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'; |
96ceced8 |
10 | use B 'svref_2object'; |
8b978dd5 |
11 | |
2bab2be6 |
12 | our $VERSION = '0.14'; |
8b978dd5 |
13 | |
839ea973 |
14 | use Class::MOP::Instance; |
15 | |
aa448b16 |
16 | # Self-introspection |
2eb717d5 |
17 | |
aa448b16 |
18 | sub meta { Class::MOP::Class->initialize(blessed($_[0]) || $_[0]) } |
2eb717d5 |
19 | |
8b978dd5 |
20 | # Creation |
21 | |
f7259199 |
22 | { |
bfe4d0fc |
23 | # Metaclasses are singletons, so we cache them here. |
24 | # there is no need to worry about destruction though |
25 | # because they should die only when the program dies. |
26 | # After all, do package definitions even get reaped? |
587aca23 |
27 | my %METAS; |
28 | |
29 | # means of accessing all the metaclasses that have |
30 | # been initialized thus far (for mugwumps obj browser) |
31 | sub get_all_metaclasses { %METAS } |
32 | sub get_all_metaclass_instances { values %METAS } |
33 | sub get_all_metaclass_names { keys %METAS } |
651955fb |
34 | |
bfe4d0fc |
35 | sub initialize { |
351bd7d4 |
36 | my $class = shift; |
37 | my $package_name = shift; |
22286063 |
38 | (defined $package_name && $package_name && !blessed($package_name)) |
39 | || confess "You must pass a package name and it cannot be blessed"; |
651955fb |
40 | $class->construct_class_instance(':package' => $package_name, @_); |
727919c5 |
41 | } |
42 | |
43 | # NOTE: (meta-circularity) |
44 | # this is a special form of &construct_instance |
45 | # (see below), which is used to construct class |
1a7ebbb3 |
46 | # meta-object instances for any Class::MOP::* |
47 | # class. All other classes will use the more |
48 | # normal &construct_instance. |
727919c5 |
49 | sub construct_class_instance { |
351bd7d4 |
50 | my $class = shift; |
651955fb |
51 | my %options = @_; |
52 | my $package_name = $options{':package'}; |
727919c5 |
53 | (defined $package_name && $package_name) |
651955fb |
54 | || confess "You must pass a package name"; |
2d711cc8 |
55 | # NOTE: |
56 | # return the metaclass if we have it cached, |
57 | # and it is still defined (it has not been |
58 | # reaped by DESTROY yet, which can happen |
59 | # annoyingly enough during global destruction) |
2f6d5412 |
60 | return $METAS{$package_name} |
2d711cc8 |
61 | if exists $METAS{$package_name} && defined $METAS{$package_name}; |
1a7ebbb3 |
62 | $class = blessed($class) || $class; |
550d56db |
63 | # now create the metaclass |
64 | my $meta; |
1a7ebbb3 |
65 | if ($class =~ /^Class::MOP::/) { |
550d56db |
66 | $meta = bless { |
351bd7d4 |
67 | '$:package' => $package_name, |
68 | '%:attributes' => {}, |
550d56db |
69 | '$:attribute_metaclass' => $options{':attribute_metaclass'} || 'Class::MOP::Attribute', |
2bab2be6 |
70 | '$:method_metaclass' => $options{':method_metaclass'} || 'Class::MOP::Method', |
71 | '$:instance_metaclass' => $options{':instance_metaclass'} || 'Class::MOP::Instance', |
1a7ebbb3 |
72 | } => $class; |
73 | } |
74 | else { |
5f3c057a |
75 | # NOTE: |
76 | # it is safe to use meta here because |
77 | # class will always be a subclass of |
78 | # Class::MOP::Class, which defines meta |
550d56db |
79 | $meta = bless $class->meta->construct_instance(%options) => $class |
1a7ebbb3 |
80 | } |
550d56db |
81 | # and check the metaclass compatibility |
82 | $meta->check_metaclass_compatability(); |
83 | $METAS{$package_name} = $meta; |
84 | } |
85 | |
86 | sub check_metaclass_compatability { |
87 | my $self = shift; |
88 | |
89 | # this is always okay ... |
90 | return if blessed($self) eq 'Class::MOP::Class'; |
91 | |
92 | my @class_list = $self->class_precedence_list; |
93 | shift @class_list; # shift off $self->name |
94 | |
95 | foreach my $class_name (@class_list) { |
96ceced8 |
96 | my $meta = $METAS{$class_name} || next; |
550d56db |
97 | ($self->isa(blessed($meta))) |
98 | || confess $self->name . "->meta => (" . (blessed($self)) . ")" . |
99 | " is not compatible with the " . |
100 | $class_name . "->meta => (" . (blessed($meta)) . ")"; |
f7259199 |
101 | # NOTE: |
102 | # we also need to check that instance metaclasses |
103 | # are compatabile in the same the class. |
104 | ($self->instance_metaclass->isa($meta->instance_metaclass)) |
105 | || confess $self->name . "->meta => (" . ($self->instance_metaclass) . ")" . |
106 | " is not compatible with the " . |
107 | $class_name . "->meta => (" . ($meta->instance_metaclass) . ")"; |
550d56db |
108 | } |
bfe4d0fc |
109 | } |
f7259199 |
110 | } |
8b978dd5 |
111 | |
112 | sub create { |
113 | my ($class, $package_name, $package_version, %options) = @_; |
bfe4d0fc |
114 | (defined $package_name && $package_name) |
8b978dd5 |
115 | || confess "You must pass a package name"; |
116 | my $code = "package $package_name;"; |
117 | $code .= "\$$package_name\:\:VERSION = '$package_version';" |
118 | if defined $package_version; |
119 | eval $code; |
120 | confess "creation of $package_name failed : $@" if $@; |
bfe4d0fc |
121 | my $meta = $class->initialize($package_name); |
aa448b16 |
122 | |
123 | $meta->add_method('meta' => sub { |
124 | Class::MOP::Class->initialize(blessed($_[0]) || $_[0]); |
125 | }); |
126 | |
8b978dd5 |
127 | $meta->superclasses(@{$options{superclasses}}) |
128 | if exists $options{superclasses}; |
2eb717d5 |
129 | # NOTE: |
130 | # process attributes first, so that they can |
131 | # install accessors, but locally defined methods |
132 | # can then overwrite them. It is maybe a little odd, but |
133 | # I think this should be the order of things. |
134 | if (exists $options{attributes}) { |
cbd9f942 |
135 | foreach my $attr (@{$options{attributes}}) { |
136 | $meta->add_attribute($attr); |
2eb717d5 |
137 | } |
138 | } |
bfe4d0fc |
139 | if (exists $options{methods}) { |
140 | foreach my $method_name (keys %{$options{methods}}) { |
141 | $meta->add_method($method_name, $options{methods}->{$method_name}); |
142 | } |
2eb717d5 |
143 | } |
8b978dd5 |
144 | return $meta; |
145 | } |
146 | |
c3e7c446 |
147 | { |
4d154c08 |
148 | # NOTE: |
149 | # this should be sufficient, if you have a |
150 | # use case where it is not, write a test and |
151 | # I will change it. |
c3e7c446 |
152 | my $ANON_CLASS_SERIAL = 0; |
4d154c08 |
153 | |
c3e7c446 |
154 | sub create_anon_class { |
155 | my ($class, %options) = @_; |
156 | my $package_name = 'Class::MOP::Class::__ANON__::SERIAL::' . ++$ANON_CLASS_SERIAL; |
