Commit | Line | Data |
8b978dd5 |
1 | |
2 | package Class::MOP::Attribute; |
3 | |
4 | use strict; |
5 | use warnings; |
6 | |
ba38bf08 |
7 | use Class::MOP::Method::Accessor; |
32b01180 |
8 | use Class::MOP::Method::Reader; |
9 | use Class::MOP::Method::Writer; |
ba38bf08 |
10 | |
2eb717d5 |
11 | use Carp 'confess'; |
9b522fc4 |
12 | use Scalar::Util 'blessed', 'weaken'; |
2eb717d5 |
13 | |
f6ca0704 |
14 | our $VERSION = '0.94'; |
d519662a |
15 | $VERSION = eval $VERSION; |
f0480c45 |
16 | our $AUTHORITY = 'cpan:STEVAN'; |
8b978dd5 |
17 | |
b1897d4d |
18 | use base 'Class::MOP::Object'; |
19 | |
727919c5 |
20 | # NOTE: (meta-circularity) |
1d68af04 |
21 | # This method will be replaced in the |
22 | # boostrap section of Class::MOP, by |
23 | # a new version which uses the |
727919c5 |
24 | # &Class::MOP::Class::construct_instance |
25 | # method to build an attribute meta-object |
26 | # which itself is described with attribute |
1d68af04 |
27 | # meta-objects. |
727919c5 |
28 | # - Ain't meta-circularity grand? :) |
8b978dd5 |
29 | sub new { |
649efb63 |
30 | my ( $class, @args ) = @_; |
31 | |
32 | unshift @args, "name" if @args % 2 == 1; |
33 | my %options = @args; |
34 | |
35 | my $name = $options{name}; |
1d68af04 |
36 | |
d9330488 |
37 | (defined $name) |
8b978dd5 |
38 | || confess "You must provide a name for the attribute"; |
1d68af04 |
39 | |
40 | $options{init_arg} = $name |
5659d76e |
41 | if not exists $options{init_arg}; |
1d68af04 |
42 | if(exists $options{builder}){ |
43 | confess("builder must be a defined scalar value which is a method name") |
44 | if ref $options{builder} || !(defined $options{builder}); |
45 | confess("Setting both default and builder is not allowed.") |
46 | if exists $options{default}; |
8fe581e5 |
47 | } else { |
48 | (is_default_a_coderef(\%options)) |
49 | || confess("References are not allowed as default values, you must ". |
3c0a8087 |
50 | "wrap the default of '$name' in a CODE reference (ex: sub { [] } and not [])") |
8fe581e5 |
51 | if exists $options{default} && ref $options{default}; |
1d68af04 |
52 | } |
2e877f58 |
53 | if( $options{required} and not( defined($options{builder}) || defined($options{init_arg}) || exists $options{default} ) ) { |
54 | confess("A required attribute must have either 'init_arg', 'builder', or 'default'"); |
55 | } |
8683db0e |
56 | |
cb75020f |
57 | $class->_new(\%options); |
4b698b1a |
58 | } |
59 | |
60 | sub _new { |
0bfc85b8 |
61 | my $class = shift; |
ec9e38e5 |
62 | |
63 | return Class::MOP::Class->initialize($class)->new_object(@_) |
812d58f9 |
64 | if $class ne __PACKAGE__; |
ec9e38e5 |
65 | |
0bfc85b8 |
66 | my $options = @_ == 1 ? $_[0] : {@_}; |
4b698b1a |
67 | |
8b978dd5 |
68 | bless { |
d9d99689 |
69 | 'name' => $options->{name}, |
70 | 'accessor' => $options->{accessor}, |
71 | 'reader' => $options->{reader}, |
72 | 'writer' => $options->{writer}, |
73 | 'predicate' => $options->{predicate}, |
74 | 'clearer' => $options->{clearer}, |
75 | 'builder' => $options->{builder}, |
76 | 'init_arg' => $options->{init_arg}, |
77 | 'default' => $options->{default}, |
78 | 'initializer' => $options->{initializer}, |
79 | 'definition_context' => $options->{definition_context}, |
06a88dbb |
80 | 'lazy' => $options->{lazy}, |
1d68af04 |
81 | # keep a weakened link to the |
9ec169fe |
82 | # class we are associated with |
8683db0e |
83 | 'associated_class' => undef, |
1d68af04 |
84 | # and a list of the methods |
3545c727 |
85 | # associated with this attr |
8683db0e |
86 | 'associated_methods' => [], |
dc9d420c |
87 | # this let's us keep track of |
88 | # our order inside the associated |
89 | # class |
90 | 'insertion_order' => undef, |
0bfc85b8 |
91 | }, $class; |
8b978dd5 |
92 | } |
93 | |
7b31baf4 |
94 | # NOTE: |
1d68af04 |
95 | # this is a primative (and kludgy) clone operation |
16e960bd |
96 | # for now, it will be replaced in the Class::MOP |
1d68af04 |
97 | # bootstrap with a proper one, however we know |
5659d76e |
98 | # that this one will work fine for now. |
99 | sub clone { |
100 | my $self = shift; |
101 | my %options = @_; |
102 | (blessed($self)) |
103 | || confess "Can only clone an instance"; |
b3fa93c7 |
104 | return bless { %{$self}, %options } => ref($self); |
5659d76e |
105 | } |
106 | |
06a88dbb |
107 | sub _call_builder { |
108 | my ( $self, $instance ) = @_; |
109 | |
110 | my $builder = $self->builder(); |
111 | |
112 | return $instance->$builder() |
113 | if $instance->can( $self->builder ); |
114 | |
115 | $self->throw_error( blessed($instance) |
116 | . " does not support builder method '" |
117 | . $self->builder |
118 | . "' for attribute '" |
119 | . $self->name |
120 | . "'", |
121 | object => $instance, |
122 | ); |
123 | } |
124 | |
bd4e03f9 |
125 | sub initialize_instance_slot { |
f892c0f0 |
126 | my ($self, $meta_instance, $instance, $params) = @_; |
8683db0e |
127 | my $init_arg = $self->{'init_arg'}; |
128 | |
06a88dbb |
129 | my ($val, $value_is_set); |
