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 | |
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, @_); |
50 | } |
51 | |
727919c5 |
52 | # NOTE: (meta-circularity) |
53 | # this is a special form of &construct_instance |
54 | # (see below), which is used to construct class |
1a7ebbb3 |
55 | # meta-object instances for any Class::MOP::* |
56 | # class. All other classes will use the more |
57 | # normal &construct_instance. |
727919c5 |
58 | sub construct_class_instance { |
351bd7d4 |
59 | my $class = shift; |
651955fb |
60 | my %options = @_; |
61 | my $package_name = $options{':package'}; |
727919c5 |
62 | (defined $package_name && $package_name) |
651955fb |
63 | || confess "You must pass a package name"; |
2d711cc8 |
64 | # NOTE: |
65 | # return the metaclass if we have it cached, |
66 | # and it is still defined (it has not been |
67 | # reaped by DESTROY yet, which can happen |
68 | # annoyingly enough during global destruction) |
2f6d5412 |
69 | return $METAS{$package_name} |
2d711cc8 |
70 | if exists $METAS{$package_name} && defined $METAS{$package_name}; |
1a7ebbb3 |
71 | $class = blessed($class) || $class; |
550d56db |
72 | # now create the metaclass |
73 | my $meta; |
1a7ebbb3 |
74 | if ($class =~ /^Class::MOP::/) { |
550d56db |
75 | $meta = bless { |
351bd7d4 |
76 | '$:package' => $package_name, |
77 | '%:attributes' => {}, |
550d56db |
78 | '$:attribute_metaclass' => $options{':attribute_metaclass'} || 'Class::MOP::Attribute', |
2bab2be6 |
79 | '$:method_metaclass' => $options{':method_metaclass'} || 'Class::MOP::Method', |
80 | '$:instance_metaclass' => $options{':instance_metaclass'} || 'Class::MOP::Instance', |
1a7ebbb3 |
81 | } => $class; |
82 | } |
83 | else { |
5f3c057a |
84 | # NOTE: |
85 | # it is safe to use meta here because |
86 | # class will always be a subclass of |
87 | # Class::MOP::Class, which defines meta |
550d56db |
88 | $meta = bless $class->meta->construct_instance(%options) => $class |
1a7ebbb3 |
89 | } |
550d56db |
90 | # and check the metaclass compatibility |
91 | $meta->check_metaclass_compatability(); |
92 | $METAS{$package_name} = $meta; |
93 | } |
94 | |
95 | sub check_metaclass_compatability { |
96 | my $self = shift; |
97 | |
98 | # this is always okay ... |
d82060fe |
99 | return if blessed($self) eq 'Class::MOP::Class' && |
100 | $self->instance_metaclass eq 'Class::MOP::Instance'; |
550d56db |
101 | |
102 | my @class_list = $self->class_precedence_list; |
103 | shift @class_list; # shift off $self->name |
104 | |
105 | foreach my $class_name (@class_list) { |
96ceced8 |
106 | my $meta = $METAS{$class_name} || next; |
550d56db |
107 | ($self->isa(blessed($meta))) |
108 | || confess $self->name . "->meta => (" . (blessed($self)) . ")" . |
109 | " is not compatible with the " . |
110 | $class_name . "->meta => (" . (blessed($meta)) . ")"; |
f7259199 |
111 | # NOTE: |
112 | # we also need to check that instance metaclasses |
113 | # are compatabile in the same the class. |
114 | ($self->instance_metaclass->isa($meta->instance_metaclass)) |
115 | || confess $self->name . "->meta => (" . ($self->instance_metaclass) . ")" . |
116 | " is not compatible with the " . |
117 | $class_name . "->meta => (" . ($meta->instance_metaclass) . ")"; |
550d56db |
118 | } |
fa16e528 |
119 | } |
f7259199 |
120 | } |
8b978dd5 |
121 | |
122 | sub create { |
123 | my ($class, $package_name, $package_version, %options) = @_; |
bfe4d0fc |
124 | (defined $package_name && $package_name) |
8b978dd5 |
125 | || confess "You must pass a package name"; |
126 | my $code = "package $package_name;"; |
127 | $code .= "\$$package_name\:\:VERSION = '$package_version';" |
128 | if defined $package_version; |
129 | eval $code; |
130 | confess "creation of $package_name failed : $@" if $@; |
bfe4d0fc |
131 | my $meta = $class->initialize($package_name); |
aa448b16 |
132 | |
133 | $meta->add_method('meta' => sub { |
134 | Class::MOP::Class->initialize(blessed($_[0]) || $_[0]); |
135 | }); |
136 | |
8b978dd5 |
137 | $meta->superclasses(@{$options{superclasses}}) |
138 | if exists $options{superclasses}; |
2eb717d5 |
139 | # NOTE: |
140 | # process attributes first, so that they can |
141 | # install accessors, but locally defined methods |
142 | # can then overwrite them. It is maybe a little odd, but |
143 | # I think this should be the order of things. |
144 | if (exists $options{attributes}) { |
cbd9f942 |
145 | foreach my $attr (@{$options{attributes}}) { |
146 | $meta->add_attribute($attr); |
2eb717d5 |
147 | } |
148 | } |
bfe4d0fc |
149 | if (exists $options{methods}) { |
150 | foreach my $method_name (keys %{$options{methods}}) { |
151 | $meta->add_method($method_name, $options{methods}->{$method_name}); |
152 | } |
2eb717d5 |
153 | } |
8b978dd5 |
154 | return $meta; |
155 | } |
156 | |
c3e7c446 |
157 | { |
4d154c08 |
158 | # NOTE: |
159 | # this should be sufficient, if you have a |
160 | # use case where it is not, write a test and |
161 | # I will change it. |
c3e7c446 |
162 | my $ANON_CLASS_SERIAL = 0; |
4d154c08 |
163 | |
c3e7c446 |
164 | sub create_anon_class { |
165 | my ($class, %options) = @_; |
166 | my $package_name = 'Class::MOP::Class::__ANON__::SERIAL::' . ++$ANON_CLASS_SERIAL; |
167 | return $class->create($package_name, '0.00', %options); |
168 | } |
587aca23 |
169 | } |
170 | |
7b31baf4 |
171 | ## Attribute readers |
172 | |
173 | # NOTE: |
174 | # all these attribute readers will be bootstrapped |
175 | # away in the Class::MOP bootstrap section |
176 | |
177 | sub name { $_[0]->{'$:package'} } |
178 | sub get_attribute_map { $_[0]->{'%:attributes'} } |
179 | sub attribute_metaclass { $_[0]->{'$:attribute_metaclass'} } |
180 | sub method_metaclass { $_[0]->{'$:method_metaclass'} } |
2bab2be6 |
181 | sub instance_metaclass { $_[0]->{'$:instance_metaclass'} } |
7b31baf4 |
182 | |
c9e77dbb |
183 | # Instance Construction & Cloning |
184 | |
5f3c057a |
185 | sub new_object { |
186 | my $class = shift; |
651955fb |
187 | # NOTE: |
188 | # we need to protect the integrity of the |
189 | # Class::MOP::Class singletons here, so we |
190 | # delegate this to &construct_class_instance |
191 | # which will deal with the singletons |
192 | return $class->construct_class_instance(@_) |
193 | if $class->name->isa('Class::MOP::Class'); |
