Commit | Line | Data |
c0e30cf5 |
1 | |
2 | package Moose::Meta::Attribute; |
3 | |
4 | use strict; |
5 | use warnings; |
6 | |
78cd1d3b |
7 | use Scalar::Util 'blessed', 'weaken', 'reftype'; |
a15dff8d |
8 | use Carp 'confess'; |
a909a4df |
9 | use overload (); |
a15dff8d |
10 | |
18ea2bcc |
11 | our $VERSION = '0.12'; |
d44714be |
12 | our $AUTHORITY = 'cpan:STEVAN'; |
78cd1d3b |
13 | |
8ee73eeb |
14 | use Moose::Meta::Method::Accessor; |
a3c7e2fe |
15 | use Moose::Util::TypeConstraints (); |
bc1e29b5 |
16 | |
c0e30cf5 |
17 | use base 'Class::MOP::Attribute'; |
18 | |
452bac1b |
19 | # options which are not directly used |
20 | # but we store them for metadata purposes |
98aae381 |
21 | __PACKAGE__->meta->add_attribute('isa' => (reader => '_isa_metadata')); |
22 | __PACKAGE__->meta->add_attribute('does' => (reader => '_does_metadata')); |
23 | __PACKAGE__->meta->add_attribute('is' => (reader => '_is_metadata')); |
452bac1b |
24 | |
25 | # these are actual options for the attrs |
1a563243 |
26 | __PACKAGE__->meta->add_attribute('required' => (reader => 'is_required' )); |
27 | __PACKAGE__->meta->add_attribute('lazy' => (reader => 'is_lazy' )); |
28 | __PACKAGE__->meta->add_attribute('coerce' => (reader => 'should_coerce' )); |
29 | __PACKAGE__->meta->add_attribute('weak_ref' => (reader => 'is_weak_ref' )); |
30 | __PACKAGE__->meta->add_attribute('auto_deref' => (reader => 'should_auto_deref')); |
82168dbb |
31 | __PACKAGE__->meta->add_attribute('type_constraint' => ( |
32 | reader => 'type_constraint', |
33 | predicate => 'has_type_constraint', |
34 | )); |
8c9d74e7 |
35 | __PACKAGE__->meta->add_attribute('trigger' => ( |
36 | reader => 'trigger', |
37 | predicate => 'has_trigger', |
38 | )); |
452bac1b |
39 | __PACKAGE__->meta->add_attribute('handles' => ( |
40 | reader => 'handles', |
41 | predicate => 'has_handles', |
42 | )); |
ddbdc0cb |
43 | __PACKAGE__->meta->add_attribute('documentation' => ( |
44 | reader => 'documentation', |
45 | predicate => 'has_documentation', |
46 | )); |
82168dbb |
47 | |
78cd1d3b |
48 | sub new { |
49 | my ($class, $name, %options) = @_; |
1d768fb1 |
50 | $class->_process_options($name, \%options); |
98aae381 |
51 | return $class->SUPER::new($name, %options); |
1d768fb1 |
52 | } |
53 | |
ce0e8d63 |
54 | sub clone_and_inherit_options { |
55 | my ($self, %options) = @_; |
83cc9094 |
56 | # you can change default, required, coerce, documentation and lazy |
ce0e8d63 |
57 | my %actual_options; |
83cc9094 |
58 | foreach my $legal_option (qw(default coerce required documentation lazy)) { |
ce0e8d63 |
59 | if (exists $options{$legal_option}) { |
60 | $actual_options{$legal_option} = $options{$legal_option}; |
61 | delete $options{$legal_option}; |
62 | } |
63 | } |
83cc9094 |
64 | |
65 | # handles can only be added, not changed |
66 | if ($options{handles}) { |
67 | confess "You can only add the 'handles' option, you cannot change it" |
68 | if $self->has_handles; |
69 | $actual_options{handles} = $options{handles}; |
70 | delete $options{handles}; |
71 | } |
72 | |
fcb7afc2 |
73 | # isa can be changed, but only if the |
74 | # new type is a subtype |
ce0e8d63 |
75 | if ($options{isa}) { |
76 | my $type_constraint; |
77 | if (blessed($options{isa}) && $options{isa}->isa('Moose::Meta::TypeConstraint')) { |
78 | $type_constraint = $options{isa}; |
79 | } |
80 | else { |
81 | $type_constraint = Moose::Util::TypeConstraints::find_type_constraint($options{isa}); |
82 | (defined $type_constraint) |
83 | || confess "Could not find the type constraint '" . $options{isa} . "'"; |
