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 | |
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 | |
ff43b9d6 |
43 | sub reinitialize { |
44 | my $class = shift; |
45 | my $package_name = shift; |
46 | (defined $package_name && $package_name && !blessed($package_name)) |
47 | || confess "You must pass a package name and it cannot be blessed"; |
48 | $METAS{$package_name} = undef; |
49 | $class->construct_class_instance(':package' => $package_name, @_); |
77e5fce4 |
50 | } |
51 | |
52 | # NOTE: |
53 | # we need a sufficiently annoying prefix |
54 | # this should suffice for now |
55 | my $ANON_CLASS_PREFIX = 'Class::MOP::Class::__ANON__::SERIAL::'; |
56 | |
57 | { |
58 | # NOTE: |
59 | # this should be sufficient, if you have a |
60 | # use case where it is not, write a test and |
61 | # I will change it. |
62 | my $ANON_CLASS_SERIAL = 0; |
63 | |
64 | sub create_anon_class { |
65 | my ($class, %options) = @_; |
66 | my $package_name = $ANON_CLASS_PREFIX . ++$ANON_CLASS_SERIAL; |
67 | return $class->create($package_name, '0.00', %options); |
68 | } |
69 | } |
ff43b9d6 |
70 | |
727919c5 |
71 | # NOTE: (meta-circularity) |
72 | # this is a special form of &construct_instance |
73 | # (see below), which is used to construct class |
1a7ebbb3 |
74 | # meta-object instances for any Class::MOP::* |
75 | # class. All other classes will use the more |
76 | # normal &construct_instance. |
727919c5 |
77 | sub construct_class_instance { |
351bd7d4 |
78 | my $class = shift; |
651955fb |
79 | my %options = @_; |
80 | my $package_name = $options{':package'}; |
727919c5 |
81 | (defined $package_name && $package_name) |
651955fb |
82 | || confess "You must pass a package name"; |
2d711cc8 |
83 | # NOTE: |
84 | # return the metaclass if we have it cached, |
85 | # and it is still defined (it has not been |
86 | # reaped by DESTROY yet, which can happen |
87 | # annoyingly enough during global destruction) |
2f6d5412 |
88 | return $METAS{$package_name} |
2d711cc8 |
89 | if exists $METAS{$package_name} && defined $METAS{$package_name}; |
1a7ebbb3 |
90 | $class = blessed($class) || $class; |
550d56db |
91 | # now create the metaclass |
92 | my $meta; |
1a7ebbb3 |
93 | if ($class =~ /^Class::MOP::/) { |
550d56db |
94 | $meta = bless { |
351bd7d4 |
95 | '$:package' => $package_name, |
96 | '%:attributes' => {}, |
550d56db |
97 | '$:attribute_metaclass' => $options{':attribute_metaclass'} || 'Class::MOP::Attribute', |
2bab2be6 |
98 | '$:method_metaclass' => $options{':method_metaclass'} || 'Class::MOP::Method', |
99 | '$:instance_metaclass' => $options{':instance_metaclass'} || 'Class::MOP::Instance', |
1a7ebbb3 |
100 | } => $class; |
101 | } |
102 | else { |
5f3c057a |
103 | # NOTE: |
104 | # it is safe to use meta here because |
105 | # class will always be a subclass of |
106 | # Class::MOP::Class, which defines meta |
40483095 |
107 | $meta = $class->meta->construct_instance(%options) |
1a7ebbb3 |
108 | } |
550d56db |
109 | # and check the metaclass compatibility |
110 | $meta->check_metaclass_compatability(); |
111 | $METAS{$package_name} = $meta; |
77e5fce4 |
112 | # NOTE: |
113 | # we need to weaken any anon classes |
114 | # so that they can call DESTROY properly |
115 | weaken($METAS{$package_name}) |
116 | if $package_name =~ /^$ANON_CLASS_PREFIX/; |
117 | $meta; |
118 | } |
119 | |
120 | # NOTE: |
121 | # this will only get called for |
122 | # anon-classes, all other calls |
123 | # are assumed to occur during |
124 | # global destruction and so don't |
125 | # really need to be handled explicitly |
126 | sub DESTROY { |
127 | my $self = shift; |
128 | return unless $self->name =~ /^$ANON_CLASS_PREFIX/; |
129 | my ($serial_id) = ($self->name =~ /^$ANON_CLASS_PREFIX(\d+)/); |
130 | no strict 'refs'; |
131 | foreach my $key (keys %{$ANON_CLASS_PREFIX . $serial_id}) { |
132 | delete ${$ANON_CLASS_PREFIX . $serial_id}{$key}; |
133 | } |
134 | delete ${'main::' . $ANON_CLASS_PREFIX}{$serial_id . '::'}; |
550d56db |
135 | } |
136 | |
137 | sub check_metaclass_compatability { |
138 | my $self = shift; |
139 | |
140 | # this is always okay ... |
d82060fe |
141 | return if blessed($self) eq 'Class::MOP::Class' && |
142 | $self->instance_metaclass eq 'Class::MOP::Instance'; |
550d56db |
143 | |
144 | my @class_list = $self->class_precedence_list; |
145 | shift @class_list; # shift off $self->name |
146 | |
147 | foreach my $class_name (@class_list) { |
96ceced8 |
148 | my $meta = $METAS{$class_name} || next; |
550d56db |
149 | ($self->isa(blessed($meta))) |
150 | || confess $self->name . "->meta => (" . (blessed($self)) . ")" . |
151 | " is not compatible with the " . |
152 | $class_name . "->meta => (" . (blessed($meta)) . ")"; |
f7259199 |
153 | # NOTE: |
154 | # we also need to check that instance metaclasses |
155 | # are compatabile in the same the class. |
156 | ($self->instance_metaclass->isa($meta->instance_metaclass)) |
157 | || confess $self->name . "->meta => (" . ($self->instance_metaclass) . ")" . |
158 | " is not compatible with the " . |
159 | $class_name . "->meta => (" . ($meta->instance_metaclass) . ")"; |
550d56db |
160 | } |
fa16e528 |
161 | } |
f7259199 |
162 | } |
8b978dd5 |
163 | |
164 | sub create { |
165 | my ($class, $package_name, $package_version, %options) = @_; |
bfe4d0fc |
166 | (defined $package_name && $package_name) |
8b978dd5 |
167 | || confess "You must pass a package name"; |
168 | my $code = "package $package_name;"; |
169 | $code .= "\$$package_name\:\:VERSION = '$package_version';" |
170 | if defined $package_version; |
171 | eval $code; |
172 | confess "creation of $package_name failed : $@" if $@; |
bfe4d0fc |
173 | my $meta = $class->initialize($package_name); |
aa448b16 |
174 | |
175 | $meta->add_method('meta' => sub { |
176 | Class::MOP::Class->initialize(blessed($_[0]) || $_[0]); |
177 | }); |
178 | |
8b978dd5 |
179 | $meta->superclasses(@{$options{superclasses}}) |
180 | if exists $options{superclasses}; |
2eb717d5 |
181 | # NOTE: |
182 | # process attributes first, so that they can |
183 | # install accessors, but locally defined methods |
184 | # can then overwrite them. It is maybe a little odd, but |
185 | # I think this should be the order of things. |
186 | if (exists $options{attributes}) { |
cbd9f942 |
187 | foreach my $attr (@{$options{attributes}}) { |
188 | $meta->add_attribute($attr); |
2eb717d5 |
189 | } |
190 | } |
bfe4d0fc |
191 | if (exists $options{methods}) { |
192 | foreach my $method_name (keys %{$options{methods}}) { |
