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 | |
bb8dacfa |
22 | #{ |
bfe4d0fc |
23 | # Metaclasses are singletons, so we cache them here. |
24 | # there is no need to worry about destruction though |
25 | # because they should die only when the program dies. |
26 | # After all, do package definitions even get reaped? |
587aca23 |
27 | my %METAS; |
28 | |
29 | # means of accessing all the metaclasses that have |
30 | # been initialized thus far (for mugwumps obj browser) |
31 | sub get_all_metaclasses { %METAS } |
32 | sub get_all_metaclass_instances { values %METAS } |
33 | sub get_all_metaclass_names { keys %METAS } |
651955fb |
34 | |
bfe4d0fc |
35 | sub initialize { |
351bd7d4 |
36 | my $class = shift; |
37 | my $package_name = shift; |
22286063 |
38 | (defined $package_name && $package_name && !blessed($package_name)) |
39 | || confess "You must pass a package name and it cannot be blessed"; |
651955fb |
40 | $class->construct_class_instance(':package' => $package_name, @_); |
727919c5 |
41 | } |
42 | |
43 | # NOTE: (meta-circularity) |
44 | # this is a special form of &construct_instance |
45 | # (see below), which is used to construct class |
1a7ebbb3 |
46 | # meta-object instances for any Class::MOP::* |
47 | # class. All other classes will use the more |
48 | # normal &construct_instance. |
727919c5 |
49 | sub construct_class_instance { |
351bd7d4 |
50 | my $class = shift; |
651955fb |
51 | my %options = @_; |
52 | my $package_name = $options{':package'}; |
727919c5 |
53 | (defined $package_name && $package_name) |
651955fb |
54 | || confess "You must pass a package name"; |
2f6d5412 |
55 | # NOTE: |
56 | # return the metaclass if we have it cached, |
57 | # and it is still defined (it has not been |
58 | # reaped by DESTROY yet, which can happen |
59 | # annoyingly enough during global destruction) |
60 | return $METAS{$package_name} |
61 | if exists $METAS{$package_name} && defined $METAS{$package_name}; |
1a7ebbb3 |
62 | $class = blessed($class) || $class; |
550d56db |
63 | # now create the metaclass |
64 | my $meta; |
1a7ebbb3 |
65 | if ($class =~ /^Class::MOP::/) { |
550d56db |
66 | $meta = bless { |
351bd7d4 |
67 | '$:package' => $package_name, |
68 | '%:attributes' => {}, |
550d56db |
69 | '$:attribute_metaclass' => $options{':attribute_metaclass'} || 'Class::MOP::Attribute', |
2bab2be6 |
70 | '$:method_metaclass' => $options{':method_metaclass'} || 'Class::MOP::Method', |
71 | '$:instance_metaclass' => $options{':instance_metaclass'} || 'Class::MOP::Instance', |
1a7ebbb3 |
72 | } => $class; |
73 | } |
74 | else { |
5f3c057a |
75 | # NOTE: |
76 | # it is safe to use meta here because |
77 | # class will always be a subclass of |
78 | # Class::MOP::Class, which defines meta |
550d56db |
79 | $meta = bless $class->meta->construct_instance(%options) => $class |
1a7ebbb3 |
80 | } |
550d56db |
81 | # and check the metaclass compatibility |
82 | $meta->check_metaclass_compatability(); |
83 | $METAS{$package_name} = $meta; |
84 | } |
85 | |
86 | sub check_metaclass_compatability { |
87 | my $self = shift; |
88 | |
89 | # this is always okay ... |
90 | return if blessed($self) eq 'Class::MOP::Class'; |
91 | |
92 | my @class_list = $self->class_precedence_list; |
93 | shift @class_list; # shift off $self->name |
94 | |
95 | foreach my $class_name (@class_list) { |
96ceced8 |
96 | my $meta = $METAS{$class_name} || next; |
550d56db |
97 | ($self->isa(blessed($meta))) |
98 | || confess $self->name . "->meta => (" . (blessed($self)) . ")" . |
99 | " is not compatible with the " . |
100 | $class_name . "->meta => (" . (blessed($meta)) . ")"; |
101 | } |
bfe4d0fc |
102 | } |
bb8dacfa |
103 | #} |
8b978dd5 |
104 | |
105 | sub create { |
106 | my ($class, $package_name, $package_version, %options) = @_; |
bfe4d0fc |
107 | (defined $package_name && $package_name) |
8b978dd5 |
108 | || confess "You must pass a package name"; |
109 | my $code = "package $package_name;"; |
110 | $code .= "\$$package_name\:\:VERSION = '$package_version';" |
111 | if defined $package_version; |
112 | eval $code; |
113 | confess "creation of $package_name failed : $@" if $@; |
bfe4d0fc |
114 | my $meta = $class->initialize($package_name); |
aa448b16 |
115 | |
116 | $meta->add_method('meta' => sub { |
117 | Class::MOP::Class->initialize(blessed($_[0]) || $_[0]); |
118 | }); |
119 | |
8b978dd5 |
120 | $meta->superclasses(@{$options{superclasses}}) |
121 | if exists $options{superclasses}; |
2eb717d5 |
122 | # NOTE: |
123 | # process attributes first, so that they can |
124 | # install accessors, but locally defined methods |
125 | # can then overwrite them. It is maybe a little odd, but |
126 | # I think this should be the order of things. |
127 | if (exists $options{attributes}) { |
cbd9f942 |
128 | foreach my $attr (@{$options{attributes}}) { |
129 | $meta->add_attribute($attr); |
2eb717d5 |
130 | } |
131 | } |
bfe4d0fc |
132 | if (exists $options{methods}) { |
133 | foreach my $method_name (keys %{$options{methods}}) { |
134 | $meta->add_method($method_name, $options{methods}->{$method_name}); |
135 | } |
2eb717d5 |
136 | } |
8b978dd5 |
137 | return $meta; |
138 | } |
139 | |
c3e7c446 |
140 | { |
4d154c08 |
141 | # NOTE: |
142 | # this should be sufficient, if you have a |
143 | # use case where it is not, write a test and |
144 | # I will change it. |
c3e7c446 |
145 | my $ANON_CLASS_SERIAL = 0; |
4d154c08 |
146 | |
c3e7c446 |
147 | sub create_anon_class { |
148 | my ($class, %options) = @_; |
149 | my $package_name = 'Class::MOP::Class::__ANON__::SERIAL::' . ++$ANON_CLASS_SERIAL; |
150 | return $class->create($package_name, '0.00', %options); |
151 | } |
587aca23 |
152 | } |
153 | |
7b31baf4 |
154 | ## Attribute readers |
155 | |
156 | # NOTE: |
157 | # all these attribute readers will be bootstrapped |
158 | # away in the Class::MOP bootstrap section |
159 | |
160 | sub name { $_[0]->{'$:package'} } |
161 | sub get_attribute_map { $_[0]->{'%:attributes'} } |
162 | sub attribute_metaclass { $_[0]->{'$:attribute_metaclass'} } |
163 | sub method_metaclass { $_[0]->{'$:method_metaclass'} } |
2bab2be6 |
164 | sub instance_metaclass { $_[0]->{'$:instance_metaclass'} } |
7b31baf4 |
165 | |
c9e77dbb |
166 | # Instance Construction & Cloning |
167 | |
5f3c057a |
168 | sub new_object { |
169 | my $class = shift; |
