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'; |
7dbbdcab |
9 | use Sub::Name 'subname'; |
a909a4df |
10 | use overload (); |
a15dff8d |
11 | |
ccf49e80 |
12 | our $VERSION = '0.18'; |
d44714be |
13 | our $AUTHORITY = 'cpan:STEVAN'; |
78cd1d3b |
14 | |
8ee73eeb |
15 | use Moose::Meta::Method::Accessor; |
a3c7e2fe |
16 | use Moose::Util::TypeConstraints (); |
bc1e29b5 |
17 | |
c0e30cf5 |
18 | use base 'Class::MOP::Attribute'; |
19 | |
452bac1b |
20 | # options which are not directly used |
21 | # but we store them for metadata purposes |
98aae381 |
22 | __PACKAGE__->meta->add_attribute('isa' => (reader => '_isa_metadata')); |
23 | __PACKAGE__->meta->add_attribute('does' => (reader => '_does_metadata')); |
24 | __PACKAGE__->meta->add_attribute('is' => (reader => '_is_metadata')); |
452bac1b |
25 | |
26 | # these are actual options for the attrs |
1a563243 |
27 | __PACKAGE__->meta->add_attribute('required' => (reader => 'is_required' )); |
28 | __PACKAGE__->meta->add_attribute('lazy' => (reader => 'is_lazy' )); |
26fbace8 |
29 | __PACKAGE__->meta->add_attribute('lazy_build' => (reader => 'is_lazy_build' )); |
1a563243 |
30 | __PACKAGE__->meta->add_attribute('coerce' => (reader => 'should_coerce' )); |
31 | __PACKAGE__->meta->add_attribute('weak_ref' => (reader => 'is_weak_ref' )); |
32 | __PACKAGE__->meta->add_attribute('auto_deref' => (reader => 'should_auto_deref')); |
82168dbb |
33 | __PACKAGE__->meta->add_attribute('type_constraint' => ( |
34 | reader => 'type_constraint', |
35 | predicate => 'has_type_constraint', |
36 | )); |
8c9d74e7 |
37 | __PACKAGE__->meta->add_attribute('trigger' => ( |
38 | reader => 'trigger', |
39 | predicate => 'has_trigger', |
40 | )); |
452bac1b |
41 | __PACKAGE__->meta->add_attribute('handles' => ( |
42 | reader => 'handles', |
43 | predicate => 'has_handles', |
44 | )); |
ddbdc0cb |
45 | __PACKAGE__->meta->add_attribute('documentation' => ( |
46 | reader => 'documentation', |
47 | predicate => 'has_documentation', |
48 | )); |
82168dbb |
49 | |
78cd1d3b |
50 | sub new { |
f3c4e20e |
51 | my ($class, $name, %options) = @_; |
52 | $class->_process_options($name, \%options); |
53 | return $class->SUPER::new($name, %options); |
1d768fb1 |
54 | } |
55 | |
ce0e8d63 |
56 | sub clone_and_inherit_options { |
57 | my ($self, %options) = @_; |
83cc9094 |
58 | # you can change default, required, coerce, documentation and lazy |
ce0e8d63 |
59 | my %actual_options; |
83cc9094 |
60 | foreach my $legal_option (qw(default coerce required documentation lazy)) { |
ce0e8d63 |
61 | if (exists $options{$legal_option}) { |
62 | $actual_options{$legal_option} = $options{$legal_option}; |
63 | delete $options{$legal_option}; |
64 | } |
65 | } |
26fbace8 |
66 | |
83cc9094 |
67 | # handles can only be added, not changed |
68 | if ($options{handles}) { |
69 | confess "You can only add the 'handles' option, you cannot change it" |
70 | if $self->has_handles; |
71 | $actual_options{handles} = $options{handles}; |
72 | delete $options{handles}; |
73 | } |
26fbace8 |
74 | |
75 | # isa can be changed, but only if the |
76 | # new type is a subtype |
ce0e8d63 |
77 | if ($options{isa}) { |
78 | my $type_constraint; |
8de73ff1 |
79 | if (blessed($options{isa}) && $options{isa}->isa('Moose::Meta::TypeConstraint')) { |
80 | $type_constraint = $options{isa}; |
81 | } |
82 | else { |
83 | $type_constraint = Moose::Util::TypeConstraints::find_or_create_type_constraint( |
84 | $options{isa} |
85 | ); |
86 | (defined $type_constraint) |
