Commit | Line | Data |
8b978dd5 |
1 | |
2 | package Class::MOP::Class; |
3 | |
4 | use strict; |
5 | use warnings; |
6 | |
7 | use Carp 'confess'; |
77e5fce4 |
8 | use Scalar::Util 'blessed', 'reftype', 'weaken'; |
8b978dd5 |
9 | use Sub::Name 'subname'; |
96ceced8 |
10 | use B 'svref_2object'; |
8b978dd5 |
11 | |
be7677c7 |
12 | our $VERSION = '0.18'; |
f0480c45 |
13 | our $AUTHORITY = 'cpan:STEVAN'; |
8b978dd5 |
14 | |
2243a22b |
15 | use base 'Class::MOP::Module'; |
16 | |
839ea973 |
17 | use Class::MOP::Instance; |
18 | |
aa448b16 |
19 | # Self-introspection |
2eb717d5 |
20 | |
aa448b16 |
21 | sub meta { Class::MOP::Class->initialize(blessed($_[0]) || $_[0]) } |
2eb717d5 |
22 | |
8b978dd5 |
23 | # Creation |
587aca23 |
24 | |
be7677c7 |
25 | sub initialize { |
26 | my $class = shift; |
27 | my $package_name = shift; |
28 | (defined $package_name && $package_name && !blessed($package_name)) |
29 | || confess "You must pass a package name and it cannot be blessed"; |
30 | $class->construct_class_instance(':package' => $package_name, @_); |
31 | } |
32 | |
33 | sub reinitialize { |
34 | my $class = shift; |
35 | my $package_name = shift; |
36 | (defined $package_name && $package_name && !blessed($package_name)) |
37 | || confess "You must pass a package name and it cannot be blessed"; |
38 | Class::MOP::remove_metaclass_by_name($package_name); |
39 | $class->construct_class_instance(':package' => $package_name, @_); |
40 | } |
651955fb |
41 | |
be7677c7 |
42 | # NOTE: (meta-circularity) |
43 | # this is a special form of &construct_instance |
44 | # (see below), which is used to construct class |
45 | # meta-object instances for any Class::MOP::* |
46 | # class. All other classes will use the more |
47 | # normal &construct_instance. |
48 | sub construct_class_instance { |
49 | my $class = shift; |
50 | my %options = @_; |
51 | my $package_name = $options{':package'}; |
52 | (defined $package_name && $package_name) |
53 | || confess "You must pass a package name"; |
54 | # NOTE: |
55 | # return the metaclass if we have it cached, |
56 | # and it is still defined (it has not been |
57 | # reaped by DESTROY yet, which can happen |
58 | # annoyingly enough during global destruction) |
59 | return Class::MOP::get_metaclass_by_name($package_name) |
60 | if Class::MOP::does_metaclass_exist($package_name); |
61 | |
62 | # NOTE: |
63 | # we need to deal with the possibility |
64 | # of class immutability here, and then |
65 | # get the name of the class appropriately |
66 | $class = (blessed($class) |
67 | ? ($class->is_immutable |
68 | ? $class->get_mutable_metaclass_name() |
69 | : blessed($class)) |
70 | : $class); |
71 | |
72 | $class = blessed($class) || $class; |
73 | # now create the metaclass |
74 | my $meta; |
75 | if ($class =~ /^Class::MOP::Class$/) { |
76 | no strict 'refs'; |
77 | $meta = bless { |
78 | # inherited from Class::MOP::Package |
79 | '$:package' => $package_name, |
80 | '%:namespace' => \%{$package_name . '::'}, |
81 | # inherited from Class::MOP::Module |
82 | '$:version' => (exists ${$package_name . '::'}{'VERSION'} ? ${$package_name . '::VERSION'} : undef), |
83 | '$:authority' => (exists ${$package_name . '::'}{'AUTHORITY'} ? ${$package_name . '::AUTHORITY'} : undef), |
84 | # defined here ... |
85 | '%:attributes' => {}, |
86 | '$:attribute_metaclass' => $options{':attribute_metaclass'} || 'Class::MOP::Attribute', |
87 | '$:method_metaclass' => $options{':method_metaclass'} || 'Class::MOP::Method', |
88 | '$:instance_metaclass' => $options{':instance_metaclass'} || 'Class::MOP::Instance', |
89 | } => $class; |
90 | } |
91 | else { |
92 | # NOTE: |
93 | # it is safe to use meta here because |
94 | # class will always be a subclass of |
95 | # Class::MOP::Class, which defines meta |
96 | $meta = $class->meta->construct_instance(%options) |
727919c5 |
97 | } |
98 | |
be7677c7 |
99 | # and check the metaclass compatibility |
100 | $meta->check_metaclass_compatability(); |
ff43b9d6 |
101 | |
be7677c7 |
102 | Class::MOP::store_metaclass_by_name($package_name, $meta); |
b9d9fc0b |
103 | |
be7677c7 |
104 | # NOTE: |
105 | # we need to weaken any anon classes |
106 | # so that they can call DESTROY properly |
b9d9fc0b |
107 | Class::MOP::weaken_metaclass($package_name) if $meta->is_anon_class; |
108 | |
be7677c7 |
109 | $meta; |
110 | } |
111 | |
112 | sub check_metaclass_compatability { |
113 | my $self = shift; |
114 | |
115 | # this is always okay ... |
116 | return if blessed($self) eq 'Class::MOP::Class' && |
117 | $self->instance_metaclass eq 'Class::MOP::Instance'; |
118 | |
119 | my @class_list = $self->class_precedence_list; |
120 | shift @class_list; # shift off $self->name |
373a16ae |
121 | |
be7677c7 |
122 | foreach my $class_name (@class_list) { |
123 | my $meta = Class::MOP::get_metaclass_by_name($class_name) || next; |
124 | |
373a16ae |
125 | # NOTE: |
126 | # we need to deal with the possibility |
127 | # of class immutability here, and then |
be7677c7 |
128 | # get the name of the class appropriately |
129 | my $meta_type = ($meta->is_immutable |
130 | ? $meta->get_mutable_metaclass_name() |
131 | : blessed($meta)); |
132 | |
133 | ($self->isa($meta_type)) |
134 | || confess $self->name . "->meta => (" . (blessed($self)) . ")" . |
135 | " is not compatible with the " . |
136 | $class_name . "->meta => (" . ($meta_type) . ")"; |
77e5fce4 |
137 | # NOTE: |
be7677c7 |
138 | # we also need to check that instance metaclasses |
139 | # are compatabile in the same the class. |
140 | ($self->instance_metaclass->isa($meta->instance_metaclass)) |
141 | || confess $self->name . "->meta => (" . ($self->instance_metaclass) . ")" . |
142 | " is not compatible with the " . |
143 | $class_name . "->meta => (" . ($meta->instance_metaclass) . ")"; |
144 | } |
145 | } |
8b978dd5 |
146 | |
6d5355c3 |
147 | ## ANON classes |
148 | |
149 | { |
150 | # NOTE: |
151 | # this should be sufficient, if you have a |
152 | # use case where it is not, write a test and |
153 | # I will change it. |
154 | my $ANON_CLASS_SERIAL = 0; |
b9d9fc0b |
155 | |
156 | # NOTE: |
157 | # we need a sufficiently annoying prefix |
158 | # this should suffice for now, this is |
159 | # used in a couple of places below, so |
160 | # need to put it up here for now. |
