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 | |
0b26305c |
11 | our $VERSION = '0.14'; |
d44714be |
12 | our $AUTHORITY = 'cpan:STEVAN'; |
78cd1d3b |
13 | |
8ee73eeb |
14 | use Moose::Meta::Method::Accessor; |
a3c7e2fe |
15 | use Moose::Util::TypeConstraints (); |
bc1e29b5 |
16 | |
c0e30cf5 |
17 | use base 'Class::MOP::Attribute'; |
18 | |
452bac1b |
19 | # options which are not directly used |
20 | # but we store them for metadata purposes |
98aae381 |
21 | __PACKAGE__->meta->add_attribute('isa' => (reader => '_isa_metadata')); |
22 | __PACKAGE__->meta->add_attribute('does' => (reader => '_does_metadata')); |
23 | __PACKAGE__->meta->add_attribute('is' => (reader => '_is_metadata')); |
452bac1b |
24 | |
25 | # these are actual options for the attrs |
1a563243 |
26 | __PACKAGE__->meta->add_attribute('required' => (reader => 'is_required' )); |
27 | __PACKAGE__->meta->add_attribute('lazy' => (reader => 'is_lazy' )); |
26fbace8 |
28 | __PACKAGE__->meta->add_attribute('lazy_build' => (reader => 'is_lazy_build' )); |
1a563243 |
29 | __PACKAGE__->meta->add_attribute('coerce' => (reader => 'should_coerce' )); |
30 | __PACKAGE__->meta->add_attribute('weak_ref' => (reader => 'is_weak_ref' )); |
31 | __PACKAGE__->meta->add_attribute('auto_deref' => (reader => 'should_auto_deref')); |
82168dbb |
32 | __PACKAGE__->meta->add_attribute('type_constraint' => ( |
33 | reader => 'type_constraint', |
34 | predicate => 'has_type_constraint', |
35 | )); |
8c9d74e7 |
36 | __PACKAGE__->meta->add_attribute('trigger' => ( |
37 | reader => 'trigger', |
38 | predicate => 'has_trigger', |
39 | )); |
452bac1b |
40 | __PACKAGE__->meta->add_attribute('handles' => ( |
41 | reader => 'handles', |
42 | predicate => 'has_handles', |
43 | )); |
ddbdc0cb |
44 | __PACKAGE__->meta->add_attribute('documentation' => ( |
45 | reader => 'documentation', |
46 | predicate => 'has_documentation', |
47 | )); |
82168dbb |
48 | |
78cd1d3b |
49 | sub new { |
26fbace8 |
50 | my ($class, $name, %options) = @_; |
51 | $class->_process_options($name, \%options); |
52 | return $class->SUPER::new($name, %options); |
1d768fb1 |
53 | } |
54 | |
ce0e8d63 |
55 | sub clone_and_inherit_options { |
56 | my ($self, %options) = @_; |
83cc9094 |
57 | # you can change default, required, coerce, documentation and lazy |
ce0e8d63 |
58 | my %actual_options; |
83cc9094 |
59 | foreach my $legal_option (qw(default coerce required documentation lazy)) { |
ce0e8d63 |
60 | if (exists $options{$legal_option}) { |
61 | $actual_options{$legal_option} = $options{$legal_option}; |
62 | delete $options{$legal_option}; |
63 | } |
64 | } |
26fbace8 |
65 | |
83cc9094 |
66 | # handles can only be added, not changed |
67 | if ($options{handles}) { |
68 | confess "You can only add the 'handles' option, you cannot change it" |
69 | if $self->has_handles; |
70 | $actual_options{handles} = $options{handles}; |
71 | delete $options{handles}; |
72 | } |
26fbace8 |
73 | |
74 | # isa can be changed, but only if the |
75 | # new type is a subtype |
ce0e8d63 |
76 | if ($options{isa}) { |
77 | my $type_constraint; |
26fbace8 |
78 | if (blessed($options{isa}) && $options{isa}->isa('Moose::Meta::TypeConstraint')) { |
79 | $type_constraint = $options{isa}; |
80 | } |
81 | else { |
82 | $type_constraint = Moose::Util::TypeConstraints::find_type_constraint($options{isa}); |
83 | (defined $type_constraint) |
