Commit | Line | Data |
94b19069 |
1 | |
2 | package Class::MOP; |
3 | |
4 | use strict; |
5 | use warnings; |
6 | |
727919c5 |
7 | use Carp 'confess'; |
be7677c7 |
8 | use Scalar::Util 'weaken'; |
8b978dd5 |
9 | |
2eb717d5 |
10 | use Class::MOP::Class; |
11 | use Class::MOP::Attribute; |
12 | use Class::MOP::Method; |
13 | |
c23184fc |
14 | use Class::MOP::Immutable; |
857f87a7 |
15 | |
4c4a6c41 |
16 | our $VERSION = '0.49'; |
f0480c45 |
17 | our $AUTHORITY = 'cpan:STEVAN'; |
94b19069 |
18 | |
e0e4674a |
19 | use XSLoader; |
20 | XSLoader::load( 'Class::MOP', $VERSION ); |
21 | |
be7677c7 |
22 | { |
23 | # Metaclasses are singletons, so we cache them here. |
24 | # there is no need to worry about destruction though |
25 | # because they should die only when the program dies. |
26 | # After all, do package definitions even get reaped? |
1d68af04 |
27 | my %METAS; |
28 | |
29 | # means of accessing all the metaclasses that have |
be7677c7 |
30 | # been initialized thus far (for mugwumps obj browser) |
1d68af04 |
31 | sub get_all_metaclasses { %METAS } |
32 | sub get_all_metaclass_instances { values %METAS } |
33 | sub get_all_metaclass_names { keys %METAS } |
be7677c7 |
34 | sub get_metaclass_by_name { $METAS{$_[0]} } |
1d68af04 |
35 | sub store_metaclass_by_name { $METAS{$_[0]} = $_[1] } |
36 | sub weaken_metaclass { weaken($METAS{$_[0]}) } |
be7677c7 |
37 | sub does_metaclass_exist { exists $METAS{$_[0]} && defined $METAS{$_[0]} } |
1d68af04 |
38 | sub remove_metaclass_by_name { $METAS{$_[0]} = undef } |
39 | |
be7677c7 |
40 | # NOTE: |
1d68af04 |
41 | # We only cache metaclasses, meaning instances of |
42 | # Class::MOP::Class. We do not cache instance of |
be7677c7 |
43 | # Class::MOP::Package or Class::MOP::Module. Mostly |
1d68af04 |
44 | # because I don't yet see a good reason to do so. |
be7677c7 |
45 | } |
46 | |
448b6e55 |
47 | sub load_class { |
48 | my $class = shift; |
1d68af04 |
49 | # see if this is already |
448b6e55 |
50 | # loaded in the symbol table |
51 | return 1 if is_class_loaded($class); |
52 | # otherwise require it ... |
53 | my $file = $class . '.pm'; |
54 | $file =~ s{::}{/}g; |
55 | eval { CORE::require($file) }; |
56 | confess "Could not load class ($class) because : $@" if $@; |
57 | unless (does_metaclass_exist($class)) { |
58 | eval { Class::MOP::Class->initialize($class) }; |
1d68af04 |
59 | confess "Could not initialize class ($class) because : $@" if $@; |
448b6e55 |
60 | } |
61 | 1; # return true if it worked |
62 | } |
63 | |
64 | sub is_class_loaded { |
1d68af04 |
65 | my $class = shift; |
66 | no strict 'refs'; |
67 | return 1 if defined ${"${class}::VERSION"} || defined @{"${class}::ISA"}; |
68 | foreach (keys %{"${class}::"}) { |
69 | next if substr($_, -2, 2) eq '::'; |
70 | return 1 if defined &{"${class}::$_"}; |
71 | } |
72 | return 0; |
448b6e55 |
73 | } |
74 | |
75 | |
aa448b16 |
76 | ## ---------------------------------------------------------------------------- |
77 | ## Setting up our environment ... |
78 | ## ---------------------------------------------------------------------------- |
1d68af04 |
79 | ## Class::MOP needs to have a few things in the global perl environment so |
aa448b16 |
80 | ## that it can operate effectively. Those things are done here. |
81 | ## ---------------------------------------------------------------------------- |
82 | |
3bf7644b |
83 | # ... nothing yet actually ;) |
8b978dd5 |
84 | |
b51af7f9 |
85 | ## ---------------------------------------------------------------------------- |
1d68af04 |
86 | ## Bootstrapping |
b51af7f9 |
87 | ## ---------------------------------------------------------------------------- |
1d68af04 |
88 | ## The code below here is to bootstrap our MOP with itself. This is also |
b51af7f9 |
89 | ## sometimes called "tying the knot". By doing this, we make it much easier |
90 | ## to extend the MOP through subclassing and such since now you can use the |
1d68af04 |
91 | ## MOP itself to extend itself. |
92 | ## |
b51af7f9 |
93 | ## Yes, I know, thats weird and insane, but it's a good thing, trust me :) |
1d68af04 |
94 | ## ---------------------------------------------------------------------------- |
727919c5 |
95 | |
1d68af04 |
96 | # We need to add in the meta-attributes here so that |
97 | # any subclass of Class::MOP::* will be able to |
727919c5 |
98 | # inherit them using &construct_instance |
99 | |
f0480c45 |
100 | ## -------------------------------------------------------- |
6d5355c3 |
101 | ## Class::MOP::Package |
727919c5 |
102 | |
6d5355c3 |
103 | Class::MOP::Package->meta->add_attribute( |
c23184fc |
104 | Class::MOP::Attribute->new('$!package' => ( |
b880e0de |
105 | reader => { |
1d68af04 |
