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 | |
857f87a7 |
14 | use Class::MOP::Class::Immutable; |
15 | |
c4260b45 |
16 | our $VERSION = '0.34'; |
f0480c45 |
17 | our $AUTHORITY = 'cpan:STEVAN'; |
94b19069 |
18 | |
be7677c7 |
19 | { |
20 | # Metaclasses are singletons, so we cache them here. |
21 | # there is no need to worry about destruction though |
22 | # because they should die only when the program dies. |
23 | # After all, do package definitions even get reaped? |
24 | my %METAS; |
25 | |
26 | # means of accessing all the metaclasses that have |
27 | # been initialized thus far (for mugwumps obj browser) |
28 | sub get_all_metaclasses { %METAS } |
29 | sub get_all_metaclass_instances { values %METAS } |
30 | sub get_all_metaclass_names { keys %METAS } |
31 | sub get_metaclass_by_name { $METAS{$_[0]} } |
32 | sub store_metaclass_by_name { $METAS{$_[0]} = $_[1] } |
33 | sub weaken_metaclass { weaken($METAS{$_[0]}) } |
34 | sub does_metaclass_exist { exists $METAS{$_[0]} && defined $METAS{$_[0]} } |
35 | sub remove_metaclass_by_name { $METAS{$_[0]} = undef } |
36 | |
37 | # NOTE: |
38 | # We only cache metaclasses, meaning instances of |
39 | # Class::MOP::Class. We do not cache instance of |
40 | # Class::MOP::Package or Class::MOP::Module. Mostly |
41 | # because I don't yet see a good reason to do so. |
42 | } |
43 | |
aa448b16 |
44 | ## ---------------------------------------------------------------------------- |
45 | ## Setting up our environment ... |
46 | ## ---------------------------------------------------------------------------- |
47 | ## Class::MOP needs to have a few things in the global perl environment so |
48 | ## that it can operate effectively. Those things are done here. |
49 | ## ---------------------------------------------------------------------------- |
50 | |
3bf7644b |
51 | # ... nothing yet actually ;) |
8b978dd5 |
52 | |
b51af7f9 |
53 | ## ---------------------------------------------------------------------------- |
54 | ## Bootstrapping |
55 | ## ---------------------------------------------------------------------------- |
56 | ## The code below here is to bootstrap our MOP with itself. This is also |
57 | ## sometimes called "tying the knot". By doing this, we make it much easier |
58 | ## to extend the MOP through subclassing and such since now you can use the |
59 | ## MOP itself to extend itself. |
60 | ## |
61 | ## Yes, I know, thats weird and insane, but it's a good thing, trust me :) |
62 | ## ---------------------------------------------------------------------------- |
727919c5 |
63 | |
64 | # We need to add in the meta-attributes here so that |
65 | # any subclass of Class::MOP::* will be able to |
66 | # inherit them using &construct_instance |
67 | |
f0480c45 |
68 | ## -------------------------------------------------------- |
6d5355c3 |
69 | ## Class::MOP::Package |
727919c5 |
70 | |
6d5355c3 |
71 | Class::MOP::Package->meta->add_attribute( |
351bd7d4 |
72 | Class::MOP::Attribute->new('$:package' => ( |
b880e0de |
73 | reader => { |
74 | # NOTE: we need to do this in order |
75 | # for the instance meta-object to |
76 | # not fall into meta-circular death |
77 | 'name' => sub { (shift)->{'$:package'} } |
78 | }, |
7b31baf4 |
79 | init_arg => ':package', |
727919c5 |
80 | )) |
81 | ); |
82 | |
a5e51f0b |
83 | Class::MOP::Package->meta->add_attribute( |
84 | Class::MOP::Attribute->new('%:namespace' => ( |
85 | reader => { |
56dcfc1a |
86 | # NOTE: |
87 | # because of issues with the Perl API |
