Commit | Line | Data |
94b19069 |
1 | |
2 | package Class::MOP; |
3 | |
4 | use strict; |
5 | use warnings; |
6 | |
3cf322a0 |
7 | use MRO::Compat; |
8 | |
4c105333 |
9 | use Carp 'confess'; |
10 | use Scalar::Util 'weaken'; |
8b978dd5 |
11 | |
2eb717d5 |
12 | use Class::MOP::Class; |
13 | use Class::MOP::Attribute; |
14 | use Class::MOP::Method; |
15 | |
c23184fc |
16 | use Class::MOP::Immutable; |
857f87a7 |
17 | |
b1f5f41d |
18 | BEGIN { |
70ad0655 |
19 | |
2e5c1a3f |
20 | our $VERSION = '0.65'; |
b1f5f41d |
21 | our $AUTHORITY = 'cpan:STEVAN'; |
22 | |
11b56828 |
23 | *IS_RUNNING_ON_5_10 = ($] < 5.009_005) |
24 | ? sub () { 0 } |
4c105333 |
25 | : sub () { 1 }; |
46b23b44 |
26 | |
4c105333 |
27 | # NOTE: |
28 | # we may not use this yet, but once |
29 | # the get_code_info XS gets merged |
30 | # upstream to it, we will always use |
31 | # it. But for now it is just kinda |
32 | # extra overhead. |
33 | # - SL |
34 | require Sub::Identify; |
35 | |
36 | # stash these for a sec, and see how things go |
37 | my $_PP_subname = sub { $_[1] }; |
a982eca7 |
38 | my $_PP_get_code_info = \&Sub::Identify::get_code_info; |
4c105333 |
39 | |
e2d4fc55 |
40 | if ($ENV{CLASS_MOP_NO_XS}) { |
4c105333 |
41 | # NOTE: |
42 | # this is if you really want things |
43 | # to be slow, then you can force the |
44 | # no-XS rule this way, otherwise we |
45 | # make an effort to load as much of |
46 | # the XS as possible. |
47 | # - SL |
48 | no warnings 'prototype', 'redefine'; |
6c34db07 |
49 | |
3c489bcb |
50 | # this is either part of core or set up appropriately by MRO::Compat |
51 | *check_package_cache_flag = \&mro::get_pkg_gen; |
52 | |
4c105333 |
53 | # our own version of Sub::Name |
54 | *subname = $_PP_subname; |
55 | # and the Sub::Identify version of the get_code_info |
56 | *get_code_info = $_PP_get_code_info; |
57 | } |
58 | else { |
59 | # now try our best to get as much |
60 | # of the XS loaded as possible |
61 | { |
62 | local $@; |
63 | eval { |
64 | require XSLoader; |
65 | XSLoader::load( 'Class::MOP', $VERSION ); |
66 | }; |
67 | die $@ if $@ && $@ !~ /object version|loadable object/; |
68 | |
69 | # okay, so the XS failed to load, so |
70 | # use the pure perl one instead. |
71 | *get_code_info = $_PP_get_code_info if $@; |
72 | } |
73 | |
74 | # get it from MRO::Compat |
75 | *check_package_cache_flag = \&mro::get_pkg_gen; |
76 | |
77 | # now try and load the Sub::Name |
78 | # module and use that as a means |
79 | # for naming our CVs, if not, we |
80 | # use the workaround instead. |
81 | if ( eval { require Sub::Name } ) { |
6c34db07 |
82 | *subname = \&Sub::Name::subname; |
4c105333 |
83 | } |
84 | else { |
85 | *subname = $_PP_subname; |
86 | } |
87 | } |
b1f5f41d |
88 | } |
e0e4674a |
89 | |
be7677c7 |
90 | { |
91 | # Metaclasses are singletons, so we cache them here. |
92 | # there is no need to worry about destruction though |
93 | # because they should die only when the program dies. |
94 | # After all, do package definitions even get reaped? |
1d68af04 |
95 | my %METAS; |
96 | |
97 | # means of accessing all the metaclasses that have |
be7677c7 |
98 | # been initialized thus far (for mugwumps obj browser) |
1d68af04 |
99 | sub get_all_metaclasses { %METAS } |
100 | sub get_all_metaclass_instances { values %METAS } |
101 | sub get_all_metaclass_names { keys %METAS } |
be7677c7 |
102 | sub get_metaclass_by_name { $METAS{$_[0]} } |
1d68af04 |
103 | sub store_metaclass_by_name { $METAS{$_[0]} = $_[1] } |
104 | sub weaken_metaclass { weaken($METAS{$_[0]}) } |
be7677c7 |
105 | sub does_metaclass_exist { exists $METAS{$_[0]} && defined $METAS{$_[0]} } |
1d68af04 |
106 | sub remove_metaclass_by_name { $METAS{$_[0]} = undef } |
107 | |
be7677c7 |
108 | # NOTE: |
1d68af04 |
109 | # We only cache metaclasses, meaning instances of |
110 | # Class::MOP::Class. We do not cache instance of |
be7677c7 |
111 | # Class::MOP::Package or Class::MOP::Module. Mostly |
1d68af04 |
112 | # because I don't yet see a good reason to do so. |
be7677c7 |
113 | } |
114 | |
448b6e55 |
115 | sub load_class { |
116 | my $class = shift; |
ab5e2f48 |
117 | |
118 | if (ref($class) || !defined($class) || !length($class)) { |
119 | my $display = defined($class) ? $class : 'undef'; |
120 | confess "Invalid class name ($display)"; |
121 | } |
122 | |
07940968 |
123 | # if the class is not already loaded in the symbol table.. |
124 | unless (is_class_loaded($class)) { |
125 | # require it |
126 | my $file = $class . '.pm'; |
127 | $file =~ s{::}{/}g; |
128 | eval { CORE::require($file) }; |
129 | confess "Could not load class ($class) because : $@" if $@; |
130 | } |
131 | |
132 | # initialize a metaclass if necessary |
448b6e55 |
133 | unless (does_metaclass_exist($class)) { |
134 | eval { Class::MOP::Class->initialize($class) }; |
1d68af04 |
135 | confess "Could not initialize class ($class) because : $@" if $@; |
448b6e55 |
136 | } |
07940968 |
137 | |
138 | return get_metaclass_by_name($class); |
448b6e55 |
139 | } |
140 | |
141 | sub is_class_loaded { |
c1d5345a |
142 | my $class = shift; |
26fcef27 |
143 | |
144 | return 0 if ref($class) || !defined($class) || !length($class); |
145 | |
146 | # walk the symbol table tree to avoid autovififying |
147 | # \*{${main::}{"Foo::"}} == \*main::Foo:: |
148 | |
149 | my $pack = \*::; |
150 | foreach my $part (split('::', $class)) { |
151 | return 0 unless exists ${$$pack}{"${part}::"}; |
152 | $pack = \*{${$$pack}{"${part}::"}}; |
c1d5345a |
153 | } |
26fcef27 |
154 | |
155 | # check for $VERSION or @ISA |
156 | return 1 if exists ${$$pack}{VERSION} |
157 | && defined *{${$$pack}{VERSION}}{SCALAR}; |
158 | return 1 if exists ${$$pack}{ISA} |
159 | && defined *{${$$pack}{ISA}}{ARRAY}; |
160 | |
161 | # check for any method |
162 | foreach ( keys %{$$pack} ) { |
163 | next if substr($_, -2, 2) eq '::'; |
d5be3722 |
164 | |
165 | my $glob = ${$$pack}{$_} || next; |
166 | |
9e275e86 |
167 | # constant subs |
d5be3722 |
168 | if ( IS_RUNNING_ON_5_10 ) { |
169 | return 1 if ref $glob eq 'SCALAR'; |
170 | } |
171 | |
172 | return 1 if defined *{$glob}{CODE}; |
26fcef27 |
173 | } |
174 | |
175 | # fail |
