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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"; |
6ddf42a0 |
26 | $METAS{$package_name} ||= bless [ $package_name, {} ] => blessed($class) || $class; |
bfe4d0fc |
27 | } |
8b978dd5 |
28 | } |
29 | |
30 | sub create { |
31 | my ($class, $package_name, $package_version, %options) = @_; |
bfe4d0fc |
32 | (defined $package_name && $package_name) |
8b978dd5 |
33 | || confess "You must pass a package name"; |
34 | my $code = "package $package_name;"; |
35 | $code .= "\$$package_name\:\:VERSION = '$package_version';" |
36 | if defined $package_version; |
37 | eval $code; |
38 | confess "creation of $package_name failed : $@" if $@; |
bfe4d0fc |
39 | my $meta = $class->initialize($package_name); |
8b978dd5 |
40 | $meta->superclasses(@{$options{superclasses}}) |
41 | if exists $options{superclasses}; |
bfe4d0fc |
42 | if (exists $options{methods}) { |
43 | foreach my $method_name (keys %{$options{methods}}) { |
44 | $meta->add_method($method_name, $options{methods}->{$method_name}); |
45 | } |
46 | } |
8b978dd5 |
47 | return $meta; |
48 | } |
49 | |
50 | # Informational |
51 | |
6ddf42a0 |
52 | sub name { ${$_[0]}[0] } |
8b978dd5 |
53 | |
54 | sub version { |
55 | my $self = shift; |
56 | no strict 'refs'; |
57 | ${$self->name . '::VERSION'}; |
58 | } |
59 | |
60 | # Inheritance |
61 | |
62 | sub superclasses { |
63 | my $self = shift; |
64 | no strict 'refs'; |
65 | if (@_) { |
66 | my @supers = @_; |
67 | @{$self->name . '::ISA'} = @supers; |
68 | } |
69 | @{$self->name . '::ISA'}; |
70 | } |
71 | |
72 | sub class_precedence_list { |
73 | my $self = shift; |
bfe4d0fc |
74 | # NOTE: |
75 | # We need to check for ciruclar inheirtance here. |
76 | # This will do nothing if all is well, and blow |
77 | # up otherwise. Yes, it's an ugly hack, better |
78 | # suggestions are welcome. |
79 | { $self->name->isa('This is a test for circular inheritance') } |
80 | # ... and no back to our regularly scheduled program |
8b978dd5 |
81 | ( |
82 | $self->name, |
83 | map { |
bfe4d0fc |
84 | $self->initialize($_)->class_precedence_list() |
8b978dd5 |
85 | } $self->superclasses() |
86 | ); |
87 | } |
88 | |
0882828e |
89 | ## Methods |
90 | |
91 | sub add_method { |
92 | my ($self, $method_name, $method) = @_; |
93 | (defined $method_name && $method_name) |
94 | || confess "You must define a method name"; |
a5eca695 |
95 | # use reftype here to allow for blessed subs ... |
0882828e |
96 | (reftype($method) && reftype($method) eq 'CODE') |
97 | || confess "Your code block must be a CODE reference"; |
98 | my $full_method_name = ($self->name . '::' . $method_name); |
99 | |
100 | no strict 'refs'; |
c9b8b7f9 |
101 | no warnings 'redefine'; |
0882828e |
102 | *{$full_method_name} = subname $full_method_name => $method; |
103 | } |
104 | |
bfe4d0fc |
105 | { |
106 | |
107 | ## private utility functions for has_method |
108 | my $_find_subroutine_package_name = sub { eval { svref_2object($_[0])->GV->STASH->NAME } }; |
109 | my $_find_subroutine_name = sub { eval { svref_2object($_[0])->GV->NAME } }; |
110 | |
111 | sub has_method { |
c9b8b7f9 |
112 | my ($self, $method_name) = @_; |
bfe4d0fc |
113 | (defined $method_name && $method_name) |
114 | || confess "You must define a method name"; |
0882828e |
115 | |
bfe4d0fc |
116 | my $sub_name = ($self->name . '::' . $method_name); |
0882828e |
117 | |
bfe4d0fc |
118 | no strict 'refs'; |
119 | return 0 if !defined(&{$sub_name}); |
120 | return 0 if $_find_subroutine_package_name->(\&{$sub_name}) ne $self->name && |
121 | $_find_subroutine_name->(\&{$sub_name}) ne '__ANON__'; |
122 | return 1; |
123 | } |
124 | |
0882828e |
125 | } |
126 | |
127 | sub get_method { |
c9b8b7f9 |
128 | my ($self, $method_name) = @_; |
0882828e |
129 | (defined $method_name && $method_name) |
130 | || confess "You must define a method name"; |
131 | |
132 | no strict 'refs'; |
133 | return \&{$self->name . '::' . $method_name} |
bfe4d0fc |
134 | if $self->has_method($method_name); |
c9b8b7f9 |
135 | return; # <- make sure to return undef |
136 | } |
137 | |
138 | sub remove_method { |
139 | my ($self, $method_name) = @_; |
140 | (defined $method_name && $method_name) |