88 | # to the typeglob in some versions, we |
89 | # need to just always grab a new |
90 | # reference to the hash here. Ideally |
91 | # we could just store a ref and it would |
92 | # Just Work, but oh well :\ |
93 | 'namespace' => sub { |
94 | no strict 'refs'; |
95 | \%{$_[0]->name . '::'} |
96 | } |
a5e51f0b |
97 | }, |
98 | # NOTE: |
99 | # protect this from silliness |
a2ee6c61 |
100 | init_arg => '!............( DO NOT DO THIS )............!', |
c4260b45 |
101 | default => sub { \undef } |
a5e51f0b |
102 | )) |
103 | ); |
104 | |
9d6dce77 |
105 | # NOTE: |
106 | # use the metaclass to construct the meta-package |
107 | # which is a superclass of the metaclass itself :P |
108 | Class::MOP::Package->meta->add_method('initialize' => sub { |
109 | my $class = shift; |
110 | my $package_name = shift; |
111 | $class->meta->new_object(':package' => $package_name, @_); |
112 | }); |
113 | |
f0480c45 |
114 | ## -------------------------------------------------------- |
115 | ## Class::MOP::Module |
116 | |
117 | # NOTE: |
118 | # yeah this is kind of stretching things a bit, |
119 | # but truthfully the version should be an attribute |
120 | # of the Module, the weirdness comes from having to |
121 | # stick to Perl 5 convention and store it in the |
122 | # $VERSION package variable. Basically if you just |
123 | # squint at it, it will look how you want it to look. |
124 | # Either as a package variable, or as a attribute of |
125 | # the metaclass, isn't abstraction great :) |
126 | |
127 | Class::MOP::Module->meta->add_attribute( |
128 | Class::MOP::Attribute->new('$:version' => ( |
129 | reader => { |
130 | 'version' => sub { |
131 | my $self = shift; |
132 | ${$self->get_package_symbol('$VERSION')}; |
133 | } |
134 | }, |
135 | # NOTE: |
136 | # protect this from silliness |
137 | init_arg => '!............( DO NOT DO THIS )............!', |
c4260b45 |
138 | default => sub { \undef } |
f0480c45 |
139 | )) |
140 | ); |
141 | |
142 | # NOTE: |
143 | # By following the same conventions as version here, |
144 | # we are opening up the possibility that people can |
145 | # use the $AUTHORITY in non-Class::MOP modules as |
146 | # well. |
147 | |
148 | Class::MOP::Module->meta->add_attribute( |
149 | Class::MOP::Attribute->new('$:authority' => ( |
150 | reader => { |
151 | 'authority' => sub { |
152 | my $self = shift; |
153 | ${$self->get_package_symbol('$AUTHORITY')}; |
154 | } |
155 | }, |
156 | # NOTE: |
157 | # protect this from silliness |
158 | init_arg => '!............( DO NOT DO THIS )............!', |
c4260b45 |
159 | default => sub { \undef } |
f0480c45 |
160 | )) |
161 | ); |
162 | |
163 | ## -------------------------------------------------------- |
6d5355c3 |
164 | ## Class::MOP::Class |
165 | |
727919c5 |
166 | Class::MOP::Class->meta->add_attribute( |
351bd7d4 |
167 | Class::MOP::Attribute->new('%:attributes' => ( |
f7259199 |
168 | reader => { |
169 | # NOTE: we need to do this in order |
170 | # for the instance meta-object to |
171 | # not fall into meta-circular death |
172 | 'get_attribute_map' => sub { (shift)->{'%:attributes'} } |
173 | }, |
351bd7d4 |
174 | init_arg => ':attributes', |
727919c5 |
175 | default => sub { {} } |
176 | )) |
177 | ); |
178 | |
351bd7d4 |
179 | Class::MOP::Class->meta->add_attribute( |
c4260b45 |
180 | Class::MOP::Attribute->new('%:methods' => ( |
92330ee2 |
181 | reader => { |
182 | 'get_method_map' => sub { |
183 | my $self = shift; |
184 | my $map = $self->{'%:methods'}; |