87 | || confess "Could not find the type constraint '" . $options{isa} . "'"; |
88 | } |
89 | # NOTE: |
90 | # check here to see if the new type |
91 | # is a subtype of the old one |
92 | ($type_constraint->is_subtype_of($self->type_constraint->name)) |
93 | || confess "New type constraint setting must be a subtype of inherited one" |
94 | # iff we have a type constraint that is ... |
95 | if $self->has_type_constraint; |
96 | # then we use it :) |
97 | $actual_options{type_constraint} = $type_constraint; |
ce0e8d63 |
98 | delete $options{isa}; |
99 | } |
26fbace8 |
100 | (scalar keys %options == 0) |
ce0e8d63 |
101 | || confess "Illegal inherited options => (" . (join ', ' => keys %options) . ")"; |
102 | $self->clone(%actual_options); |
1d768fb1 |
103 | } |
104 | |
105 | sub _process_options { |
106 | my ($class, $name, $options) = @_; |
8de73ff1 |
107 | |
f3c4e20e |
108 | if (exists $options->{is}) { |
8de73ff1 |
109 | if ($options->{is} eq 'ro') { |
110 | $options->{reader} ||= $name; |
111 | (!exists $options->{trigger}) |
112 | || confess "Cannot have a trigger on a read-only attribute"; |
113 | } |
114 | elsif ($options->{is} eq 'rw') { |
115 | $options->{accessor} = $name; |
116 | ((reftype($options->{trigger}) || '') eq 'CODE') |
117 | || confess "Trigger must be a CODE ref" |
118 | if exists $options->{trigger}; |
119 | } |
120 | else { |
121 | confess "I do not understand this option (is => " . $options->{is} . ")" |
122 | } |
f3c4e20e |
123 | } |
8de73ff1 |
124 | |
f3c4e20e |
125 | if (exists $options->{isa}) { |
f3c4e20e |
126 | if (exists $options->{does}) { |
127 | if (eval { $options->{isa}->can('does') }) { |
128 | ($options->{isa}->does($options->{does})) |
129 | || confess "Cannot have an isa option and a does option if the isa does not do the does"; |
130 | } |
131 | else { |
132 | confess "Cannot have an isa option which cannot ->does()"; |
26fbace8 |
133 | } |
26fbace8 |
134 | } |
8de73ff1 |
135 | |
f3c4e20e |
136 | # allow for anon-subtypes here ... |
137 | if (blessed($options->{isa}) && $options->{isa}->isa('Moose::Meta::TypeConstraint')) { |
8de73ff1 |
138 | $options->{type_constraint} = $options->{isa}; |
139 | } |
140 | else { |
141 | $options->{type_constraint} = Moose::Util::TypeConstraints::find_or_create_type_constraint( |
142 | $options->{isa} => { |
f3c4e20e |
143 | parent => Moose::Util::TypeConstraints::find_type_constraint('Object'), |
144 | constraint => sub { $_[0]->isa($options->{isa}) } |
26fbace8 |
145 | } |
8de73ff1 |
146 | ); |
147 | } |
f3c4e20e |
148 | } |
149 | elsif (exists $options->{does}) { |
150 | # allow for anon-subtypes here ... |
151 | if (blessed($options->{does}) && $options->{does}->isa('Moose::Meta::TypeConstraint')) { |
238b424d |
152 | $options->{type_constraint} = $options->{does}; |
8de73ff1 |
153 | } |
154 | else { |
155 | $options->{type_constraint} = Moose::Util::TypeConstraints::find_or_create_type_constraint( |
156 | $options->{does} => { |
f3c4e20e |
157 | parent => Moose::Util::TypeConstraints::find_type_constraint('Role'), |
238b424d |
158 | constraint => sub { |
159 | Moose::Util::does_role($_[0], $options->{does}) |
160 | } |
26fbace8 |
161 | } |
8de73ff1 |
162 | ); |
163 | } |
f3c4e20e |
164 | } |
8de73ff1 |
165 | |
f3c4e20e |
166 | if (exists $options->{coerce} && $options->{coerce}) { |
167 | (exists $options->{type_constraint}) |
168 | || confess "You cannot have coercion without specifying a type constraint"; |
8de73ff1 |
