Commit | Line | Data |
38bf2a25 |
1 | |
2 | package Class::MOP::Instance; |
3 | |
4 | use strict; |
5 | use warnings; |
6 | |
69bdb51f |
7 | use Scalar::Util 'isweak', 'weaken', 'blessed'; |
38bf2a25 |
8 | |
38bf2a25 |
9 | use base 'Class::MOP::Object'; |
10 | |
11 | # make this not a valid method name, to avoid (most) attribute conflicts |
12 | my $RESERVED_MOP_SLOT = '<<MOP>>'; |
13 | |
14 | sub BUILDARGS { |
15 | my ($class, @args) = @_; |
16 | |
17 | if ( @args == 1 ) { |
18 | unshift @args, "associated_metaclass"; |
19 | } elsif ( @args >= 2 && blessed($args[0]) && $args[0]->isa("Class::MOP::Class") ) { |
20 | # compat mode |
21 | my ( $meta, @attrs ) = @args; |
22 | @args = ( associated_metaclass => $meta, attributes => \@attrs ); |
23 | } |
24 | |
25 | my %options = @args; |
26 | # FIXME lazy_build |
27 | $options{slots} ||= [ map { $_->slots } @{ $options{attributes} || [] } ]; |
28 | $options{slot_hash} = { map { $_ => undef } @{ $options{slots} } }; # FIXME lazy_build |
29 | |
30 | return \%options; |
31 | } |
32 | |
33 | sub new { |
34 | my $class = shift; |
35 | my $options = $class->BUILDARGS(@_); |
36 | |
37 | # FIXME replace with a proper constructor |
38 | my $instance = $class->_new(%$options); |
39 | |
40 | # FIXME weak_ref => 1, |
41 | weaken($instance->{'associated_metaclass'}); |
42 | |
43 | return $instance; |
44 | } |
45 | |
46 | sub _new { |
47 | my $class = shift; |
48 | return Class::MOP::Class->initialize($class)->new_object(@_) |
49 | if $class ne __PACKAGE__; |
50 | |
51 | my $params = @_ == 1 ? $_[0] : {@_}; |
52 | return bless { |
53 | # NOTE: |
54 | # I am not sure that it makes |
55 | # sense to pass in the meta |
56 | # The ideal would be to just |
57 | # pass in the class name, but |
58 | # that is placing too much of |
59 | # an assumption on bless(), |
60 | # which is *probably* a safe |
61 | # assumption,.. but you can |
62 | # never tell <:) |
63 | 'associated_metaclass' => $params->{associated_metaclass}, |
64 | 'attributes' => $params->{attributes}, |
65 | 'slots' => $params->{slots}, |
66 | 'slot_hash' => $params->{slot_hash}, |
67 | } => $class; |
68 | } |
69 | |
70 | sub _class_name { $_[0]->{_class_name} ||= $_[0]->associated_metaclass->name } |
71 | |
72 | sub create_instance { |
73 | my $self = shift; |
74 | bless {}, $self->_class_name; |
75 | } |
76 | |
77 | sub clone_instance { |
78 | my ($self, $instance) = @_; |
1e3716d3 |
79 | |
69bdb51f |
80 | my $clone = $self->create_instance; |
1e3716d3 |
81 | for my $attr ($self->get_all_attributes) { |
69bdb51f |
82 | next unless $attr->has_value($instance); |
83 | for my $slot ($attr->slots) { |
84 | my $val = $self->get_slot_value($instance, $slot); |
85 | $self->set_slot_value($clone, $slot, $val); |
86 | $self->weaken_slot_value($clone, $slot) |
87 | if $self->slot_value_is_weak($instance, $slot); |
88 | } |
1e3716d3 |
89 | } |
90 | |
69bdb51f |
91 | $self->_set_mop_slot($clone, $self->_get_mop_slot($instance)) |
92 | if $self->_has_mop_slot($instance); |
93 | |
1e3716d3 |
94 | return $clone; |
38bf2a25 |
95 | } |
96 | |
97 | # operations on meta instance |
98 | |
99 | sub get_all_slots { |
100 | my $self = shift; |
101 | return @{$self->{'slots'}}; |
102 | } |
103 | |
104 | sub get_all_attributes { |
105 | my $self = shift; |
106 | return @{$self->{attributes}}; |
107 | } |
108 | |
109 | sub is_valid_slot { |
110 | my ($self, $slot_name) = @_; |
111 | exists $self->{'slot_hash'}->{$slot_name}; |
112 | } |
113 | |
114 | # operations on created instances |
115 | |
116 | sub get_slot_value { |
117 | my ($self, $instance, $slot_name) = @_; |
118 | $instance->{$slot_name}; |
119 | } |
120 | |
121 | sub set_slot_value { |
122 | my ($self, $instance, $slot_name, $value) = @_; |
123 | $instance->{$slot_name} = $value; |
124 | } |
125 | |
126 | sub initialize_slot { |
127 | my ($self, $instance, $slot_name) = @_; |
128 | return; |
129 | } |
130 | |
131 | sub deinitialize_slot { |