157 | return $class->create($package_name, '0.00', %options); |
158 | } |
587aca23 |
159 | } |
160 | |
7b31baf4 |
161 | ## Attribute readers |
162 | |
163 | # NOTE: |
164 | # all these attribute readers will be bootstrapped |
165 | # away in the Class::MOP bootstrap section |
166 | |
167 | sub name { $_[0]->{'$:package'} } |
168 | sub get_attribute_map { $_[0]->{'%:attributes'} } |
169 | sub attribute_metaclass { $_[0]->{'$:attribute_metaclass'} } |
170 | sub method_metaclass { $_[0]->{'$:method_metaclass'} } |
2bab2be6 |
171 | sub instance_metaclass { $_[0]->{'$:instance_metaclass'} } |
7b31baf4 |
172 | |
c9e77dbb |
173 | # Instance Construction & Cloning |
174 | |
5f3c057a |
175 | sub new_object { |
176 | my $class = shift; |
651955fb |
177 | # NOTE: |
178 | # we need to protect the integrity of the |
179 | # Class::MOP::Class singletons here, so we |
180 | # delegate this to &construct_class_instance |
181 | # which will deal with the singletons |
182 | return $class->construct_class_instance(@_) |
183 | if $class->name->isa('Class::MOP::Class'); |
24869f62 |
184 | return $class->construct_instance(@_); |
5f3c057a |
185 | } |
e16da3e6 |
186 | |
187 | sub construct_instance { |
cbd9f942 |
188 | my ($class, %params) = @_; |
0e76a376 |
189 | my $meta_instance = $class->get_meta_instance(); |
190 | my $instance = $meta_instance->create_instance(); |
c9e77dbb |
191 | foreach my $attr ($class->compute_all_applicable_attributes()) { |
f892c0f0 |
192 | $attr->initialize_instance_slot($meta_instance, $instance, \%params); |
cbd9f942 |
193 | } |
2d711cc8 |
194 | return $instance; |
195 | } |
196 | |
197 | sub get_meta_instance { |
198 | my $class = shift; |
052c2a1a |
199 | return $class->instance_metaclass->new( |
200 | $class, |
201 | $class->compute_all_applicable_attributes() |
202 | ); |
e16da3e6 |
203 | } |
204 | |
5f3c057a |
205 | sub clone_object { |
206 | my $class = shift; |
7b31baf4 |
207 | my $instance = shift; |
651955fb |
208 | (blessed($instance) && $instance->isa($class->name)) |
209 | || confess "You must pass an instance ($instance) of the metaclass (" . $class->name . ")"; |
210 | # NOTE: |
211 | # we need to protect the integrity of the |
212 | # Class::MOP::Class singletons here, they |
a740253a |
213 | # should not be cloned. |
651955fb |
214 | return $instance if $instance->isa('Class::MOP::Class'); |
f7259199 |
215 | $class->clone_instance($instance, @_); |
5f3c057a |
216 | } |
217 | |
c9e77dbb |
218 | sub clone_instance { |
651955fb |
219 | my ($class, $instance, %params) = @_; |
220 | (blessed($instance)) |
c9e77dbb |
221 | || confess "You can only clone instances, \$self is not a blessed instance"; |
f7259199 |
222 | my $meta_instance = $class->get_meta_instance(); |
223 | my $clone = $meta_instance->clone_instance($instance); |
224 | foreach my $key (%params) { |
225 | next unless $meta_instance->is_valid_slot($key); |
226 | $meta_instance->set_slot_value($clone, $key, $params{$key}); |
227 | } |
c9e77dbb |
228 | return $clone; |
229 | } |
230 | |
8b978dd5 |
231 | # Informational |
232 | |
7b31baf4 |
233 | # &name should be here too, but it is above |
234 | # because it gets bootstrapped away |
8b978dd5 |
235 | |
236 | sub version { |
237 | my $self = shift; |
96ceced8 |
238 | ${$self->get_package_variable('$VERSION')}; |
8b978dd5 |
239 | } |
240 | |
241 | # Inheritance |
242 | |
243 | sub superclasses { |
244 | my $self = shift; |
e7f732e4 |
245 | no strict 'refs'; |
8b978dd5 |
246 | if (@_) { |
247 | my @supers = @_; |
e7f732e4 |
248 | @{$self->name . '::ISA'} = @supers; |
8b978dd5 |
249 | } |
e7f732e4 |
250 | @{$self->name . '::ISA'}; |
8b978dd5 |
251 | } |
252 | |
253 | sub class_precedence_list { |
254 | my $self = shift; |
bfe4d0fc |
255 | # NOTE: |
256 | # We need to check for ciruclar inheirtance here. |
257 | # This will do nothing if all is well, and blow |
258 | # up otherwise. Yes, it's an ugly hack, better |
259 | # suggestions are welcome. |
93b4e576 |
260 | { ($self->name || return)->isa('This is a test for circular inheritance') } |
8c936afc |
261 | # ... and now back to our regularly scheduled program |
8b978dd5 |
262 | ( |
263 | $self->name, |
264 | map { |
f7259199 |
265 | $self->initialize($_)->class_precedence_list() |
8b978dd5 |
266 | } $self->superclasses() |
267 | ); |
268 | } |
269 | |
0882828e |
270 | ## Methods |
271 | |
272 | sub add_method { |
273 | my ($self, $method_name, $method) = @_; |
274 | (defined $method_name && $method_name) |
275 | || confess "You must define a method name"; |
a5eca695 |
276 | # use reftype here to allow for blessed subs ... |
ee5e71d4 |
277 | ('CODE' eq (reftype($method) || '')) |
0882828e |
278 | || confess "Your code block must be a CODE reference"; |
279 | my $full_method_name = ($self->name . '::' . $method_name); |
de19f115 |
280 | |
2d711cc8 |
281 | $method = $self->method_metaclass->wrap($method) unless blessed($method); |
282 | |
0882828e |
283 | no strict 'refs'; |
c9b8b7f9 |
284 | no warnings 'redefine'; |
22286063 |
285 | *{$full_method_name} = subname $full_method_name => $method; |
0882828e |
286 | } |
287 | |
a4258ffd |
288 | { |
2d711cc8 |
289 | my $fetch_and_prepare_method = sub { |
290 | my ($self, $method_name) = @_; |
291 | # fetch it locally |
292 | my $method = $self->get_method($method_name); |
293 | # if we dont have local ... |
294 | unless ($method) { |
295 | # make sure this method even exists ... |
296 | ($self->find_next_method_by_name($method_name)) |
297 | || confess "The method '$method_name' is not found in the inherience hierarchy for this class"; |
298 | # if so, then create a local which just |
299 | # calls the next applicable method ... |
300 | $self->add_method($method_name => sub { |
301 | $self->find_next_method_by_name($method_name)->(@_); |
302 | }); |
303 | $method = $self->get_method($method_name); |
304 | } |
305 | |
306 | # now make sure we wrap it properly |
307 | # (if it isnt already) |
308 | unless ($method->isa('Class::MOP::Method::Wrapped')) { |
309 | $method = Class::MOP::Method::Wrapped->wrap($method); |
310 | $self->add_method($method_name => $method); |
311 | } |
312 | return $method; |
313 | }; |
314 | |
315 | sub add_before_method_modifier { |
316 | my ($self, $method_name, $method_modifier) = @_; |
317 | (defined $method_name && $method_name) |
318 | || confess "You must pass in a method name"; |
319 | my $method = $fetch_and_prepare_method->($self, $method_name); |