169 | confess "You cannot have a weak reference to a coerced value" |
170 | if $options->{weak_ref}; |
f3c4e20e |
171 | } |
8de73ff1 |
172 | |
f3c4e20e |
173 | if (exists $options->{auto_deref} && $options->{auto_deref}) { |
174 | (exists $options->{type_constraint}) |
175 | || confess "You cannot auto-dereference without specifying a type constraint"; |
176 | ($options->{type_constraint}->is_a_type_of('ArrayRef') || |
8de73ff1 |
177 | $options->{type_constraint}->is_a_type_of('HashRef')) |
f3c4e20e |
178 | || confess "You cannot auto-dereference anything other than a ArrayRef or HashRef"; |
179 | } |
8de73ff1 |
180 | |
f3c4e20e |
181 | if (exists $options->{lazy_build} && $options->{lazy_build} == 1) { |
182 | confess("You can not use lazy_build and default for the same attribute") |
8de73ff1 |
183 | if exists $options->{default}; |
a6c84c69 |
184 | $options->{lazy} = 1; |
185 | $options->{required} = 1; |
186 | $options->{builder} ||= "_build_${name}"; |
187 | if ($name =~ /^_/) { |
f3c4e20e |
188 | $options->{clearer} ||= "_clear${name}"; |
189 | $options->{predicate} ||= "_has${name}"; |
a6c84c69 |
190 | } |
191 | else { |
f3c4e20e |
192 | $options->{clearer} ||= "clear_${name}"; |
193 | $options->{predicate} ||= "has_${name}"; |
26fbace8 |
194 | } |
f3c4e20e |
195 | } |
8de73ff1 |
196 | |
f3c4e20e |
197 | if (exists $options->{lazy} && $options->{lazy}) { |
9edba990 |
198 | (exists $options->{default} || defined $options->{builder} ) |
f3c4e20e |
199 | || confess "You cannot have lazy attribute without specifying a default value for it"; |
200 | } |
26fbace8 |
201 | |
9edba990 |
202 | if ( $options->{required} && !( ( !exists $options->{init_arg} || defined $options->{init_arg} ) || exists $options->{default} || defined $options->{builder} ) ) { |
203 | confess "You cannot have a required attribute without a default, builder, or an init_arg"; |
204 | } |
205 | |
78cd1d3b |
206 | } |
c0e30cf5 |
207 | |
d500266f |
208 | sub initialize_instance_slot { |
ddd0ec20 |
209 | my ($self, $meta_instance, $instance, $params) = @_; |
d500266f |
210 | my $init_arg = $self->init_arg(); |
211 | # try to fetch the init arg from the %params ... |
ddd0ec20 |
212 | |
26fbace8 |
213 | my $val; |
1ed0b94f |
214 | my $value_is_set; |
625d571f |
215 | if ( defined($init_arg) and exists $params->{$init_arg}) { |
d500266f |
216 | $val = $params->{$init_arg}; |
2c78d811 |
217 | $value_is_set = 1; |
d500266f |
218 | } |
219 | else { |
220 | # skip it if it's lazy |
221 | return if $self->is_lazy; |
222 | # and die if it's required and doesn't have a default value |
26fbace8 |
223 | confess "Attribute (" . $self->name . ") is required" |
224 | if $self->is_required && !$self->has_default && !$self->has_builder; |
ddd0ec20 |
225 | |
1ed0b94f |
226 | # if nothing was in the %params, we can use the |
227 | # attribute's default value (if it has one) |
228 | if ($self->has_default) { |
229 | $val = $self->default($instance); |
230 | $value_is_set = 1; |
a6c84c69 |
231 | } |
232 | elsif ($self->has_builder) { |
233 | if (my $builder = $instance->can($self->builder)){ |
1ed0b94f |
234 | $val = $instance->$builder; |
235 | $value_is_set = 1; |
a6c84c69 |
236 | } |
237 | else { |
0b26305c |
238 | confess(blessed($instance)." does not support builder method '".$self->builder."' for attribute '" . $self->name . "'"); |
1ed0b94f |
239 | } |
a0748c37 |
240 | } |
26fbace8 |
241 | } |
242 | |
1ed0b94f |
243 | return unless $value_is_set; |
244 | |
245 | if ($self->has_type_constraint) { |
