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8b978dd5 |
1 | |
2 | package Class::MOP::Class; |
3 | |
4 | use strict; |
5 | use warnings; |
6 | |
7 | use Carp 'confess'; |
0882828e |
8 | use Scalar::Util 'blessed', 'reftype'; |
8b978dd5 |
9 | use Sub::Name 'subname'; |
10 | use B 'svref_2object'; |
11 | |
12 | our $VERSION = '0.01'; |
13 | |
14 | # Creation |
15 | |
bfe4d0fc |
16 | { |
17 | # Metaclasses are singletons, so we cache them here. |
18 | # there is no need to worry about destruction though |
19 | # because they should die only when the program dies. |
20 | # After all, do package definitions even get reaped? |
21 | my %METAS; |
22 | sub initialize { |
23 | my ($class, $package_name) = @_; |
24 | (defined $package_name && $package_name) |
25 | || confess "You must pass a package name"; |
e16da3e6 |
26 | $METAS{$package_name} ||= bless { |
27 | '$:pkg' => $package_name, |
28 | '%:attrs' => {} |
29 | } => blessed($class) || $class; |
bfe4d0fc |
30 | } |
8b978dd5 |
31 | } |
32 | |
33 | sub create { |
34 | my ($class, $package_name, $package_version, %options) = @_; |
bfe4d0fc |
35 | (defined $package_name && $package_name) |
8b978dd5 |
36 | || confess "You must pass a package name"; |
37 | my $code = "package $package_name;"; |
38 | $code .= "\$$package_name\:\:VERSION = '$package_version';" |
39 | if defined $package_version; |
40 | eval $code; |
41 | confess "creation of $package_name failed : $@" if $@; |
bfe4d0fc |
42 | my $meta = $class->initialize($package_name); |
8b978dd5 |
43 | $meta->superclasses(@{$options{superclasses}}) |
44 | if exists $options{superclasses}; |
bfe4d0fc |
45 | if (exists $options{methods}) { |
46 | foreach my $method_name (keys %{$options{methods}}) { |
47 | $meta->add_method($method_name, $options{methods}->{$method_name}); |
48 | } |
49 | } |
8b978dd5 |
50 | return $meta; |
51 | } |
52 | |
e16da3e6 |
53 | # Instance Construction |
54 | |
55 | sub construct_instance { |
56 | my ($canidate, %params) = @_; |
57 | # ... |
58 | } |
59 | |
8b978dd5 |
60 | # Informational |
61 | |
e16da3e6 |
62 | sub name { $_[0]->{'$:pkg'} } |
8b978dd5 |
63 | |
64 | sub version { |
65 | my $self = shift; |
66 | no strict 'refs'; |
67 | ${$self->name . '::VERSION'}; |
68 | } |
69 | |
70 | # Inheritance |
71 | |
72 | sub superclasses { |
73 | my $self = shift; |
74 | no strict 'refs'; |
75 | if (@_) { |
76 | my @supers = @_; |
77 | @{$self->name . '::ISA'} = @supers; |
78 | } |
79 | @{$self->name . '::ISA'}; |
80 | } |
81 | |
82 | sub class_precedence_list { |
83 | my $self = shift; |
bfe4d0fc |
84 | # NOTE: |
85 | # We need to check for ciruclar inheirtance here. |
86 | # This will do nothing if all is well, and blow |
87 | # up otherwise. Yes, it's an ugly hack, better |
88 | # suggestions are welcome. |
89 | { $self->name->isa('This is a test for circular inheritance') } |
90 | # ... and no back to our regularly scheduled program |
8b978dd5 |
91 | ( |
92 | $self->name, |
93 | map { |
bfe4d0fc |
94 | $self->initialize($_)->class_precedence_list() |
8b978dd5 |
95 | } $self->superclasses() |
96 | ); |
97 | } |
98 | |
0882828e |
99 | ## Methods |
100 | |
101 | sub add_method { |
102 | my ($self, $method_name, $method) = @_; |
103 | (defined $method_name && $method_name) |
104 | || confess "You must define a method name"; |
a5eca695 |
105 | # use reftype here to allow for blessed subs ... |
0882828e |
106 | (reftype($method) && reftype($method) eq 'CODE') |
107 | || confess "Your code block must be a CODE reference"; |
108 | my $full_method_name = ($self->name . '::' . $method_name); |
109 | |
110 | no strict 'refs'; |
c9b8b7f9 |
111 | no warnings 'redefine'; |
0882828e |
112 | *{$full_method_name} = subname $full_method_name => $method; |
113 | } |
114 | |
bfe4d0fc |
115 | { |
116 | |
117 | ## private utility functions for has_method |