24869f62 |
194 | return $class->construct_instance(@_); |
5f3c057a |
195 | } |
e16da3e6 |
196 | |
197 | sub construct_instance { |
cbd9f942 |
198 | my ($class, %params) = @_; |
0e76a376 |
199 | my $meta_instance = $class->get_meta_instance(); |
200 | my $instance = $meta_instance->create_instance(); |
c9e77dbb |
201 | foreach my $attr ($class->compute_all_applicable_attributes()) { |
f892c0f0 |
202 | $attr->initialize_instance_slot($meta_instance, $instance, \%params); |
cbd9f942 |
203 | } |
2d711cc8 |
204 | return $instance; |
205 | } |
206 | |
207 | sub get_meta_instance { |
208 | my $class = shift; |
052c2a1a |
209 | return $class->instance_metaclass->new( |
210 | $class, |
211 | $class->compute_all_applicable_attributes() |
212 | ); |
e16da3e6 |
213 | } |
214 | |
5f3c057a |
215 | sub clone_object { |
216 | my $class = shift; |
7b31baf4 |
217 | my $instance = shift; |
651955fb |
218 | (blessed($instance) && $instance->isa($class->name)) |
219 | || confess "You must pass an instance ($instance) of the metaclass (" . $class->name . ")"; |
220 | # NOTE: |
221 | # we need to protect the integrity of the |
222 | # Class::MOP::Class singletons here, they |
a740253a |
223 | # should not be cloned. |
651955fb |
224 | return $instance if $instance->isa('Class::MOP::Class'); |
f7259199 |
225 | $class->clone_instance($instance, @_); |
5f3c057a |
226 | } |
227 | |
c9e77dbb |
228 | sub clone_instance { |
651955fb |
229 | my ($class, $instance, %params) = @_; |
230 | (blessed($instance)) |
c9e77dbb |
231 | || confess "You can only clone instances, \$self is not a blessed instance"; |
f7259199 |
232 | my $meta_instance = $class->get_meta_instance(); |
233 | my $clone = $meta_instance->clone_instance($instance); |
234 | foreach my $key (%params) { |
235 | next unless $meta_instance->is_valid_slot($key); |
236 | $meta_instance->set_slot_value($clone, $key, $params{$key}); |
237 | } |
c9e77dbb |
238 | return $clone; |
239 | } |
240 | |
8b978dd5 |
241 | # Informational |
242 | |
7b31baf4 |
243 | # &name should be here too, but it is above |
244 | # because it gets bootstrapped away |
8b978dd5 |
245 | |
246 | sub version { |
247 | my $self = shift; |
96ceced8 |
248 | ${$self->get_package_variable('$VERSION')}; |
8b978dd5 |
249 | } |
250 | |
251 | # Inheritance |
252 | |
253 | sub superclasses { |
254 | my $self = shift; |
e7f732e4 |
255 | no strict 'refs'; |
8b978dd5 |
256 | if (@_) { |
257 | my @supers = @_; |
e7f732e4 |
258 | @{$self->name . '::ISA'} = @supers; |
d82060fe |
259 | # NOTE: |
260 | # we need to check the metaclass |
261 | # compatability here so that we can |
262 | # be sure that the superclass is |
263 | # not potentially creating an issues |
264 | # we don't know about |
265 | $self->check_metaclass_compatability(); |
8b978dd5 |
266 | } |
e7f732e4 |
267 | @{$self->name . '::ISA'}; |
8b978dd5 |
268 | } |
269 | |
270 | sub class_precedence_list { |
271 | my $self = shift; |
bfe4d0fc |
272 | # NOTE: |
273 | # We need to check for ciruclar inheirtance here. |
274 | # This will do nothing if all is well, and blow |
275 | # up otherwise. Yes, it's an ugly hack, better |
276 | # suggestions are welcome. |
93b4e576 |
277 | { ($self->name || return)->isa('This is a test for circular inheritance') } |
8c936afc |
278 | # ... and now back to our regularly scheduled program |
8b978dd5 |
279 | ( |
280 | $self->name, |
281 | map { |
f7259199 |
282 | $self->initialize($_)->class_precedence_list() |
8b978dd5 |
283 | } $self->superclasses() |
284 | ); |
285 | } |
286 | |
0882828e |
287 | ## Methods |
288 | |
289 | sub add_method { |
290 | my ($self, $method_name, $method) = @_; |
291 | (defined $method_name && $method_name) |
292 | || confess "You must define a method name"; |
a5eca695 |
293 | # use reftype here to allow for blessed subs ... |
ee5e71d4 |
294 | ('CODE' eq (reftype($method) || '')) |
0882828e |
295 | || confess "Your code block must be a CODE reference"; |
296 | my $full_method_name = ($self->name . '::' . $method_name); |
de19f115 |
297 | |
2d711cc8 |
298 | $method = $self->method_metaclass->wrap($method) unless blessed($method); |
299 | |
0882828e |
300 | no strict 'refs'; |
c9b8b7f9 |
301 | no warnings 'redefine'; |
22286063 |
302 | *{$full_method_name} = subname $full_method_name => $method; |
0882828e |
303 | } |
304 | |
a4258ffd |
305 | { |
2d711cc8 |
306 | my $fetch_and_prepare_method = sub { |
307 | my ($self, $method_name) = @_; |
308 | # fetch it locally |
309 | my $method = $self->get_method($method_name); |
310 | # if we dont have local ... |
311 | unless ($method) { |
312 | # make sure this method even exists ... |
313 | ($self->find_next_method_by_name($method_name)) |
314 | || confess "The method '$method_name' is not found in the inherience hierarchy for this class"; |
315 | # if so, then create a local which just |
316 | # calls the next applicable method ... |
317 | $self->add_method($method_name => sub { |
318 | $self->find_next_method_by_name($method_name)->(@_); |
319 | }); |
320 | $method = $self->get_method($method_name); |
321 | } |
322 | |
323 | # now make sure we wrap it properly |
324 | # (if it isnt already) |
325 | unless ($method->isa('Class::MOP::Method::Wrapped')) { |
326 | $method = Class::MOP::Method::Wrapped->wrap($method); |
327 | $self->add_method($method_name => $method); |
328 | } |
329 | return $method; |
330 | }; |
331 | |
332 | sub add_before_method_modifier { |
333 | my ($self, $method_name, $method_modifier) = @_; |
334 | (defined $method_name && $method_name) |
335 | || confess "You must pass in a method name"; |
336 | my $method = $fetch_and_prepare_method->($self, $method_name); |
337 | $method->add_before_modifier(subname ':before' => $method_modifier); |
338 | } |
339 | |
340 | sub add_after_method_modifier { |
341 | my ($self, $method_name, $method_modifier) = @_; |
342 | (defined $method_name && $method_name) |
343 | || confess "You must pass in a method name"; |
344 | my $method = $fetch_and_prepare_method->($self, $method_name); |
345 | $method->add_after_modifier(subname ':after' => $method_modifier); |
346 | } |
347 | |
348 | sub add_around_method_modifier { |
349 | my ($self, $method_name, $method_modifier) = @_; |
350 | (defined $method_name && $method_name) |
351 | || confess "You must pass in a method name"; |