84 | || confess "Could not find the type constraint '" . $options{isa} . "'"; |
85 | } |
86 | # NOTE: |
87 | # check here to see if the new type |
88 | # is a subtype of the old one |
89 | ($type_constraint->is_subtype_of($self->type_constraint->name)) |
90 | || confess "New type constraint setting must be a subtype of inherited one" |
91 | # iff we have a type constraint that is ... |
92 | if $self->has_type_constraint; |
93 | # then we use it :) |
94 | $actual_options{type_constraint} = $type_constraint; |
ce0e8d63 |
95 | delete $options{isa}; |
96 | } |
26fbace8 |
97 | (scalar keys %options == 0) |
ce0e8d63 |
98 | || confess "Illegal inherited options => (" . (join ', ' => keys %options) . ")"; |
99 | $self->clone(%actual_options); |
1d768fb1 |
100 | } |
101 | |
102 | sub _process_options { |
103 | my ($class, $name, $options) = @_; |
26fbace8 |
104 | |
105 | if (exists $options->{is}) { |
106 | if ($options->{is} eq 'ro') { |
107 | $options->{reader} ||= $name; |
108 | (!exists $options->{trigger}) |
109 | || confess "Cannot have a trigger on a read-only attribute"; |
110 | } |
111 | elsif ($options->{is} eq 'rw') { |
112 | $options->{accessor} = $name; |
113 | ((reftype($options->{trigger}) || '') eq 'CODE') |
114 | || confess "Trigger must be a CODE ref" |
115 | if exists $options->{trigger}; |
116 | } |
117 | else { |
118 | confess "I do not understand this option (is => " . $options->{is} . ")" |
119 | } |
120 | } |
121 | |
122 | if (exists $options->{isa}) { |
123 | |
124 | if (exists $options->{does}) { |
125 | if (eval { $options->{isa}->can('does') }) { |
126 | ($options->{isa}->does($options->{does})) |
127 | || confess "Cannot have an isa option and a does option if the isa does not do the does"; |
128 | } |
129 | else { |
130 | confess "Cannot have an isa option which cannot ->does()"; |
131 | } |
132 | } |
133 | |
134 | # allow for anon-subtypes here ... |
135 | if (blessed($options->{isa}) && $options->{isa}->isa('Moose::Meta::TypeConstraint')) { |
136 | $options->{type_constraint} = $options->{isa}; |
137 | } |
138 | else { |
139 | $options->{type_constraint} = Moose::Util::TypeConstraints::find_or_create_type_constraint( |
140 | $options->{isa} => { |
141 | parent => Moose::Util::TypeConstraints::find_type_constraint('Object'), |
142 | constraint => sub { $_[0]->isa($options->{isa}) } |
143 | } |
144 | ); |
145 | } |
146 | } |
147 | elsif (exists $options->{does}) { |
148 | # allow for anon-subtypes here ... |
149 | if (blessed($options->{does}) && $options->{does}->isa('Moose::Meta::TypeConstraint')) { |
150 | $options->{type_constraint} = $options->{isa}; |
151 | } |
152 | else { |
153 | $options->{type_constraint} = Moose::Util::TypeConstraints::find_or_create_type_constraint( |
154 | $options->{does} => { |
155 | parent => Moose::Util::TypeConstraints::find_type_constraint('Role'), |
156 | constraint => sub { $_[0]->does($options->{does}) } |
157 | } |
158 | ); |
159 | } |
160 | } |
161 | |
162 | if (exists $options->{coerce} && $options->{coerce}) { |
163 | (exists $options->{type_constraint}) |
164 | || confess "You cannot have coercion without specifying a type constraint"; |
4b598ea3 |
165 | confess "You cannot have a weak reference to a coerced value" |
26fbace8 |
166 | if $options->{weak_ref}; |
167 | } |
168 | |
169 | if (exists $options->{auto_deref} && $options->{auto_deref}) { |
170 | (exists $options->{type_constraint}) |