118 | my $_find_subroutine_package_name = sub { eval { svref_2object($_[0])->GV->STASH->NAME } }; |
119 | my $_find_subroutine_name = sub { eval { svref_2object($_[0])->GV->NAME } }; |
120 | |
121 | sub has_method { |
c9b8b7f9 |
122 | my ($self, $method_name) = @_; |
bfe4d0fc |
123 | (defined $method_name && $method_name) |
124 | || confess "You must define a method name"; |
0882828e |
125 | |
bfe4d0fc |
126 | my $sub_name = ($self->name . '::' . $method_name); |
0882828e |
127 | |
bfe4d0fc |
128 | no strict 'refs'; |
129 | return 0 if !defined(&{$sub_name}); |
130 | return 0 if $_find_subroutine_package_name->(\&{$sub_name}) ne $self->name && |
131 | $_find_subroutine_name->(\&{$sub_name}) ne '__ANON__'; |
132 | return 1; |
133 | } |
134 | |
0882828e |
135 | } |
136 | |
137 | sub get_method { |
c9b8b7f9 |
138 | my ($self, $method_name) = @_; |
0882828e |
139 | (defined $method_name && $method_name) |
140 | || confess "You must define a method name"; |
141 | |
142 | no strict 'refs'; |
143 | return \&{$self->name . '::' . $method_name} |
bfe4d0fc |
144 | if $self->has_method($method_name); |
c9b8b7f9 |
145 | return; # <- make sure to return undef |
146 | } |
147 | |
148 | sub remove_method { |
149 | my ($self, $method_name) = @_; |
150 | (defined $method_name && $method_name) |
151 | || confess "You must define a method name"; |
152 | |
153 | my $removed_method = $self->get_method($method_name); |
154 | |
155 | no strict 'refs'; |
156 | delete ${$self->name . '::'}{$method_name} |
157 | if defined $removed_method; |
158 | |
159 | return $removed_method; |
160 | } |
161 | |
162 | sub get_method_list { |
163 | my $self = shift; |
164 | no strict 'refs'; |
a5eca695 |
165 | grep { $self->has_method($_) } %{$self->name . '::'}; |
166 | } |
167 | |
168 | sub compute_all_applicable_methods { |
169 | my $self = shift; |
170 | my @methods; |
171 | # keep a record of what we have seen |
172 | # here, this will handle all the |
173 | # inheritence issues because we are |
174 | # using the &class_precedence_list |
175 | my (%seen_class, %seen_method); |
176 | foreach my $class ($self->class_precedence_list()) { |
177 | next if $seen_class{$class}; |
178 | $seen_class{$class}++; |
179 | # fetch the meta-class ... |
180 | my $meta = $self->initialize($class); |
181 | foreach my $method_name ($meta->get_method_list()) { |
182 | next if exists $seen_method{$method_name}; |
183 | $seen_method{$method_name}++; |
184 | push @methods => { |
185 | name => $method_name, |
186 | class => $class, |
187 | code => $meta->get_method($method_name) |
188 | }; |
189 | } |
190 | } |
191 | return @methods; |
192 | } |
193 | |
a5eca695 |
194 | sub find_all_methods_by_name { |
195 | my ($self, $method_name) = @_; |
196 | (defined $method_name && $method_name) |
197 | || confess "You must define a method name to find"; |
198 | my @methods; |
199 | # keep a record of what we have seen |
200 | # here, this will handle all the |
201 | # inheritence issues because we are |
202 | # using the &class_precedence_list |
203 | my %seen_class; |
204 | foreach my $class ($self->class_precedence_list()) { |
205 | next if $seen_class{$class}; |
206 | $seen_class{$class}++; |
207 | # fetch the meta-class ... |
208 | my $meta = $self->initialize($class); |
209 | push @methods => { |
210 | name => $method_name, |
211 | class => $class, |
212 | code => $meta->get_method($method_name) |
213 | } if $meta->has_method($method_name); |
214 | } |
215 | return @methods; |
216 | |
8b978dd5 |
217 | } |
218 | |
552e3d24 |
219 | ## Attributes |
220 | |
e16da3e6 |
221 | sub add_attribute { |
222 | my ($self, $attribute_name, $attribute) = @_; |
223 | (defined $attribute_name && $attribute_name) |
224 | || confess "You must define an attribute name"; |
225 | (blessed($attribute) && $attribute->isa('Class::MOP::Attribute')) |
226 | || confess "Your attribute must be an instance of Class::MOP::Attribute (or a subclass)"; |