84 | } |
2a0f3bd3 |
85 | # NOTE: |
86 | # check here to see if the new type |
87 | # is a subtype of the old one |
ce0e8d63 |
88 | ($type_constraint->is_subtype_of($self->type_constraint->name)) |
89 | || confess "New type constraint setting must be a subtype of inherited one" |
2a0f3bd3 |
90 | # iff we have a type constraint that is ... |
ce0e8d63 |
91 | if $self->has_type_constraint; |
2a0f3bd3 |
92 | # then we use it :) |
ce0e8d63 |
93 | $actual_options{type_constraint} = $type_constraint; |
94 | delete $options{isa}; |
95 | } |
96 | (scalar keys %options == 0) |
97 | || confess "Illegal inherited options => (" . (join ', ' => keys %options) . ")"; |
98 | $self->clone(%actual_options); |
1d768fb1 |
99 | } |
100 | |
101 | sub _process_options { |
102 | my ($class, $name, $options) = @_; |
452bac1b |
103 | |
1d768fb1 |
104 | if (exists $options->{is}) { |
105 | if ($options->{is} eq 'ro') { |
df492bba |
106 | $options->{reader} ||= $name; |
1d768fb1 |
107 | (!exists $options->{trigger}) |
8c9d74e7 |
108 | || confess "Cannot have a trigger on a read-only attribute"; |
78cd1d3b |
109 | } |
1d768fb1 |
110 | elsif ($options->{is} eq 'rw') { |
452bac1b |
111 | $options->{accessor} = $name; |
98aae381 |
112 | ((reftype($options->{trigger}) || '') eq 'CODE') |
113 | || confess "Trigger must be a CODE ref" |
114 | if exists $options->{trigger}; |
452bac1b |
115 | } |
116 | else { |
117 | confess "I do not understand this option (is => " . $options->{is} . ")" |
78cd1d3b |
118 | } |
119 | } |
120 | |
1d768fb1 |
121 | if (exists $options->{isa}) { |
02a0fb52 |
122 | |
1d768fb1 |
123 | if (exists $options->{does}) { |
124 | if (eval { $options->{isa}->can('does') }) { |
125 | ($options->{isa}->does($options->{does})) |
02a0fb52 |
126 | || confess "Cannot have an isa option and a does option if the isa does not do the does"; |
127 | } |
7eaef7ad |
128 | else { |
129 | confess "Cannot have an isa option which cannot ->does()"; |
130 | } |
02a0fb52 |
131 | } |
132 | |
78cd1d3b |
133 | # allow for anon-subtypes here ... |
1d768fb1 |
134 | if (blessed($options->{isa}) && $options->{isa}->isa('Moose::Meta::TypeConstraint')) { |
135 | $options->{type_constraint} = $options->{isa}; |
78cd1d3b |
136 | } |
137 | else { |
c07af9d2 |
138 | |
1d768fb1 |
139 | if ($options->{isa} =~ /\|/) { |
140 | my @type_constraints = split /\s*\|\s*/ => $options->{isa}; |
141 | $options->{type_constraint} = Moose::Util::TypeConstraints::create_type_constraint_union( |
c07af9d2 |
142 | @type_constraints |
78cd1d3b |
143 | ); |
c07af9d2 |
144 | } |
145 | else { |
146 | # otherwise assume it is a constraint |
1d768fb1 |
147 | my $constraint = Moose::Util::TypeConstraints::find_type_constraint($options->{isa}); |
c07af9d2 |
148 | # if the constraing it not found .... |
149 | unless (defined $constraint) { |
150 | # assume it is a foreign class, and make |
151 | # an anon constraint for it |
152 | $constraint = Moose::Util::TypeConstraints::subtype( |
153 | 'Object', |
1d768fb1 |
154 | Moose::Util::TypeConstraints::where { $_->isa($options->{isa}) } |
c07af9d2 |
155 | ); |
156 | } |
1d768fb1 |
157 | $options->{type_constraint} = $constraint; |
c07af9d2 |
158 | } |
78cd1d3b |
159 | } |
160 | } |
1d768fb1 |
161 | elsif (exists $options->{does}) { |
02a0fb52 |
162 | # allow for anon-subtypes here ... |
1d768fb1 |
163 | if (blessed($options->{does}) && $options->{does}->isa('Moose::Meta::TypeConstraint')) { |
164 | $options->{type_constraint} = $options->{isa}; |
02a0fb52 |