c1d5345a |
176 | return 0; |
448b6e55 |
177 | } |
178 | |
179 | |
aa448b16 |
180 | ## ---------------------------------------------------------------------------- |
181 | ## Setting up our environment ... |
182 | ## ---------------------------------------------------------------------------- |
1d68af04 |
183 | ## Class::MOP needs to have a few things in the global perl environment so |
aa448b16 |
184 | ## that it can operate effectively. Those things are done here. |
185 | ## ---------------------------------------------------------------------------- |
186 | |
3bf7644b |
187 | # ... nothing yet actually ;) |
8b978dd5 |
188 | |
b51af7f9 |
189 | ## ---------------------------------------------------------------------------- |
1d68af04 |
190 | ## Bootstrapping |
b51af7f9 |
191 | ## ---------------------------------------------------------------------------- |
1d68af04 |
192 | ## The code below here is to bootstrap our MOP with itself. This is also |
b51af7f9 |
193 | ## sometimes called "tying the knot". By doing this, we make it much easier |
194 | ## to extend the MOP through subclassing and such since now you can use the |
1d68af04 |
195 | ## MOP itself to extend itself. |
196 | ## |
b51af7f9 |
197 | ## Yes, I know, thats weird and insane, but it's a good thing, trust me :) |
1d68af04 |
198 | ## ---------------------------------------------------------------------------- |
727919c5 |
199 | |
1d68af04 |
200 | # We need to add in the meta-attributes here so that |
201 | # any subclass of Class::MOP::* will be able to |
727919c5 |
202 | # inherit them using &construct_instance |
203 | |
f0480c45 |
204 | ## -------------------------------------------------------- |
6d5355c3 |
205 | ## Class::MOP::Package |
727919c5 |
206 | |
6d5355c3 |
207 | Class::MOP::Package->meta->add_attribute( |
8683db0e |
208 | Class::MOP::Attribute->new('package' => ( |
b880e0de |
209 | reader => { |
1d68af04 |
210 | # NOTE: we need to do this in order |
211 | # for the instance meta-object to |
b880e0de |
212 | # not fall into meta-circular death |
1d68af04 |
213 | # |
ce2ae40f |
214 | # we just alias the original method |
1d68af04 |
215 | # rather than re-produce it here |
ce2ae40f |
216 | 'name' => \&Class::MOP::Package::name |
b880e0de |
217 | }, |
c23184fc |
218 | init_arg => 'package', |
727919c5 |
219 | )) |
220 | ); |
221 | |
a5e51f0b |
222 | Class::MOP::Package->meta->add_attribute( |
8683db0e |
223 | Class::MOP::Attribute->new('namespace' => ( |
a5e51f0b |
224 | reader => { |
56dcfc1a |
225 | # NOTE: |
ce2ae40f |
226 | # we just alias the original method |
227 | # rather than re-produce it here |
228 | 'namespace' => \&Class::MOP::Package::namespace |
a5e51f0b |
229 | }, |
2e877f58 |
230 | init_arg => undef, |
c4260b45 |
231 | default => sub { \undef } |
a5e51f0b |
232 | )) |
233 | ); |
234 | |
9d6dce77 |
235 | # NOTE: |
236 | # use the metaclass to construct the meta-package |
237 | # which is a superclass of the metaclass itself :P |
238 | Class::MOP::Package->meta->add_method('initialize' => sub { |
239 | my $class = shift; |
240 | my $package_name = shift; |
1d68af04 |
241 | $class->meta->new_object('package' => $package_name, @_); |
9d6dce77 |
242 | }); |
243 | |
f0480c45 |
244 | ## -------------------------------------------------------- |
245 | ## Class::MOP::Module |
246 | |
247 | # NOTE: |
1d68af04 |
248 | # yeah this is kind of stretching things a bit, |
f0480c45 |
249 | # but truthfully the version should be an attribute |
1d68af04 |
250 | # of the Module, the weirdness comes from having to |
251 | # stick to Perl 5 convention and store it in the |
252 | # $VERSION package variable. Basically if you just |
253 | # squint at it, it will look how you want it to look. |
f0480c45 |
254 | # Either as a package variable, or as a attribute of |
255 | # the metaclass, isn't abstraction great :) |
256 | |
257 | Class::MOP::Module->meta->add_attribute( |
8683db0e |
258 | Class::MOP::Attribute->new('version' => ( |
f0480c45 |
259 | reader => { |
ce2ae40f |
260 | # NOTE: |
261 | # we just alias the original method |
1d68af04 |
262 | # rather than re-produce it here |
ce2ae40f |
263 | 'version' => \&Class::MOP::Module::version |
f0480c45 |
264 | }, |
2e877f58 |
265 | init_arg => undef, |
c4260b45 |
266 | default => sub { \undef } |
f0480c45 |
267 | )) |
268 | ); |
269 | |
270 | # NOTE: |
1d68af04 |
271 | # By following the same conventions as version here, |
272 | # we are opening up the possibility that people can |
273 | # use the $AUTHORITY in non-Class::MOP modules as |
274 | # well. |
f0480c45 |
275 | |
276 | Class::MOP::Module->meta->add_attribute( |
8683db0e |
277 | Class::MOP::Attribute->new('authority' => ( |
f0480c45 |
278 | reader => { |
ce2ae40f |
279 | # NOTE: |
280 | # we just alias the original method |
1d68af04 |
281 | # rather than re-produce it here |
ce2ae40f |
282 | 'authority' => \&Class::MOP::Module::authority |
1d68af04 |
283 | }, |
2e877f58 |
284 | init_arg => undef, |
c4260b45 |
285 | default => sub { \undef } |
f0480c45 |
286 | )) |
287 | ); |
288 | |
289 | ## -------------------------------------------------------- |
6d5355c3 |
290 | ## Class::MOP::Class |
291 | |
727919c5 |
292 | Class::MOP::Class->meta->add_attribute( |
8683db0e |
293 | Class::MOP::Attribute->new('attributes' => ( |
f7259199 |
294 | reader => { |
1d68af04 |
295 | # NOTE: we need to do this in order |
296 | # for the instance meta-object to |
297 | # not fall into meta-circular death |
298 | # |
ce2ae40f |
299 | # we just alias the original method |
1d68af04 |
300 | # rather than re-produce it here |
ce2ae40f |
301 | 'get_attribute_map' => \&Class::MOP::Class::get_attribute_map |
f7259199 |
302 | }, |
c23184fc |
303 | init_arg => 'attributes', |
727919c5 |
304 | default => sub { {} } |
305 | )) |
306 | ); |
307 | |
351bd7d4 |
308 | Class::MOP::Class->meta->add_attribute( |
8683db0e |
309 | Class::MOP::Attribute->new('methods' => ( |
c23184fc |
310 | init_arg => 'methods', |
1d68af04 |
311 | reader => { |
ce2ae40f |
312 | # NOTE: |
313 | # we just alias the original method |
1d68af04 |
314 | # rather than re-produce it here |
ce2ae40f |