171 | || confess "You cannot auto-dereference without specifying a type constraint"; |
172 | ($options->{type_constraint}->is_a_type_of('ArrayRef') || |
94b8bbb8 |
173 | $options->{type_constraint}->is_a_type_of('HashRef')) |
26fbace8 |
174 | || confess "You cannot auto-dereference anything other than a ArrayRef or HashRef"; |
175 | } |
176 | |
177 | if (exists $options->{lazy_build} && $options->{lazy_build} == 1) { |
178 | confess("You can not use lazy_build and default for the same attribute") |
179 | if exists $options->{default}; |
180 | $options->{lazy} = 1; |
181 | $options->{required} = 1; |
58f85113 |
182 | $options->{builder} ||= "_build_${name}"; |
26fbace8 |
183 | if($name =~ /^_/){ |
26fbace8 |
184 | $options->{clearer} ||= "_clear${name}"; |
185 | $options->{predicate} ||= "_has${name}"; |
186 | } else { |
26fbace8 |
187 | $options->{clearer} ||= "clear_${name}"; |
188 | $options->{predicate} ||= "has_${name}"; |
189 | } |
190 | } |
191 | |
192 | if (exists $options->{lazy} && $options->{lazy}) { |
193 | (exists $options->{default} || exists $options->{builder} ) |
194 | || confess "You cannot have lazy attribute without specifying a default value for it"; |
195 | } |
196 | |
78cd1d3b |
197 | } |
c0e30cf5 |
198 | |
d500266f |
199 | sub initialize_instance_slot { |
ddd0ec20 |
200 | my ($self, $meta_instance, $instance, $params) = @_; |
d500266f |
201 | my $init_arg = $self->init_arg(); |
202 | # try to fetch the init arg from the %params ... |
ddd0ec20 |
203 | |
26fbace8 |
204 | my $val; |
1ed0b94f |
205 | my $value_is_set; |
d500266f |
206 | if (exists $params->{$init_arg}) { |
207 | $val = $params->{$init_arg}; |
1ed0b94f |
208 | $value_is_set = 1; |
d500266f |
209 | } |
210 | else { |
211 | # skip it if it's lazy |
212 | return if $self->is_lazy; |
213 | # and die if it's required and doesn't have a default value |
26fbace8 |
214 | confess "Attribute (" . $self->name . ") is required" |
215 | if $self->is_required && !$self->has_default && !$self->has_builder; |
ddd0ec20 |
216 | |
1ed0b94f |
217 | # if nothing was in the %params, we can use the |
218 | # attribute's default value (if it has one) |
219 | if ($self->has_default) { |
220 | $val = $self->default($instance); |
221 | $value_is_set = 1; |
222 | } elsif ($self->has_builder) { |
0b26305c |
223 | if(my $builder = $instance->can($self->builder)){ |
1ed0b94f |
224 | $val = $instance->$builder; |
225 | $value_is_set = 1; |
226 | } else { |
0b26305c |
227 | confess(blessed($instance)." does not support builder method '".$self->builder."' for attribute '" . $self->name . "'"); |
1ed0b94f |
228 | } |
a0748c37 |
229 | } |
26fbace8 |
230 | } |
231 | |
1ed0b94f |
232 | return unless $value_is_set; |
233 | |
234 | if ($self->has_type_constraint) { |
235 | my $type_constraint = $self->type_constraint; |
236 | if ($self->should_coerce && $type_constraint->has_coercion) { |
237 | $val = $type_constraint->coerce($val); |
d500266f |
238 | } |
1ed0b94f |
239 | (defined($type_constraint->check($val))) |
240 | || confess "Attribute (" . |
241 | $self->name . |
242 | ") does not pass the type constraint (" . |
243 | $type_constraint->name . |
244 | ") with '" . |
245 | (defined $val |
246 | ? (blessed($val) && overload::Overloaded($val) |
247 | ? overload::StrVal($val) |
248 | : $val) |
249 | : 'undef') . |
250 | "'"; |
251 | } |
ddd0ec20 |
252 | |
ac1ef2f9 |
253 | $meta_instance->set_slot_value($instance, $self->name, $val); |