193 | $meta->add_method($method_name, $options{methods}->{$method_name}); |
194 | } |
2eb717d5 |
195 | } |
8b978dd5 |
196 | return $meta; |
197 | } |
198 | |
7b31baf4 |
199 | ## Attribute readers |
200 | |
201 | # NOTE: |
202 | # all these attribute readers will be bootstrapped |
203 | # away in the Class::MOP bootstrap section |
204 | |
205 | sub name { $_[0]->{'$:package'} } |
206 | sub get_attribute_map { $_[0]->{'%:attributes'} } |
207 | sub attribute_metaclass { $_[0]->{'$:attribute_metaclass'} } |
208 | sub method_metaclass { $_[0]->{'$:method_metaclass'} } |
2bab2be6 |
209 | sub instance_metaclass { $_[0]->{'$:instance_metaclass'} } |
7b31baf4 |
210 | |
c9e77dbb |
211 | # Instance Construction & Cloning |
212 | |
5f3c057a |
213 | sub new_object { |
214 | my $class = shift; |
651955fb |
215 | # NOTE: |
216 | # we need to protect the integrity of the |
217 | # Class::MOP::Class singletons here, so we |
218 | # delegate this to &construct_class_instance |
219 | # which will deal with the singletons |
220 | return $class->construct_class_instance(@_) |
221 | if $class->name->isa('Class::MOP::Class'); |
24869f62 |
222 | return $class->construct_instance(@_); |
5f3c057a |
223 | } |
e16da3e6 |
224 | |
225 | sub construct_instance { |
cbd9f942 |
226 | my ($class, %params) = @_; |
0e76a376 |
227 | my $meta_instance = $class->get_meta_instance(); |
228 | my $instance = $meta_instance->create_instance(); |
c9e77dbb |
229 | foreach my $attr ($class->compute_all_applicable_attributes()) { |
f892c0f0 |
230 | $attr->initialize_instance_slot($meta_instance, $instance, \%params); |
cbd9f942 |
231 | } |
2d711cc8 |
232 | return $instance; |
233 | } |
234 | |
235 | sub get_meta_instance { |
236 | my $class = shift; |
052c2a1a |
237 | return $class->instance_metaclass->new( |
238 | $class, |
239 | $class->compute_all_applicable_attributes() |
240 | ); |
e16da3e6 |
241 | } |
242 | |
5f3c057a |
243 | sub clone_object { |
244 | my $class = shift; |
7b31baf4 |
245 | my $instance = shift; |
651955fb |
246 | (blessed($instance) && $instance->isa($class->name)) |
247 | || confess "You must pass an instance ($instance) of the metaclass (" . $class->name . ")"; |
248 | # NOTE: |
249 | # we need to protect the integrity of the |
250 | # Class::MOP::Class singletons here, they |
a740253a |
251 | # should not be cloned. |
651955fb |
252 | return $instance if $instance->isa('Class::MOP::Class'); |
f7259199 |
253 | $class->clone_instance($instance, @_); |
5f3c057a |
254 | } |
255 | |
c9e77dbb |
256 | sub clone_instance { |
651955fb |
257 | my ($class, $instance, %params) = @_; |
258 | (blessed($instance)) |
c9e77dbb |
259 | || confess "You can only clone instances, \$self is not a blessed instance"; |
f7259199 |
260 | my $meta_instance = $class->get_meta_instance(); |
261 | my $clone = $meta_instance->clone_instance($instance); |
262 | foreach my $key (%params) { |
263 | next unless $meta_instance->is_valid_slot($key); |
264 | $meta_instance->set_slot_value($clone, $key, $params{$key}); |
265 | } |
c9e77dbb |
266 | return $clone; |
267 | } |
268 | |
8b978dd5 |
269 | # Informational |
270 | |
7b31baf4 |
271 | # &name should be here too, but it is above |
272 | # because it gets bootstrapped away |
8b978dd5 |
273 | |
274 | sub version { |
275 | my $self = shift; |
96ceced8 |
276 | ${$self->get_package_variable('$VERSION')}; |
8b978dd5 |
277 | } |
278 | |
279 | # Inheritance |
280 | |
281 | sub superclasses { |
282 | my $self = shift; |
e7f732e4 |
283 | no strict 'refs'; |
8b978dd5 |
284 | if (@_) { |
285 | my @supers = @_; |
e7f732e4 |
286 | @{$self->name . '::ISA'} = @supers; |
d82060fe |
287 | # NOTE: |
288 | # we need to check the metaclass |
289 | # compatability here so that we can |
290 | # be sure that the superclass is |
291 | # not potentially creating an issues |
292 | # we don't know about |
293 | $self->check_metaclass_compatability(); |
8b978dd5 |
294 | } |
e7f732e4 |
295 | @{$self->name . '::ISA'}; |
8b978dd5 |
296 | } |
297 | |
298 | sub class_precedence_list { |
299 | my $self = shift; |
bfe4d0fc |
300 | # NOTE: |
301 | # We need to check for ciruclar inheirtance here. |
302 | # This will do nothing if all is well, and blow |
303 | # up otherwise. Yes, it's an ugly hack, better |
304 | # suggestions are welcome. |
93b4e576 |
305 | { ($self->name || return)->isa('This is a test for circular inheritance') } |
8c936afc |
306 | # ... and now back to our regularly scheduled program |
8b978dd5 |
307 | ( |
308 | $self->name, |
309 | map { |
f7259199 |
310 | $self->initialize($_)->class_precedence_list() |
8b978dd5 |
311 | } $self->superclasses() |
312 | ); |
313 | } |
314 | |
0882828e |
315 | ## Methods |
316 | |
317 | sub add_method { |
318 | my ($self, $method_name, $method) = @_; |
319 | (defined $method_name && $method_name) |
320 | || confess "You must define a method name"; |
a5eca695 |
321 | # use reftype here to allow for blessed subs ... |
ee5e71d4 |
322 | ('CODE' eq (reftype($method) || '')) |
0882828e |
323 | || confess "Your code block must be a CODE reference"; |
324 | my $full_method_name = ($self->name . '::' . $method_name); |
de19f115 |
325 | |
2d711cc8 |
326 | $method = $self->method_metaclass->wrap($method) unless blessed($method); |
327 | |
0882828e |
328 | no strict 'refs'; |
c9b8b7f9 |
329 | no warnings 'redefine'; |
22286063 |
330 | *{$full_method_name} = subname $full_method_name => $method; |
0882828e |
331 | } |
332 | |
a4258ffd |
333 | { |
2d711cc8 |
334 | my $fetch_and_prepare_method = sub { |
335 | my ($self, $method_name) = @_; |
336 | # fetch it locally |
337 | my $method = $self->get_method($method_name); |
338 | # if we dont have local ... |
339 | unless ($method) { |
340 | # make sure this method even exists ... |
341 | ($self->find_next_method_by_name($method_name)) |
342 | || confess "The method '$method_name' is not found in the inherience hierarchy for this class"; |
343 | # if so, then create a local which just |
344 | # calls the next applicable method ... |
345 | $self->add_method($method_name => sub { |
346 | $self->find_next_method_by_name($method_name)->(@_); |
347 | }); |
348 | $method = $self->get_method($method_name); |
349 | } |
350 | |
351 | # now make sure we wrap it properly |
352 | # (if it isnt already) |
353 | unless ($method->isa('Class::MOP::Method::Wrapped')) { |
354 | $method = Class::MOP::Method::Wrapped->wrap($method); |
355 | $self->add_method($method_name => $method); |
356 | } |
357 | return $method; |
358 | }; |