106 | # NOTE: we need to do this in order |
107 | # for the instance meta-object to |
b880e0de |
108 | # not fall into meta-circular death |
1d68af04 |
109 | # |
ce2ae40f |
110 | # we just alias the original method |
1d68af04 |
111 | # rather than re-produce it here |
ce2ae40f |
112 | 'name' => \&Class::MOP::Package::name |
b880e0de |
113 | }, |
c23184fc |
114 | init_arg => 'package', |
727919c5 |
115 | )) |
116 | ); |
117 | |
a5e51f0b |
118 | Class::MOP::Package->meta->add_attribute( |
c23184fc |
119 | Class::MOP::Attribute->new('%!namespace' => ( |
a5e51f0b |
120 | reader => { |
56dcfc1a |
121 | # NOTE: |
ce2ae40f |
122 | # we just alias the original method |
123 | # rather than re-produce it here |
124 | 'namespace' => \&Class::MOP::Package::namespace |
a5e51f0b |
125 | }, |
126 | # NOTE: |
1d68af04 |
127 | # protect this from silliness |
a2ee6c61 |
128 | init_arg => '!............( DO NOT DO THIS )............!', |
c4260b45 |
129 | default => sub { \undef } |
a5e51f0b |
130 | )) |
131 | ); |
132 | |
9d6dce77 |
133 | # NOTE: |
134 | # use the metaclass to construct the meta-package |
135 | # which is a superclass of the metaclass itself :P |
136 | Class::MOP::Package->meta->add_method('initialize' => sub { |
137 | my $class = shift; |
138 | my $package_name = shift; |
1d68af04 |
139 | $class->meta->new_object('package' => $package_name, @_); |
9d6dce77 |
140 | }); |
141 | |
f0480c45 |
142 | ## -------------------------------------------------------- |
143 | ## Class::MOP::Module |
144 | |
145 | # NOTE: |
1d68af04 |
146 | # yeah this is kind of stretching things a bit, |
f0480c45 |
147 | # but truthfully the version should be an attribute |
1d68af04 |
148 | # of the Module, the weirdness comes from having to |
149 | # stick to Perl 5 convention and store it in the |
150 | # $VERSION package variable. Basically if you just |
151 | # squint at it, it will look how you want it to look. |
f0480c45 |
152 | # Either as a package variable, or as a attribute of |
153 | # the metaclass, isn't abstraction great :) |
154 | |
155 | Class::MOP::Module->meta->add_attribute( |
c23184fc |
156 | Class::MOP::Attribute->new('$!version' => ( |
f0480c45 |
157 | reader => { |
ce2ae40f |
158 | # NOTE: |
159 | # we just alias the original method |
1d68af04 |
160 | # rather than re-produce it here |
ce2ae40f |
161 | 'version' => \&Class::MOP::Module::version |
f0480c45 |
162 | }, |
163 | # NOTE: |
1d68af04 |
164 | # protect this from silliness |
f0480c45 |
165 | init_arg => '!............( DO NOT DO THIS )............!', |
c4260b45 |
166 | default => sub { \undef } |
f0480c45 |
167 | )) |
168 | ); |
169 | |
170 | # NOTE: |
1d68af04 |
171 | # By following the same conventions as version here, |
172 | # we are opening up the possibility that people can |
173 | # use the $AUTHORITY in non-Class::MOP modules as |
174 | # well. |
f0480c45 |
175 | |
176 | Class::MOP::Module->meta->add_attribute( |
c23184fc |
177 | Class::MOP::Attribute->new('$!authority' => ( |
f0480c45 |
178 | reader => { |
ce2ae40f |
179 | # NOTE: |
180 | # we just alias the original method |
1d68af04 |
181 | # rather than re-produce it here |
ce2ae40f |
182 | 'authority' => \&Class::MOP::Module::authority |
1d68af04 |
183 | }, |
f0480c45 |
184 | # NOTE: |
1d68af04 |
185 | # protect this from silliness |
f0480c45 |
186 | init_arg => '!............( DO NOT DO THIS )............!', |
c4260b45 |
187 | default => sub { \undef } |
f0480c45 |
188 | )) |
189 | ); |
190 | |
191 | ## -------------------------------------------------------- |
6d5355c3 |
192 | ## Class::MOP::Class |
193 | |
727919c5 |
194 | Class::MOP::Class->meta->add_attribute( |
c23184fc |
195 | Class::MOP::Attribute->new('%!attributes' => ( |
f7259199 |
196 | reader => { |
1d68af04 |
197 | # NOTE: we need to do this in order |
198 | # for the instance meta-object to |
199 | # not fall into meta-circular death |
200 | # |
ce2ae40f |
201 | # we just alias the original method |
1d68af04 |
202 | # rather than re-produce it here |
ce2ae40f |
203 | 'get_attribute_map' => \&Class::MOP::Class::get_attribute_map |
f7259199 |
204 | }, |
c23184fc |
205 | init_arg => 'attributes', |
727919c5 |
206 | default => sub { {} } |
207 | )) |
208 | ); |
209 | |
351bd7d4 |
210 | Class::MOP::Class->meta->add_attribute( |
c23184fc |
211 | Class::MOP::Attribute->new('%!methods' => ( |
212 | init_arg => 'methods', |
1d68af04 |
213 | reader => { |
ce2ae40f |
214 | # NOTE: |
215 | # we just alias the original method |
1d68af04 |
216 | # rather than re-produce it here |
ce2ae40f |
217 | 'get_method_map' => \&Class::MOP::Class::get_method_map |
92330ee2 |
218 | }, |
7855ddba |
219 | default => sub { {} } |
c4260b45 |
220 | )) |
221 | ); |
222 | |
