Commit | Line | Data |
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 | |
2eb717d5 |
14 | # Self-introspection |
15 | |
16 | sub meta { $_[0]->initialize($_[0]) } |
17 | |
8b978dd5 |
18 | # Creation |
19 | |
bfe4d0fc |
20 | { |
21 | # Metaclasses are singletons, so we cache them here. |
22 | # there is no need to worry about destruction though |
23 | # because they should die only when the program dies. |
24 | # After all, do package definitions even get reaped? |
25 | my %METAS; |
26 | sub initialize { |
27 | my ($class, $package_name) = @_; |
28 | (defined $package_name && $package_name) |
29 | || confess "You must pass a package name"; |
e16da3e6 |
30 | $METAS{$package_name} ||= bless { |
31 | '$:pkg' => $package_name, |
32 | '%:attrs' => {} |
33 | } => blessed($class) || $class; |
bfe4d0fc |
34 | } |
8b978dd5 |
35 | } |
36 | |
37 | sub create { |
38 | my ($class, $package_name, $package_version, %options) = @_; |
bfe4d0fc |
39 | (defined $package_name && $package_name) |
8b978dd5 |
40 | || confess "You must pass a package name"; |
41 | my $code = "package $package_name;"; |
42 | $code .= "\$$package_name\:\:VERSION = '$package_version';" |
43 | if defined $package_version; |
44 | eval $code; |
45 | confess "creation of $package_name failed : $@" if $@; |
bfe4d0fc |
46 | my $meta = $class->initialize($package_name); |
8b978dd5 |
47 | $meta->superclasses(@{$options{superclasses}}) |
48 | if exists $options{superclasses}; |
2eb717d5 |
49 | # NOTE: |
50 | # process attributes first, so that they can |
51 | # install accessors, but locally defined methods |
52 | # can then overwrite them. It is maybe a little odd, but |
53 | # I think this should be the order of things. |
54 | if (exists $options{attributes}) { |
cbd9f942 |
55 | foreach my $attr (@{$options{attributes}}) { |
56 | $meta->add_attribute($attr); |
2eb717d5 |
57 | } |
58 | } |
bfe4d0fc |
59 | if (exists $options{methods}) { |
60 | foreach my $method_name (keys %{$options{methods}}) { |
61 | $meta->add_method($method_name, $options{methods}->{$method_name}); |
62 | } |
2eb717d5 |
63 | } |
8b978dd5 |
64 | return $meta; |
65 | } |
66 | |
e16da3e6 |
67 | # Instance Construction |
68 | |
69 | sub construct_instance { |
cbd9f942 |
70 | my ($class, %params) = @_; |
71 | my $instance = {}; |
72 | foreach my $attr (map { $_->{attribute} } $class->compute_all_applicable_attributes()) { |
73 | # if the attr has an init_arg, use that, otherwise, |
74 | # use the attributes name itself as the init_arg |
75 | my $init_arg = $attr->has_init_arg() ? $attr->init_arg() : $attr->name; |
76 | # try to fetch the init arg from the %params ... |
77 | my $val; |
78 | $val = $params{$init_arg} if exists $params{$init_arg}; |
79 | # if nothing was in the %params, we can use the |
80 | # attribute's default value (if it has one) |
81 | $val ||= $attr->default() if $attr->has_default(); |
82 | # now add this to the instance structure |
83 | $instance->{$attr->name} = $val; |
84 | } |
85 | return $instance; |
e16da3e6 |
86 | } |
87 | |
8b978dd5 |
88 | # Informational |
89 | |
e16da3e6 |
90 | sub name { $_[0]->{'$:pkg'} } |
8b978dd5 |
91 | |
92 | sub version { |
93 | my $self = shift; |
94 | no strict 'refs'; |
95 | ${$self->name . '::VERSION'}; |
96 | } |
97 | |
98 | # Inheritance |
99 | |
100 | sub superclasses { |
101 | my $self = shift; |
102 | no strict 'refs'; |
103 | if (@_) { |
104 | my @supers = @_; |
105 | @{$self->name . '::ISA'} = @supers; |
106 | } |
107 | @{$self->name . '::ISA'}; |
108 | } |
109 | |
110 | sub class_precedence_list { |
111 | my $self = shift; |
bfe4d0fc |
112 | # NOTE: |
113 | # We need to check for ciruclar inheirtance here. |
114 | # This will do nothing if all is well, and blow |
115 | # up otherwise. Yes, it's an ugly hack, better |
116 | # suggestions are welcome. |
117 | { $self->name->isa('This is a test for circular inheritance') } |
118 | # ... and no back to our regularly scheduled program |
8b978dd5 |
119 | ( |
120 | $self->name, |
121 | map { |
bfe4d0fc |