359 | |
360 | sub add_before_method_modifier { |
361 | my ($self, $method_name, $method_modifier) = @_; |
362 | (defined $method_name && $method_name) |
363 | || confess "You must pass in a method name"; |
364 | my $method = $fetch_and_prepare_method->($self, $method_name); |
365 | $method->add_before_modifier(subname ':before' => $method_modifier); |
366 | } |
367 | |
368 | sub add_after_method_modifier { |
369 | my ($self, $method_name, $method_modifier) = @_; |
370 | (defined $method_name && $method_name) |
371 | || confess "You must pass in a method name"; |
372 | my $method = $fetch_and_prepare_method->($self, $method_name); |
373 | $method->add_after_modifier(subname ':after' => $method_modifier); |
374 | } |
375 | |
376 | sub add_around_method_modifier { |
377 | my ($self, $method_name, $method_modifier) = @_; |
378 | (defined $method_name && $method_name) |
379 | || confess "You must pass in a method name"; |
380 | my $method = $fetch_and_prepare_method->($self, $method_name); |
381 | $method->add_around_modifier(subname ':around' => $method_modifier); |
382 | } |
a4258ffd |
383 | |
8c936afc |
384 | # NOTE: |
385 | # the methods above used to be named like this: |
386 | # ${pkg}::${method}:(before|after|around) |
387 | # but this proved problematic when using one modifier |
388 | # to wrap multiple methods (something which is likely |
389 | # to happen pretty regularly IMO). So instead of naming |
390 | # it like this, I have chosen to just name them purely |
391 | # with their modifier names, like so: |
392 | # :(before|after|around) |
393 | # The fact is that in a stack trace, it will be fairly |
394 | # evident from the context what method they are attached |
395 | # to, and so don't need the fully qualified name. |
ee5e71d4 |
396 | } |
397 | |
663f8198 |
398 | sub alias_method { |
399 | my ($self, $method_name, $method) = @_; |
400 | (defined $method_name && $method_name) |
401 | || confess "You must define a method name"; |
402 | # use reftype here to allow for blessed subs ... |
ee5e71d4 |
403 | ('CODE' eq (reftype($method) || '')) |
663f8198 |
404 | || confess "Your code block must be a CODE reference"; |
de19f115 |
405 | my $full_method_name = ($self->name . '::' . $method_name); |
406 | |
2d711cc8 |
407 | $method = $self->method_metaclass->wrap($method) unless blessed($method); |
663f8198 |
408 | |
409 | no strict 'refs'; |
410 | no warnings 'redefine'; |
411 | *{$full_method_name} = $method; |
412 | } |
413 | |
de19f115 |
414 | sub has_method { |
415 | my ($self, $method_name) = @_; |
416 | (defined $method_name && $method_name) |
417 | || confess "You must define a method name"; |
bfe4d0fc |
418 | |
de19f115 |
419 | my $sub_name = ($self->name . '::' . $method_name); |
0882828e |
420 | |
de19f115 |
421 | no strict 'refs'; |
422 | return 0 if !defined(&{$sub_name}); |
2d711cc8 |
423 | my $method = \&{$sub_name}; |
96ceced8 |
424 | return 0 if (svref_2object($method)->GV->STASH->NAME || '') ne $self->name && |
2d711cc8 |
425 | (svref_2object($method)->GV->NAME || '') ne '__ANON__'; |
426 | |
427 | # at this point we are relatively sure |
428 | # it is our method, so we bless/wrap it |
429 | $self->method_metaclass->wrap($method) unless blessed($method); |
de19f115 |
430 | return 1; |
0882828e |
431 | } |
432 | |
433 | sub get_method { |
c9b8b7f9 |
434 | my ($self, $method_name) = @_; |
0882828e |
435 | (defined $method_name && $method_name) |
436 | || confess "You must define a method name"; |
437 | |
2d711cc8 |
438 | return unless $self->has_method($method_name); |
de19f115 |
439 | |
0882828e |
440 | no strict 'refs'; |
de19f115 |
441 | return \&{$self->name . '::' . $method_name}; |
c9b8b7f9 |
442 | } |
443 | |
444 | sub remove_method { |
445 | my ($self, $method_name) = @_; |
446 | (defined $method_name && $method_name) |
447 | || confess "You must define a method name"; |
448 | |
449 | my $removed_method = $self->get_method($method_name); |
450 | |
451 | no strict 'refs'; |
452 | delete ${$self->name . '::'}{$method_name} |
453 | if defined $removed_method; |
454 | |
455 | return $removed_method; |
456 | } |
457 | |
458 | sub get_method_list { |
459 | my $self = shift; |
460 | no strict 'refs'; |
84e3c630 |
461 | grep { $self->has_method($_) } keys %{$self->name . '::'}; |
a5eca695 |
462 | } |
463 | |
464 | sub compute_all_applicable_methods { |
465 | my $self = shift; |
466 | my @methods; |
467 | # keep a record of what we have seen |
468 | # here, this will handle all the |
469 | # inheritence issues because we are |
470 | # using the &class_precedence_list |
471 | my (%seen_class, %seen_method); |
472 | foreach my $class ($self->class_precedence_list()) { |
473 | next if $seen_class{$class}; |
474 | $seen_class{$class}++; |
475 | # fetch the meta-class ... |
476 | my $meta = $self->initialize($class); |
477 | foreach my $method_name ($meta->get_method_list()) { |
478 | next if exists $seen_method{$method_name}; |
479 | $seen_method{$method_name}++; |
480 | push @methods => { |
481 | name => $method_name, |
482 | class => $class, |
483 | code => $meta->get_method($method_name) |
484 | }; |
485 | } |
486 | } |
487 | return @methods; |
488 | } |
489 | |
a5eca695 |
490 | sub find_all_methods_by_name { |
491 | my ($self, $method_name) = @_; |
492 | (defined $method_name && $method_name) |
493 | || confess "You must define a method name to find"; |
494 | my @methods; |
495 | # keep a record of what we have seen |
496 | # here, this will handle all the |
497 | # inheritence issues because we are |
498 | # using the &class_precedence_list |
499 | my %seen_class; |
500 | foreach my $class ($self->class_precedence_list()) { |
501 | next if $seen_class{$class}; |
502 | $seen_class{$class}++; |
503 | # fetch the meta-class ... |
96ceced8 |
504 | my $meta = $self->initialize($class); |
a5eca695 |
505 | push @methods => { |
506 | name => $method_name, |
507 | class => $class, |
508 | code => $meta->get_method($method_name) |
509 | } if $meta->has_method($method_name); |
510 | } |
511 | return @methods; |
8b978dd5 |
512 | } |
513 | |
96ceced8 |
514 | sub find_next_method_by_name { |
515 | my ($self, $method_name) = @_; |
516 | (defined $method_name && $method_name) |
2d711cc8 |
517 | || confess "You must define a method name to find"; |
96ceced8 |
518 | # keep a record of what we have seen |
519 | # here, this will handle all the |
520 | # inheritence issues because we are |
521 | # using the &class_precedence_list |
522 | my %seen_class; |
2d711cc8 |