92330ee2 |
185 | foreach my $symbol ($self->list_all_package_symbols('CODE')) { |
186 | my $code = $self->get_package_symbol('&' . $symbol); |
91e0eb4a |
187 | next if exists $map->{$symbol} && $map->{$symbol}->body == $code; |
92330ee2 |
188 | $map->{$symbol} = $self->method_metaclass->wrap($code); |
189 | } |
91e0eb4a |
190 | return $map; |
92330ee2 |
191 | } |
192 | }, |
7855ddba |
193 | default => sub { {} } |
c4260b45 |
194 | )) |
195 | ); |
196 | |
197 | Class::MOP::Class->meta->add_attribute( |
351bd7d4 |
198 | Class::MOP::Attribute->new('$:attribute_metaclass' => ( |
7b31baf4 |
199 | reader => 'attribute_metaclass', |
351bd7d4 |
200 | init_arg => ':attribute_metaclass', |
201 | default => 'Class::MOP::Attribute', |
202 | )) |
203 | ); |
204 | |
205 | Class::MOP::Class->meta->add_attribute( |
206 | Class::MOP::Attribute->new('$:method_metaclass' => ( |
7b31baf4 |
207 | reader => 'method_metaclass', |
351bd7d4 |
208 | init_arg => ':method_metaclass', |
209 | default => 'Class::MOP::Method', |
210 | )) |
211 | ); |
212 | |
2bab2be6 |
213 | Class::MOP::Class->meta->add_attribute( |
214 | Class::MOP::Attribute->new('$:instance_metaclass' => ( |
b880e0de |
215 | reader => { |
216 | # NOTE: we need to do this in order |
217 | # for the instance meta-object to |
218 | # not fall into meta-circular death |
219 | 'instance_metaclass' => sub { (shift)->{'$:instance_metaclass'} } |
220 | }, |
2bab2be6 |
221 | init_arg => ':instance_metaclass', |
222 | default => 'Class::MOP::Instance', |
223 | )) |
224 | ); |
225 | |
9d6dce77 |
226 | # NOTE: |
227 | # we don't actually need to tie the knot with |
228 | # Class::MOP::Class here, it is actually handled |
229 | # within Class::MOP::Class itself in the |
230 | # construct_class_instance method. |
231 | |
f0480c45 |
232 | ## -------------------------------------------------------- |
727919c5 |
233 | ## Class::MOP::Attribute |
234 | |
7b31baf4 |
235 | Class::MOP::Attribute->meta->add_attribute( |
236 | Class::MOP::Attribute->new('name' => ( |
b880e0de |
237 | reader => { |
238 | # NOTE: we need to do this in order |
239 | # for the instance meta-object to |
240 | # not fall into meta-circular death |
241 | 'name' => sub { (shift)->{name} } |
242 | } |
7b31baf4 |
243 | )) |
244 | ); |
245 | |
246 | Class::MOP::Attribute->meta->add_attribute( |
247 | Class::MOP::Attribute->new('associated_class' => ( |
b880e0de |
248 | reader => { |
249 | # NOTE: we need to do this in order |
250 | # for the instance meta-object to |
251 | # not fall into meta-circular death |
252 | 'associated_class' => sub { (shift)->{associated_class} } |
253 | } |
7b31baf4 |
254 | )) |
255 | ); |
256 | |
257 | Class::MOP::Attribute->meta->add_attribute( |
258 | Class::MOP::Attribute->new('accessor' => ( |
259 | reader => 'accessor', |
260 | predicate => 'has_accessor', |
261 | )) |
262 | ); |
263 | |
264 | Class::MOP::Attribute->meta->add_attribute( |
265 | Class::MOP::Attribute->new('reader' => ( |
266 | reader => 'reader', |
267 | predicate => 'has_reader', |
268 | )) |
269 | ); |
270 | |
271 | Class::MOP::Attribute->meta->add_attribute( |
272 | Class::MOP::Attribute->new('writer' => ( |
273 | reader => 'writer', |
274 | predicate => 'has_writer', |
275 | )) |
276 | ); |
277 | |
278 | Class::MOP::Attribute->meta->add_attribute( |
279 | Class::MOP::Attribute->new('predicate' => ( |
280 | reader => 'predicate', |
281 | predicate => 'has_predicate', |
282 | )) |
283 | ); |
284 | |