227 | $self->{'%:attrs'}->{$attribute_name} = $attribute; |
228 | } |
229 | |
230 | sub has_attribute { |
231 | my ($self, $attribute_name) = @_; |
232 | (defined $attribute_name && $attribute_name) |
233 | || confess "You must define an attribute name"; |
234 | exists $self->{'%:attrs'}->{$attribute_name} ? 1 : 0; |
235 | } |
236 | |
237 | sub get_attribute { |
238 | my ($self, $attribute_name) = @_; |
239 | (defined $attribute_name && $attribute_name) |
240 | || confess "You must define an attribute name"; |
241 | return $self->{'%:attrs'}->{$attribute_name} |
242 | if $self->has_attribute($attribute_name); |
243 | } |
244 | |
245 | sub remove_attribute { |
246 | my ($self, $attribute_name) = @_; |
247 | (defined $attribute_name && $attribute_name) |
248 | || confess "You must define an attribute name"; |
249 | my $removed_attribute = $self->{'%:attrs'}->{$attribute_name}; |
250 | delete $self->{'%:attrs'}->{$attribute_name} |
251 | if defined $removed_attribute; |
252 | return $removed_attribute; |
253 | } |
254 | |
255 | sub get_attribute_list { |
256 | my $self = shift; |
257 | keys %{$self->{'%:attrs'}}; |
258 | } |
259 | |
260 | sub compute_all_applicable_attributes { |
261 | my $self = shift; |
262 | my @attrs; |
263 | # keep a record of what we have seen |
264 | # here, this will handle all the |
265 | # inheritence issues because we are |
266 | # using the &class_precedence_list |
267 | my (%seen_class, %seen_attr); |
268 | foreach my $class ($self->class_precedence_list()) { |
269 | next if $seen_class{$class}; |
270 | $seen_class{$class}++; |
271 | # fetch the meta-class ... |
272 | my $meta = $self->initialize($class); |
273 | foreach my $attr_name ($meta->get_attribute_list()) { |
274 | next if exists $seen_attr{$attr_name}; |
275 | $seen_attr{$attr_name}++; |
276 | push @attrs => { |
277 | name => $attr_name, |
278 | class => $class, |
279 | attribute => $meta->get_attribute($attr_name) |
280 | }; |
281 | } |
282 | } |
283 | return @attrs; |
284 | } |
285 | |
286 | sub create_all_accessors { |
287 | |
288 | } |
552e3d24 |
289 | |
8b978dd5 |
290 | 1; |
291 | |
292 | __END__ |
293 | |
294 | =pod |
295 | |
296 | =head1 NAME |
297 | |
298 | Class::MOP::Class - Class Meta Object |
299 | |
300 | =head1 SYNOPSIS |
301 | |
302 | =head1 DESCRIPTION |
303 | |
552e3d24 |
304 | =head1 METHODS |
305 | |
306 | =head2 Class construction |
307 | |
308 | These methods handle creating Class objects, which can be used to |
309 | both create new classes, and analyze pre-existing ones. |
310 | |
311 | This module will internally store references to all the instances |
312 | you create with these methods, so that they do not need to be |
313 | created any more than nessecary. Basically, they are singletons. |
314 | |
315 | =over 4 |
316 | |
317 | =item B<create ($package_name, ?$package_version, |
318 | superclasses => ?@superclasses, |
319 | methods => ?%methods, |
320 | attributes => ?%attributes)> |
321 | |
322 | This returns the basic Class object, bringing the specified |
323 | C<$package_name> into existence and adding any of the |
324 | C<$package_version>, C<@superclasses>, C<%methods> and C<%attributes> |
325 | to it. |
326 | |
327 | =item B<initialize ($package_name)> |
328 | |
329 | This initializes a Class object for a given a C<$package_name>. |
330 | |
331 | =back |
332 | |
333 | =head2 Instance construction |
334 | |
335 | =over 4 |
336 | |
337 | =item B<construct_instance ($canidate, %params)> |
338 | |
339 | This will construct and instance using the C<$canidate> as storage |
340 | (currently only HASH references are supported). This will collect all |
341 | the applicable attribute meta-objects and layout out the fields in the |
342 | C<$canidate>, it will then initialize them using either use the |