523 | my @cpl = $self->class_precedence_list(); |
524 | shift @cpl; # discard ourselves |
96ceced8 |
525 | foreach my $class (@cpl) { |
526 | next if $seen_class{$class}; |
527 | $seen_class{$class}++; |
528 | # fetch the meta-class ... |
529 | my $meta = $self->initialize($class); |
2d711cc8 |
530 | return $meta->get_method($method_name) |
531 | if $meta->has_method($method_name); |
96ceced8 |
532 | } |
2d711cc8 |
533 | return; |
96ceced8 |
534 | } |
535 | |
552e3d24 |
536 | ## Attributes |
537 | |
e16da3e6 |
538 | sub add_attribute { |
2e41896e |
539 | my $self = shift; |
540 | # either we have an attribute object already |
541 | # or we need to create one from the args provided |
542 | my $attribute = blessed($_[0]) ? $_[0] : $self->attribute_metaclass->new(@_); |
543 | # make sure it is derived from the correct type though |
544 | ($attribute->isa('Class::MOP::Attribute')) |
545 | || confess "Your attribute must be an instance of Class::MOP::Attribute (or a subclass)"; |
9ec169fe |
546 | $attribute->attach_to_class($self); |
2d711cc8 |
547 | $attribute->install_accessors(); |
291073fc |
548 | $self->get_attribute_map->{$attribute->name} = $attribute; |
9a1b7913 |
549 | |
550 | # FIXME |
551 | # in theory we have to tell everyone the slot structure may have changed |
e16da3e6 |
552 | } |
553 | |
554 | sub has_attribute { |
555 | my ($self, $attribute_name) = @_; |
556 | (defined $attribute_name && $attribute_name) |
557 | || confess "You must define an attribute name"; |
291073fc |
558 | exists $self->get_attribute_map->{$attribute_name} ? 1 : 0; |
e16da3e6 |
559 | } |
560 | |
561 | sub get_attribute { |
562 | my ($self, $attribute_name) = @_; |
563 | (defined $attribute_name && $attribute_name) |
564 | || confess "You must define an attribute name"; |
f7259199 |
565 | return $self->get_attribute_map->{$attribute_name} |
566 | if $self->has_attribute($attribute_name); |
22286063 |
567 | return; |
e16da3e6 |
568 | } |
569 | |
570 | sub remove_attribute { |
571 | my ($self, $attribute_name) = @_; |
572 | (defined $attribute_name && $attribute_name) |
573 | || confess "You must define an attribute name"; |
7b31baf4 |
574 | my $removed_attribute = $self->get_attribute_map->{$attribute_name}; |
22286063 |
575 | return unless defined $removed_attribute; |
576 | delete $self->get_attribute_map->{$attribute_name}; |
2d711cc8 |
577 | $removed_attribute->remove_accessors(); |
2d711cc8 |
578 | $removed_attribute->detach_from_class(); |
e16da3e6 |
579 | return $removed_attribute; |
580 | } |
581 | |
582 | sub get_attribute_list { |
583 | my $self = shift; |
f7259199 |
584 | keys %{$self->get_attribute_map}; |
e16da3e6 |
585 | } |
586 | |
587 | sub compute_all_applicable_attributes { |
588 | my $self = shift; |
589 | my @attrs; |
590 | # keep a record of what we have seen |
591 | # here, this will handle all the |
592 | # inheritence issues because we are |
593 | # using the &class_precedence_list |
594 | my (%seen_class, %seen_attr); |
595 | foreach my $class ($self->class_precedence_list()) { |
596 | next if $seen_class{$class}; |
597 | $seen_class{$class}++; |
598 | # fetch the meta-class ... |
f7259199 |
599 | my $meta = $self->initialize($class); |
e16da3e6 |
600 | foreach my $attr_name ($meta->get_attribute_list()) { |
601 | next if exists $seen_attr{$attr_name}; |
602 | $seen_attr{$attr_name}++; |
c9e77dbb |
603 | push @attrs => $meta->get_attribute($attr_name); |
e16da3e6 |
604 | } |
605 | } |
606 | return @attrs; |
607 | } |
2eb717d5 |
608 | |
058c1cf5 |
609 | sub find_attribute_by_name { |
610 | my ($self, $attr_name) = @_; |
611 | # keep a record of what we have seen |
612 | # here, this will handle all the |
613 | # inheritence issues because we are |
614 | # using the &class_precedence_list |
615 | my %seen_class; |
616 | foreach my $class ($self->class_precedence_list()) { |
617 | next if $seen_class{$class}; |
618 | $seen_class{$class}++; |
619 | # fetch the meta-class ... |
620 | my $meta = $self->initialize($class); |
621 | return $meta->get_attribute($attr_name) |
622 | if $meta->has_attribute($attr_name); |
623 | } |
624 | return; |
625 | } |
626 | |
52e8a34c |
627 | # Class attributes |
628 | |
629 | sub add_package_variable { |
630 | my ($self, $variable, $initial_value) = @_; |
631 | (defined $variable && $variable =~ /^[\$\@\%]/) |
632 | || confess "variable name does not have a sigil"; |
633 | |
634 | my ($sigil, $name) = ($variable =~ /^(.)(.*)$/); |
635 | if (defined $initial_value) { |
636 | no strict 'refs'; |
637 | *{$self->name . '::' . $name} = $initial_value; |
638 | } |
639 | else { |
39ec4f0c |
640 | my $e; |
641 | { |
642 | # NOTE: |
643 | # We HAVE to localize $@ or all |
644 | # hell breaks loose. It is not |
645 | # good, believe me, not good. |
646 | local $@; |
647 | eval $sigil . $self->name . '::' . $name; |
648 | $e = $@ if $@; |
649 | } |
650 | confess "Could not create package variable ($variable) because : $e" if $e; |
52e8a34c |
651 | } |
652 | } |
653 | |
654 | sub has_package_variable { |
655 | my ($self, $variable) = @_; |
656 | (defined $variable && $variable =~ /^[\$\@\%]/) |
657 | || confess "variable name does not have a sigil"; |
658 | my ($sigil, $name) = ($variable =~ /^(.)(.*)$/); |
659 | no strict 'refs'; |
660 | defined ${$self->name . '::'}{$name} ? 1 : 0; |
661 | } |
662 | |
663 | sub get_package_variable { |
664 | my ($self, $variable) = @_; |
665 | (defined $variable && $variable =~ /^[\$\@\%]/) |
666 | || confess "variable name does not have a sigil"; |
667 | my ($sigil, $name) = ($variable =~ /^(.)(.*)$/); |
39ec4f0c |
668 | my ($ref, $e); |
669 | { |
670 | # NOTE: |
671 | # We HAVE to localize $@ or all |
672 | # hell breaks loose. It is not |
673 | # good, believe me, not good. |
674 | local $@; |
675 | $ref = eval '\\' . $sigil . $self->name . '::' . $name; |
676 | $e = $@ if $@; |
677 | } |
678 | confess "Could not get the package variable ($variable) because : $e" if $e; |
52e8a34c |
679 | # if we didn't die, then we can return it |
2d711cc8 |
680 | return $ref; |
52e8a34c |
681 | } |
682 | |
683 | sub remove_package_variable { |
684 | my ($self, $variable) = @_; |
685 | (defined $variable && $variable =~ /^[\$\@\%]/) |
686 | || confess "variable name does not have a sigil"; |
687 | my ($sigil, $name) = ($variable =~ /^(.)(.*)$/); |
688 | no strict 'refs'; |
689 | delete ${$self->name . '::'}{$name}; |
690 | } |
691 | |
8b978dd5 |
692 | 1; |
693 | |
694 | __END__ |
695 | |
696 | =pod |
697 | |
698 | =head1 NAME |