285 | Class::MOP::Attribute->meta->add_attribute( |
7d28758b |
286 | Class::MOP::Attribute->new('clearer' => ( |
287 | reader => 'clearer', |
288 | predicate => 'has_clearer', |
289 | )) |
290 | ); |
291 | |
292 | Class::MOP::Attribute->meta->add_attribute( |
7b31baf4 |
293 | Class::MOP::Attribute->new('init_arg' => ( |
294 | reader => 'init_arg', |
295 | predicate => 'has_init_arg', |
296 | )) |
297 | ); |
298 | |
299 | Class::MOP::Attribute->meta->add_attribute( |
300 | Class::MOP::Attribute->new('default' => ( |
301 | # default has a custom 'reader' method ... |
302 | predicate => 'has_default', |
303 | )) |
304 | ); |
305 | |
727919c5 |
306 | |
307 | # NOTE: (meta-circularity) |
308 | # This should be one of the last things done |
309 | # it will "tie the knot" with Class::MOP::Attribute |
310 | # so that it uses the attributes meta-objects |
311 | # to construct itself. |
312 | Class::MOP::Attribute->meta->add_method('new' => sub { |
313 | my $class = shift; |
314 | my $name = shift; |
315 | my %options = @_; |
316 | |
317 | (defined $name && $name) |
318 | || confess "You must provide a name for the attribute"; |
5659d76e |
319 | $options{init_arg} = $name |
320 | if not exists $options{init_arg}; |
148b4697 |
321 | |
322 | (Class::MOP::Attribute::is_default_a_coderef(\%options)) |
323 | || confess("References are not allowed as default values, you must ". |
324 | "wrap then in a CODE reference (ex: sub { [] } and not [])") |
325 | if exists $options{default} && ref $options{default}; |
651955fb |
326 | |
5659d76e |
327 | # return the new object |
328 | $class->meta->new_object(name => $name, %options); |
329 | }); |
330 | |
331 | Class::MOP::Attribute->meta->add_method('clone' => sub { |
a740253a |
332 | my $self = shift; |
a27ae83f |
333 | $self->meta->clone_object($self, @_); |
727919c5 |
334 | }); |
335 | |
f0480c45 |
336 | ## -------------------------------------------------------- |
337 | ## Now close all the Class::MOP::* classes |
4d47b77f |
338 | |
339 | Class::MOP::Package ->meta->make_immutable(inline_constructor => 0); |
340 | Class::MOP::Module ->meta->make_immutable(inline_constructor => 0); |
341 | Class::MOP::Class ->meta->make_immutable(inline_constructor => 0); |
342 | Class::MOP::Attribute->meta->make_immutable(inline_constructor => 0); |
343 | Class::MOP::Method ->meta->make_immutable(inline_constructor => 0); |
344 | Class::MOP::Instance ->meta->make_immutable(inline_constructor => 0); |
6e57504d |
345 | Class::MOP::Object ->meta->make_immutable(inline_constructor => 0); |
4d47b77f |
346 | |
94b19069 |
347 | 1; |
348 | |
349 | __END__ |
350 | |
351 | =pod |
352 | |
353 | =head1 NAME |
354 | |
355 | Class::MOP - A Meta Object Protocol for Perl 5 |
356 | |
357 | =head1 SYNOPSIS |
358 | |
a2e85e6c |
359 | # ... This will come later, for now see |
360 | # the other SYNOPSIS for more information |
94b19069 |
361 | |
362 | =head1 DESCRIPTON |
363 | |
364 | This module is an attempt to create a meta object protocol for the |
365 | Perl 5 object system. It makes no attempt to change the behavior or |
366 | characteristics of the Perl 5 object system, only to create a |
27e31eaf |
367 | protocol for its manipulation and introspection. |
94b19069 |
368 | |
369 | That said, it does attempt to create the tools for building a rich |
370 | set of extensions to the Perl 5 object system. Every attempt has been |
371 | made for these tools to keep to the spirit of the Perl 5 object |
372 | system that we all know and love. |
373 | |
40483095 |