315 | 'get_method_map' => \&Class::MOP::Class::get_method_map |
92330ee2 |
316 | }, |
7855ddba |
317 | default => sub { {} } |
c4260b45 |
318 | )) |
319 | ); |
320 | |
321 | Class::MOP::Class->meta->add_attribute( |
8683db0e |
322 | Class::MOP::Attribute->new('superclasses' => ( |
c23184fc |
323 | accessor => { |
324 | # NOTE: |
325 | # we just alias the original method |
1d68af04 |
326 | # rather than re-produce it here |
c23184fc |
327 | 'superclasses' => \&Class::MOP::Class::superclasses |
328 | }, |
2e877f58 |
329 | init_arg => undef, |
c23184fc |
330 | default => sub { \undef } |
331 | )) |
332 | ); |
333 | |
334 | Class::MOP::Class->meta->add_attribute( |
8683db0e |
335 | Class::MOP::Attribute->new('attribute_metaclass' => ( |
1d68af04 |
336 | reader => { |
6d2118a4 |
337 | # NOTE: |
338 | # we just alias the original method |
1d68af04 |
339 | # rather than re-produce it here |
6d2118a4 |
340 | 'attribute_metaclass' => \&Class::MOP::Class::attribute_metaclass |
1d68af04 |
341 | }, |
c23184fc |
342 | init_arg => 'attribute_metaclass', |
351bd7d4 |
343 | default => 'Class::MOP::Attribute', |
344 | )) |
345 | ); |
346 | |
347 | Class::MOP::Class->meta->add_attribute( |
8683db0e |
348 | Class::MOP::Attribute->new('method_metaclass' => ( |
1d68af04 |
349 | reader => { |
6d2118a4 |
350 | # NOTE: |
351 | # we just alias the original method |
1d68af04 |
352 | # rather than re-produce it here |
6d2118a4 |
353 | 'method_metaclass' => \&Class::MOP::Class::method_metaclass |
354 | }, |
c23184fc |
355 | init_arg => 'method_metaclass', |
1d68af04 |
356 | default => 'Class::MOP::Method', |
351bd7d4 |
357 | )) |
358 | ); |
359 | |
2bab2be6 |
360 | Class::MOP::Class->meta->add_attribute( |
8683db0e |
361 | Class::MOP::Attribute->new('instance_metaclass' => ( |
b880e0de |
362 | reader => { |
1d68af04 |
363 | # NOTE: we need to do this in order |
364 | # for the instance meta-object to |
365 | # not fall into meta-circular death |
366 | # |
ce2ae40f |
367 | # we just alias the original method |
1d68af04 |
368 | # rather than re-produce it here |
ce2ae40f |
369 | 'instance_metaclass' => \&Class::MOP::Class::instance_metaclass |
b880e0de |
370 | }, |
c23184fc |
371 | init_arg => 'instance_metaclass', |
1d68af04 |
372 | default => 'Class::MOP::Instance', |
2bab2be6 |
373 | )) |
374 | ); |
375 | |
9d6dce77 |
376 | # NOTE: |
1d68af04 |
377 | # we don't actually need to tie the knot with |
378 | # Class::MOP::Class here, it is actually handled |
379 | # within Class::MOP::Class itself in the |
380 | # construct_class_instance method. |
9d6dce77 |
381 | |
f0480c45 |
382 | ## -------------------------------------------------------- |
727919c5 |
383 | ## Class::MOP::Attribute |
384 | |
7b31baf4 |
385 | Class::MOP::Attribute->meta->add_attribute( |
8683db0e |
386 | Class::MOP::Attribute->new('name' => ( |
c23184fc |
387 | init_arg => 'name', |
388 | reader => { |
1d68af04 |
389 | # NOTE: we need to do this in order |
390 | # for the instance meta-object to |
391 | # not fall into meta-circular death |
392 | # |
ce2ae40f |
393 | # we just alias the original method |
1d68af04 |
394 | # rather than re-produce it here |
ce2ae40f |
395 | 'name' => \&Class::MOP::Attribute::name |
b880e0de |
396 | } |
7b31baf4 |
397 | )) |
398 | ); |
399 | |
400 | Class::MOP::Attribute->meta->add_attribute( |
8683db0e |
401 | Class::MOP::Attribute->new('associated_class' => ( |
c23184fc |
402 | init_arg => 'associated_class', |
403 | reader => { |
1d68af04 |
404 | # NOTE: we need to do this in order |
405 | # for the instance meta-object to |
406 | # not fall into meta-circular death |
407 | # |
ce2ae40f |
408 | # we just alias the original method |
1d68af04 |
409 | # rather than re-produce it here |
ce2ae40f |
410 | 'associated_class' => \&Class::MOP::Attribute::associated_class |
b880e0de |
411 | } |
7b31baf4 |
412 | )) |
413 | ); |
414 | |
415 | Class::MOP::Attribute->meta->add_attribute( |
8683db0e |
416 | Class::MOP::Attribute->new('accessor' => ( |
c23184fc |
417 | init_arg => 'accessor', |
6d2118a4 |
418 | reader => { 'accessor' => \&Class::MOP::Attribute::accessor }, |
419 | predicate => { 'has_accessor' => \&Class::MOP::Attribute::has_accessor }, |
7b31baf4 |
420 | )) |
421 | ); |
422 | |
423 | Class::MOP::Attribute->meta->add_attribute( |
8683db0e |
424 | Class::MOP::Attribute->new('reader' => ( |
c23184fc |
425 | init_arg => 'reader', |
6d2118a4 |
426 | reader => { 'reader' => \&Class::MOP::Attribute::reader }, |
427 | predicate => { 'has_reader' => \&Class::MOP::Attribute::has_reader }, |
7b31baf4 |
428 | )) |
429 | ); |
430 | |
431 | Class::MOP::Attribute->meta->add_attribute( |
8683db0e |
432 | Class::MOP::Attribute->new('initializer' => ( |
0ab65f99 |
433 | init_arg => 'initializer', |
8ee74136 |
434 | reader => { 'initializer' => \&Class::MOP::Attribute::initializer }, |
435 | predicate => { 'has_initializer' => \&Class::MOP::Attribute::has_initializer }, |
0ab65f99 |
436 | )) |
437 | ); |
438 | |
439 | Class::MOP::Attribute->meta->add_attribute( |
8683db0e |
440 | Class::MOP::Attribute->new('writer' => ( |
c23184fc |
441 | init_arg => 'writer', |
6d2118a4 |
442 | reader => { 'writer' => \&Class::MOP::Attribute::writer }, |
443 | predicate => { 'has_writer' => \&Class::MOP::Attribute::has_writer }, |
7b31baf4 |
444 | )) |
445 | ); |
446 | |
447 | Class::MOP::Attribute->meta->add_attribute( |
8683db0e |
448 | Class::MOP::Attribute->new('predicate' => ( |
c23184fc |
449 | init_arg => 'predicate', |
6d2118a4 |
450 | reader => { 'predicate' => \&Class::MOP::Attribute::predicate }, |
451 | predicate => { 'has_predicate' => \&Class::MOP::Attribute::has_predicate }, |
7b31baf4 |
452 | )) |
453 | ); |
454 | |
455 | Class::MOP::Attribute->meta->add_attribute( |
8683db0e |
456 | Class::MOP::Attribute->new('clearer' => ( |
c23184fc |
457 | init_arg => 'clearer', |
6d2118a4 |
458 | reader => { 'clearer' => \&Class::MOP::Attribute::clearer }, |
459 | predicate => { 'has_clearer' => \&Class::MOP::Attribute::has_clearer }, |
7d28758b |
460 | )) |
461 | ); |
462 | |
463 | Class::MOP::Attribute->meta->add_attribute( |
8683db0e |
464 | Class::MOP::Attribute->new('builder' => ( |