165 | } |
166 | else { |
167 | # otherwise assume it is a constraint |
1d768fb1 |
168 | my $constraint = Moose::Util::TypeConstraints::find_type_constraint($options->{does}); |
02a0fb52 |
169 | # if the constraing it not found .... |
170 | unless (defined $constraint) { |
171 | # assume it is a foreign class, and make |
172 | # an anon constraint for it |
173 | $constraint = Moose::Util::TypeConstraints::subtype( |
174 | 'Role', |
1d768fb1 |
175 | Moose::Util::TypeConstraints::where { $_->does($options->{does}) } |
02a0fb52 |
176 | ); |
177 | } |
1d768fb1 |
178 | $options->{type_constraint} = $constraint; |
02a0fb52 |
179 | } |
180 | } |
78cd1d3b |
181 | |
1d768fb1 |
182 | if (exists $options->{coerce} && $options->{coerce}) { |
183 | (exists $options->{type_constraint}) |
3ec7b7a3 |
184 | || confess "You cannot have coercion without specifying a type constraint"; |
4b598ea3 |
185 | confess "You cannot have a weak reference to a coerced value" |
1d768fb1 |
186 | if $options->{weak_ref}; |
ca01a97b |
187 | } |
78cd1d3b |
188 | |
536f0b17 |
189 | if (exists $options->{auto_deref} && $options->{auto_deref}) { |
190 | (exists $options->{type_constraint}) |
191 | || confess "You cannot auto-dereference without specifying a type constraint"; |
94b8bbb8 |
192 | ($options->{type_constraint}->is_a_type_of('ArrayRef') || |
193 | $options->{type_constraint}->is_a_type_of('HashRef')) |
536f0b17 |
194 | || confess "You cannot auto-dereference anything other than a ArrayRef or HashRef"; |
195 | } |
196 | |
1d768fb1 |
197 | if (exists $options->{lazy} && $options->{lazy}) { |
198 | (exists $options->{default}) |
ca01a97b |
199 | || confess "You cannot have lazy attribute without specifying a default value for it"; |
1d768fb1 |
200 | } |
78cd1d3b |
201 | } |
c0e30cf5 |
202 | |
d500266f |
203 | sub initialize_instance_slot { |
ddd0ec20 |
204 | my ($self, $meta_instance, $instance, $params) = @_; |
d500266f |
205 | my $init_arg = $self->init_arg(); |
206 | # try to fetch the init arg from the %params ... |
ddd0ec20 |
207 | |
d500266f |
208 | my $val; |
209 | if (exists $params->{$init_arg}) { |
210 | $val = $params->{$init_arg}; |
ab859145 |
211 | |
212 | if (!defined $val && $self->is_required) { |
213 | confess "Attribute (" . $self->name . ") is required and cannot be undef"; |
214 | } |
d500266f |
215 | } |
216 | else { |
217 | # skip it if it's lazy |
218 | return if $self->is_lazy; |
219 | # and die if it's required and doesn't have a default value |
220 | confess "Attribute (" . $self->name . ") is required" |
221 | if $self->is_required && !$self->has_default; |
222 | } |
ddd0ec20 |
223 | |
d500266f |
224 | # if nothing was in the %params, we can use the |
225 | # attribute's default value (if it has one) |
226 | if (!defined $val && $self->has_default) { |
227 | $val = $self->default($instance); |
ab859145 |
228 | } |
d7611a4a |
229 | |
7a5ebc40 |
230 | if (defined $val || $self->has_default) { |
d500266f |
231 | if ($self->has_type_constraint) { |
c07af9d2 |
232 | my $type_constraint = $self->type_constraint; |
233 | if ($self->should_coerce && $type_constraint->has_coercion) { |
0a5bd159 |
234 | $val = $type_constraint->coerce($val); |
d500266f |
235 | } |
c07af9d2 |
236 | (defined($type_constraint->check($val))) |
237 | || confess "Attribute (" . |
238 | $self->name . |
8449e6e7 |
239 | ") does not pass the type constraint (" . |
c07af9d2 |
240 | $type_constraint->name . |
a909a4df |
241 | ") with '" . |
242 | (defined $val |
8ac5969a |
243 | ? (blessed($val) && overload::Overloaded($val) |