352 | my $method = $fetch_and_prepare_method->($self, $method_name); |
353 | $method->add_around_modifier(subname ':around' => $method_modifier); |
354 | } |
a4258ffd |
355 | |
8c936afc |
356 | # NOTE: |
357 | # the methods above used to be named like this: |
358 | # ${pkg}::${method}:(before|after|around) |
359 | # but this proved problematic when using one modifier |
360 | # to wrap multiple methods (something which is likely |
361 | # to happen pretty regularly IMO). So instead of naming |
362 | # it like this, I have chosen to just name them purely |
363 | # with their modifier names, like so: |
364 | # :(before|after|around) |
365 | # The fact is that in a stack trace, it will be fairly |
366 | # evident from the context what method they are attached |
367 | # to, and so don't need the fully qualified name. |
ee5e71d4 |
368 | } |
369 | |
663f8198 |
370 | sub alias_method { |
371 | my ($self, $method_name, $method) = @_; |
372 | (defined $method_name && $method_name) |
373 | || confess "You must define a method name"; |
374 | # use reftype here to allow for blessed subs ... |
ee5e71d4 |
375 | ('CODE' eq (reftype($method) || '')) |
663f8198 |
376 | || confess "Your code block must be a CODE reference"; |
de19f115 |
377 | my $full_method_name = ($self->name . '::' . $method_name); |
378 | |
2d711cc8 |
379 | $method = $self->method_metaclass->wrap($method) unless blessed($method); |
663f8198 |
380 | |
381 | no strict 'refs'; |
382 | no warnings 'redefine'; |
383 | *{$full_method_name} = $method; |
384 | } |
385 | |
de19f115 |
386 | sub has_method { |
387 | my ($self, $method_name) = @_; |
388 | (defined $method_name && $method_name) |
389 | || confess "You must define a method name"; |
bfe4d0fc |
390 | |
de19f115 |
391 | my $sub_name = ($self->name . '::' . $method_name); |
0882828e |
392 | |
de19f115 |
393 | no strict 'refs'; |
394 | return 0 if !defined(&{$sub_name}); |
2d711cc8 |
395 | my $method = \&{$sub_name}; |
96ceced8 |
396 | return 0 if (svref_2object($method)->GV->STASH->NAME || '') ne $self->name && |
2d711cc8 |
397 | (svref_2object($method)->GV->NAME || '') ne '__ANON__'; |
398 | |
399 | # at this point we are relatively sure |
400 | # it is our method, so we bless/wrap it |
401 | $self->method_metaclass->wrap($method) unless blessed($method); |
de19f115 |
402 | return 1; |
0882828e |
403 | } |
404 | |
405 | sub get_method { |
c9b8b7f9 |
406 | my ($self, $method_name) = @_; |
0882828e |
407 | (defined $method_name && $method_name) |
408 | || confess "You must define a method name"; |
409 | |
2d711cc8 |
410 | return unless $self->has_method($method_name); |
de19f115 |
411 | |
0882828e |
412 | no strict 'refs'; |
de19f115 |
413 | return \&{$self->name . '::' . $method_name}; |
c9b8b7f9 |
414 | } |
415 | |
416 | sub remove_method { |
417 | my ($self, $method_name) = @_; |
418 | (defined $method_name && $method_name) |
419 | || confess "You must define a method name"; |
420 | |
421 | my $removed_method = $self->get_method($method_name); |
422 | |
423 | no strict 'refs'; |
424 | delete ${$self->name . '::'}{$method_name} |
425 | if defined $removed_method; |
426 | |
427 | return $removed_method; |
428 | } |
429 | |
430 | sub get_method_list { |
431 | my $self = shift; |
432 | no strict 'refs'; |
84e3c630 |
433 | grep { $self->has_method($_) } keys %{$self->name . '::'}; |
a5eca695 |
434 | } |
435 | |
436 | sub compute_all_applicable_methods { |
437 | my $self = shift; |
438 | my @methods; |
439 | # keep a record of what we have seen |
440 | # here, this will handle all the |
441 | # inheritence issues because we are |
442 | # using the &class_precedence_list |
443 | my (%seen_class, %seen_method); |
444 | foreach my $class ($self->class_precedence_list()) { |
445 | next if $seen_class{$class}; |
446 | $seen_class{$class}++; |
447 | # fetch the meta-class ... |
448 | my $meta = $self->initialize($class); |
449 | foreach my $method_name ($meta->get_method_list()) { |
450 | next if exists $seen_method{$method_name}; |
451 | $seen_method{$method_name}++; |
452 | push @methods => { |
453 | name => $method_name, |
454 | class => $class, |
455 | code => $meta->get_method($method_name) |
456 | }; |
457 | } |
458 | } |
459 | return @methods; |
460 | } |
461 | |
a5eca695 |
462 | sub find_all_methods_by_name { |
463 | my ($self, $method_name) = @_; |
464 | (defined $method_name && $method_name) |
465 | || confess "You must define a method name to find"; |
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; |
472 | foreach my $class ($self->class_precedence_list()) { |
473 | next if $seen_class{$class}; |
474 | $seen_class{$class}++; |
475 | # fetch the meta-class ... |
96ceced8 |
476 | my $meta = $self->initialize($class); |
a5eca695 |
477 | push @methods => { |
478 | name => $method_name, |
479 | class => $class, |
480 | code => $meta->get_method($method_name) |
481 | } if $meta->has_method($method_name); |
482 | } |
483 | return @methods; |
8b978dd5 |
484 | } |
485 | |
96ceced8 |
486 | sub find_next_method_by_name { |
487 | my ($self, $method_name) = @_; |
488 | (defined $method_name && $method_name) |
2d711cc8 |
489 | || confess "You must define a method name to find"; |
96ceced8 |
490 | # keep a record of what we have seen |
491 | # here, this will handle all the |
492 | # inheritence issues because we are |
493 | # using the &class_precedence_list |
494 | my %seen_class; |
2d711cc8 |
495 | my @cpl = $self->class_precedence_list(); |
496 | shift @cpl; # discard ourselves |
96ceced8 |
497 | foreach my $class (@cpl) { |
498 | next if $seen_class{$class}; |
499 | $seen_class{$class}++; |
500 | # fetch the meta-class ... |
501 | my $meta = $self->initialize($class); |
2d711cc8 |
502 | return $meta->get_method($method_name) |
503 | if $meta->has_method($method_name); |
96ceced8 |
504 | } |
2d711cc8 |
505 | return; |
96ceced8 |
506 | } |
507 | |
552e3d24 |
508 | ## Attributes |
509 | |
e16da3e6 |
510 | sub add_attribute { |
2e41896e |
511 | my $self = shift; |
512 | # either we have an attribute object already |
513 | # or we need to create one from the args provided |
514 | my $attribute = blessed($_[0]) ? $_[0] : $self->attribute_metaclass->new(@_); |
515 | # make sure it is derived from the correct type though |
516 | ($attribute->isa('Class::MOP::Attribute')) |