26fbace8 |
254 | $meta_instance->weaken_slot_value($instance, $self->name) |
1ed0b94f |
255 | if ref $val && $self->is_weak_ref; |
d500266f |
256 | } |
257 | |
d617b644 |
258 | ## Slot management |
9e93dd19 |
259 | |
946289d1 |
260 | sub set_value { |
261 | my ($self, $instance, $value) = @_; |
26fbace8 |
262 | |
946289d1 |
263 | my $attr_name = $self->name; |
26fbace8 |
264 | |
946289d1 |
265 | if ($self->is_required) { |
26fbace8 |
266 | defined($value) |
946289d1 |
267 | || confess "Attribute ($attr_name) is required, so cannot be set to undef"; |
268 | } |
26fbace8 |
269 | |
946289d1 |
270 | if ($self->has_type_constraint) { |
26fbace8 |
271 | |
946289d1 |
272 | my $type_constraint = $self->type_constraint; |
26fbace8 |
273 | |
946289d1 |
274 | if ($self->should_coerce) { |
26fbace8 |
275 | $value = $type_constraint->coerce($value); |
946289d1 |
276 | } |
277 | defined($type_constraint->_compiled_type_constraint->($value)) |
26fbace8 |
278 | || confess "Attribute ($attr_name) does not pass the type constraint (" |
279 | . $type_constraint->name |
280 | . ") with " |
281 | . (defined($value) |
282 | ? ("'" . |
283 | (blessed($value) && overload::Overloaded($value) |
284 | ? overload::StrVal($value) |
285 | : $value) |
286 | . "'") |
a909a4df |
287 | : "undef") |
946289d1 |
288 | if defined($value); |
289 | } |
26fbace8 |
290 | |
946289d1 |
291 | my $meta_instance = Class::MOP::Class->initialize(blessed($instance)) |
292 | ->get_meta_instance; |
26fbace8 |
293 | |
294 | $meta_instance->set_slot_value($instance, $attr_name, $value); |
295 | |
946289d1 |
296 | if (ref $value && $self->is_weak_ref) { |
26fbace8 |
297 | $meta_instance->weaken_slot_value($instance, $attr_name); |
946289d1 |
298 | } |
26fbace8 |
299 | |
946289d1 |
300 | if ($self->has_trigger) { |
301 | $self->trigger->($instance, $value, $self); |
302 | } |
303 | } |
304 | |
305 | sub get_value { |
306 | my ($self, $instance) = @_; |
26fbace8 |
307 | |
946289d1 |
308 | if ($self->is_lazy) { |
26fbace8 |
309 | unless ($self->has_value($instance)) { |
310 | if ($self->has_default) { |
311 | my $default = $self->default($instance); |
312 | $self->set_value($instance, $default); |
313 | } |
314 | if ( $self->has_builder ){ |
0b26305c |
315 | if(my $builder = $instance->can($self->builder)){ |
a0748c37 |
316 | $self->set_value($instance, $instance->$builder); |
317 | } else { |
0b26305c |
318 | confess(blessed($instance)." does not support builder method '".$self->builder."' for attribute '" . $self->name . "'"); |
a0748c37 |
319 | } |
26fbace8 |
320 | } else { |
321 | $self->set_value($instance, undef); |
322 | } |
323 | } |
946289d1 |
324 | } |
26fbace8 |
325 | |
946289d1 |
326 | if ($self->should_auto_deref) { |
26fbace8 |
327 | |
946289d1 |
328 | my $type_constraint = $self->type_constraint; |
329 | |
330 | if ($type_constraint->is_a_type_of('ArrayRef')) { |
331 | my $rv = $self->SUPER::get_value($instance); |
332 | return unless defined $rv; |
333 | return wantarray ? @{ $rv } : $rv; |
26fbace8 |
334 | } |
946289d1 |
335 | elsif ($type_constraint->is_a_type_of('HashRef')) { |
336 | my $rv = $self->SUPER::get_value($instance); |
337 | return unless defined $rv; |
338 | return wantarray ? %{ $rv } : $rv; |
26fbace8 |
339 | } |
946289d1 |
340 | else { |
341 | confess "Can not auto de-reference the type constraint '" . $type_constraint->name . "'"; |