bd4e03f9 |
130 | # try to fetch the init arg from the %params ... |
8d2d4c67 |
131 | |
1d68af04 |
132 | # if nothing was in the %params, we can use the |
bd4e03f9 |
133 | # attribute's default value (if it has one) |
2e877f58 |
134 | if(defined $init_arg and exists $params->{$init_arg}){ |
06a88dbb |
135 | $val = $params->{$init_arg}; |
136 | $value_is_set = 1; |
137 | } else { |
138 | return if $self->is_lazy; |
139 | |
140 | if($self->has_default){ |
141 | $val = $self->default($instance); |
142 | $value_is_set = 1; |
143 | } elsif($self->has_builder){ |
144 | $val = $self->_call_builder($instance); |
145 | $value_is_set = 1; |
8fe581e5 |
146 | } |
1d68af04 |
147 | } |
06a88dbb |
148 | |
149 | return unless $value_is_set; |
150 | |
151 | $self->_set_initial_slot_value( |
152 | $meta_instance, |
153 | $instance, |
154 | $val, |
155 | ); |
156 | |
bd4e03f9 |
157 | } |
158 | |
8ee74136 |
159 | sub _set_initial_slot_value { |
160 | my ($self, $meta_instance, $instance, $value) = @_; |
161 | |
162 | my $slot_name = $self->name; |
163 | |
164 | return $meta_instance->set_slot_value($instance, $slot_name, $value) |
165 | unless $self->has_initializer; |
166 | |
167 | my $callback = sub { |
168 | $meta_instance->set_slot_value($instance, $slot_name, $_[0]); |
169 | }; |
170 | |
171 | my $initializer = $self->initializer; |
172 | |
173 | # most things will just want to set a value, so make it first arg |
174 | $instance->$initializer($value, $callback, $self); |
175 | } |
176 | |
5659d76e |
177 | # NOTE: |
1d68af04 |
178 | # the next bunch of methods will get bootstrapped |
7b31baf4 |
179 | # away in the Class::MOP bootstrapping section |
180 | |
8683db0e |
181 | sub associated_class { $_[0]->{'associated_class'} } |
182 | sub associated_methods { $_[0]->{'associated_methods'} } |
183 | |
b3fa93c7 |
184 | sub has_accessor { defined($_[0]->{'accessor'}) } |
185 | sub has_reader { defined($_[0]->{'reader'}) } |
186 | sub has_writer { defined($_[0]->{'writer'}) } |
187 | sub has_predicate { defined($_[0]->{'predicate'}) } |
188 | sub has_clearer { defined($_[0]->{'clearer'}) } |
189 | sub has_builder { defined($_[0]->{'builder'}) } |
190 | sub has_init_arg { defined($_[0]->{'init_arg'}) } |
191 | sub has_default { defined($_[0]->{'default'}) } |
192 | sub has_initializer { defined($_[0]->{'initializer'}) } |
dc9d420c |
193 | sub has_insertion_order { defined($_[0]->{'insertion_order'}) } |
8683db0e |
194 | |
d9d99689 |
195 | sub accessor { $_[0]->{'accessor'} } |
196 | sub reader { $_[0]->{'reader'} } |
197 | sub writer { $_[0]->{'writer'} } |
198 | sub predicate { $_[0]->{'predicate'} } |
199 | sub clearer { $_[0]->{'clearer'} } |
200 | sub builder { $_[0]->{'builder'} } |
201 | sub init_arg { $_[0]->{'init_arg'} } |
202 | sub initializer { $_[0]->{'initializer'} } |
203 | sub definition_context { $_[0]->{'definition_context'} } |
dc9d420c |
204 | sub insertion_order { $_[0]->{'insertion_order'} } |
943cbe2d |
205 | sub _set_insertion_order { $_[0]->{'insertion_order'} = $_[1] } |
06a88dbb |
206 | sub is_lazy { $_[0]->{'lazy'} } |
c50c603e |
207 | |
7b31baf4 |
208 | # end bootstrapped away method section. |
209 | # (all methods below here are kept intact) |
210 | |
9e517e01 |
211 | sub has_read_method { $_[0]->has_reader || $_[0]->has_accessor } |
212 | sub has_write_method { $_[0]->has_writer || $_[0]->has_accessor } |
213 | |
d14f6cbe |
214 | sub get_read_method { |
215 | my $self = shift; |
216 | my $reader = $self->reader || $self->accessor; |
217 | # normal case ... |
218 | return $reader unless ref $reader; |
219 | # the HASH ref case |
220 | my ($name) = %$reader; |
221 | return $name; |
222 | } |
223 | |
224 | sub get_write_method { |
225 | my $self = shift; |
226 | my $writer = $self->writer || $self->accessor; |
227 | # normal case ... |
228 | return $writer unless ref $writer; |
229 | # the HASH ref case |
230 | my ($name) = %$writer; |
231 | return $name; |
232 | } |
b25109b1 |
233 | |
5da16d1b |
234 | sub get_read_method_ref { |
235 | my $self = shift; |
742fb371 |
236 | if ((my $reader = $self->get_read_method) && $self->associated_class) { |
5da16d1b |
237 | return $self->associated_class->get_method($reader); |
238 | } |
239 | else { |
def5c0b5 |
240 | my $code = sub { $self->get_value(@_) }; |
241 | if (my $class = $self->associated_class) { |
242 | return $class->method_metaclass->wrap( |
243 | $code, |
244 | package_name => $class->name, |
245 | name => '__ANON__' |
246 | ); |
247 | } |
248 | else { |
249 | return $code; |
250 | } |
5da16d1b |
251 | } |
252 | } |
253 | |
254 | sub get_write_method_ref { |
255 | my $self = shift; |
d14f6cbe |
256 | if ((my $writer = $self->get_write_method) && $self->associated_class) { |
742fb371 |
257 | return $self->associated_class->get_method($writer); |
5da16d1b |
258 | } |
259 | else { |
def5c0b5 |
260 | my $code = sub { $self->set_value(@_) }; |
261 | if (my $class = $self->associated_class) { |