651955fb |
170 | # NOTE: |
171 | # we need to protect the integrity of the |
172 | # Class::MOP::Class singletons here, so we |
173 | # delegate this to &construct_class_instance |
174 | # which will deal with the singletons |
175 | return $class->construct_class_instance(@_) |
176 | if $class->name->isa('Class::MOP::Class'); |
24869f62 |
177 | return $class->construct_instance(@_); |
5f3c057a |
178 | } |
e16da3e6 |
179 | |
180 | sub construct_instance { |
cbd9f942 |
181 | my ($class, %params) = @_; |
2bab2be6 |
182 | my $meta_instance = $class->instance_metaclass->new($class); |
c9e77dbb |
183 | foreach my $attr ($class->compute_all_applicable_attributes()) { |
24869f62 |
184 | $attr->initialize_instance_slot($class, $meta_instance, \%params); |
cbd9f942 |
185 | } |
24869f62 |
186 | return $meta_instance->get_instance; |
e16da3e6 |
187 | } |
188 | |
5f3c057a |
189 | sub clone_object { |
190 | my $class = shift; |
7b31baf4 |
191 | my $instance = shift; |
651955fb |
192 | (blessed($instance) && $instance->isa($class->name)) |
193 | || confess "You must pass an instance ($instance) of the metaclass (" . $class->name . ")"; |
194 | # NOTE: |
195 | # we need to protect the integrity of the |
196 | # Class::MOP::Class singletons here, they |
a740253a |
197 | # should not be cloned. |
651955fb |
198 | return $instance if $instance->isa('Class::MOP::Class'); |
199 | bless $class->clone_instance($instance, @_) => blessed($instance); |
5f3c057a |
200 | } |
201 | |
c9e77dbb |
202 | sub clone_instance { |
651955fb |
203 | my ($class, $instance, %params) = @_; |
204 | (blessed($instance)) |
c9e77dbb |
205 | || confess "You can only clone instances, \$self is not a blessed instance"; |
19d4b5b8 |
206 | my $clone = { %$instance, %params }; |
c9e77dbb |
207 | return $clone; |
208 | } |
209 | |
8b978dd5 |
210 | # Informational |
211 | |
7b31baf4 |
212 | # &name should be here too, but it is above |
213 | # because it gets bootstrapped away |
8b978dd5 |
214 | |
215 | sub version { |
216 | my $self = shift; |
96ceced8 |
217 | ${$self->get_package_variable('$VERSION')}; |
8b978dd5 |
218 | } |
219 | |
220 | # Inheritance |
221 | |
222 | sub superclasses { |
223 | my $self = shift; |
e7f732e4 |
224 | no strict 'refs'; |
8b978dd5 |
225 | if (@_) { |
226 | my @supers = @_; |
e7f732e4 |
227 | @{$self->name . '::ISA'} = @supers; |
8b978dd5 |
228 | } |
e7f732e4 |
229 | @{$self->name . '::ISA'}; |
8b978dd5 |
230 | } |
231 | |
232 | sub class_precedence_list { |
233 | my $self = shift; |
bfe4d0fc |
234 | # NOTE: |
235 | # We need to check for ciruclar inheirtance here. |
236 | # This will do nothing if all is well, and blow |
237 | # up otherwise. Yes, it's an ugly hack, better |
238 | # suggestions are welcome. |
93b4e576 |
239 | { ($self->name || return)->isa('This is a test for circular inheritance') } |
8c936afc |
240 | # ... and now back to our regularly scheduled program |
8b978dd5 |
241 | ( |
242 | $self->name, |
243 | map { |
adfe5cc9 |
244 | # OPTIMIZATION NOTE: |
245 | # we grab the metaclass from the %METAS |
246 | # hash here to save the initialize() call |
247 | # if we can, but it is not always possible |
bb8dacfa |
248 | ($METAS{$_} || $self->initialize($_))->class_precedence_list() |
8b978dd5 |
249 | } $self->superclasses() |
250 | ); |
251 | } |
252 | |
0882828e |
253 | ## Methods |
254 | |
255 | sub add_method { |
256 | my ($self, $method_name, $method) = @_; |
257 | (defined $method_name && $method_name) |
258 | || confess "You must define a method name"; |
a5eca695 |
259 | # use reftype here to allow for blessed subs ... |
ee5e71d4 |
260 | ('CODE' eq (reftype($method) || '')) |
0882828e |
261 | || confess "Your code block must be a CODE reference"; |
262 | my $full_method_name = ($self->name . '::' . $method_name); |
de19f115 |
263 | |
a4258ffd |
264 | $method = $self->method_metaclass->wrap($method) unless blessed($method); |
de19f115 |
265 | |
0882828e |
266 | no strict 'refs'; |
c9b8b7f9 |
267 | no warnings 'redefine'; |
22286063 |
268 | *{$full_method_name} = subname $full_method_name => $method; |
0882828e |
269 | } |
270 | |
a4258ffd |
271 | { |
272 | my $fetch_and_prepare_method = sub { |
273 | my ($self, $method_name) = @_; |
274 | # fetch it locally |
275 | my $method = $self->get_method($method_name); |
276 | # if we dont have local ... |
277 | unless ($method) { |
96ceced8 |
278 | # make sure this method even exists ... |
279 | ($self->find_next_method_by_name($method_name)) |
280 | || confess "The method '$method_name' is not found in the inherience hierarchy for this class"; |
281 | # if so, then create a local which just |
282 | # calls the next applicable method ... |
283 | $self->add_method($method_name => sub { |
284 | $self->find_next_method_by_name($method_name)->(@_); |
285 | }); |
a4258ffd |
286 | $method = $self->get_method($method_name); |
287 | } |
288 | |
289 | # now make sure we wrap it properly |
290 | # (if it isnt already) |
291 | unless ($method->isa('Class::MOP::Method::Wrapped')) { |
292 | $method = Class::MOP::Method::Wrapped->wrap($method); |
293 | $self->add_method($method_name => $method); |
294 | } |
295 | return $method; |
296 | }; |
297 | |
298 | sub add_before_method_modifier { |
299 | my ($self, $method_name, $method_modifier) = @_; |
300 | (defined $method_name && $method_name) |
8c936afc |
301 | || confess "You must pass in a method name"; |
a4258ffd |
302 | my $method = $fetch_and_prepare_method->($self, $method_name); |
8c936afc |
303 | $method->add_before_modifier(subname ':before' => $method_modifier); |
a4258ffd |
304 | } |
ddc8edba |
305 | |
a4258ffd |
306 | sub add_after_method_modifier { |
307 | my ($self, $method_name, $method_modifier) = @_; |
308 | (defined $method_name && $method_name) |
8c936afc |
309 | || confess "You must pass in a method name"; |
a4258ffd |
310 | my $method = $fetch_and_prepare_method->($self, $method_name); |
8c936afc |
311 | $method->add_after_modifier(subname ':after' => $method_modifier); |
ddc8edba |
312 | } |
313 | |
a4258ffd |
314 | sub add_around_method_modifier { |
315 | my ($self, $method_name, $method_modifier) = @_; |
316 | (defined $method_name && $method_name) |
317 | || confess "You must pass in a method name"; |
a4258ffd |
318 | my $method = $fetch_and_prepare_method->($self, $method_name); |
