Commit | Line | Data |
38bf2a25 |
1 | |
2 | package Class::MOP; |
3 | |
4 | use strict; |
5 | use warnings; |
6 | |
7 | use 5.008; |
8 | |
9 | use MRO::Compat; |
10 | |
11 | use Carp 'confess'; |
2f41724d |
12 | use Class::Load (); |
38bf2a25 |
13 | use Scalar::Util 'weaken', 'isweak', 'reftype', 'blessed'; |
14 | use Data::OptList; |
15 | use Try::Tiny; |
16 | |
17 | use Class::MOP::Mixin::AttributeCore; |
18 | use Class::MOP::Mixin::HasAttributes; |
19 | use Class::MOP::Mixin::HasMethods; |
20 | use Class::MOP::Class; |
21 | use Class::MOP::Attribute; |
22 | use Class::MOP::Method; |
23 | |
24 | BEGIN { |
25 | *IS_RUNNING_ON_5_10 = ($] < 5.009_005) |
26 | ? sub () { 0 } |
27 | : sub () { 1 }; |
28 | |
29 | # this is either part of core or set up appropriately by MRO::Compat |
30 | *check_package_cache_flag = \&mro::get_pkg_gen; |
31 | } |
32 | |
38bf2a25 |
33 | XSLoader::load( |
34 | 'Moose', |
202b6e57 |
35 | $Class::MOP::{VERSION} ? ${ $Class::MOP::{VERSION} } : () |
38bf2a25 |
36 | ); |
37 | |
38 | { |
39 | # Metaclasses are singletons, so we cache them here. |
40 | # there is no need to worry about destruction though |
41 | # because they should die only when the program dies. |
42 | # After all, do package definitions even get reaped? |
43 | # Anonymous classes manage their own destruction. |
44 | my %METAS; |
45 | |
46 | sub get_all_metaclasses { %METAS } |
47 | sub get_all_metaclass_instances { values %METAS } |
48 | sub get_all_metaclass_names { keys %METAS } |
49 | sub get_metaclass_by_name { $METAS{$_[0]} } |
50 | sub store_metaclass_by_name { $METAS{$_[0]} = $_[1] } |
51 | sub weaken_metaclass { weaken($METAS{$_[0]}) } |
52 | sub metaclass_is_weak { isweak($METAS{$_[0]}) } |
53 | sub does_metaclass_exist { exists $METAS{$_[0]} && defined $METAS{$_[0]} } |
54 | sub remove_metaclass_by_name { delete $METAS{$_[0]}; return } |
55 | |
56 | # This handles instances as well as class names |
57 | sub class_of { |
58 | return unless defined $_[0]; |
59 | my $class = blessed($_[0]) || $_[0]; |
60 | return $METAS{$class}; |
61 | } |
62 | |
63 | # NOTE: |
64 | # We only cache metaclasses, meaning instances of |
65 | # Class::MOP::Class. We do not cache instance of |
66 | # Class::MOP::Package or Class::MOP::Module. Mostly |
67 | # because I don't yet see a good reason to do so. |
68 | } |
69 | |
2f41724d |
70 | sub load_class { |
2f41724d |
71 | goto &Class::Load::load_class; |
38bf2a25 |
72 | } |
73 | |
74 | sub load_first_existing_class { |
2f41724d |
75 | goto &Class::Load::load_first_existing_class; |
38bf2a25 |
76 | } |
77 | |
2f41724d |
78 | sub is_class_loaded { |
2f41724d |
79 | goto &Class::Load::is_class_loaded; |
38bf2a25 |
80 | } |
81 | |
dc2b7cc8 |
82 | sub _definition_context { |
83 | my %context; |
84 | @context{qw(package file line)} = caller(1); |
85 | |
86 | return ( |
87 | definition_context => \%context, |
88 | ); |
89 | } |
90 | |
38bf2a25 |
91 | ## ---------------------------------------------------------------------------- |
92 | ## Setting up our environment ... |
93 | ## ---------------------------------------------------------------------------- |
94 | ## Class::MOP needs to have a few things in the global perl environment so |
95 | ## that it can operate effectively. Those things are done here. |
96 | ## ---------------------------------------------------------------------------- |
97 | |
98 | # ... nothing yet actually ;) |
99 | |
100 | ## ---------------------------------------------------------------------------- |
101 | ## Bootstrapping |
102 | ## ---------------------------------------------------------------------------- |
103 | ## The code below here is to bootstrap our MOP with itself. This is also |
104 | ## sometimes called "tying the knot". By doing this, we make it much easier |
105 | ## to extend the MOP through subclassing and such since now you can use the |
106 | ## MOP itself to extend itself. |
107 | ## |
108 | ## Yes, I know, thats weird and insane, but it's a good thing, trust me :) |
109 | ## ---------------------------------------------------------------------------- |
110 | |
111 | # We need to add in the meta-attributes here so that |
112 | # any subclass of Class::MOP::* will be able to |
113 | # inherit them using _construct_instance |
114 | |
115 | ## -------------------------------------------------------- |
116 | ## Class::MOP::Mixin::HasMethods |
117 | |
118 | Class::MOP::Mixin::HasMethods->meta->add_attribute( |
119 | Class::MOP::Attribute->new('_methods' => ( |
120 | reader => { |
121 | # NOTE: |
122 | # we just alias the original method |
123 | # rather than re-produce it here |
124 | '_method_map' => \&Class::MOP::Mixin::HasMethods::_method_map |
125 | }, |
dc2b7cc8 |
126 | default => sub { {} }, |
127 | _definition_context(), |
38bf2a25 |
128 | )) |
129 | ); |
130 | |
131 | Class::MOP::Mixin::HasMethods->meta->add_attribute( |
132 | Class::MOP::Attribute->new('method_metaclass' => ( |
133 | reader => { |
134 | # NOTE: |
135 | # we just alias the original method |
136 | # rather than re-produce it here |
137 | 'method_metaclass' => \&Class::MOP::Mixin::HasMethods::method_metaclass |
138 | }, |
139 | default => 'Class::MOP::Method', |
dc2b7cc8 |
140 | _definition_context(), |
38bf2a25 |
141 | )) |
142 | ); |
143 | |
144 | Class::MOP::Mixin::HasMethods->meta->add_attribute( |
