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 | |
f3c4e20e |
11 | our $VERSION = '0.15'; |
d44714be |
12 | our $AUTHORITY = 'cpan:STEVAN'; |
78cd1d3b |
13 | |
8ee73eeb |
14 | use Moose::Meta::Method::Accessor; |
a3c7e2fe |
15 | use Moose::Util::TypeConstraints (); |
bc1e29b5 |
16 | |
c0e30cf5 |
17 | use base 'Class::MOP::Attribute'; |
18 | |
452bac1b |
19 | # options which are not directly used |
20 | # but we store them for metadata purposes |
98aae381 |
21 | __PACKAGE__->meta->add_attribute('isa' => (reader => '_isa_metadata')); |
22 | __PACKAGE__->meta->add_attribute('does' => (reader => '_does_metadata')); |
23 | __PACKAGE__->meta->add_attribute('is' => (reader => '_is_metadata')); |
452bac1b |
24 | |
25 | # these are actual options for the attrs |
1a563243 |
26 | __PACKAGE__->meta->add_attribute('required' => (reader => 'is_required' )); |
27 | __PACKAGE__->meta->add_attribute('lazy' => (reader => 'is_lazy' )); |
26fbace8 |
28 | __PACKAGE__->meta->add_attribute('lazy_build' => (reader => 'is_lazy_build' )); |
1a563243 |
29 | __PACKAGE__->meta->add_attribute('coerce' => (reader => 'should_coerce' )); |
30 | __PACKAGE__->meta->add_attribute('weak_ref' => (reader => 'is_weak_ref' )); |
31 | __PACKAGE__->meta->add_attribute('auto_deref' => (reader => 'should_auto_deref')); |
82168dbb |
32 | __PACKAGE__->meta->add_attribute('type_constraint' => ( |
33 | reader => 'type_constraint', |
34 | predicate => 'has_type_constraint', |
35 | )); |
8c9d74e7 |
36 | __PACKAGE__->meta->add_attribute('trigger' => ( |
37 | reader => 'trigger', |
38 | predicate => 'has_trigger', |
39 | )); |
452bac1b |
40 | __PACKAGE__->meta->add_attribute('handles' => ( |
41 | reader => 'handles', |
42 | predicate => 'has_handles', |
43 | )); |
ddbdc0cb |
44 | __PACKAGE__->meta->add_attribute('documentation' => ( |
45 | reader => 'documentation', |
46 | predicate => 'has_documentation', |
47 | )); |
82168dbb |
48 | |
78cd1d3b |
49 | sub new { |
f3c4e20e |
50 | my ($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 { |
f3c4e20e |
82 | $type_constraint = Moose::Util::TypeConstraints::find_or_create_type_constraint( |
83 | $options{isa} |
84 | ); |
26fbace8 |
85 | (defined $type_constraint) |
86 | || confess "Could not find the type constraint '" . $options{isa} . "'"; |
87 | } |
88 | # NOTE: |
89 | # check here to see if the new type |
90 | # is a subtype of the old one |
91 | ($type_constraint->is_subtype_of($self->type_constraint->name)) |
92 | || confess "New type constraint setting must be a subtype of inherited one" |
93 | # iff we have a type constraint that is ... |
94 | if $self->has_type_constraint; |
95 | # then we use it :) |
96 | $actual_options{type_constraint} = $type_constraint; |
ce0e8d63 |
97 | delete $options{isa}; |
98 | } |
26fbace8 |
99 | (scalar keys %options == 0) |
ce0e8d63 |
100 | || confess "Illegal inherited options => (" . (join ', ' => keys %options) . ")"; |
101 | $self->clone(%actual_options); |
1d768fb1 |
102 | } |
103 | |
104 | sub _process_options { |
105 | my ($class, $name, $options) = @_; |
f3c4e20e |
106 | |
107 | if (exists $options->{is}) { |
108 | if ($options->{is} eq 'ro') { |
109 | $options->{reader} ||= $name; |
110 | (!exists $options->{trigger}) |
111 | || confess "Cannot have a trigger on a read-only attribute"; |
112 | } |
113 | elsif ($options->{is} eq 'rw') { |
114 | $options->{accessor} = $name; |
115 | ((reftype($options->{trigger}) || '') eq 'CODE') |
116 | || confess "Trigger must be a CODE ref" |
117 | if exists $options->{trigger}; |
118 | } |
119 | else { |
120 | confess "I do not understand this option (is => " . $options->{is} . ")" |
121 | } |
122 | } |
123 | |
124 | if (exists $options->{isa}) { |
125 | |
126 | if (exists $options->{does}) { |
127 | if (eval { $options->{isa}->can('does') }) { |
128 | ($options->{isa}->does($options->{does})) |