122 | $self->initialize($_)->class_precedence_list() |
8b978dd5 |
123 | } $self->superclasses() |
124 | ); |
125 | } |
126 | |
0882828e |
127 | ## Methods |
128 | |
129 | sub add_method { |
130 | my ($self, $method_name, $method) = @_; |
131 | (defined $method_name && $method_name) |
132 | || confess "You must define a method name"; |
a5eca695 |
133 | # use reftype here to allow for blessed subs ... |
0882828e |
134 | (reftype($method) && reftype($method) eq 'CODE') |
135 | || confess "Your code block must be a CODE reference"; |
136 | my $full_method_name = ($self->name . '::' . $method_name); |
137 | |
138 | no strict 'refs'; |
c9b8b7f9 |
139 | no warnings 'redefine'; |
0882828e |
140 | *{$full_method_name} = subname $full_method_name => $method; |
141 | } |
142 | |
bfe4d0fc |
143 | { |
144 | |
145 | ## private utility functions for has_method |
2eb717d5 |
146 | my $_find_subroutine_package_name = sub { eval { svref_2object($_[0])->GV->STASH->NAME } || '' }; |
147 | my $_find_subroutine_name = sub { eval { svref_2object($_[0])->GV->NAME } || '' }; |
bfe4d0fc |
148 | |
149 | sub has_method { |
c9b8b7f9 |
150 | my ($self, $method_name) = @_; |
bfe4d0fc |
151 | (defined $method_name && $method_name) |
152 | || confess "You must define a method name"; |
0882828e |
153 | |
bfe4d0fc |
154 | my $sub_name = ($self->name . '::' . $method_name); |
0882828e |
155 | |
bfe4d0fc |
156 | no strict 'refs'; |
157 | return 0 if !defined(&{$sub_name}); |
158 | return 0 if $_find_subroutine_package_name->(\&{$sub_name}) ne $self->name && |
159 | $_find_subroutine_name->(\&{$sub_name}) ne '__ANON__'; |
160 | return 1; |
161 | } |
162 | |
0882828e |
163 | } |
164 | |
165 | sub get_method { |
c9b8b7f9 |
166 | my ($self, $method_name) = @_; |
0882828e |
167 | (defined $method_name && $method_name) |
168 | || confess "You must define a method name"; |
169 | |
170 | no strict 'refs'; |
171 | return \&{$self->name . '::' . $method_name} |
bfe4d0fc |
172 | if $self->has_method($method_name); |
c9b8b7f9 |
173 | return; # <- make sure to return undef |
174 | } |
175 | |
176 | sub remove_method { |
177 | my ($self, $method_name) = @_; |
178 | (defined $method_name && $method_name) |
179 | || confess "You must define a method name"; |
180 | |
181 | my $removed_method = $self->get_method($method_name); |
182 | |
183 | no strict 'refs'; |
184 | delete ${$self->name . '::'}{$method_name} |
185 | if defined $removed_method; |
186 | |
187 | return $removed_method; |
188 | } |
189 | |
190 | sub get_method_list { |
191 | my $self = shift; |
192 | no strict 'refs'; |
a5eca695 |
193 | grep { $self->has_method($_) } %{$self->name . '::'}; |
194 | } |
195 | |
196 | sub compute_all_applicable_methods { |
197 | my $self = shift; |
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, %seen_method); |
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 | foreach my $method_name ($meta->get_method_list()) { |
210 | next if exists $seen_method{$method_name}; |
211 | $seen_method{$method_name}++; |
212 | push @methods => { |
213 | name => $method_name, |
214 | class => $class, |
215 | code => $meta->get_method($method_name) |
216 | }; |
217 | } |
218 | } |
219 | return @methods; |
220 | } |
221 | |
a5eca695 |
222 | sub find_all_methods_by_name { |
223 | my ($self, $method_name) = @_; |
224 | (defined $method_name && $method_name) |
225 | || confess "You must define a method name to find"; |
226 | my @methods; |
227 | # keep a record of what we have seen |
228 | # here, this will handle all the |
229 | # inheritence issues because we are |
230 | # using the &class_precedence_list |
231 | my %seen_class; |
232 | foreach my $class ($self->class_precedence_list()) { |
233 | next if $seen_class{$class}; |
234 | $seen_class{$class}++; |
235 | # fetch the meta-class ... |
236 | my $meta = $self->initialize($class); |
237 | push @methods => { |
238 | name => $method_name, |
239 | class => $class, |
240 | code => $meta->get_method($method_name) |
241 | } if $meta->has_method($method_name); |