246 | my $type_constraint = $self->type_constraint; |
247 | if ($self->should_coerce && $type_constraint->has_coercion) { |
248 | $val = $type_constraint->coerce($val); |
d500266f |
249 | } |
1ed0b94f |
250 | (defined($type_constraint->check($val))) |
688fcdda |
251 | || confess "Attribute (" |
252 | . $self->name |
253 | . ") does not pass the type constraint because: " |
254 | . $type_constraint->get_message($val); |
1ed0b94f |
255 | } |
ddd0ec20 |
256 | |
759e4e8f |
257 | $self->set_initial_value($instance, $val); |
26fbace8 |
258 | $meta_instance->weaken_slot_value($instance, $self->name) |
a6c84c69 |
259 | if ref $val && $self->is_weak_ref; |
d500266f |
260 | } |
261 | |
d617b644 |
262 | ## Slot management |
9e93dd19 |
263 | |
946289d1 |
264 | sub set_value { |
265 | my ($self, $instance, $value) = @_; |
26fbace8 |
266 | |
946289d1 |
267 | my $attr_name = $self->name; |
26fbace8 |
268 | |
946289d1 |
269 | if ($self->is_required) { |
26fbace8 |
270 | defined($value) |
946289d1 |
271 | || confess "Attribute ($attr_name) is required, so cannot be set to undef"; |
272 | } |
26fbace8 |
273 | |
946289d1 |
274 | if ($self->has_type_constraint) { |
26fbace8 |
275 | |
946289d1 |
276 | my $type_constraint = $self->type_constraint; |
26fbace8 |
277 | |
946289d1 |
278 | if ($self->should_coerce) { |
26fbace8 |
279 | $value = $type_constraint->coerce($value); |
688fcdda |
280 | } |
42bc21a4 |
281 | $type_constraint->_compiled_type_constraint->($value) |
688fcdda |
282 | || confess "Attribute (" |
283 | . $self->name |
284 | . ") does not pass the type constraint because " |
285 | . $type_constraint->get_message($value) |
286 | if defined($value); |
946289d1 |
287 | } |
26fbace8 |
288 | |
946289d1 |
289 | my $meta_instance = Class::MOP::Class->initialize(blessed($instance)) |
290 | ->get_meta_instance; |
26fbace8 |
291 | |
292 | $meta_instance->set_slot_value($instance, $attr_name, $value); |
293 | |
946289d1 |
294 | if (ref $value && $self->is_weak_ref) { |
26fbace8 |
295 | $meta_instance->weaken_slot_value($instance, $attr_name); |
946289d1 |
296 | } |
26fbace8 |
297 | |
946289d1 |
298 | if ($self->has_trigger) { |
299 | $self->trigger->($instance, $value, $self); |
300 | } |
301 | } |
302 | |
303 | sub get_value { |
304 | my ($self, $instance) = @_; |
26fbace8 |
305 | |
946289d1 |
306 | if ($self->is_lazy) { |
8de73ff1 |
307 | unless ($self->has_value($instance)) { |
308 | if ($self->has_default) { |
309 | my $default = $self->default($instance); |
759e4e8f |
310 | $self->set_initial_value($instance, $default); |
8de73ff1 |
311 | } |
312 | if ( $self->has_builder ){ |
a6c84c69 |
313 | if (my $builder = $instance->can($self->builder)){ |
759e4e8f |
314 | $self->set_initial_value($instance, $instance->$builder); |
a6c84c69 |
315 | } |
316 | else { |
317 | confess(blessed($instance) |
318 | . " does not support builder method '" |
319 | . $self->builder |
320 | . "' for attribute '" |
321 | . $self->name |
322 | . "'"); |
26fbace8 |
323 | } |
a6c84c69 |
324 | } |
325 | else { |
759e4e8f |
326 | $self->set_initial_value($instance, undef); |
26fbace8 |
327 | } |
8de73ff1 |
328 | } |
946289d1 |
329 | } |
26fbace8 |
330 | |
946289d1 |
331 | if ($self->should_auto_deref) { |
26fbace8 |
332 | |
946289d1 |
333 | my $type_constraint = $self->type_constraint; |
334 | |
335 | if ($type_constraint->is_a_type_of('ArrayRef')) { |
336 | my $rv = $self->SUPER::get_value($instance); |
337 | return unless defined $rv; |
338 | return wantarray ? @{ $rv } : $rv; |