129 | || confess "Cannot have an isa option and a does option if the isa does not do the does"; |
130 | } |
131 | else { |
132 | confess "Cannot have an isa option which cannot ->does()"; |
26fbace8 |
133 | } |
26fbace8 |
134 | } |
f3c4e20e |
135 | |
136 | # allow for anon-subtypes here ... |
137 | if (blessed($options->{isa}) && $options->{isa}->isa('Moose::Meta::TypeConstraint')) { |
138 | $options->{type_constraint} = $options->{isa}; |
139 | } |
140 | else { |
141 | $options->{type_constraint} = Moose::Util::TypeConstraints::find_or_create_type_constraint( |
142 | $options->{isa} => { |
143 | parent => Moose::Util::TypeConstraints::find_type_constraint('Object'), |
144 | constraint => sub { $_[0]->isa($options->{isa}) } |
26fbace8 |
145 | } |
f3c4e20e |
146 | ); |
147 | } |
148 | } |
149 | elsif (exists $options->{does}) { |
150 | # allow for anon-subtypes here ... |
151 | if (blessed($options->{does}) && $options->{does}->isa('Moose::Meta::TypeConstraint')) { |
152 | $options->{type_constraint} = $options->{isa}; |
153 | } |
154 | else { |
155 | $options->{type_constraint} = Moose::Util::TypeConstraints::find_or_create_type_constraint( |
156 | $options->{does} => { |
157 | parent => Moose::Util::TypeConstraints::find_type_constraint('Role'), |
158 | constraint => sub { $_[0]->does($options->{does}) } |
26fbace8 |
159 | } |
f3c4e20e |
160 | ); |
26fbace8 |
161 | } |
f3c4e20e |
162 | } |
163 | |
164 | if (exists $options->{coerce} && $options->{coerce}) { |
165 | (exists $options->{type_constraint}) |
166 | || confess "You cannot have coercion without specifying a type constraint"; |
167 | confess "You cannot have a weak reference to a coerced value" |
168 | if $options->{weak_ref}; |
169 | } |
170 | |
171 | if (exists $options->{auto_deref} && $options->{auto_deref}) { |
172 | (exists $options->{type_constraint}) |
173 | || confess "You cannot auto-dereference without specifying a type constraint"; |
174 | ($options->{type_constraint}->is_a_type_of('ArrayRef') || |
175 | $options->{type_constraint}->is_a_type_of('HashRef')) |
176 | || confess "You cannot auto-dereference anything other than a ArrayRef or HashRef"; |
177 | } |
178 | |
179 | if (exists $options->{lazy_build} && $options->{lazy_build} == 1) { |
180 | confess("You can not use lazy_build and default for the same attribute") |
181 | if exists $options->{default}; |
182 | $options->{lazy} = 1; |
183 | $options->{required} = 1; |
184 | $options->{builder} ||= "_build_${name}"; |
185 | if($name =~ /^_/){ |
186 | $options->{clearer} ||= "_clear${name}"; |
187 | $options->{predicate} ||= "_has${name}"; |
188 | } else { |
189 | $options->{clearer} ||= "clear_${name}"; |
190 | $options->{predicate} ||= "has_${name}"; |
26fbace8 |
191 | } |
f3c4e20e |
192 | } |
193 | |
194 | if (exists $options->{lazy} && $options->{lazy}) { |
195 | (exists $options->{default} || exists $options->{builder} ) |
196 | || confess "You cannot have lazy attribute without specifying a default value for it"; |
197 | } |
26fbace8 |
198 | |
78cd1d3b |
199 | } |
c0e30cf5 |
200 | |
d500266f |
201 | sub initialize_instance_slot { |
ddd0ec20 |
202 | my ($self, $meta_instance, $instance, $params) = @_; |
d500266f |
203 | my $init_arg = $self->init_arg(); |
204 | # try to fetch the init arg from the %params ... |
ddd0ec20 |
205 | |
26fbace8 |
206 | my $val; |
1ed0b94f |
207 | my $value_is_set; |
d500266f |
208 | if (exists $params->{$init_arg}) { |
209 | $val = $params->{$init_arg}; |
1ed0b94f |
210 | $value_is_set = 1; |
d500266f |
211 | } |
212 | else { |
213 | # skip it if it's lazy |
214 | return if $self->is_lazy; |
215 | # and die if it's required and doesn't have a default value |
26fbace8 |
216 | confess "Attribute (" . $self->name . ") is required" |
217 | if $self->is_required && !$self->has_default && !$self->has_builder; |