262 | return $class->method_metaclass->wrap( |
263 | $code, |
264 | package_name => $class->name, |
265 | name => '__ANON__' |
266 | ); |
267 | } |
268 | else { |
269 | return $code; |
270 | } |
5da16d1b |
271 | } |
272 | } |
273 | |
1d68af04 |
274 | sub is_default_a_coderef { |
ed337aad |
275 | my ($value) = $_[0]->{'default'}; |
276 | return unless ref($value); |
277 | return ref($value) eq 'CODE' || (blessed($value) && $value->isa('Class::MOP::Method')); |
c0cbf4d9 |
278 | } |
279 | |
1d68af04 |
280 | sub default { |
c0cbf4d9 |
281 | my ($self, $instance) = @_; |
9363ea89 |
282 | if (defined $instance && $self->is_default_a_coderef) { |
1d68af04 |
283 | # if the default is a CODE ref, then |
727919c5 |
284 | # we pass in the instance and default |
1d68af04 |
285 | # can return a value based on that |
727919c5 |
286 | # instance. Somewhat crude, but works. |
8683db0e |
287 | return $self->{'default'}->($instance); |
1d68af04 |
288 | } |
8683db0e |
289 | $self->{'default'}; |
c50c603e |
290 | } |
8b978dd5 |
291 | |
c57c8b10 |
292 | # slots |
293 | |
294 | sub slots { (shift)->name } |
295 | |
1d68af04 |
296 | # class association |
727919c5 |
297 | |
9ec169fe |
298 | sub attach_to_class { |
299 | my ($self, $class) = @_; |
300 | (blessed($class) && $class->isa('Class::MOP::Class')) |
301 | || confess "You must pass a Class::MOP::Class instance (or a subclass)"; |
8683db0e |
302 | weaken($self->{'associated_class'} = $class); |
9ec169fe |
303 | } |
304 | |
305 | sub detach_from_class { |
306 | my $self = shift; |
8683db0e |
307 | $self->{'associated_class'} = undef; |
9ec169fe |
308 | } |
309 | |
1d68af04 |
310 | # method association |
3545c727 |
311 | |
312 | sub associate_method { |
313 | my ($self, $method) = @_; |
8683db0e |
314 | push @{$self->{'associated_methods'}} => $method; |
3545c727 |
315 | } |
316 | |
16e960bd |
317 | ## Slot management |
318 | |
ef91a0e2 |
319 | sub set_initial_value { |
320 | my ($self, $instance, $value) = @_; |
e76b01fb |
321 | $self->_set_initial_slot_value( |
b3fa93c7 |
322 | Class::MOP::Class->initialize(ref($instance))->get_meta_instance, |
8ee74136 |
323 | $instance, |
324 | $value |
325 | ); |
ef91a0e2 |
326 | } |
327 | |
7e5efe15 |
328 | sub set_value { shift->set_raw_value(@_) } |
329 | sub get_value { shift->get_raw_value(@_) } |
330 | |
331 | sub set_raw_value { |
1396f86b |
332 | my ($self, $instance, $value) = @_; |
16e960bd |
333 | |
b3fa93c7 |
334 | Class::MOP::Class->initialize(ref($instance)) |
da34f054 |
335 | ->get_meta_instance |
336 | ->set_slot_value($instance, $self->name, $value); |
16e960bd |
337 | } |
338 | |
7e5efe15 |
339 | sub get_raw_value { |
1396f86b |
340 | my ($self, $instance) = @_; |
16e960bd |
341 | |
06a88dbb |
342 | if($self->is_lazy && !$self->has_value($instance)){ |
343 | my $val; |
344 | |
345 | if($self->has_default){ |
346 | $val = $self->default($instance); |
347 | } elsif($self->has_builder){ |
348 | $val = $self->_call_builder($instance); |
349 | } |
350 | |
351 | $self->set_initial_value( |
352 | $instance, |
353 | $val, |
354 | ); |
355 | } |
356 | |
b3fa93c7 |
357 | Class::MOP::Class->initialize(ref($instance)) |
da34f054 |
358 | ->get_meta_instance |
359 | ->get_slot_value($instance, $self->name); |
16e960bd |
360 | } |
361 | |
3545c727 |
362 | sub has_value { |
363 | my ($self, $instance) = @_; |
1d68af04 |
364 | |
b3fa93c7 |
365 | Class::MOP::Class->initialize(ref($instance)) |
da34f054 |
366 | ->get_meta_instance |
367 | ->is_slot_initialized($instance, $self->name); |
3545c727 |
368 | } |
369 | |
370 | sub clear_value { |
371 | my ($self, $instance) = @_; |
1d68af04 |
372 | |
b3fa93c7 |
373 | Class::MOP::Class->initialize(ref($instance)) |
da34f054 |
374 | ->get_meta_instance |
375 | ->deinitialize_slot($instance, $self->name); |
3545c727 |
376 | } |
377 | |
ba38bf08 |
378 | ## load em up ... |
c0cbf4d9 |
379 | |
ba38bf08 |
380 | sub accessor_metaclass { 'Class::MOP::Method::Accessor' } |
32b01180 |
381 | sub method_metaclasses { |
382 | { |
383 | reader => 'Class::MOP::Method::Reader', |
8cfd8177 |
384 | writer => 'Class::MOP::Method::Writer', |
32b01180 |
385 | } |
386 | } |
c0cbf4d9 |
387 | |
45a183fb |
388 | sub _process_accessors { |
c0cbf4d9 |
389 | my ($self, $type, $accessor, $generate_as_inline_methods) = @_; |
d9d99689 |
390 | |
391 | my $method_ctx; |
392 | |
393 | if ( my $ctx = $self->definition_context ) { |
394 | $method_ctx = { %$ctx }; |
395 | } |
396 | |
9b522fc4 |
397 | if (ref($accessor)) { |
398 | (ref($accessor) eq 'HASH') |
7d28758b |
399 | || confess "bad accessor/reader/writer/predicate/clearer format, must be a HASH ref"; |
4d47b77f |
400 | my ($name, $method) = %{$accessor}; |
4c105333 |
401 | $method = $self->accessor_metaclass->wrap( |
402 | $method, |
403 | package_name => $self->associated_class->name, |
404 | name => $name, |
d9d99689 |
405 | definition_context => $method_ctx, |
4c105333 |
406 | ); |
3545c727 |
407 | $self->associate_method($method); |