161 | my $ANON_CLASS_PREFIX = 'Class::MOP::Class::__ANON__::SERIAL::'; |
162 | |
163 | sub is_anon_class { |
164 | my $self = shift; |
165 | $self->name =~ /^$ANON_CLASS_PREFIX/ ? 1 : 0; |
166 | } |
6d5355c3 |
167 | |
168 | sub create_anon_class { |
169 | my ($class, %options) = @_; |
170 | my $package_name = $ANON_CLASS_PREFIX . ++$ANON_CLASS_SERIAL; |
171 | return $class->create($package_name, '0.00', %options); |
b9d9fc0b |
172 | } |
6d5355c3 |
173 | |
b9d9fc0b |
174 | # NOTE: |
175 | # this will only get called for |
176 | # anon-classes, all other calls |
177 | # are assumed to occur during |
178 | # global destruction and so don't |
179 | # really need to be handled explicitly |
180 | sub DESTROY { |
181 | my $self = shift; |
182 | return unless $self->name =~ /^$ANON_CLASS_PREFIX/; |
183 | my ($serial_id) = ($self->name =~ /^$ANON_CLASS_PREFIX(\d+)/); |
184 | no strict 'refs'; |
185 | foreach my $key (keys %{$ANON_CLASS_PREFIX . $serial_id}) { |
186 | delete ${$ANON_CLASS_PREFIX . $serial_id}{$key}; |
187 | } |
188 | delete ${'main::' . $ANON_CLASS_PREFIX}{$serial_id . '::'}; |
6d5355c3 |
189 | } |
b9d9fc0b |
190 | |
6d5355c3 |
191 | } |
192 | |
193 | # creating classes with MOP ... |
194 | |
8b978dd5 |
195 | sub create { |
196 | my ($class, $package_name, $package_version, %options) = @_; |
bfe4d0fc |
197 | (defined $package_name && $package_name) |
8b978dd5 |
198 | || confess "You must pass a package name"; |
199 | my $code = "package $package_name;"; |
200 | $code .= "\$$package_name\:\:VERSION = '$package_version';" |
201 | if defined $package_version; |
202 | eval $code; |
203 | confess "creation of $package_name failed : $@" if $@; |
bfe4d0fc |
204 | my $meta = $class->initialize($package_name); |
aa448b16 |
205 | |
206 | $meta->add_method('meta' => sub { |
df7b4119 |
207 | $class->initialize(blessed($_[0]) || $_[0]); |
aa448b16 |
208 | }); |
209 | |
8b978dd5 |
210 | $meta->superclasses(@{$options{superclasses}}) |
211 | if exists $options{superclasses}; |
2eb717d5 |
212 | # NOTE: |
213 | # process attributes first, so that they can |
214 | # install accessors, but locally defined methods |
215 | # can then overwrite them. It is maybe a little odd, but |
216 | # I think this should be the order of things. |
217 | if (exists $options{attributes}) { |
cbd9f942 |
218 | foreach my $attr (@{$options{attributes}}) { |
219 | $meta->add_attribute($attr); |
2eb717d5 |
220 | } |
221 | } |
bfe4d0fc |
222 | if (exists $options{methods}) { |
223 | foreach my $method_name (keys %{$options{methods}}) { |
224 | $meta->add_method($method_name, $options{methods}->{$method_name}); |
225 | } |
2eb717d5 |
226 | } |
8b978dd5 |
227 | return $meta; |
228 | } |
229 | |
7b31baf4 |
230 | ## Attribute readers |
231 | |
232 | # NOTE: |
233 | # all these attribute readers will be bootstrapped |
234 | # away in the Class::MOP bootstrap section |
235 | |
7b31baf4 |
236 | sub get_attribute_map { $_[0]->{'%:attributes'} } |
237 | sub attribute_metaclass { $_[0]->{'$:attribute_metaclass'} } |
238 | sub method_metaclass { $_[0]->{'$:method_metaclass'} } |
2bab2be6 |
239 | sub instance_metaclass { $_[0]->{'$:instance_metaclass'} } |
7b31baf4 |
240 | |
c9e77dbb |
241 | # Instance Construction & Cloning |
242 | |
5f3c057a |
243 | sub new_object { |
244 | my $class = shift; |
651955fb |
245 | # NOTE: |
246 | # we need to protect the integrity of the |
247 | # Class::MOP::Class singletons here, so we |
248 | # delegate this to &construct_class_instance |
249 | # which will deal with the singletons |
250 | return $class->construct_class_instance(@_) |
251 | if $class->name->isa('Class::MOP::Class'); |
24869f62 |
252 | return $class->construct_instance(@_); |
5f3c057a |
253 | } |
e16da3e6 |
254 | |
255 | sub construct_instance { |
cbd9f942 |
256 | my ($class, %params) = @_; |
0e76a376 |
257 | my $meta_instance = $class->get_meta_instance(); |
258 | my $instance = $meta_instance->create_instance(); |
c9e77dbb |
259 | foreach my $attr ($class->compute_all_applicable_attributes()) { |
f892c0f0 |
260 | $attr->initialize_instance_slot($meta_instance, $instance, \%params); |
cbd9f942 |
261 | } |
2d711cc8 |
262 | return $instance; |
263 | } |
264 | |
265 | sub get_meta_instance { |
266 | my $class = shift; |
052c2a1a |
267 | return $class->instance_metaclass->new( |
268 | $class, |
269 | $class->compute_all_applicable_attributes() |
270 | ); |
e16da3e6 |
271 | } |
272 | |
5f3c057a |
273 | sub clone_object { |
274 | my $class = shift; |
7b31baf4 |
275 | my $instance = shift; |
651955fb |
276 | (blessed($instance) && $instance->isa($class->name)) |
277 | || confess "You must pass an instance ($instance) of the metaclass (" . $class->name . ")"; |
278 | # NOTE: |
279 | # we need to protect the integrity of the |
280 | # Class::MOP::Class singletons here, they |
a740253a |
281 | # should not be cloned. |
651955fb |
282 | return $instance if $instance->isa('Class::MOP::Class'); |
f7259199 |
283 | $class->clone_instance($instance, @_); |
5f3c057a |
284 | } |
285 | |
c9e77dbb |
286 | sub clone_instance { |
651955fb |
287 | my ($class, $instance, %params) = @_; |
288 | (blessed($instance)) |
c9e77dbb |
289 | || confess "You can only clone instances, \$self is not a blessed instance"; |
f7259199 |
290 | my $meta_instance = $class->get_meta_instance(); |
291 | my $clone = $meta_instance->clone_instance($instance); |
11977e43 |
292 | foreach my $key (keys %params) { |
f7259199 |
293 | next unless $meta_instance->is_valid_slot($key); |
294 | $meta_instance->set_slot_value($clone, $key, $params{$key}); |
295 | } |
c9e77dbb |
296 | return $clone; |
297 | } |
298 | |
8b978dd5 |
299 | # Inheritance |
300 | |
301 | sub superclasses { |
302 | my $self = shift; |
8b978dd5 |
303 | if (@_) { |
304 | my @supers = @_; |
9d6dce77 |
305 | @{$self->get_package_symbol('@ISA')} = @supers; |
d82060fe |
306 | # NOTE: |
307 | # we need to check the metaclass |
308 | # compatability here so that we can |
309 | # be sure that the superclass is |
310 | # not potentially creating an issues |
311 | # we don't know about |
312 | $self->check_metaclass_compatability(); |
8b978dd5 |
313 | } |
9d6dce77 |
314 | @{$self->get_package_symbol('@ISA')}; |
8b978dd5 |
315 | } |
316 | |
317 | sub class_precedence_list { |
318 | my $self = shift; |
bfe4d0fc |
319 | # NOTE: |