320 | $method->add_before_modifier(subname ':before' => $method_modifier); |
321 | } |
322 | |
323 | sub add_after_method_modifier { |
324 | my ($self, $method_name, $method_modifier) = @_; |
325 | (defined $method_name && $method_name) |
326 | || confess "You must pass in a method name"; |
327 | my $method = $fetch_and_prepare_method->($self, $method_name); |
328 | $method->add_after_modifier(subname ':after' => $method_modifier); |
329 | } |
330 | |
331 | sub add_around_method_modifier { |
332 | my ($self, $method_name, $method_modifier) = @_; |
333 | (defined $method_name && $method_name) |
334 | || confess "You must pass in a method name"; |
335 | my $method = $fetch_and_prepare_method->($self, $method_name); |
336 | $method->add_around_modifier(subname ':around' => $method_modifier); |
337 | } |
a4258ffd |
338 | |
8c936afc |
339 | # NOTE: |
340 | # the methods above used to be named like this: |
341 | # ${pkg}::${method}:(before|after|around) |
342 | # but this proved problematic when using one modifier |
343 | # to wrap multiple methods (something which is likely |
344 | # to happen pretty regularly IMO). So instead of naming |
345 | # it like this, I have chosen to just name them purely |
346 | # with their modifier names, like so: |
347 | # :(before|after|around) |
348 | # The fact is that in a stack trace, it will be fairly |
349 | # evident from the context what method they are attached |
350 | # to, and so don't need the fully qualified name. |
ee5e71d4 |
351 | } |
352 | |
663f8198 |
353 | sub alias_method { |
354 | my ($self, $method_name, $method) = @_; |
355 | (defined $method_name && $method_name) |
356 | || confess "You must define a method name"; |
357 | # use reftype here to allow for blessed subs ... |
ee5e71d4 |
358 | ('CODE' eq (reftype($method) || '')) |
663f8198 |
359 | || confess "Your code block must be a CODE reference"; |
de19f115 |
360 | my $full_method_name = ($self->name . '::' . $method_name); |
361 | |
2d711cc8 |
362 | $method = $self->method_metaclass->wrap($method) unless blessed($method); |
663f8198 |
363 | |
364 | no strict 'refs'; |
365 | no warnings 'redefine'; |
366 | *{$full_method_name} = $method; |
367 | } |
368 | |
de19f115 |
369 | sub has_method { |
370 | my ($self, $method_name) = @_; |
371 | (defined $method_name && $method_name) |
372 | || confess "You must define a method name"; |
bfe4d0fc |
373 | |
de19f115 |
374 | my $sub_name = ($self->name . '::' . $method_name); |
0882828e |
375 | |
de19f115 |
376 | no strict 'refs'; |
377 | return 0 if !defined(&{$sub_name}); |
2d711cc8 |
378 | my $method = \&{$sub_name}; |
96ceced8 |
379 | return 0 if (svref_2object($method)->GV->STASH->NAME || '') ne $self->name && |
2d711cc8 |
380 | (svref_2object($method)->GV->NAME || '') ne '__ANON__'; |
381 | |
382 | # at this point we are relatively sure |
383 | # it is our method, so we bless/wrap it |
384 | $self->method_metaclass->wrap($method) unless blessed($method); |
de19f115 |
385 | return 1; |
0882828e |
386 | } |
387 | |
388 | sub get_method { |
c9b8b7f9 |
389 | my ($self, $method_name) = @_; |
0882828e |
390 | (defined $method_name && $method_name) |
391 | || confess "You must define a method name"; |
392 | |
2d711cc8 |
393 | return unless $self->has_method($method_name); |
de19f115 |
394 | |
0882828e |
395 | no strict 'refs'; |
de19f115 |
396 | return \&{$self->name . '::' . $method_name}; |
c9b8b7f9 |
397 | } |
398 | |
399 | sub remove_method { |
400 | my ($self, $method_name) = @_; |
401 | (defined $method_name && $method_name) |
402 | || confess "You must define a method name"; |
403 | |
404 | my $removed_method = $self->get_method($method_name); |
405 | |
406 | no strict 'refs'; |
407 | delete ${$self->name . '::'}{$method_name} |
408 | if defined $removed_method; |
409 | |
410 | return $removed_method; |
411 | } |
412 | |
413 | sub get_method_list { |
414 | my $self = shift; |
415 | no strict 'refs'; |
84e3c630 |
416 | grep { $self->has_method($_) } keys %{$self->name . '::'}; |
a5eca695 |
417 | } |
418 | |
419 | sub compute_all_applicable_methods { |
420 | my $self = shift; |
421 | my @methods; |
422 | # keep a record of what we have seen |
423 | # here, this will handle all the |
424 | # inheritence issues because we are |
425 | # using the &class_precedence_list |
426 | my (%seen_class, %seen_method); |
427 | foreach my $class ($self->class_precedence_list()) { |
428 | next if $seen_class{$class}; |
429 | $seen_class{$class}++; |
430 | # fetch the meta-class ... |
431 | my $meta = $self->initialize($class); |
432 | foreach my $method_name ($meta->get_method_list()) { |
433 | next if exists $seen_method{$method_name}; |
434 | $seen_method{$method_name}++; |
435 | push @methods => { |
436 | name => $method_name, |
437 | class => $class, |
438 | code => $meta->get_method($method_name) |
439 | }; |
440 | } |
441 | } |
442 | return @methods; |
443 | } |
444 | |
a5eca695 |
445 | sub find_all_methods_by_name { |
446 | my ($self, $method_name) = @_; |
447 | (defined $method_name && $method_name) |
448 | || confess "You must define a method name to find"; |
449 | my @methods; |
450 | # keep a record of what we have seen |
451 | # here, this will handle all the |
452 | # inheritence issues because we are |
453 | # using the &class_precedence_list |
454 | my %seen_class; |
455 | foreach my $class ($self->class_precedence_list()) { |
456 | next if $seen_class{$class}; |
457 | $seen_class{$class}++; |
458 | # fetch the meta-class ... |
96ceced8 |
459 | my $meta = $self->initialize($class); |
a5eca695 |
460 | push @methods => { |
461 | name => $method_name, |
462 | class => $class, |
463 | code => $meta->get_method($method_name) |
464 | } if $meta->has_method($method_name); |
465 | } |
466 | return @methods; |
8b978dd5 |
467 | } |
468 | |
96ceced8 |
469 | sub find_next_method_by_name { |
470 | my ($self, $method_name) = @_; |
471 | (defined $method_name && $method_name) |
2d711cc8 |
472 | || confess "You must define a method name to find"; |
96ceced8 |
473 | # keep a record of what we have seen |
474 | # here, this will handle all the |
475 | # inheritence issues because we are |
476 | # using the &class_precedence_list |
477 | my %seen_class; |
2d711cc8 |
478 | my @cpl = $self->class_precedence_list(); |
479 | shift @cpl; # discard ourselves |
96ceced8 |
480 | foreach my $class (@cpl) { |
481 | next if $seen_class{$class}; |