223 | Class::MOP::Class->meta->add_attribute( |
c23184fc |
224 | Class::MOP::Attribute->new('@!superclasses' => ( |
225 | accessor => { |
226 | # NOTE: |
227 | # we just alias the original method |
1d68af04 |
228 | # rather than re-produce it here |
c23184fc |
229 | 'superclasses' => \&Class::MOP::Class::superclasses |
230 | }, |
231 | # NOTE: |
1d68af04 |
232 | # protect this from silliness |
c23184fc |
233 | init_arg => '!............( DO NOT DO THIS )............!', |
234 | default => sub { \undef } |
235 | )) |
236 | ); |
237 | |
238 | Class::MOP::Class->meta->add_attribute( |
239 | Class::MOP::Attribute->new('$!attribute_metaclass' => ( |
1d68af04 |
240 | reader => { |
6d2118a4 |
241 | # NOTE: |
242 | # we just alias the original method |
1d68af04 |
243 | # rather than re-produce it here |
6d2118a4 |
244 | 'attribute_metaclass' => \&Class::MOP::Class::attribute_metaclass |
1d68af04 |
245 | }, |
c23184fc |
246 | init_arg => 'attribute_metaclass', |
351bd7d4 |
247 | default => 'Class::MOP::Attribute', |
248 | )) |
249 | ); |
250 | |
251 | Class::MOP::Class->meta->add_attribute( |
c23184fc |
252 | Class::MOP::Attribute->new('$!method_metaclass' => ( |
1d68af04 |
253 | reader => { |
6d2118a4 |
254 | # NOTE: |
255 | # we just alias the original method |
1d68af04 |
256 | # rather than re-produce it here |
6d2118a4 |
257 | 'method_metaclass' => \&Class::MOP::Class::method_metaclass |
258 | }, |
c23184fc |
259 | init_arg => 'method_metaclass', |
1d68af04 |
260 | default => 'Class::MOP::Method', |
351bd7d4 |
261 | )) |
262 | ); |
263 | |
2bab2be6 |
264 | Class::MOP::Class->meta->add_attribute( |
c23184fc |
265 | Class::MOP::Attribute->new('$!instance_metaclass' => ( |
b880e0de |
266 | reader => { |
1d68af04 |
267 | # NOTE: we need to do this in order |
268 | # for the instance meta-object to |
269 | # not fall into meta-circular death |
270 | # |
ce2ae40f |
271 | # we just alias the original method |
1d68af04 |
272 | # rather than re-produce it here |
ce2ae40f |
273 | 'instance_metaclass' => \&Class::MOP::Class::instance_metaclass |
b880e0de |
274 | }, |
c23184fc |
275 | init_arg => 'instance_metaclass', |
1d68af04 |
276 | default => 'Class::MOP::Instance', |
2bab2be6 |
277 | )) |
278 | ); |
279 | |
9d6dce77 |
280 | # NOTE: |
1d68af04 |
281 | # we don't actually need to tie the knot with |
282 | # Class::MOP::Class here, it is actually handled |
283 | # within Class::MOP::Class itself in the |
284 | # construct_class_instance method. |
9d6dce77 |
285 | |
f0480c45 |
286 | ## -------------------------------------------------------- |
727919c5 |
287 | ## Class::MOP::Attribute |
288 | |
7b31baf4 |
289 | Class::MOP::Attribute->meta->add_attribute( |
c23184fc |
290 | Class::MOP::Attribute->new('$!name' => ( |
291 | init_arg => 'name', |
292 | reader => { |
1d68af04 |
293 | # NOTE: we need to do this in order |
294 | # for the instance meta-object to |
295 | # not fall into meta-circular death |
296 | # |
ce2ae40f |
297 | # we just alias the original method |
1d68af04 |
298 | # rather than re-produce it here |
ce2ae40f |
299 | 'name' => \&Class::MOP::Attribute::name |
b880e0de |
300 | } |
7b31baf4 |
301 | )) |
302 | ); |
303 | |
304 | Class::MOP::Attribute->meta->add_attribute( |
c23184fc |
305 | Class::MOP::Attribute->new('$!associated_class' => ( |
306 | init_arg => 'associated_class', |
307 | reader => { |
1d68af04 |
308 | # NOTE: we need to do this in order |
309 | # for the instance meta-object to |
310 | # not fall into meta-circular death |
311 | # |
ce2ae40f |
312 | # we just alias the original method |
1d68af04 |
313 | # rather than re-produce it here |
ce2ae40f |
314 | 'associated_class' => \&Class::MOP::Attribute::associated_class |
b880e0de |
315 | } |
7b31baf4 |
316 | )) |
317 | ); |
318 | |
319 | Class::MOP::Attribute->meta->add_attribute( |
c23184fc |
320 | Class::MOP::Attribute->new('$!accessor' => ( |
321 | init_arg => 'accessor', |
6d2118a4 |
322 | reader => { 'accessor' => \&Class::MOP::Attribute::accessor }, |
323 | predicate => { 'has_accessor' => \&Class::MOP::Attribute::has_accessor }, |
7b31baf4 |
324 | )) |
325 | ); |
326 | |
327 | Class::MOP::Attribute->meta->add_attribute( |
c23184fc |
328 | Class::MOP::Attribute->new('$!reader' => ( |
329 | init_arg => 'reader', |
6d2118a4 |
330 | reader => { 'reader' => \&Class::MOP::Attribute::reader }, |
331 | predicate => { 'has_reader' => \&Class::MOP::Attribute::has_reader }, |
7b31baf4 |
332 | )) |
333 | ); |
334 | |
335 | Class::MOP::Attribute->meta->add_attribute( |
c23184fc |
336 | Class::MOP::Attribute->new('$!writer' => ( |
337 | init_arg => 'writer', |
6d2118a4 |
338 | reader => { 'writer' => \&Class::MOP::Attribute::writer }, |
339 | predicate => { 'has_writer' => \&Class::MOP::Attribute::has_writer }, |