8c936afc |
319 | $method->add_around_modifier(subname ':around' => $method_modifier); |
a4258ffd |
320 | } |
321 | |
8c936afc |
322 | # NOTE: |
323 | # the methods above used to be named like this: |
324 | # ${pkg}::${method}:(before|after|around) |
325 | # but this proved problematic when using one modifier |
326 | # to wrap multiple methods (something which is likely |
327 | # to happen pretty regularly IMO). So instead of naming |
328 | # it like this, I have chosen to just name them purely |
329 | # with their modifier names, like so: |
330 | # :(before|after|around) |
331 | # The fact is that in a stack trace, it will be fairly |
332 | # evident from the context what method they are attached |
333 | # to, and so don't need the fully qualified name. |
ee5e71d4 |
334 | } |
335 | |
663f8198 |
336 | sub alias_method { |
337 | my ($self, $method_name, $method) = @_; |
338 | (defined $method_name && $method_name) |
339 | || confess "You must define a method name"; |
340 | # use reftype here to allow for blessed subs ... |
ee5e71d4 |
341 | ('CODE' eq (reftype($method) || '')) |
663f8198 |
342 | || confess "Your code block must be a CODE reference"; |
de19f115 |
343 | my $full_method_name = ($self->name . '::' . $method_name); |
344 | |
a4258ffd |
345 | $method = $self->method_metaclass->wrap($method) unless blessed($method); |
663f8198 |
346 | |
347 | no strict 'refs'; |
348 | no warnings 'redefine'; |
349 | *{$full_method_name} = $method; |
350 | } |
351 | |
de19f115 |
352 | sub has_method { |
353 | my ($self, $method_name) = @_; |
354 | (defined $method_name && $method_name) |
355 | || confess "You must define a method name"; |
bfe4d0fc |
356 | |
de19f115 |
357 | my $sub_name = ($self->name . '::' . $method_name); |
0882828e |
358 | |
de19f115 |
359 | no strict 'refs'; |
360 | return 0 if !defined(&{$sub_name}); |
de19f115 |
361 | my $method = \&{$sub_name}; |
96ceced8 |
362 | return 0 if (svref_2object($method)->GV->STASH->NAME || '') ne $self->name && |
363 | (svref_2object($method)->GV->NAME || '') ne '__ANON__'; |
de19f115 |
364 | |
96ceced8 |
365 | # at this point we are relatively sure |
366 | # it is our method, so we bless/wrap it |
367 | $self->method_metaclass->wrap($method) unless blessed($method); |
de19f115 |
368 | return 1; |
0882828e |
369 | } |
370 | |
371 | sub get_method { |
c9b8b7f9 |
372 | my ($self, $method_name) = @_; |
0882828e |
373 | (defined $method_name && $method_name) |
374 | || confess "You must define a method name"; |
375 | |
de19f115 |
376 | return unless $self->has_method($method_name); |
377 | |
0882828e |
378 | no strict 'refs'; |
de19f115 |
379 | return \&{$self->name . '::' . $method_name}; |
c9b8b7f9 |
380 | } |
381 | |
382 | sub remove_method { |
383 | my ($self, $method_name) = @_; |
384 | (defined $method_name && $method_name) |
385 | || confess "You must define a method name"; |
386 | |
387 | my $removed_method = $self->get_method($method_name); |
388 | |
389 | no strict 'refs'; |
390 | delete ${$self->name . '::'}{$method_name} |
391 | if defined $removed_method; |
392 | |
393 | return $removed_method; |
394 | } |
395 | |
396 | sub get_method_list { |
397 | my $self = shift; |
398 | no strict 'refs'; |
a5eca695 |
399 | grep { $self->has_method($_) } %{$self->name . '::'}; |
400 | } |
401 | |
402 | sub compute_all_applicable_methods { |
403 | my $self = shift; |
404 | my @methods; |
405 | # keep a record of what we have seen |
406 | # here, this will handle all the |
407 | # inheritence issues because we are |
408 | # using the &class_precedence_list |
409 | my (%seen_class, %seen_method); |
410 | foreach my $class ($self->class_precedence_list()) { |
411 | next if $seen_class{$class}; |
412 | $seen_class{$class}++; |
413 | # fetch the meta-class ... |
414 | my $meta = $self->initialize($class); |
415 | foreach my $method_name ($meta->get_method_list()) { |
416 | next if exists $seen_method{$method_name}; |
417 | $seen_method{$method_name}++; |
418 | push @methods => { |
419 | name => $method_name, |
420 | class => $class, |
421 | code => $meta->get_method($method_name) |
422 | }; |
423 | } |
424 | } |
425 | return @methods; |
426 | } |
427 | |
a5eca695 |
428 | sub find_all_methods_by_name { |
429 | my ($self, $method_name) = @_; |
430 | (defined $method_name && $method_name) |
431 | || confess "You must define a method name to find"; |
432 | my @methods; |
433 | # keep a record of what we have seen |
434 | # here, this will handle all the |
435 | # inheritence issues because we are |
436 | # using the &class_precedence_list |
437 | my %seen_class; |
438 | foreach my $class ($self->class_precedence_list()) { |
439 | next if $seen_class{$class}; |
440 | $seen_class{$class}++; |
441 | # fetch the meta-class ... |
96ceced8 |
442 | my $meta = $self->initialize($class); |
a5eca695 |
443 | push @methods => { |
444 | name => $method_name, |
445 | class => $class, |
446 | code => $meta->get_method($method_name) |
447 | } if $meta->has_method($method_name); |
448 | } |
449 | return @methods; |
8b978dd5 |
450 | } |
451 | |
96ceced8 |
452 | sub find_next_method_by_name { |
453 | my ($self, $method_name) = @_; |
454 | (defined $method_name && $method_name) |
455 | || confess "You must define a method name to find"; |
456 | # keep a record of what we have seen |
457 | # here, this will handle all the |
458 | # inheritence issues because we are |
459 | # using the &class_precedence_list |
460 | my %seen_class; |
461 | my @cpl = $self->class_precedence_list(); |
462 | shift @cpl; # discard ourselves |
463 | foreach my $class (@cpl) { |
464 | next if $seen_class{$class}; |
465 | $seen_class{$class}++; |
466 | # fetch the meta-class ... |
467 | my $meta = $self->initialize($class); |
468 | return $meta->get_method($method_name) |
469 | if $meta->has_method($method_name); |
470 | } |
471 | return; |
472 | } |
473 | |
552e3d24 |
474 | ## Attributes |
475 | |
e16da3e6 |
476 | sub add_attribute { |
2e41896e |
477 | my $self = shift; |
478 | # either we have an attribute object already |
479 | # or we need to create one from the args provided |
480 | my $attribute = blessed($_[0]) ? $_[0] : $self->attribute_metaclass->new(@_); |
481 | # make sure it is derived from the correct type though |
482 | ($attribute->isa('Class::MOP::Attribute')) |