1d68af04 |
465 | init_arg => 'builder', |
466 | reader => { 'builder' => \&Class::MOP::Attribute::builder }, |
467 | predicate => { 'has_builder' => \&Class::MOP::Attribute::has_builder }, |
468 | )) |
469 | ); |
470 | |
471 | Class::MOP::Attribute->meta->add_attribute( |
8683db0e |
472 | Class::MOP::Attribute->new('init_arg' => ( |
c23184fc |
473 | init_arg => 'init_arg', |
6d2118a4 |
474 | reader => { 'init_arg' => \&Class::MOP::Attribute::init_arg }, |
475 | predicate => { 'has_init_arg' => \&Class::MOP::Attribute::has_init_arg }, |
7b31baf4 |
476 | )) |
477 | ); |
478 | |
479 | Class::MOP::Attribute->meta->add_attribute( |
8683db0e |
480 | Class::MOP::Attribute->new('default' => ( |
c23184fc |
481 | init_arg => 'default', |
7b31baf4 |
482 | # default has a custom 'reader' method ... |
1d68af04 |
483 | predicate => { 'has_default' => \&Class::MOP::Attribute::has_default }, |
7b31baf4 |
484 | )) |
485 | ); |
486 | |
3545c727 |
487 | Class::MOP::Attribute->meta->add_attribute( |
8683db0e |
488 | Class::MOP::Attribute->new('associated_methods' => ( |
c23184fc |
489 | init_arg => 'associated_methods', |
490 | reader => { 'associated_methods' => \&Class::MOP::Attribute::associated_methods }, |
1d68af04 |
491 | default => sub { [] } |
3545c727 |
492 | )) |
493 | ); |
727919c5 |
494 | |
495 | # NOTE: (meta-circularity) |
496 | # This should be one of the last things done |
497 | # it will "tie the knot" with Class::MOP::Attribute |
1d68af04 |
498 | # so that it uses the attributes meta-objects |
499 | # to construct itself. |
727919c5 |
500 | Class::MOP::Attribute->meta->add_method('new' => sub { |
649efb63 |
501 | my ( $class, @args ) = @_; |
502 | |
503 | unshift @args, "name" if @args % 2 == 1; |
504 | my %options = @args; |
505 | |
506 | my $name = $options{name}; |
1d68af04 |
507 | |
727919c5 |
508 | (defined $name && $name) |
509 | || confess "You must provide a name for the attribute"; |
1d68af04 |
510 | $options{init_arg} = $name |
5659d76e |
511 | if not exists $options{init_arg}; |
1d68af04 |
512 | |
513 | if(exists $options{builder}){ |
514 | confess("builder must be a defined scalar value which is a method name") |
515 | if ref $options{builder} || !(defined $options{builder}); |
516 | confess("Setting both default and builder is not allowed.") |
517 | if exists $options{default}; |
8fe581e5 |
518 | } else { |
519 | (Class::MOP::Attribute::is_default_a_coderef(\%options)) |
520 | || confess("References are not allowed as default values, you must ". |
3c0a8087 |
521 | "wrap the default of '$name' in a CODE reference (ex: sub { [] } and not [])") |
8fe581e5 |
522 | if exists $options{default} && ref $options{default}; |
1d68af04 |
523 | } |
8683db0e |
524 | |
5659d76e |
525 | # return the new object |
649efb63 |
526 | $class->meta->new_object(%options); |
5659d76e |
527 | }); |
528 | |
529 | Class::MOP::Attribute->meta->add_method('clone' => sub { |
a740253a |
530 | my $self = shift; |
1d68af04 |
531 | $self->meta->clone_object($self, @_); |
727919c5 |
532 | }); |
533 | |
f0480c45 |
534 | ## -------------------------------------------------------- |
b6164407 |
535 | ## Class::MOP::Method |
b6164407 |
536 | Class::MOP::Method->meta->add_attribute( |
8683db0e |
537 | Class::MOP::Attribute->new('body' => ( |
c23184fc |
538 | init_arg => 'body', |
539 | reader => { 'body' => \&Class::MOP::Method::body }, |
b6164407 |
540 | )) |
541 | ); |
542 | |
4c105333 |
543 | Class::MOP::Method->meta->add_attribute( |
8683db0e |
544 | Class::MOP::Attribute->new('package_name' => ( |
4c105333 |
545 | init_arg => 'package_name', |
546 | reader => { 'package_name' => \&Class::MOP::Method::package_name }, |
547 | )) |
548 | ); |
549 | |
550 | Class::MOP::Method->meta->add_attribute( |
8683db0e |
551 | Class::MOP::Attribute->new('name' => ( |
4c105333 |
552 | init_arg => 'name', |
553 | reader => { 'name' => \&Class::MOP::Method::name }, |
554 | )) |
555 | ); |
556 | |
557 | Class::MOP::Method->meta->add_method('wrap' => sub { |
5caf45ce |
558 | my ( $class, @args ) = @_; |
559 | |
560 | unshift @args, 'body' if @args % 2 == 1; |
561 | |
562 | my %options = @args; |
563 | my $code = $options{body}; |
4c105333 |
564 | |
9b522fc4 |
565 | ('CODE' eq ref($code)) |
4c105333 |
566 | || confess "You must supply a CODE reference to bless, not (" . ($code || 'undef') . ")"; |
567 | |
b38f3848 |
568 | ($options{package_name} && $options{name}) |
569 | || confess "You must supply the package_name and name parameters"; |
570 | |
4c105333 |
571 | # return the new object |
5caf45ce |
572 | $class->meta->new_object(%options); |
4c105333 |
573 | }); |
574 | |
575 | Class::MOP::Method->meta->add_method('clone' => sub { |
576 | my $self = shift; |
577 | $self->meta->clone_object($self, @_); |
578 | }); |
579 | |
b6164407 |
580 | ## -------------------------------------------------------- |
581 | ## Class::MOP::Method::Wrapped |
582 | |
583 | # NOTE: |
1d68af04 |
584 | # the way this item is initialized, this |
585 | # really does not follow the standard |
586 | # practices of attributes, but we put |
b6164407 |
587 | # it here for completeness |
588 | Class::MOP::Method::Wrapped->meta->add_attribute( |
8683db0e |
589 | Class::MOP::Attribute->new('modifier_table') |
b6164407 |
590 | ); |
591 | |
592 | ## -------------------------------------------------------- |
565f0cbb |
593 | ## Class::MOP::Method::Generated |
594 | |
595 | Class::MOP::Method::Generated->meta->add_attribute( |
8683db0e |
596 | Class::MOP::Attribute->new('is_inline' => ( |
565f0cbb |
597 | init_arg => 'is_inline', |
598 | reader => { 'is_inline' => \&Class::MOP::Method::Generated::is_inline }, |
4c105333 |
599 | default => 0, |
1d68af04 |
600 | )) |
565f0cbb |
601 | ); |
602 | |
4c105333 |
603 | Class::MOP::Method::Generated->meta->add_method('new' => sub { |
604 | my ($class, %options) = @_; |
b38f3848 |
605 | ($options{package_name} && $options{name}) |
606 | || confess "You must supply the package_name and name parameters"; |
4c105333 |
607 | my $self = $class->meta->new_object(%options); |
608 | $self->initialize_body; |
609 | $self; |
610 | }); |
611 | |
565f0cbb |