320 | # We need to check for ciruclar inheirtance here. |
321 | # This will do nothing if all is well, and blow |
322 | # up otherwise. Yes, it's an ugly hack, better |
323 | # suggestions are welcome. |
93b4e576 |
324 | { ($self->name || return)->isa('This is a test for circular inheritance') } |
8c936afc |
325 | # ... and now back to our regularly scheduled program |
8b978dd5 |
326 | ( |
327 | $self->name, |
328 | map { |
f7259199 |
329 | $self->initialize($_)->class_precedence_list() |
8b978dd5 |
330 | } $self->superclasses() |
331 | ); |
332 | } |
333 | |
0882828e |
334 | ## Methods |
335 | |
336 | sub add_method { |
337 | my ($self, $method_name, $method) = @_; |
338 | (defined $method_name && $method_name) |
339 | || confess "You must define a method name"; |
a5eca695 |
340 | # use reftype here to allow for blessed subs ... |
ee5e71d4 |
341 | ('CODE' eq (reftype($method) || '')) |
0882828e |
342 | || confess "Your code block must be a CODE reference"; |
343 | my $full_method_name = ($self->name . '::' . $method_name); |
de19f115 |
344 | |
9d6dce77 |
345 | # FIXME: |
346 | # dont bless subs, its bad mkay |
2d711cc8 |
347 | $method = $self->method_metaclass->wrap($method) unless blessed($method); |
348 | |
9d6dce77 |
349 | $self->add_package_symbol("&${method_name}" => subname $full_method_name => $method); |
0882828e |
350 | } |
351 | |
a4258ffd |
352 | { |
2d711cc8 |
353 | my $fetch_and_prepare_method = sub { |
354 | my ($self, $method_name) = @_; |
355 | # fetch it locally |
356 | my $method = $self->get_method($method_name); |
357 | # if we dont have local ... |
358 | unless ($method) { |
195f5bf8 |
359 | # try to find the next method |
360 | $method = $self->find_next_method_by_name($method_name); |
361 | # die if it does not exist |
362 | (defined $method) |
2d711cc8 |
363 | || confess "The method '$method_name' is not found in the inherience hierarchy for this class"; |
195f5bf8 |
364 | # and now make sure to wrap it |
365 | # even if it is already wrapped |
366 | # because we need a new sub ref |
2d711cc8 |
367 | $method = Class::MOP::Method::Wrapped->wrap($method); |
195f5bf8 |
368 | } |
369 | else { |
370 | # now make sure we wrap it properly |
371 | $method = Class::MOP::Method::Wrapped->wrap($method) |
372 | unless $method->isa('Class::MOP::Method::Wrapped'); |
373 | } |
374 | $self->add_method($method_name => $method); |
2d711cc8 |
375 | return $method; |
376 | }; |
377 | |
378 | sub add_before_method_modifier { |
379 | my ($self, $method_name, $method_modifier) = @_; |
380 | (defined $method_name && $method_name) |
381 | || confess "You must pass in a method name"; |
382 | my $method = $fetch_and_prepare_method->($self, $method_name); |
383 | $method->add_before_modifier(subname ':before' => $method_modifier); |
384 | } |
385 | |
386 | sub add_after_method_modifier { |
387 | my ($self, $method_name, $method_modifier) = @_; |
388 | (defined $method_name && $method_name) |
389 | || confess "You must pass in a method name"; |
390 | my $method = $fetch_and_prepare_method->($self, $method_name); |
391 | $method->add_after_modifier(subname ':after' => $method_modifier); |
392 | } |
393 | |
394 | sub add_around_method_modifier { |
395 | my ($self, $method_name, $method_modifier) = @_; |
396 | (defined $method_name && $method_name) |
397 | || confess "You must pass in a method name"; |
398 | my $method = $fetch_and_prepare_method->($self, $method_name); |
399 | $method->add_around_modifier(subname ':around' => $method_modifier); |
400 | } |
a4258ffd |
401 | |
8c936afc |
402 | # NOTE: |
403 | # the methods above used to be named like this: |
404 | # ${pkg}::${method}:(before|after|around) |
405 | # but this proved problematic when using one modifier |
406 | # to wrap multiple methods (something which is likely |
407 | # to happen pretty regularly IMO). So instead of naming |
408 | # it like this, I have chosen to just name them purely |
409 | # with their modifier names, like so: |
410 | # :(before|after|around) |
411 | # The fact is that in a stack trace, it will be fairly |
412 | # evident from the context what method they are attached |
413 | # to, and so don't need the fully qualified name. |
ee5e71d4 |
414 | } |
415 | |
663f8198 |
416 | sub alias_method { |
417 | my ($self, $method_name, $method) = @_; |
418 | (defined $method_name && $method_name) |
419 | || confess "You must define a method name"; |
420 | # use reftype here to allow for blessed subs ... |
ee5e71d4 |
421 | ('CODE' eq (reftype($method) || '')) |
663f8198 |
422 | || confess "Your code block must be a CODE reference"; |
de19f115 |
423 | |
9d6dce77 |
424 | # FIXME: |
425 | # dont bless subs, its bad mkay |
2d711cc8 |
426 | $method = $self->method_metaclass->wrap($method) unless blessed($method); |
663f8198 |
427 | |
9d6dce77 |
428 | $self->add_package_symbol("&${method_name}" => $method); |
663f8198 |
429 | } |
430 | |
16e960bd |
431 | sub find_method_by_name { |
9d6dce77 |
432 | my ($self, $method_name) = @_; |
433 | return $self->name->can($method_name); |
16e960bd |
434 | } |
435 | |
de19f115 |
436 | sub has_method { |
437 | my ($self, $method_name) = @_; |
438 | (defined $method_name && $method_name) |
439 | || confess "You must define a method name"; |
0882828e |
440 | |
9d6dce77 |
441 | return 0 if !$self->has_package_symbol("&${method_name}"); |
442 | my $method = $self->get_package_symbol("&${method_name}"); |
96ceced8 |
443 | return 0 if (svref_2object($method)->GV->STASH->NAME || '') ne $self->name && |
2d711cc8 |
444 | (svref_2object($method)->GV->NAME || '') ne '__ANON__'; |
16e960bd |
445 | |
9d6dce77 |
446 | # FIXME: |
447 | # dont bless subs, its bad mkay |
448 | $self->method_metaclass->wrap($method) unless blessed($method); |
449 | |
de19f115 |
450 | return 1; |
0882828e |
451 | } |
452 | |
453 | sub get_method { |
c9b8b7f9 |
454 | my ($self, $method_name) = @_; |
0882828e |
455 | (defined $method_name && $method_name) |
456 | || confess "You must define a method name"; |
457 | |
2d711cc8 |
458 | return unless $self->has_method($method_name); |
9d6dce77 |
459 | |
460 | return $self->get_package_symbol("&${method_name}"); |
c9b8b7f9 |
461 | } |
462 | |
463 | sub remove_method { |
464 | my ($self, $method_name) = @_; |
465 | (defined $method_name && $method_name) |