1d68af04 |
408 | return ($name, $method); |
2eb717d5 |
409 | } |
9ec169fe |
410 | else { |
1d68af04 |
411 | my $inline_me = ($generate_as_inline_methods && $self->associated_class->instance_metaclass->is_inlinable); |
ba38bf08 |
412 | my $method; |
413 | eval { |
d9d99689 |
414 | if ( $method_ctx ) { |
415 | my $desc = "accessor $accessor"; |
416 | if ( $accessor ne $self->name ) { |
417 | $desc .= " of attribute " . $self->name; |
418 | } |
419 | |
420 | $method_ctx->{description} = $desc; |
421 | } |
422 | |
32b01180 |
423 | my $method_metaclass = $self->method_metaclasses->{$type} || $self->accessor_metaclass; |
424 | |
425 | $method = $method_metaclass->new( |
ba38bf08 |
426 | attribute => $self, |
d90b42a6 |
427 | is_inline => $inline_me, |
ba38bf08 |
428 | accessor_type => $type, |
4c105333 |
429 | package_name => $self->associated_class->name, |
430 | name => $accessor, |
d9d99689 |
431 | definition_context => $method_ctx, |
1d68af04 |
432 | ); |
ba38bf08 |
433 | }; |
1d68af04 |
434 | confess "Could not create the '$type' method for " . $self->name . " because : $@" if $@; |
3545c727 |
435 | $self->associate_method($method); |
ba38bf08 |
436 | return ($accessor, $method); |
1d68af04 |
437 | } |
9ec169fe |
438 | } |
439 | |
440 | sub install_accessors { |
c0cbf4d9 |
441 | my $self = shift; |
442 | my $inline = shift; |
443 | my $class = $self->associated_class; |
1d68af04 |
444 | |
9ec169fe |
445 | $class->add_method( |
45a183fb |
446 | $self->_process_accessors('accessor' => $self->accessor(), $inline) |
9ec169fe |
447 | ) if $self->has_accessor(); |
448 | |
1d68af04 |
449 | $class->add_method( |
45a183fb |
450 | $self->_process_accessors('reader' => $self->reader(), $inline) |
9ec169fe |
451 | ) if $self->has_reader(); |
452 | |
453 | $class->add_method( |
45a183fb |
454 | $self->_process_accessors('writer' => $self->writer(), $inline) |
9ec169fe |
455 | ) if $self->has_writer(); |
456 | |
457 | $class->add_method( |
45a183fb |
458 | $self->_process_accessors('predicate' => $self->predicate(), $inline) |
9ec169fe |
459 | ) if $self->has_predicate(); |
1d68af04 |
460 | |
7d28758b |
461 | $class->add_method( |
45a183fb |
462 | $self->_process_accessors('clearer' => $self->clearer(), $inline) |
7d28758b |
463 | ) if $self->has_clearer(); |
1d68af04 |
464 | |
9ec169fe |
465 | return; |
2eb717d5 |
466 | } |
467 | |
b51af7f9 |
468 | { |
469 | my $_remove_accessor = sub { |
470 | my ($accessor, $class) = @_; |
9b522fc4 |
471 | if (ref($accessor) && ref($accessor) eq 'HASH') { |
c50c603e |
472 | ($accessor) = keys %{$accessor}; |
1d68af04 |
473 | } |
474 | my $method = $class->get_method($accessor); |
475 | $class->remove_method($accessor) |
32b01180 |
476 | if (ref($method) && $method->isa('Class::MOP::Method::Attribute')); |
b51af7f9 |
477 | }; |
1d68af04 |
478 | |
b51af7f9 |
479 | sub remove_accessors { |
9ec169fe |
480 | my $self = shift; |
2367814a |
481 | # TODO: |
1d68af04 |
482 | # we really need to make sure to remove from the |
483 | # associates methods here as well. But this is |
484 | # such a slimly used method, I am not worried |
2367814a |
485 | # about it right now. |
9ec169fe |
486 | $_remove_accessor->($self->accessor(), $self->associated_class()) if $self->has_accessor(); |
487 | $_remove_accessor->($self->reader(), $self->associated_class()) if $self->has_reader(); |
488 | $_remove_accessor->($self->writer(), $self->associated_class()) if $self->has_writer(); |
489 | $_remove_accessor->($self->predicate(), $self->associated_class()) if $self->has_predicate(); |
7d28758b |
490 | $_remove_accessor->($self->clearer(), $self->associated_class()) if $self->has_clearer(); |
1d68af04 |
491 | return; |
b51af7f9 |
492 | } |
493 | |
8b978dd5 |
494 | } |
495 | |
496 | 1; |
497 | |
498 | __END__ |
499 | |
500 | =pod |
501 | |
1d68af04 |
502 | =head1 NAME |
8b978dd5 |
503 | |
504 | Class::MOP::Attribute - Attribute Meta Object |
505 | |
506 | =head1 SYNOPSIS |
1d68af04 |
507 | |
2e23f7dc |
508 | Class::MOP::Attribute->new( |
509 | foo => ( |
510 | accessor => 'foo', # dual purpose get/set accessor |
511 | predicate => 'has_foo', # predicate check for defined-ness |
512 | init_arg => '-foo', # class->new will look for a -foo key |
513 | default => 'BAR IS BAZ!' # if no -foo key is provided, use this |
514 | ) |
515 | ); |
516 | |
517 | Class::MOP::Attribute->new( |
518 | bar => ( |
519 | reader => 'bar', # getter |
520 | writer => 'set_bar', # setter |
521 | predicate => 'has_bar', # predicate check for defined-ness |
522 | init_arg => ':bar', # class->new will look for a :bar key |
523 | # no default value means it is undef |
524 | ) |
525 | ); |
8b978dd5 |
526 | |
527 | =head1 DESCRIPTION |
528 | |
2e23f7dc |
529 | The Attribute Protocol is almost entirely an invention of |
530 | C<Class::MOP>. Perl 5 does not have a consistent notion of |
531 | attributes. There are so many ways in which this is done, and very few |
532 | (if any) are easily discoverable by this module. |