517 | || confess "Your attribute must be an instance of Class::MOP::Attribute (or a subclass)"; |
9ec169fe |
518 | $attribute->attach_to_class($self); |
2d711cc8 |
519 | $attribute->install_accessors(); |
291073fc |
520 | $self->get_attribute_map->{$attribute->name} = $attribute; |
9a1b7913 |
521 | |
522 | # FIXME |
523 | # in theory we have to tell everyone the slot structure may have changed |
e16da3e6 |
524 | } |
525 | |
526 | sub has_attribute { |
527 | my ($self, $attribute_name) = @_; |
528 | (defined $attribute_name && $attribute_name) |
529 | || confess "You must define an attribute name"; |
291073fc |
530 | exists $self->get_attribute_map->{$attribute_name} ? 1 : 0; |
e16da3e6 |
531 | } |
532 | |
533 | sub get_attribute { |
534 | my ($self, $attribute_name) = @_; |
535 | (defined $attribute_name && $attribute_name) |
536 | || confess "You must define an attribute name"; |
f7259199 |
537 | return $self->get_attribute_map->{$attribute_name} |
538 | if $self->has_attribute($attribute_name); |
22286063 |
539 | return; |
e16da3e6 |
540 | } |
541 | |
542 | sub remove_attribute { |
543 | my ($self, $attribute_name) = @_; |
544 | (defined $attribute_name && $attribute_name) |
545 | || confess "You must define an attribute name"; |
7b31baf4 |
546 | my $removed_attribute = $self->get_attribute_map->{$attribute_name}; |
22286063 |
547 | return unless defined $removed_attribute; |
548 | delete $self->get_attribute_map->{$attribute_name}; |
2d711cc8 |
549 | $removed_attribute->remove_accessors(); |
2d711cc8 |
550 | $removed_attribute->detach_from_class(); |
e16da3e6 |
551 | return $removed_attribute; |
552 | } |
553 | |
554 | sub get_attribute_list { |
555 | my $self = shift; |
f7259199 |
556 | keys %{$self->get_attribute_map}; |
e16da3e6 |
557 | } |
558 | |
559 | sub compute_all_applicable_attributes { |
560 | my $self = shift; |
561 | my @attrs; |
562 | # keep a record of what we have seen |
563 | # here, this will handle all the |
564 | # inheritence issues because we are |
565 | # using the &class_precedence_list |
566 | my (%seen_class, %seen_attr); |
567 | foreach my $class ($self->class_precedence_list()) { |
568 | next if $seen_class{$class}; |
569 | $seen_class{$class}++; |
570 | # fetch the meta-class ... |
f7259199 |
571 | my $meta = $self->initialize($class); |
e16da3e6 |
572 | foreach my $attr_name ($meta->get_attribute_list()) { |
573 | next if exists $seen_attr{$attr_name}; |
574 | $seen_attr{$attr_name}++; |
c9e77dbb |
575 | push @attrs => $meta->get_attribute($attr_name); |
e16da3e6 |
576 | } |
577 | } |
578 | return @attrs; |
579 | } |
2eb717d5 |
580 | |
058c1cf5 |
581 | sub find_attribute_by_name { |
582 | my ($self, $attr_name) = @_; |
583 | # keep a record of what we have seen |
584 | # here, this will handle all the |
585 | # inheritence issues because we are |
586 | # using the &class_precedence_list |
587 | my %seen_class; |
588 | foreach my $class ($self->class_precedence_list()) { |
589 | next if $seen_class{$class}; |
590 | $seen_class{$class}++; |
591 | # fetch the meta-class ... |
592 | my $meta = $self->initialize($class); |
593 | return $meta->get_attribute($attr_name) |
594 | if $meta->has_attribute($attr_name); |
595 | } |
596 | return; |
597 | } |
598 | |
52e8a34c |
599 | # Class attributes |
600 | |
601 | sub add_package_variable { |
602 | my ($self, $variable, $initial_value) = @_; |
603 | (defined $variable && $variable =~ /^[\$\@\%]/) |
604 | || confess "variable name does not have a sigil"; |
605 | |
606 | my ($sigil, $name) = ($variable =~ /^(.)(.*)$/); |
607 | if (defined $initial_value) { |
608 | no strict 'refs'; |
609 | *{$self->name . '::' . $name} = $initial_value; |
610 | } |
611 | else { |
39ec4f0c |
612 | my $e; |
613 | { |
614 | # NOTE: |
615 | # We HAVE to localize $@ or all |
616 | # hell breaks loose. It is not |
617 | # good, believe me, not good. |
618 | local $@; |
619 | eval $sigil . $self->name . '::' . $name; |
620 | $e = $@ if $@; |
621 | } |
622 | confess "Could not create package variable ($variable) because : $e" if $e; |
52e8a34c |
623 | } |
624 | } |
625 | |
626 | sub has_package_variable { |
627 | my ($self, $variable) = @_; |
628 | (defined $variable && $variable =~ /^[\$\@\%]/) |
629 | || confess "variable name does not have a sigil"; |
630 | my ($sigil, $name) = ($variable =~ /^(.)(.*)$/); |
631 | no strict 'refs'; |
632 | defined ${$self->name . '::'}{$name} ? 1 : 0; |
633 | } |
634 | |
635 | sub get_package_variable { |
636 | my ($self, $variable) = @_; |
637 | (defined $variable && $variable =~ /^[\$\@\%]/) |
638 | || confess "variable name does not have a sigil"; |
639 | my ($sigil, $name) = ($variable =~ /^(.)(.*)$/); |
39ec4f0c |
640 | my ($ref, $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 | $ref = eval '\\' . $sigil . $self->name . '::' . $name; |
648 | $e = $@ if $@; |
649 | } |
650 | confess "Could not get the package variable ($variable) because : $e" if $e; |
52e8a34c |
651 | # if we didn't die, then we can return it |
2d711cc8 |
652 | return $ref; |
52e8a34c |
653 | } |
654 | |
655 | sub remove_package_variable { |
656 | my ($self, $variable) = @_; |
657 | (defined $variable && $variable =~ /^[\$\@\%]/) |
658 | || confess "variable name does not have a sigil"; |
659 | my ($sigil, $name) = ($variable =~ /^(.)(.*)$/); |
660 | no strict 'refs'; |
661 | delete ${$self->name . '::'}{$name}; |
662 | } |
663 | |
8b978dd5 |
664 | 1; |
665 | |
666 | __END__ |
667 | |
668 | =pod |
669 | |
670 | =head1 NAME |
671 | |
672 | Class::MOP::Class - Class Meta Object |
673 | |
674 | =head1 SYNOPSIS |
675 | |
8c936afc |
676 | # assuming that class Foo |
677 | # has been defined, you can |
678 | |
fe122940 |
679 | # use this for introspection ... |
680 | |
fe122940 |
681 | # add a method to Foo ... |
682 | Foo->meta->add_method('bar' => sub { ... }) |
683 | |
684 | # get a list of all the classes searched |
685 | # the method dispatcher in the correct order |
686 | Foo->meta->class_precedence_list() |
687 | |
688 | # remove a method from Foo |
689 | Foo->meta->remove_method('bar'); |
690 | |
691 | # or use this to actually create classes ... |
692 | |
693 | Class::MOP::Class->create('Bar' => '0.01' => ( |
694 | superclasses => [ 'Foo' ], |
695 | attributes => [ |
696 | Class::MOP:::Attribute->new('$bar'), |