466 | || confess "You must define a method name"; |
467 | |
468 | my $removed_method = $self->get_method($method_name); |
469 | |
9d6dce77 |
470 | $self->remove_package_symbol("&${method_name}") |
c9b8b7f9 |
471 | if defined $removed_method; |
472 | |
473 | return $removed_method; |
474 | } |
475 | |
476 | sub get_method_list { |
477 | my $self = shift; |
9d6dce77 |
478 | grep { $self->has_method($_) } $self->list_all_package_symbols; |
a5eca695 |
479 | } |
480 | |
481 | sub compute_all_applicable_methods { |
482 | my $self = shift; |
483 | my @methods; |
484 | # keep a record of what we have seen |
485 | # here, this will handle all the |
486 | # inheritence issues because we are |
487 | # using the &class_precedence_list |
488 | my (%seen_class, %seen_method); |
489 | foreach my $class ($self->class_precedence_list()) { |
490 | next if $seen_class{$class}; |
491 | $seen_class{$class}++; |
492 | # fetch the meta-class ... |
493 | my $meta = $self->initialize($class); |
494 | foreach my $method_name ($meta->get_method_list()) { |
495 | next if exists $seen_method{$method_name}; |
496 | $seen_method{$method_name}++; |
497 | push @methods => { |
498 | name => $method_name, |
499 | class => $class, |
500 | code => $meta->get_method($method_name) |
501 | }; |
502 | } |
503 | } |
504 | return @methods; |
505 | } |
506 | |
a5eca695 |
507 | sub find_all_methods_by_name { |
508 | my ($self, $method_name) = @_; |
509 | (defined $method_name && $method_name) |
510 | || confess "You must define a method name to find"; |
511 | my @methods; |
512 | # keep a record of what we have seen |
513 | # here, this will handle all the |
514 | # inheritence issues because we are |
515 | # using the &class_precedence_list |
516 | my %seen_class; |
517 | foreach my $class ($self->class_precedence_list()) { |
518 | next if $seen_class{$class}; |
519 | $seen_class{$class}++; |
520 | # fetch the meta-class ... |
96ceced8 |
521 | my $meta = $self->initialize($class); |
a5eca695 |
522 | push @methods => { |
523 | name => $method_name, |
524 | class => $class, |
525 | code => $meta->get_method($method_name) |
526 | } if $meta->has_method($method_name); |
527 | } |
528 | return @methods; |
8b978dd5 |
529 | } |
530 | |
96ceced8 |
531 | sub find_next_method_by_name { |
532 | my ($self, $method_name) = @_; |
533 | (defined $method_name && $method_name) |
2d711cc8 |
534 | || confess "You must define a method name to find"; |
96ceced8 |
535 | # keep a record of what we have seen |
536 | # here, this will handle all the |
537 | # inheritence issues because we are |
538 | # using the &class_precedence_list |
539 | my %seen_class; |
2d711cc8 |
540 | my @cpl = $self->class_precedence_list(); |
541 | shift @cpl; # discard ourselves |
96ceced8 |
542 | foreach my $class (@cpl) { |
543 | next if $seen_class{$class}; |
544 | $seen_class{$class}++; |
545 | # fetch the meta-class ... |
546 | my $meta = $self->initialize($class); |
2d711cc8 |
547 | return $meta->get_method($method_name) |
548 | if $meta->has_method($method_name); |
96ceced8 |
549 | } |
2d711cc8 |
550 | return; |
96ceced8 |
551 | } |
552 | |
552e3d24 |
553 | ## Attributes |
554 | |
e16da3e6 |
555 | sub add_attribute { |
2e41896e |
556 | my $self = shift; |
557 | # either we have an attribute object already |
558 | # or we need to create one from the args provided |
559 | my $attribute = blessed($_[0]) ? $_[0] : $self->attribute_metaclass->new(@_); |
560 | # make sure it is derived from the correct type though |
561 | ($attribute->isa('Class::MOP::Attribute')) |
562 | || confess "Your attribute must be an instance of Class::MOP::Attribute (or a subclass)"; |
9ec169fe |
563 | $attribute->attach_to_class($self); |
2d711cc8 |
564 | $attribute->install_accessors(); |
291073fc |
565 | $self->get_attribute_map->{$attribute->name} = $attribute; |
e16da3e6 |
566 | } |
567 | |
568 | sub has_attribute { |
569 | my ($self, $attribute_name) = @_; |
570 | (defined $attribute_name && $attribute_name) |
571 | || confess "You must define an attribute name"; |
291073fc |
572 | exists $self->get_attribute_map->{$attribute_name} ? 1 : 0; |
e16da3e6 |
573 | } |
574 | |
575 | sub get_attribute { |
576 | my ($self, $attribute_name) = @_; |
577 | (defined $attribute_name && $attribute_name) |
578 | || confess "You must define an attribute name"; |
f7259199 |
579 | return $self->get_attribute_map->{$attribute_name} |
580 | if $self->has_attribute($attribute_name); |
22286063 |
581 | return; |
e16da3e6 |
582 | } |
583 | |
584 | sub remove_attribute { |
585 | my ($self, $attribute_name) = @_; |
586 | (defined $attribute_name && $attribute_name) |
587 | || confess "You must define an attribute name"; |
7b31baf4 |
588 | my $removed_attribute = $self->get_attribute_map->{$attribute_name}; |
22286063 |
589 | return unless defined $removed_attribute; |
590 | delete $self->get_attribute_map->{$attribute_name}; |
2d711cc8 |
591 | $removed_attribute->remove_accessors(); |
2d711cc8 |
592 | $removed_attribute->detach_from_class(); |
e16da3e6 |
593 | return $removed_attribute; |
594 | } |
595 | |
596 | sub get_attribute_list { |
597 | my $self = shift; |
f7259199 |
598 | keys %{$self->get_attribute_map}; |
e16da3e6 |
599 | } |
600 | |
601 | sub compute_all_applicable_attributes { |
602 | my $self = shift; |
603 | my @attrs; |
604 | # keep a record of what we have seen |
605 | # here, this will handle all the |
606 | # inheritence issues because we are |
607 | # using the &class_precedence_list |
608 | my (%seen_class, %seen_attr); |
609 | foreach my $class ($self->class_precedence_list()) { |
610 | next if $seen_class{$class}; |
611 | $seen_class{$class}++; |
612 | # fetch the meta-class ... |
f7259199 |
613 | my $meta = $self->initialize($class); |
e16da3e6 |
614 | foreach my $attr_name ($meta->get_attribute_list()) { |
615 | next if exists $seen_attr{$attr_name}; |
616 | $seen_attr{$attr_name}++; |
c9e77dbb |
617 | push @attrs => $meta->get_attribute($attr_name); |
e16da3e6 |
618 | } |
619 | } |
620 | return @attrs; |
621 | } |
2eb717d5 |
622 | |
058c1cf5 |
623 | sub find_attribute_by_name { |
624 | my ($self, $attr_name) = @_; |
625 | # keep a record of what we have seen |
626 | # here, this will handle all the |
627 | # inheritence issues because we are |
628 | # using the &class_precedence_list |
629 | my %seen_class; |