699 | |
700 | Class::MOP::Class - Class Meta Object |
701 | |
702 | =head1 SYNOPSIS |
703 | |
8c936afc |
704 | # assuming that class Foo |
705 | # has been defined, you can |
706 | |
fe122940 |
707 | # use this for introspection ... |
708 | |
fe122940 |
709 | # add a method to Foo ... |
710 | Foo->meta->add_method('bar' => sub { ... }) |
711 | |
712 | # get a list of all the classes searched |
713 | # the method dispatcher in the correct order |
714 | Foo->meta->class_precedence_list() |
715 | |
716 | # remove a method from Foo |
717 | Foo->meta->remove_method('bar'); |
718 | |
719 | # or use this to actually create classes ... |
720 | |
721 | Class::MOP::Class->create('Bar' => '0.01' => ( |
722 | superclasses => [ 'Foo' ], |
723 | attributes => [ |
724 | Class::MOP:::Attribute->new('$bar'), |
725 | Class::MOP:::Attribute->new('$baz'), |
726 | ], |
727 | methods => { |
728 | calculate_bar => sub { ... }, |
729 | construct_baz => sub { ... } |
730 | } |
731 | )); |
732 | |
8b978dd5 |
733 | =head1 DESCRIPTION |
734 | |
fe122940 |
735 | This is the largest and currently most complex part of the Perl 5 |
736 | meta-object protocol. It controls the introspection and |
737 | manipulation of Perl 5 classes (and it can create them too). The |
738 | best way to understand what this module can do, is to read the |
739 | documentation for each of it's methods. |
740 | |
552e3d24 |
741 | =head1 METHODS |
742 | |
2eb717d5 |
743 | =head2 Self Introspection |
744 | |
745 | =over 4 |
746 | |
747 | =item B<meta> |
748 | |
fe122940 |
749 | This will return a B<Class::MOP::Class> instance which is related |
750 | to this class. Thereby allowing B<Class::MOP::Class> to actually |
751 | introspect itself. |
752 | |
753 | As with B<Class::MOP::Attribute>, B<Class::MOP> will actually |
754 | bootstrap this module by installing a number of attribute meta-objects |
755 | into it's metaclass. This will allow this class to reap all the benifits |
756 | of the MOP when subclassing it. |
2eb717d5 |
757 | |
587aca23 |
758 | =item B<get_all_metaclasses> |
759 | |
760 | This will return an hash of all the metaclass instances that have |
761 | been cached by B<Class::MOP::Class> keyed by the package name. |
762 | |
763 | =item B<get_all_metaclass_instances> |
764 | |
765 | This will return an array of all the metaclass instances that have |
766 | been cached by B<Class::MOP::Class>. |
767 | |
768 | =item B<get_all_metaclass_names> |
769 | |
770 | This will return an array of all the metaclass names that have |
771 | been cached by B<Class::MOP::Class>. |
772 | |
2eb717d5 |
773 | =back |
774 | |
552e3d24 |
775 | =head2 Class construction |
776 | |
a2e85e6c |
777 | These methods will handle creating B<Class::MOP::Class> objects, |
778 | which can be used to both create new classes, and analyze |
779 | pre-existing classes. |
552e3d24 |
780 | |
781 | This module will internally store references to all the instances |
782 | you create with these methods, so that they do not need to be |
783 | created any more than nessecary. Basically, they are singletons. |
784 | |
785 | =over 4 |
786 | |
787 | =item B<create ($package_name, ?$package_version, |
a2e85e6c |
788 | superclasses =E<gt> ?@superclasses, |
789 | methods =E<gt> ?%methods, |
790 | attributes =E<gt> ?%attributes)> |
552e3d24 |
791 | |
a2e85e6c |
792 | This returns a B<Class::MOP::Class> object, bringing the specified |
552e3d24 |
793 | C<$package_name> into existence and adding any of the |
794 | C<$package_version>, C<@superclasses>, C<%methods> and C<%attributes> |
795 | to it. |
796 | |
587aca23 |
797 | =item B<create_anon_class (superclasses =E<gt> ?@superclasses, |
798 | methods =E<gt> ?%methods, |
799 | attributes =E<gt> ?%attributes)> |
800 | |
801 | This will create an anonymous class, it works much like C<create> but |
802 | it does not need a C<$package_name>. Instead it will create a suitably |
803 | unique package name for you to stash things into. |
804 | |
66b3dded |
805 | =item B<initialize ($package_name, %options)> |
552e3d24 |
806 | |
a2e85e6c |
807 | This initializes and returns returns a B<Class::MOP::Class> object |
808 | for a given a C<$package_name>. |
809 | |
66b3dded |
810 | =item B<reinitialize ($package_name, %options)> |
811 | |
812 | This removes the old metaclass, and creates a new one in it's place. |
813 | Do B<not> use this unless you really know what you are doing, it could |
814 | very easily make a very large mess of your program. |
815 | |
651955fb |
816 | =item B<construct_class_instance (%options)> |
a2e85e6c |
817 | |
818 | This will construct an instance of B<Class::MOP::Class>, it is |
819 | here so that we can actually "tie the knot" for B<Class::MOP::Class> |
820 | to use C<construct_instance> once all the bootstrapping is done. This |
821 | method is used internally by C<initialize> and should never be called |
822 | from outside of that method really. |
552e3d24 |
823 | |
550d56db |
824 | =item B<check_metaclass_compatability> |
825 | |
826 | This method is called as the very last thing in the |
827 | C<construct_class_instance> method. This will check that the |
828 | metaclass you are creating is compatible with the metaclasses of all |
829 | your ancestors. For more inforamtion about metaclass compatibility |
830 | see the C<About Metaclass compatibility> section in L<Class::MOP>. |
831 | |
552e3d24 |
832 | =back |
833 | |
c9e77dbb |
834 | =head2 Object instance construction and cloning |
a2e85e6c |
835 | |
c9e77dbb |
836 | These methods are B<entirely optional>, it is up to you whether you want |
837 | to use them or not. |
552e3d24 |
838 | |
839 | =over 4 |
840 | |
2bab2be6 |
841 | =item B<instance_metaclass> |
842 | |
2d711cc8 |
843 | =item B<get_meta_instance> |
844 | |
5f3c057a |
845 | =item B<new_object (%params)> |
846 | |
847 | This is a convience method for creating a new object of the class, and |
848 | blessing it into the appropriate package as well. Ideally your class |
849 | would call a C<new> this method like so: |
850 | |
851 | sub MyClass::new { |
852 | my ($class, %param) = @_; |
853 | $class->meta->new_object(%params); |
854 | } |
855 | |
856 | Of course the ideal place for this would actually be in C<UNIVERSAL::> |
857 | but that is considered bad style, so we do not do that. |
858 | |
cbd9f942 |
859 | =item B<construct_instance (%params)> |
552e3d24 |
860 | |
c9e77dbb |
861 | This method is used to construct an instace structure suitable for |