482 | $seen_class{$class}++; |
483 | # fetch the meta-class ... |
484 | my $meta = $self->initialize($class); |
2d711cc8 |
485 | return $meta->get_method($method_name) |
486 | if $meta->has_method($method_name); |
96ceced8 |
487 | } |
2d711cc8 |
488 | return; |
96ceced8 |
489 | } |
490 | |
552e3d24 |
491 | ## Attributes |
492 | |
e16da3e6 |
493 | sub add_attribute { |
2e41896e |
494 | my $self = shift; |
495 | # either we have an attribute object already |
496 | # or we need to create one from the args provided |
497 | my $attribute = blessed($_[0]) ? $_[0] : $self->attribute_metaclass->new(@_); |
498 | # make sure it is derived from the correct type though |
499 | ($attribute->isa('Class::MOP::Attribute')) |
500 | || confess "Your attribute must be an instance of Class::MOP::Attribute (or a subclass)"; |
9ec169fe |
501 | $attribute->attach_to_class($self); |
2d711cc8 |
502 | $attribute->install_accessors(); |
291073fc |
503 | $self->get_attribute_map->{$attribute->name} = $attribute; |
9a1b7913 |
504 | |
505 | # FIXME |
506 | # in theory we have to tell everyone the slot structure may have changed |
e16da3e6 |
507 | } |
508 | |
509 | sub has_attribute { |
510 | my ($self, $attribute_name) = @_; |
511 | (defined $attribute_name && $attribute_name) |
512 | || confess "You must define an attribute name"; |
291073fc |
513 | exists $self->get_attribute_map->{$attribute_name} ? 1 : 0; |
e16da3e6 |
514 | } |
515 | |
516 | sub get_attribute { |
517 | my ($self, $attribute_name) = @_; |
518 | (defined $attribute_name && $attribute_name) |
519 | || confess "You must define an attribute name"; |
f7259199 |
520 | return $self->get_attribute_map->{$attribute_name} |
521 | if $self->has_attribute($attribute_name); |
22286063 |
522 | return; |
e16da3e6 |
523 | } |
524 | |
525 | sub remove_attribute { |
526 | my ($self, $attribute_name) = @_; |
527 | (defined $attribute_name && $attribute_name) |
528 | || confess "You must define an attribute name"; |
7b31baf4 |
529 | my $removed_attribute = $self->get_attribute_map->{$attribute_name}; |
22286063 |
530 | return unless defined $removed_attribute; |
531 | delete $self->get_attribute_map->{$attribute_name}; |
2d711cc8 |
532 | $removed_attribute->remove_accessors(); |
2d711cc8 |
533 | $removed_attribute->detach_from_class(); |
e16da3e6 |
534 | return $removed_attribute; |
535 | } |
536 | |
537 | sub get_attribute_list { |
538 | my $self = shift; |
f7259199 |
539 | keys %{$self->get_attribute_map}; |
e16da3e6 |
540 | } |
541 | |
542 | sub compute_all_applicable_attributes { |
543 | my $self = shift; |
544 | my @attrs; |
545 | # keep a record of what we have seen |
546 | # here, this will handle all the |
547 | # inheritence issues because we are |
548 | # using the &class_precedence_list |
549 | my (%seen_class, %seen_attr); |
550 | foreach my $class ($self->class_precedence_list()) { |
551 | next if $seen_class{$class}; |
552 | $seen_class{$class}++; |
553 | # fetch the meta-class ... |
f7259199 |
554 | my $meta = $self->initialize($class); |
e16da3e6 |
555 | foreach my $attr_name ($meta->get_attribute_list()) { |
556 | next if exists $seen_attr{$attr_name}; |
557 | $seen_attr{$attr_name}++; |
c9e77dbb |
558 | push @attrs => $meta->get_attribute($attr_name); |
e16da3e6 |
559 | } |
560 | } |
561 | return @attrs; |
562 | } |
2eb717d5 |
563 | |
058c1cf5 |
564 | sub find_attribute_by_name { |
565 | my ($self, $attr_name) = @_; |
566 | # keep a record of what we have seen |
567 | # here, this will handle all the |
568 | # inheritence issues because we are |
569 | # using the &class_precedence_list |
570 | my %seen_class; |
571 | foreach my $class ($self->class_precedence_list()) { |
572 | next if $seen_class{$class}; |
573 | $seen_class{$class}++; |
574 | # fetch the meta-class ... |
575 | my $meta = $self->initialize($class); |
576 | return $meta->get_attribute($attr_name) |
577 | if $meta->has_attribute($attr_name); |
578 | } |
579 | return; |
580 | } |
581 | |
52e8a34c |
582 | # Class attributes |
583 | |
584 | sub add_package_variable { |
585 | my ($self, $variable, $initial_value) = @_; |
586 | (defined $variable && $variable =~ /^[\$\@\%]/) |
587 | || confess "variable name does not have a sigil"; |
588 | |
589 | my ($sigil, $name) = ($variable =~ /^(.)(.*)$/); |
590 | if (defined $initial_value) { |
591 | no strict 'refs'; |
592 | *{$self->name . '::' . $name} = $initial_value; |
593 | } |
594 | else { |
39ec4f0c |
595 | my $e; |
596 | { |
597 | # NOTE: |
598 | # We HAVE to localize $@ or all |
599 | # hell breaks loose. It is not |
600 | # good, believe me, not good. |
601 | local $@; |
602 | eval $sigil . $self->name . '::' . $name; |
603 | $e = $@ if $@; |
604 | } |
605 | confess "Could not create package variable ($variable) because : $e" if $e; |
52e8a34c |
606 | } |
607 | } |
608 | |
609 | sub has_package_variable { |
610 | my ($self, $variable) = @_; |
611 | (defined $variable && $variable =~ /^[\$\@\%]/) |
612 | || confess "variable name does not have a sigil"; |
613 | my ($sigil, $name) = ($variable =~ /^(.)(.*)$/); |
614 | no strict 'refs'; |
615 | defined ${$self->name . '::'}{$name} ? 1 : 0; |
616 | } |
617 | |
618 | sub get_package_variable { |
619 | my ($self, $variable) = @_; |
620 | (defined $variable && $variable =~ /^[\$\@\%]/) |
621 | || confess "variable name does not have a sigil"; |
622 | my ($sigil, $name) = ($variable =~ /^(.)(.*)$/); |
39ec4f0c |
623 | my ($ref, $e); |
624 | { |
625 | # NOTE: |
626 | # We HAVE to localize $@ or all |
627 | # hell breaks loose. It is not |
628 | # good, believe me, not good. |
629 | local $@; |
630 | $ref = eval '\\' . $sigil . $self->name . '::' . $name; |
631 | $e = $@ if $@; |
632 | } |
633 | confess "Could not get the package variable ($variable) because : $e" if $e; |
52e8a34c |
634 | # if we didn't die, then we can return it |
2d711cc8 |
635 | return $ref; |
52e8a34c |
636 | } |
637 | |
638 | sub remove_package_variable { |
639 | my ($self, $variable) = @_; |
640 | (defined $variable && $variable =~ /^[\$\@\%]/) |
641 | || confess "variable name does not have a sigil"; |
642 | my ($sigil, $name) = ($variable =~ /^(.)(.*)$/); |
643 | no strict 'refs'; |
644 | delete ${$self->name . '::'}{$name}; |
645 | } |
646 | |
8b978dd5 |
647 | 1; |
648 | |
649 | __END__ |
650 | |
651 | =pod |
652 | |
653 | =head1 NAME |
654 | |
655 | Class::MOP::Class - Class Meta Object |