630 | foreach my $class ($self->class_precedence_list()) { |
631 | next if $seen_class{$class}; |
632 | $seen_class{$class}++; |
633 | # fetch the meta-class ... |
634 | my $meta = $self->initialize($class); |
635 | return $meta->get_attribute($attr_name) |
636 | if $meta->has_attribute($attr_name); |
637 | } |
638 | return; |
639 | } |
640 | |
857f87a7 |
641 | ## Class closing |
642 | |
643 | sub is_mutable { 1 } |
644 | sub is_immutable { 0 } |
645 | |
646 | sub make_immutable { |
c0cbf4d9 |
647 | return Class::MOP::Class::Immutable->make_metaclass_immutable(@_); |
857f87a7 |
648 | } |
649 | |
8b978dd5 |
650 | 1; |
651 | |
652 | __END__ |
653 | |
654 | =pod |
655 | |
656 | =head1 NAME |
657 | |
658 | Class::MOP::Class - Class Meta Object |
659 | |
660 | =head1 SYNOPSIS |
661 | |
8c936afc |
662 | # assuming that class Foo |
663 | # has been defined, you can |
664 | |
fe122940 |
665 | # use this for introspection ... |
666 | |
fe122940 |
667 | # add a method to Foo ... |
668 | Foo->meta->add_method('bar' => sub { ... }) |
669 | |
670 | # get a list of all the classes searched |
671 | # the method dispatcher in the correct order |
672 | Foo->meta->class_precedence_list() |
673 | |
674 | # remove a method from Foo |
675 | Foo->meta->remove_method('bar'); |
676 | |
677 | # or use this to actually create classes ... |
678 | |
679 | Class::MOP::Class->create('Bar' => '0.01' => ( |
680 | superclasses => [ 'Foo' ], |
681 | attributes => [ |
682 | Class::MOP:::Attribute->new('$bar'), |
683 | Class::MOP:::Attribute->new('$baz'), |
684 | ], |
685 | methods => { |
686 | calculate_bar => sub { ... }, |
687 | construct_baz => sub { ... } |
688 | } |
689 | )); |
690 | |
8b978dd5 |
691 | =head1 DESCRIPTION |
692 | |
fe122940 |
693 | This is the largest and currently most complex part of the Perl 5 |
694 | meta-object protocol. It controls the introspection and |
695 | manipulation of Perl 5 classes (and it can create them too). The |
696 | best way to understand what this module can do, is to read the |
697 | documentation for each of it's methods. |
698 | |
552e3d24 |
699 | =head1 METHODS |
700 | |
2eb717d5 |
701 | =head2 Self Introspection |
702 | |
703 | =over 4 |
704 | |
705 | =item B<meta> |
706 | |
fe122940 |
707 | This will return a B<Class::MOP::Class> instance which is related |
708 | to this class. Thereby allowing B<Class::MOP::Class> to actually |
709 | introspect itself. |
710 | |
711 | As with B<Class::MOP::Attribute>, B<Class::MOP> will actually |
712 | bootstrap this module by installing a number of attribute meta-objects |
713 | into it's metaclass. This will allow this class to reap all the benifits |
714 | of the MOP when subclassing it. |
2eb717d5 |
715 | |
716 | =back |
717 | |
552e3d24 |
718 | =head2 Class construction |
719 | |
a2e85e6c |
720 | These methods will handle creating B<Class::MOP::Class> objects, |
721 | which can be used to both create new classes, and analyze |
722 | pre-existing classes. |
552e3d24 |
723 | |
724 | This module will internally store references to all the instances |
725 | you create with these methods, so that they do not need to be |
726 | created any more than nessecary. Basically, they are singletons. |
727 | |
728 | =over 4 |
729 | |
730 | =item B<create ($package_name, ?$package_version, |
a2e85e6c |
731 | superclasses =E<gt> ?@superclasses, |
732 | methods =E<gt> ?%methods, |
733 | attributes =E<gt> ?%attributes)> |
552e3d24 |
734 | |
a2e85e6c |
735 | This returns a B<Class::MOP::Class> object, bringing the specified |
552e3d24 |
736 | C<$package_name> into existence and adding any of the |
737 | C<$package_version>, C<@superclasses>, C<%methods> and C<%attributes> |
738 | to it. |
739 | |
587aca23 |
740 | =item B<create_anon_class (superclasses =E<gt> ?@superclasses, |
741 | methods =E<gt> ?%methods, |
742 | attributes =E<gt> ?%attributes)> |
743 | |
744 | This will create an anonymous class, it works much like C<create> but |
745 | it does not need a C<$package_name>. Instead it will create a suitably |
746 | unique package name for you to stash things into. |
747 | |
66b3dded |
748 | =item B<initialize ($package_name, %options)> |
552e3d24 |
749 | |
a2e85e6c |
750 | This initializes and returns returns a B<Class::MOP::Class> object |
751 | for a given a C<$package_name>. |
752 | |
66b3dded |
753 | =item B<reinitialize ($package_name, %options)> |
754 | |
755 | This removes the old metaclass, and creates a new one in it's place. |
756 | Do B<not> use this unless you really know what you are doing, it could |
757 | very easily make a very large mess of your program. |
758 | |
651955fb |
759 | =item B<construct_class_instance (%options)> |
a2e85e6c |
760 | |
761 | This will construct an instance of B<Class::MOP::Class>, it is |
762 | here so that we can actually "tie the knot" for B<Class::MOP::Class> |
763 | to use C<construct_instance> once all the bootstrapping is done. This |
764 | method is used internally by C<initialize> and should never be called |
765 | from outside of that method really. |
552e3d24 |
766 | |
550d56db |
767 | =item B<check_metaclass_compatability> |
768 | |
769 | This method is called as the very last thing in the |
770 | C<construct_class_instance> method. This will check that the |
771 | metaclass you are creating is compatible with the metaclasses of all |
772 | your ancestors. For more inforamtion about metaclass compatibility |
773 | see the C<About Metaclass compatibility> section in L<Class::MOP>. |
774 | |
552e3d24 |
775 | =back |
776 | |
c9e77dbb |
777 | =head2 Object instance construction and cloning |
a2e85e6c |
778 | |
c9e77dbb |
779 | These methods are B<entirely optional>, it is up to you whether you want |
780 | to use them or not. |
552e3d24 |
781 | |
782 | =over 4 |
783 | |
2bab2be6 |
784 | =item B<instance_metaclass> |
785 | |
2d711cc8 |
786 | =item B<get_meta_instance> |
787 | |
5f3c057a |
788 | =item B<new_object (%params)> |
789 | |
790 | This is a convience method for creating a new object of the class, and |
791 | blessing it into the appropriate package as well. Ideally your class |
792 | would call a C<new> this method like so: |
793 | |
794 | sub MyClass::new { |
795 | my ($class, %param) = @_; |
796 | $class->meta->new_object(%params); |
797 | } |
798 | |