145 | Class::MOP::Attribute->new('wrapped_method_metaclass' => ( |
146 | reader => { |
147 | # NOTE: |
148 | # we just alias the original method |
149 | # rather than re-produce it here |
150 | 'wrapped_method_metaclass' => \&Class::MOP::Mixin::HasMethods::wrapped_method_metaclass |
151 | }, |
152 | default => 'Class::MOP::Method::Wrapped', |
dc2b7cc8 |
153 | _definition_context(), |
38bf2a25 |
154 | )) |
155 | ); |
156 | |
157 | ## -------------------------------------------------------- |
158 | ## Class::MOP::Mixin::HasMethods |
159 | |
160 | Class::MOP::Mixin::HasAttributes->meta->add_attribute( |
161 | Class::MOP::Attribute->new('attributes' => ( |
162 | reader => { |
163 | # NOTE: we need to do this in order |
164 | # for the instance meta-object to |
165 | # not fall into meta-circular death |
166 | # |
167 | # we just alias the original method |
168 | # rather than re-produce it here |
169 | '_attribute_map' => \&Class::MOP::Mixin::HasAttributes::_attribute_map |
170 | }, |
dc2b7cc8 |
171 | default => sub { {} }, |
172 | _definition_context(), |
38bf2a25 |
173 | )) |
174 | ); |
175 | |
176 | Class::MOP::Mixin::HasAttributes->meta->add_attribute( |
177 | Class::MOP::Attribute->new('attribute_metaclass' => ( |
178 | reader => { |
179 | # NOTE: |
180 | # we just alias the original method |
181 | # rather than re-produce it here |
182 | 'attribute_metaclass' => \&Class::MOP::Mixin::HasAttributes::attribute_metaclass |
183 | }, |
184 | default => 'Class::MOP::Attribute', |
dc2b7cc8 |
185 | _definition_context(), |
38bf2a25 |
186 | )) |
187 | ); |
188 | |
189 | ## -------------------------------------------------------- |
190 | ## Class::MOP::Package |
191 | |
192 | Class::MOP::Package->meta->add_attribute( |
193 | Class::MOP::Attribute->new('package' => ( |
194 | reader => { |
195 | # NOTE: we need to do this in order |
196 | # for the instance meta-object to |
197 | # not fall into meta-circular death |
198 | # |
199 | # we just alias the original method |
200 | # rather than re-produce it here |
201 | 'name' => \&Class::MOP::Package::name |
202 | }, |
dc2b7cc8 |
203 | _definition_context(), |
38bf2a25 |
204 | )) |
205 | ); |
206 | |
207 | Class::MOP::Package->meta->add_attribute( |
208 | Class::MOP::Attribute->new('namespace' => ( |
209 | reader => { |
210 | # NOTE: |
211 | # we just alias the original method |
212 | # rather than re-produce it here |
213 | 'namespace' => \&Class::MOP::Package::namespace |
214 | }, |
215 | init_arg => undef, |
dc2b7cc8 |
216 | default => sub { \undef }, |
217 | _definition_context(), |
38bf2a25 |
218 | )) |
219 | ); |
220 | |
221 | ## -------------------------------------------------------- |
222 | ## Class::MOP::Module |
223 | |
224 | # NOTE: |
225 | # yeah this is kind of stretching things a bit, |
226 | # but truthfully the version should be an attribute |
227 | # of the Module, the weirdness comes from having to |
228 | # stick to Perl 5 convention and store it in the |
229 | # $VERSION package variable. Basically if you just |
230 | # squint at it, it will look how you want it to look. |
231 | # Either as a package variable, or as a attribute of |
232 | # the metaclass, isn't abstraction great :) |
233 | |
234 | Class::MOP::Module->meta->add_attribute( |
235 | Class::MOP::Attribute->new('version' => ( |
236 | reader => { |
237 | # NOTE: |
238 | # we just alias the original method |
239 | # rather than re-produce it here |
240 | 'version' => \&Class::MOP::Module::version |
241 | }, |
242 | init_arg => undef, |
dc2b7cc8 |
243 | default => sub { \undef }, |
244 | _definition_context(), |
38bf2a25 |
245 | )) |
246 | ); |
247 | |
248 | # NOTE: |
249 | # By following the same conventions as version here, |
250 | # we are opening up the possibility that people can |
251 | # use the $AUTHORITY in non-Class::MOP modules as |
252 | # well. |
253 | |
254 | Class::MOP::Module->meta->add_attribute( |
255 | Class::MOP::Attribute->new('authority' => ( |
256 | reader => { |
257 | # NOTE: |
258 | # we just alias the original method |
259 | # rather than re-produce it here |
260 | 'authority' => \&Class::MOP::Module::authority |
261 | }, |
262 | init_arg => undef, |
dc2b7cc8 |
263 | default => sub { \undef }, |
264 | _definition_context(), |
38bf2a25 |
265 | )) |
266 | ); |
267 | |
268 | ## -------------------------------------------------------- |
269 | ## Class::MOP::Class |
270 | |
271 | Class::MOP::Class->meta->add_attribute( |
272 | Class::MOP::Attribute->new('superclasses' => ( |
273 | accessor => { |
274 | # NOTE: |
275 | # we just alias the original method |
276 | # rather than re-produce it here |
277 | 'superclasses' => \&Class::MOP::Class::superclasses |
278 | }, |
279 | init_arg => undef, |
dc2b7cc8 |
280 | default => sub { \undef }, |
281 | _definition_context(), |
38bf2a25 |
282 | )) |
283 | ); |
284 | |
285 | Class::MOP::Class->meta->add_attribute( |
286 | Class::MOP::Attribute->new('instance_metaclass' => ( |
287 | reader => { |
288 | # NOTE: we need to do this in order |
289 | # for the instance meta-object to |
290 | # not fall into meta-circular death |
291 | # |
292 | # we just alias the original method |
293 | # rather than re-produce it here |
294 | 'instance_metaclass' => \&Class::MOP::Class::instance_metaclass |
295 | }, |
296 | default => 'Class::MOP::Instance', |
dc2b7cc8 |
297 | _definition_context(), |
38bf2a25 |
298 | )) |
299 | ); |
300 | |