697 | Class::MOP:::Attribute->new('$baz'), |
698 | ], |
699 | methods => { |
700 | calculate_bar => sub { ... }, |
701 | construct_baz => sub { ... } |
702 | } |
703 | )); |
704 | |
8b978dd5 |
705 | =head1 DESCRIPTION |
706 | |
fe122940 |
707 | This is the largest and currently most complex part of the Perl 5 |
708 | meta-object protocol. It controls the introspection and |
709 | manipulation of Perl 5 classes (and it can create them too). The |
710 | best way to understand what this module can do, is to read the |
711 | documentation for each of it's methods. |
712 | |
552e3d24 |
713 | =head1 METHODS |
714 | |
2eb717d5 |
715 | =head2 Self Introspection |
716 | |
717 | =over 4 |
718 | |
719 | =item B<meta> |
720 | |
fe122940 |
721 | This will return a B<Class::MOP::Class> instance which is related |
722 | to this class. Thereby allowing B<Class::MOP::Class> to actually |
723 | introspect itself. |
724 | |
725 | As with B<Class::MOP::Attribute>, B<Class::MOP> will actually |
726 | bootstrap this module by installing a number of attribute meta-objects |
727 | into it's metaclass. This will allow this class to reap all the benifits |
728 | of the MOP when subclassing it. |
2eb717d5 |
729 | |
587aca23 |
730 | =item B<get_all_metaclasses> |
731 | |
732 | This will return an hash of all the metaclass instances that have |
733 | been cached by B<Class::MOP::Class> keyed by the package name. |
734 | |
735 | =item B<get_all_metaclass_instances> |
736 | |
737 | This will return an array of all the metaclass instances that have |
738 | been cached by B<Class::MOP::Class>. |
739 | |
740 | =item B<get_all_metaclass_names> |
741 | |
742 | This will return an array of all the metaclass names that have |
743 | been cached by B<Class::MOP::Class>. |
744 | |
2eb717d5 |
745 | =back |
746 | |
552e3d24 |
747 | =head2 Class construction |
748 | |
a2e85e6c |
749 | These methods will handle creating B<Class::MOP::Class> objects, |
750 | which can be used to both create new classes, and analyze |
751 | pre-existing classes. |
552e3d24 |
752 | |
753 | This module will internally store references to all the instances |
754 | you create with these methods, so that they do not need to be |
755 | created any more than nessecary. Basically, they are singletons. |
756 | |
757 | =over 4 |
758 | |
759 | =item B<create ($package_name, ?$package_version, |
a2e85e6c |
760 | superclasses =E<gt> ?@superclasses, |
761 | methods =E<gt> ?%methods, |
762 | attributes =E<gt> ?%attributes)> |
552e3d24 |
763 | |
a2e85e6c |
764 | This returns a B<Class::MOP::Class> object, bringing the specified |
552e3d24 |
765 | C<$package_name> into existence and adding any of the |
766 | C<$package_version>, C<@superclasses>, C<%methods> and C<%attributes> |
767 | to it. |
768 | |
587aca23 |
769 | =item B<create_anon_class (superclasses =E<gt> ?@superclasses, |
770 | methods =E<gt> ?%methods, |
771 | attributes =E<gt> ?%attributes)> |
772 | |
773 | This will create an anonymous class, it works much like C<create> but |
774 | it does not need a C<$package_name>. Instead it will create a suitably |
775 | unique package name for you to stash things into. |
776 | |
66b3dded |
777 | =item B<initialize ($package_name, %options)> |
552e3d24 |
778 | |
a2e85e6c |
779 | This initializes and returns returns a B<Class::MOP::Class> object |
780 | for a given a C<$package_name>. |
781 | |
66b3dded |
782 | =item B<reinitialize ($package_name, %options)> |
783 | |
784 | This removes the old metaclass, and creates a new one in it's place. |
785 | Do B<not> use this unless you really know what you are doing, it could |
786 | very easily make a very large mess of your program. |
787 | |
651955fb |
788 | =item B<construct_class_instance (%options)> |
a2e85e6c |
789 | |
790 | This will construct an instance of B<Class::MOP::Class>, it is |
791 | here so that we can actually "tie the knot" for B<Class::MOP::Class> |
792 | to use C<construct_instance> once all the bootstrapping is done. This |
793 | method is used internally by C<initialize> and should never be called |
794 | from outside of that method really. |
552e3d24 |
795 | |
550d56db |
796 | =item B<check_metaclass_compatability> |
797 | |
798 | This method is called as the very last thing in the |
799 | C<construct_class_instance> method. This will check that the |
800 | metaclass you are creating is compatible with the metaclasses of all |
801 | your ancestors. For more inforamtion about metaclass compatibility |
802 | see the C<About Metaclass compatibility> section in L<Class::MOP>. |
803 | |
552e3d24 |
804 | =back |
805 | |
c9e77dbb |
806 | =head2 Object instance construction and cloning |
a2e85e6c |
807 | |
c9e77dbb |
808 | These methods are B<entirely optional>, it is up to you whether you want |
809 | to use them or not. |
552e3d24 |
810 | |
811 | =over 4 |
812 | |
2bab2be6 |
813 | =item B<instance_metaclass> |
814 | |
2d711cc8 |
815 | =item B<get_meta_instance> |
816 | |
5f3c057a |
817 | =item B<new_object (%params)> |
818 | |
819 | This is a convience method for creating a new object of the class, and |
820 | blessing it into the appropriate package as well. Ideally your class |
821 | would call a C<new> this method like so: |
822 | |
823 | sub MyClass::new { |
824 | my ($class, %param) = @_; |
825 | $class->meta->new_object(%params); |
826 | } |
827 | |
828 | Of course the ideal place for this would actually be in C<UNIVERSAL::> |
829 | but that is considered bad style, so we do not do that. |
830 | |
cbd9f942 |
831 | =item B<construct_instance (%params)> |
552e3d24 |
832 | |
c9e77dbb |
833 | This method is used to construct an instace structure suitable for |
834 | C<bless>-ing into your package of choice. It works in conjunction |
835 | with the Attribute protocol to collect all applicable attributes. |
836 | |
cbd9f942 |
837 | This will construct and instance using a HASH ref as storage |
552e3d24 |
838 | (currently only HASH references are supported). This will collect all |
a2e85e6c |
839 | the applicable attributes and layout out the fields in the HASH ref, |
840 | it will then initialize them using either use the corresponding key |
841 | in C<%params> or any default value or initializer found in the |
842 | attribute meta-object. |
727919c5 |
843 | |
5f3c057a |