799 | Of course the ideal place for this would actually be in C<UNIVERSAL::> |
800 | but that is considered bad style, so we do not do that. |
801 | |
cbd9f942 |
802 | =item B<construct_instance (%params)> |
552e3d24 |
803 | |
c9e77dbb |
804 | This method is used to construct an instace structure suitable for |
805 | C<bless>-ing into your package of choice. It works in conjunction |
806 | with the Attribute protocol to collect all applicable attributes. |
807 | |
cbd9f942 |
808 | This will construct and instance using a HASH ref as storage |
552e3d24 |
809 | (currently only HASH references are supported). This will collect all |
a2e85e6c |
810 | the applicable attributes and layout out the fields in the HASH ref, |
811 | it will then initialize them using either use the corresponding key |
812 | in C<%params> or any default value or initializer found in the |
813 | attribute meta-object. |
727919c5 |
814 | |
5f3c057a |
815 | =item B<clone_object ($instance, %params)> |
816 | |
817 | This is a convience method for cloning an object instance, then |
19d4b5b8 |
818 | blessing it into the appropriate package. This method will call |
819 | C<clone_instance>, which performs a shallow copy of the object, |
820 | see that methods documentation for more details. Ideally your |
821 | class would call a C<clone> this method like so: |
5f3c057a |
822 | |
823 | sub MyClass::clone { |
824 | my ($self, %param) = @_; |
825 | $self->meta->clone_object($self, %params); |
826 | } |
827 | |
828 | Of course the ideal place for this would actually be in C<UNIVERSAL::> |
829 | but that is considered bad style, so we do not do that. |
830 | |
c9e77dbb |
831 | =item B<clone_instance($instance, %params)> |
832 | |
833 | This method is a compliment of C<construct_instance> (which means if |
19d4b5b8 |
834 | you override C<construct_instance>, you need to override this one too), |
835 | and clones the instance shallowly. |
a27ae83f |
836 | |
837 | The cloned structure returned is (like with C<construct_instance>) an |
838 | unC<bless>ed HASH reference, it is your responsibility to then bless |
839 | this cloned structure into the right class (which C<clone_object> will |
840 | do for you). |
c9e77dbb |
841 | |
19d4b5b8 |
842 | As of 0.11, this method will clone the C<$instance> structure shallowly, |
843 | as opposed to the deep cloning implemented in prior versions. After much |
844 | thought, research and discussion, I have decided that anything but basic |
845 | shallow cloning is outside the scope of the meta-object protocol. I |
846 | think Yuval "nothingmuch" Kogman put it best when he said that cloning |
847 | is too I<context-specific> to be part of the MOP. |
848 | |
552e3d24 |
849 | =back |
850 | |
851 | =head2 Informational |
852 | |
b9d9fc0b |
853 | These are a few predicate methods for asking information about the class. |
552e3d24 |
854 | |
b9d9fc0b |
855 | =over 4 |
552e3d24 |
856 | |
b9d9fc0b |
857 | =item B<is_anon_class> |
552e3d24 |
858 | |
b9d9fc0b |
859 | =item B<is_mutable> |
552e3d24 |
860 | |
b9d9fc0b |
861 | =item B<is_immutable> |
552e3d24 |
862 | |
863 | =back |
864 | |
865 | =head2 Inheritance Relationships |
866 | |
867 | =over 4 |
868 | |
869 | =item B<superclasses (?@superclasses)> |
870 | |
871 | This is a read-write attribute which represents the superclass |
a2e85e6c |
872 | relationships of the class the B<Class::MOP::Class> instance is |
873 | associated with. Basically, it can get and set the C<@ISA> for you. |
552e3d24 |
874 | |
343203ee |
875 | B<NOTE:> |
876 | Perl will occasionally perform some C<@ISA> and method caching, if |
877 | you decide to change your superclass relationship at runtime (which |
878 | is quite insane and very much not recommened), then you should be |
879 | aware of this and the fact that this module does not make any |
880 | attempt to address this issue. |
881 | |
552e3d24 |
882 | =item B<class_precedence_list> |
883 | |
a2e85e6c |
884 | This computes the a list of all the class's ancestors in the same order |
885 | in which method dispatch will be done. This is similair to |
886 | what B<Class::ISA::super_path> does, but we don't remove duplicate names. |
552e3d24 |
887 | |
888 | =back |
889 | |
890 | =head2 Methods |
891 | |
892 | =over 4 |
893 | |
2e41896e |
894 | =item B<method_metaclass> |
895 | |
552e3d24 |
896 | =item B<add_method ($method_name, $method)> |
897 | |
898 | This will take a C<$method_name> and CODE reference to that |
a2e85e6c |
899 | C<$method> and install it into the class's package. |
552e3d24 |
900 | |
a2e85e6c |
901 | B<NOTE>: |
902 | This does absolutely nothing special to C<$method> |
552e3d24 |
903 | other than use B<Sub::Name> to make sure it is tagged with the |
904 | correct name, and therefore show up correctly in stack traces and |
905 | such. |
906 | |
663f8198 |
907 | =item B<alias_method ($method_name, $method)> |
908 | |
909 | This will take a C<$method_name> and CODE reference to that |
910 | C<$method> and alias the method into the class's package. |
911 | |
912 | B<NOTE>: |
913 | Unlike C<add_method>, this will B<not> try to name the |
914 | C<$method> using B<Sub::Name>, it only aliases the method in |
915 | the class's package. |
916 | |
552e3d24 |
917 | =item B<has_method ($method_name)> |
918 | |
a2e85e6c |
919 | This just provides a simple way to check if the class implements |
552e3d24 |
920 | a specific C<$method_name>. It will I<not> however, attempt to check |
a2e85e6c |
921 | if the class inherits the method (use C<UNIVERSAL::can> for that). |
552e3d24 |
922 | |
923 | This will correctly handle functions defined outside of the package |
924 | that use a fully qualified name (C<sub Package::name { ... }>). |
925 | |
926 | This will correctly handle functions renamed with B<Sub::Name> and |
927 | installed using the symbol tables. However, if you are naming the |
928 | subroutine outside of the package scope, you must use the fully |
929 | qualified name, including the package name, for C<has_method> to |
930 | correctly identify it. |
931 | |
932 | This will attempt to correctly ignore functions imported from other |
933 | packages using B<Exporter>. It breaks down if the function imported |
934 | is an C<__ANON__> sub (such as with C<use constant>), which very well |
935 | may be a valid method being applied to the class. |