26fbace8 |
339 | } |
946289d1 |
340 | elsif ($type_constraint->is_a_type_of('HashRef')) { |
341 | my $rv = $self->SUPER::get_value($instance); |
342 | return unless defined $rv; |
343 | return wantarray ? %{ $rv } : $rv; |
26fbace8 |
344 | } |
946289d1 |
345 | else { |
346 | confess "Can not auto de-reference the type constraint '" . $type_constraint->name . "'"; |
347 | } |
26fbace8 |
348 | |
946289d1 |
349 | } |
350 | else { |
26fbace8 |
351 | |
946289d1 |
352 | return $self->SUPER::get_value($instance); |
26fbace8 |
353 | } |
946289d1 |
354 | } |
a15dff8d |
355 | |
26fbace8 |
356 | ## installing accessors |
c0e30cf5 |
357 | |
d617b644 |
358 | sub accessor_metaclass { 'Moose::Meta::Method::Accessor' } |
d7f17ebb |
359 | |
452bac1b |
360 | sub install_accessors { |
361 | my $self = shift; |
26fbace8 |
362 | $self->SUPER::install_accessors(@_); |
363 | |
452bac1b |
364 | if ($self->has_handles) { |
26fbace8 |
365 | |
452bac1b |
366 | # NOTE: |
367 | # Here we canonicalize the 'handles' option |
26fbace8 |
368 | # this will sort out any details and always |
369 | # return an hash of methods which we want |
452bac1b |
370 | # to delagate to, see that method for details |
371 | my %handles = $self->_canonicalize_handles(); |
26fbace8 |
372 | |
f3c4e20e |
373 | # find the accessor method for this attribute |
374 | my $accessor = $self->get_read_method_ref; |
375 | # then unpack it if we need too ... |
376 | $accessor = $accessor->body if blessed $accessor; |
26fbace8 |
377 | |
452bac1b |
378 | # install the delegation ... |
379 | my $associated_class = $self->associated_class; |
380 | foreach my $handle (keys %handles) { |
381 | my $method_to_call = $handles{$handle}; |
7dbbdcab |
382 | my $class_name = $associated_class->name; |
383 | my $name = "${class_name}::${handle}"; |
26fbace8 |
384 | |
452bac1b |
385 | (!$associated_class->has_method($handle)) |
386 | || confess "You cannot overwrite a locally defined method ($handle) with a delegation"; |
26fbace8 |
387 | |
d022f632 |
388 | # NOTE: |
389 | # handles is not allowed to delegate |
26fbace8 |
390 | # any of these methods, as they will |
391 | # override the ones in your class, which |
d022f632 |
392 | # is almost certainly not what you want. |
4fe78472 |
393 | |
394 | # FIXME warn when $handle was explicitly specified, but not if the source is a regex or something |
395 | #cluck("Not delegating method '$handle' because it is a core method") and |
396 | next if $class_name->isa("Moose::Object") and $handle =~ /^BUILD|DEMOLISH$/ || Moose::Object->can($handle); |
26fbace8 |
397 | |
452bac1b |
398 | if ((reftype($method_to_call) || '') eq 'CODE') { |
7dbbdcab |
399 | $associated_class->add_method($handle => subname $name, $method_to_call); |
452bac1b |
400 | } |
401 | else { |
7dbbdcab |
402 | $associated_class->add_method($handle => subname $name, sub { |
f3c4e20e |
403 | my $proxy = (shift)->$accessor(); |
cbe25729 |
404 | @_ = ($proxy, @_); |
ccf49e80 |
405 | (defined $proxy) |
406 | || confess "Cannot delegate $handle to $method_to_call because " . |
407 | "the value of " . $self->name . " is not defined"; |
7dbbdcab |
408 | goto &{ $proxy->can($method_to_call) || return }; |
452bac1b |
409 | }); |
410 | } |
411 | } |
412 | } |
26fbace8 |
413 | |
452bac1b |
414 | return; |
415 | } |
416 | |
98aae381 |
417 | # private methods to help delegation ... |
418 | |
452bac1b |
419 | sub _canonicalize_handles { |
420 | my $self = shift; |
421 | my $handles = $self->handles; |
c84f324f |