862 | C<bless>-ing into your package of choice. It works in conjunction |
863 | with the Attribute protocol to collect all applicable attributes. |
864 | |
cbd9f942 |
865 | This will construct and instance using a HASH ref as storage |
552e3d24 |
866 | (currently only HASH references are supported). This will collect all |
a2e85e6c |
867 | the applicable attributes and layout out the fields in the HASH ref, |
868 | it will then initialize them using either use the corresponding key |
869 | in C<%params> or any default value or initializer found in the |
870 | attribute meta-object. |
727919c5 |
871 | |
5f3c057a |
872 | =item B<clone_object ($instance, %params)> |
873 | |
874 | This is a convience method for cloning an object instance, then |
19d4b5b8 |
875 | blessing it into the appropriate package. This method will call |
876 | C<clone_instance>, which performs a shallow copy of the object, |
877 | see that methods documentation for more details. Ideally your |
878 | class would call a C<clone> this method like so: |
5f3c057a |
879 | |
880 | sub MyClass::clone { |
881 | my ($self, %param) = @_; |
882 | $self->meta->clone_object($self, %params); |
883 | } |
884 | |
885 | Of course the ideal place for this would actually be in C<UNIVERSAL::> |
886 | but that is considered bad style, so we do not do that. |
887 | |
c9e77dbb |
888 | =item B<clone_instance($instance, %params)> |
889 | |
890 | This method is a compliment of C<construct_instance> (which means if |
19d4b5b8 |
891 | you override C<construct_instance>, you need to override this one too), |
892 | and clones the instance shallowly. |
a27ae83f |
893 | |
894 | The cloned structure returned is (like with C<construct_instance>) an |
895 | unC<bless>ed HASH reference, it is your responsibility to then bless |
896 | this cloned structure into the right class (which C<clone_object> will |
897 | do for you). |
c9e77dbb |
898 | |
19d4b5b8 |
899 | As of 0.11, this method will clone the C<$instance> structure shallowly, |
900 | as opposed to the deep cloning implemented in prior versions. After much |
901 | thought, research and discussion, I have decided that anything but basic |
902 | shallow cloning is outside the scope of the meta-object protocol. I |
903 | think Yuval "nothingmuch" Kogman put it best when he said that cloning |
904 | is too I<context-specific> to be part of the MOP. |
905 | |
552e3d24 |
906 | =back |
907 | |
908 | =head2 Informational |
909 | |
910 | =over 4 |
911 | |
912 | =item B<name> |
913 | |
a2e85e6c |
914 | This is a read-only attribute which returns the package name for the |
915 | given B<Class::MOP::Class> instance. |
552e3d24 |
916 | |
917 | =item B<version> |
918 | |
919 | This is a read-only attribute which returns the C<$VERSION> of the |
a2e85e6c |
920 | package for the given B<Class::MOP::Class> instance. |
552e3d24 |
921 | |
922 | =back |
923 | |
924 | =head2 Inheritance Relationships |
925 | |
926 | =over 4 |
927 | |
928 | =item B<superclasses (?@superclasses)> |
929 | |
930 | This is a read-write attribute which represents the superclass |
a2e85e6c |
931 | relationships of the class the B<Class::MOP::Class> instance is |
932 | associated with. Basically, it can get and set the C<@ISA> for you. |
552e3d24 |
933 | |
343203ee |
934 | B<NOTE:> |
935 | Perl will occasionally perform some C<@ISA> and method caching, if |
936 | you decide to change your superclass relationship at runtime (which |
937 | is quite insane and very much not recommened), then you should be |
938 | aware of this and the fact that this module does not make any |
939 | attempt to address this issue. |
940 | |
552e3d24 |
941 | =item B<class_precedence_list> |
942 | |
a2e85e6c |
943 | This computes the a list of all the class's ancestors in the same order |
944 | in which method dispatch will be done. This is similair to |
945 | what B<Class::ISA::super_path> does, but we don't remove duplicate names. |
552e3d24 |
946 | |
947 | =back |
948 | |
949 | =head2 Methods |
950 | |
951 | =over 4 |
952 | |
2e41896e |
953 | =item B<method_metaclass> |
954 | |
552e3d24 |
955 | =item B<add_method ($method_name, $method)> |
956 | |
957 | This will take a C<$method_name> and CODE reference to that |
a2e85e6c |
958 | C<$method> and install it into the class's package. |
552e3d24 |
959 | |
a2e85e6c |
960 | B<NOTE>: |
961 | This does absolutely nothing special to C<$method> |
552e3d24 |
962 | other than use B<Sub::Name> to make sure it is tagged with the |
963 | correct name, and therefore show up correctly in stack traces and |
964 | such. |
965 | |
663f8198 |
966 | =item B<alias_method ($method_name, $method)> |
967 | |
968 | This will take a C<$method_name> and CODE reference to that |
969 | C<$method> and alias the method into the class's package. |
970 | |
971 | B<NOTE>: |
972 | Unlike C<add_method>, this will B<not> try to name the |
973 | C<$method> using B<Sub::Name>, it only aliases the method in |
974 | the class's package. |
975 | |
552e3d24 |
976 | =item B<has_method ($method_name)> |
977 | |
a2e85e6c |
978 | This just provides a simple way to check if the class implements |
552e3d24 |
979 | a specific C<$method_name>. It will I<not> however, attempt to check |
a2e85e6c |
980 | if the class inherits the method (use C<UNIVERSAL::can> for that). |
552e3d24 |
981 | |
982 | This will correctly handle functions defined outside of the package |
983 | that use a fully qualified name (C<sub Package::name { ... }>). |
984 | |
985 | This will correctly handle functions renamed with B<Sub::Name> and |
986 | installed using the symbol tables. However, if you are naming the |
987 | subroutine outside of the package scope, you must use the fully |
988 | qualified name, including the package name, for C<has_method> to |
989 | correctly identify it. |
990 | |
991 | This will attempt to correctly ignore functions imported from other |
992 | packages using B<Exporter>. It breaks down if the function imported |
993 | is an C<__ANON__> sub (such as with C<use constant>), which very well |
994 | may be a valid method being applied to the class. |
995 | |
996 | In short, this method cannot always be trusted to determine if the |
997 | C<$method_name> is actually a method. However, it will DWIM about |
a2e85e6c |
998 | 90% of the time, so it's a small trade off I think. |
552e3d24 |
999 | |
1000 | =item B<get_method ($method_name)> |
1001 | |
1002 | This will return a CODE reference of the specified C<$method_name>, |
1003 | or return undef if that method does not exist. |