242 | } |
243 | return @methods; |
244 | |
8b978dd5 |
245 | } |
246 | |
552e3d24 |
247 | ## Attributes |
248 | |
e16da3e6 |
249 | sub add_attribute { |
2eb717d5 |
250 | my ($self,$attribute) = @_; |
e16da3e6 |
251 | (blessed($attribute) && $attribute->isa('Class::MOP::Attribute')) |
252 | || confess "Your attribute must be an instance of Class::MOP::Attribute (or a subclass)"; |
2eb717d5 |
253 | $attribute->install_accessors($self); |
254 | $self->{'%:attrs'}->{$attribute->name} = $attribute; |
e16da3e6 |
255 | } |
256 | |
257 | sub has_attribute { |
258 | my ($self, $attribute_name) = @_; |
259 | (defined $attribute_name && $attribute_name) |
260 | || confess "You must define an attribute name"; |
261 | exists $self->{'%:attrs'}->{$attribute_name} ? 1 : 0; |
262 | } |
263 | |
264 | sub get_attribute { |
265 | my ($self, $attribute_name) = @_; |
266 | (defined $attribute_name && $attribute_name) |
267 | || confess "You must define an attribute name"; |
268 | return $self->{'%:attrs'}->{$attribute_name} |
269 | if $self->has_attribute($attribute_name); |
270 | } |
271 | |
272 | sub remove_attribute { |
273 | my ($self, $attribute_name) = @_; |
274 | (defined $attribute_name && $attribute_name) |
275 | || confess "You must define an attribute name"; |
276 | my $removed_attribute = $self->{'%:attrs'}->{$attribute_name}; |
277 | delete $self->{'%:attrs'}->{$attribute_name} |
278 | if defined $removed_attribute; |
2eb717d5 |
279 | $removed_attribute->remove_accessors($self); |
e16da3e6 |
280 | return $removed_attribute; |
281 | } |
282 | |
283 | sub get_attribute_list { |
284 | my $self = shift; |
285 | keys %{$self->{'%:attrs'}}; |
286 | } |
287 | |
288 | sub compute_all_applicable_attributes { |
289 | my $self = shift; |
290 | my @attrs; |
291 | # keep a record of what we have seen |
292 | # here, this will handle all the |
293 | # inheritence issues because we are |
294 | # using the &class_precedence_list |
295 | my (%seen_class, %seen_attr); |
296 | foreach my $class ($self->class_precedence_list()) { |
297 | next if $seen_class{$class}; |
298 | $seen_class{$class}++; |
299 | # fetch the meta-class ... |
300 | my $meta = $self->initialize($class); |
301 | foreach my $attr_name ($meta->get_attribute_list()) { |
302 | next if exists $seen_attr{$attr_name}; |
303 | $seen_attr{$attr_name}++; |
304 | push @attrs => { |
305 | name => $attr_name, |
306 | class => $class, |
307 | attribute => $meta->get_attribute($attr_name) |
308 | }; |
309 | } |
310 | } |
311 | return @attrs; |
312 | } |
2eb717d5 |
313 | |
552e3d24 |
314 | |
8b978dd5 |
315 | 1; |
316 | |
317 | __END__ |
318 | |
319 | =pod |
320 | |
321 | =head1 NAME |
322 | |
323 | Class::MOP::Class - Class Meta Object |
324 | |
325 | =head1 SYNOPSIS |
326 | |
327 | =head1 DESCRIPTION |
328 | |
552e3d24 |
329 | =head1 METHODS |
330 | |
2eb717d5 |
331 | =head2 Self Introspection |
332 | |
333 | =over 4 |
334 | |
335 | =item B<meta> |
336 | |
337 | This allows Class::MOP::Class to actually introspect itself. |
338 | |
339 | =back |
340 | |
552e3d24 |
341 | =head2 Class construction |
342 | |
343 | These methods handle creating Class objects, which can be used to |
344 | both create new classes, and analyze pre-existing ones. |
345 | |
346 | This module will internally store references to all the instances |
347 | you create with these methods, so that they do not need to be |
348 | created any more than nessecary. Basically, they are singletons. |
349 | |
350 | =over 4 |
351 | |
352 | =item B<create ($package_name, ?$package_version, |
353 | superclasses => ?@superclasses, |
354 | methods => ?%methods, |
355 | attributes => ?%attributes)> |
356 | |
357 | This returns the basic Class object, bringing the specified |
358 | C<$package_name> into existence and adding any of the |
359 | C<$package_version>, C<@superclasses>, C<%methods> and C<%attributes> |
360 | to it. |
361 | |
362 | =item B<initialize ($package_name)> |
363 | |
364 | This initializes a Class object for a given a C<$package_name>. |
365 | |