422 | if (my $handle_type = ref($handles)) { |
423 | if ($handle_type eq 'HASH') { |
424 | return %{$handles}; |
425 | } |
426 | elsif ($handle_type eq 'ARRAY') { |
427 | return map { $_ => $_ } @{$handles}; |
428 | } |
429 | elsif ($handle_type eq 'Regexp') { |
430 | ($self->has_type_constraint) |
431 | || confess "Cannot delegate methods based on a RegExpr without a type constraint (isa)"; |
26fbace8 |
432 | return map { ($_ => $_) } |
c84f324f |
433 | grep { /$handles/ } $self->_get_delegate_method_list; |
434 | } |
435 | elsif ($handle_type eq 'CODE') { |
436 | return $handles->($self, $self->_find_delegate_metaclass); |
437 | } |
438 | else { |
439 | confess "Unable to canonicalize the 'handles' option with $handles"; |
440 | } |
452bac1b |
441 | } |
442 | else { |
c84f324f |
443 | my $role_meta = eval { $handles->meta }; |
444 | if ($@) { |
26fbace8 |
445 | confess "Unable to canonicalize the 'handles' option with $handles because : $@"; |
c84f324f |
446 | } |
447 | |
448 | (blessed $role_meta && $role_meta->isa('Moose::Meta::Role')) |
449 | || confess "Unable to canonicalize the 'handles' option with $handles because ->meta is not a Moose::Meta::Role"; |
26fbace8 |
450 | |
c84f324f |
451 | return map { $_ => $_ } ( |
26fbace8 |
452 | $role_meta->get_method_list, |
c84f324f |
453 | $role_meta->get_required_method_list |
454 | ); |
452bac1b |
455 | } |
456 | } |
457 | |
458 | sub _find_delegate_metaclass { |
459 | my $self = shift; |
98aae381 |
460 | if (my $class = $self->_isa_metadata) { |
26fbace8 |
461 | # if the class does have |
452bac1b |
462 | # a meta method, use it |
463 | return $class->meta if $class->can('meta'); |
26fbace8 |
464 | # otherwise we might be |
452bac1b |
465 | # dealing with a non-Moose |
26fbace8 |
466 | # class, and need to make |
452bac1b |
467 | # our own metaclass |
468 | return Moose::Meta::Class->initialize($class); |
469 | } |
98aae381 |
470 | elsif (my $role = $self->_does_metadata) { |
26fbace8 |
471 | # our role will always have |
452bac1b |
472 | # a meta method |
98aae381 |
473 | return $role->meta; |
452bac1b |
474 | } |
475 | else { |
476 | confess "Cannot find delegate metaclass for attribute " . $self->name; |
477 | } |
478 | } |
479 | |
480 | sub _get_delegate_method_list { |
481 | my $self = shift; |
482 | my $meta = $self->_find_delegate_metaclass; |
483 | if ($meta->isa('Class::MOP::Class')) { |
093b12c2 |
484 | return map { $_->{name} } # NOTE: !never! delegate &meta |
26fbace8 |
485 | grep { $_->{class} ne 'Moose::Object' && $_->{name} ne 'meta' } |
452bac1b |
486 | $meta->compute_all_applicable_methods; |
487 | } |
488 | elsif ($meta->isa('Moose::Meta::Role')) { |
26fbace8 |
489 | return $meta->get_method_list; |
452bac1b |
490 | } |
491 | else { |
492 | confess "Unable to recognize the delegate metaclass '$meta'"; |
493 | } |
494 | } |
495 | |
c0e30cf5 |
496 | 1; |
497 | |
498 | __END__ |
499 | |
500 | =pod |
501 | |
502 | =head1 NAME |
503 | |
6ba6d68c |
504 | Moose::Meta::Attribute - The Moose attribute metaclass |
c0e30cf5 |
505 | |
506 | =head1 DESCRIPTION |
507 | |
26fbace8 |
508 | This is a subclass of L<Class::MOP::Attribute> with Moose specific |
509 | extensions. |
6ba6d68c |
510 | |
26fbace8 |
511 | For the most part, the only time you will ever encounter an |
512 | instance of this class is if you are doing some serious deep |
513 | introspection. To really understand this class, you need to refer |
6ba6d68c |
514 | to the L<Class::MOP::Attribute> documentation. |
e522431d |
