cannot auto-dereference anything other than a ArrayRef or HashRef on attribute ($name)"
272 if $args->{auto_deref}
273 && $args->{isa} ne 'ArrayRef'
274 && $args->{isa} ne 'HashRef';
276 if ($args->{trigger}) {
277 if (ref($args->{trigger}) eq 'HASH') {
278 Carp::carp "HASH-based form of trigger has been removed. Only the coderef form of triggers are now supported.";
281 confess "Trigger must be a CODE ref on attribute ($name)"
282 if ref($args->{trigger}) ne 'CODE';
288 sub find_type_constraint {
290 my $type = $self->type_constraint;
294 my $checker = Mouse::TypeRegistry->optimized_constraints->{$type};
295 return $checker if $checker;
297 return sub { blessed($_) && blessed($_) eq $type };
300 sub verify_type_constraint {
304 my $type = $self->type_constraint
306 my $constraint = $self->find_type_constraint;
308 return 1 if $constraint->($_);
310 my $name = $self->name;
311 my $display = defined($_) ? overload::StrVal($_) : 'undef';
312 Carp::confess("Attribute ($name) does not pass the type constraint because: Validation failed for \'$type\' failed with value $display");
315 sub _canonicalize_handles {
319 if (ref($handles) eq 'HASH') {
322 elsif (ref($handles) eq 'ARRAY') {
323 return map { $_ => $_ } @$handles;
326 confess "Unable to canonicalize the 'handles' option with $handles";
334 my %args = ($self->get_parent_args($class, $name), @_);
336 $self->create($class, $name, %args);
339 sub get_parent_args {
344 for my $super ($class->linearized_isa) {
345 my $super_attr = $super->can("meta") && $super->meta->get_attribute($name)
347 return %{ $super_attr->_create_args };
350 confess "Could not find an attribute by the name of '$name' to inherit from";
359 Mouse::Meta::Attribute - attribute metaclass
363 =head2 new %args -> Mouse::Meta::Attribute
365 Instantiates a new Mouse::Meta::Attribute. Does nothing else.
367 =head2 create OwnerClass, AttributeName, %args -> Mouse::Meta::Attribute
369 Creates a new attribute in OwnerClass. Accessors and helper methods are
370 installed. Some error checking is done.
372 =head2 name -> AttributeName
374 =head2 associated_class -> OwnerClass
376 =head2 is_required -> Bool
378 =head2 default -> Item
380 =head2 has_default -> Bool
382 =head2 is_lazy -> Bool
384 =head2 predicate -> MethodName | Undef
386 =head2 has_predicate -> Bool
388 =head2 clearer -> MethodName | Undef
390 =head2 has_clearer -> Bool
392 =head2 handles -> { LocalName => RemoteName }
394 =head2 has_handles -> Bool
396 =head2 is_weak_ref -> Bool
398 =head2 init_arg -> Str
400 =head2 type_constraint -> Str
402 =head2 has_type_constraint -> Bool
404 =head2 trigger => CODE | Undef
406 =head2 has_trigger -> Bool
408 =head2 builder => MethodName | Undef
410 =head2 has_builder -> Bool
412 =head2 is_lazy_build => Bool
414 =head2 should_auto_deref -> Bool
416 Informational methods.
418 =head2 generate_accessor -> CODE
420 Creates a new code reference for the attribute's accessor.
422 =head2 generate_predicate -> CODE
424 Creates a new code reference for the attribute's predicate.
426 =head2 generate_clearer -> CODE
428 Creates a new code reference for the attribute's clearer.
430 =head2 generate_handles -> { MethodName => CODE }
432 Creates a new code reference for each of the attribute's handles methods.
434 =head2 find_type_constraint -> CODE
436 Returns a code reference which can be used to check that a given value passes
437 this attribute's type constraint;
439 =head2 verify_type_constraint Item -> 1 | ERROR
441 Checks that the given value passes this attribute's type constraint. Returns 1
442 on success, otherwise C<confess>es.
444 =head2 canonicalize_args Name, %args -> %args
446 Canonicalizes some arguments to create. In particular, C<lazy_build> is
447 canonicalized into C<lazy>, C<builder>, etc.
449 =head2 validate_args Name, \%args -> 1 | ERROR
451 Checks that the arguments to create the attribute (ie those specified by
454 =head2 clone_parent OwnerClass, AttributeName, %args -> Mouse::Meta::Attribute
456 Creates a new attribute in OwnerClass, inheriting options from parent classes.
457 Accessors and helper methods are installed. Some error checking is done.
459 =head2 get_parent_args OwnerClass, AttributeName -> Hash
461 Returns the options that the parent class of C<OwnerClass> used for attribute