301 | Class::MOP::Class->meta->add_attribute( |
302 | Class::MOP::Attribute->new('immutable_trait' => ( |
303 | reader => { |
304 | 'immutable_trait' => \&Class::MOP::Class::immutable_trait |
305 | }, |
306 | default => "Class::MOP::Class::Immutable::Trait", |
dc2b7cc8 |
307 | _definition_context(), |
38bf2a25 |
308 | )) |
309 | ); |
310 | |
311 | Class::MOP::Class->meta->add_attribute( |
312 | Class::MOP::Attribute->new('constructor_name' => ( |
313 | reader => { |
314 | 'constructor_name' => \&Class::MOP::Class::constructor_name, |
315 | }, |
316 | default => "new", |
dc2b7cc8 |
317 | _definition_context(), |
38bf2a25 |
318 | )) |
319 | ); |
320 | |
321 | Class::MOP::Class->meta->add_attribute( |
322 | Class::MOP::Attribute->new('constructor_class' => ( |
323 | reader => { |
324 | 'constructor_class' => \&Class::MOP::Class::constructor_class, |
325 | }, |
326 | default => "Class::MOP::Method::Constructor", |
dc2b7cc8 |
327 | _definition_context(), |
38bf2a25 |
328 | )) |
329 | ); |
330 | |
331 | |
332 | Class::MOP::Class->meta->add_attribute( |
333 | Class::MOP::Attribute->new('destructor_class' => ( |
334 | reader => { |
335 | 'destructor_class' => \&Class::MOP::Class::destructor_class, |
336 | }, |
dc2b7cc8 |
337 | _definition_context(), |
38bf2a25 |
338 | )) |
339 | ); |
340 | |
341 | # NOTE: |
342 | # we don't actually need to tie the knot with |
343 | # Class::MOP::Class here, it is actually handled |
344 | # within Class::MOP::Class itself in the |
345 | # _construct_class_instance method. |
346 | |
347 | ## -------------------------------------------------------- |
348 | ## Class::MOP::Mixin::AttributeCore |
349 | Class::MOP::Mixin::AttributeCore->meta->add_attribute( |
350 | Class::MOP::Attribute->new('name' => ( |
351 | reader => { |
352 | # NOTE: we need to do this in order |
353 | # for the instance meta-object to |
354 | # not fall into meta-circular death |
355 | # |
356 | # we just alias the original method |
357 | # rather than re-produce it here |
358 | 'name' => \&Class::MOP::Mixin::AttributeCore::name |
dc2b7cc8 |
359 | }, |
360 | _definition_context(), |
38bf2a25 |
361 | )) |
362 | ); |
363 | |
364 | Class::MOP::Mixin::AttributeCore->meta->add_attribute( |
365 | Class::MOP::Attribute->new('accessor' => ( |
366 | reader => { 'accessor' => \&Class::MOP::Mixin::AttributeCore::accessor }, |
367 | predicate => { 'has_accessor' => \&Class::MOP::Mixin::AttributeCore::has_accessor }, |
dc2b7cc8 |
368 | _definition_context(), |
38bf2a25 |
369 | )) |
370 | ); |
371 | |
372 | Class::MOP::Mixin::AttributeCore->meta->add_attribute( |
373 | Class::MOP::Attribute->new('reader' => ( |
374 | reader => { 'reader' => \&Class::MOP::Mixin::AttributeCore::reader }, |
375 | predicate => { 'has_reader' => \&Class::MOP::Mixin::AttributeCore::has_reader }, |
dc2b7cc8 |
376 | _definition_context(), |
38bf2a25 |
377 | )) |
378 | ); |
379 | |
380 | Class::MOP::Mixin::AttributeCore->meta->add_attribute( |
381 | Class::MOP::Attribute->new('initializer' => ( |
382 | reader => { 'initializer' => \&Class::MOP::Mixin::AttributeCore::initializer }, |
383 | predicate => { 'has_initializer' => \&Class::MOP::Mixin::AttributeCore::has_initializer }, |
dc2b7cc8 |
384 | _definition_context(), |
38bf2a25 |
385 | )) |
386 | ); |
387 | |
388 | Class::MOP::Mixin::AttributeCore->meta->add_attribute( |
389 | Class::MOP::Attribute->new('definition_context' => ( |
390 | reader => { 'definition_context' => \&Class::MOP::Mixin::AttributeCore::definition_context }, |
dc2b7cc8 |
391 | _definition_context(), |
38bf2a25 |
392 | )) |
393 | ); |
394 | |
395 | Class::MOP::Mixin::AttributeCore->meta->add_attribute( |
396 | Class::MOP::Attribute->new('writer' => ( |
397 | reader => { 'writer' => \&Class::MOP::Mixin::AttributeCore::writer }, |
398 | predicate => { 'has_writer' => \&Class::MOP::Mixin::AttributeCore::has_writer }, |
dc2b7cc8 |
399 | _definition_context(), |
38bf2a25 |
400 | )) |
401 | ); |
402 | |
403 | Class::MOP::Mixin::AttributeCore->meta->add_attribute( |
404 | Class::MOP::Attribute->new('predicate' => ( |
405 | reader => { 'predicate' => \&Class::MOP::Mixin::AttributeCore::predicate }, |
406 | predicate => { 'has_predicate' => \&Class::MOP::Mixin::AttributeCore::has_predicate }, |
dc2b7cc8 |
407 | _definition_context(), |
38bf2a25 |
408 | )) |
409 | ); |
410 | |
411 | Class::MOP::Mixin::AttributeCore->meta->add_attribute( |
412 | Class::MOP::Attribute->new('clearer' => ( |
413 | reader => { 'clearer' => \&Class::MOP::Mixin::AttributeCore::clearer }, |
414 | predicate => { 'has_clearer' => \&Class::MOP::Mixin::AttributeCore::has_clearer }, |
dc2b7cc8 |
415 | _definition_context(), |
38bf2a25 |
416 | )) |
417 | ); |
418 | |
419 | Class::MOP::Mixin::AttributeCore->meta->add_attribute( |
420 | Class::MOP::Attribute->new('builder' => ( |
421 | reader => { 'builder' => \&Class::MOP::Mixin::AttributeCore::builder }, |
422 | predicate => { 'has_builder' => \&Class::MOP::Mixin::AttributeCore::has_builder }, |
dc2b7cc8 |
423 | _definition_context(), |
38bf2a25 |
424 | )) |
425 | ); |
426 | |
427 | Class::MOP::Mixin::AttributeCore->meta->add_attribute( |
428 | Class::MOP::Attribute->new('init_arg' => ( |
429 | reader => { 'init_arg' => \&Class::MOP::Mixin::AttributeCore::init_arg }, |
430 | predicate => { 'has_init_arg' => \&Class::MOP::Mixin::AttributeCore::has_init_arg }, |
dc2b7cc8 |