a909a4df |
244 | ? overload::StrVal($val) |
245 | : $val) |
246 | : 'undef') . |
247 | "'"; |
d500266f |
248 | } |
249 | } |
ddd0ec20 |
250 | |
ac1ef2f9 |
251 | $meta_instance->set_slot_value($instance, $self->name, $val); |
252 | $meta_instance->weaken_slot_value($instance, $self->name) |
253 | if ref $val && $self->is_weak_ref; |
d500266f |
254 | } |
255 | |
d617b644 |
256 | ## Slot management |
9e93dd19 |
257 | |
946289d1 |
258 | sub set_value { |
259 | my ($self, $instance, $value) = @_; |
260 | |
261 | my $attr_name = $self->name; |
262 | |
263 | if ($self->is_required) { |
264 | defined($value) |
265 | || confess "Attribute ($attr_name) is required, so cannot be set to undef"; |
266 | } |
267 | |
268 | if ($self->has_type_constraint) { |
269 | |
270 | my $type_constraint = $self->type_constraint; |
271 | |
272 | if ($self->should_coerce) { |
273 | $value = $type_constraint->coerce($value); |
274 | } |
275 | defined($type_constraint->_compiled_type_constraint->($value)) |
276 | || confess "Attribute ($attr_name) does not pass the type constraint (" |
a909a4df |
277 | . $type_constraint->name |
278 | . ") with " |
279 | . (defined($value) |
8ac5969a |
280 | ? ("'" . |
281 | (blessed($value) && overload::Overloaded($value) |
282 | ? overload::StrVal($value) |
283 | : $value) |
284 | . "'") |
a909a4df |
285 | : "undef") |
946289d1 |
286 | if defined($value); |
287 | } |
288 | |
289 | my $meta_instance = Class::MOP::Class->initialize(blessed($instance)) |
290 | ->get_meta_instance; |
291 | |
292 | $meta_instance->set_slot_value($instance, $attr_name, $value); |
293 | |
294 | if (ref $value && $self->is_weak_ref) { |
295 | $meta_instance->weaken_slot_value($instance, $attr_name); |
296 | } |
297 | |
298 | if ($self->has_trigger) { |
299 | $self->trigger->($instance, $value, $self); |
300 | } |
301 | } |
302 | |
303 | sub get_value { |
304 | my ($self, $instance) = @_; |
305 | |
306 | if ($self->is_lazy) { |
307 | unless ($self->has_value($instance)) { |
308 | if ($self->has_default) { |
309 | my $default = $self->default($instance); |
310 | $self->set_value($instance, $default); |
311 | } |
312 | else { |
313 | $self->set_value($instance, undef); |
314 | } |
315 | } |
316 | } |
317 | |
318 | if ($self->should_auto_deref) { |
319 | |
320 | my $type_constraint = $self->type_constraint; |
321 | |
322 | if ($type_constraint->is_a_type_of('ArrayRef')) { |
323 | my $rv = $self->SUPER::get_value($instance); |
324 | return unless defined $rv; |
325 | return wantarray ? @{ $rv } : $rv; |
326 | } |
327 | elsif ($type_constraint->is_a_type_of('HashRef')) { |
328 | my $rv = $self->SUPER::get_value($instance); |
329 | return unless defined $rv; |
330 | return wantarray ? %{ $rv } : $rv; |
331 | } |
332 | else { |
333 | confess "Can not auto de-reference the type constraint '" . $type_constraint->name . "'"; |
334 | } |
335 | |
336 | } |
337 | else { |
338 | |
339 | return $self->SUPER::get_value($instance); |
340 | } |
341 | } |
a15dff8d |
342 | |
d617b644 |
343 | ## installing accessors |
c0e30cf5 |
344 | |
d617b644 |
345 | sub accessor_metaclass { 'Moose::Meta::Method::Accessor' } |
d7f17ebb |
346 | |
452bac1b |
347 | sub install_accessors { |
348 | my $self = shift; |
349 | $self->SUPER::install_accessors(@_); |
350 | |
351 | if ($self->has_handles) { |
352 | |
353 | # NOTE: |
354 | # Here we canonicalize the 'handles' option |
355 | # this will sort out any details and always |
356 | # return an hash of methods which we want |