366 | =back |
367 | |
368 | =head2 Instance construction |
369 | |
370 | =over 4 |
371 | |
cbd9f942 |
372 | =item B<construct_instance (%params)> |
552e3d24 |
373 | |
cbd9f942 |
374 | This will construct and instance using a HASH ref as storage |
552e3d24 |
375 | (currently only HASH references are supported). This will collect all |
376 | the applicable attribute meta-objects and layout out the fields in the |
cbd9f942 |
377 | HASH ref, it will then initialize them using either use the |
552e3d24 |
378 | corresponding key in C<%params> or any default value or initializer |
379 | found in the attribute meta-object. |
380 | |
381 | =back |
382 | |
383 | =head2 Informational |
384 | |
385 | =over 4 |
386 | |
387 | =item B<name> |
388 | |
389 | This is a read-only attribute which returns the package name that |
390 | the Class is stored in. |
391 | |
392 | =item B<version> |
393 | |
394 | This is a read-only attribute which returns the C<$VERSION> of the |
395 | package the Class is stored in. |
396 | |
397 | =back |
398 | |
399 | =head2 Inheritance Relationships |
400 | |
401 | =over 4 |
402 | |
403 | =item B<superclasses (?@superclasses)> |
404 | |
405 | This is a read-write attribute which represents the superclass |
406 | relationships of this Class. Basically, it can get and set the |
407 | C<@ISA> for you. |
408 | |
409 | =item B<class_precedence_list> |
410 | |
411 | This computes the a list of the Class's ancestors in the same order |
412 | in which method dispatch will be done. |
413 | |
414 | =back |
415 | |
416 | =head2 Methods |
417 | |
418 | =over 4 |
419 | |
420 | =item B<add_method ($method_name, $method)> |
421 | |
422 | This will take a C<$method_name> and CODE reference to that |
423 | C<$method> and install it into the Class. |
424 | |
425 | B<NOTE> : This does absolutely nothing special to C<$method> |
426 | other than use B<Sub::Name> to make sure it is tagged with the |
427 | correct name, and therefore show up correctly in stack traces and |
428 | such. |
429 | |
430 | =item B<has_method ($method_name)> |
431 | |
432 | This just provides a simple way to check if the Class implements |
433 | a specific C<$method_name>. It will I<not> however, attempt to check |
434 | if the class inherits the method. |
435 | |
436 | This will correctly handle functions defined outside of the package |
437 | that use a fully qualified name (C<sub Package::name { ... }>). |
438 | |
439 | This will correctly handle functions renamed with B<Sub::Name> and |
440 | installed using the symbol tables. However, if you are naming the |
441 | subroutine outside of the package scope, you must use the fully |
442 | qualified name, including the package name, for C<has_method> to |
443 | correctly identify it. |
444 | |
445 | This will attempt to correctly ignore functions imported from other |
446 | packages using B<Exporter>. It breaks down if the function imported |
447 | is an C<__ANON__> sub (such as with C<use constant>), which very well |
448 | may be a valid method being applied to the class. |
449 | |
450 | In short, this method cannot always be trusted to determine if the |
451 | C<$method_name> is actually a method. However, it will DWIM about |
452 | 90% of the time, so it's a small trade off IMO. |
453 | |
454 | =item B<get_method ($method_name)> |
455 | |
456 | This will return a CODE reference of the specified C<$method_name>, |
457 | or return undef if that method does not exist. |
458 | |
459 | =item B<remove_method ($method_name)> |
460 | |
461 | This will attempt to remove a given C<$method_name> from the Class. |
462 | It will return the CODE reference that it has removed, and will |
463 | attempt to use B<Sub::Name> to clear the methods associated name. |
464 | |
465 | =item B<get_method_list> |
466 | |
467 | This will return a list of method names for all I<locally> defined |
468 | methods. It does B<not> provide a list of all applicable methods, |
469 | including any inherited ones. If you want a list of all applicable |