ddd0ec20 |
218 | |
1ed0b94f |
219 | # if nothing was in the %params, we can use the |
220 | # attribute's default value (if it has one) |
221 | if ($self->has_default) { |
222 | $val = $self->default($instance); |
223 | $value_is_set = 1; |
224 | } elsif ($self->has_builder) { |
0b26305c |
225 | if(my $builder = $instance->can($self->builder)){ |
1ed0b94f |
226 | $val = $instance->$builder; |
227 | $value_is_set = 1; |
228 | } else { |
0b26305c |
229 | confess(blessed($instance)." does not support builder method '".$self->builder."' for attribute '" . $self->name . "'"); |
1ed0b94f |
230 | } |
a0748c37 |
231 | } |
26fbace8 |
232 | } |
233 | |
1ed0b94f |
234 | return unless $value_is_set; |
235 | |
236 | if ($self->has_type_constraint) { |
237 | my $type_constraint = $self->type_constraint; |
238 | if ($self->should_coerce && $type_constraint->has_coercion) { |
239 | $val = $type_constraint->coerce($val); |
d500266f |
240 | } |
1ed0b94f |
241 | (defined($type_constraint->check($val))) |
242 | || confess "Attribute (" . |
243 | $self->name . |
244 | ") does not pass the type constraint (" . |
245 | $type_constraint->name . |
246 | ") with '" . |
247 | (defined $val |
248 | ? (blessed($val) && overload::Overloaded($val) |
249 | ? overload::StrVal($val) |
250 | : $val) |
251 | : 'undef') . |
252 | "'"; |
253 | } |
ddd0ec20 |
254 | |
ac1ef2f9 |
255 | $meta_instance->set_slot_value($instance, $self->name, $val); |
26fbace8 |
256 | $meta_instance->weaken_slot_value($instance, $self->name) |
1ed0b94f |
257 | if ref $val && $self->is_weak_ref; |
d500266f |
258 | } |
259 | |
d617b644 |
260 | ## Slot management |
9e93dd19 |
261 | |
946289d1 |
262 | sub set_value { |
263 | my ($self, $instance, $value) = @_; |
26fbace8 |
264 | |
946289d1 |
265 | my $attr_name = $self->name; |
26fbace8 |
266 | |
946289d1 |
267 | if ($self->is_required) { |
26fbace8 |
268 | defined($value) |
946289d1 |
269 | || confess "Attribute ($attr_name) is required, so cannot be set to undef"; |
270 | } |
26fbace8 |
271 | |
946289d1 |
272 | if ($self->has_type_constraint) { |
26fbace8 |
273 | |
946289d1 |
274 | my $type_constraint = $self->type_constraint; |
26fbace8 |
275 | |
946289d1 |
276 | if ($self->should_coerce) { |
26fbace8 |
277 | $value = $type_constraint->coerce($value); |
946289d1 |
278 | } |
279 | defined($type_constraint->_compiled_type_constraint->($value)) |
26fbace8 |
280 | || confess "Attribute ($attr_name) does not pass the type constraint (" |
281 | . $type_constraint->name |
282 | . ") with " |
283 | . (defined($value) |
284 | ? ("'" . |
285 | (blessed($value) && overload::Overloaded($value) |
286 | ? overload::StrVal($value) |
287 | : $value) |
288 | . "'") |
a909a4df |
289 | : "undef") |
946289d1 |
290 | if defined($value); |
291 | } |
26fbace8 |
292 | |
946289d1 |
293 | my $meta_instance = Class::MOP::Class->initialize(blessed($instance)) |
294 | ->get_meta_instance; |
26fbace8 |
295 | |
296 | $meta_instance->set_slot_value($instance, $attr_name, $value); |
297 | |
946289d1 |
298 | if (ref $value && $self->is_weak_ref) { |
26fbace8 |
299 | $meta_instance->weaken_slot_value($instance, $attr_name); |
946289d1 |
300 | } |
26fbace8 |
301 | |
946289d1 |
302 | if ($self->has_trigger) { |
303 | $self->trigger->($instance, $value, $self); |
304 | } |
305 | } |
306 | |
307 | sub get_value { |
308 | my ($self, $instance) = @_; |
26fbace8 |
309 | |
946289d1 |
310 | if ($self->is_lazy) { |
26fbace8 |
311 | unless ($self->has_value($instance)) { |
312 | if ($self->has_default) { |
313 | my $default = $self->default($instance); |
314 | $self->set_value($instance, $default); |
315 | } |
316 | if ( $self->has_builder ){ |
0b26305c |
317 | if(my $builder = $instance->can($self->builder)){ |
a0748c37 |
318 | $self->set_value($instance, $instance->$builder); |
319 | } else { |
0b26305c |