132 | my ( $self, $instance, $slot_name ) = @_; |
133 | delete $instance->{$slot_name}; |
134 | } |
135 | |
136 | sub initialize_all_slots { |
137 | my ($self, $instance) = @_; |
138 | foreach my $slot_name ($self->get_all_slots) { |
139 | $self->initialize_slot($instance, $slot_name); |
140 | } |
141 | } |
142 | |
143 | sub deinitialize_all_slots { |
144 | my ($self, $instance) = @_; |
145 | foreach my $slot_name ($self->get_all_slots) { |
146 | $self->deinitialize_slot($instance, $slot_name); |
147 | } |
148 | } |
149 | |
150 | sub is_slot_initialized { |
151 | my ($self, $instance, $slot_name, $value) = @_; |
152 | exists $instance->{$slot_name}; |
153 | } |
154 | |
155 | sub weaken_slot_value { |
156 | my ($self, $instance, $slot_name) = @_; |
157 | weaken $instance->{$slot_name}; |
158 | } |
159 | |
69bdb51f |
160 | sub slot_value_is_weak { |
161 | my ($self, $instance, $slot_name) = @_; |
162 | isweak $instance->{$slot_name}; |
163 | } |
164 | |
38bf2a25 |
165 | sub strengthen_slot_value { |
166 | my ($self, $instance, $slot_name) = @_; |
167 | $self->set_slot_value($instance, $slot_name, $self->get_slot_value($instance, $slot_name)); |
168 | } |
169 | |
170 | sub rebless_instance_structure { |
171 | my ($self, $instance, $metaclass) = @_; |
172 | |
2c739d1a |
173 | # we use $_[1] here because of t/cmop/rebless_overload.t regressions |
174 | # on 5.8.8 |
38bf2a25 |
175 | bless $_[1], $metaclass->name; |
176 | } |
177 | |
178 | sub is_dependent_on_superclasses { |
179 | return; # for meta instances that require updates on inherited slot changes |
180 | } |
181 | |
182 | sub _get_mop_slot { |
183 | my ($self, $instance) = @_; |
184 | $self->get_slot_value($instance, $RESERVED_MOP_SLOT); |
185 | } |
186 | |
69bdb51f |
187 | sub _has_mop_slot { |
188 | my ($self, $instance) = @_; |
189 | $self->is_slot_initialized($instance, $RESERVED_MOP_SLOT); |
190 | } |
191 | |
38bf2a25 |
192 | sub _set_mop_slot { |
193 | my ($self, $instance, $value) = @_; |
194 | $self->set_slot_value($instance, $RESERVED_MOP_SLOT, $value); |
195 | } |
196 | |
197 | sub _clear_mop_slot { |
198 | my ($self, $instance) = @_; |
199 | $self->deinitialize_slot($instance, $RESERVED_MOP_SLOT); |
200 | } |
201 | |
202 | # inlinable operation snippets |
203 | |
204 | sub is_inlinable { 1 } |
205 | |
206 | sub inline_create_instance { |
207 | my ($self, $class_variable) = @_; |
208 | 'bless {} => ' . $class_variable; |
209 | } |
210 | |
211 | sub inline_slot_access { |
212 | my ($self, $instance, $slot_name) = @_; |
213 | sprintf q[%s->{"%s"}], $instance, quotemeta($slot_name); |
214 | } |
215 | |
216 | sub inline_get_is_lvalue { 1 } |
217 | |
218 | sub inline_get_slot_value { |
219 | my ($self, $instance, $slot_name) = @_; |
220 | $self->inline_slot_access($instance, $slot_name); |
221 | } |
222 | |
223 | sub inline_set_slot_value { |
224 | my ($self, $instance, $slot_name, $value) = @_; |
225 | $self->inline_slot_access($instance, $slot_name) . " = $value", |
226 | } |
227 | |
228 | sub inline_initialize_slot { |
229 | my ($self, $instance, $slot_name) = @_; |
230 | return ''; |
231 | } |
232 | |
233 | sub inline_deinitialize_slot { |
234 | my ($self, $instance, $slot_name) = @_; |
235 | "delete " . $self->inline_slot_access($instance, $slot_name); |
236 | } |
237 | sub inline_is_slot_initialized { |
238 | my ($self, $instance, $slot_name) = @_; |
239 | "exists " . $self->inline_slot_access($instance, $slot_name); |
240 | } |
241 | |
242 | sub inline_weaken_slot_value { |
243 | my ($self, $instance, $slot_name) = @_; |
244 | sprintf "Scalar::Util::weaken( %s )", $self->inline_slot_access($instance, $slot_name); |
245 | } |
246 | |
247 | sub inline_strengthen_slot_value { |
248 | my ($self, $instance, $slot_name) = @_; |
249 | $self->inline_set_slot_value($instance, $slot_name, $self->inline_slot_access($instance, $slot_name)); |
250 | } |
251 | |
252 | sub inline_rebless_instance_structure { |