7b31baf4 |
340 | )) |
341 | ); |
342 | |
343 | Class::MOP::Attribute->meta->add_attribute( |
c23184fc |
344 | Class::MOP::Attribute->new('$!predicate' => ( |
345 | init_arg => 'predicate', |
6d2118a4 |
346 | reader => { 'predicate' => \&Class::MOP::Attribute::predicate }, |
347 | predicate => { 'has_predicate' => \&Class::MOP::Attribute::has_predicate }, |
7b31baf4 |
348 | )) |
349 | ); |
350 | |
351 | Class::MOP::Attribute->meta->add_attribute( |
c23184fc |
352 | Class::MOP::Attribute->new('$!clearer' => ( |
353 | init_arg => 'clearer', |
6d2118a4 |
354 | reader => { 'clearer' => \&Class::MOP::Attribute::clearer }, |
355 | predicate => { 'has_clearer' => \&Class::MOP::Attribute::has_clearer }, |
7d28758b |
356 | )) |
357 | ); |
358 | |
359 | Class::MOP::Attribute->meta->add_attribute( |
1d68af04 |
360 | Class::MOP::Attribute->new('$!builder' => ( |
361 | init_arg => 'builder', |
362 | reader => { 'builder' => \&Class::MOP::Attribute::builder }, |
363 | predicate => { 'has_builder' => \&Class::MOP::Attribute::has_builder }, |
364 | )) |
365 | ); |
366 | |
367 | Class::MOP::Attribute->meta->add_attribute( |
c23184fc |
368 | Class::MOP::Attribute->new('$!init_arg' => ( |
369 | init_arg => 'init_arg', |
6d2118a4 |
370 | reader => { 'init_arg' => \&Class::MOP::Attribute::init_arg }, |
371 | predicate => { 'has_init_arg' => \&Class::MOP::Attribute::has_init_arg }, |
7b31baf4 |
372 | )) |
373 | ); |
374 | |
375 | Class::MOP::Attribute->meta->add_attribute( |
c23184fc |
376 | Class::MOP::Attribute->new('$!default' => ( |
377 | init_arg => 'default', |
7b31baf4 |
378 | # default has a custom 'reader' method ... |
1d68af04 |
379 | predicate => { 'has_default' => \&Class::MOP::Attribute::has_default }, |
7b31baf4 |
380 | )) |
381 | ); |
382 | |
3545c727 |
383 | Class::MOP::Attribute->meta->add_attribute( |
c23184fc |
384 | Class::MOP::Attribute->new('@!associated_methods' => ( |
385 | init_arg => 'associated_methods', |
386 | reader => { 'associated_methods' => \&Class::MOP::Attribute::associated_methods }, |
1d68af04 |
387 | default => sub { [] } |
3545c727 |
388 | )) |
389 | ); |
727919c5 |
390 | |
391 | # NOTE: (meta-circularity) |
392 | # This should be one of the last things done |
393 | # it will "tie the knot" with Class::MOP::Attribute |
1d68af04 |
394 | # so that it uses the attributes meta-objects |
395 | # to construct itself. |
727919c5 |
396 | Class::MOP::Attribute->meta->add_method('new' => sub { |
397 | my $class = shift; |
398 | my $name = shift; |
1d68af04 |
399 | my %options = @_; |
400 | |
727919c5 |
401 | (defined $name && $name) |
402 | || confess "You must provide a name for the attribute"; |
1d68af04 |
403 | $options{init_arg} = $name |
5659d76e |
404 | if not exists $options{init_arg}; |
1d68af04 |
405 | |
406 | if(exists $options{builder}){ |
407 | confess("builder must be a defined scalar value which is a method name") |
408 | if ref $options{builder} || !(defined $options{builder}); |
409 | confess("Setting both default and builder is not allowed.") |
410 | if exists $options{default}; |
8fe581e5 |
411 | } else { |
412 | (Class::MOP::Attribute::is_default_a_coderef(\%options)) |
413 | || confess("References are not allowed as default values, you must ". |
414 | "wrap then in a CODE reference (ex: sub { [] } and not [])") |
415 | if exists $options{default} && ref $options{default}; |
1d68af04 |
416 | } |
5659d76e |
417 | # return the new object |
418 | $class->meta->new_object(name => $name, %options); |
419 | }); |
420 | |
421 | Class::MOP::Attribute->meta->add_method('clone' => sub { |
a740253a |
422 | my $self = shift; |
1d68af04 |
423 | $self->meta->clone_object($self, @_); |
727919c5 |
424 | }); |
425 | |
f0480c45 |
426 | ## -------------------------------------------------------- |
b6164407 |
427 | ## Class::MOP::Method |
428 | |
429 | Class::MOP::Method->meta->add_attribute( |
c23184fc |
430 | Class::MOP::Attribute->new('&!body' => ( |
431 | init_arg => 'body', |
432 | reader => { 'body' => \&Class::MOP::Method::body }, |
b6164407 |
433 | )) |
434 | ); |
435 | |
436 | ## -------------------------------------------------------- |
437 | ## Class::MOP::Method::Wrapped |
438 | |
439 | # NOTE: |
1d68af04 |
440 | # the way this item is initialized, this |
441 | # really does not follow the standard |
442 | # practices of attributes, but we put |
b6164407 |
443 | # it here for completeness |
444 | Class::MOP::Method::Wrapped->meta->add_attribute( |
c23184fc |
445 | Class::MOP::Attribute->new('%!modifier_table') |
b6164407 |
446 | ); |
447 | |
448 | ## -------------------------------------------------------- |
565f0cbb |
449 | ## Class::MOP::Method::Generated |
450 | |