656 | |
657 | =head1 SYNOPSIS |
658 | |
8c936afc |
659 | # assuming that class Foo |
660 | # has been defined, you can |
661 | |
fe122940 |
662 | # use this for introspection ... |
663 | |
fe122940 |
664 | # add a method to Foo ... |
665 | Foo->meta->add_method('bar' => sub { ... }) |
666 | |
667 | # get a list of all the classes searched |
668 | # the method dispatcher in the correct order |
669 | Foo->meta->class_precedence_list() |
670 | |
671 | # remove a method from Foo |
672 | Foo->meta->remove_method('bar'); |
673 | |
674 | # or use this to actually create classes ... |
675 | |
676 | Class::MOP::Class->create('Bar' => '0.01' => ( |
677 | superclasses => [ 'Foo' ], |
678 | attributes => [ |
679 | Class::MOP:::Attribute->new('$bar'), |
680 | Class::MOP:::Attribute->new('$baz'), |
681 | ], |
682 | methods => { |
683 | calculate_bar => sub { ... }, |
684 | construct_baz => sub { ... } |
685 | } |
686 | )); |
687 | |
8b978dd5 |
688 | =head1 DESCRIPTION |
689 | |
fe122940 |
690 | This is the largest and currently most complex part of the Perl 5 |
691 | meta-object protocol. It controls the introspection and |
692 | manipulation of Perl 5 classes (and it can create them too). The |
693 | best way to understand what this module can do, is to read the |
694 | documentation for each of it's methods. |
695 | |
552e3d24 |
696 | =head1 METHODS |
697 | |
2eb717d5 |
698 | =head2 Self Introspection |
699 | |
700 | =over 4 |
701 | |
702 | =item B<meta> |
703 | |
fe122940 |
704 | This will return a B<Class::MOP::Class> instance which is related |
705 | to this class. Thereby allowing B<Class::MOP::Class> to actually |
706 | introspect itself. |
707 | |
708 | As with B<Class::MOP::Attribute>, B<Class::MOP> will actually |
709 | bootstrap this module by installing a number of attribute meta-objects |
710 | into it's metaclass. This will allow this class to reap all the benifits |
711 | of the MOP when subclassing it. |
2eb717d5 |
712 | |
587aca23 |
713 | =item B<get_all_metaclasses> |
714 | |
715 | This will return an hash of all the metaclass instances that have |
716 | been cached by B<Class::MOP::Class> keyed by the package name. |
717 | |
718 | =item B<get_all_metaclass_instances> |
719 | |
720 | This will return an array of all the metaclass instances that have |
721 | been cached by B<Class::MOP::Class>. |
722 | |
723 | =item B<get_all_metaclass_names> |
724 | |
725 | This will return an array of all the metaclass names that have |
726 | been cached by B<Class::MOP::Class>. |
727 | |
2eb717d5 |
728 | =back |
729 | |
552e3d24 |
730 | =head2 Class construction |
731 | |
a2e85e6c |
732 | These methods will handle creating B<Class::MOP::Class> objects, |
733 | which can be used to both create new classes, and analyze |
734 | pre-existing classes. |
552e3d24 |
735 | |
736 | This module will internally store references to all the instances |
737 | you create with these methods, so that they do not need to be |
738 | created any more than nessecary. Basically, they are singletons. |
739 | |
740 | =over 4 |
741 | |
742 | =item B<create ($package_name, ?$package_version, |
a2e85e6c |
743 | superclasses =E<gt> ?@superclasses, |
744 | methods =E<gt> ?%methods, |
745 | attributes =E<gt> ?%attributes)> |
552e3d24 |
746 | |
a2e85e6c |
747 | This returns a B<Class::MOP::Class> object, bringing the specified |
552e3d24 |
748 | C<$package_name> into existence and adding any of the |
749 | C<$package_version>, C<@superclasses>, C<%methods> and C<%attributes> |
750 | to it. |
751 | |
587aca23 |
752 | =item B<create_anon_class (superclasses =E<gt> ?@superclasses, |
753 | methods =E<gt> ?%methods, |
754 | attributes =E<gt> ?%attributes)> |
755 | |
756 | This will create an anonymous class, it works much like C<create> but |
757 | it does not need a C<$package_name>. Instead it will create a suitably |
758 | unique package name for you to stash things into. |
759 | |
552e3d24 |
760 | =item B<initialize ($package_name)> |
761 | |
a2e85e6c |
762 | This initializes and returns returns a B<Class::MOP::Class> object |
763 | for a given a C<$package_name>. |
764 | |
651955fb |
765 | =item B<construct_class_instance (%options)> |
a2e85e6c |
766 | |
767 | This will construct an instance of B<Class::MOP::Class>, it is |
768 | here so that we can actually "tie the knot" for B<Class::MOP::Class> |
769 | to use C<construct_instance> once all the bootstrapping is done. This |
770 | method is used internally by C<initialize> and should never be called |
771 | from outside of that method really. |
552e3d24 |
772 | |
550d56db |
773 | =item B<check_metaclass_compatability> |
774 | |
775 | This method is called as the very last thing in the |
776 | C<construct_class_instance> method. This will check that the |
777 | metaclass you are creating is compatible with the metaclasses of all |
778 | your ancestors. For more inforamtion about metaclass compatibility |
779 | see the C<About Metaclass compatibility> section in L<Class::MOP>. |
780 | |
552e3d24 |
781 | =back |
782 | |
c9e77dbb |
783 | =head2 Object instance construction and cloning |
a2e85e6c |
784 | |
c9e77dbb |
785 | These methods are B<entirely optional>, it is up to you whether you want |
786 | to use them or not. |
552e3d24 |
787 | |
788 | =over 4 |
789 | |
2bab2be6 |
790 | =item B<instance_metaclass> |
791 | |
2d711cc8 |
792 | =item B<get_meta_instance> |
793 | |
5f3c057a |
794 | =item B<new_object (%params)> |
795 | |
796 | This is a convience method for creating a new object of the class, and |
797 | blessing it into the appropriate package as well. Ideally your class |
798 | would call a C<new> this method like so: |
799 | |
800 | sub MyClass::new { |
801 | my ($class, %param) = @_; |
802 | $class->meta->new_object(%params); |
803 | } |
804 | |
805 | Of course the ideal place for this would actually be in C<UNIVERSAL::> |
806 | but that is considered bad style, so we do not do that. |
807 | |
cbd9f942 |
808 | =item B<construct_instance (%params)> |
552e3d24 |
809 | |
c9e77dbb |
810 | This method is used to construct an instace structure suitable for |
811 | C<bless>-ing into your package of choice. It works in conjunction |
812 | with the Attribute protocol to collect all applicable attributes. |
813 | |
cbd9f942 |
814 | This will construct and instance using a HASH ref as storage |
552e3d24 |
815 | (currently only HASH references are supported). This will collect all |