253 | my ($self, $instance, $class_variable) = @_; |
254 | "bless $instance => $class_variable"; |
255 | } |
256 | |
257 | sub _inline_get_mop_slot { |
258 | my ($self, $instance) = @_; |
259 | $self->inline_get_slot_value($instance, $RESERVED_MOP_SLOT); |
260 | } |
261 | |
262 | sub _inline_set_mop_slot { |
263 | my ($self, $instance, $value) = @_; |
264 | $self->inline_set_slot_value($instance, $RESERVED_MOP_SLOT, $value); |
265 | } |
266 | |
267 | sub _inline_clear_mop_slot { |
268 | my ($self, $instance) = @_; |
269 | $self->inline_deinitialize_slot($instance, $RESERVED_MOP_SLOT); |
270 | } |
271 | |
272 | 1; |
273 | |
274 | # ABSTRACT: Instance Meta Object |
275 | |
276 | __END__ |
277 | |
278 | =pod |
279 | |
280 | =head1 DESCRIPTION |
281 | |
282 | The Instance Protocol controls the creation of object instances, and |
283 | the storage of attribute values in those instances. |
284 | |
285 | Using this API directly in your own code violates encapsulation, and |
286 | we recommend that you use the appropriate APIs in L<Class::MOP::Class> |
287 | and L<Class::MOP::Attribute> instead. Those APIs in turn call the |
288 | methods in this class as appropriate. |
289 | |
290 | This class also participates in generating inlined code by providing |
291 | snippets of code to access an object instance. |
292 | |
293 | =head1 METHODS |
294 | |
295 | =head2 Object construction |
296 | |
297 | =over 4 |
298 | |
299 | =item B<< Class::MOP::Instance->new(%options) >> |
300 | |
301 | This method creates a new meta-instance object. |
302 | |
303 | It accepts the following keys in C<%options>: |
304 | |
305 | =over 8 |
306 | |
307 | =item * associated_metaclass |
308 | |
309 | The L<Class::MOP::Class> object for which instances will be created. |
310 | |
311 | =item * attributes |
312 | |
313 | An array reference of L<Class::MOP::Attribute> objects. These are the |
314 | attributes which can be stored in each instance. |
315 | |
316 | =back |
317 | |
318 | =back |
319 | |
320 | =head2 Creating and altering instances |
321 | |
322 | =over 4 |
323 | |
324 | =item B<< $metainstance->create_instance >> |
325 | |
326 | This method returns a reference blessed into the associated |
327 | metaclass's class. |
328 | |
329 | The default is to use a hash reference. Subclasses can override this. |
330 | |
331 | =item B<< $metainstance->clone_instance($instance) >> |
332 | |
333 | Given an instance, this method creates a new object by making |
334 | I<shallow> clone of the original. |
335 | |
336 | =back |
337 | |
338 | =head2 Introspection |
339 | |
340 | =over 4 |
341 | |
342 | =item B<< $metainstance->associated_metaclass >> |
343 | |
344 | This returns the L<Class::MOP::Class> object associated with the |
345 | meta-instance object. |
346 | |
347 | =item B<< $metainstance->get_all_slots >> |
348 | |
349 | This returns a list of slot names stored in object instances. In |
350 | almost all cases, slot names correspond directly attribute names. |
351 | |
352 | =item B<< $metainstance->is_valid_slot($slot_name) >> |
353 | |
354 | This will return true if C<$slot_name> is a valid slot name. |
355 | |
356 | =item B<< $metainstance->get_all_attributes >> |
357 | |
358 | This returns a list of attributes corresponding to the attributes |
359 | passed to the constructor. |
360 | |
361 | =back |
362 | |
363 | =head2 Operations on Instance Structures |
364 | |
365 | It's important to understand that the meta-instance object is a |
366 | different entity from the actual instances it creates. For this |
367 | reason, any operations on the C<$instance_structure> always require |
368 | that the object instance be passed to the method. |
369 | |
370 | =over 4 |
371 | |
372 | =item B<< $metainstance->get_slot_value($instance_structure, $slot_name) >> |
373 | |
374 | =item B<< $metainstance->set_slot_value($instance_structure, $slot_name, $value) >> |
375 | |
376 | =item B<< $metainstance->initialize_slot($instance_structure, $slot_name) >> |