342 | } |
26fbace8 |
343 | |
946289d1 |
344 | } |
345 | else { |
26fbace8 |
346 | |
946289d1 |
347 | return $self->SUPER::get_value($instance); |
26fbace8 |
348 | } |
946289d1 |
349 | } |
a15dff8d |
350 | |
26fbace8 |
351 | ## installing accessors |
c0e30cf5 |
352 | |
d617b644 |
353 | sub accessor_metaclass { 'Moose::Meta::Method::Accessor' } |
d7f17ebb |
354 | |
452bac1b |
355 | sub install_accessors { |
356 | my $self = shift; |
26fbace8 |
357 | $self->SUPER::install_accessors(@_); |
358 | |
452bac1b |
359 | if ($self->has_handles) { |
26fbace8 |
360 | |
452bac1b |
361 | # NOTE: |
362 | # Here we canonicalize the 'handles' option |
26fbace8 |
363 | # this will sort out any details and always |
364 | # return an hash of methods which we want |
452bac1b |
365 | # to delagate to, see that method for details |
366 | my %handles = $self->_canonicalize_handles(); |
26fbace8 |
367 | |
452bac1b |
368 | # find the name of the accessor for this attribute |
369 | my $accessor_name = $self->reader || $self->accessor; |
370 | (defined $accessor_name) |
371 | || confess "You cannot install delegation without a reader or accessor for the attribute"; |
26fbace8 |
372 | |
452bac1b |
373 | # make sure we handle HASH accessors correctly |
374 | ($accessor_name) = keys %{$accessor_name} |
375 | if ref($accessor_name) eq 'HASH'; |
26fbace8 |
376 | |
452bac1b |
377 | # install the delegation ... |
378 | my $associated_class = $self->associated_class; |
379 | foreach my $handle (keys %handles) { |
380 | my $method_to_call = $handles{$handle}; |
26fbace8 |
381 | |
452bac1b |
382 | (!$associated_class->has_method($handle)) |
383 | || confess "You cannot overwrite a locally defined method ($handle) with a delegation"; |
26fbace8 |
384 | |
d022f632 |
385 | # NOTE: |
386 | # handles is not allowed to delegate |
26fbace8 |
387 | # any of these methods, as they will |
388 | # override the ones in your class, which |
d022f632 |
389 | # is almost certainly not what you want. |
390 | next if $handle =~ /^BUILD|DEMOLISH$/ || Moose::Object->can($handle); |
26fbace8 |
391 | |
452bac1b |
392 | if ((reftype($method_to_call) || '') eq 'CODE') { |
26fbace8 |
393 | $associated_class->add_method($handle => $method_to_call); |
452bac1b |
394 | } |
395 | else { |
396 | $associated_class->add_method($handle => sub { |
b805c70c |
397 | # FIXME |
26fbace8 |
398 | # we should check for lack of |
399 | # a callable return value from |
400 | # the accessor here |
cbe25729 |
401 | my $proxy = (shift)->$accessor_name(); |
402 | @_ = ($proxy, @_); |
403 | goto &{ $proxy->can($method_to_call)}; |
452bac1b |
404 | }); |
405 | } |
406 | } |
407 | } |
26fbace8 |
408 | |
452bac1b |
409 | return; |
410 | } |
411 | |
98aae381 |
412 | # private methods to help delegation ... |
413 | |
452bac1b |
414 | sub _canonicalize_handles { |
415 | my $self = shift; |
416 | my $handles = $self->handles; |
c84f324f |
417 | if (my $handle_type = ref($handles)) { |
418 | if ($handle_type eq 'HASH') { |
419 | return %{$handles}; |
420 | } |
421 | elsif ($handle_type eq 'ARRAY') { |
422 | return map { $_ => $_ } @{$handles}; |
423 | } |
424 | elsif ($handle_type eq 'Regexp') { |
425 | ($self->has_type_constraint) |
426 | || confess "Cannot delegate methods based on a RegExpr without a type constraint (isa)"; |
26fbace8 |
427 | return map { ($_ => $_) } |
c84f324f |
428 | grep { /$handles/ } $self->_get_delegate_method_list; |