844 | =item B<clone_object ($instance, %params)> |
845 | |
846 | This is a convience method for cloning an object instance, then |
19d4b5b8 |
847 | blessing it into the appropriate package. This method will call |
848 | C<clone_instance>, which performs a shallow copy of the object, |
849 | see that methods documentation for more details. Ideally your |
850 | class would call a C<clone> this method like so: |
5f3c057a |
851 | |
852 | sub MyClass::clone { |
853 | my ($self, %param) = @_; |
854 | $self->meta->clone_object($self, %params); |
855 | } |
856 | |
857 | Of course the ideal place for this would actually be in C<UNIVERSAL::> |
858 | but that is considered bad style, so we do not do that. |
859 | |
c9e77dbb |
860 | =item B<clone_instance($instance, %params)> |
861 | |
862 | This method is a compliment of C<construct_instance> (which means if |
19d4b5b8 |
863 | you override C<construct_instance>, you need to override this one too), |
864 | and clones the instance shallowly. |
a27ae83f |
865 | |
866 | The cloned structure returned is (like with C<construct_instance>) an |
867 | unC<bless>ed HASH reference, it is your responsibility to then bless |
868 | this cloned structure into the right class (which C<clone_object> will |
869 | do for you). |
c9e77dbb |
870 | |
19d4b5b8 |
871 | As of 0.11, this method will clone the C<$instance> structure shallowly, |
872 | as opposed to the deep cloning implemented in prior versions. After much |
873 | thought, research and discussion, I have decided that anything but basic |
874 | shallow cloning is outside the scope of the meta-object protocol. I |
875 | think Yuval "nothingmuch" Kogman put it best when he said that cloning |
876 | is too I<context-specific> to be part of the MOP. |
877 | |
552e3d24 |
878 | =back |
879 | |
880 | =head2 Informational |
881 | |
882 | =over 4 |
883 | |
884 | =item B<name> |
885 | |
a2e85e6c |
886 | This is a read-only attribute which returns the package name for the |
887 | given B<Class::MOP::Class> instance. |
552e3d24 |
888 | |
889 | =item B<version> |
890 | |
891 | This is a read-only attribute which returns the C<$VERSION> of the |
a2e85e6c |
892 | package for the given B<Class::MOP::Class> instance. |
552e3d24 |
893 | |
894 | =back |
895 | |
896 | =head2 Inheritance Relationships |
897 | |
898 | =over 4 |
899 | |
900 | =item B<superclasses (?@superclasses)> |
901 | |
902 | This is a read-write attribute which represents the superclass |
a2e85e6c |
903 | relationships of the class the B<Class::MOP::Class> instance is |
904 | associated with. Basically, it can get and set the C<@ISA> for you. |
552e3d24 |
905 | |
343203ee |
906 | B<NOTE:> |
907 | Perl will occasionally perform some C<@ISA> and method caching, if |
908 | you decide to change your superclass relationship at runtime (which |
909 | is quite insane and very much not recommened), then you should be |
910 | aware of this and the fact that this module does not make any |
911 | attempt to address this issue. |
912 | |
552e3d24 |
913 | =item B<class_precedence_list> |
914 | |
a2e85e6c |
915 | This computes the a list of all the class's ancestors in the same order |
916 | in which method dispatch will be done. This is similair to |
917 | what B<Class::ISA::super_path> does, but we don't remove duplicate names. |
552e3d24 |
918 | |
919 | =back |
920 | |
921 | =head2 Methods |
922 | |
923 | =over 4 |
924 | |
2e41896e |
925 | =item B<method_metaclass> |
926 | |
552e3d24 |
927 | =item B<add_method ($method_name, $method)> |
928 | |
929 | This will take a C<$method_name> and CODE reference to that |
a2e85e6c |
930 | C<$method> and install it into the class's package. |
552e3d24 |
931 | |
a2e85e6c |
932 | B<NOTE>: |
933 | This does absolutely nothing special to C<$method> |
552e3d24 |
934 | other than use B<Sub::Name> to make sure it is tagged with the |
935 | correct name, and therefore show up correctly in stack traces and |
936 | such. |
937 | |
663f8198 |
938 | =item B<alias_method ($method_name, $method)> |
939 | |
940 | This will take a C<$method_name> and CODE reference to that |
941 | C<$method> and alias the method into the class's package. |
942 | |
943 | B<NOTE>: |
944 | Unlike C<add_method>, this will B<not> try to name the |
945 | C<$method> using B<Sub::Name>, it only aliases the method in |
946 | the class's package. |
947 | |
552e3d24 |
948 | =item B<has_method ($method_name)> |
949 | |
a2e85e6c |
950 | This just provides a simple way to check if the class implements |
552e3d24 |
951 | a specific C<$method_name>. It will I<not> however, attempt to check |
a2e85e6c |
952 | if the class inherits the method (use C<UNIVERSAL::can> for that). |
552e3d24 |
953 | |
954 | This will correctly handle functions defined outside of the package |
955 | that use a fully qualified name (C<sub Package::name { ... }>). |
956 | |
957 | This will correctly handle functions renamed with B<Sub::Name> and |
958 | installed using the symbol tables. However, if you are naming the |
959 | subroutine outside of the package scope, you must use the fully |
960 | qualified name, including the package name, for C<has_method> to |
961 | correctly identify it. |
962 | |
963 | This will attempt to correctly ignore functions imported from other |
964 | packages using B<Exporter>. It breaks down if the function imported |
965 | is an C<__ANON__> sub (such as with C<use constant>), which very well |
966 | may be a valid method being applied to the class. |
967 | |
968 | In short, this method cannot always be trusted to determine if the |
969 | C<$method_name> is actually a method. However, it will DWIM about |
a2e85e6c |
970 | 90% of the time, so it's a small trade off I think. |
552e3d24 |
971 | |
972 | =item B<get_method ($method_name)> |
973 | |
974 | This will return a CODE reference of the specified C<$method_name>, |
975 | or return undef if that method does not exist. |
976 | |
977 | =item B<remove_method ($method_name)> |
978 | |
a2e85e6c |
979 | This will attempt to remove a given C<$method_name> from the class. |
552e3d24 |
980 | It will return the CODE reference that it has removed, and will |
981 | attempt to use B<Sub::Name> to clear the methods associated name. |
982 | |
983 | =item B<get_method_list> |
984 | |