357 | # to delagate to, see that method for details |
358 | my %handles = $self->_canonicalize_handles(); |
359 | |
360 | # find the name of the accessor for this attribute |
361 | my $accessor_name = $self->reader || $self->accessor; |
362 | (defined $accessor_name) |
363 | || confess "You cannot install delegation without a reader or accessor for the attribute"; |
364 | |
365 | # make sure we handle HASH accessors correctly |
366 | ($accessor_name) = keys %{$accessor_name} |
367 | if ref($accessor_name) eq 'HASH'; |
368 | |
369 | # install the delegation ... |
370 | my $associated_class = $self->associated_class; |
371 | foreach my $handle (keys %handles) { |
372 | my $method_to_call = $handles{$handle}; |
373 | |
374 | (!$associated_class->has_method($handle)) |
375 | || confess "You cannot overwrite a locally defined method ($handle) with a delegation"; |
376 | |
d022f632 |
377 | # NOTE: |
378 | # handles is not allowed to delegate |
379 | # any of these methods, as they will |
380 | # override the ones in your class, which |
381 | # is almost certainly not what you want. |
382 | next if $handle =~ /^BUILD|DEMOLISH$/ || Moose::Object->can($handle); |
383 | |
452bac1b |
384 | if ((reftype($method_to_call) || '') eq 'CODE') { |
385 | $associated_class->add_method($handle => $method_to_call); |
386 | } |
387 | else { |
388 | $associated_class->add_method($handle => sub { |
b805c70c |
389 | # FIXME |
390 | # we should check for lack of |
391 | # a callable return value from |
392 | # the accessor here |
cbe25729 |
393 | my $proxy = (shift)->$accessor_name(); |
394 | @_ = ($proxy, @_); |
395 | goto &{ $proxy->can($method_to_call)}; |
452bac1b |
396 | }); |
397 | } |
398 | } |
399 | } |
400 | |
401 | return; |
402 | } |
403 | |
98aae381 |
404 | # private methods to help delegation ... |
405 | |
452bac1b |
406 | sub _canonicalize_handles { |
407 | my $self = shift; |
408 | my $handles = $self->handles; |
c84f324f |
409 | if (my $handle_type = ref($handles)) { |
410 | if ($handle_type eq 'HASH') { |
411 | return %{$handles}; |
412 | } |
413 | elsif ($handle_type eq 'ARRAY') { |
414 | return map { $_ => $_ } @{$handles}; |
415 | } |
416 | elsif ($handle_type eq 'Regexp') { |
417 | ($self->has_type_constraint) |
418 | || confess "Cannot delegate methods based on a RegExpr without a type constraint (isa)"; |
419 | return map { ($_ => $_) } |
420 | grep { /$handles/ } $self->_get_delegate_method_list; |
421 | } |
422 | elsif ($handle_type eq 'CODE') { |
423 | return $handles->($self, $self->_find_delegate_metaclass); |
424 | } |
425 | else { |
426 | confess "Unable to canonicalize the 'handles' option with $handles"; |
427 | } |
452bac1b |
428 | } |
429 | else { |
c84f324f |
430 | my $role_meta = eval { $handles->meta }; |
431 | if ($@) { |
432 | confess "Unable to canonicalize the 'handles' option with $handles because : $@"; |
433 | } |
434 | |
435 | (blessed $role_meta && $role_meta->isa('Moose::Meta::Role')) |
436 | || confess "Unable to canonicalize the 'handles' option with $handles because ->meta is not a Moose::Meta::Role"; |
437 | |
438 | return map { $_ => $_ } ( |
439 | $role_meta->get_method_list, |
440 | $role_meta->get_required_method_list |
441 | ); |
452bac1b |
442 | } |
443 | } |
444 | |
445 | sub _find_delegate_metaclass { |
446 | my $self = shift; |
98aae381 |
447 | if (my $class = $self->_isa_metadata) { |
452bac1b |
448 | # if the class does have |
449 | # a meta method, use it |
450 | return $class->meta if $class->can('meta'); |
451 | # otherwise we might be |