451 | Class::MOP::Method::Generated->meta->add_attribute( |
452 | Class::MOP::Attribute->new('$!is_inline' => ( |
453 | init_arg => 'is_inline', |
454 | reader => { 'is_inline' => \&Class::MOP::Method::Generated::is_inline }, |
1d68af04 |
455 | )) |
565f0cbb |
456 | ); |
457 | |
458 | ## -------------------------------------------------------- |
d90b42a6 |
459 | ## Class::MOP::Method::Accessor |
460 | |
461 | Class::MOP::Method::Accessor->meta->add_attribute( |
c23184fc |
462 | Class::MOP::Attribute->new('$!attribute' => ( |
463 | init_arg => 'attribute', |
1d68af04 |
464 | reader => { |
465 | 'associated_attribute' => \&Class::MOP::Method::Accessor::associated_attribute |
d90b42a6 |
466 | }, |
1d68af04 |
467 | )) |
d90b42a6 |
468 | ); |
469 | |
470 | Class::MOP::Method::Accessor->meta->add_attribute( |
c23184fc |
471 | Class::MOP::Attribute->new('$!accessor_type' => ( |
472 | init_arg => 'accessor_type', |
473 | reader => { 'accessor_type' => \&Class::MOP::Method::Accessor::accessor_type }, |
1d68af04 |
474 | )) |
d90b42a6 |
475 | ); |
476 | |
d90b42a6 |
477 | |
478 | ## -------------------------------------------------------- |
479 | ## Class::MOP::Method::Constructor |
480 | |
481 | Class::MOP::Method::Constructor->meta->add_attribute( |
c23184fc |
482 | Class::MOP::Attribute->new('%!options' => ( |
483 | init_arg => 'options', |
1d68af04 |
484 | reader => { |
485 | 'options' => \&Class::MOP::Method::Constructor::options |
d90b42a6 |
486 | }, |
1d68af04 |
487 | )) |
d90b42a6 |
488 | ); |
489 | |
490 | Class::MOP::Method::Constructor->meta->add_attribute( |
c23184fc |
491 | Class::MOP::Attribute->new('$!associated_metaclass' => ( |
492 | init_arg => 'metaclass', |
1d68af04 |
493 | reader => { |
494 | 'associated_metaclass' => \&Class::MOP::Method::Constructor::associated_metaclass |
495 | }, |
496 | )) |
d90b42a6 |
497 | ); |
498 | |
499 | ## -------------------------------------------------------- |
86482605 |
500 | ## Class::MOP::Instance |
501 | |
502 | # NOTE: |
1d68af04 |
503 | # these don't yet do much of anything, but are just |
86482605 |
504 | # included for completeness |
505 | |
506 | Class::MOP::Instance->meta->add_attribute( |
c23184fc |
507 | Class::MOP::Attribute->new('$!meta') |
86482605 |
508 | ); |
509 | |
510 | Class::MOP::Instance->meta->add_attribute( |
c23184fc |
511 | Class::MOP::Attribute->new('@!slots') |
86482605 |
512 | ); |
513 | |
514 | ## -------------------------------------------------------- |
f0480c45 |
515 | ## Now close all the Class::MOP::* classes |
4d47b77f |
516 | |
0b9372a2 |
517 | # NOTE: |
1d68af04 |
518 | # we don't need to inline the |
519 | # constructors or the accessors |
520 | # this only lengthens the compile |
521 | # time of the MOP, and gives us |
0b9372a2 |
522 | # no actual benefits. |
523 | |
524 | $_->meta->make_immutable( |
525 | inline_constructor => 0, |
526 | inline_accessors => 0, |
527 | ) for qw/ |
1d68af04 |
528 | Class::MOP::Package |
529 | Class::MOP::Module |
530 | Class::MOP::Class |
531 | |
0b9372a2 |
532 | Class::MOP::Attribute |
1d68af04 |
533 | Class::MOP::Method |
534 | Class::MOP::Instance |
535 | |
536 | Class::MOP::Object |
0b9372a2 |
537 | |
565f0cbb |
538 | Class::MOP::Method::Generated |
1d68af04 |
539 | |
ba38bf08 |
540 | Class::MOP::Method::Accessor |
1d68af04 |
541 | Class::MOP::Method::Constructor |
542 | Class::MOP::Method::Wrapped |
0b9372a2 |
543 | /; |
b6164407 |
544 | |
94b19069 |
545 | 1; |
546 | |
547 | __END__ |
548 | |
549 | =pod |
550 | |
1d68af04 |
551 | =head1 NAME |
94b19069 |
552 | |
553 | Class::MOP - A Meta Object Protocol for Perl 5 |
554 | |
94b19069 |
555 | =head1 DESCRIPTON |
556 | |
1d68af04 |
557 | This module is an attempt to create a meta object protocol for the |
558 | Perl 5 object system. It makes no attempt to change the behavior or |
559 | characteristics of the Perl 5 object system, only to create a |
27e31eaf |
560 | protocol for its manipulation and introspection. |
94b19069 |
561 | |
1d68af04 |
562 | That said, it does attempt to create the tools for building a rich |
563 | set of extensions to the Perl 5 object system. Every attempt has been |
564 | made for these tools to keep to the spirit of the Perl 5 object |
94b19069 |
565 | system that we all know and love. |
566 | |
1d68af04 |
567 | This documentation is admittedly sparse on details, as time permits |
568 | I will try to improve them. For now, I suggest looking at the items |
569 | listed in the L<SEE ALSO> section for more information. In particular |
570 | the book "The Art of the Meta Object Protocol" was very influential |
40483095 |
571 | in the development of this system. |
572 | |
bfe4d0fc |
573 | =head2 What is a Meta Object Protocol? |
574 | |