320 | confess(blessed($instance)." does not support builder method '".$self->builder."' for attribute '" . $self->name . "'"); |
a0748c37 |
321 | } |
26fbace8 |
322 | } else { |
323 | $self->set_value($instance, undef); |
324 | } |
325 | } |
946289d1 |
326 | } |
26fbace8 |
327 | |
946289d1 |
328 | if ($self->should_auto_deref) { |
26fbace8 |
329 | |
946289d1 |
330 | my $type_constraint = $self->type_constraint; |
331 | |
332 | if ($type_constraint->is_a_type_of('ArrayRef')) { |
333 | my $rv = $self->SUPER::get_value($instance); |
334 | return unless defined $rv; |
335 | return wantarray ? @{ $rv } : $rv; |
26fbace8 |
336 | } |
946289d1 |
337 | elsif ($type_constraint->is_a_type_of('HashRef')) { |
338 | my $rv = $self->SUPER::get_value($instance); |
339 | return unless defined $rv; |
340 | return wantarray ? %{ $rv } : $rv; |
26fbace8 |
341 | } |
946289d1 |
342 | else { |
343 | confess "Can not auto de-reference the type constraint '" . $type_constraint->name . "'"; |
344 | } |
26fbace8 |
345 | |
946289d1 |
346 | } |
347 | else { |
26fbace8 |
348 | |
946289d1 |
349 | return $self->SUPER::get_value($instance); |
26fbace8 |
350 | } |
946289d1 |
351 | } |
a15dff8d |
352 | |
26fbace8 |
353 | ## installing accessors |
c0e30cf5 |
354 | |
d617b644 |
355 | sub accessor_metaclass { 'Moose::Meta::Method::Accessor' } |
d7f17ebb |
356 | |
452bac1b |
357 | sub install_accessors { |
358 | my $self = shift; |
26fbace8 |
359 | $self->SUPER::install_accessors(@_); |
360 | |
452bac1b |
361 | if ($self->has_handles) { |
26fbace8 |
362 | |
452bac1b |
363 | # NOTE: |
364 | # Here we canonicalize the 'handles' option |
26fbace8 |
365 | # this will sort out any details and always |
366 | # return an hash of methods which we want |
452bac1b |
367 | # to delagate to, see that method for details |
368 | my %handles = $self->_canonicalize_handles(); |
26fbace8 |
369 | |
f3c4e20e |
370 | # find the accessor method for this attribute |
371 | my $accessor = $self->get_read_method_ref; |
372 | # then unpack it if we need too ... |
373 | $accessor = $accessor->body if blessed $accessor; |
26fbace8 |
374 | |
452bac1b |
375 | # install the delegation ... |
376 | my $associated_class = $self->associated_class; |
377 | foreach my $handle (keys %handles) { |
378 | my $method_to_call = $handles{$handle}; |
26fbace8 |
379 | |
452bac1b |
380 | (!$associated_class->has_method($handle)) |
381 | || confess "You cannot overwrite a locally defined method ($handle) with a delegation"; |
26fbace8 |
382 | |
d022f632 |
383 | # NOTE: |
384 | # handles is not allowed to delegate |
26fbace8 |
385 | # any of these methods, as they will |
386 | # override the ones in your class, which |
d022f632 |
387 | # is almost certainly not what you want. |
388 | next if $handle =~ /^BUILD|DEMOLISH$/ || Moose::Object->can($handle); |
26fbace8 |
389 | |
452bac1b |
390 | if ((reftype($method_to_call) || '') eq 'CODE') { |
26fbace8 |
391 | $associated_class->add_method($handle => $method_to_call); |
452bac1b |
392 | } |
393 | else { |
394 | $associated_class->add_method($handle => sub { |
b805c70c |
395 | # FIXME |
26fbace8 |
396 | # we should check for lack of |
397 | # a callable return value from |
398 | # the accessor here |
f3c4e20e |
399 | my $proxy = (shift)->$accessor(); |
cbe25729 |
400 | @_ = ($proxy, @_); |
f3c4e20e |
401 | goto &{ $proxy->can($method_to_call) }; |
452bac1b |
402 | }); |
403 | } |
404 | } |
405 | } |
26fbace8 |
406 | |
452bac1b |
407 | return; |
408 | } |
409 | |
98aae381 |
410 | # private methods to help delegation ... |
411 | |
452bac1b |
412 | sub _canonicalize_handles { |
413 | my $self = shift; |
414 | my $handles = $self->handles; |
c84f324f |
415 | if (my $handle_type = ref($handles)) { |
416 | if ($handle_type eq 'HASH') { |
417 | return %{$handles}; |
418 | } |
419 | elsif ($handle_type eq 'ARRAY') { |
420 | return map { $_ => $_ } @{$handles}; |