a2e85e6c |
816 | the applicable attributes and layout out the fields in the HASH ref, |
817 | it will then initialize them using either use the corresponding key |
818 | in C<%params> or any default value or initializer found in the |
819 | attribute meta-object. |
727919c5 |
820 | |
5f3c057a |
821 | =item B<clone_object ($instance, %params)> |
822 | |
823 | This is a convience method for cloning an object instance, then |
19d4b5b8 |
824 | blessing it into the appropriate package. This method will call |
825 | C<clone_instance>, which performs a shallow copy of the object, |
826 | see that methods documentation for more details. Ideally your |
827 | class would call a C<clone> this method like so: |
5f3c057a |
828 | |
829 | sub MyClass::clone { |
830 | my ($self, %param) = @_; |
831 | $self->meta->clone_object($self, %params); |
832 | } |
833 | |
834 | Of course the ideal place for this would actually be in C<UNIVERSAL::> |
835 | but that is considered bad style, so we do not do that. |
836 | |
c9e77dbb |
837 | =item B<clone_instance($instance, %params)> |
838 | |
839 | This method is a compliment of C<construct_instance> (which means if |
19d4b5b8 |
840 | you override C<construct_instance>, you need to override this one too), |
841 | and clones the instance shallowly. |
a27ae83f |
842 | |
843 | The cloned structure returned is (like with C<construct_instance>) an |
844 | unC<bless>ed HASH reference, it is your responsibility to then bless |
845 | this cloned structure into the right class (which C<clone_object> will |
846 | do for you). |
c9e77dbb |
847 | |
19d4b5b8 |
848 | As of 0.11, this method will clone the C<$instance> structure shallowly, |
849 | as opposed to the deep cloning implemented in prior versions. After much |
850 | thought, research and discussion, I have decided that anything but basic |
851 | shallow cloning is outside the scope of the meta-object protocol. I |
852 | think Yuval "nothingmuch" Kogman put it best when he said that cloning |
853 | is too I<context-specific> to be part of the MOP. |
854 | |
552e3d24 |
855 | =back |
856 | |
857 | =head2 Informational |
858 | |
859 | =over 4 |
860 | |
861 | =item B<name> |
862 | |
a2e85e6c |
863 | This is a read-only attribute which returns the package name for the |
864 | given B<Class::MOP::Class> instance. |
552e3d24 |
865 | |
866 | =item B<version> |
867 | |
868 | This is a read-only attribute which returns the C<$VERSION> of the |
a2e85e6c |
869 | package for the given B<Class::MOP::Class> instance. |
552e3d24 |
870 | |
871 | =back |
872 | |
873 | =head2 Inheritance Relationships |
874 | |
875 | =over 4 |
876 | |
877 | =item B<superclasses (?@superclasses)> |
878 | |
879 | This is a read-write attribute which represents the superclass |
a2e85e6c |
880 | relationships of the class the B<Class::MOP::Class> instance is |
881 | associated with. Basically, it can get and set the C<@ISA> for you. |
552e3d24 |
882 | |
343203ee |
883 | B<NOTE:> |
884 | Perl will occasionally perform some C<@ISA> and method caching, if |
885 | you decide to change your superclass relationship at runtime (which |
886 | is quite insane and very much not recommened), then you should be |
887 | aware of this and the fact that this module does not make any |
888 | attempt to address this issue. |
889 | |
552e3d24 |
890 | =item B<class_precedence_list> |
891 | |
a2e85e6c |
892 | This computes the a list of all the class's ancestors in the same order |
893 | in which method dispatch will be done. This is similair to |
894 | what B<Class::ISA::super_path> does, but we don't remove duplicate names. |
552e3d24 |
895 | |
896 | =back |
897 | |
898 | =head2 Methods |
899 | |
900 | =over 4 |
901 | |
2e41896e |
902 | =item B<method_metaclass> |
903 | |
552e3d24 |
904 | =item B<add_method ($method_name, $method)> |
905 | |
906 | This will take a C<$method_name> and CODE reference to that |
a2e85e6c |
907 | C<$method> and install it into the class's package. |
552e3d24 |
908 | |
a2e85e6c |
909 | B<NOTE>: |
910 | This does absolutely nothing special to C<$method> |
552e3d24 |
911 | other than use B<Sub::Name> to make sure it is tagged with the |
912 | correct name, and therefore show up correctly in stack traces and |
913 | such. |
914 | |
663f8198 |
915 | =item B<alias_method ($method_name, $method)> |
916 | |
917 | This will take a C<$method_name> and CODE reference to that |
918 | C<$method> and alias the method into the class's package. |
919 | |
920 | B<NOTE>: |
921 | Unlike C<add_method>, this will B<not> try to name the |
922 | C<$method> using B<Sub::Name>, it only aliases the method in |
923 | the class's package. |
924 | |
552e3d24 |
925 | =item B<has_method ($method_name)> |
926 | |
a2e85e6c |
927 | This just provides a simple way to check if the class implements |
552e3d24 |
928 | a specific C<$method_name>. It will I<not> however, attempt to check |
a2e85e6c |
929 | if the class inherits the method (use C<UNIVERSAL::can> for that). |
552e3d24 |
930 | |
931 | This will correctly handle functions defined outside of the package |
932 | that use a fully qualified name (C<sub Package::name { ... }>). |
933 | |
934 | This will correctly handle functions renamed with B<Sub::Name> and |
935 | installed using the symbol tables. However, if you are naming the |
936 | subroutine outside of the package scope, you must use the fully |
937 | qualified name, including the package name, for C<has_method> to |
938 | correctly identify it. |
939 | |
940 | This will attempt to correctly ignore functions imported from other |
941 | packages using B<Exporter>. It breaks down if the function imported |
942 | is an C<__ANON__> sub (such as with C<use constant>), which very well |
943 | may be a valid method being applied to the class. |
944 | |
945 | In short, this method cannot always be trusted to determine if the |
946 | C<$method_name> is actually a method. However, it will DWIM about |
a2e85e6c |
947 | 90% of the time, so it's a small trade off I think. |
552e3d24 |
948 | |
949 | =item B<get_method ($method_name)> |
950 | |
951 | This will return a CODE reference of the specified C<$method_name>, |
952 | or return undef if that method does not exist. |
953 | |
954 | =item B<remove_method ($method_name)> |
955 | |
a2e85e6c |
956 | This will attempt to remove a given C<$method_name> from the class. |
552e3d24 |