483 | || confess "Your attribute must be an instance of Class::MOP::Attribute (or a subclass)"; |
9ec169fe |
484 | $attribute->attach_to_class($self); |
485 | $attribute->install_accessors(); |
291073fc |
486 | $self->get_attribute_map->{$attribute->name} = $attribute; |
e16da3e6 |
487 | } |
488 | |
489 | sub has_attribute { |
490 | my ($self, $attribute_name) = @_; |
491 | (defined $attribute_name && $attribute_name) |
492 | || confess "You must define an attribute name"; |
291073fc |
493 | exists $self->get_attribute_map->{$attribute_name} ? 1 : 0; |
e16da3e6 |
494 | } |
495 | |
496 | sub get_attribute { |
497 | my ($self, $attribute_name) = @_; |
498 | (defined $attribute_name && $attribute_name) |
499 | || confess "You must define an attribute name"; |
bb8dacfa |
500 | # OPTIMIZATION NOTE: |
501 | # we used to say `if $self->has_attribute($attribute_name)` |
502 | # here, but since get_attribute is called so often, we |
503 | # eliminate the function call here |
504 | return $self->{'%:attributes'}->{$attribute_name} |
505 | if exists $self->{'%:attributes'}->{$attribute_name}; |
22286063 |
506 | return; |
e16da3e6 |
507 | } |
508 | |
509 | sub remove_attribute { |
510 | my ($self, $attribute_name) = @_; |
511 | (defined $attribute_name && $attribute_name) |
512 | || confess "You must define an attribute name"; |
7b31baf4 |
513 | my $removed_attribute = $self->get_attribute_map->{$attribute_name}; |
22286063 |
514 | return unless defined $removed_attribute; |
515 | delete $self->get_attribute_map->{$attribute_name}; |
9ec169fe |
516 | $removed_attribute->remove_accessors(); |
517 | $removed_attribute->detach_from_class(); |
e16da3e6 |
518 | return $removed_attribute; |
519 | } |
520 | |
521 | sub get_attribute_list { |
522 | my $self = shift; |
bb8dacfa |
523 | # OPTIMIZATION NOTE: |
524 | # We don't use get_attribute_map here because |
525 | # we ask for the attribute list quite often |
526 | # in compute_all_applicable_attributes, so |
527 | # eliminating the function call helps |
528 | keys %{$self->{'%:attributes'}}; |
e16da3e6 |
529 | } |
530 | |
531 | sub compute_all_applicable_attributes { |
532 | my $self = shift; |
533 | my @attrs; |
534 | # keep a record of what we have seen |
535 | # here, this will handle all the |
536 | # inheritence issues because we are |
537 | # using the &class_precedence_list |
538 | my (%seen_class, %seen_attr); |
539 | foreach my $class ($self->class_precedence_list()) { |
540 | next if $seen_class{$class}; |
541 | $seen_class{$class}++; |
542 | # fetch the meta-class ... |
adfe5cc9 |
543 | # OPTIMIZATION NOTE: |
544 | # we grab the metaclass from the %METAS |
545 | # hash here to save the initialize() call |
546 | my $meta = $METAS{$class}; |
e16da3e6 |
547 | foreach my $attr_name ($meta->get_attribute_list()) { |
548 | next if exists $seen_attr{$attr_name}; |
549 | $seen_attr{$attr_name}++; |
c9e77dbb |
550 | push @attrs => $meta->get_attribute($attr_name); |
e16da3e6 |
551 | } |
552 | } |
553 | return @attrs; |
554 | } |
2eb717d5 |
555 | |
058c1cf5 |
556 | sub find_attribute_by_name { |
557 | my ($self, $attr_name) = @_; |
558 | # keep a record of what we have seen |
559 | # here, this will handle all the |
560 | # inheritence issues because we are |
561 | # using the &class_precedence_list |
562 | my %seen_class; |
563 | foreach my $class ($self->class_precedence_list()) { |
564 | next if $seen_class{$class}; |
565 | $seen_class{$class}++; |
566 | # fetch the meta-class ... |
567 | my $meta = $self->initialize($class); |
568 | return $meta->get_attribute($attr_name) |
569 | if $meta->has_attribute($attr_name); |
570 | } |
571 | return; |
572 | } |
573 | |
52e8a34c |
574 | # Class attributes |
575 | |
576 | sub add_package_variable { |
577 | my ($self, $variable, $initial_value) = @_; |
578 | (defined $variable && $variable =~ /^[\$\@\%]/) |
579 | || confess "variable name does not have a sigil"; |
580 | |
581 | my ($sigil, $name) = ($variable =~ /^(.)(.*)$/); |
582 | if (defined $initial_value) { |
583 | no strict 'refs'; |
584 | *{$self->name . '::' . $name} = $initial_value; |
585 | } |
586 | else { |
39ec4f0c |
587 | my $e; |
588 | { |
589 | # NOTE: |
590 | # We HAVE to localize $@ or all |
591 | # hell breaks loose. It is not |
592 | # good, believe me, not good. |
593 | local $@; |
594 | eval $sigil . $self->name . '::' . $name; |
595 | $e = $@ if $@; |
596 | } |
597 | confess "Could not create package variable ($variable) because : $e" if $e; |
52e8a34c |
598 | } |
599 | } |
600 | |
601 | sub has_package_variable { |
602 | my ($self, $variable) = @_; |
603 | (defined $variable && $variable =~ /^[\$\@\%]/) |
604 | || confess "variable name does not have a sigil"; |
605 | my ($sigil, $name) = ($variable =~ /^(.)(.*)$/); |
606 | no strict 'refs'; |
607 | defined ${$self->name . '::'}{$name} ? 1 : 0; |
608 | } |
609 | |
610 | sub get_package_variable { |
611 | my ($self, $variable) = @_; |
612 | (defined $variable && $variable =~ /^[\$\@\%]/) |
613 | || confess "variable name does not have a sigil"; |
614 | my ($sigil, $name) = ($variable =~ /^(.)(.*)$/); |
39ec4f0c |
615 | my ($ref, $e); |
616 | { |
617 | # NOTE: |
618 | # We HAVE to localize $@ or all |
619 | # hell breaks loose. It is not |
620 | # good, believe me, not good. |
621 | local $@; |
622 | $ref = eval '\\' . $sigil . $self->name . '::' . $name; |
623 | $e = $@ if $@; |
624 | } |
625 | confess "Could not get the package variable ($variable) because : $e" if $e; |
52e8a34c |
626 | # if we didn't die, then we can return it |
18697ac8 |
627 | return $ref; |
52e8a34c |
628 | } |
629 | |
630 | sub remove_package_variable { |
631 | my ($self, $variable) = @_; |
632 | (defined $variable && $variable =~ /^[\$\@\%]/) |
633 | || confess "variable name does not have a sigil"; |
634 | my ($sigil, $name) = ($variable =~ /^(.)(.*)$/); |
635 | no strict 'refs'; |
636 | delete ${$self->name . '::'}{$name}; |
637 | } |
638 | |
8b978dd5 |
639 | 1; |
640 | |
641 | __END__ |
642 | |
643 | =pod |
644 | |
645 | =head1 NAME |
646 | |
647 | Class::MOP::Class - Class Meta Object |
648 | |
649 | =head1 SYNOPSIS |
650 | |
8c936afc |
651 | # assuming that class Foo |
652 | # has been defined, you can |
653 | |
fe122940 |
654 | # use this for introspection ... |
655 | |
fe122940 |
656 | # add a method to Foo ... |