612 | ## -------------------------------------------------------- |
d90b42a6 |
613 | ## Class::MOP::Method::Accessor |
614 | |
615 | Class::MOP::Method::Accessor->meta->add_attribute( |
8683db0e |
616 | Class::MOP::Attribute->new('attribute' => ( |
c23184fc |
617 | init_arg => 'attribute', |
1d68af04 |
618 | reader => { |
619 | 'associated_attribute' => \&Class::MOP::Method::Accessor::associated_attribute |
d90b42a6 |
620 | }, |
1d68af04 |
621 | )) |
d90b42a6 |
622 | ); |
623 | |
624 | Class::MOP::Method::Accessor->meta->add_attribute( |
8683db0e |
625 | Class::MOP::Attribute->new('accessor_type' => ( |
c23184fc |
626 | init_arg => 'accessor_type', |
627 | reader => { 'accessor_type' => \&Class::MOP::Method::Accessor::accessor_type }, |
1d68af04 |
628 | )) |
d90b42a6 |
629 | ); |
630 | |
4c105333 |
631 | Class::MOP::Method::Accessor->meta->add_method('new' => sub { |
632 | my $class = shift; |
633 | my %options = @_; |
634 | |
635 | (exists $options{attribute}) |
636 | || confess "You must supply an attribute to construct with"; |
637 | |
638 | (exists $options{accessor_type}) |
639 | || confess "You must supply an accessor_type to construct with"; |
640 | |
641 | (Scalar::Util::blessed($options{attribute}) && $options{attribute}->isa('Class::MOP::Attribute')) |
642 | || confess "You must supply an attribute which is a 'Class::MOP::Attribute' instance"; |
643 | |
b38f3848 |
644 | ($options{package_name} && $options{name}) |
645 | || confess "You must supply the package_name and name parameters"; |
646 | |
4c105333 |
647 | # return the new object |
648 | my $self = $class->meta->new_object(%options); |
649 | |
650 | # we don't want this creating |
651 | # a cycle in the code, if not |
652 | # needed |
8683db0e |
653 | Scalar::Util::weaken($self->{'attribute'}); |
4c105333 |
654 | |
655 | $self->initialize_body; |
656 | |
657 | $self; |
658 | }); |
659 | |
d90b42a6 |
660 | |
661 | ## -------------------------------------------------------- |
662 | ## Class::MOP::Method::Constructor |
663 | |
664 | Class::MOP::Method::Constructor->meta->add_attribute( |
8683db0e |
665 | Class::MOP::Attribute->new('options' => ( |
c23184fc |
666 | init_arg => 'options', |
1d68af04 |
667 | reader => { |
668 | 'options' => \&Class::MOP::Method::Constructor::options |
d90b42a6 |
669 | }, |
4c105333 |
670 | default => sub { +{} } |
1d68af04 |
671 | )) |
d90b42a6 |
672 | ); |
673 | |
674 | Class::MOP::Method::Constructor->meta->add_attribute( |
8683db0e |
675 | Class::MOP::Attribute->new('associated_metaclass' => ( |
c23184fc |
676 | init_arg => 'metaclass', |
1d68af04 |
677 | reader => { |
678 | 'associated_metaclass' => \&Class::MOP::Method::Constructor::associated_metaclass |
679 | }, |
680 | )) |
d90b42a6 |
681 | ); |
682 | |
4c105333 |
683 | Class::MOP::Method::Constructor->meta->add_method('new' => sub { |
684 | my $class = shift; |
685 | my %options = @_; |
686 | |
687 | (Scalar::Util::blessed $options{metaclass} && $options{metaclass}->isa('Class::MOP::Class')) |
688 | || confess "You must pass a metaclass instance if you want to inline" |
689 | if $options{is_inline}; |
690 | |
b38f3848 |
691 | ($options{package_name} && $options{name}) |
692 | || confess "You must supply the package_name and name parameters"; |
693 | |
4c105333 |
694 | # return the new object |
695 | my $self = $class->meta->new_object(%options); |
696 | |
697 | # we don't want this creating |
698 | # a cycle in the code, if not |
699 | # needed |
8683db0e |
700 | Scalar::Util::weaken($self->{'associated_metaclass'}); |
4c105333 |
701 | |
702 | $self->initialize_body; |
703 | |
704 | $self; |
705 | }); |
706 | |
d90b42a6 |
707 | ## -------------------------------------------------------- |
86482605 |
708 | ## Class::MOP::Instance |
709 | |
710 | # NOTE: |
1d68af04 |
711 | # these don't yet do much of anything, but are just |
86482605 |
712 | # included for completeness |
713 | |
714 | Class::MOP::Instance->meta->add_attribute( |
63d08a9e |
715 | Class::MOP::Attribute->new('associated_metaclass') |
86482605 |
716 | ); |
717 | |
718 | Class::MOP::Instance->meta->add_attribute( |
32bfc810 |
719 | Class::MOP::Attribute->new('attributes') |
720 | ); |
721 | |
722 | Class::MOP::Instance->meta->add_attribute( |
8683db0e |
723 | Class::MOP::Attribute->new('slots') |
86482605 |
724 | ); |
725 | |
63d08a9e |
726 | Class::MOP::Instance->meta->add_attribute( |
727 | Class::MOP::Attribute->new('slot_hash') |
728 | ); |
729 | |
730 | |
caa051fa |
731 | # we need the meta instance of the meta instance to be created now, in order |
732 | # for the constructor to be able to use it |
733 | Class::MOP::Instance->meta->get_meta_instance; |
734 | |
735 | Class::MOP::Instance->meta->add_method('new' => sub { |
736 | my $class = shift; |
737 | my $options = $class->BUILDARGS(@_); |
738 | |
739 | my $self = $class->meta->new_object(%$options); |
740 | |
741 | Scalar::Util::weaken($self->{'associated_metaclass'}); |
742 | |
743 | $self; |
744 | }); |
745 | |
746 | # pretend the add_method never happenned. it hasn't yet affected anything |
747 | undef Class::MOP::Instance->meta->{_package_cache_flag}; |
748 | |
86482605 |
749 | ## -------------------------------------------------------- |
f0480c45 |
750 | ## Now close all the Class::MOP::* classes |
4d47b77f |
751 | |
0b9372a2 |
752 | # NOTE: |
1d68af04 |
753 | # we don't need to inline the |
754 | # constructors or the accessors |
755 | # this only lengthens the compile |
756 | # time of the MOP, and gives us |
0b9372a2 |
757 | # no actual benefits. |
758 | |
759 | $_->meta->make_immutable( |
760 | inline_constructor => 0, |
761 | inline_accessors => 0, |
762 | ) for qw/ |
1d68af04 |
763 | Class::MOP::Package |
764 | Class::MOP::Module |
765 | Class::MOP::Class |
766 | |
0b9372a2 |
767 | Class::MOP::Attribute |
1d68af04 |
768 | Class::MOP::Method |
769 | Class::MOP::Instance |
770 | |
771 | Class::MOP::Object |
0b9372a2 |
772 | |
565f0cbb |
773 | Class::MOP::Method::Generated |
1d68af04 |
774 | |
ba38bf08 |
775 | Class::MOP::Method::Accessor |
1d68af04 |
776 | Class::MOP::Method::Constructor |
777 | Class::MOP::Method::Wrapped |
0b9372a2 |