957 | It will return the CODE reference that it has removed, and will |
958 | attempt to use B<Sub::Name> to clear the methods associated name. |
959 | |
960 | =item B<get_method_list> |
961 | |
962 | This will return a list of method names for all I<locally> defined |
963 | methods. It does B<not> provide a list of all applicable methods, |
964 | including any inherited ones. If you want a list of all applicable |
965 | methods, use the C<compute_all_applicable_methods> method. |
966 | |
967 | =item B<compute_all_applicable_methods> |
968 | |
a2e85e6c |
969 | This will return a list of all the methods names this class will |
970 | respond to, taking into account inheritance. The list will be a list of |
552e3d24 |
971 | HASH references, each one containing the following information; method |
972 | name, the name of the class in which the method lives and a CODE |
973 | reference for the actual method. |
974 | |
975 | =item B<find_all_methods_by_name ($method_name)> |
976 | |
977 | This will traverse the inheritence hierarchy and locate all methods |
978 | with a given C<$method_name>. Similar to |
979 | C<compute_all_applicable_methods> it returns a list of HASH references |
980 | with the following information; method name (which will always be the |
981 | same as C<$method_name>), the name of the class in which the method |
982 | lives and a CODE reference for the actual method. |
983 | |
984 | The list of methods produced is a distinct list, meaning there are no |
985 | duplicates in it. This is especially useful for things like object |
986 | initialization and destruction where you only want the method called |
987 | once, and in the correct order. |
988 | |
96ceced8 |
989 | =item B<find_next_method_by_name ($method_name)> |
990 | |
991 | This will return the first method to match a given C<$method_name> in |
992 | the superclasses, this is basically equivalent to calling |
993 | C<SUPER::$method_name>, but it can be dispatched at runtime. |
994 | |
552e3d24 |
995 | =back |
996 | |
a4258ffd |
997 | =head2 Method Modifiers |
998 | |
96ceced8 |
999 | Method modifiers are a concept borrowed from CLOS, in which a method |
1000 | can be wrapped with I<before>, I<after> and I<around> method modifiers |
1001 | that will be called everytime the method is called. |
1002 | |
1003 | =head3 How method modifiers work? |
1004 | |
1005 | Method modifiers work by wrapping the original method and then replacing |
1006 | it in the classes symbol table. The wrappers will handle calling all the |
1007 | modifiers in the appropariate orders and preserving the calling context |
1008 | for the original method. |
1009 | |
1010 | Each method modifier serves a particular purpose, which may not be |
1011 | obvious to users of other method wrapping modules. To start with, the |
1012 | return values of I<before> and I<after> modifiers are ignored. This is |
1013 | because thier purpose is B<not> to filter the input and output of the |
1014 | primary method (this is done with an I<around> modifier). This may seem |
1015 | like an odd restriction to some, but doing this allows for simple code |
1016 | to be added at the begining or end of a method call without jeapordizing |
1017 | the normal functioning of the primary method or placing any extra |
1018 | responsibility on the code of the modifier. Of course if you have more |
1019 | complex needs, then use the I<around> modifier, which uses a variation |
1020 | of continutation passing style to allow for a high degree of flexibility. |
1021 | |
1022 | Before and around modifiers are called in last-defined-first-called order, |
1023 | while after modifiers are called in first-defined-first-called order. So |
1024 | the call tree might looks something like this: |
1025 | |
1026 | before 2 |
1027 | before 1 |
1028 | around 2 |
1029 | around 1 |
1030 | primary |
1031 | after 1 |
1032 | after 2 |
1033 | |
1034 | To see examples of using method modifiers, see the following examples |
1035 | included in the distribution; F<InstanceCountingClass>, F<Perl6Attribute>, |
1036 | F<AttributesWithHistory> and F<C3MethodDispatchOrder>. There is also a |
1037 | classic CLOS usage example in the test F<017_add_method_modifier.t>. |
1038 | |
1039 | =head3 What is the performance impact? |
1040 | |
1041 | Of course there is a performance cost associated with method modifiers, |
1042 | but we have made every effort to make that cost be directly proportional |
1043 | to the amount of modifier features you utilize. |
1044 | |
1045 | The wrapping method does it's best to B<only> do as much work as it |
1046 | absolutely needs to. In order to do this we have moved some of the |
1047 | performance costs to set-up time, where they are easier to amortize. |
1048 | |
1049 | All this said, my benchmarks have indicated the following: |
1050 | |
1051 | simple wrapper with no modifiers 100% slower |
1052 | simple wrapper with simple before modifier 400% slower |
1053 | simple wrapper with simple after modifier 450% slower |
1054 | simple wrapper with simple around modifier 500-550% slower |
1055 | simple wrapper with all 3 modifiers 1100% slower |
1056 | |
1057 | These numbers may seem daunting, but you must remember, every feature |
1058 | comes with some cost. To put things in perspective, just doing a simple |
1059 | C<AUTOLOAD> which does nothing but extract the name of the method called |
1060 | and return it costs about 400% over a normal method call. |
1061 | |
a4258ffd |
1062 | =over 4 |
1063 | |
1064 | =item B<add_before_method_modifier ($method_name, $code)> |
1065 | |
96ceced8 |
1066 | This will wrap the method at C<$method_name> and the supplied C<$code> |
1067 | will be passed the C<@_> arguments, and called before the original |
1068 | method is called. As specified above, the return value of the I<before> |
1069 | method modifiers is ignored, and it's ability to modify C<@_> is |
1070 | fairly limited. If you need to do either of these things, use an |
1071 | C<around> method modifier. |
1072 | |
a4258ffd |
1073 | =item B<add_after_method_modifier ($method_name, $code)> |
1074 | |
96ceced8 |
1075 | This will wrap the method at C<$method_name> so that the original |
1076 | method will be called, it's return values stashed, and then the |
1077 | supplied C<$code> will be passed the C<@_> arguments, and called. |
1078 | As specified above, the return value of the I<after> method |