515 | |
c0e30cf5 |
516 | =head1 METHODS |
517 | |
6ba6d68c |
518 | =head2 Overridden methods |
519 | |
26fbace8 |
520 | These methods override methods in L<Class::MOP::Attribute> and add |
521 | Moose specific features. You can safely assume though that they |
6ba6d68c |
522 | will behave just as L<Class::MOP::Attribute> does. |
523 | |
c0e30cf5 |
524 | =over 4 |
525 | |
526 | =item B<new> |
527 | |
d500266f |
528 | =item B<initialize_instance_slot> |
529 | |
452bac1b |
530 | =item B<install_accessors> |
531 | |
39b3bc94 |
532 | =item B<accessor_metaclass> |
533 | |
946289d1 |
534 | =item B<get_value> |
535 | |
536 | =item B<set_value> |
537 | |
bcbaa845 |
538 | eval { $point->meta->get_attribute('x')->set_value($point, 'fourty-two') }; |
539 | if($@) { |
540 | print "Oops: $@\n"; |
541 | } |
542 | |
543 | I<Attribute (x) does not pass the type constraint (Int) with 'fourty-two'> |
544 | |
545 | Before setting the value, a check is made on the type constraint of |
546 | the attribute, if it has one, to see if the value passes it. If the |
547 | value fails to pass, the set operation dies with a L<Carp/confess>. |
548 | |
549 | Any coercion to convert values is done before checking the type constraint. |
550 | |
551 | To check a value against a type constraint before setting it, fetch the |
ec00fa75 |
552 | attribute instance using L<Class::MOP::Class/find_attribute_by_name>, |
bcbaa845 |
553 | fetch the type_constraint from the attribute using L<Moose::Meta::Attribute/type_constraint> |
554 | and call L<Moose::Meta::TypeConstraint/check>. See L<Moose::Cookbook::RecipeX> |
555 | for an example. |
556 | |
a15dff8d |
557 | =back |
558 | |
6ba6d68c |
559 | =head2 Additional Moose features |
560 | |
26fbace8 |
561 | Moose attributes support type-constraint checking, weak reference |
562 | creation and type coercion. |
6ba6d68c |
563 | |
a15dff8d |
564 | =over 4 |
565 | |
9e93dd19 |
566 | =item B<clone_and_inherit_options> |
567 | |
26fbace8 |
568 | This is to support the C<has '+foo'> feature, it clones an attribute |
569 | from a superclass and allows a very specific set of changes to be made |
9e93dd19 |
570 | to the attribute. |
571 | |
a15dff8d |
572 | =item B<has_type_constraint> |
573 | |
6ba6d68c |
574 | Returns true if this meta-attribute has a type constraint. |
575 | |
a15dff8d |
576 | =item B<type_constraint> |
577 | |
26fbace8 |
578 | A read-only accessor for this meta-attribute's type constraint. For |
579 | more information on what you can do with this, see the documentation |
6ba6d68c |
580 | for L<Moose::Meta::TypeConstraint>. |
a15dff8d |
581 | |
452bac1b |
582 | =item B<has_handles> |
583 | |
584 | Returns true if this meta-attribute performs delegation. |
585 | |
586 | =item B<handles> |
587 | |
588 | This returns the value which was passed into the handles option. |
589 | |
6ba6d68c |
590 | =item B<is_weak_ref> |
a15dff8d |
591 | |
02a0fb52 |
592 | Returns true if this meta-attribute produces a weak reference. |
4b598ea3 |
593 | |
ca01a97b |
594 | =item B<is_required> |
595 | |
02a0fb52 |
596 | Returns true if this meta-attribute is required to have a value. |
ca01a97b |
597 | |
598 | =item B<is_lazy> |
599 | |
02a0fb52 |
600 | Returns true if this meta-attribute should be initialized lazily. |
ca01a97b |
601 | |
26fbace8 |
602 | NOTE: lazy attributes, B<must> have a C<default> or C<builder> field set. |
603 | |
604 | =item B<is_lazy_build> |
605 | |
606 | Returns true if this meta-attribute should be initialized lazily through |