421 | } |
422 | elsif ($handle_type eq 'Regexp') { |
423 | ($self->has_type_constraint) |
424 | || confess "Cannot delegate methods based on a RegExpr without a type constraint (isa)"; |
26fbace8 |
425 | return map { ($_ => $_) } |
c84f324f |
426 | grep { /$handles/ } $self->_get_delegate_method_list; |
427 | } |
428 | elsif ($handle_type eq 'CODE') { |
429 | return $handles->($self, $self->_find_delegate_metaclass); |
430 | } |
431 | else { |
432 | confess "Unable to canonicalize the 'handles' option with $handles"; |
433 | } |
452bac1b |
434 | } |
435 | else { |
c84f324f |
436 | my $role_meta = eval { $handles->meta }; |
437 | if ($@) { |
26fbace8 |
438 | confess "Unable to canonicalize the 'handles' option with $handles because : $@"; |
c84f324f |
439 | } |
440 | |
441 | (blessed $role_meta && $role_meta->isa('Moose::Meta::Role')) |
442 | || confess "Unable to canonicalize the 'handles' option with $handles because ->meta is not a Moose::Meta::Role"; |
26fbace8 |
443 | |
c84f324f |
444 | return map { $_ => $_ } ( |
26fbace8 |
445 | $role_meta->get_method_list, |
c84f324f |
446 | $role_meta->get_required_method_list |
447 | ); |
452bac1b |
448 | } |
449 | } |
450 | |
451 | sub _find_delegate_metaclass { |
452 | my $self = shift; |
98aae381 |
453 | if (my $class = $self->_isa_metadata) { |
26fbace8 |
454 | # if the class does have |
452bac1b |
455 | # a meta method, use it |
456 | return $class->meta if $class->can('meta'); |
26fbace8 |
457 | # otherwise we might be |
452bac1b |
458 | # dealing with a non-Moose |
26fbace8 |
459 | # class, and need to make |
452bac1b |
460 | # our own metaclass |
461 | return Moose::Meta::Class->initialize($class); |
462 | } |
98aae381 |
463 | elsif (my $role = $self->_does_metadata) { |
26fbace8 |
464 | # our role will always have |
452bac1b |
465 | # a meta method |
98aae381 |
466 | return $role->meta; |
452bac1b |
467 | } |
468 | else { |
469 | confess "Cannot find delegate metaclass for attribute " . $self->name; |
470 | } |
471 | } |
472 | |
473 | sub _get_delegate_method_list { |
474 | my $self = shift; |
475 | my $meta = $self->_find_delegate_metaclass; |
476 | if ($meta->isa('Class::MOP::Class')) { |
093b12c2 |
477 | return map { $_->{name} } # NOTE: !never! delegate &meta |
26fbace8 |
478 | grep { $_->{class} ne 'Moose::Object' && $_->{name} ne 'meta' } |
452bac1b |
479 | $meta->compute_all_applicable_methods; |
480 | } |
481 | elsif ($meta->isa('Moose::Meta::Role')) { |
26fbace8 |
482 | return $meta->get_method_list; |
452bac1b |
483 | } |
484 | else { |
485 | confess "Unable to recognize the delegate metaclass '$meta'"; |
486 | } |
487 | } |
488 | |
c0e30cf5 |
489 | 1; |
490 | |
491 | __END__ |
492 | |
493 | =pod |
494 | |
495 | =head1 NAME |
496 | |
6ba6d68c |
497 | Moose::Meta::Attribute - The Moose attribute metaclass |
c0e30cf5 |
498 | |
499 | =head1 DESCRIPTION |
500 | |
26fbace8 |
501 | This is a subclass of L<Class::MOP::Attribute> with Moose specific |
502 | extensions. |
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503 | |
26fbace8 |
504 | For the most part, the only time you will ever encounter an |
505 | instance of this class is if you are doing some serious deep |
506 | introspection. To really understand this class, you need to refer |
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507 | to the L<Class::MOP::Attribute> documentation. |
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508 | |
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509 | =head1 METHODS |
510 | |
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511 | =head2 Overridden methods |
512 | |
26fbace8 |
513 | These methods override methods in L<Class::MOP::Attribute> and add |
514 | Moose specific features. You can safely assume though that they |
6ba6d68c |
515 | will behave just as L<Class::MOP::Attribute> does. |