452 | # dealing with a non-Moose |
453 | # class, and need to make |
454 | # our own metaclass |
455 | return Moose::Meta::Class->initialize($class); |
456 | } |
98aae381 |
457 | elsif (my $role = $self->_does_metadata) { |
452bac1b |
458 | # our role will always have |
459 | # a meta method |
98aae381 |
460 | return $role->meta; |
452bac1b |
461 | } |
462 | else { |
463 | confess "Cannot find delegate metaclass for attribute " . $self->name; |
464 | } |
465 | } |
466 | |
467 | sub _get_delegate_method_list { |
468 | my $self = shift; |
469 | my $meta = $self->_find_delegate_metaclass; |
470 | if ($meta->isa('Class::MOP::Class')) { |
093b12c2 |
471 | return map { $_->{name} } # NOTE: !never! delegate &meta |
472 | grep { $_->{class} ne 'Moose::Object' && $_->{name} ne 'meta' } |
452bac1b |
473 | $meta->compute_all_applicable_methods; |
474 | } |
475 | elsif ($meta->isa('Moose::Meta::Role')) { |
476 | return $meta->get_method_list; |
477 | } |
478 | else { |
479 | confess "Unable to recognize the delegate metaclass '$meta'"; |
480 | } |
481 | } |
482 | |
c0e30cf5 |
483 | 1; |
484 | |
485 | __END__ |
486 | |
487 | =pod |
488 | |
489 | =head1 NAME |
490 | |
6ba6d68c |
491 | Moose::Meta::Attribute - The Moose attribute metaclass |
c0e30cf5 |
492 | |
493 | =head1 DESCRIPTION |
494 | |
e522431d |
495 | This is a subclass of L<Class::MOP::Attribute> with Moose specific |
6ba6d68c |
496 | extensions. |
497 | |
498 | For the most part, the only time you will ever encounter an |
499 | instance of this class is if you are doing some serious deep |
500 | introspection. To really understand this class, you need to refer |
501 | to the L<Class::MOP::Attribute> documentation. |
e522431d |
502 | |
c0e30cf5 |
503 | =head1 METHODS |
504 | |
6ba6d68c |
505 | =head2 Overridden methods |
506 | |
507 | These methods override methods in L<Class::MOP::Attribute> and add |
508 | Moose specific features. You can safely assume though that they |
509 | will behave just as L<Class::MOP::Attribute> does. |
510 | |
c0e30cf5 |
511 | =over 4 |
512 | |
513 | =item B<new> |
514 | |
d500266f |
515 | =item B<initialize_instance_slot> |
516 | |
452bac1b |
517 | =item B<install_accessors> |
518 | |
39b3bc94 |
519 | =item B<accessor_metaclass> |
520 | |
946289d1 |
521 | =item B<get_value> |
522 | |
523 | =item B<set_value> |
524 | |
bcbaa845 |
525 | eval { $point->meta->get_attribute('x')->set_value($point, 'fourty-two') }; |
526 | if($@) { |
527 | print "Oops: $@\n"; |
528 | } |
529 | |
530 | I<Attribute (x) does not pass the type constraint (Int) with 'fourty-two'> |
531 | |
532 | Before setting the value, a check is made on the type constraint of |
533 | the attribute, if it has one, to see if the value passes it. If the |
534 | value fails to pass, the set operation dies with a L<Carp/confess>. |
535 | |
536 | Any coercion to convert values is done before checking the type constraint. |
537 | |
538 | To check a value against a type constraint before setting it, fetch the |
539 | attribute instance using L<Moose::Meta::Attribute/find_attribute_by_name>, |
540 | fetch the type_constraint from the attribute using L<Moose::Meta::Attribute/type_constraint> |
541 | and call L<Moose::Meta::TypeConstraint/check>. See L<Moose::Cookbook::RecipeX> |
542 | for an example. |
543 | |
a15dff8d |
544 | =back |
545 | |
6ba6d68c |
546 | =head2 Additional Moose features |
547 | |
8449e6e7 |
548 | Moose attributes support type-constraint checking, weak reference |
6ba6d68c |
549 | creation and type coercion. |
550 | |