1d68af04 |
575 | A meta object protocol is an API to an object system. |
bfe4d0fc |
576 | |
1d68af04 |
577 | To be more specific, it is a set of abstractions of the components of |
578 | an object system (typically things like; classes, object, methods, |
579 | object attributes, etc.). These abstractions can then be used to both |
bfe4d0fc |
580 | inspect and manipulate the object system which they describe. |
581 | |
1d68af04 |
582 | It can be said that there are two MOPs for any object system; the |
583 | implicit MOP, and the explicit MOP. The implicit MOP handles things |
584 | like method dispatch or inheritance, which happen automatically as |
585 | part of how the object system works. The explicit MOP typically |
586 | handles the introspection/reflection features of the object system. |
587 | All object systems have implicit MOPs, without one, they would not |
588 | work. Explict MOPs however as less common, and depending on the |
589 | language can vary from restrictive (Reflection in Java or C#) to |
590 | wide open (CLOS is a perfect example). |
bfe4d0fc |
591 | |
e16da3e6 |
592 | =head2 Yet Another Class Builder!! Why? |
593 | |
1d68af04 |
594 | This is B<not> a class builder so much as it is a I<class builder |
595 | B<builder>>. My intent is that an end user does not use this module |
596 | directly, but instead this module is used by module authors to |
597 | build extensions and features onto the Perl 5 object system. |
e16da3e6 |
598 | |
94b19069 |
599 | =head2 Who is this module for? |
600 | |
1d68af04 |
601 | This module is specifically for anyone who has ever created or |
602 | wanted to create a module for the Class:: namespace. The tools which |
603 | this module will provide will hopefully make it easier to do more |
604 | complex things with Perl 5 classes by removing such barriers as |
605 | the need to hack the symbol tables, or understand the fine details |
606 | of method dispatch. |
94b19069 |
607 | |
bfe4d0fc |
608 | =head2 What changes do I have to make to use this module? |
609 | |
1d68af04 |
610 | This module was designed to be as unintrusive as possible. Many of |
611 | its features are accessible without B<any> change to your existsing |
612 | code at all. It is meant to be a compliment to your existing code and |
613 | not an intrusion on your code base. Unlike many other B<Class::> |
614 | modules, this module B<does not> require you subclass it, or even that |
615 | you C<use> it in within your module's package. |
bfe4d0fc |
616 | |
1d68af04 |
617 | The only features which requires additions to your code are the |
2eb717d5 |
618 | attribute handling and instance construction features, and these are |
1d68af04 |
619 | both completely optional features. The only reason for this is because |
620 | Perl 5's object system does not actually have these features built |
2eb717d5 |
621 | in. More information about this feature can be found below. |
bfe4d0fc |
622 | |
623 | =head2 A Note about Performance? |
624 | |
1d68af04 |
625 | It is a common misconception that explict MOPs are performance drains. |
626 | But this is not a universal truth at all, it is an side-effect of |
627 | specific implementations. For instance, using Java reflection is much |
628 | slower because the JVM cannot take advantage of any compiler |
629 | optimizations, and the JVM has to deal with much more runtime type |
630 | information as well. Reflection in C# is marginally better as it was |
631 | designed into the language and runtime (the CLR). In contrast, CLOS |
632 | (the Common Lisp Object System) was built to support an explicit MOP, |
633 | and so performance is tuned for it. |
634 | |
635 | This library in particular does it's absolute best to avoid putting |
636 | B<any> drain at all upon your code's performance. In fact, by itself |
637 | it does nothing to affect your existing code. So you only pay for |
2eb717d5 |
638 | what you actually use. |
bfe4d0fc |
639 | |
550d56db |
640 | =head2 About Metaclass compatibility |
641 | |
1d68af04 |
642 | This module makes sure that all metaclasses created are both upwards |
643 | and downwards compatible. The topic of metaclass compatibility is |
644 | highly esoteric and is something only encountered when doing deep and |
645 | involved metaclass hacking. There are two basic kinds of metaclass |
646 | incompatibility; upwards and downwards. |
550d56db |
647 | |
1d68af04 |
648 | Upwards metaclass compatibility means that the metaclass of a |
649 | given class is either the same as (or a subclass of) all of the |
550d56db |
650 | class's ancestors. |
651 | |
1d68af04 |
652 | Downward metaclass compatibility means that the metaclasses of a |