516 | |
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517 | =over 4 |
518 | |
519 | =item B<new> |
520 | |
d500266f |
521 | =item B<initialize_instance_slot> |
522 | |
452bac1b |
523 | =item B<install_accessors> |
524 | |
39b3bc94 |
525 | =item B<accessor_metaclass> |
526 | |
946289d1 |
527 | =item B<get_value> |
528 | |
529 | =item B<set_value> |
530 | |
bcbaa845 |
531 | eval { $point->meta->get_attribute('x')->set_value($point, 'fourty-two') }; |
532 | if($@) { |
533 | print "Oops: $@\n"; |
534 | } |
535 | |
536 | I<Attribute (x) does not pass the type constraint (Int) with 'fourty-two'> |
537 | |
538 | Before setting the value, a check is made on the type constraint of |
539 | the attribute, if it has one, to see if the value passes it. If the |
540 | value fails to pass, the set operation dies with a L<Carp/confess>. |
541 | |
542 | Any coercion to convert values is done before checking the type constraint. |
543 | |
544 | To check a value against a type constraint before setting it, fetch the |
545 | attribute instance using L<Moose::Meta::Attribute/find_attribute_by_name>, |
546 | fetch the type_constraint from the attribute using L<Moose::Meta::Attribute/type_constraint> |
547 | and call L<Moose::Meta::TypeConstraint/check>. See L<Moose::Cookbook::RecipeX> |
548 | for an example. |
549 | |
a15dff8d |
550 | =back |
551 | |
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552 | =head2 Additional Moose features |
553 | |
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554 | Moose attributes support type-constraint checking, weak reference |
555 | creation and type coercion. |
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556 | |
a15dff8d |
557 | =over 4 |
558 | |
9e93dd19 |
559 | =item B<clone_and_inherit_options> |
560 | |
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561 | This is to support the C<has '+foo'> feature, it clones an attribute |
562 | from a superclass and allows a very specific set of changes to be made |
9e93dd19 |
563 | to the attribute. |
564 | |
a15dff8d |
565 | =item B<has_type_constraint> |
566 | |
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567 | Returns true if this meta-attribute has a type constraint. |
568 | |
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569 | =item B<type_constraint> |
570 | |
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571 | A read-only accessor for this meta-attribute's type constraint. For |
572 | more information on what you can do with this, see the documentation |
6ba6d68c |
573 | for L<Moose::Meta::TypeConstraint>. |
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574 | |
452bac1b |
575 | =item B<has_handles> |
576 | |
577 | Returns true if this meta-attribute performs delegation. |
578 | |
579 | =item B<handles> |
580 | |
581 | This returns the value which was passed into the handles option. |
582 | |
6ba6d68c |
583 | =item B<is_weak_ref> |
a15dff8d |
584 | |
02a0fb52 |
585 | Returns true if this meta-attribute produces a weak reference. |
4b598ea3 |
586 | |
ca01a97b |
587 | =item B<is_required> |
588 | |
02a0fb52 |
589 | Returns true if this meta-attribute is required to have a value. |
ca01a97b |
590 | |
591 | =item B<is_lazy> |
592 | |
02a0fb52 |
593 | Returns true if this meta-attribute should be initialized lazily. |
ca01a97b |
594 | |
26fbace8 |
595 | NOTE: lazy attributes, B<must> have a C<default> or C<builder> field set. |
596 | |
597 | =item B<is_lazy_build> |
598 | |
599 | Returns true if this meta-attribute should be initialized lazily through |
600 | the builder generated by lazy_build. Using C<lazy_build =E<gt> 1> will |
601 | make your attribute required and lazy. In addition it will set the builder, clearer |
602 | and predicate options for you using the following convention. |
603 | |
604 | #If your attribute name starts with an underscore: |