431 | _definition_context(), |
38bf2a25 |
432 | )) |
433 | ); |
434 | |
435 | Class::MOP::Mixin::AttributeCore->meta->add_attribute( |
436 | Class::MOP::Attribute->new('default' => ( |
437 | # default has a custom 'reader' method ... |
438 | predicate => { 'has_default' => \&Class::MOP::Mixin::AttributeCore::has_default }, |
dc2b7cc8 |
439 | _definition_context(), |
38bf2a25 |
440 | )) |
441 | ); |
442 | |
443 | Class::MOP::Mixin::AttributeCore->meta->add_attribute( |
444 | Class::MOP::Attribute->new('insertion_order' => ( |
445 | reader => { 'insertion_order' => \&Class::MOP::Mixin::AttributeCore::insertion_order }, |
446 | writer => { '_set_insertion_order' => \&Class::MOP::Mixin::AttributeCore::_set_insertion_order }, |
447 | predicate => { 'has_insertion_order' => \&Class::MOP::Mixin::AttributeCore::has_insertion_order }, |
dc2b7cc8 |
448 | _definition_context(), |
38bf2a25 |
449 | )) |
450 | ); |
451 | |
452 | ## -------------------------------------------------------- |
453 | ## Class::MOP::Attribute |
454 | Class::MOP::Attribute->meta->add_attribute( |
455 | Class::MOP::Attribute->new('associated_class' => ( |
456 | reader => { |
457 | # NOTE: we need to do this in order |
458 | # for the instance meta-object to |
459 | # not fall into meta-circular death |
460 | # |
461 | # we just alias the original method |
462 | # rather than re-produce it here |
463 | 'associated_class' => \&Class::MOP::Attribute::associated_class |
dc2b7cc8 |
464 | }, |
465 | _definition_context(), |
38bf2a25 |
466 | )) |
467 | ); |
468 | |
469 | Class::MOP::Attribute->meta->add_attribute( |
470 | Class::MOP::Attribute->new('associated_methods' => ( |
471 | reader => { 'associated_methods' => \&Class::MOP::Attribute::associated_methods }, |
dc2b7cc8 |
472 | default => sub { [] }, |
473 | _definition_context(), |
38bf2a25 |
474 | )) |
475 | ); |
476 | |
477 | Class::MOP::Attribute->meta->add_method('clone' => sub { |
478 | my $self = shift; |
479 | $self->meta->clone_object($self, @_); |
480 | }); |
481 | |
482 | ## -------------------------------------------------------- |
483 | ## Class::MOP::Method |
484 | Class::MOP::Method->meta->add_attribute( |
485 | Class::MOP::Attribute->new('body' => ( |
486 | reader => { 'body' => \&Class::MOP::Method::body }, |
dc2b7cc8 |
487 | _definition_context(), |
38bf2a25 |
488 | )) |
489 | ); |
490 | |
491 | Class::MOP::Method->meta->add_attribute( |
492 | Class::MOP::Attribute->new('associated_metaclass' => ( |
493 | reader => { 'associated_metaclass' => \&Class::MOP::Method::associated_metaclass }, |
dc2b7cc8 |
494 | _definition_context(), |
38bf2a25 |
495 | )) |
496 | ); |
497 | |
498 | Class::MOP::Method->meta->add_attribute( |
499 | Class::MOP::Attribute->new('package_name' => ( |
500 | reader => { 'package_name' => \&Class::MOP::Method::package_name }, |
dc2b7cc8 |
501 | _definition_context(), |
38bf2a25 |
502 | )) |
503 | ); |
504 | |
505 | Class::MOP::Method->meta->add_attribute( |
506 | Class::MOP::Attribute->new('name' => ( |
507 | reader => { 'name' => \&Class::MOP::Method::name }, |
dc2b7cc8 |
508 | _definition_context(), |
38bf2a25 |
509 | )) |
510 | ); |
511 | |
512 | Class::MOP::Method->meta->add_attribute( |
513 | Class::MOP::Attribute->new('original_method' => ( |
514 | reader => { 'original_method' => \&Class::MOP::Method::original_method }, |
515 | writer => { '_set_original_method' => \&Class::MOP::Method::_set_original_method }, |
dc2b7cc8 |
516 | _definition_context(), |
38bf2a25 |
517 | )) |
518 | ); |
519 | |
520 | ## -------------------------------------------------------- |
521 | ## Class::MOP::Method::Wrapped |
522 | |
523 | # NOTE: |
524 | # the way this item is initialized, this |
525 | # really does not follow the standard |
526 | # practices of attributes, but we put |
527 | # it here for completeness |
528 | Class::MOP::Method::Wrapped->meta->add_attribute( |
dc2b7cc8 |
529 | Class::MOP::Attribute->new('modifier_table' => ( |
530 | _definition_context(), |
531 | )) |
38bf2a25 |
532 | ); |
533 | |
534 | ## -------------------------------------------------------- |
535 | ## Class::MOP::Method::Generated |
536 | |
537 | Class::MOP::Method::Generated->meta->add_attribute( |
538 | Class::MOP::Attribute->new('is_inline' => ( |
539 | reader => { 'is_inline' => \&Class::MOP::Method::Generated::is_inline }, |
dc2b7cc8 |
540 | default => 0, |
541 | _definition_context(), |
38bf2a25 |
542 | )) |
543 | ); |
544 | |
545 | Class::MOP::Method::Generated->meta->add_attribute( |
546 | Class::MOP::Attribute->new('definition_context' => ( |
547 | reader => { 'definition_context' => \&Class::MOP::Method::Generated::definition_context }, |
dc2b7cc8 |
548 | _definition_context(), |
38bf2a25 |
549 | )) |
550 | ); |
551 | |
552 | |
553 | ## -------------------------------------------------------- |
554 | ## Class::MOP::Method::Inlined |
555 | |
556 | Class::MOP::Method::Inlined->meta->add_attribute( |
557 | Class::MOP::Attribute->new('_expected_method_class' => ( |
558 | reader => { '_expected_method_class' => \&Class::MOP::Method::Inlined::_expected_method_class }, |
dc2b7cc8 |
559 | _definition_context(), |
38bf2a25 |
560 | )) |
561 | ); |
562 | |
563 | ## -------------------------------------------------------- |
564 | ## Class::MOP::Method::Accessor |
565 | |
566 | Class::MOP::Method::Accessor->meta->add_attribute( |
567 | Class::MOP::Attribute->new('attribute' => ( |