552e3d24 |
533 | |
2e23f7dc |
534 | With that said, this module attempts to inject some order into this |
1d68af04 |
535 | chaos, by introducing a consistent API which can be used to create |
fe122940 |
536 | object attributes. |
552e3d24 |
537 | |
538 | =head1 METHODS |
539 | |
540 | =head2 Creation |
541 | |
542 | =over 4 |
543 | |
2e23f7dc |
544 | =item B<< Class::MOP::Attribute->new($name, ?%options) >> |
fe122940 |
545 | |
1d68af04 |
546 | An attribute must (at the very least), have a C<$name>. All other |
2e23f7dc |
547 | C<%options> are added as key-value pairs. |
fe122940 |
548 | |
2e23f7dc |
549 | =over 8 |
fe122940 |
550 | |
76187047 |
551 | =item * init_arg |
fe122940 |
552 | |
2e23f7dc |
553 | This is a string value representing the expected key in an |
554 | initialization hash. For instance, if we have an C<init_arg> value of |
555 | C<-foo>, then the following code will Just Work. |
fe122940 |
556 | |
d69fb6b3 |
557 | MyClass->meta->new_object( -foo => 'Hello There' ); |
fe122940 |
558 | |
2e23f7dc |
559 | If an init_arg is not assigned, it will automatically use the |
560 | attribute's name. If C<init_arg> is explicitly set to C<undef>, the |
561 | attribute cannot be specified during initialization. |
7b31baf4 |
562 | |
76187047 |
563 | =item * builder |
1d68af04 |
564 | |
2e23f7dc |
565 | This provides the name of a method that will be called to initialize |
566 | the attribute. This method will be called on the object after it is |
567 | constructed. It is expected to return a valid value for the attribute. |
fe122940 |
568 | |
76187047 |
569 | =item * default |
4c4a6c41 |
570 | |
2e23f7dc |
571 | This can be used to provide an explicit default for initializing the |
572 | attribute. If the default you provide is a subroutine reference, then |
573 | this reference will be called I<as a method> on the object. |
4c4a6c41 |
574 | |
2e23f7dc |
575 | If the value is a simple scalar (string or number), then it can be |
576 | just passed as is. However, if you wish to initialize it with a HASH |
577 | or ARRAY ref, then you need to wrap that inside a subroutine |
578 | reference: |
fe122940 |
579 | |
2e23f7dc |
580 | Class::MOP::Attribute->new( |
581 | 'foo' => ( |
582 | default => sub { [] }, |
583 | ) |
584 | ); |
1d68af04 |
585 | |
586 | # or ... |
587 | |
2e23f7dc |
588 | Class::MOP::Attribute->new( |
589 | 'foo' => ( |
590 | default => sub { {} }, |
591 | ) |
592 | ); |
593 | |
594 | If you wish to initialize an attribute with a subroutine reference |
595 | itself, then you need to wrap that in a subroutine as well: |
596 | |
597 | Class::MOP::Attribute->new( |
598 | 'foo' => ( |
599 | default => sub { |
600 | sub { print "Hello World" } |
601 | }, |
602 | ) |
603 | ); |
604 | |
605 | And lastly, if the value of your attribute is dependent upon some |
606 | other aspect of the instance structure, then you can take advantage of |
607 | the fact that when the C<default> value is called as a method: |
608 | |
609 | Class::MOP::Attribute->new( |
610 | 'object_identity' => ( |
611 | default => sub { Scalar::Util::refaddr( $_[0] ) }, |
612 | ) |
613 | ); |
614 | |
615 | Note that there is no guarantee that attributes are initialized in any |
616 | particular order, so you cannot rely on the value of some other |
617 | attribute when generating the default. |
fe122940 |
618 | |
76187047 |
619 | =item * initializer |
0ef07b33 |
620 | |
2e23f7dc |
621 | This option can be either a method name or a subroutine |
622 | reference. This method will be called when setting the attribute's |
623 | value in the constructor. Unlike C<default> and C<builder>, the |
624 | initializer is only called when a value is provided to the |
625 | constructor. The initializer allows you to munge this value during |
626 | object construction. |
627 | |
628 | The initializer is called as a method with three arguments. The first |
629 | is the value that was passed to the constructor. The second is a |
630 | subroutine reference that can be called to actually set the |
631 | attribute's value, and the last is the associated |
632 | C<Class::MOP::Attribute> object. |
633 | |
634 | This contrived example shows an initializer that sets the attribute to |
635 | twice the given value. |
636 | |
637 | Class::MOP::Attribute->new( |
638 | 'doubled' => ( |
639 | initializer => sub { |
ea62c8ab |
640 | my ( $self, $value, $set, $attr ) = @_; |
2e23f7dc |
641 | $set->( $value * 2 ); |
642 | }, |
643 | ) |
644 | ); |
645 | |
646 | Since an initializer can be a method name, you can easily make |
0ef07b33 |
647 | attribute initialization use the writer: |
648 | |
2e23f7dc |
649 | Class::MOP::Attribute->new( |
650 | 'some_attr' => ( |
651 | writer => 'some_attr', |
652 | initializer => 'some_attr', |
653 | ) |
654 | ); |
0ef07b33 |
655 | |
2e23f7dc |
656 | Your writer will need to examine C<@_> and determine under which |
657 | context it is being called. |
127d39a7 |