1004 | |
1005 | =item B<remove_method ($method_name)> |
1006 | |
a2e85e6c |
1007 | This will attempt to remove a given C<$method_name> from the class. |
552e3d24 |
1008 | It will return the CODE reference that it has removed, and will |
1009 | attempt to use B<Sub::Name> to clear the methods associated name. |
1010 | |
1011 | =item B<get_method_list> |
1012 | |
1013 | This will return a list of method names for all I<locally> defined |
1014 | methods. It does B<not> provide a list of all applicable methods, |
1015 | including any inherited ones. If you want a list of all applicable |
1016 | methods, use the C<compute_all_applicable_methods> method. |
1017 | |
1018 | =item B<compute_all_applicable_methods> |
1019 | |
a2e85e6c |
1020 | This will return a list of all the methods names this class will |
1021 | respond to, taking into account inheritance. The list will be a list of |
552e3d24 |
1022 | HASH references, each one containing the following information; method |
1023 | name, the name of the class in which the method lives and a CODE |
1024 | reference for the actual method. |
1025 | |
1026 | =item B<find_all_methods_by_name ($method_name)> |
1027 | |
1028 | This will traverse the inheritence hierarchy and locate all methods |
1029 | with a given C<$method_name>. Similar to |
1030 | C<compute_all_applicable_methods> it returns a list of HASH references |
1031 | with the following information; method name (which will always be the |
1032 | same as C<$method_name>), the name of the class in which the method |
1033 | lives and a CODE reference for the actual method. |
1034 | |
1035 | The list of methods produced is a distinct list, meaning there are no |
1036 | duplicates in it. This is especially useful for things like object |
1037 | initialization and destruction where you only want the method called |
1038 | once, and in the correct order. |
1039 | |
96ceced8 |
1040 | =item B<find_next_method_by_name ($method_name)> |
1041 | |
1042 | This will return the first method to match a given C<$method_name> in |
1043 | the superclasses, this is basically equivalent to calling |
1044 | C<SUPER::$method_name>, but it can be dispatched at runtime. |
1045 | |
552e3d24 |
1046 | =back |
1047 | |
a4258ffd |
1048 | =head2 Method Modifiers |
1049 | |
96ceced8 |
1050 | Method modifiers are a concept borrowed from CLOS, in which a method |
1051 | can be wrapped with I<before>, I<after> and I<around> method modifiers |
1052 | that will be called everytime the method is called. |
1053 | |
1054 | =head3 How method modifiers work? |
1055 | |
1056 | Method modifiers work by wrapping the original method and then replacing |
1057 | it in the classes symbol table. The wrappers will handle calling all the |
1058 | modifiers in the appropariate orders and preserving the calling context |
1059 | for the original method. |
1060 | |
1061 | Each method modifier serves a particular purpose, which may not be |
1062 | obvious to users of other method wrapping modules. To start with, the |
1063 | return values of I<before> and I<after> modifiers are ignored. This is |
1064 | because thier purpose is B<not> to filter the input and output of the |
1065 | primary method (this is done with an I<around> modifier). This may seem |
1066 | like an odd restriction to some, but doing this allows for simple code |
1067 | to be added at the begining or end of a method call without jeapordizing |
1068 | the normal functioning of the primary method or placing any extra |
1069 | responsibility on the code of the modifier. Of course if you have more |
1070 | complex needs, then use the I<around> modifier, which uses a variation |
1071 | of continutation passing style to allow for a high degree of flexibility. |
1072 | |
1073 | Before and around modifiers are called in last-defined-first-called order, |
1074 | while after modifiers are called in first-defined-first-called order. So |
1075 | the call tree might looks something like this: |
1076 | |
1077 | before 2 |
1078 | before 1 |
1079 | around 2 |
1080 | around 1 |
1081 | primary |
1082 | after 1 |
1083 | after 2 |
1084 | |
1085 | To see examples of using method modifiers, see the following examples |
1086 | included in the distribution; F<InstanceCountingClass>, F<Perl6Attribute>, |
1087 | F<AttributesWithHistory> and F<C3MethodDispatchOrder>. There is also a |
1088 | classic CLOS usage example in the test F<017_add_method_modifier.t>. |
1089 | |
1090 | =head3 What is the performance impact? |
1091 | |
1092 | Of course there is a performance cost associated with method modifiers, |
1093 | but we have made every effort to make that cost be directly proportional |
1094 | to the amount of modifier features you utilize. |
1095 | |
1096 | The wrapping method does it's best to B<only> do as much work as it |
1097 | absolutely needs to. In order to do this we have moved some of the |
1098 | performance costs to set-up time, where they are easier to amortize. |
1099 | |
1100 | All this said, my benchmarks have indicated the following: |
1101 | |
1102 | simple wrapper with no modifiers 100% slower |
1103 | simple wrapper with simple before modifier 400% slower |
1104 | simple wrapper with simple after modifier 450% slower |
1105 | simple wrapper with simple around modifier 500-550% slower |
1106 | simple wrapper with all 3 modifiers 1100% slower |
1107 | |
1108 | These numbers may seem daunting, but you must remember, every feature |
1109 | comes with some cost. To put things in perspective, just doing a simple |
1110 | C<AUTOLOAD> which does nothing but extract the name of the method called |
1111 | and return it costs about 400% over a normal method call. |
1112 | |
a4258ffd |
1113 | =over 4 |
1114 | |
1115 | =item B<add_before_method_modifier ($method_name, $code)> |
1116 | |
96ceced8 |
1117 | This will wrap the method at C<$method_name> and the supplied C<$code> |
1118 | will be passed the C<@_> arguments, and called before the original |
1119 | method is called. As specified above, the return value of the I<before> |
1120 | method modifiers is ignored, and it's ability to modify C<@_> is |
1121 | fairly limited. If you need to do either of these things, use an |
1122 | C<around> method modifier. |
1123 | |
a4258ffd |
1124 | =item B<add_after_method_modifier ($method_name, $code)> |
1125 | |
96ceced8 |
1126 | This will wrap the method at C<$method_name> so that the original |
1127 | method will be called, it's return values stashed, and then the |