141 | || confess "You must define a method name"; |
142 | |
143 | my $removed_method = $self->get_method($method_name); |
144 | |
145 | no strict 'refs'; |
146 | delete ${$self->name . '::'}{$method_name} |
147 | if defined $removed_method; |
148 | |
149 | return $removed_method; |
150 | } |
151 | |
152 | sub get_method_list { |
153 | my $self = shift; |
154 | no strict 'refs'; |
a5eca695 |
155 | grep { $self->has_method($_) } %{$self->name . '::'}; |
156 | } |
157 | |
158 | sub compute_all_applicable_methods { |
159 | my $self = shift; |
160 | my @methods; |
161 | # keep a record of what we have seen |
162 | # here, this will handle all the |
163 | # inheritence issues because we are |
164 | # using the &class_precedence_list |
165 | my (%seen_class, %seen_method); |
166 | foreach my $class ($self->class_precedence_list()) { |
167 | next if $seen_class{$class}; |
168 | $seen_class{$class}++; |
169 | # fetch the meta-class ... |
170 | my $meta = $self->initialize($class); |
171 | foreach my $method_name ($meta->get_method_list()) { |
172 | next if exists $seen_method{$method_name}; |
173 | $seen_method{$method_name}++; |
174 | push @methods => { |
175 | name => $method_name, |
176 | class => $class, |
177 | code => $meta->get_method($method_name) |
178 | }; |
179 | } |
180 | } |
181 | return @methods; |
182 | } |
183 | |
184 | ## Recursive Version of compute_all_applicable_methods |
185 | # sub compute_all_applicable_methods { |
186 | # my ($self, $seen) = @_; |
187 | # $seen ||= {}; |
188 | # ( |
189 | # (map { |
190 | # if (exists $seen->{$_}) { |
191 | # (); |
192 | # } |
193 | # else { |
194 | # $seen->{$_}++; |
195 | # { |
196 | # name => $_, |
197 | # class => $self->name, |
198 | # code => $self->get_method($_) |
199 | # }; |
200 | # } |
201 | # } $self->get_method_list()), |
202 | # map { |
203 | # $self->initialize($_)->compute_all_applicable_methods($seen) |
204 | # } $self->superclasses() |
205 | # ); |
206 | # } |
207 | |
208 | sub find_all_methods_by_name { |
209 | my ($self, $method_name) = @_; |
210 | (defined $method_name && $method_name) |
211 | || confess "You must define a method name to find"; |
212 | my @methods; |
213 | # keep a record of what we have seen |
214 | # here, this will handle all the |
215 | # inheritence issues because we are |
216 | # using the &class_precedence_list |
217 | my %seen_class; |
218 | foreach my $class ($self->class_precedence_list()) { |
219 | next if $seen_class{$class}; |
220 | $seen_class{$class}++; |
221 | # fetch the meta-class ... |
222 | my $meta = $self->initialize($class); |
223 | push @methods => { |
224 | name => $method_name, |
225 | class => $class, |
226 | code => $meta->get_method($method_name) |
227 | } if $meta->has_method($method_name); |
228 | } |
229 | return @methods; |
230 | |
8b978dd5 |
231 | } |
232 | |
552e3d24 |
233 | ## Attributes |
234 | |
235 | sub has_attribute {} |
236 | sub get_attribute {} |
237 | sub add_attribute {} |
238 | sub remove_attribute {} |
239 | sub get_attribute_list {} |
240 | sub compute_all_applicable_attributes {} |
241 | sub create_all_accessors {} |
242 | |
8b978dd5 |
243 | 1; |
244 | |
245 | __END__ |
246 | |
247 | =pod |
248 | |
249 | =head1 NAME |
250 | |
251 | Class::MOP::Class - Class Meta Object |
252 | |
253 | =head1 SYNOPSIS |
254 | |
255 | =head1 DESCRIPTION |
256 | |
552e3d24 |
257 | =head1 METHODS |
258 | |
259 | =head2 Class construction |
260 | |
261 | These methods handle creating Class objects, which can be used to |
262 | both create new classes, and analyze pre-existing ones. |
263 | |
264 | This module will internally store references to all the instances |
265 | you create with these methods, so that they do not need to be |
266 | created any more than nessecary. Basically, they are singletons. |
267 | |
268 | =over 4 |
269 | |
270 | =item B<create ($package_name, ?$package_version, |
271 | superclasses => ?@superclasses, |
272 | methods => ?%methods, |
273 | attributes => ?%attributes)> |
274 | |
275 | This returns the basic Class object, bringing the specified |
276 | C<$package_name> into existence and adding any of the |
277 | C<$package_version>, C<@superclasses>, C<%methods> and C<%attributes> |