658 | |
fe122940 |
659 | =back |
660 | |
2e23f7dc |
661 | The C<accessor>, C<reader>, C<writer>, C<predicate> and C<clearer> |
662 | options all accept the same parameters. You can provide the name of |
663 | the method, in which case an appropriate default method will be |
664 | generated for you. Or instead you can also provide hash reference |
665 | containing exactly one key (the method name) and one value. The value |
666 | should be a subroutine reference, which will be installed as the |
667 | method itself. |
59e7697f |
668 | |
76187047 |
669 | =over 8 |
59e7697f |
670 | |
76187047 |
671 | =item * accessor |
59e7697f |
672 | |
2e23f7dc |
673 | An C<accessor> is a standard Perl-style read/write accessor. It will |
674 | return the value of the attribute, and if a value is passed as an |
675 | argument, it will assign that value to the attribute. |
fe122940 |
676 | |
2e23f7dc |
677 | Note that C<undef> is a legitimate value, so this will work: |
fe122940 |
678 | |
679 | $object->set_something(undef); |
680 | |
76187047 |
681 | =item * reader |
59e7697f |
682 | |
2e23f7dc |
683 | This is a basic read-only accessor. It returns the value of the |
684 | attribute. |
fe122940 |
685 | |
76187047 |
686 | =item * writer |
59e7697f |
687 | |
1d68af04 |
688 | This is a basic write accessor, it accepts a single argument, and |
2e23f7dc |
689 | assigns that value to the attribute. |
59e7697f |
690 | |
2e23f7dc |
691 | Note that C<undef> is a legitimate value, so this will work: |
59e7697f |
692 | |
2e23f7dc |
693 | $object->set_something(undef); |
fe122940 |
694 | |
76187047 |
695 | =item * predicate |
fe122940 |
696 | |
2e23f7dc |
697 | The predicate method returns a boolean indicating whether or not the |
698 | attribute has been explicitly set. |
07dca7e3 |
699 | |
2e23f7dc |
700 | Note that the predicate returns true even if the attribute was set to |
701 | a false value (C<0> or C<undef>). |
07dca7e3 |
702 | |
76187047 |
703 | =item * clearer |
7d28758b |
704 | |
2e23f7dc |
705 | This method will uninitialize the attribute. After an attribute is |
706 | cleared, its C<predicate> will return false. |
7d28758b |
707 | |
76187047 |
708 | =item * definition_context |
f8813817 |
709 | |
710 | Mostly, this exists as a hook for the benefit of Moose. |
711 | |
712 | This option should be a hash reference containing several keys which |
713 | will be used when inlining the attribute's accessors. The keys should |
714 | include C<line>, the line number where the attribute was created, and |
715 | either C<file> or C<description>. |
716 | |
717 | This information will ultimately be used when eval'ing inlined |
718 | accessor code so that error messages report a useful line and file |
719 | name. |
720 | |
59e7697f |
721 | =back |
552e3d24 |
722 | |
2e23f7dc |
723 | =item B<< $attr->clone(%options) >> |
bd4e03f9 |
724 | |
2e23f7dc |
725 | This clones the attribute. Any options you provide will override the |
726 | settings of the original attribute. You can change the name of the new |
727 | attribute by passing a C<name> key in C<%options>. |
127d39a7 |
728 | |
2e23f7dc |
729 | =back |
bd4e03f9 |
730 | |
2e23f7dc |
731 | =head2 Informational |
127d39a7 |
732 | |
2e23f7dc |
733 | These are all basic read-only accessors for the values passed into |
734 | the constructor. |
552e3d24 |
735 | |
2e23f7dc |
736 | =over 4 |
16e960bd |
737 | |
2e23f7dc |
738 | =item B<< $attr->name >> |
2367814a |
739 | |
76187047 |
740 | Returns the attribute's name. |
741 | |
2e23f7dc |
742 | =item B<< $attr->accessor >> |
2367814a |
743 | |
2e23f7dc |
744 | =item B<< $attr->reader >> |
16e960bd |
745 | |
2e23f7dc |
746 | =item B<< $attr->writer >> |
16e960bd |
747 | |
2e23f7dc |
748 | =item B<< $attr->predicate >> |
16e960bd |
749 | |
2e23f7dc |
750 | =item B<< $attr->clearer >> |
c0921932 |
751 | |
2e23f7dc |
752 | The C<accessor>, C<reader>, C<writer>, C<predicate>, and C<clearer> |
753 | methods all return exactly what was passed to the constructor, so it |
a6710c60 |
754 | can be either a string containing a method name, or a hash reference. |
c0921932 |
755 | |
2e23f7dc |
756 | =item B<< $attr->initializer >> |
16e960bd |
757 | |
a6710c60 |
758 | Returns the initializer as passed to the constructor, so this may be |
2e23f7dc |
759 | either a method name or a subroutine reference. |
16e960bd |
760 | |
2e23f7dc |
761 | =item B<< $attr->init_arg >> |
3545c727 |
762 | |
2e23f7dc |
763 | =item B<< $attr->is_default_a_coderef >> |
2367814a |
764 | |
2e23f7dc |
765 | =item B<< $attr->default($instance) >> |
3545c727 |
766 | |
2e23f7dc |
767 | The C<$instance> argument is optional. If you don't pass it, the |
768 | return value for this method is exactly what was passed to the |
769 | constructor, either a simple scalar or a subroutine reference. |
2367814a |
770 | |
2e23f7dc |
771 | If you I<do> pass an C<$instance> and the default is a subroutine |
772 | reference, then the reference is called as a method on the |