605 | has '_foo' => (lazy_build => 1); |
606 | #is the same as |
58f85113 |
607 | has '_foo' => (lazy => 1, required => 1, predicate => '_has_foo', clearer => '_clear_foo', builder => '_build__foo); |
26fbace8 |
608 | # or |
58f85113 |
609 | has '_foo' => (lazy => 1, required => 1, predicate => '_has_foo', clearer => '_clear_foo', default => sub{shift->_build__foo}); |
26fbace8 |
610 | |
611 | #If your attribute name does not start with an underscore: |
58f85113 |
612 | has 'foo' => (lazy_build => 1); |
613 | #is the same as |
614 | has 'foo' => (lazy => 1, required => 1, predicate => 'has_foo', clearer => 'clear_foo', builder => '_build_foo); |
26fbace8 |
615 | # or |
58f85113 |
616 | has 'foo' => (lazy => 1, required => 1, predicate => 'has_foo', clearer => 'clear_foo', default => sub{shift->_build_foo}); |
617 | |
618 | The reason for the different naming of the C<builder> is that the C<builder> |
619 | method is a private method while the C<clearer> and C<predicate> methods |
620 | are public methods. |
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621 | |
622 | NOTE: This means your class should provide a method whose name matches the value |
58f85113 |
623 | of the builder part, in this case _build__foo or _build_foo. |
ca01a97b |
624 | |
34a66aa3 |
625 | =item B<should_coerce> |
4b598ea3 |
626 | |
02a0fb52 |
627 | Returns true if this meta-attribute should perform type coercion. |
6ba6d68c |
628 | |
536f0b17 |
629 | =item B<should_auto_deref> |
630 | |
26fbace8 |
631 | Returns true if this meta-attribute should perform automatic |
632 | auto-dereferencing. |
536f0b17 |
633 | |
26fbace8 |
634 | NOTE: This can only be done for attributes whose type constraint is |
536f0b17 |
635 | either I<ArrayRef> or I<HashRef>. |
636 | |
8c9d74e7 |
637 | =item B<has_trigger> |
638 | |
02a0fb52 |
639 | Returns true if this meta-attribute has a trigger set. |
640 | |
8c9d74e7 |
641 | =item B<trigger> |
642 | |
26fbace8 |
643 | This is a CODE reference which will be executed every time the |
644 | value of an attribute is assigned. The CODE ref will get two values, |
645 | the invocant and the new value. This can be used to handle I<basic> |
02a0fb52 |
646 | bi-directional relations. |
647 | |
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648 | =item B<documentation> |
649 | |
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650 | This is a string which contains the documentation for this attribute. |
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651 | It serves no direct purpose right now, but it might in the future |
652 | in some kind of automated documentation system perhaps. |
653 | |
654 | =item B<has_documentation> |
655 | |
656 | Returns true if this meta-attribute has any documentation. |
657 | |
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658 | =back |
659 | |
660 | =head1 BUGS |
661 | |
26fbace8 |
662 | All complex software has bugs lurking in it, and this module is no |
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663 | exception. If you find a bug please either email me, or add the bug |
664 | to cpan-RT. |
665 | |
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666 | =head1 AUTHOR |
667 | |
668 | Stevan Little E<lt>stevan@iinteractive.comE<gt> |
669 | |
98aae381 |
670 | Yuval Kogman E<lt>nothingmuch@woobling.comE<gt> |
671 | |
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672 | =head1 COPYRIGHT AND LICENSE |
673 | |
b77fdbed |
674 | Copyright 2006, 2007 by Infinity Interactive, Inc. |
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675 | |
676 | L<http://www.iinteractive.com> |
677 | |
678 | This library is free software; you can redistribute it and/or modify |
26fbace8 |
679 | it under the same terms as Perl itself. |
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680 | |
8a7a9c53 |
681 | =cut |