429 | } |
430 | elsif ($handle_type eq 'CODE') { |
431 | return $handles->($self, $self->_find_delegate_metaclass); |
432 | } |
433 | else { |
434 | confess "Unable to canonicalize the 'handles' option with $handles"; |
435 | } |
452bac1b |
436 | } |
437 | else { |
c84f324f |
438 | my $role_meta = eval { $handles->meta }; |
439 | if ($@) { |
26fbace8 |
440 | confess "Unable to canonicalize the 'handles' option with $handles because : $@"; |
c84f324f |
441 | } |
442 | |
443 | (blessed $role_meta && $role_meta->isa('Moose::Meta::Role')) |
444 | || confess "Unable to canonicalize the 'handles' option with $handles because ->meta is not a Moose::Meta::Role"; |
26fbace8 |
445 | |
c84f324f |
446 | return map { $_ => $_ } ( |
26fbace8 |
447 | $role_meta->get_method_list, |
c84f324f |
448 | $role_meta->get_required_method_list |
449 | ); |
452bac1b |
450 | } |
451 | } |
452 | |
453 | sub _find_delegate_metaclass { |
454 | my $self = shift; |
98aae381 |
455 | if (my $class = $self->_isa_metadata) { |
26fbace8 |
456 | # if the class does have |
452bac1b |
457 | # a meta method, use it |
458 | return $class->meta if $class->can('meta'); |
26fbace8 |
459 | # otherwise we might be |
452bac1b |
460 | # dealing with a non-Moose |
26fbace8 |
461 | # class, and need to make |
452bac1b |
462 | # our own metaclass |
463 | return Moose::Meta::Class->initialize($class); |
464 | } |
98aae381 |
465 | elsif (my $role = $self->_does_metadata) { |
26fbace8 |
466 | # our role will always have |
452bac1b |
467 | # a meta method |
98aae381 |
468 | return $role->meta; |
452bac1b |
469 | } |
470 | else { |
471 | confess "Cannot find delegate metaclass for attribute " . $self->name; |
472 | } |
473 | } |
474 | |
475 | sub _get_delegate_method_list { |
476 | my $self = shift; |
477 | my $meta = $self->_find_delegate_metaclass; |
478 | if ($meta->isa('Class::MOP::Class')) { |
093b12c2 |
479 | return map { $_->{name} } # NOTE: !never! delegate &meta |
26fbace8 |
480 | grep { $_->{class} ne 'Moose::Object' && $_->{name} ne 'meta' } |
452bac1b |
481 | $meta->compute_all_applicable_methods; |
482 | } |
483 | elsif ($meta->isa('Moose::Meta::Role')) { |
26fbace8 |
484 | return $meta->get_method_list; |
452bac1b |
485 | } |
486 | else { |
487 | confess "Unable to recognize the delegate metaclass '$meta'"; |
488 | } |
489 | } |
490 | |
c0e30cf5 |
491 | 1; |
492 | |
493 | __END__ |
494 | |
495 | =pod |
496 | |
497 | =head1 NAME |
498 | |
6ba6d68c |
499 | Moose::Meta::Attribute - The Moose attribute metaclass |
c0e30cf5 |
500 | |
501 | =head1 DESCRIPTION |
502 | |
26fbace8 |
503 | This is a subclass of L<Class::MOP::Attribute> with Moose specific |
504 | extensions. |
6ba6d68c |
505 | |
26fbace8 |
506 | For the most part, the only time you will ever encounter an |
507 | instance of this class is if you are doing some serious deep |
508 | introspection. To really understand this class, you need to refer |
6ba6d68c |
509 | to the L<Class::MOP::Attribute> documentation. |
e522431d |
510 | |
c0e30cf5 |
511 | =head1 METHODS |
512 | |
6ba6d68c |
513 | =head2 Overridden methods |
514 | |
26fbace8 |
515 | These methods override methods in L<Class::MOP::Attribute> and add |
516 | Moose specific features. You can safely assume though that they |
6ba6d68c |
517 | will behave just as L<Class::MOP::Attribute> does. |
518 | |
c0e30cf5 |
519 | =over 4 |
520 | |
521 | =item B<new> |
522 | |