343 | corresponding key in C<%params> or any default value or initializer |
344 | found in the attribute meta-object. |
345 | |
346 | =back |
347 | |
348 | =head2 Informational |
349 | |
350 | =over 4 |
351 | |
352 | =item B<name> |
353 | |
354 | This is a read-only attribute which returns the package name that |
355 | the Class is stored in. |
356 | |
357 | =item B<version> |
358 | |
359 | This is a read-only attribute which returns the C<$VERSION> of the |
360 | package the Class is stored in. |
361 | |
362 | =back |
363 | |
364 | =head2 Inheritance Relationships |
365 | |
366 | =over 4 |
367 | |
368 | =item B<superclasses (?@superclasses)> |
369 | |
370 | This is a read-write attribute which represents the superclass |
371 | relationships of this Class. Basically, it can get and set the |
372 | C<@ISA> for you. |
373 | |
374 | =item B<class_precedence_list> |
375 | |
376 | This computes the a list of the Class's ancestors in the same order |
377 | in which method dispatch will be done. |
378 | |
379 | =back |
380 | |
381 | =head2 Methods |
382 | |
383 | =over 4 |
384 | |
385 | =item B<add_method ($method_name, $method)> |
386 | |
387 | This will take a C<$method_name> and CODE reference to that |
388 | C<$method> and install it into the Class. |
389 | |
390 | B<NOTE> : This does absolutely nothing special to C<$method> |
391 | other than use B<Sub::Name> to make sure it is tagged with the |
392 | correct name, and therefore show up correctly in stack traces and |
393 | such. |
394 | |
395 | =item B<has_method ($method_name)> |
396 | |
397 | This just provides a simple way to check if the Class implements |
398 | a specific C<$method_name>. It will I<not> however, attempt to check |
399 | if the class inherits the method. |
400 | |
401 | This will correctly handle functions defined outside of the package |
402 | that use a fully qualified name (C<sub Package::name { ... }>). |
403 | |
404 | This will correctly handle functions renamed with B<Sub::Name> and |
405 | installed using the symbol tables. However, if you are naming the |
406 | subroutine outside of the package scope, you must use the fully |
407 | qualified name, including the package name, for C<has_method> to |
408 | correctly identify it. |
409 | |
410 | This will attempt to correctly ignore functions imported from other |
411 | packages using B<Exporter>. It breaks down if the function imported |
412 | is an C<__ANON__> sub (such as with C<use constant>), which very well |
413 | may be a valid method being applied to the class. |
414 | |
415 | In short, this method cannot always be trusted to determine if the |
416 | C<$method_name> is actually a method. However, it will DWIM about |
417 | 90% of the time, so it's a small trade off IMO. |
418 | |
419 | =item B<get_method ($method_name)> |
420 | |
421 | This will return a CODE reference of the specified C<$method_name>, |
422 | or return undef if that method does not exist. |
423 | |
424 | =item B<remove_method ($method_name)> |
425 | |
426 | This will attempt to remove a given C<$method_name> from the Class. |
427 | It will return the CODE reference that it has removed, and will |
428 | attempt to use B<Sub::Name> to clear the methods associated name. |
429 | |
430 | =item B<get_method_list> |
431 | |
432 | This will return a list of method names for all I<locally> defined |
433 | methods. It does B<not> provide a list of all applicable methods, |
434 | including any inherited ones. If you want a list of all applicable |
435 | methods, use the C<compute_all_applicable_methods> method. |
436 | |
437 | =item B<compute_all_applicable_methods> |
438 | |
439 | This will return a list of all the methods names this Class will |
440 | support, taking into account inheritance. The list will be a list of |
441 | HASH references, each one containing the following information; method |