568 | reader => { |
569 | 'associated_attribute' => \&Class::MOP::Method::Accessor::associated_attribute |
570 | }, |
dc2b7cc8 |
571 | _definition_context(), |
38bf2a25 |
572 | )) |
573 | ); |
574 | |
575 | Class::MOP::Method::Accessor->meta->add_attribute( |
576 | Class::MOP::Attribute->new('accessor_type' => ( |
577 | reader => { 'accessor_type' => \&Class::MOP::Method::Accessor::accessor_type }, |
dc2b7cc8 |
578 | _definition_context(), |
38bf2a25 |
579 | )) |
580 | ); |
581 | |
582 | ## -------------------------------------------------------- |
583 | ## Class::MOP::Method::Constructor |
584 | |
585 | Class::MOP::Method::Constructor->meta->add_attribute( |
586 | Class::MOP::Attribute->new('options' => ( |
587 | reader => { |
588 | 'options' => \&Class::MOP::Method::Constructor::options |
589 | }, |
dc2b7cc8 |
590 | default => sub { +{} }, |
591 | _definition_context(), |
38bf2a25 |
592 | )) |
593 | ); |
594 | |
595 | Class::MOP::Method::Constructor->meta->add_attribute( |
596 | Class::MOP::Attribute->new('associated_metaclass' => ( |
597 | init_arg => "metaclass", # FIXME alias and rename |
598 | reader => { |
599 | 'associated_metaclass' => \&Class::MOP::Method::Constructor::associated_metaclass |
600 | }, |
dc2b7cc8 |
601 | _definition_context(), |
38bf2a25 |
602 | )) |
603 | ); |
604 | |
605 | ## -------------------------------------------------------- |
606 | ## Class::MOP::Instance |
607 | |
608 | # NOTE: |
609 | # these don't yet do much of anything, but are just |
610 | # included for completeness |
611 | |
612 | Class::MOP::Instance->meta->add_attribute( |
613 | Class::MOP::Attribute->new('associated_metaclass', |
614 | reader => { associated_metaclass => \&Class::MOP::Instance::associated_metaclass }, |
dc2b7cc8 |
615 | _definition_context(), |
38bf2a25 |
616 | ), |
617 | ); |
618 | |
619 | Class::MOP::Instance->meta->add_attribute( |
620 | Class::MOP::Attribute->new('_class_name', |
621 | init_arg => undef, |
622 | reader => { _class_name => \&Class::MOP::Instance::_class_name }, |
623 | #lazy => 1, # not yet supported by Class::MOP but out our version does it anyway |
624 | #default => sub { $_[0]->associated_metaclass->name }, |
dc2b7cc8 |
625 | _definition_context(), |
38bf2a25 |
626 | ), |
627 | ); |
628 | |
629 | Class::MOP::Instance->meta->add_attribute( |
630 | Class::MOP::Attribute->new('attributes', |
631 | reader => { attributes => \&Class::MOP::Instance::get_all_attributes }, |
dc2b7cc8 |
632 | _definition_context(), |
38bf2a25 |
633 | ), |
634 | ); |
635 | |
636 | Class::MOP::Instance->meta->add_attribute( |
637 | Class::MOP::Attribute->new('slots', |
638 | reader => { slots => \&Class::MOP::Instance::slots }, |
dc2b7cc8 |
639 | _definition_context(), |
38bf2a25 |
640 | ), |
641 | ); |
642 | |
643 | Class::MOP::Instance->meta->add_attribute( |
644 | Class::MOP::Attribute->new('slot_hash', |
645 | reader => { slot_hash => \&Class::MOP::Instance::slot_hash }, |
dc2b7cc8 |
646 | _definition_context(), |
38bf2a25 |
647 | ), |
648 | ); |
649 | |
650 | ## -------------------------------------------------------- |
651 | ## Class::MOP::Object |
652 | |
653 | # need to replace the meta method there with a real meta method object |
654 | Class::MOP::Object->meta->_add_meta_method('meta'); |
655 | |
656 | ## -------------------------------------------------------- |
657 | ## Class::MOP::Mixin |
658 | |
659 | # need to replace the meta method there with a real meta method object |
660 | Class::MOP::Mixin->meta->_add_meta_method('meta'); |
661 | |
662 | require Class::MOP::Deprecated unless our $no_deprecated; |
663 | |
664 | # we need the meta instance of the meta instance to be created now, in order |
665 | # for the constructor to be able to use it |
666 | Class::MOP::Instance->meta->get_meta_instance; |
667 | |
668 | # pretend the add_method never happenned. it hasn't yet affected anything |
669 | undef Class::MOP::Instance->meta->{_package_cache_flag}; |
670 | |
671 | ## -------------------------------------------------------- |
672 | ## Now close all the Class::MOP::* classes |
673 | |
674 | # NOTE: we don't need to inline the the accessors this only lengthens |
675 | # the compile time of the MOP, and gives us no actual benefits. |
676 | |
677 | $_->meta->make_immutable( |
678 | inline_constructor => 0, |
679 | constructor_name => "_new", |
680 | inline_accessors => 0, |
681 | ) for qw/ |
682 | Class::MOP::Package |
683 | Class::MOP::Module |
684 | Class::MOP::Class |
685 | |
686 | Class::MOP::Attribute |
687 | Class::MOP::Method |
688 | Class::MOP::Instance |
689 | |
690 | Class::MOP::Object |
691 | |
692 | Class::MOP::Method::Generated |
693 | Class::MOP::Method::Inlined |
694 | |
695 | Class::MOP::Method::Accessor |
696 | Class::MOP::Method::Constructor |
697 | Class::MOP::Method::Wrapped |
698 | |
699 | Class::MOP::Method::Meta |
700 | /; |
701 | |
702 | $_->meta->make_immutable( |
703 | inline_constructor => 0, |
704 | constructor_name => undef, |
705 | inline_accessors => 0, |
706 | ) for qw/ |
707 | Class::MOP::Mixin |
708 | Class::MOP::Mixin::AttributeCore |
709 | Class::MOP::Mixin::HasAttributes |
710 | Class::MOP::Mixin::HasMethods |
711 | /; |
712 | |
713 | 1; |
714 | |
715 | # ABSTRACT: A Meta Object Protocol for Perl 5 |
716 | |
717 | __END__ |
718 | |
719 | =pod |
720 | |
721 | =head1 DESCRIPTION |
722 | |