d500266f |
523 | =item B<initialize_instance_slot> |
524 | |
452bac1b |
525 | =item B<install_accessors> |
526 | |
39b3bc94 |
527 | =item B<accessor_metaclass> |
528 | |
946289d1 |
529 | =item B<get_value> |
530 | |
531 | =item B<set_value> |
532 | |
bcbaa845 |
533 | eval { $point->meta->get_attribute('x')->set_value($point, 'fourty-two') }; |
534 | if($@) { |
535 | print "Oops: $@\n"; |
536 | } |
537 | |
538 | I<Attribute (x) does not pass the type constraint (Int) with 'fourty-two'> |
539 | |
540 | Before setting the value, a check is made on the type constraint of |
541 | the attribute, if it has one, to see if the value passes it. If the |
542 | value fails to pass, the set operation dies with a L<Carp/confess>. |
543 | |
544 | Any coercion to convert values is done before checking the type constraint. |
545 | |
546 | To check a value against a type constraint before setting it, fetch the |
547 | attribute instance using L<Moose::Meta::Attribute/find_attribute_by_name>, |
548 | fetch the type_constraint from the attribute using L<Moose::Meta::Attribute/type_constraint> |
549 | and call L<Moose::Meta::TypeConstraint/check>. See L<Moose::Cookbook::RecipeX> |
550 | for an example. |
551 | |
a15dff8d |
552 | =back |
553 | |
6ba6d68c |
554 | =head2 Additional Moose features |
555 | |
26fbace8 |
556 | Moose attributes support type-constraint checking, weak reference |
557 | creation and type coercion. |
6ba6d68c |
558 | |
a15dff8d |
559 | =over 4 |
560 | |
9e93dd19 |
561 | =item B<clone_and_inherit_options> |
562 | |
26fbace8 |
563 | This is to support the C<has '+foo'> feature, it clones an attribute |
564 | from a superclass and allows a very specific set of changes to be made |
9e93dd19 |
565 | to the attribute. |
566 | |
a15dff8d |
567 | =item B<has_type_constraint> |
568 | |
6ba6d68c |
569 | Returns true if this meta-attribute has a type constraint. |
570 | |
a15dff8d |
571 | =item B<type_constraint> |
572 | |
26fbace8 |
573 | A read-only accessor for this meta-attribute's type constraint. For |
574 | more information on what you can do with this, see the documentation |
6ba6d68c |
575 | for L<Moose::Meta::TypeConstraint>. |
a15dff8d |
576 | |
452bac1b |
577 | =item B<has_handles> |
578 | |
579 | Returns true if this meta-attribute performs delegation. |
580 | |
581 | =item B<handles> |
582 | |
583 | This returns the value which was passed into the handles option. |
584 | |
6ba6d68c |
585 | =item B<is_weak_ref> |
a15dff8d |
586 | |
02a0fb52 |
587 | Returns true if this meta-attribute produces a weak reference. |
4b598ea3 |
588 | |
ca01a97b |
589 | =item B<is_required> |
590 | |
02a0fb52 |
591 | Returns true if this meta-attribute is required to have a value. |
ca01a97b |
592 | |
593 | =item B<is_lazy> |
594 | |
02a0fb52 |
595 | Returns true if this meta-attribute should be initialized lazily. |
ca01a97b |
596 | |
26fbace8 |
597 | NOTE: lazy attributes, B<must> have a C<default> or C<builder> field set. |
598 | |
599 | =item B<is_lazy_build> |
600 | |
601 | Returns true if this meta-attribute should be initialized lazily through |
602 | the builder generated by lazy_build. Using C<lazy_build =E<gt> 1> will |
603 | make your attribute required and lazy. In addition it will set the builder, clearer |
604 | and predicate options for you using the following convention. |
605 | |
606 | #If your attribute name starts with an underscore: |