1128 | supplied C<$code> will be passed the C<@_> arguments, and called. |
1129 | As specified above, the return value of the I<after> method |
1130 | modifiers is ignored, and it cannot modify the return values of |
1131 | the original method. If you need to do either of these things, use an |
1132 | C<around> method modifier. |
1133 | |
a4258ffd |
1134 | =item B<add_around_method_modifier ($method_name, $code)> |
1135 | |
96ceced8 |
1136 | This will wrap the method at C<$method_name> so that C<$code> |
1137 | will be called and passed the original method as an extra argument |
1138 | at the begining of the C<@_> argument list. This is a variation of |
1139 | continuation passing style, where the function prepended to C<@_> |
1140 | can be considered a continuation. It is up to C<$code> if it calls |
1141 | the original method or not, there is no restriction on what the |
1142 | C<$code> can or cannot do. |
1143 | |
a4258ffd |
1144 | =back |
1145 | |
552e3d24 |
1146 | =head2 Attributes |
1147 | |
1148 | It should be noted that since there is no one consistent way to define |
1149 | the attributes of a class in Perl 5. These methods can only work with |
1150 | the information given, and can not easily discover information on |
a2e85e6c |
1151 | their own. See L<Class::MOP::Attribute> for more details. |
552e3d24 |
1152 | |
1153 | =over 4 |
1154 | |
2e41896e |
1155 | =item B<attribute_metaclass> |
1156 | |
7b31baf4 |
1157 | =item B<get_attribute_map> |
1158 | |
552e3d24 |
1159 | =item B<add_attribute ($attribute_name, $attribute_meta_object)> |
1160 | |
a2e85e6c |
1161 | This stores a C<$attribute_meta_object> in the B<Class::MOP::Class> |
1162 | instance associated with the given class, and associates it with |
1163 | the C<$attribute_name>. Unlike methods, attributes within the MOP |
1164 | are stored as meta-information only. They will be used later to |
1165 | construct instances from (see C<construct_instance> above). |
552e3d24 |
1166 | More details about the attribute meta-objects can be found in the |
a2e85e6c |
1167 | L<Class::MOP::Attribute> or the L<Class::MOP/The Attribute protocol> |
1168 | section. |
1169 | |
1170 | It should be noted that any accessor, reader/writer or predicate |
1171 | methods which the C<$attribute_meta_object> has will be installed |
1172 | into the class at this time. |
552e3d24 |
1173 | |
1174 | =item B<has_attribute ($attribute_name)> |
1175 | |
a2e85e6c |
1176 | Checks to see if this class has an attribute by the name of |
552e3d24 |
1177 | C<$attribute_name> and returns a boolean. |
1178 | |
1179 | =item B<get_attribute ($attribute_name)> |
1180 | |
1181 | Returns the attribute meta-object associated with C<$attribute_name>, |
1182 | if none is found, it will return undef. |
1183 | |
1184 | =item B<remove_attribute ($attribute_name)> |
1185 | |
1186 | This will remove the attribute meta-object stored at |
1187 | C<$attribute_name>, then return the removed attribute meta-object. |
1188 | |
a2e85e6c |
1189 | B<NOTE:> |
1190 | Removing an attribute will only affect future instances of |
552e3d24 |
1191 | the class, it will not make any attempt to remove the attribute from |
1192 | any existing instances of the class. |
1193 | |
a2e85e6c |
1194 | It should be noted that any accessor, reader/writer or predicate |
1195 | methods which the attribute meta-object stored at C<$attribute_name> |
1196 | has will be removed from the class at this time. This B<will> make |
1197 | these attributes somewhat inaccessable in previously created |
1198 | instances. But if you are crazy enough to do this at runtime, then |
1199 | you are crazy enough to deal with something like this :). |
1200 | |
552e3d24 |
1201 | =item B<get_attribute_list> |
1202 | |
1203 | This returns a list of attribute names which are defined in the local |
1204 | class. If you want a list of all applicable attributes for a class, |
1205 | use the C<compute_all_applicable_attributes> method. |
1206 | |
1207 | =item B<compute_all_applicable_attributes> |
1208 | |
c9e77dbb |
1209 | This will traverse the inheritance heirachy and return a list of all |
1210 | the applicable attributes for this class. It does not construct a |
1211 | HASH reference like C<compute_all_applicable_methods> because all |
1212 | that same information is discoverable through the attribute |
1213 | meta-object itself. |
552e3d24 |
1214 | |
058c1cf5 |
1215 | =item B<find_attribute_by_name ($attr_name)> |
1216 | |
1217 | This method will traverse the inheritance heirachy and find the |
1218 | first attribute whose name matches C<$attr_name>, then return it. |
1219 | It will return undef if nothing is found. |
1220 | |
552e3d24 |
1221 | =back |
1222 | |
52e8a34c |
1223 | =head2 Package Variables |
1224 | |
1225 | Since Perl's classes are built atop the Perl package system, it is |
1226 | fairly common to use package scoped variables for things like static |
1227 | class variables. The following methods are convience methods for |
1228 | the creation and inspection of package scoped variables. |
1229 | |
1230 | =over 4 |
1231 | |
1232 | =item B<add_package_variable ($variable_name, ?$initial_value)> |
1233 | |
1234 | Given a C<$variable_name>, which must contain a leading sigil, this |
1235 | method will create that variable within the package which houses the |
1236 | class. It also takes an optional C<$initial_value>, which must be a |
1237 | reference of the same type as the sigil of the C<$variable_name> |
1238 | implies. |
1239 | |
1240 | =item B<get_package_variable ($variable_name)> |
1241 | |
1242 | This will return a reference to the package variable in |
1243 | C<$variable_name>. |
1244 | |
1245 | =item B<has_package_variable ($variable_name)> |
1246 | |
1247 | Returns true (C<1>) if there is a package variable defined for |
1248 | C<$variable_name>, and false (C<0>) otherwise. |
1249 | |
1250 | =item B<remove_package_variable ($variable_name)> |
1251 | |
1252 | This will attempt to remove the package variable at C<$variable_name>. |
1253 | |
1254 | =back |
1255 | |
8b978dd5 |
1256 | =head1 AUTHOR |
1257 | |
a2e85e6c |
1258 | Stevan Little E<lt>stevan@iinteractive.comE<gt> |
8b978dd5 |
1259 | |
1260 | =head1 COPYRIGHT AND LICENSE |
1261 | |
1262 | Copyright 2006 by Infinity Interactive, Inc. |
1263 | |
1264 | L<http://www.iinteractive.com> |
1265 | |
1266 | This library is free software; you can redistribute it and/or modify |
1267 | it under the same terms as Perl itself. |
1268 | |
798baea5 |
1269 | =cut |