723 | This module is a fully functioning meta object protocol for the |
724 | Perl 5 object system. It makes no attempt to change the behavior or |
725 | characteristics of the Perl 5 object system, only to create a |
726 | protocol for its manipulation and introspection. |
727 | |
728 | That said, it does attempt to create the tools for building a rich set |
729 | of extensions to the Perl 5 object system. Every attempt has been made |
730 | to abide by the spirit of the Perl 5 object system that we all know |
731 | and love. |
732 | |
733 | This documentation is sparse on conceptual details. We suggest looking |
734 | at the items listed in the L<SEE ALSO> section for more |
735 | information. In particular the book "The Art of the Meta Object |
736 | Protocol" was very influential in the development of this system. |
737 | |
738 | =head2 What is a Meta Object Protocol? |
739 | |
740 | A meta object protocol is an API to an object system. |
741 | |
742 | To be more specific, it abstracts the components of an object system |
743 | (classes, object, methods, object attributes, etc.). These |
744 | abstractions can then be used to inspect and manipulate the object |
745 | system which they describe. |
746 | |
747 | It can be said that there are two MOPs for any object system; the |
748 | implicit MOP and the explicit MOP. The implicit MOP handles things |
749 | like method dispatch or inheritance, which happen automatically as |
750 | part of how the object system works. The explicit MOP typically |
751 | handles the introspection/reflection features of the object system. |
752 | |
753 | All object systems have implicit MOPs. Without one, they would not |
754 | work. Explicit MOPs are much less common, and depending on the |
755 | language can vary from restrictive (Reflection in Java or C#) to wide |
756 | open (CLOS is a perfect example). |
757 | |
758 | =head2 Yet Another Class Builder! Why? |
759 | |
760 | This is B<not> a class builder so much as a I<class builder |
761 | B<builder>>. The intent is that an end user will not use this module |
762 | directly, but instead this module is used by module authors to build |
763 | extensions and features onto the Perl 5 object system. |
764 | |
765 | This system is used by L<Moose>, which supplies a powerful class |
766 | builder system built entirely on top of C<Class::MOP>. |
767 | |
768 | =head2 Who is this module for? |
769 | |
770 | This module is for anyone who has ever created or wanted to create a |
771 | module for the Class:: namespace. The tools which this module provides |
772 | make doing complex Perl 5 wizardry simpler, by removing such barriers |
773 | as the need to hack symbol tables, or understand the fine details of |
774 | method dispatch. |
775 | |
776 | =head2 What changes do I have to make to use this module? |
777 | |
778 | This module was designed to be as unintrusive as possible. Many of its |
779 | features are accessible without B<any> change to your existing |
780 | code. It is meant to be a compliment to your existing code and not an |
781 | intrusion on your code base. Unlike many other B<Class::> modules, |
782 | this module B<does not> require you subclass it, or even that you |
783 | C<use> it in within your module's package. |
784 | |
785 | The only features which requires additions to your code are the |
786 | attribute handling and instance construction features, and these are |
787 | both completely optional features. The only reason for this is because |
788 | Perl 5's object system does not actually have these features built |
789 | in. More information about this feature can be found below. |
790 | |
791 | =head2 About Performance |
792 | |
793 | It is a common misconception that explicit MOPs are a performance hit. |
794 | This is not a universal truth, it is a side-effect of some specific |
795 | implementations. For instance, using Java reflection is slow because |
796 | the JVM cannot take advantage of any compiler optimizations, and the |
797 | JVM has to deal with much more runtime type information as well. |
798 | |
799 | Reflection in C# is marginally better as it was designed into the |
800 | language and runtime (the CLR). In contrast, CLOS (the Common Lisp |
801 | Object System) was built to support an explicit MOP, and so |
802 | performance is tuned for it. |
803 | |
804 | This library in particular does its absolute best to avoid putting |
805 | B<any> drain at all upon your code's performance. In fact, by itself |
806 | it does nothing to affect your existing code. So you only pay for what |
807 | you actually use. |
808 | |
809 | =head2 About Metaclass compatibility |
810 | |
811 | This module makes sure that all metaclasses created are both upwards |
812 | and downwards compatible. The topic of metaclass compatibility is |
813 | highly esoteric and is something only encountered when doing deep and |
814 | involved metaclass hacking. There are two basic kinds of metaclass |
815 | incompatibility; upwards and downwards. |
816 | |
817 | Upwards metaclass compatibility means that the metaclass of a |
818 | given class is either the same as (or a subclass of) all of the |
819 | class's ancestors. |
820 | |
821 | Downward metaclass compatibility means that the metaclasses of a |
822 | given class's ancestors are all either the same as (or a subclass |
823 | of) that metaclass. |