773 | C<$instance> and the generated value is returned. |
16e960bd |
774 | |
2e23f7dc |
775 | =item B<< $attr->slots >> |
552e3d24 |
776 | |
2e23f7dc |
777 | Return a list of slots required by the attribute. This is usually just |
778 | one, the name of the attribute. |
fe122940 |
779 | |
2e23f7dc |
780 | A slot is the name of the hash key used to store the attribute in an |
781 | object instance. |
552e3d24 |
782 | |
2e23f7dc |
783 | =item B<< $attr->get_read_method >> |
552e3d24 |
784 | |
2e23f7dc |
785 | =item B<< $attr->get_write_method >> |
552e3d24 |
786 | |
2e23f7dc |
787 | Returns the name of a method suitable for reading or writing the value |
788 | of the attribute in the associated class. |
552e3d24 |
789 | |
2e23f7dc |
790 | If an attribute is read- or write-only, then these methods can return |
791 | C<undef> as appropriate. |
552e3d24 |
792 | |
2e23f7dc |
793 | =item B<< $attr->has_read_method >> |
c50c603e |
794 | |
2e23f7dc |
795 | =item B<< $attr->has_write_method >> |
7d28758b |
796 | |
2e23f7dc |
797 | This returns a boolean indicating whether the attribute has a I<named> |
798 | read or write method. |
0ab65f99 |
799 | |
2e23f7dc |
800 | =item B<< $attr->get_read_method_ref >> |
552e3d24 |
801 | |
2e23f7dc |
802 | =item B<< $attr->get_write_method_ref >> |
495af518 |
803 | |
2e23f7dc |
804 | Returns the subroutine reference of a method suitable for reading or |
805 | writing the attribute's value in the associated class. These methods |
806 | always return a subroutine reference, regardless of whether or not the |
807 | attribute is read- or write-only. |
808 | |
eeff7496 |
809 | =item B<< $attr->insertion_order >> |
810 | |
811 | If this attribute has been inserted into a class, this returns a zero |
812 | based index regarding the order of insertion. |
813 | |
2e23f7dc |
814 | =back |
fe122940 |
815 | |
2e23f7dc |
816 | =head2 Informational predicates |
92d2abfa |
817 | |
2e23f7dc |
818 | These are all basic predicate methods for the values passed into C<new>. |
552e3d24 |
819 | |
2e23f7dc |
820 | =over 4 |
c57c8b10 |
821 | |
2e23f7dc |
822 | =item B<< $attr->has_accessor >> |
c57c8b10 |
823 | |
2e23f7dc |
824 | =item B<< $attr->has_reader >> |
b25109b1 |
825 | |
2e23f7dc |
826 | =item B<< $attr->has_writer >> |
b25109b1 |
827 | |
2e23f7dc |
828 | =item B<< $attr->has_predicate >> |
5da16d1b |
829 | |
2e23f7dc |
830 | =item B<< $attr->has_clearer >> |
5da16d1b |
831 | |
2e23f7dc |
832 | =item B<< $attr->has_initializer >> |
5da16d1b |
833 | |
2e23f7dc |
834 | =item B<< $attr->has_init_arg >> |
5da16d1b |
835 | |
2e23f7dc |
836 | This will be I<false> if the C<init_arg> was set to C<undef>. |
b25109b1 |
837 | |
2e23f7dc |
838 | =item B<< $attr->has_default >> |
9e517e01 |
839 | |
2e23f7dc |
840 | This will be I<false> if the C<default> was set to C<undef>, since |
841 | C<undef> is the default C<default> anyway. |
9e517e01 |
842 | |
2e23f7dc |
843 | =item B<< $attr->has_builder >> |
9e517e01 |
844 | |
eeff7496 |
845 | =item B<< $attr->has_insertion_order >> |
846 | |
847 | This will be I<false> if this attribute has not be inserted into a class |
848 | |
552e3d24 |
849 | =back |
850 | |
2e23f7dc |
851 | =head2 Value management |
552e3d24 |
852 | |
a6710c60 |
853 | These methods are basically "back doors" to the instance, and can be |
2e23f7dc |
854 | used to bypass the regular accessors, but still stay within the MOP. |
855 | |
856 | These methods are not for general use, and should only be used if you |
857 | really know what you are doing. |
fe122940 |
858 | |
552e3d24 |
859 | =over 4 |
860 | |
2e23f7dc |
861 | =item B<< $attr->initialize_instance_slot($meta_instance, $instance, $params) >> |
862 | |
863 | This method is used internally to initialize the attribute's slot in |
864 | the object C<$instance>. |
865 | |
866 | The C<$params> is a hash reference of the values passed to the object |
867 | constructor. |
868 | |
869 | It's unlikely that you'll need to call this method yourself. |
552e3d24 |
870 | |
2e23f7dc |
871 | =item B<< $attr->set_value($instance, $value) >> |
552e3d24 |
872 | |
2e23f7dc |
873 | Sets the value without going through the accessor. Note that this |
874 | works even with read-only attributes. |
552e3d24 |
875 | |
7e5efe15 |
876 | =item B<< $attr->set_raw_value($instance, $value) >> |
877 | |
878 | Sets the value with no side effects such as a trigger. |
879 | |
880 | This doesn't actually apply to Class::MOP attributes, only to subclasses. |
881 | |
2e23f7dc |
882 | =item B<< $attr->set_initial_value($instance, $value) >> |
c50c603e |
883 | |
2e23f7dc |
884 | Sets the value without going through the accessor. This method is only |
885 | called when the instance is first being initialized. |
7d28758b |
886 | |
2e23f7dc |
887 | =item B<< $attr->get_value($instance) >> |
0ab65f99 |
888 | |
2e23f7dc |
889 | Returns the value without going through the accessor. Note that this |