374 | This documentation is admittedly sparse on details, as time permits |
375 | I will try to improve them. For now, I suggest looking at the items |
376 | listed in the L<SEE ALSO> section for more information. In particular |
377 | the book "The Art of the Meta Object Protocol" was very influential |
378 | in the development of this system. |
379 | |
bfe4d0fc |
380 | =head2 What is a Meta Object Protocol? |
381 | |
382 | A meta object protocol is an API to an object system. |
383 | |
384 | To be more specific, it is a set of abstractions of the components of |
385 | an object system (typically things like; classes, object, methods, |
386 | object attributes, etc.). These abstractions can then be used to both |
387 | inspect and manipulate the object system which they describe. |
388 | |
389 | It can be said that there are two MOPs for any object system; the |
390 | implicit MOP, and the explicit MOP. The implicit MOP handles things |
391 | like method dispatch or inheritance, which happen automatically as |
392 | part of how the object system works. The explicit MOP typically |
393 | handles the introspection/reflection features of the object system. |
394 | All object systems have implicit MOPs, without one, they would not |
395 | work. Explict MOPs however as less common, and depending on the |
396 | language can vary from restrictive (Reflection in Java or C#) to |
397 | wide open (CLOS is a perfect example). |
398 | |
e16da3e6 |
399 | =head2 Yet Another Class Builder!! Why? |
400 | |
401 | This is B<not> a class builder so much as it is a I<class builder |
402 | B<builder>>. My intent is that an end user does not use this module |
403 | directly, but instead this module is used by module authors to |
404 | build extensions and features onto the Perl 5 object system. |
405 | |
94b19069 |
406 | =head2 Who is this module for? |
407 | |
408 | This module is specifically for anyone who has ever created or |
409 | wanted to create a module for the Class:: namespace. The tools which |
410 | this module will provide will hopefully make it easier to do more |
411 | complex things with Perl 5 classes by removing such barriers as |
412 | the need to hack the symbol tables, or understand the fine details |
413 | of method dispatch. |
414 | |
bfe4d0fc |
415 | =head2 What changes do I have to make to use this module? |
416 | |
2eb717d5 |
417 | This module was designed to be as unintrusive as possible. Many of |
343203ee |
418 | its features are accessible without B<any> change to your existsing |
bfe4d0fc |
419 | code at all. It is meant to be a compliment to your existing code and |
2eb717d5 |
420 | not an intrusion on your code base. Unlike many other B<Class::> |
a2e85e6c |
421 | modules, this module B<does not> require you subclass it, or even that |
422 | you C<use> it in within your module's package. |
bfe4d0fc |
423 | |
2eb717d5 |
424 | The only features which requires additions to your code are the |
425 | attribute handling and instance construction features, and these are |
a2e85e6c |
426 | both completely optional features. The only reason for this is because |
2eb717d5 |
427 | Perl 5's object system does not actually have these features built |
428 | in. More information about this feature can be found below. |
bfe4d0fc |
429 | |
430 | =head2 A Note about Performance? |
431 | |
432 | It is a common misconception that explict MOPs are performance drains. |
433 | But this is not a universal truth at all, it is an side-effect of |