824 | |
825 | Here is a diagram showing a set of two classes (C<A> and C<B>) and |
826 | two metaclasses (C<Meta::A> and C<Meta::B>) which have correct |
827 | metaclass compatibility both upwards and downwards. |
828 | |
829 | +---------+ +---------+ |
830 | | Meta::A |<----| Meta::B | <....... (instance of ) |
831 | +---------+ +---------+ <------- (inherits from) |
832 | ^ ^ |
833 | : : |
834 | +---------+ +---------+ |
835 | | A |<----| B | |
836 | +---------+ +---------+ |
837 | |
838 | In actuality, I<all> of a class's metaclasses must be compatible, |
839 | not just the class metaclass. That includes the instance, attribute, |
840 | and method metaclasses, as well as the constructor and destructor |
841 | classes. |
842 | |
843 | C<Class::MOP> will attempt to fix some simple types of |
844 | incompatibilities. If all the metaclasses for the parent class are |
845 | I<subclasses> of the child's metaclasses then we can simply replace |
846 | the child's metaclasses with the parent's. In addition, if the child |
847 | is missing a metaclass that the parent has, we can also just make the |
848 | child use the parent's metaclass. |
849 | |
850 | As I said this is a highly esoteric topic and one you will only run |
851 | into if you do a lot of subclassing of L<Class::MOP::Class>. If you |
852 | are interested in why this is an issue see the paper I<Uniform and |
853 | safe metaclass composition> linked to in the L<SEE ALSO> section of |
854 | this document. |
855 | |
856 | =head2 Using custom metaclasses |
857 | |
858 | Always use the L<metaclass> pragma when using a custom metaclass, this |
859 | will ensure the proper initialization order and not accidentally |
860 | create an incorrect type of metaclass for you. This is a very rare |
861 | problem, and one which can only occur if you are doing deep metaclass |
862 | programming. So in other words, don't worry about it. |
863 | |
864 | Note that if you're using L<Moose> we encourage you to I<not> use |
865 | L<metaclass> pragma, and instead use L<Moose::Util::MetaRole> to apply |
866 | roles to a class's metaclasses. This topic is covered at length in |
867 | various L<Moose::Cookbook> recipes. |
868 | |
869 | =head1 PROTOCOLS |
870 | |
871 | The meta-object protocol is divided into 4 main sub-protocols: |
872 | |
873 | =head2 The Class protocol |
874 | |
875 | This provides a means of manipulating and introspecting a Perl 5 |
876 | class. It handles symbol table hacking for you, and provides a rich |
877 | set of methods that go beyond simple package introspection. |
878 | |
879 | See L<Class::MOP::Class> for more details. |
880 | |
881 | =head2 The Attribute protocol |
882 | |
883 | This provides a consistent representation for an attribute of a Perl 5 |
884 | class. Since there are so many ways to create and handle attributes in |
885 | Perl 5 OO, the Attribute protocol provide as much of a unified |
886 | approach as possible. Of course, you are always free to extend this |
887 | protocol by subclassing the appropriate classes. |
888 | |
889 | See L<Class::MOP::Attribute> for more details. |
890 | |
891 | =head2 The Method protocol |
892 | |
893 | This provides a means of manipulating and introspecting methods in the |
894 | Perl 5 object system. As with attributes, there are many ways to |
895 | approach this topic, so we try to keep it pretty basic, while still |
896 | making it possible to extend the system in many ways. |
897 | |
898 | See L<Class::MOP::Method> for more details. |
899 | |
900 | =head2 The Instance protocol |
901 | |
902 | This provides a layer of abstraction for creating object instances. |
903 | Since the other layers use this protocol, it is relatively easy to |
904 | change the type of your instances from the default hash reference to |
905 | some other type of reference. Several examples are provided in the |
906 | F<examples/> directory included in this distribution. |
907 | |
908 | See L<Class::MOP::Instance> for more details. |
909 | |
910 | =head1 FUNCTIONS |
911 | |
912 | Note that this module does not export any constants or functions. |
913 | |
38bf2a25 |
914 | =head2 Utility functions |
915 | |
916 | Note that these are all called as B<functions, not methods>. |
917 | |
918 | =over 4 |
919 | |
38bf2a25 |
920 | =item B<Class::MOP::get_code_info($code)> |
921 | |
922 | This function returns two values, the name of the package the C<$code> |
923 | is from and the name of the C<$code> itself. This is used by several |
924 | elements of the MOP to determine where a given C<$code> reference is |
925 | from. |
926 | |
927 | =item B<Class::MOP::class_of($instance_or_class_name)> |
928 | |
929 | This will return the metaclass of the given instance or class name. If the |
930 | class lacks a metaclass, no metaclass will be initialized, and C<undef> will be |
931 | returned. |
932 | |
38bf2a25 |
933 | =back |
934 | |
935 | =head2 Metaclass cache functions |
936 | |
937 | Class::MOP holds a cache of metaclasses. The following are functions |
938 | (B<not methods>) which can be used to access that cache. It is not |
939 | recommended that you mess with these. Bad things could happen, but if |
940 | you are brave and willing to risk it: go for it! |
941 | |
942 | =over 4 |
943 | |
944 | =item B<Class::MOP::get_all_metaclasses> |
945 | |
946 | This will return a hash of all the metaclass instances that have |