890 | works even with write-only accessors. |
552e3d24 |
891 | |
7e5efe15 |
892 | =item B<< $sttr->get_raw_value($instance) >> |
893 | |
894 | Returns the value without any side effects such as lazy attributes. |
895 | |
896 | Doesn't actually apply to Class::MOP attributes, only to subclasses. |
897 | |
2e23f7dc |
898 | =item B<< $attr->has_value($instance) >> |
552e3d24 |
899 | |
2e23f7dc |
900 | Return a boolean indicating whether the attribute has been set in |
901 | C<$instance>. This how the default C<predicate> method works. |
902 | |
903 | =item B<< $attr->clear_value($instance) >> |
904 | |
905 | This will clear the attribute's value in C<$instance>. This is what |
906 | the default C<clearer> calls. |
907 | |
908 | Note that this works even if the attribute does not have any |
909 | associated read, write or clear methods. |
bf731086 |
910 | |
552e3d24 |
911 | =back |
912 | |
9ec169fe |
913 | =head2 Class association |
914 | |
1d68af04 |
915 | These methods allow you to manage the attributes association with |
916 | the class that contains it. These methods should not be used |
2367814a |
917 | lightly, nor are they very magical, they are mostly used internally |
918 | and by metaclass instances. |
919 | |
9ec169fe |
920 | =over 4 |
921 | |
2e23f7dc |
922 | =item B<< $attr->associated_class >> |
923 | |
924 | This returns the C<Class::MOP::Class> with which this attribute is |
925 | associated, if any. |
926 | |
927 | =item B<< $attr->attach_to_class($metaclass) >> |
9ec169fe |
928 | |
2e23f7dc |
929 | This method stores a weakened reference to the C<$metaclass> object |
930 | internally. |
2367814a |
931 | |
2e23f7dc |
932 | This method does not remove the attribute from its old class, |
933 | nor does it create any accessors in the new class. |
9ec169fe |
934 | |
2e23f7dc |
935 | It is probably best to use the L<Class::MOP::Class> C<add_attribute> |
936 | method instead. |
2367814a |
937 | |
2e23f7dc |
938 | =item B<< $attr->detach_from_class >> |
9ec169fe |
939 | |
2e23f7dc |
940 | This method removes the associate metaclass object from the attribute |
941 | it has one. |
942 | |
943 | This method does not remove the attribute itself from the class, or |
944 | remove its accessors. |
945 | |
946 | It is probably best to use the L<Class::MOP::Class> |
947 | C<remove_attribute> method instead. |
2367814a |
948 | |
9ec169fe |
949 | =back |
950 | |
552e3d24 |
951 | =head2 Attribute Accessor generation |
952 | |
953 | =over 4 |
954 | |
2e23f7dc |
955 | =item B<< $attr->accessor_metaclass >> |
ba38bf08 |
956 | |
2e23f7dc |
957 | Accessor methods are generated using an accessor metaclass. By |
958 | default, this is L<Class::MOP::Method::Accessor>. This method returns |
2367814a |
959 | the name of the accessor metaclass that this attribute uses. |
960 | |
2e23f7dc |
961 | =item B<< $attr->associate_method($method) >> |
2367814a |
962 | |
2e23f7dc |
963 | This associates a L<Class::MOP::Method> object with the |
964 | attribute. Typically, this is called internally when an attribute |
965 | generates its accessors. |
3545c727 |
966 | |
2e23f7dc |
967 | =item B<< $attr->associated_methods >> |
3545c727 |
968 | |
2e23f7dc |
969 | This returns the list of methods which have been associated with the |
970 | attribute. |
2367814a |
971 | |
2e23f7dc |
972 | =item B<< $attr->install_accessors >> |
2eb717d5 |
973 | |
2e23f7dc |
974 | This method generates and installs code the attributes various |
975 | accessors. It is typically called from the L<Class::MOP::Class> |
976 | C<add_attribute> method. |
2eb717d5 |
977 | |
2e23f7dc |
978 | =item B<< $attr->remove_accessors >> |
2eb717d5 |
979 | |
2e23f7dc |
980 | This method removes all of the accessors associated with the |
981 | attribute. |
2eb717d5 |
982 | |
2e23f7dc |
983 | This does not currently remove methods from the list returned by |
984 | C<associated_methods>. |
2367814a |
985 | |
2eb717d5 |
986 | =back |
987 | |
988 | =head2 Introspection |
989 | |
990 | =over 4 |
552e3d24 |
991 | |
45b4c423 |
992 | =item B<< Class::MOP::Attribute->meta >> |
552e3d24 |
993 | |
2e23f7dc |
994 | This will return a L<Class::MOP::Class> instance for this class. |
fe122940 |
995 | |
2e23f7dc |
996 | It should also be noted that L<Class::MOP> will actually bootstrap |
997 | this module by installing a number of attribute meta-objects into its |
998 | metaclass. |
fe122940 |
999 | |
552e3d24 |
1000 | =back |
1001 | |
1a09d9cc |
1002 | =head1 AUTHORS |
8b978dd5 |
1003 | |
a2e85e6c |
1004 | Stevan Little E<lt>stevan@iinteractive.comE<gt> |
8b978dd5 |
1005 | |
1006 | =head1 COPYRIGHT AND LICENSE |
1007 | |
070bb6c9 |
1008 | Copyright 2006-2009 by Infinity Interactive, Inc. |
8b978dd5 |
1009 | |
1010 | L<http://www.iinteractive.com> |
1011 | |
1012 | This library is free software; you can redistribute it and/or modify |
1d68af04 |
1013 | it under the same terms as Perl itself. |
8b978dd5 |
1014 | |
16e960bd |
1015 | =cut |
1016 | |
7d28758b |
1017 | |