434 | specific implementations. For instance, using Java reflection is much |
435 | slower because the JVM cannot take advantage of any compiler |
436 | optimizations, and the JVM has to deal with much more runtime type |
437 | information as well. Reflection in C# is marginally better as it was |
438 | designed into the language and runtime (the CLR). In contrast, CLOS |
439 | (the Common Lisp Object System) was built to support an explicit MOP, |
440 | and so performance is tuned for it. |
441 | |
442 | This library in particular does it's absolute best to avoid putting |
2eb717d5 |
443 | B<any> drain at all upon your code's performance. In fact, by itself |
444 | it does nothing to affect your existing code. So you only pay for |
445 | what you actually use. |
bfe4d0fc |
446 | |
550d56db |
447 | =head2 About Metaclass compatibility |
448 | |
449 | This module makes sure that all metaclasses created are both upwards |
450 | and downwards compatible. The topic of metaclass compatibility is |
451 | highly esoteric and is something only encountered when doing deep and |
452 | involved metaclass hacking. There are two basic kinds of metaclass |
453 | incompatibility; upwards and downwards. |
454 | |
455 | Upwards metaclass compatibility means that the metaclass of a |
456 | given class is either the same as (or a subclass of) all of the |
457 | class's ancestors. |
458 | |
459 | Downward metaclass compatibility means that the metaclasses of a |
460 | given class's anscestors are all either the same as (or a subclass |
461 | of) that metaclass. |
462 | |
463 | Here is a diagram showing a set of two classes (C<A> and C<B>) and |
464 | two metaclasses (C<Meta::A> and C<Meta::B>) which have correct |
465 | metaclass compatibility both upwards and downwards. |
466 | |
467 | +---------+ +---------+ |
468 | | Meta::A |<----| Meta::B | <....... (instance of ) |
469 | +---------+ +---------+ <------- (inherits from) |
470 | ^ ^ |
471 | : : |
472 | +---------+ +---------+ |
473 | | A |<----| B | |
474 | +---------+ +---------+ |
475 | |
476 | As I said this is a highly esoteric topic and one you will only run |
477 | into if you do a lot of subclassing of B<Class::MOP::Class>. If you |
478 | are interested in why this is an issue see the paper |
479 | I<Uniform and safe metaclass composition> linked to in the |
480 | L<SEE ALSO> section of this document. |
481 | |
aa448b16 |
482 | =head2 Using custom metaclasses |
483 | |
484 | Always use the metaclass pragma when using a custom metaclass, this |
485 | will ensure the proper initialization order and not accidentely |
486 | create an incorrect type of metaclass for you. This is a very rare |
487 | problem, and one which can only occur if you are doing deep metaclass |
488 | programming. So in other words, don't worry about it. |
489 | |
94b19069 |
490 | =head1 PROTOCOLS |
491 | |
492 | The protocol is divided into 3 main sub-protocols: |
493 | |
494 | =over 4 |
495 | |
496 | =item The Class protocol |
497 | |
498 | This provides a means of manipulating and introspecting a Perl 5 |
499 | class. It handles all of symbol table hacking for you, and provides |
500 | a rich set of methods that go beyond simple package introspection. |
501 | |
552e3d24 |
502 | See L<Class::MOP::Class> for more details. |
503 | |
94b19069 |
504 | =item The Attribute protocol |
505 | |
506 | This provides a consistent represenation for an attribute of a |
507 | Perl 5 class. Since there are so many ways to create and handle |