985 | This will return a list of method names for all I<locally> defined |
986 | methods. It does B<not> provide a list of all applicable methods, |
987 | including any inherited ones. If you want a list of all applicable |
988 | methods, use the C<compute_all_applicable_methods> method. |
989 | |
990 | =item B<compute_all_applicable_methods> |
991 | |
a2e85e6c |
992 | This will return a list of all the methods names this class will |
993 | respond to, taking into account inheritance. The list will be a list of |
552e3d24 |
994 | HASH references, each one containing the following information; method |
995 | name, the name of the class in which the method lives and a CODE |
996 | reference for the actual method. |
997 | |
998 | =item B<find_all_methods_by_name ($method_name)> |
999 | |
1000 | This will traverse the inheritence hierarchy and locate all methods |
1001 | with a given C<$method_name>. Similar to |
1002 | C<compute_all_applicable_methods> it returns a list of HASH references |
1003 | with the following information; method name (which will always be the |
1004 | same as C<$method_name>), the name of the class in which the method |
1005 | lives and a CODE reference for the actual method. |
1006 | |
1007 | The list of methods produced is a distinct list, meaning there are no |
1008 | duplicates in it. This is especially useful for things like object |
1009 | initialization and destruction where you only want the method called |
1010 | once, and in the correct order. |
1011 | |
96ceced8 |
1012 | =item B<find_next_method_by_name ($method_name)> |
1013 | |
1014 | This will return the first method to match a given C<$method_name> in |
1015 | the superclasses, this is basically equivalent to calling |
1016 | C<SUPER::$method_name>, but it can be dispatched at runtime. |
1017 | |
552e3d24 |
1018 | =back |
1019 | |
a4258ffd |
1020 | =head2 Method Modifiers |
1021 | |
96ceced8 |
1022 | Method modifiers are a concept borrowed from CLOS, in which a method |
1023 | can be wrapped with I<before>, I<after> and I<around> method modifiers |
1024 | that will be called everytime the method is called. |
1025 | |
1026 | =head3 How method modifiers work? |
1027 | |
1028 | Method modifiers work by wrapping the original method and then replacing |
1029 | it in the classes symbol table. The wrappers will handle calling all the |
1030 | modifiers in the appropariate orders and preserving the calling context |
1031 | for the original method. |
1032 | |
1033 | Each method modifier serves a particular purpose, which may not be |
1034 | obvious to users of other method wrapping modules. To start with, the |
1035 | return values of I<before> and I<after> modifiers are ignored. This is |
1036 | because thier purpose is B<not> to filter the input and output of the |
1037 | primary method (this is done with an I<around> modifier). This may seem |
1038 | like an odd restriction to some, but doing this allows for simple code |
1039 | to be added at the begining or end of a method call without jeapordizing |
1040 | the normal functioning of the primary method or placing any extra |
1041 | responsibility on the code of the modifier. Of course if you have more |
1042 | complex needs, then use the I<around> modifier, which uses a variation |
1043 | of continutation passing style to allow for a high degree of flexibility. |
1044 | |
1045 | Before and around modifiers are called in last-defined-first-called order, |
1046 | while after modifiers are called in first-defined-first-called order. So |
1047 | the call tree might looks something like this: |
1048 | |
1049 | before 2 |
1050 | before 1 |
1051 | around 2 |
1052 | around 1 |
1053 | primary |
1054 | after 1 |
1055 | after 2 |
1056 | |
1057 | To see examples of using method modifiers, see the following examples |
1058 | included in the distribution; F<InstanceCountingClass>, F<Perl6Attribute>, |
1059 | F<AttributesWithHistory> and F<C3MethodDispatchOrder>. There is also a |
1060 | classic CLOS usage example in the test F<017_add_method_modifier.t>. |
1061 | |
1062 | =head3 What is the performance impact? |
1063 | |
1064 | Of course there is a performance cost associated with method modifiers, |
1065 | but we have made every effort to make that cost be directly proportional |
1066 | to the amount of modifier features you utilize. |
1067 | |
1068 | The wrapping method does it's best to B<only> do as much work as it |
1069 | absolutely needs to. In order to do this we have moved some of the |
1070 | performance costs to set-up time, where they are easier to amortize. |
1071 | |
1072 | All this said, my benchmarks have indicated the following: |
1073 | |
1074 | simple wrapper with no modifiers 100% slower |
1075 | simple wrapper with simple before modifier 400% slower |
1076 | simple wrapper with simple after modifier 450% slower |
1077 | simple wrapper with simple around modifier 500-550% slower |
1078 | simple wrapper with all 3 modifiers 1100% slower |
1079 | |
1080 | These numbers may seem daunting, but you must remember, every feature |
1081 | comes with some cost. To put things in perspective, just doing a simple |
1082 | C<AUTOLOAD> which does nothing but extract the name of the method called |
1083 | and return it costs about 400% over a normal method call. |
1084 | |
a4258ffd |
1085 | =over 4 |
1086 | |
1087 | =item B<add_before_method_modifier ($method_name, $code)> |
1088 | |
96ceced8 |
1089 | This will wrap the method at C<$method_name> and the supplied C<$code> |
1090 | will be passed the C<@_> arguments, and called before the original |
1091 | method is called. As specified above, the return value of the I<before> |
1092 | method modifiers is ignored, and it's ability to modify C<@_> is |
1093 | fairly limited. If you need to do either of these things, use an |
1094 | C<around> method modifier. |
1095 | |
a4258ffd |
1096 | =item B<add_after_method_modifier ($method_name, $code)> |
1097 | |
96ceced8 |
1098 | This will wrap the method at C<$method_name> so that the original |
1099 | method will be called, it's return values stashed, and then the |
1100 | supplied C<$code> will be passed the C<@_> arguments, and called. |
1101 | As specified above, the return value of the I<after> method |
1102 | modifiers is ignored, and it cannot modify the return values of |