a15dff8d |
551 | =over 4 |
552 | |
9e93dd19 |
553 | =item B<clone_and_inherit_options> |
554 | |
555 | This is to support the C<has '+foo'> feature, it clones an attribute |
556 | from a superclass and allows a very specific set of changes to be made |
557 | to the attribute. |
558 | |
a15dff8d |
559 | =item B<has_type_constraint> |
560 | |
6ba6d68c |
561 | Returns true if this meta-attribute has a type constraint. |
562 | |
a15dff8d |
563 | =item B<type_constraint> |
564 | |
6ba6d68c |
565 | A read-only accessor for this meta-attribute's type constraint. For |
566 | more information on what you can do with this, see the documentation |
567 | for L<Moose::Meta::TypeConstraint>. |
a15dff8d |
568 | |
452bac1b |
569 | =item B<has_handles> |
570 | |
571 | Returns true if this meta-attribute performs delegation. |
572 | |
573 | =item B<handles> |
574 | |
575 | This returns the value which was passed into the handles option. |
576 | |
6ba6d68c |
577 | =item B<is_weak_ref> |
a15dff8d |
578 | |
02a0fb52 |
579 | Returns true if this meta-attribute produces a weak reference. |
4b598ea3 |
580 | |
ca01a97b |
581 | =item B<is_required> |
582 | |
02a0fb52 |
583 | Returns true if this meta-attribute is required to have a value. |
ca01a97b |
584 | |
585 | =item B<is_lazy> |
586 | |
02a0fb52 |
587 | Returns true if this meta-attribute should be initialized lazily. |
ca01a97b |
588 | |
589 | NOTE: lazy attributes, B<must> have a C<default> field set. |
590 | |
34a66aa3 |
591 | =item B<should_coerce> |
4b598ea3 |
592 | |
02a0fb52 |
593 | Returns true if this meta-attribute should perform type coercion. |
6ba6d68c |
594 | |
536f0b17 |
595 | =item B<should_auto_deref> |
596 | |
597 | Returns true if this meta-attribute should perform automatic |
598 | auto-dereferencing. |
599 | |
600 | NOTE: This can only be done for attributes whose type constraint is |
601 | either I<ArrayRef> or I<HashRef>. |
602 | |
8c9d74e7 |
603 | =item B<has_trigger> |
604 | |
02a0fb52 |
605 | Returns true if this meta-attribute has a trigger set. |
606 | |
8c9d74e7 |
607 | =item B<trigger> |
608 | |
02a0fb52 |
609 | This is a CODE reference which will be executed every time the |
610 | value of an attribute is assigned. The CODE ref will get two values, |
611 | the invocant and the new value. This can be used to handle I<basic> |
612 | bi-directional relations. |
613 | |
ddbdc0cb |
614 | =item B<documentation> |
615 | |
616 | This is a string which contains the documentation for this attribute. |
617 | It serves no direct purpose right now, but it might in the future |
618 | in some kind of automated documentation system perhaps. |
619 | |
620 | =item B<has_documentation> |
621 | |
622 | Returns true if this meta-attribute has any documentation. |
623 | |
c0e30cf5 |
624 | =back |
625 | |
626 | =head1 BUGS |
627 | |
628 | All complex software has bugs lurking in it, and this module is no |
629 | exception. If you find a bug please either email me, or add the bug |
630 | to cpan-RT. |
631 | |
c0e30cf5 |
632 | =head1 AUTHOR |
633 | |
634 | Stevan Little E<lt>stevan@iinteractive.comE<gt> |
635 | |
98aae381 |
636 | Yuval Kogman E<lt>nothingmuch@woobling.comE<gt> |
637 | |
c0e30cf5 |
638 | =head1 COPYRIGHT AND LICENSE |
639 | |
b77fdbed |
640 | Copyright 2006, 2007 by Infinity Interactive, Inc. |
c0e30cf5 |
641 | |
642 | L<http://www.iinteractive.com> |
643 | |
644 | This library is free software; you can redistribute it and/or modify |
645 | it under the same terms as Perl itself. |
646 | |
8a7a9c53 |
647 | =cut |