508 | atttributes in Perl 5 OO, this attempts to provide as much of a |
509 | unified approach as possible, while giving the freedom and |
510 | flexibility to subclass for specialization. |
511 | |
552e3d24 |
512 | See L<Class::MOP::Attribute> for more details. |
513 | |
94b19069 |
514 | =item The Method protocol |
515 | |
516 | This provides a means of manipulating and introspecting methods in |
517 | the Perl 5 object system. As with attributes, there are many ways to |
518 | approach this topic, so we try to keep it pretty basic, while still |
519 | making it possible to extend the system in many ways. |
520 | |
552e3d24 |
521 | See L<Class::MOP::Method> for more details. |
94b19069 |
522 | |
523 | =back |
524 | |
be7677c7 |
525 | =head1 FUNCTIONS |
526 | |
527 | Class::MOP holds a cache of metaclasses, the following are functions |
528 | (B<not methods>) which can be used to access that cache. It is not |
529 | recommended that you mess with this, bad things could happen. But if |
530 | you are brave and willing to risk it, go for it. |
531 | |
532 | =over 4 |
533 | |
534 | =item B<get_all_metaclasses> |
535 | |
b9d9fc0b |
536 | This will return an hash of all the metaclass instances that have |
537 | been cached by B<Class::MOP::Class> keyed by the package name. |
538 | |
be7677c7 |
539 | =item B<get_all_metaclass_instances> |
540 | |
b9d9fc0b |
541 | This will return an array of all the metaclass instances that have |
542 | been cached by B<Class::MOP::Class>. |
543 | |
be7677c7 |
544 | =item B<get_all_metaclass_names> |
545 | |
b9d9fc0b |
546 | This will return an array of all the metaclass names that have |
547 | been cached by B<Class::MOP::Class>. |
548 | |
be7677c7 |
549 | =item B<get_metaclass_by_name ($name)> |
550 | |
551 | =item B<store_metaclass_by_name ($name, $meta)> |
552 | |
553 | =item B<weaken_metaclass ($name)> |
554 | |
555 | =item B<does_metaclass_exist ($name)> |
556 | |
557 | =item B<remove_metaclass_by_name ($name)> |
558 | |
559 | =back |
560 | |
552e3d24 |
561 | =head1 SEE ALSO |
8b978dd5 |
562 | |
552e3d24 |
563 | =head2 Books |
8b978dd5 |
564 | |
a2e85e6c |
565 | There are very few books out on Meta Object Protocols and Metaclasses |
566 | because it is such an esoteric topic. The following books are really |
567 | the only ones I have found. If you know of any more, B<I<please>> |
568 | email me and let me know, I would love to hear about them. |
569 | |
8b978dd5 |
570 | =over 4 |
571 | |
552e3d24 |
572 | =item "The Art of the Meta Object Protocol" |
8b978dd5 |
573 | |
552e3d24 |
574 | =item "Advances in Object-Oriented Metalevel Architecture and Reflection" |
8b978dd5 |
575 | |
b51af7f9 |
576 | =item "Putting MetaClasses to Work" |
577 | |
a2e85e6c |
578 | =item "Smalltalk: The Language" |
579 | |
94b19069 |
580 | =back |
581 | |
550d56db |
582 | =head2 Papers |
583 | |
584 | =over 4 |
585 | |
586 | =item Uniform and safe metaclass composition |
587 | |
588 | An excellent paper by the people who brought us the original Traits paper. |
589 | This paper is on how Traits can be used to do safe metaclass composition, |
590 | and offers an excellent introduction section which delves into the topic of |
591 | metaclass compatibility. |
592 | |
593 | L<http://www.iam.unibe.ch/~scg/Archive/Papers/Duca05ySafeMetaclassTrait.pdf> |
594 | |
595 | =item Safe Metaclass Programming |
596 | |
597 | This paper seems to precede the above paper, and propose a mix-in based |