936 | |
937 | In short, this method cannot always be trusted to determine if the |
938 | C<$method_name> is actually a method. However, it will DWIM about |
a2e85e6c |
939 | 90% of the time, so it's a small trade off I think. |
552e3d24 |
940 | |
941 | =item B<get_method ($method_name)> |
942 | |
943 | This will return a CODE reference of the specified C<$method_name>, |
944 | or return undef if that method does not exist. |
945 | |
16e960bd |
946 | =item B<find_method_by_name ($method_name> |
947 | |
948 | This will return a CODE reference of the specified C<$method_name>, |
949 | or return undef if that method does not exist. |
950 | |
951 | Unlike C<get_method> this will also look in the superclasses. |
952 | |
552e3d24 |
953 | =item B<remove_method ($method_name)> |
954 | |
a2e85e6c |
955 | This will attempt to remove a given C<$method_name> from the class. |
552e3d24 |
956 | It will return the CODE reference that it has removed, and will |
957 | attempt to use B<Sub::Name> to clear the methods associated name. |
958 | |
959 | =item B<get_method_list> |
960 | |
961 | This will return a list of method names for all I<locally> defined |
962 | methods. It does B<not> provide a list of all applicable methods, |
963 | including any inherited ones. If you want a list of all applicable |
964 | methods, use the C<compute_all_applicable_methods> method. |
965 | |
966 | =item B<compute_all_applicable_methods> |
967 | |
a2e85e6c |
968 | This will return a list of all the methods names this class will |
969 | respond to, taking into account inheritance. The list will be a list of |
552e3d24 |
970 | HASH references, each one containing the following information; method |
971 | name, the name of the class in which the method lives and a CODE |
972 | reference for the actual method. |
973 | |
974 | =item B<find_all_methods_by_name ($method_name)> |
975 | |
976 | This will traverse the inheritence hierarchy and locate all methods |
977 | with a given C<$method_name>. Similar to |
978 | C<compute_all_applicable_methods> it returns a list of HASH references |
979 | with the following information; method name (which will always be the |
980 | same as C<$method_name>), the name of the class in which the method |
981 | lives and a CODE reference for the actual method. |
982 | |
983 | The list of methods produced is a distinct list, meaning there are no |
984 | duplicates in it. This is especially useful for things like object |
985 | initialization and destruction where you only want the method called |
986 | once, and in the correct order. |
987 | |
96ceced8 |
988 | =item B<find_next_method_by_name ($method_name)> |
989 | |
990 | This will return the first method to match a given C<$method_name> in |
991 | the superclasses, this is basically equivalent to calling |
992 | C<SUPER::$method_name>, but it can be dispatched at runtime. |
993 | |
552e3d24 |
994 | =back |
995 | |
a4258ffd |
996 | =head2 Method Modifiers |
997 | |
96ceced8 |
998 | Method modifiers are a concept borrowed from CLOS, in which a method |
999 | can be wrapped with I<before>, I<after> and I<around> method modifiers |
1000 | that will be called everytime the method is called. |
1001 | |
1002 | =head3 How method modifiers work? |
1003 | |
1004 | Method modifiers work by wrapping the original method and then replacing |
1005 | it in the classes symbol table. The wrappers will handle calling all the |
1006 | modifiers in the appropariate orders and preserving the calling context |
1007 | for the original method. |
1008 | |
1009 | Each method modifier serves a particular purpose, which may not be |
1010 | obvious to users of other method wrapping modules. To start with, the |
1011 | return values of I<before> and I<after> modifiers are ignored. This is |
1012 | because thier purpose is B<not> to filter the input and output of the |
1013 | primary method (this is done with an I<around> modifier). This may seem |
1014 | like an odd restriction to some, but doing this allows for simple code |
1015 | to be added at the begining or end of a method call without jeapordizing |
1016 | the normal functioning of the primary method or placing any extra |
1017 | responsibility on the code of the modifier. Of course if you have more |
1018 | complex needs, then use the I<around> modifier, which uses a variation |
1019 | of continutation passing style to allow for a high degree of flexibility. |
1020 | |
1021 | Before and around modifiers are called in last-defined-first-called order, |
1022 | while after modifiers are called in first-defined-first-called order. So |
1023 | the call tree might looks something like this: |
1024 | |
1025 | before 2 |
1026 | before 1 |
1027 | around 2 |
1028 | around 1 |
1029 | primary |
1030 | after 1 |
1031 | after 2 |
1032 | |
1033 | To see examples of using method modifiers, see the following examples |
1034 | included in the distribution; F<InstanceCountingClass>, F<Perl6Attribute>, |
1035 | F<AttributesWithHistory> and F<C3MethodDispatchOrder>. There is also a |
1036 | classic CLOS usage example in the test F<017_add_method_modifier.t>. |
1037 | |
1038 | =head3 What is the performance impact? |
1039 | |
1040 | Of course there is a performance cost associated with method modifiers, |
1041 | but we have made every effort to make that cost be directly proportional |
1042 | to the amount of modifier features you utilize. |
1043 | |
1044 | The wrapping method does it's best to B<only> do as much work as it |
1045 | absolutely needs to. In order to do this we have moved some of the |
1046 | performance costs to set-up time, where they are easier to amortize. |
1047 | |
1048 | All this said, my benchmarks have indicated the following: |
1049 | |
1050 | simple wrapper with no modifiers 100% slower |
1051 | simple wrapper with simple before modifier 400% slower |
1052 | simple wrapper with simple after modifier 450% slower |
1053 | simple wrapper with simple around modifier 500-550% slower |
1054 | simple wrapper with all 3 modifiers 1100% slower |
1055 | |
1056 | These numbers may seem daunting, but you must remember, every feature |
1057 | comes with some cost. To put things in perspective, just doing a simple |
1058 | C<AUTOLOAD> which does nothing but extract the name of the method called |