947 | been cached by L<Class::MOP::Class>, keyed by the package name. |
948 | |
949 | =item B<Class::MOP::get_all_metaclass_instances> |
950 | |
951 | This will return a list of all the metaclass instances that have |
952 | been cached by L<Class::MOP::Class>. |
953 | |
954 | =item B<Class::MOP::get_all_metaclass_names> |
955 | |
956 | This will return a list of all the metaclass names that have |
957 | been cached by L<Class::MOP::Class>. |
958 | |
959 | =item B<Class::MOP::get_metaclass_by_name($name)> |
960 | |
961 | This will return a cached L<Class::MOP::Class> instance, or nothing |
962 | if no metaclass exists with that C<$name>. |
963 | |
964 | =item B<Class::MOP::store_metaclass_by_name($name, $meta)> |
965 | |
966 | This will store a metaclass in the cache at the supplied C<$key>. |
967 | |
968 | =item B<Class::MOP::weaken_metaclass($name)> |
969 | |
970 | In rare cases (e.g. anonymous metaclasses) it is desirable to |
971 | store a weakened reference in the metaclass cache. This |
972 | function will weaken the reference to the metaclass stored |
973 | in C<$name>. |
974 | |
975 | =item B<Class::MOP::metaclass_is_weak($name)> |
976 | |
977 | Returns true if the metaclass for C<$name> has been weakened |
978 | (via C<weaken_metaclass>). |
979 | |
980 | =item B<Class::MOP::does_metaclass_exist($name)> |
981 | |
982 | This will return true of there exists a metaclass stored in the |
983 | C<$name> key, and return false otherwise. |
984 | |
985 | =item B<Class::MOP::remove_metaclass_by_name($name)> |
986 | |
987 | This will remove the metaclass stored in the C<$name> key. |
988 | |
989 | =back |
990 | |
fdbd9eaa |
991 | Some utility functions (such as C<Class::MOP::load_class>) that were |
992 | previously defined in C<Class::MOP> regarding loading of classes have been |
139cac7b |
993 | extracted to L<Class::Load>. Please see L<Class::Load> for documentation. |
72b39f99 |
994 | |
38bf2a25 |
995 | =head1 SEE ALSO |
996 | |
997 | =head2 Books |
998 | |
999 | There are very few books out on Meta Object Protocols and Metaclasses |
1000 | because it is such an esoteric topic. The following books are really |
1001 | the only ones I have found. If you know of any more, B<I<please>> |
1002 | email me and let me know, I would love to hear about them. |
1003 | |
1004 | =over 4 |
1005 | |
1006 | =item I<The Art of the Meta Object Protocol> |
1007 | |
1008 | =item I<Advances in Object-Oriented Metalevel Architecture and Reflection> |
1009 | |
1010 | =item I<Putting MetaClasses to Work> |
1011 | |
1012 | =item I<Smalltalk: The Language> |
1013 | |
1014 | =back |
1015 | |
1016 | =head2 Papers |
1017 | |
1018 | =over 4 |
1019 | |
1020 | =item "Uniform and safe metaclass composition" |
1021 | |
1022 | An excellent paper by the people who brought us the original Traits paper. |
1023 | This paper is on how Traits can be used to do safe metaclass composition, |
1024 | and offers an excellent introduction section which delves into the topic of |
1025 | metaclass compatibility. |
1026 | |
1027 | L<http://www.iam.unibe.ch/~scg/Archive/Papers/Duca05ySafeMetaclassTrait.pdf> |
1028 | |
1029 | =item "Safe Metaclass Programming" |
1030 | |
1031 | This paper seems to precede the above paper, and propose a mix-in based |
1032 | approach as opposed to the Traits based approach. Both papers have similar |
1033 | information on the metaclass compatibility problem space. |
1034 | |
1035 | L<http://citeseer.ist.psu.edu/37617.html> |
1036 | |
1037 | =back |
1038 | |
1039 | =head2 Prior Art |
1040 | |
1041 | =over 4 |
1042 | |
1043 | =item The Perl 6 MetaModel work in the Pugs project |
1044 | |
1045 | =over 4 |
1046 | |
1047 | =item L<http://svn.openfoundry.org/pugs/misc/Perl-MetaModel/> |
1048 | |
1049 | =item L<http://github.com/perl6/p5-modules/tree/master/Perl6-ObjectSpace/> |
1050 | |
1051 | =back |
1052 | |
1053 | =back |
1054 | |
1055 | =head2 Articles |
1056 | |
1057 | =over 4 |
1058 | |
1059 | =item CPAN Module Review of Class::MOP |
1060 | |
1061 | L<http://www.oreillynet.com/onlamp/blog/2006/06/cpan_module_review_classmop.html> |
1062 | |
1063 | =back |
1064 | |
1065 | =head1 SIMILAR MODULES |
1066 | |
1067 | As I have said above, this module is a class-builder-builder, so it is |
1068 | not the same thing as modules like L<Class::Accessor> and |
1069 | L<Class::MethodMaker>. That being said there are very few modules on CPAN |
1070 | with similar goals to this module. The one I have found which is most |
69229b40 |
1071 | like this module is L<Class::Meta>, although its philosophy and the MOP it |
38bf2a25 |
1072 | creates are very different from this modules. |
1073 | |
1074 | =head1 BUGS |
1075 | |
1076 | All complex software has bugs lurking in it, and this module is no |
1077 | exception. |
1078 | |
1079 | Please report any bugs to C<bug-class-mop@rt.cpan.org>, or through the |
1080 | web interface at L<http://rt.cpan.org>. |
1081 | |
1082 | You can also discuss feature requests or possible bugs on the Moose |
1083 | mailing list (moose@perl.org) or on IRC at |
1084 | L<irc://irc.perl.org/#moose>. |
1085 | |
1086 | =head1 ACKNOWLEDGEMENTS |
1087 | |
1088 | =over 4 |
1089 | |
1090 | =item Rob Kinyon |
1091 | |
1092 | Thanks to Rob for actually getting the development of this module kick-started. |
1093 | |
1094 | =back |
1095 | |
1096 | =cut |