598 | approach as opposed to the Traits based approach. Both papers have similar |
599 | information on the metaclass compatibility problem space. |
600 | |
601 | L<http://citeseer.ist.psu.edu/37617.html> |
602 | |
603 | =back |
604 | |
552e3d24 |
605 | =head2 Prior Art |
8b978dd5 |
606 | |
607 | =over 4 |
608 | |
7184ca14 |
609 | =item The Perl 6 MetaModel work in the Pugs project |
8b978dd5 |
610 | |
611 | =over 4 |
612 | |
552e3d24 |
613 | =item L<http://svn.openfoundry.org/pugs/perl5/Perl6-MetaModel> |
8b978dd5 |
614 | |
552e3d24 |
615 | =item L<http://svn.openfoundry.org/pugs/perl5/Perl6-ObjectSpace> |
8b978dd5 |
616 | |
617 | =back |
618 | |
94b19069 |
619 | =back |
620 | |
a2e85e6c |
621 | =head1 SIMILAR MODULES |
622 | |
623 | As I have said above, this module is a class-builder-builder, so it is |
624 | not the same thing as modules like L<Class::Accessor> and |
625 | L<Class::MethodMaker>. That being said there are very few modules on CPAN |
626 | with similar goals to this module. The one I have found which is most |
550d56db |
627 | like this module is L<Class::Meta>, although it's philosophy and the MOP it |
628 | creates are very different from this modules. |
94b19069 |
629 | |
a2e85e6c |
630 | =head1 BUGS |
631 | |
632 | All complex software has bugs lurking in it, and this module is no |
633 | exception. If you find a bug please either email me, or add the bug |
634 | to cpan-RT. |
635 | |
22286063 |
636 | =head1 CODE COVERAGE |
637 | |
638 | I use L<Devel::Cover> to test the code coverage of my tests, below is the |
639 | L<Devel::Cover> report on this module's test suite. |
640 | |
641 | ---------------------------- ------ ------ ------ ------ ------ ------ ------ |
642 | File stmt bran cond sub pod time total |
643 | ---------------------------- ------ ------ ------ ------ ------ ------ ------ |
b9d9fc0b |
644 | Class/MOP.pm 78.0 87.5 55.6 71.4 100.0 12.4 76.8 |
645 | Class/MOP/Attribute.pm 83.4 75.6 86.7 94.4 100.0 8.9 85.2 |
646 | Class/MOP/Class.pm 96.9 75.8 43.2 98.0 100.0 55.3 83.6 |
647 | Class/MOP/Class/Immutable.pm 88.5 53.8 n/a 95.8 100.0 1.1 84.7 |
648 | Class/MOP/Instance.pm 87.9 75.0 33.3 89.7 100.0 10.1 89.1 |
649 | Class/MOP/Method.pm 97.6 60.0 57.9 76.9 100.0 1.5 82.8 |
650 | Class/MOP/Module.pm 87.5 n/a 11.1 83.3 100.0 0.3 66.7 |
651 | Class/MOP/Object.pm 100.0 n/a 33.3 100.0 100.0 0.1 89.5 |
652 | Class/MOP/Package.pm 95.1 69.0 33.3 100.0 100.0 9.9 85.5 |
653 | metaclass.pm 100.0 100.0 83.3 100.0 n/a 0.5 97.7 |
22286063 |
654 | ---------------------------- ------ ------ ------ ------ ------ ------ ------ |
b9d9fc0b |
655 | Total 91.5 72.1 48.8 90.7 100.0 100.0 84.2 |
22286063 |
656 | ---------------------------- ------ ------ ------ ------ ------ ------ ------ |
657 | |
a2e85e6c |
658 | =head1 ACKNOWLEDGEMENTS |
659 | |
660 | =over 4 |
661 | |
b9d9fc0b |
662 | =item Rob Kinyon |
a2e85e6c |
663 | |
664 | Thanks to Rob for actually getting the development of this module kick-started. |
665 | |
666 | =back |
667 | |
1a09d9cc |
668 | =head1 AUTHORS |
94b19069 |
669 | |
a2e85e6c |
670 | Stevan Little E<lt>stevan@iinteractive.comE<gt> |
552e3d24 |
671 | |
1a09d9cc |
672 | Yuval Kogman E<lt>nothingmuch@woobling.comE<gt> |
673 | |
94b19069 |
674 | =head1 COPYRIGHT AND LICENSE |
675 | |
676 | Copyright 2006 by Infinity Interactive, Inc. |
677 | |
678 | L<http://www.iinteractive.com> |
679 | |
680 | This library is free software; you can redistribute it and/or modify |
681 | it under the same terms as Perl itself. |
682 | |
683 | =cut |