657 | Foo->meta->add_method('bar' => sub { ... }) |
658 | |
659 | # get a list of all the classes searched |
660 | # the method dispatcher in the correct order |
661 | Foo->meta->class_precedence_list() |
662 | |
663 | # remove a method from Foo |
664 | Foo->meta->remove_method('bar'); |
665 | |
666 | # or use this to actually create classes ... |
667 | |
668 | Class::MOP::Class->create('Bar' => '0.01' => ( |
669 | superclasses => [ 'Foo' ], |
670 | attributes => [ |
671 | Class::MOP:::Attribute->new('$bar'), |
672 | Class::MOP:::Attribute->new('$baz'), |
673 | ], |
674 | methods => { |
675 | calculate_bar => sub { ... }, |
676 | construct_baz => sub { ... } |
677 | } |
678 | )); |
679 | |
8b978dd5 |
680 | =head1 DESCRIPTION |
681 | |
fe122940 |
682 | This is the largest and currently most complex part of the Perl 5 |
683 | meta-object protocol. It controls the introspection and |
684 | manipulation of Perl 5 classes (and it can create them too). The |
685 | best way to understand what this module can do, is to read the |
686 | documentation for each of it's methods. |
687 | |
552e3d24 |
688 | =head1 METHODS |
689 | |
2eb717d5 |
690 | =head2 Self Introspection |
691 | |
692 | =over 4 |
693 | |
694 | =item B<meta> |
695 | |
fe122940 |
696 | This will return a B<Class::MOP::Class> instance which is related |
697 | to this class. Thereby allowing B<Class::MOP::Class> to actually |
698 | introspect itself. |
699 | |
700 | As with B<Class::MOP::Attribute>, B<Class::MOP> will actually |
701 | bootstrap this module by installing a number of attribute meta-objects |
702 | into it's metaclass. This will allow this class to reap all the benifits |
703 | of the MOP when subclassing it. |
2eb717d5 |
704 | |
587aca23 |
705 | =item B<get_all_metaclasses> |
706 | |
707 | This will return an hash of all the metaclass instances that have |
708 | been cached by B<Class::MOP::Class> keyed by the package name. |
709 | |
710 | =item B<get_all_metaclass_instances> |
711 | |
712 | This will return an array of all the metaclass instances that have |
713 | been cached by B<Class::MOP::Class>. |
714 | |
715 | =item B<get_all_metaclass_names> |
716 | |
717 | This will return an array of all the metaclass names that have |
718 | been cached by B<Class::MOP::Class>. |
719 | |
2eb717d5 |
720 | =back |
721 | |
552e3d24 |
722 | =head2 Class construction |
723 | |
a2e85e6c |
724 | These methods will handle creating B<Class::MOP::Class> objects, |
725 | which can be used to both create new classes, and analyze |
726 | pre-existing classes. |
552e3d24 |
727 | |
728 | This module will internally store references to all the instances |
729 | you create with these methods, so that they do not need to be |
730 | created any more than nessecary. Basically, they are singletons. |
731 | |
732 | =over 4 |
733 | |
734 | =item B<create ($package_name, ?$package_version, |
a2e85e6c |
735 | superclasses =E<gt> ?@superclasses, |
736 | methods =E<gt> ?%methods, |
737 | attributes =E<gt> ?%attributes)> |
552e3d24 |
738 | |
a2e85e6c |
739 | This returns a B<Class::MOP::Class> object, bringing the specified |
552e3d24 |
740 | C<$package_name> into existence and adding any of the |
741 | C<$package_version>, C<@superclasses>, C<%methods> and C<%attributes> |
742 | to it. |
743 | |
587aca23 |
744 | =item B<create_anon_class (superclasses =E<gt> ?@superclasses, |
745 | methods =E<gt> ?%methods, |
746 | attributes =E<gt> ?%attributes)> |
747 | |
748 | This will create an anonymous class, it works much like C<create> but |
749 | it does not need a C<$package_name>. Instead it will create a suitably |
750 | unique package name for you to stash things into. |
751 | |
552e3d24 |
752 | =item B<initialize ($package_name)> |
753 | |
a2e85e6c |
754 | This initializes and returns returns a B<Class::MOP::Class> object |
755 | for a given a C<$package_name>. |
756 | |
651955fb |
757 | =item B<construct_class_instance (%options)> |
a2e85e6c |
758 | |
759 | This will construct an instance of B<Class::MOP::Class>, it is |
760 | here so that we can actually "tie the knot" for B<Class::MOP::Class> |
761 | to use C<construct_instance> once all the bootstrapping is done. This |
762 | method is used internally by C<initialize> and should never be called |
763 | from outside of that method really. |
552e3d24 |
764 | |
550d56db |
765 | =item B<check_metaclass_compatability> |
766 | |
767 | This method is called as the very last thing in the |
768 | C<construct_class_instance> method. This will check that the |
769 | metaclass you are creating is compatible with the metaclasses of all |
770 | your ancestors. For more inforamtion about metaclass compatibility |
771 | see the C<About Metaclass compatibility> section in L<Class::MOP>. |
772 | |
552e3d24 |
773 | =back |
774 | |
c9e77dbb |
775 | =head2 Object instance construction and cloning |
a2e85e6c |
776 | |
c9e77dbb |
777 | These methods are B<entirely optional>, it is up to you whether you want |
778 | to use them or not. |
552e3d24 |
779 | |
780 | =over 4 |
781 | |
2bab2be6 |
782 | =item B<instance_metaclass> |
783 | |
5f3c057a |
784 | =item B<new_object (%params)> |
785 | |
786 | This is a convience method for creating a new object of the class, and |
787 | blessing it into the appropriate package as well. Ideally your class |
788 | would call a C<new> this method like so: |
789 | |
790 | sub MyClass::new { |
791 | my ($class, %param) = @_; |
792 | $class->meta->new_object(%params); |
793 | } |
794 | |
795 | Of course the ideal place for this would actually be in C<UNIVERSAL::> |
796 | but that is considered bad style, so we do not do that. |
797 | |
cbd9f942 |
798 | =item B<construct_instance (%params)> |
552e3d24 |
799 | |
c9e77dbb |
800 | This method is used to construct an instace structure suitable for |
801 | C<bless>-ing into your package of choice. It works in conjunction |
802 | with the Attribute protocol to collect all applicable attributes. |
803 | |
cbd9f942 |
804 | This will construct and instance using a HASH ref as storage |
552e3d24 |
805 | (currently only HASH references are supported). This will collect all |
a2e85e6c |
806 | the applicable attributes and layout out the fields in the HASH ref, |
807 | it will then initialize them using either use the corresponding key |