778 | /; |
b6164407 |
779 | |
94b19069 |
780 | 1; |
781 | |
782 | __END__ |
783 | |
784 | =pod |
785 | |
1d68af04 |
786 | =head1 NAME |
94b19069 |
787 | |
788 | Class::MOP - A Meta Object Protocol for Perl 5 |
789 | |
94b19069 |
790 | =head1 DESCRIPTON |
791 | |
127d39a7 |
792 | This module is a fully functioning meta object protocol for the |
1d68af04 |
793 | Perl 5 object system. It makes no attempt to change the behavior or |
794 | characteristics of the Perl 5 object system, only to create a |
27e31eaf |
795 | protocol for its manipulation and introspection. |
94b19069 |
796 | |
1d68af04 |
797 | That said, it does attempt to create the tools for building a rich |
798 | set of extensions to the Perl 5 object system. Every attempt has been |
799 | made for these tools to keep to the spirit of the Perl 5 object |
94b19069 |
800 | system that we all know and love. |
801 | |
1d68af04 |
802 | This documentation is admittedly sparse on details, as time permits |
803 | I will try to improve them. For now, I suggest looking at the items |
804 | listed in the L<SEE ALSO> section for more information. In particular |
805 | the book "The Art of the Meta Object Protocol" was very influential |
40483095 |
806 | in the development of this system. |
807 | |
bfe4d0fc |
808 | =head2 What is a Meta Object Protocol? |
809 | |
1d68af04 |
810 | A meta object protocol is an API to an object system. |
bfe4d0fc |
811 | |
1d68af04 |
812 | To be more specific, it is a set of abstractions of the components of |
813 | an object system (typically things like; classes, object, methods, |
814 | object attributes, etc.). These abstractions can then be used to both |
bfe4d0fc |
815 | inspect and manipulate the object system which they describe. |
816 | |
1d68af04 |
817 | It can be said that there are two MOPs for any object system; the |
818 | implicit MOP, and the explicit MOP. The implicit MOP handles things |
819 | like method dispatch or inheritance, which happen automatically as |
820 | part of how the object system works. The explicit MOP typically |
821 | handles the introspection/reflection features of the object system. |
822 | All object systems have implicit MOPs, without one, they would not |
823 | work. Explict MOPs however as less common, and depending on the |
824 | language can vary from restrictive (Reflection in Java or C#) to |
825 | wide open (CLOS is a perfect example). |
bfe4d0fc |
826 | |
e16da3e6 |
827 | =head2 Yet Another Class Builder!! Why? |
828 | |
1d68af04 |
829 | This is B<not> a class builder so much as it is a I<class builder |
830 | B<builder>>. My intent is that an end user does not use this module |
831 | directly, but instead this module is used by module authors to |
832 | build extensions and features onto the Perl 5 object system. |
e16da3e6 |
833 | |
94b19069 |
834 | =head2 Who is this module for? |
835 | |
1d68af04 |
836 | This module is specifically for anyone who has ever created or |
837 | wanted to create a module for the Class:: namespace. The tools which |
838 | this module will provide will hopefully make it easier to do more |
839 | complex things with Perl 5 classes by removing such barriers as |
840 | the need to hack the symbol tables, or understand the fine details |
841 | of method dispatch. |
94b19069 |
842 | |
bfe4d0fc |
843 | =head2 What changes do I have to make to use this module? |
844 | |
1d68af04 |
845 | This module was designed to be as unintrusive as possible. Many of |
846 | its features are accessible without B<any> change to your existsing |
847 | code at all. It is meant to be a compliment to your existing code and |
848 | not an intrusion on your code base. Unlike many other B<Class::> |
849 | modules, this module B<does not> require you subclass it, or even that |
850 | you C<use> it in within your module's package. |
bfe4d0fc |
851 | |
1d68af04 |
852 | The only features which requires additions to your code are the |
2eb717d5 |
853 | attribute handling and instance construction features, and these are |
1d68af04 |
854 | both completely optional features. The only reason for this is because |
855 | Perl 5's object system does not actually have these features built |
2eb717d5 |
856 | in. More information about this feature can be found below. |
bfe4d0fc |
857 | |
858 | =head2 A Note about Performance? |
859 | |
1d68af04 |
860 | It is a common misconception that explict MOPs are performance drains. |
861 | But this is not a universal truth at all, it is an side-effect of |
862 | specific implementations. For instance, using Java reflection is much |
863 | slower because the JVM cannot take advantage of any compiler |
864 | optimizations, and the JVM has to deal with much more runtime type |
865 | information as well. Reflection in C# is marginally better as it was |
866 | designed into the language and runtime (the CLR). In contrast, CLOS |
867 | (the Common Lisp Object System) was built to support an explicit MOP, |
868 | and so performance is tuned for it. |
869 | |
870 | This library in particular does it's absolute best to avoid putting |
871 | B<any> drain at all upon your code's performance. In fact, by itself |
872 | it does nothing to affect your existing code. So you only pay for |
2eb717d5 |
873 | what you actually use. |
bfe4d0fc |
874 | |
550d56db |
875 | =head2 About Metaclass compatibility |
876 | |
1d68af04 |
877 | This module makes sure that all metaclasses created are both upwards |
878 | and downwards compatible. The topic of metaclass compatibility is |
879 | highly esoteric and is something only encountered when doing deep and |
880 | involved metaclass hacking. There are two basic kinds of metaclass |
881 | incompatibility; upwards and downwards. |
550d56db |
882 | |
1d68af04 |
883 | Upwards metaclass compatibility means that the metaclass of a |
884 | given class is either the same as (or a subclass of) all of the |
550d56db |
885 | class's ancestors. |
886 | |
1d68af04 |
887 | Downward metaclass compatibility means that the metaclasses of a |
888 | given class's anscestors are all either the same as (or a subclass |
550d56db |
889 | of) that metaclass. |