607 | has '_foo' => (lazy_build => 1); |
608 | #is the same as |
58f85113 |
609 | has '_foo' => (lazy => 1, required => 1, predicate => '_has_foo', clearer => '_clear_foo', builder => '_build__foo); |
26fbace8 |
610 | # or |
58f85113 |
611 | has '_foo' => (lazy => 1, required => 1, predicate => '_has_foo', clearer => '_clear_foo', default => sub{shift->_build__foo}); |
26fbace8 |
612 | |
613 | #If your attribute name does not start with an underscore: |
58f85113 |
614 | has 'foo' => (lazy_build => 1); |
615 | #is the same as |
616 | has 'foo' => (lazy => 1, required => 1, predicate => 'has_foo', clearer => 'clear_foo', builder => '_build_foo); |
26fbace8 |
617 | # or |
58f85113 |
618 | has 'foo' => (lazy => 1, required => 1, predicate => 'has_foo', clearer => 'clear_foo', default => sub{shift->_build_foo}); |
619 | |
620 | The reason for the different naming of the C<builder> is that the C<builder> |
621 | method is a private method while the C<clearer> and C<predicate> methods |
622 | are public methods. |
26fbace8 |
623 | |
624 | NOTE: This means your class should provide a method whose name matches the value |
58f85113 |
625 | of the builder part, in this case _build__foo or _build_foo. |
ca01a97b |
626 | |
34a66aa3 |
627 | =item B<should_coerce> |
4b598ea3 |
628 | |
02a0fb52 |
629 | Returns true if this meta-attribute should perform type coercion. |
6ba6d68c |
630 | |
536f0b17 |
631 | =item B<should_auto_deref> |
632 | |
26fbace8 |
633 | Returns true if this meta-attribute should perform automatic |
634 | auto-dereferencing. |
536f0b17 |
635 | |
26fbace8 |
636 | NOTE: This can only be done for attributes whose type constraint is |
536f0b17 |
637 | either I<ArrayRef> or I<HashRef>. |
638 | |
8c9d74e7 |
639 | =item B<has_trigger> |
640 | |
02a0fb52 |
641 | Returns true if this meta-attribute has a trigger set. |
642 | |
8c9d74e7 |
643 | =item B<trigger> |
644 | |
26fbace8 |
645 | This is a CODE reference which will be executed every time the |
646 | value of an attribute is assigned. The CODE ref will get two values, |
647 | the invocant and the new value. This can be used to handle I<basic> |
02a0fb52 |
648 | bi-directional relations. |
649 | |
ddbdc0cb |
650 | =item B<documentation> |
651 | |
26fbace8 |
652 | This is a string which contains the documentation for this attribute. |
ddbdc0cb |
653 | It serves no direct purpose right now, but it might in the future |
654 | in some kind of automated documentation system perhaps. |
655 | |
656 | =item B<has_documentation> |
657 | |
658 | Returns true if this meta-attribute has any documentation. |
659 | |
c0e30cf5 |
660 | =back |
661 | |
662 | =head1 BUGS |
663 | |
26fbace8 |
664 | All complex software has bugs lurking in it, and this module is no |
c0e30cf5 |
665 | exception. If you find a bug please either email me, or add the bug |
666 | to cpan-RT. |
667 | |
c0e30cf5 |
668 | =head1 AUTHOR |
669 | |
670 | Stevan Little E<lt>stevan@iinteractive.comE<gt> |
671 | |
98aae381 |
672 | Yuval Kogman E<lt>nothingmuch@woobling.comE<gt> |
673 | |
c0e30cf5 |
674 | =head1 COPYRIGHT AND LICENSE |
675 | |
b77fdbed |
676 | Copyright 2006, 2007 by Infinity Interactive, Inc. |
c0e30cf5 |
677 | |
678 | L<http://www.iinteractive.com> |
679 | |
680 | This library is free software; you can redistribute it and/or modify |
26fbace8 |
681 | it under the same terms as Perl itself. |
c0e30cf5 |
682 | |
8a7a9c53 |
683 | =cut |