607 | the builder generated by lazy_build. Using C<lazy_build =E<gt> 1> will |
608 | make your attribute required and lazy. In addition it will set the builder, clearer |
609 | and predicate options for you using the following convention. |
610 | |
611 | #If your attribute name starts with an underscore: |
612 | has '_foo' => (lazy_build => 1); |
613 | #is the same as |
58f85113 |
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}); |
26fbace8 |
617 | |
618 | #If your attribute name does not start with an underscore: |
58f85113 |
619 | has 'foo' => (lazy_build => 1); |
620 | #is the same as |
621 | has 'foo' => (lazy => 1, required => 1, predicate => 'has_foo', clearer => 'clear_foo', builder => '_build_foo); |
26fbace8 |
622 | # or |
58f85113 |
623 | has 'foo' => (lazy => 1, required => 1, predicate => 'has_foo', clearer => 'clear_foo', default => sub{shift->_build_foo}); |
624 | |
625 | The reason for the different naming of the C<builder> is that the C<builder> |
626 | method is a private method while the C<clearer> and C<predicate> methods |
627 | are public methods. |
26fbace8 |
628 | |
629 | NOTE: This means your class should provide a method whose name matches the value |
58f85113 |
630 | of the builder part, in this case _build__foo or _build_foo. |
ca01a97b |
631 | |
34a66aa3 |
632 | =item B<should_coerce> |
4b598ea3 |
633 | |
02a0fb52 |
634 | Returns true if this meta-attribute should perform type coercion. |
6ba6d68c |
635 | |
536f0b17 |
636 | =item B<should_auto_deref> |
637 | |
26fbace8 |
638 | Returns true if this meta-attribute should perform automatic |
639 | auto-dereferencing. |
536f0b17 |
640 | |
26fbace8 |
641 | NOTE: This can only be done for attributes whose type constraint is |
536f0b17 |
642 | either I<ArrayRef> or I<HashRef>. |
643 | |
8c9d74e7 |
644 | =item B<has_trigger> |
645 | |
02a0fb52 |
646 | Returns true if this meta-attribute has a trigger set. |
647 | |
8c9d74e7 |
648 | =item B<trigger> |
649 | |
26fbace8 |
650 | This is a CODE reference which will be executed every time the |
651 | value of an attribute is assigned. The CODE ref will get two values, |
652 | the invocant and the new value. This can be used to handle I<basic> |
02a0fb52 |
653 | bi-directional relations. |
654 | |
ddbdc0cb |
655 | =item B<documentation> |
656 | |
26fbace8 |
657 | This is a string which contains the documentation for this attribute. |
ddbdc0cb |
658 | It serves no direct purpose right now, but it might in the future |
659 | in some kind of automated documentation system perhaps. |
660 | |
661 | =item B<has_documentation> |
662 | |
663 | Returns true if this meta-attribute has any documentation. |
664 | |
c0e30cf5 |
665 | =back |
666 | |
667 | =head1 BUGS |
668 | |
26fbace8 |
669 | All complex software has bugs lurking in it, and this module is no |
c0e30cf5 |
670 | exception. If you find a bug please either email me, or add the bug |
671 | to cpan-RT. |
672 | |
c0e30cf5 |
673 | =head1 AUTHOR |
674 | |
675 | Stevan Little E<lt>stevan@iinteractive.comE<gt> |
676 | |
98aae381 |
677 | Yuval Kogman E<lt>nothingmuch@woobling.comE<gt> |
678 | |
c0e30cf5 |
679 | =head1 COPYRIGHT AND LICENSE |
680 | |
778db3ac |
681 | Copyright 2006-2008 by Infinity Interactive, Inc. |
c0e30cf5 |
682 | |
683 | L<http://www.iinteractive.com> |
684 | |
685 | This library is free software; you can redistribute it and/or modify |
26fbace8 |
686 | it under the same terms as Perl itself. |
c0e30cf5 |
687 | |
8a7a9c53 |
688 | =cut |