1079 | modifiers is ignored, and it cannot modify the return values of |
1080 | the original method. If you need to do either of these things, use an |
1081 | C<around> method modifier. |
1082 | |
a4258ffd |
1083 | =item B<add_around_method_modifier ($method_name, $code)> |
1084 | |
96ceced8 |
1085 | This will wrap the method at C<$method_name> so that C<$code> |
1086 | will be called and passed the original method as an extra argument |
1087 | at the begining of the C<@_> argument list. This is a variation of |
1088 | continuation passing style, where the function prepended to C<@_> |
1089 | can be considered a continuation. It is up to C<$code> if it calls |
1090 | the original method or not, there is no restriction on what the |
1091 | C<$code> can or cannot do. |
1092 | |
a4258ffd |
1093 | =back |
1094 | |
552e3d24 |
1095 | =head2 Attributes |
1096 | |
1097 | It should be noted that since there is no one consistent way to define |
1098 | the attributes of a class in Perl 5. These methods can only work with |
1099 | the information given, and can not easily discover information on |
a2e85e6c |
1100 | their own. See L<Class::MOP::Attribute> for more details. |
552e3d24 |
1101 | |
1102 | =over 4 |
1103 | |
2e41896e |
1104 | =item B<attribute_metaclass> |
1105 | |
7b31baf4 |
1106 | =item B<get_attribute_map> |
1107 | |
552e3d24 |
1108 | =item B<add_attribute ($attribute_name, $attribute_meta_object)> |
1109 | |
a2e85e6c |
1110 | This stores a C<$attribute_meta_object> in the B<Class::MOP::Class> |
1111 | instance associated with the given class, and associates it with |
1112 | the C<$attribute_name>. Unlike methods, attributes within the MOP |
1113 | are stored as meta-information only. They will be used later to |
1114 | construct instances from (see C<construct_instance> above). |
552e3d24 |
1115 | More details about the attribute meta-objects can be found in the |
a2e85e6c |
1116 | L<Class::MOP::Attribute> or the L<Class::MOP/The Attribute protocol> |
1117 | section. |
1118 | |
1119 | It should be noted that any accessor, reader/writer or predicate |
1120 | methods which the C<$attribute_meta_object> has will be installed |
1121 | into the class at this time. |
552e3d24 |
1122 | |
1123 | =item B<has_attribute ($attribute_name)> |
1124 | |
a2e85e6c |
1125 | Checks to see if this class has an attribute by the name of |
552e3d24 |
1126 | C<$attribute_name> and returns a boolean. |
1127 | |
1128 | =item B<get_attribute ($attribute_name)> |
1129 | |
1130 | Returns the attribute meta-object associated with C<$attribute_name>, |
1131 | if none is found, it will return undef. |
1132 | |
1133 | =item B<remove_attribute ($attribute_name)> |
1134 | |
1135 | This will remove the attribute meta-object stored at |
1136 | C<$attribute_name>, then return the removed attribute meta-object. |
1137 | |
a2e85e6c |
1138 | B<NOTE:> |
1139 | Removing an attribute will only affect future instances of |
552e3d24 |
1140 | the class, it will not make any attempt to remove the attribute from |
1141 | any existing instances of the class. |
1142 | |
a2e85e6c |
1143 | It should be noted that any accessor, reader/writer or predicate |
1144 | methods which the attribute meta-object stored at C<$attribute_name> |
1145 | has will be removed from the class at this time. This B<will> make |
1146 | these attributes somewhat inaccessable in previously created |
1147 | instances. But if you are crazy enough to do this at runtime, then |
1148 | you are crazy enough to deal with something like this :). |
1149 | |
552e3d24 |
1150 | =item B<get_attribute_list> |
1151 | |
1152 | This returns a list of attribute names which are defined in the local |
1153 | class. If you want a list of all applicable attributes for a class, |
1154 | use the C<compute_all_applicable_attributes> method. |
1155 | |
1156 | =item B<compute_all_applicable_attributes> |
1157 | |
c9e77dbb |
1158 | This will traverse the inheritance heirachy and return a list of all |
1159 | the applicable attributes for this class. It does not construct a |
1160 | HASH reference like C<compute_all_applicable_methods> because all |
1161 | that same information is discoverable through the attribute |
1162 | meta-object itself. |
552e3d24 |
1163 | |
058c1cf5 |
1164 | =item B<find_attribute_by_name ($attr_name)> |
1165 | |
1166 | This method will traverse the inheritance heirachy and find the |
1167 | first attribute whose name matches C<$attr_name>, then return it. |
1168 | It will return undef if nothing is found. |
1169 | |
552e3d24 |
1170 | =back |
1171 | |
52e8a34c |
1172 | =head2 Package Variables |
1173 | |
1174 | Since Perl's classes are built atop the Perl package system, it is |
1175 | fairly common to use package scoped variables for things like static |
1176 | class variables. The following methods are convience methods for |
1177 | the creation and inspection of package scoped variables. |
1178 | |
1179 | =over 4 |
1180 | |
1181 | =item B<add_package_variable ($variable_name, ?$initial_value)> |
1182 | |
1183 | Given a C<$variable_name>, which must contain a leading sigil, this |
1184 | method will create that variable within the package which houses the |
1185 | class. It also takes an optional C<$initial_value>, which must be a |
1186 | reference of the same type as the sigil of the C<$variable_name> |
1187 | implies. |
1188 | |
1189 | =item B<get_package_variable ($variable_name)> |
1190 | |
1191 | This will return a reference to the package variable in |
1192 | C<$variable_name>. |
1193 | |
1194 | =item B<has_package_variable ($variable_name)> |
1195 | |
1196 | Returns true (C<1>) if there is a package variable defined for |
1197 | C<$variable_name>, and false (C<0>) otherwise. |
1198 | |
1199 | =item B<remove_package_variable ($variable_name)> |
1200 | |
1201 | This will attempt to remove the package variable at C<$variable_name>. |
1202 | |
1203 | =back |
1204 | |
8b978dd5 |
1205 | =head1 AUTHOR |
1206 | |
a2e85e6c |
1207 | Stevan Little E<lt>stevan@iinteractive.comE<gt> |
8b978dd5 |
1208 | |
1209 | =head1 COPYRIGHT AND LICENSE |
1210 | |
1211 | Copyright 2006 by Infinity Interactive, Inc. |
1212 | |
1213 | L<http://www.iinteractive.com> |
1214 | |
1215 | This library is free software; you can redistribute it and/or modify |
1216 | it under the same terms as Perl itself. |
1217 | |
9a1b7913 |
1218 | =cutchistian |