470 | methods, use the C<compute_all_applicable_methods> method. |
471 | |
472 | =item B<compute_all_applicable_methods> |
473 | |
474 | This will return a list of all the methods names this Class will |
475 | support, taking into account inheritance. The list will be a list of |
476 | HASH references, each one containing the following information; method |
477 | name, the name of the class in which the method lives and a CODE |
478 | reference for the actual method. |
479 | |
480 | =item B<find_all_methods_by_name ($method_name)> |
481 | |
482 | This will traverse the inheritence hierarchy and locate all methods |
483 | with a given C<$method_name>. Similar to |
484 | C<compute_all_applicable_methods> it returns a list of HASH references |
485 | with the following information; method name (which will always be the |
486 | same as C<$method_name>), the name of the class in which the method |
487 | lives and a CODE reference for the actual method. |
488 | |
489 | The list of methods produced is a distinct list, meaning there are no |
490 | duplicates in it. This is especially useful for things like object |
491 | initialization and destruction where you only want the method called |
492 | once, and in the correct order. |
493 | |
494 | =back |
495 | |
496 | =head2 Attributes |
497 | |
498 | It should be noted that since there is no one consistent way to define |
499 | the attributes of a class in Perl 5. These methods can only work with |
500 | the information given, and can not easily discover information on |
501 | their own. |
502 | |
503 | =over 4 |
504 | |
505 | =item B<add_attribute ($attribute_name, $attribute_meta_object)> |
506 | |
507 | This stores a C<$attribute_meta_object> in the Class object and |
508 | associates it with the C<$attribute_name>. Unlike methods, attributes |
509 | within the MOP are stored as meta-information only. They will be used |
510 | later to construct instances from (see C<construct_instance> above). |
511 | More details about the attribute meta-objects can be found in the |
512 | L<The Attribute protocol> section of this document. |
513 | |
514 | =item B<has_attribute ($attribute_name)> |
515 | |
516 | Checks to see if this Class has an attribute by the name of |
517 | C<$attribute_name> and returns a boolean. |
518 | |
519 | =item B<get_attribute ($attribute_name)> |
520 | |
521 | Returns the attribute meta-object associated with C<$attribute_name>, |
522 | if none is found, it will return undef. |
523 | |
524 | =item B<remove_attribute ($attribute_name)> |
525 | |
526 | This will remove the attribute meta-object stored at |
527 | C<$attribute_name>, then return the removed attribute meta-object. |
528 | |
529 | B<NOTE:> Removing an attribute will only affect future instances of |
530 | the class, it will not make any attempt to remove the attribute from |
531 | any existing instances of the class. |
532 | |
533 | =item B<get_attribute_list> |
534 | |
535 | This returns a list of attribute names which are defined in the local |
536 | class. If you want a list of all applicable attributes for a class, |
537 | use the C<compute_all_applicable_attributes> method. |
538 | |
539 | =item B<compute_all_applicable_attributes> |
540 | |
541 | This will traverse the inheritance heirachy and return a list of HASH |
542 | references for all the applicable attributes for this class. The HASH |
543 | references will contain the following information; the attribute name, |
544 | the class which the attribute is associated with and the actual |
2eb717d5 |
545 | attribute meta-object. |
552e3d24 |
546 | |
547 | =back |
548 | |
8b978dd5 |
549 | =head1 AUTHOR |
550 | |
551 | Stevan Little E<gt>stevan@iinteractive.comE<lt> |
552 | |
553 | =head1 COPYRIGHT AND LICENSE |
554 | |
555 | Copyright 2006 by Infinity Interactive, Inc. |
556 | |
557 | L<http://www.iinteractive.com> |
558 | |
559 | This library is free software; you can redistribute it and/or modify |
560 | it under the same terms as Perl itself. |
561 | |
562 | =cut |