653 | given class's anscestors are all either the same as (or a subclass |
550d56db |
654 | of) that metaclass. |
655 | |
1d68af04 |
656 | Here is a diagram showing a set of two classes (C<A> and C<B>) and |
657 | two metaclasses (C<Meta::A> and C<Meta::B>) which have correct |
550d56db |
658 | metaclass compatibility both upwards and downwards. |
659 | |
660 | +---------+ +---------+ |
661 | | Meta::A |<----| Meta::B | <....... (instance of ) |
1d68af04 |
662 | +---------+ +---------+ <------- (inherits from) |
550d56db |
663 | ^ ^ |
664 | : : |
665 | +---------+ +---------+ |
666 | | A |<----| B | |
667 | +---------+ +---------+ |
668 | |
1d68af04 |
669 | As I said this is a highly esoteric topic and one you will only run |
670 | into if you do a lot of subclassing of B<Class::MOP::Class>. If you |
671 | are interested in why this is an issue see the paper |
672 | I<Uniform and safe metaclass composition> linked to in the |
550d56db |
673 | L<SEE ALSO> section of this document. |
674 | |
aa448b16 |
675 | =head2 Using custom metaclasses |
676 | |
1d68af04 |
677 | Always use the metaclass pragma when using a custom metaclass, this |
678 | will ensure the proper initialization order and not accidentely |
679 | create an incorrect type of metaclass for you. This is a very rare |
680 | problem, and one which can only occur if you are doing deep metaclass |
aa448b16 |
681 | programming. So in other words, don't worry about it. |
682 | |
94b19069 |
683 | =head1 PROTOCOLS |
684 | |
685 | The protocol is divided into 3 main sub-protocols: |
686 | |
687 | =over 4 |
688 | |
689 | =item The Class protocol |
690 | |
1d68af04 |
691 | This provides a means of manipulating and introspecting a Perl 5 |
692 | class. It handles all of symbol table hacking for you, and provides |
94b19069 |
693 | a rich set of methods that go beyond simple package introspection. |
694 | |
552e3d24 |
695 | See L<Class::MOP::Class> for more details. |
696 | |
94b19069 |
697 | =item The Attribute protocol |
698 | |
1d68af04 |
699 | This provides a consistent represenation for an attribute of a |
700 | Perl 5 class. Since there are so many ways to create and handle |
701 | atttributes in Perl 5 OO, this attempts to provide as much of a |
702 | unified approach as possible, while giving the freedom and |
94b19069 |
703 | flexibility to subclass for specialization. |
704 | |
552e3d24 |
705 | See L<Class::MOP::Attribute> for more details. |
706 | |
94b19069 |
707 | =item The Method protocol |
708 | |
1d68af04 |
709 | This provides a means of manipulating and introspecting methods in |
710 | the Perl 5 object system. As with attributes, there are many ways to |
711 | approach this topic, so we try to keep it pretty basic, while still |
94b19069 |
712 | making it possible to extend the system in many ways. |
713 | |
552e3d24 |
714 | See L<Class::MOP::Method> for more details. |
94b19069 |
715 | |
716 | =back |
717 | |
be7677c7 |
718 | =head1 FUNCTIONS |
719 | |
448b6e55 |
720 | =head2 Utility functions |
721 | |
722 | =over 4 |
723 | |
724 | =item B<load_class ($class_name)> |
725 | |
1d68af04 |
726 | This will load a given C<$class_name> and if it does not have an |
448b6e55 |
727 | already initialized metaclass, then it will intialize one for it. |
728 | |
729 | =item B<is_class_loaded ($class_name)> |
730 | |
1d68af04 |
731 | This will return a boolean depending on if the C<$class_name> has |
732 | been loaded. |
448b6e55 |
733 | |
1d68af04 |
734 | NOTE: This does a basic check of the symbol table to try and |
448b6e55 |
735 | determine as best it can if the C<$class_name> is loaded, it |
1d68af04 |
736 | is probably correct about 99% of the time. |
448b6e55 |
737 | |
e0e4674a |
738 | =item B<check_package_cache_flag> |
739 | |
740 | =item B<get_code_info ($code)> |
741 | |
448b6e55 |
742 | =back |
743 | |
744 | =head2 Metaclass cache functions |
745 | |
1d68af04 |
746 | Class::MOP holds a cache of metaclasses, the following are functions |
747 | (B<not methods>) which can be used to access that cache. It is not |
748 | recommended that you mess with this, bad things could happen. But if |
be7677c7 |
749 | you are brave and willing to risk it, go for it. |
750 | |
751 | =over 4 |
752 | |
753 | =item B<get_all_metaclasses> |
754 | |
1d68af04 |
755 | This will return an hash of all the metaclass instances that have |
756 | been cached by B<Class::MOP::Class> keyed by the package name. |
b9d9fc0b |
757 | |
be7677c7 |
758 | =item B<get_all_metaclass_instances> |
759 | |
1d68af04 |
760 | This will return an array of all the metaclass instances that have |
b9d9fc0b |
761 | been cached by B<Class::MOP::Class>. |
762 | |
be7677c7 |
763 | =item B<get_all_metaclass_names> |
764 | |
1d68af04 |