890 | |
1d68af04 |
891 | Here is a diagram showing a set of two classes (C<A> and C<B>) and |
892 | two metaclasses (C<Meta::A> and C<Meta::B>) which have correct |
550d56db |
893 | metaclass compatibility both upwards and downwards. |
894 | |
895 | +---------+ +---------+ |
896 | | Meta::A |<----| Meta::B | <....... (instance of ) |
1d68af04 |
897 | +---------+ +---------+ <------- (inherits from) |
550d56db |
898 | ^ ^ |
899 | : : |
900 | +---------+ +---------+ |
901 | | A |<----| B | |
902 | +---------+ +---------+ |
903 | |
1d68af04 |
904 | As I said this is a highly esoteric topic and one you will only run |
905 | into if you do a lot of subclassing of B<Class::MOP::Class>. If you |
906 | are interested in why this is an issue see the paper |
907 | I<Uniform and safe metaclass composition> linked to in the |
550d56db |
908 | L<SEE ALSO> section of this document. |
909 | |
aa448b16 |
910 | =head2 Using custom metaclasses |
911 | |
1d68af04 |
912 | Always use the metaclass pragma when using a custom metaclass, this |
913 | will ensure the proper initialization order and not accidentely |
914 | create an incorrect type of metaclass for you. This is a very rare |
915 | problem, and one which can only occur if you are doing deep metaclass |
aa448b16 |
916 | programming. So in other words, don't worry about it. |
917 | |
94b19069 |
918 | =head1 PROTOCOLS |
919 | |
127d39a7 |
920 | The protocol is divided into 4 main sub-protocols: |
94b19069 |
921 | |
922 | =over 4 |
923 | |
924 | =item The Class protocol |
925 | |
1d68af04 |
926 | This provides a means of manipulating and introspecting a Perl 5 |
927 | class. It handles all of symbol table hacking for you, and provides |
94b19069 |
928 | a rich set of methods that go beyond simple package introspection. |
929 | |
552e3d24 |
930 | See L<Class::MOP::Class> for more details. |
931 | |
94b19069 |
932 | =item The Attribute protocol |
933 | |
1d68af04 |
934 | This provides a consistent represenation for an attribute of a |
935 | Perl 5 class. Since there are so many ways to create and handle |
127d39a7 |
936 | attributes in Perl 5 OO, this attempts to provide as much of a |
1d68af04 |
937 | unified approach as possible, while giving the freedom and |
94b19069 |
938 | flexibility to subclass for specialization. |
939 | |
552e3d24 |
940 | See L<Class::MOP::Attribute> for more details. |
941 | |
94b19069 |
942 | =item The Method protocol |
943 | |
1d68af04 |
944 | This provides a means of manipulating and introspecting methods in |
945 | the Perl 5 object system. As with attributes, there are many ways to |
946 | approach this topic, so we try to keep it pretty basic, while still |
94b19069 |
947 | making it possible to extend the system in many ways. |
948 | |
552e3d24 |
949 | See L<Class::MOP::Method> for more details. |
94b19069 |
950 | |
127d39a7 |
951 | =item The Instance protocol |
952 | |
953 | This provides a layer of abstraction for creating object instances. |
954 | Since the other layers use this protocol, it is relatively easy to |
955 | change the type of your instances from the default HASH ref to other |
956 | types of references. Several examples are provided in the F<examples/> |
957 | directory included in this distribution. |
958 | |
959 | See L<Class::MOP::Instance> for more details. |
960 | |
94b19069 |
961 | =back |
962 | |
be7677c7 |
963 | =head1 FUNCTIONS |
964 | |
c1d5345a |
965 | =head2 Constants |
966 | |
967 | =over 4 |
968 | |
969 | =item I<IS_RUNNING_ON_5_10> |
970 | |
971 | We set this constant depending on what version perl we are on, this |
972 | allows us to take advantage of new 5.10 features and stay backwards |
973 | compat. |
974 | |
975 | =back |
976 | |
448b6e55 |
977 | =head2 Utility functions |
978 | |
979 | =over 4 |
980 | |
981 | =item B<load_class ($class_name)> |
982 | |
1d68af04 |
983 | This will load a given C<$class_name> and if it does not have an |
448b6e55 |
984 | already initialized metaclass, then it will intialize one for it. |
127d39a7 |
985 | This function can be used in place of tricks like |
986 | C<eval "use $module"> or using C<require>. |
448b6e55 |
987 | |
988 | =item B<is_class_loaded ($class_name)> |
989 | |
1d68af04 |
990 | This will return a boolean depending on if the C<$class_name> has |
991 | been loaded. |
448b6e55 |
992 | |
1d68af04 |
993 | NOTE: This does a basic check of the symbol table to try and |
448b6e55 |
994 | determine as best it can if the C<$class_name> is loaded, it |
1d68af04 |
995 | is probably correct about 99% of the time. |
448b6e55 |
996 | |
b1f5f41d |
997 | =item B<check_package_cache_flag ($pkg)> |
e0e4674a |
998 | |
127d39a7 |
999 | This will return an integer that is managed by C<Class::MOP::Class> |
1000 | to determine if a module's symbol table has been altered. |
1001 | |
1002 | In Perl 5.10 or greater, this flag is package specific. However in |
1003 | versions prior to 5.10, this will use the C<PL_sub_generation> variable |
1004 | which is not package specific. |
1005 | |
e0e4674a |
1006 | =item B<get_code_info ($code)> |
1007 | |
127d39a7 |
1008 | This function returns two values, the name of the package the C<$code> |
1009 | is from and the name of the C<$code> itself. This is used by several |
1010 | elements of the MOP to detemine where a given C<$code> reference is from. |
1011 | |
4c105333 |
1012 | =item B<subname ($name, $code)> |
1013 | |
1014 | B<NOTE: DO NOT USE THIS FUNCTION, IT IS FOR INTERNAL USE ONLY!> |
1015 | |
1016 | If possible, we will load the L<Sub::Name> module and this will function |
1017 | as C<Sub::Name::subname> does, otherwise it will just return the C<$code> |
1018 | argument. |
1019 | |
448b6e55 |
1020 | =back |
1021 | |
1022 | =head2 Metaclass cache functions |
1023 | |
1d68af04 |
1024 | Class::MOP holds a cache of metaclasses, the following are functions |
1025 | (B<not methods>) which can be used to access that cache. It is not |
1026 | recommended that you mess with this, bad things could happen. But if |
be7677c7 |
1027 | you are brave and willing to risk it, go for it. |
1028 | |
1029 | =over 4 |
1030 | |
1031 | =item B<get_all_metaclasses> |