377 | |
378 | =item B<< $metainstance->deinitialize_slot($instance_structure, $slot_name) >> |
379 | |
380 | =item B<< $metainstance->initialize_all_slots($instance_structure) >> |
381 | |
382 | =item B<< $metainstance->deinitialize_all_slots($instance_structure) >> |
383 | |
384 | =item B<< $metainstance->is_slot_initialized($instance_structure, $slot_name) >> |
385 | |
386 | =item B<< $metainstance->weaken_slot_value($instance_structure, $slot_name) >> |
387 | |
09b3dc88 |
388 | =item B<< $metainstance->slot_value_is_weak($instance_structure, $slot_name) >> |
389 | |
38bf2a25 |
390 | =item B<< $metainstance->strengthen_slot_value($instance_structure, $slot_name) >> |
391 | |
392 | =item B<< $metainstance->rebless_instance_structure($instance_structure, $new_metaclass) >> |
393 | |
394 | The exact details of what each method does should be fairly obvious |
395 | from the method name. |
396 | |
397 | =back |
398 | |
399 | =head2 Inlinable Instance Operations |
400 | |
401 | =over 4 |
402 | |
403 | =item B<< $metainstance->is_inlinable >> |
404 | |
405 | This is a boolean that indicates whether or not slot access operations |
406 | can be inlined. By default it is true, but subclasses can override |
407 | this. |
408 | |
409 | =item B<< $metainstance->inline_create_instance($class_variable) >> |
410 | |
411 | This method expects a string that, I<when inlined>, will become a |
412 | class name. This would literally be something like C<'$class'>, not an |
413 | actual class name. |
414 | |
415 | It returns a snippet of code that creates a new object for the |
416 | class. This is something like C< bless {}, $class_name >. |
417 | |
418 | =item B<< $metainstance->inline_get_is_lvalue >> |
419 | |
420 | Returns whether or not C<inline_get_slot_value> is a valid lvalue. This can be |
421 | used to do extra optimizations when generating inlined methods. |
422 | |
423 | =item B<< $metainstance->inline_slot_access($instance_variable, $slot_name) >> |
424 | |
425 | =item B<< $metainstance->inline_get_slot_value($instance_variable, $slot_name) >> |
426 | |
427 | =item B<< $metainstance->inline_set_slot_value($instance_variable, $slot_name, $value) >> |
428 | |
429 | =item B<< $metainstance->inline_initialize_slot($instance_variable, $slot_name) >> |
430 | |
431 | =item B<< $metainstance->inline_deinitialize_slot($instance_variable, $slot_name) >> |
432 | |
433 | =item B<< $metainstance->inline_is_slot_initialized($instance_variable, $slot_name) >> |
434 | |
435 | =item B<< $metainstance->inline_weaken_slot_value($instance_variable, $slot_name) >> |
436 | |
437 | =item B<< $metainstance->inline_strengthen_slot_value($instance_variable, $slot_name) >> |
438 | |
439 | These methods all expect two arguments. The first is the name of a |
440 | variable, than when inlined, will represent the object |
441 | instance. Typically this will be a literal string like C<'$_[0]'>. |
442 | |
443 | The second argument is a slot name. |
444 | |
445 | The method returns a snippet of code that, when inlined, performs some |
446 | operation on the instance. |
447 | |
448 | =item B<< $metainstance->inline_rebless_instance_structure($instance_variable, $class_variable) >> |
449 | |
450 | This takes the name of a variable that will, when inlined, represent the object |
451 | instance, and the name of a variable that will represent the class to rebless |
452 | into, and returns code to rebless an instance into a class. |
453 | |
454 | =back |
455 | |
456 | =head2 Introspection |
457 | |
458 | =over 4 |
459 | |
460 | =item B<< Class::MOP::Instance->meta >> |
461 | |
462 | This will return a L<Class::MOP::Class> instance for this class. |
463 | |
464 | It should also be noted that L<Class::MOP> will actually bootstrap |
465 | this module by installing a number of attribute meta-objects into its |
466 | metaclass. |
467 | |
468 | =back |
469 | |
470 | =cut |
471 | |