442 | name, the name of the class in which the method lives and a CODE |
443 | reference for the actual method. |
444 | |
445 | =item B<find_all_methods_by_name ($method_name)> |
446 | |
447 | This will traverse the inheritence hierarchy and locate all methods |
448 | with a given C<$method_name>. Similar to |
449 | C<compute_all_applicable_methods> it returns a list of HASH references |
450 | with the following information; method name (which will always be the |
451 | same as C<$method_name>), the name of the class in which the method |
452 | lives and a CODE reference for the actual method. |
453 | |
454 | The list of methods produced is a distinct list, meaning there are no |
455 | duplicates in it. This is especially useful for things like object |
456 | initialization and destruction where you only want the method called |
457 | once, and in the correct order. |
458 | |
459 | =back |
460 | |
461 | =head2 Attributes |
462 | |
463 | It should be noted that since there is no one consistent way to define |
464 | the attributes of a class in Perl 5. These methods can only work with |
465 | the information given, and can not easily discover information on |
466 | their own. |
467 | |
468 | =over 4 |
469 | |
470 | =item B<add_attribute ($attribute_name, $attribute_meta_object)> |
471 | |
472 | This stores a C<$attribute_meta_object> in the Class object and |
473 | associates it with the C<$attribute_name>. Unlike methods, attributes |
474 | within the MOP are stored as meta-information only. They will be used |
475 | later to construct instances from (see C<construct_instance> above). |
476 | More details about the attribute meta-objects can be found in the |
477 | L<The Attribute protocol> section of this document. |
478 | |
479 | =item B<has_attribute ($attribute_name)> |
480 | |
481 | Checks to see if this Class has an attribute by the name of |
482 | C<$attribute_name> and returns a boolean. |
483 | |
484 | =item B<get_attribute ($attribute_name)> |
485 | |
486 | Returns the attribute meta-object associated with C<$attribute_name>, |
487 | if none is found, it will return undef. |
488 | |
489 | =item B<remove_attribute ($attribute_name)> |
490 | |
491 | This will remove the attribute meta-object stored at |
492 | C<$attribute_name>, then return the removed attribute meta-object. |
493 | |
494 | B<NOTE:> Removing an attribute will only affect future instances of |
495 | the class, it will not make any attempt to remove the attribute from |
496 | any existing instances of the class. |
497 | |
498 | =item B<get_attribute_list> |
499 | |
500 | This returns a list of attribute names which are defined in the local |
501 | class. If you want a list of all applicable attributes for a class, |
502 | use the C<compute_all_applicable_attributes> method. |
503 | |
504 | =item B<compute_all_applicable_attributes> |
505 | |
506 | This will traverse the inheritance heirachy and return a list of HASH |
507 | references for all the applicable attributes for this class. The HASH |
508 | references will contain the following information; the attribute name, |
509 | the class which the attribute is associated with and the actual |
510 | attribute meta-object |
511 | |
512 | =item B<create_all_accessors> |
513 | |
514 | This will communicate with all of the classes attributes to create |
515 | and install the appropriate accessors. (see L<The Attribute Protocol> |
516 | below for more details). |
517 | |
518 | =back |
519 | |
8b978dd5 |
520 | =head1 AUTHOR |
521 | |
522 | Stevan Little E<gt>stevan@iinteractive.comE<lt> |
523 | |
524 | =head1 COPYRIGHT AND LICENSE |
525 | |
526 | Copyright 2006 by Infinity Interactive, Inc. |
527 | |
528 | L<http://www.iinteractive.com> |
529 | |
530 | This library is free software; you can redistribute it and/or modify |
531 | it under the same terms as Perl itself. |
532 | |
533 | =cut |