765 | This will return an array of all the metaclass names that have |
b9d9fc0b |
766 | been cached by B<Class::MOP::Class>. |
767 | |
be7677c7 |
768 | =item B<get_metaclass_by_name ($name)> |
769 | |
770 | =item B<store_metaclass_by_name ($name, $meta)> |
771 | |
772 | =item B<weaken_metaclass ($name)> |
773 | |
774 | =item B<does_metaclass_exist ($name)> |
775 | |
776 | =item B<remove_metaclass_by_name ($name)> |
777 | |
778 | =back |
779 | |
552e3d24 |
780 | =head1 SEE ALSO |
8b978dd5 |
781 | |
552e3d24 |
782 | =head2 Books |
8b978dd5 |
783 | |
1d68af04 |
784 | There are very few books out on Meta Object Protocols and Metaclasses |
785 | because it is such an esoteric topic. The following books are really |
786 | the only ones I have found. If you know of any more, B<I<please>> |
a2e85e6c |
787 | email me and let me know, I would love to hear about them. |
788 | |
8b978dd5 |
789 | =over 4 |
790 | |
552e3d24 |
791 | =item "The Art of the Meta Object Protocol" |
8b978dd5 |
792 | |
552e3d24 |
793 | =item "Advances in Object-Oriented Metalevel Architecture and Reflection" |
8b978dd5 |
794 | |
b51af7f9 |
795 | =item "Putting MetaClasses to Work" |
796 | |
a2e85e6c |
797 | =item "Smalltalk: The Language" |
798 | |
94b19069 |
799 | =back |
800 | |
550d56db |
801 | =head2 Papers |
802 | |
803 | =over 4 |
804 | |
805 | =item Uniform and safe metaclass composition |
806 | |
1d68af04 |
807 | An excellent paper by the people who brought us the original Traits paper. |
808 | This paper is on how Traits can be used to do safe metaclass composition, |
809 | and offers an excellent introduction section which delves into the topic of |
550d56db |
810 | metaclass compatibility. |
811 | |
812 | L<http://www.iam.unibe.ch/~scg/Archive/Papers/Duca05ySafeMetaclassTrait.pdf> |
813 | |
814 | =item Safe Metaclass Programming |
815 | |
1d68af04 |
816 | This paper seems to precede the above paper, and propose a mix-in based |
817 | approach as opposed to the Traits based approach. Both papers have similar |
818 | information on the metaclass compatibility problem space. |
550d56db |
819 | |
820 | L<http://citeseer.ist.psu.edu/37617.html> |
821 | |
822 | =back |
823 | |
552e3d24 |
824 | =head2 Prior Art |
8b978dd5 |
825 | |
826 | =over 4 |
827 | |
7184ca14 |
828 | =item The Perl 6 MetaModel work in the Pugs project |
8b978dd5 |
829 | |
830 | =over 4 |
831 | |
552e3d24 |
832 | =item L<http://svn.openfoundry.org/pugs/perl5/Perl6-MetaModel> |
8b978dd5 |
833 | |
552e3d24 |
834 | =item L<http://svn.openfoundry.org/pugs/perl5/Perl6-ObjectSpace> |
8b978dd5 |
835 | |
836 | =back |
837 | |
94b19069 |
838 | =back |
839 | |
1d68af04 |
840 | =head2 Articles |
f8dfcfb7 |
841 | |
842 | =over 4 |
843 | |
1d68af04 |
844 | =item CPAN Module Review of Class::MOP |
f8dfcfb7 |
845 | |
846 | L<http://www.oreillynet.com/onlamp/blog/2006/06/cpan_module_review_classmop.html> |
847 | |
848 | =back |
849 | |
a2e85e6c |
850 | =head1 SIMILAR MODULES |
851 | |
1d68af04 |
852 | As I have said above, this module is a class-builder-builder, so it is |
853 | not the same thing as modules like L<Class::Accessor> and |
854 | L<Class::MethodMaker>. That being said there are very few modules on CPAN |
855 | with similar goals to this module. The one I have found which is most |
856 | like this module is L<Class::Meta>, although it's philosophy and the MOP it |
857 | creates are very different from this modules. |
94b19069 |
858 | |
a2e85e6c |
859 | =head1 BUGS |
860 | |
1d68af04 |
861 | All complex software has bugs lurking in it, and this module is no |
a2e85e6c |
862 | exception. If you find a bug please either email me, or add the bug |
863 | to cpan-RT. |
864 | |
865 | =head1 ACKNOWLEDGEMENTS |
866 | |
867 | =over 4 |
868 | |
b9d9fc0b |
869 | =item Rob Kinyon |
a2e85e6c |
870 | |
1d68af04 |
871 | Thanks to Rob for actually getting the development of this module kick-started. |
a2e85e6c |
872 | |
873 | =back |
874 | |
1a09d9cc |
875 | =head1 AUTHORS |
94b19069 |
876 | |
a2e85e6c |
877 | Stevan Little E<lt>stevan@iinteractive.comE<gt> |
552e3d24 |
878 | |
9c8cda90 |
879 | B<with contributions from:> |
880 | |
881 | Brandon (blblack) Black |
882 | |
883 | Guillermo (groditi) Roditi |
884 | |
9195ddff |
885 | Matt (mst) Trout |
886 | |
9c8cda90 |
887 | Rob (robkinyon) Kinyon |
888 | |
889 | Yuval (nothingmuch) Kogman |
1a09d9cc |
890 | |
94b19069 |
891 | =head1 COPYRIGHT AND LICENSE |
892 | |
2367814a |
893 | Copyright 2006, 2007 by Infinity Interactive, Inc. |
94b19069 |
894 | |
895 | L<http://www.iinteractive.com> |
896 | |
897 | This library is free software; you can redistribute it and/or modify |
1d68af04 |
898 | it under the same terms as Perl itself. |
94b19069 |
899 | |
900 | =cut |