1032 | |
1d68af04 |
1033 | This will return an hash of all the metaclass instances that have |
1034 | been cached by B<Class::MOP::Class> keyed by the package name. |
b9d9fc0b |
1035 | |
be7677c7 |
1036 | =item B<get_all_metaclass_instances> |
1037 | |
1d68af04 |
1038 | This will return an array of all the metaclass instances that have |
b9d9fc0b |
1039 | been cached by B<Class::MOP::Class>. |
1040 | |
be7677c7 |
1041 | =item B<get_all_metaclass_names> |
1042 | |
1d68af04 |
1043 | This will return an array of all the metaclass names that have |
b9d9fc0b |
1044 | been cached by B<Class::MOP::Class>. |
1045 | |
be7677c7 |
1046 | =item B<get_metaclass_by_name ($name)> |
1047 | |
127d39a7 |
1048 | This will return a cached B<Class::MOP::Class> instance of nothing |
1049 | if no metaclass exist by that C<$name>. |
1050 | |
be7677c7 |
1051 | =item B<store_metaclass_by_name ($name, $meta)> |
1052 | |
127d39a7 |
1053 | This will store a metaclass in the cache at the supplied C<$key>. |
1054 | |
be7677c7 |
1055 | =item B<weaken_metaclass ($name)> |
1056 | |
127d39a7 |
1057 | In rare cases it is desireable to store a weakened reference in |
1058 | the metaclass cache. This function will weaken the reference to |
1059 | the metaclass stored in C<$name>. |
1060 | |
be7677c7 |
1061 | =item B<does_metaclass_exist ($name)> |
1062 | |
127d39a7 |
1063 | This will return true of there exists a metaclass stored in the |
1064 | C<$name> key and return false otherwise. |
1065 | |
be7677c7 |
1066 | =item B<remove_metaclass_by_name ($name)> |
1067 | |
127d39a7 |
1068 | This will remove a the metaclass stored in the C<$name> key. |
1069 | |
be7677c7 |
1070 | =back |
1071 | |
552e3d24 |
1072 | =head1 SEE ALSO |
8b978dd5 |
1073 | |
552e3d24 |
1074 | =head2 Books |
8b978dd5 |
1075 | |
1d68af04 |
1076 | There are very few books out on Meta Object Protocols and Metaclasses |
1077 | because it is such an esoteric topic. The following books are really |
1078 | the only ones I have found. If you know of any more, B<I<please>> |
a2e85e6c |
1079 | email me and let me know, I would love to hear about them. |
1080 | |
8b978dd5 |
1081 | =over 4 |
1082 | |
552e3d24 |
1083 | =item "The Art of the Meta Object Protocol" |
8b978dd5 |
1084 | |
552e3d24 |
1085 | =item "Advances in Object-Oriented Metalevel Architecture and Reflection" |
8b978dd5 |
1086 | |
b51af7f9 |
1087 | =item "Putting MetaClasses to Work" |
1088 | |
a2e85e6c |
1089 | =item "Smalltalk: The Language" |
1090 | |
94b19069 |
1091 | =back |
1092 | |
550d56db |
1093 | =head2 Papers |
1094 | |
1095 | =over 4 |
1096 | |
1097 | =item Uniform and safe metaclass composition |
1098 | |
1d68af04 |
1099 | An excellent paper by the people who brought us the original Traits paper. |
1100 | This paper is on how Traits can be used to do safe metaclass composition, |
1101 | and offers an excellent introduction section which delves into the topic of |
550d56db |
1102 | metaclass compatibility. |
1103 | |
1104 | L<http://www.iam.unibe.ch/~scg/Archive/Papers/Duca05ySafeMetaclassTrait.pdf> |
1105 | |
1106 | =item Safe Metaclass Programming |
1107 | |
1d68af04 |
1108 | This paper seems to precede the above paper, and propose a mix-in based |
1109 | approach as opposed to the Traits based approach. Both papers have similar |
1110 | information on the metaclass compatibility problem space. |
550d56db |
1111 | |
1112 | L<http://citeseer.ist.psu.edu/37617.html> |
1113 | |
1114 | =back |
1115 | |
552e3d24 |
1116 | =head2 Prior Art |
8b978dd5 |
1117 | |
1118 | =over 4 |
1119 | |
7184ca14 |
1120 | =item The Perl 6 MetaModel work in the Pugs project |
8b978dd5 |
1121 | |
1122 | =over 4 |
1123 | |
552e3d24 |
1124 | =item L<http://svn.openfoundry.org/pugs/perl5/Perl6-MetaModel> |
8b978dd5 |
1125 | |
552e3d24 |
1126 | =item L<http://svn.openfoundry.org/pugs/perl5/Perl6-ObjectSpace> |
8b978dd5 |
1127 | |
1128 | =back |
1129 | |
94b19069 |
1130 | =back |
1131 | |
1d68af04 |
1132 | =head2 Articles |
f8dfcfb7 |
1133 | |
1134 | =over 4 |
1135 | |
1d68af04 |
1136 | =item CPAN Module Review of Class::MOP |
f8dfcfb7 |
1137 | |
1138 | L<http://www.oreillynet.com/onlamp/blog/2006/06/cpan_module_review_classmop.html> |
1139 | |
1140 | =back |
1141 | |
a2e85e6c |
1142 | =head1 SIMILAR MODULES |
1143 | |
1d68af04 |
1144 | As I have said above, this module is a class-builder-builder, so it is |
1145 | not the same thing as modules like L<Class::Accessor> and |
1146 | L<Class::MethodMaker>. That being said there are very few modules on CPAN |
1147 | with similar goals to this module. The one I have found which is most |
1148 | like this module is L<Class::Meta>, although it's philosophy and the MOP it |
1149 | creates are very different from this modules. |
94b19069 |
1150 | |
a2e85e6c |
1151 | =head1 BUGS |
1152 | |
1d68af04 |
1153 | All complex software has bugs lurking in it, and this module is no |
a2e85e6c |
1154 | exception. If you find a bug please either email me, or add the bug |
1155 | to cpan-RT. |
1156 | |
1157 | =head1 ACKNOWLEDGEMENTS |
1158 | |
1159 | =over 4 |
1160 | |
b9d9fc0b |
1161 | =item Rob Kinyon |
a2e85e6c |
1162 | |
1d68af04 |
1163 | Thanks to Rob for actually getting the development of this module kick-started. |
a2e85e6c |
1164 | |
1165 | =back |
1166 | |
1a09d9cc |
1167 | =head1 AUTHORS |
94b19069 |
1168 | |
a2e85e6c |
1169 | Stevan Little E<lt>stevan@iinteractive.comE<gt> |
552e3d24 |
1170 | |
9c8cda90 |
1171 | B<with contributions from:> |
1172 | |
1173 | Brandon (blblack) Black |
1174 | |
1175 | Guillermo (groditi) Roditi |
1176 | |
9195ddff |
1177 | Matt (mst) Trout |
1178 | |
9c8cda90 |
1179 | Rob (robkinyon) Kinyon |
1180 | |
1181 | Yuval (nothingmuch) Kogman |
1a09d9cc |
1182 | |
f430cfa4 |
1183 | Scott (konobi) McWhirter |
1184 | |
94b19069 |
1185 | =head1 COPYRIGHT AND LICENSE |
1186 | |
69e3ab0a |
1187 | Copyright 2006-2008 by Infinity Interactive, Inc. |
94b19069 |
1188 | |
1189 | L<http://www.iinteractive.com> |
1190 | |
1191 | This library is free software; you can redistribute it and/or modify |
1d68af04 |
1192 | it under the same terms as Perl itself. |
94b19069 |
1193 | |
1194 | =cut |