808 | in C<%params> or any default value or initializer found in the |
809 | attribute meta-object. |
727919c5 |
810 | |
5f3c057a |
811 | =item B<clone_object ($instance, %params)> |
812 | |
813 | This is a convience method for cloning an object instance, then |
19d4b5b8 |
814 | blessing it into the appropriate package. This method will call |
815 | C<clone_instance>, which performs a shallow copy of the object, |
816 | see that methods documentation for more details. Ideally your |
817 | class would call a C<clone> this method like so: |
5f3c057a |
818 | |
819 | sub MyClass::clone { |
820 | my ($self, %param) = @_; |
821 | $self->meta->clone_object($self, %params); |
822 | } |
823 | |
824 | Of course the ideal place for this would actually be in C<UNIVERSAL::> |
825 | but that is considered bad style, so we do not do that. |
826 | |
c9e77dbb |
827 | =item B<clone_instance($instance, %params)> |
828 | |
829 | This method is a compliment of C<construct_instance> (which means if |
19d4b5b8 |
830 | you override C<construct_instance>, you need to override this one too), |
831 | and clones the instance shallowly. |
a27ae83f |
832 | |
833 | The cloned structure returned is (like with C<construct_instance>) an |
834 | unC<bless>ed HASH reference, it is your responsibility to then bless |
835 | this cloned structure into the right class (which C<clone_object> will |
836 | do for you). |
c9e77dbb |
837 | |
19d4b5b8 |
838 | As of 0.11, this method will clone the C<$instance> structure shallowly, |
839 | as opposed to the deep cloning implemented in prior versions. After much |
840 | thought, research and discussion, I have decided that anything but basic |
841 | shallow cloning is outside the scope of the meta-object protocol. I |
842 | think Yuval "nothingmuch" Kogman put it best when he said that cloning |
843 | is too I<context-specific> to be part of the MOP. |
844 | |
552e3d24 |
845 | =back |
846 | |
847 | =head2 Informational |
848 | |
849 | =over 4 |
850 | |
851 | =item B<name> |
852 | |
a2e85e6c |
853 | This is a read-only attribute which returns the package name for the |
854 | given B<Class::MOP::Class> instance. |
552e3d24 |
855 | |
856 | =item B<version> |
857 | |
858 | This is a read-only attribute which returns the C<$VERSION> of the |
a2e85e6c |
859 | package for the given B<Class::MOP::Class> instance. |
552e3d24 |
860 | |
861 | =back |
862 | |
863 | =head2 Inheritance Relationships |
864 | |
865 | =over 4 |
866 | |
867 | =item B<superclasses (?@superclasses)> |
868 | |
869 | This is a read-write attribute which represents the superclass |
a2e85e6c |
870 | relationships of the class the B<Class::MOP::Class> instance is |
871 | associated with. Basically, it can get and set the C<@ISA> for you. |
552e3d24 |
872 | |
343203ee |
873 | B<NOTE:> |
874 | Perl will occasionally perform some C<@ISA> and method caching, if |
875 | you decide to change your superclass relationship at runtime (which |
876 | is quite insane and very much not recommened), then you should be |
877 | aware of this and the fact that this module does not make any |
878 | attempt to address this issue. |
879 | |
552e3d24 |
880 | =item B<class_precedence_list> |
881 | |
a2e85e6c |
882 | This computes the a list of all the class's ancestors in the same order |
883 | in which method dispatch will be done. This is similair to |
884 | what B<Class::ISA::super_path> does, but we don't remove duplicate names. |
552e3d24 |
885 | |
886 | =back |
887 | |
888 | =head2 Methods |
889 | |
890 | =over 4 |
891 | |
2e41896e |
892 | =item B<method_metaclass> |
893 | |
552e3d24 |
894 | =item B<add_method ($method_name, $method)> |
895 | |
896 | This will take a C<$method_name> and CODE reference to that |
a2e85e6c |
897 | C<$method> and install it into the class's package. |
552e3d24 |
898 | |
a2e85e6c |
899 | B<NOTE>: |
900 | This does absolutely nothing special to C<$method> |
552e3d24 |
901 | other than use B<Sub::Name> to make sure it is tagged with the |
902 | correct name, and therefore show up correctly in stack traces and |
903 | such. |
904 | |
663f8198 |
905 | =item B<alias_method ($method_name, $method)> |
906 | |
907 | This will take a C<$method_name> and CODE reference to that |
908 | C<$method> and alias the method into the class's package. |
909 | |
910 | B<NOTE>: |
911 | Unlike C<add_method>, this will B<not> try to name the |
912 | C<$method> using B<Sub::Name>, it only aliases the method in |
913 | the class's package. |
914 | |
552e3d24 |
915 | =item B<has_method ($method_name)> |
916 | |
a2e85e6c |
917 | This just provides a simple way to check if the class implements |
552e3d24 |
918 | a specific C<$method_name>. It will I<not> however, attempt to check |
a2e85e6c |
919 | if the class inherits the method (use C<UNIVERSAL::can> for that). |
552e3d24 |
920 | |
921 | This will correctly handle functions defined outside of the package |
922 | that use a fully qualified name (C<sub Package::name { ... }>). |
923 | |
924 | This will correctly handle functions renamed with B<Sub::Name> and |
925 | installed using the symbol tables. However, if you are naming the |
926 | subroutine outside of the package scope, you must use the fully |
927 | qualified name, including the package name, for C<has_method> to |
928 | correctly identify it. |
929 | |
930 | This will attempt to correctly ignore functions imported from other |
931 | packages using B<Exporter>. It breaks down if the function imported |
932 | is an C<__ANON__> sub (such as with C<use constant>), which very well |
933 | may be a valid method being applied to the class. |
934 | |
935 | In short, this method cannot always be trusted to determine if the |
936 | C<$method_name> is actually a method. However, it will DWIM about |
a2e85e6c |
937 | 90% of the time, so it's a small trade off I think. |
552e3d24 |
938 | |
939 | =item B<get_method ($method_name)> |
940 | |
941 | This will return a CODE reference of the specified C<$method_name>, |
942 | or return undef if that method does not exist. |
943 | |
944 | =item B<remove_method ($method_name)> |
945 | |
a2e85e6c |
946 | This will attempt to remove a given C<$method_name> from the class. |
552e3d24 |
947 | It will return the CODE reference that it has removed, and will |
948 | attempt to use B<Sub::Name> to clear the methods associated name. |