1059 | and return it costs about 400% over a normal method call. |
1060 | |
a4258ffd |
1061 | =over 4 |
1062 | |
1063 | =item B<add_before_method_modifier ($method_name, $code)> |
1064 | |
96ceced8 |
1065 | This will wrap the method at C<$method_name> and the supplied C<$code> |
1066 | will be passed the C<@_> arguments, and called before the original |
1067 | method is called. As specified above, the return value of the I<before> |
1068 | method modifiers is ignored, and it's ability to modify C<@_> is |
1069 | fairly limited. If you need to do either of these things, use an |
1070 | C<around> method modifier. |
1071 | |
a4258ffd |
1072 | =item B<add_after_method_modifier ($method_name, $code)> |
1073 | |
96ceced8 |
1074 | This will wrap the method at C<$method_name> so that the original |
1075 | method will be called, it's return values stashed, and then the |
1076 | supplied C<$code> will be passed the C<@_> arguments, and called. |
1077 | As specified above, the return value of the I<after> method |
1078 | modifiers is ignored, and it cannot modify the return values of |
1079 | the original method. If you need to do either of these things, use an |
1080 | C<around> method modifier. |
1081 | |
a4258ffd |
1082 | =item B<add_around_method_modifier ($method_name, $code)> |
1083 | |
96ceced8 |
1084 | This will wrap the method at C<$method_name> so that C<$code> |
1085 | will be called and passed the original method as an extra argument |
1086 | at the begining of the C<@_> argument list. This is a variation of |
1087 | continuation passing style, where the function prepended to C<@_> |
1088 | can be considered a continuation. It is up to C<$code> if it calls |
1089 | the original method or not, there is no restriction on what the |
1090 | C<$code> can or cannot do. |
1091 | |
a4258ffd |
1092 | =back |
1093 | |
552e3d24 |
1094 | =head2 Attributes |
1095 | |
1096 | It should be noted that since there is no one consistent way to define |
1097 | the attributes of a class in Perl 5. These methods can only work with |
1098 | the information given, and can not easily discover information on |
a2e85e6c |
1099 | their own. See L<Class::MOP::Attribute> for more details. |
552e3d24 |
1100 | |
1101 | =over 4 |
1102 | |
2e41896e |
1103 | =item B<attribute_metaclass> |
1104 | |
7b31baf4 |
1105 | =item B<get_attribute_map> |
1106 | |
552e3d24 |
1107 | =item B<add_attribute ($attribute_name, $attribute_meta_object)> |
1108 | |
a2e85e6c |
1109 | This stores a C<$attribute_meta_object> in the B<Class::MOP::Class> |
1110 | instance associated with the given class, and associates it with |
1111 | the C<$attribute_name>. Unlike methods, attributes within the MOP |
1112 | are stored as meta-information only. They will be used later to |
1113 | construct instances from (see C<construct_instance> above). |
552e3d24 |
1114 | More details about the attribute meta-objects can be found in the |
a2e85e6c |
1115 | L<Class::MOP::Attribute> or the L<Class::MOP/The Attribute protocol> |
1116 | section. |
1117 | |
1118 | It should be noted that any accessor, reader/writer or predicate |
1119 | methods which the C<$attribute_meta_object> has will be installed |
1120 | into the class at this time. |
552e3d24 |
1121 | |
1122 | =item B<has_attribute ($attribute_name)> |
1123 | |
a2e85e6c |
1124 | Checks to see if this class has an attribute by the name of |
552e3d24 |
1125 | C<$attribute_name> and returns a boolean. |
1126 | |
1127 | =item B<get_attribute ($attribute_name)> |
1128 | |
1129 | Returns the attribute meta-object associated with C<$attribute_name>, |
1130 | if none is found, it will return undef. |
1131 | |
1132 | =item B<remove_attribute ($attribute_name)> |
1133 | |
1134 | This will remove the attribute meta-object stored at |
1135 | C<$attribute_name>, then return the removed attribute meta-object. |
1136 | |
a2e85e6c |
1137 | B<NOTE:> |
1138 | Removing an attribute will only affect future instances of |
552e3d24 |
1139 | the class, it will not make any attempt to remove the attribute from |
1140 | any existing instances of the class. |
1141 | |
a2e85e6c |
1142 | It should be noted that any accessor, reader/writer or predicate |
1143 | methods which the attribute meta-object stored at C<$attribute_name> |
1144 | has will be removed from the class at this time. This B<will> make |
1145 | these attributes somewhat inaccessable in previously created |
1146 | instances. But if you are crazy enough to do this at runtime, then |
1147 | you are crazy enough to deal with something like this :). |
1148 | |
552e3d24 |
1149 | =item B<get_attribute_list> |
1150 | |
1151 | This returns a list of attribute names which are defined in the local |
1152 | class. If you want a list of all applicable attributes for a class, |
1153 | use the C<compute_all_applicable_attributes> method. |
1154 | |
1155 | =item B<compute_all_applicable_attributes> |
1156 | |
c9e77dbb |
1157 | This will traverse the inheritance heirachy and return a list of all |
1158 | the applicable attributes for this class. It does not construct a |
1159 | HASH reference like C<compute_all_applicable_methods> because all |
1160 | that same information is discoverable through the attribute |
1161 | meta-object itself. |
552e3d24 |
1162 | |
058c1cf5 |
1163 | =item B<find_attribute_by_name ($attr_name)> |
1164 | |
1165 | This method will traverse the inheritance heirachy and find the |
1166 | first attribute whose name matches C<$attr_name>, then return it. |
1167 | It will return undef if nothing is found. |
1168 | |
552e3d24 |
1169 | =back |
1170 | |
857f87a7 |
1171 | =head2 Class closing |
1172 | |
1173 | =over 4 |
1174 | |
857f87a7 |
1175 | =item B<make_immutable> |
1176 | |
1177 | =back |
1178 | |
1a09d9cc |
1179 | =head1 AUTHORS |
8b978dd5 |
1180 | |
a2e85e6c |
1181 | Stevan Little E<lt>stevan@iinteractive.comE<gt> |
8b978dd5 |
1182 | |
1a09d9cc |
1183 | Yuval Kogman E<lt>nothingmuch@woobling.comE<gt> |
1184 | |
8b978dd5 |
1185 | =head1 COPYRIGHT AND LICENSE |
1186 | |
1187 | Copyright 2006 by Infinity Interactive, Inc. |
1188 | |
1189 | L<http://www.iinteractive.com> |
1190 | |
1191 | This library is free software; you can redistribute it and/or modify |
1192 | it under the same terms as Perl itself. |
1193 | |
798baea5 |
1194 | =cut |