278 | to it. |
279 | |
280 | =item B<initialize ($package_name)> |
281 | |
282 | This initializes a Class object for a given a C<$package_name>. |
283 | |
284 | =back |
285 | |
286 | =head2 Instance construction |
287 | |
288 | =over 4 |
289 | |
290 | =item B<construct_instance ($canidate, %params)> |
291 | |
292 | This will construct and instance using the C<$canidate> as storage |
293 | (currently only HASH references are supported). This will collect all |
294 | the applicable attribute meta-objects and layout out the fields in the |
295 | C<$canidate>, it will then initialize them using either use the |
296 | corresponding key in C<%params> or any default value or initializer |
297 | found in the attribute meta-object. |
298 | |
299 | =back |
300 | |
301 | =head2 Informational |
302 | |
303 | =over 4 |
304 | |
305 | =item B<name> |
306 | |
307 | This is a read-only attribute which returns the package name that |
308 | the Class is stored in. |
309 | |
310 | =item B<version> |
311 | |
312 | This is a read-only attribute which returns the C<$VERSION> of the |
313 | package the Class is stored in. |
314 | |
315 | =back |
316 | |
317 | =head2 Inheritance Relationships |
318 | |
319 | =over 4 |
320 | |
321 | =item B<superclasses (?@superclasses)> |
322 | |
323 | This is a read-write attribute which represents the superclass |
324 | relationships of this Class. Basically, it can get and set the |
325 | C<@ISA> for you. |
326 | |
327 | =item B<class_precedence_list> |
328 | |
329 | This computes the a list of the Class's ancestors in the same order |
330 | in which method dispatch will be done. |
331 | |
332 | =back |
333 | |
334 | =head2 Methods |
335 | |
336 | =over 4 |
337 | |
338 | =item B<add_method ($method_name, $method)> |
339 | |
340 | This will take a C<$method_name> and CODE reference to that |
341 | C<$method> and install it into the Class. |
342 | |
343 | B<NOTE> : This does absolutely nothing special to C<$method> |
344 | other than use B<Sub::Name> to make sure it is tagged with the |
345 | correct name, and therefore show up correctly in stack traces and |
346 | such. |
347 | |
348 | =item B<has_method ($method_name)> |
349 | |
350 | This just provides a simple way to check if the Class implements |
351 | a specific C<$method_name>. It will I<not> however, attempt to check |
352 | if the class inherits the method. |
353 | |
354 | This will correctly handle functions defined outside of the package |
355 | that use a fully qualified name (C<sub Package::name { ... }>). |
356 | |
357 | This will correctly handle functions renamed with B<Sub::Name> and |
358 | installed using the symbol tables. However, if you are naming the |
359 | subroutine outside of the package scope, you must use the fully |
360 | qualified name, including the package name, for C<has_method> to |
361 | correctly identify it. |
362 | |
363 | This will attempt to correctly ignore functions imported from other |
364 | packages using B<Exporter>. It breaks down if the function imported |
365 | is an C<__ANON__> sub (such as with C<use constant>), which very well |
366 | may be a valid method being applied to the class. |
367 | |
368 | In short, this method cannot always be trusted to determine if the |
369 | C<$method_name> is actually a method. However, it will DWIM about |
370 | 90% of the time, so it's a small trade off IMO. |
371 | |
372 | =item B<get_method ($method_name)> |
373 | |
374 | This will return a CODE reference of the specified C<$method_name>, |
375 | or return undef if that method does not exist. |
376 | |
377 | =item B<remove_method ($method_name)> |
378 | |
379 | This will attempt to remove a given C<$method_name> from the Class. |
380 | It will return the CODE reference that it has removed, and will |
381 | attempt to use B<Sub::Name> to clear the methods associated name. |
382 | |
383 | =item B<get_method_list> |
384 | |
385 | This will return a list of method names for all I<locally> defined |
386 | methods. It does B<not> provide a list of all applicable methods, |
387 | including any inherited ones. If you want a list of all applicable |
388 | methods, use the C<compute_all_applicable_methods> method. |