949 | |
950 | =item B<get_method_list> |
951 | |
952 | This will return a list of method names for all I<locally> defined |
953 | methods. It does B<not> provide a list of all applicable methods, |
954 | including any inherited ones. If you want a list of all applicable |
955 | methods, use the C<compute_all_applicable_methods> method. |
956 | |
957 | =item B<compute_all_applicable_methods> |
958 | |
a2e85e6c |
959 | This will return a list of all the methods names this class will |
960 | respond to, taking into account inheritance. The list will be a list of |
552e3d24 |
961 | HASH references, each one containing the following information; method |
962 | name, the name of the class in which the method lives and a CODE |
963 | reference for the actual method. |
964 | |
965 | =item B<find_all_methods_by_name ($method_name)> |
966 | |
967 | This will traverse the inheritence hierarchy and locate all methods |
968 | with a given C<$method_name>. Similar to |
969 | C<compute_all_applicable_methods> it returns a list of HASH references |
970 | with the following information; method name (which will always be the |
971 | same as C<$method_name>), the name of the class in which the method |
972 | lives and a CODE reference for the actual method. |
973 | |
974 | The list of methods produced is a distinct list, meaning there are no |
975 | duplicates in it. This is especially useful for things like object |
976 | initialization and destruction where you only want the method called |
977 | once, and in the correct order. |
978 | |
96ceced8 |
979 | =item B<find_next_method_by_name ($method_name)> |
980 | |
981 | This will return the first method to match a given C<$method_name> in |
982 | the superclasses, this is basically equivalent to calling |
983 | C<SUPER::$method_name>, but it can be dispatched at runtime. |
984 | |
552e3d24 |
985 | =back |
986 | |
a4258ffd |
987 | =head2 Method Modifiers |
988 | |
96ceced8 |
989 | Method modifiers are a concept borrowed from CLOS, in which a method |
990 | can be wrapped with I<before>, I<after> and I<around> method modifiers |
991 | that will be called everytime the method is called. |
992 | |
993 | =head3 How method modifiers work? |
994 | |
995 | Method modifiers work by wrapping the original method and then replacing |
996 | it in the classes symbol table. The wrappers will handle calling all the |
997 | modifiers in the appropariate orders and preserving the calling context |
998 | for the original method. |
999 | |
1000 | Each method modifier serves a particular purpose, which may not be |
1001 | obvious to users of other method wrapping modules. To start with, the |
1002 | return values of I<before> and I<after> modifiers are ignored. This is |
1003 | because thier purpose is B<not> to filter the input and output of the |
1004 | primary method (this is done with an I<around> modifier). This may seem |
1005 | like an odd restriction to some, but doing this allows for simple code |
1006 | to be added at the begining or end of a method call without jeapordizing |
1007 | the normal functioning of the primary method or placing any extra |
1008 | responsibility on the code of the modifier. Of course if you have more |
1009 | complex needs, then use the I<around> modifier, which uses a variation |
1010 | of continutation passing style to allow for a high degree of flexibility. |
1011 | |
1012 | Before and around modifiers are called in last-defined-first-called order, |
1013 | while after modifiers are called in first-defined-first-called order. So |
1014 | the call tree might looks something like this: |
1015 | |
1016 | before 2 |
1017 | before 1 |
1018 | around 2 |
1019 | around 1 |
1020 | primary |
1021 | after 1 |
1022 | after 2 |
1023 | |
1024 | To see examples of using method modifiers, see the following examples |
1025 | included in the distribution; F<InstanceCountingClass>, F<Perl6Attribute>, |
1026 | F<AttributesWithHistory> and F<C3MethodDispatchOrder>. There is also a |
1027 | classic CLOS usage example in the test F<017_add_method_modifier.t>. |
1028 | |
1029 | =head3 What is the performance impact? |
1030 | |
1031 | Of course there is a performance cost associated with method modifiers, |
1032 | but we have made every effort to make that cost be directly proportional |
1033 | to the amount of modifier features you utilize. |
1034 | |
1035 | The wrapping method does it's best to B<only> do as much work as it |
1036 | absolutely needs to. In order to do this we have moved some of the |
1037 | performance costs to set-up time, where they are easier to amortize. |
1038 | |
1039 | All this said, my benchmarks have indicated the following: |
1040 | |
1041 | simple wrapper with no modifiers 100% slower |
1042 | simple wrapper with simple before modifier 400% slower |
1043 | simple wrapper with simple after modifier 450% slower |
1044 | simple wrapper with simple around modifier 500-550% slower |
1045 | simple wrapper with all 3 modifiers 1100% slower |
1046 | |
1047 | These numbers may seem daunting, but you must remember, every feature |
1048 | comes with some cost. To put things in perspective, just doing a simple |
1049 | C<AUTOLOAD> which does nothing but extract the name of the method called |
1050 | and return it costs about 400% over a normal method call. |
1051 | |
a4258ffd |
1052 | =over 4 |
1053 | |
1054 | =item B<add_before_method_modifier ($method_name, $code)> |
1055 | |
96ceced8 |
1056 | This will wrap the method at C<$method_name> and the supplied C<$code> |
1057 | will be passed the C<@_> arguments, and called before the original |
1058 | method is called. As specified above, the return value of the I<before> |
1059 | method modifiers is ignored, and it's ability to modify C<@_> is |
1060 | fairly limited. If you need to do either of these things, use an |
1061 | C<around> method modifier. |
1062 | |
a4258ffd |
1063 | =item B<add_after_method_modifier ($method_name, $code)> |
1064 | |
96ceced8 |
1065 | This will wrap the method at C<$method_name> so that the original |
1066 | method will be called, it's return values stashed, and then the |
1067 | supplied C<$code> will be passed the C<@_> arguments, and called. |
1068 | As specified above, the return value of the I<after> method |
1069 | modifiers is ignored, and it cannot modify the return values of |