1103 | the original method. If you need to do either of these things, use an |
1104 | C<around> method modifier. |
1105 | |
a4258ffd |
1106 | =item B<add_around_method_modifier ($method_name, $code)> |
1107 | |
96ceced8 |
1108 | This will wrap the method at C<$method_name> so that C<$code> |
1109 | will be called and passed the original method as an extra argument |
1110 | at the begining of the C<@_> argument list. This is a variation of |
1111 | continuation passing style, where the function prepended to C<@_> |
1112 | can be considered a continuation. It is up to C<$code> if it calls |
1113 | the original method or not, there is no restriction on what the |
1114 | C<$code> can or cannot do. |
1115 | |
a4258ffd |
1116 | =back |
1117 | |
552e3d24 |
1118 | =head2 Attributes |
1119 | |
1120 | It should be noted that since there is no one consistent way to define |
1121 | the attributes of a class in Perl 5. These methods can only work with |
1122 | the information given, and can not easily discover information on |
a2e85e6c |
1123 | their own. See L<Class::MOP::Attribute> for more details. |
552e3d24 |
1124 | |
1125 | =over 4 |
1126 | |
2e41896e |
1127 | =item B<attribute_metaclass> |
1128 | |
7b31baf4 |
1129 | =item B<get_attribute_map> |
1130 | |
552e3d24 |
1131 | =item B<add_attribute ($attribute_name, $attribute_meta_object)> |
1132 | |
a2e85e6c |
1133 | This stores a C<$attribute_meta_object> in the B<Class::MOP::Class> |
1134 | instance associated with the given class, and associates it with |
1135 | the C<$attribute_name>. Unlike methods, attributes within the MOP |
1136 | are stored as meta-information only. They will be used later to |
1137 | construct instances from (see C<construct_instance> above). |
552e3d24 |
1138 | More details about the attribute meta-objects can be found in the |
a2e85e6c |
1139 | L<Class::MOP::Attribute> or the L<Class::MOP/The Attribute protocol> |
1140 | section. |
1141 | |
1142 | It should be noted that any accessor, reader/writer or predicate |
1143 | methods which the C<$attribute_meta_object> has will be installed |
1144 | into the class at this time. |
552e3d24 |
1145 | |
1146 | =item B<has_attribute ($attribute_name)> |
1147 | |
a2e85e6c |
1148 | Checks to see if this class has an attribute by the name of |
552e3d24 |
1149 | C<$attribute_name> and returns a boolean. |
1150 | |
1151 | =item B<get_attribute ($attribute_name)> |
1152 | |
1153 | Returns the attribute meta-object associated with C<$attribute_name>, |
1154 | if none is found, it will return undef. |
1155 | |
1156 | =item B<remove_attribute ($attribute_name)> |
1157 | |
1158 | This will remove the attribute meta-object stored at |
1159 | C<$attribute_name>, then return the removed attribute meta-object. |
1160 | |
a2e85e6c |
1161 | B<NOTE:> |
1162 | Removing an attribute will only affect future instances of |
552e3d24 |
1163 | the class, it will not make any attempt to remove the attribute from |
1164 | any existing instances of the class. |
1165 | |
a2e85e6c |
1166 | It should be noted that any accessor, reader/writer or predicate |
1167 | methods which the attribute meta-object stored at C<$attribute_name> |
1168 | has will be removed from the class at this time. This B<will> make |
1169 | these attributes somewhat inaccessable in previously created |
1170 | instances. But if you are crazy enough to do this at runtime, then |
1171 | you are crazy enough to deal with something like this :). |
1172 | |
552e3d24 |
1173 | =item B<get_attribute_list> |
1174 | |
1175 | This returns a list of attribute names which are defined in the local |
1176 | class. If you want a list of all applicable attributes for a class, |
1177 | use the C<compute_all_applicable_attributes> method. |
1178 | |
1179 | =item B<compute_all_applicable_attributes> |
1180 | |
c9e77dbb |
1181 | This will traverse the inheritance heirachy and return a list of all |
1182 | the applicable attributes for this class. It does not construct a |
1183 | HASH reference like C<compute_all_applicable_methods> because all |
1184 | that same information is discoverable through the attribute |
1185 | meta-object itself. |
552e3d24 |
1186 | |
058c1cf5 |
1187 | =item B<find_attribute_by_name ($attr_name)> |
1188 | |
1189 | This method will traverse the inheritance heirachy and find the |
1190 | first attribute whose name matches C<$attr_name>, then return it. |
1191 | It will return undef if nothing is found. |
1192 | |
552e3d24 |
1193 | =back |
1194 | |
52e8a34c |
1195 | =head2 Package Variables |
1196 | |
1197 | Since Perl's classes are built atop the Perl package system, it is |
1198 | fairly common to use package scoped variables for things like static |
1199 | class variables. The following methods are convience methods for |
1200 | the creation and inspection of package scoped variables. |
1201 | |
1202 | =over 4 |
1203 | |
1204 | =item B<add_package_variable ($variable_name, ?$initial_value)> |
1205 | |
1206 | Given a C<$variable_name>, which must contain a leading sigil, this |
1207 | method will create that variable within the package which houses the |
1208 | class. It also takes an optional C<$initial_value>, which must be a |
1209 | reference of the same type as the sigil of the C<$variable_name> |
1210 | implies. |
1211 | |
1212 | =item B<get_package_variable ($variable_name)> |
1213 | |
1214 | This will return a reference to the package variable in |
1215 | C<$variable_name>. |
1216 | |
1217 | =item B<has_package_variable ($variable_name)> |
1218 | |
1219 | Returns true (C<1>) if there is a package variable defined for |
1220 | C<$variable_name>, and false (C<0>) otherwise. |
1221 | |
1222 | =item B<remove_package_variable ($variable_name)> |
1223 | |
1224 | This will attempt to remove the package variable at C<$variable_name>. |
1225 | |
1226 | =back |
1227 | |
8b978dd5 |
1228 | =head1 AUTHOR |
1229 | |
a2e85e6c |
1230 | Stevan Little E<lt>stevan@iinteractive.comE<gt> |
8b978dd5 |
1231 | |
1232 | =head1 COPYRIGHT AND LICENSE |
1233 | |
1234 | Copyright 2006 by Infinity Interactive, Inc. |
1235 | |
1236 | L<http://www.iinteractive.com> |
1237 | |
1238 | This library is free software; you can redistribute it and/or modify |
1239 | it under the same terms as Perl itself. |
1240 | |
798baea5 |
1241 | =cut |