389 | |
390 | =item B<compute_all_applicable_methods> |
391 | |
392 | This will return a list of all the methods names this Class will |
393 | support, taking into account inheritance. The list will be a list of |
394 | HASH references, each one containing the following information; method |
395 | name, the name of the class in which the method lives and a CODE |
396 | reference for the actual method. |
397 | |
398 | =item B<find_all_methods_by_name ($method_name)> |
399 | |
400 | This will traverse the inheritence hierarchy and locate all methods |
401 | with a given C<$method_name>. Similar to |
402 | C<compute_all_applicable_methods> it returns a list of HASH references |
403 | with the following information; method name (which will always be the |
404 | same as C<$method_name>), the name of the class in which the method |
405 | lives and a CODE reference for the actual method. |
406 | |
407 | The list of methods produced is a distinct list, meaning there are no |
408 | duplicates in it. This is especially useful for things like object |
409 | initialization and destruction where you only want the method called |
410 | once, and in the correct order. |
411 | |
412 | =back |
413 | |
414 | =head2 Attributes |
415 | |
416 | It should be noted that since there is no one consistent way to define |
417 | the attributes of a class in Perl 5. These methods can only work with |
418 | the information given, and can not easily discover information on |
419 | their own. |
420 | |
421 | =over 4 |
422 | |
423 | =item B<add_attribute ($attribute_name, $attribute_meta_object)> |
424 | |
425 | This stores a C<$attribute_meta_object> in the Class object and |
426 | associates it with the C<$attribute_name>. Unlike methods, attributes |
427 | within the MOP are stored as meta-information only. They will be used |
428 | later to construct instances from (see C<construct_instance> above). |
429 | More details about the attribute meta-objects can be found in the |
430 | L<The Attribute protocol> section of this document. |
431 | |
432 | =item B<has_attribute ($attribute_name)> |
433 | |
434 | Checks to see if this Class has an attribute by the name of |
435 | C<$attribute_name> and returns a boolean. |
436 | |
437 | =item B<get_attribute ($attribute_name)> |
438 | |
439 | Returns the attribute meta-object associated with C<$attribute_name>, |
440 | if none is found, it will return undef. |
441 | |
442 | =item B<remove_attribute ($attribute_name)> |
443 | |
444 | This will remove the attribute meta-object stored at |
445 | C<$attribute_name>, then return the removed attribute meta-object. |
446 | |
447 | B<NOTE:> Removing an attribute will only affect future instances of |
448 | the class, it will not make any attempt to remove the attribute from |
449 | any existing instances of the class. |
450 | |
451 | =item B<get_attribute_list> |
452 | |
453 | This returns a list of attribute names which are defined in the local |
454 | class. If you want a list of all applicable attributes for a class, |
455 | use the C<compute_all_applicable_attributes> method. |
456 | |
457 | =item B<compute_all_applicable_attributes> |
458 | |
459 | This will traverse the inheritance heirachy and return a list of HASH |
460 | references for all the applicable attributes for this class. The HASH |
461 | references will contain the following information; the attribute name, |
462 | the class which the attribute is associated with and the actual |
463 | attribute meta-object |
464 | |
465 | =item B<create_all_accessors> |
466 | |
467 | This will communicate with all of the classes attributes to create |
468 | and install the appropriate accessors. (see L<The Attribute Protocol> |
469 | below for more details). |
470 | |
471 | =back |
472 | |
8b978dd5 |
473 | =head1 AUTHOR |
474 | |
475 | Stevan Little E<gt>stevan@iinteractive.comE<lt> |
476 | |
477 | =head1 COPYRIGHT AND LICENSE |
478 | |
479 | Copyright 2006 by Infinity Interactive, Inc. |
480 | |
481 | L<http://www.iinteractive.com> |
482 | |
483 | This library is free software; you can redistribute it and/or modify |
484 | it under the same terms as Perl itself. |
485 | |
486 | =cut |