1070 | the original method. If you need to do either of these things, use an |
1071 | C<around> method modifier. |
1072 | |
a4258ffd |
1073 | =item B<add_around_method_modifier ($method_name, $code)> |
1074 | |
96ceced8 |
1075 | This will wrap the method at C<$method_name> so that C<$code> |
1076 | will be called and passed the original method as an extra argument |
1077 | at the begining of the C<@_> argument list. This is a variation of |
1078 | continuation passing style, where the function prepended to C<@_> |
1079 | can be considered a continuation. It is up to C<$code> if it calls |
1080 | the original method or not, there is no restriction on what the |
1081 | C<$code> can or cannot do. |
1082 | |
a4258ffd |
1083 | =back |
1084 | |
552e3d24 |
1085 | =head2 Attributes |
1086 | |
1087 | It should be noted that since there is no one consistent way to define |
1088 | the attributes of a class in Perl 5. These methods can only work with |
1089 | the information given, and can not easily discover information on |
a2e85e6c |
1090 | their own. See L<Class::MOP::Attribute> for more details. |
552e3d24 |
1091 | |
1092 | =over 4 |
1093 | |
2e41896e |
1094 | =item B<attribute_metaclass> |
1095 | |
7b31baf4 |
1096 | =item B<get_attribute_map> |
1097 | |
552e3d24 |
1098 | =item B<add_attribute ($attribute_name, $attribute_meta_object)> |
1099 | |
a2e85e6c |
1100 | This stores a C<$attribute_meta_object> in the B<Class::MOP::Class> |
1101 | instance associated with the given class, and associates it with |
1102 | the C<$attribute_name>. Unlike methods, attributes within the MOP |
1103 | are stored as meta-information only. They will be used later to |
1104 | construct instances from (see C<construct_instance> above). |
552e3d24 |
1105 | More details about the attribute meta-objects can be found in the |
a2e85e6c |
1106 | L<Class::MOP::Attribute> or the L<Class::MOP/The Attribute protocol> |
1107 | section. |
1108 | |
1109 | It should be noted that any accessor, reader/writer or predicate |
1110 | methods which the C<$attribute_meta_object> has will be installed |
1111 | into the class at this time. |
552e3d24 |
1112 | |
1113 | =item B<has_attribute ($attribute_name)> |
1114 | |
a2e85e6c |
1115 | Checks to see if this class has an attribute by the name of |
552e3d24 |
1116 | C<$attribute_name> and returns a boolean. |
1117 | |
1118 | =item B<get_attribute ($attribute_name)> |
1119 | |
1120 | Returns the attribute meta-object associated with C<$attribute_name>, |
1121 | if none is found, it will return undef. |
1122 | |
1123 | =item B<remove_attribute ($attribute_name)> |
1124 | |
1125 | This will remove the attribute meta-object stored at |
1126 | C<$attribute_name>, then return the removed attribute meta-object. |
1127 | |
a2e85e6c |
1128 | B<NOTE:> |
1129 | Removing an attribute will only affect future instances of |
552e3d24 |
1130 | the class, it will not make any attempt to remove the attribute from |
1131 | any existing instances of the class. |
1132 | |
a2e85e6c |
1133 | It should be noted that any accessor, reader/writer or predicate |
1134 | methods which the attribute meta-object stored at C<$attribute_name> |
1135 | has will be removed from the class at this time. This B<will> make |
1136 | these attributes somewhat inaccessable in previously created |
1137 | instances. But if you are crazy enough to do this at runtime, then |
1138 | you are crazy enough to deal with something like this :). |
1139 | |
552e3d24 |
1140 | =item B<get_attribute_list> |
1141 | |
1142 | This returns a list of attribute names which are defined in the local |
1143 | class. If you want a list of all applicable attributes for a class, |
1144 | use the C<compute_all_applicable_attributes> method. |
1145 | |
1146 | =item B<compute_all_applicable_attributes> |
1147 | |
c9e77dbb |
1148 | This will traverse the inheritance heirachy and return a list of all |
1149 | the applicable attributes for this class. It does not construct a |
1150 | HASH reference like C<compute_all_applicable_methods> because all |
1151 | that same information is discoverable through the attribute |
1152 | meta-object itself. |
552e3d24 |
1153 | |
058c1cf5 |
1154 | =item B<find_attribute_by_name ($attr_name)> |
1155 | |
1156 | This method will traverse the inheritance heirachy and find the |
1157 | first attribute whose name matches C<$attr_name>, then return it. |
1158 | It will return undef if nothing is found. |
1159 | |
552e3d24 |
1160 | =back |
1161 | |
52e8a34c |
1162 | =head2 Package Variables |
1163 | |
1164 | Since Perl's classes are built atop the Perl package system, it is |
1165 | fairly common to use package scoped variables for things like static |
1166 | class variables. The following methods are convience methods for |
1167 | the creation and inspection of package scoped variables. |
1168 | |
1169 | =over 4 |
1170 | |
1171 | =item B<add_package_variable ($variable_name, ?$initial_value)> |
1172 | |
1173 | Given a C<$variable_name>, which must contain a leading sigil, this |
1174 | method will create that variable within the package which houses the |
1175 | class. It also takes an optional C<$initial_value>, which must be a |
1176 | reference of the same type as the sigil of the C<$variable_name> |
1177 | implies. |
1178 | |
1179 | =item B<get_package_variable ($variable_name)> |
1180 | |
1181 | This will return a reference to the package variable in |
1182 | C<$variable_name>. |
1183 | |
1184 | =item B<has_package_variable ($variable_name)> |
1185 | |
1186 | Returns true (C<1>) if there is a package variable defined for |
1187 | C<$variable_name>, and false (C<0>) otherwise. |
1188 | |
1189 | =item B<remove_package_variable ($variable_name)> |
1190 | |
1191 | This will attempt to remove the package variable at C<$variable_name>. |
1192 | |
1193 | =back |
1194 | |
8b978dd5 |
1195 | =head1 AUTHOR |
1196 | |
a2e85e6c |
1197 | Stevan Little E<lt>stevan@iinteractive.comE<gt> |
8b978dd5 |
1198 | |
1199 | =head1 COPYRIGHT AND LICENSE |
1200 | |
1201 | Copyright 2006 by Infinity Interactive, Inc. |
1202 | |
1203 | L<http://www.iinteractive.com> |
1204 | |
1205 | This library is free software; you can redistribute it and/or modify |
1206 | it under the same terms as Perl itself. |
1207 | |
1208 | =cut |