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 | |
bd4e03f9 |
12 | our $VERSION = '0.12'; |
8b978dd5 |
13 | |
aa448b16 |
14 | # Self-introspection |
2eb717d5 |
15 | |
aa448b16 |
16 | sub meta { Class::MOP::Class->initialize(blessed($_[0]) || $_[0]) } |
2eb717d5 |
17 | |
8b978dd5 |
18 | # Creation |
19 | |
bb8dacfa |
20 | #{ |
bfe4d0fc |
21 | # Metaclasses are singletons, so we cache them here. |
22 | # there is no need to worry about destruction though |
23 | # because they should die only when the program dies. |
24 | # After all, do package definitions even get reaped? |
587aca23 |
25 | my %METAS; |
26 | |
27 | # means of accessing all the metaclasses that have |
28 | # been initialized thus far (for mugwumps obj browser) |
29 | sub get_all_metaclasses { %METAS } |
30 | sub get_all_metaclass_instances { values %METAS } |
31 | sub get_all_metaclass_names { keys %METAS } |
651955fb |
32 | |
bfe4d0fc |
33 | sub initialize { |
351bd7d4 |
34 | my $class = shift; |
35 | my $package_name = shift; |
22286063 |
36 | (defined $package_name && $package_name && !blessed($package_name)) |
37 | || confess "You must pass a package name and it cannot be blessed"; |
651955fb |
38 | $class->construct_class_instance(':package' => $package_name, @_); |
727919c5 |
39 | } |
40 | |
41 | # NOTE: (meta-circularity) |
42 | # this is a special form of &construct_instance |
43 | # (see below), which is used to construct class |
1a7ebbb3 |
44 | # meta-object instances for any Class::MOP::* |
45 | # class. All other classes will use the more |
46 | # normal &construct_instance. |
727919c5 |
47 | sub construct_class_instance { |
351bd7d4 |
48 | my $class = shift; |
651955fb |
49 | my %options = @_; |
50 | my $package_name = $options{':package'}; |
727919c5 |
51 | (defined $package_name && $package_name) |
651955fb |
52 | || confess "You must pass a package name"; |
2f6d5412 |
53 | # NOTE: |
54 | # return the metaclass if we have it cached, |
55 | # and it is still defined (it has not been |
56 | # reaped by DESTROY yet, which can happen |
57 | # annoyingly enough during global destruction) |
58 | return $METAS{$package_name} |
59 | if exists $METAS{$package_name} && defined $METAS{$package_name}; |
1a7ebbb3 |
60 | $class = blessed($class) || $class; |
550d56db |
61 | # now create the metaclass |
62 | my $meta; |
1a7ebbb3 |
63 | if ($class =~ /^Class::MOP::/) { |
550d56db |
64 | $meta = bless { |
351bd7d4 |
65 | '$:package' => $package_name, |
66 | '%:attributes' => {}, |
550d56db |
67 | '$:attribute_metaclass' => $options{':attribute_metaclass'} || 'Class::MOP::Attribute', |
68 | '$:method_metaclass' => $options{':method_metaclass'} || 'Class::MOP::Method', |
1a7ebbb3 |
69 | } => $class; |
70 | } |
71 | else { |
5f3c057a |
72 | # NOTE: |
73 | # it is safe to use meta here because |
74 | # class will always be a subclass of |
75 | # Class::MOP::Class, which defines meta |
550d56db |
76 | $meta = bless $class->meta->construct_instance(%options) => $class |
1a7ebbb3 |
77 | } |
550d56db |
78 | # and check the metaclass compatibility |
79 | $meta->check_metaclass_compatability(); |
80 | $METAS{$package_name} = $meta; |
81 | } |
82 | |
83 | sub check_metaclass_compatability { |
84 | my $self = shift; |
85 | |
86 | # this is always okay ... |
87 | return if blessed($self) eq 'Class::MOP::Class'; |
88 | |
89 | my @class_list = $self->class_precedence_list; |
90 | shift @class_list; # shift off $self->name |
91 | |
92 | foreach my $class_name (@class_list) { |
96ceced8 |
93 | my $meta = $METAS{$class_name} || next; |
550d56db |
94 | ($self->isa(blessed($meta))) |
95 | || confess $self->name . "->meta => (" . (blessed($self)) . ")" . |
96 | " is not compatible with the " . |
97 | $class_name . "->meta => (" . (blessed($meta)) . ")"; |
98 | } |
bfe4d0fc |
99 | } |
bb8dacfa |
100 | #} |
8b978dd5 |
101 | |
102 | sub create { |
103 | my ($class, $package_name, $package_version, %options) = @_; |
bfe4d0fc |
104 | (defined $package_name && $package_name) |
8b978dd5 |
105 | || confess "You must pass a package name"; |
106 | my $code = "package $package_name;"; |
107 | $code .= "\$$package_name\:\:VERSION = '$package_version';" |
108 | if defined $package_version; |
109 | eval $code; |
110 | confess "creation of $package_name failed : $@" if $@; |
bfe4d0fc |
111 | my $meta = $class->initialize($package_name); |
aa448b16 |
112 | |
113 | $meta->add_method('meta' => sub { |
114 | Class::MOP::Class->initialize(blessed($_[0]) || $_[0]); |
115 | }); |
116 | |
8b978dd5 |
117 | $meta->superclasses(@{$options{superclasses}}) |
118 | if exists $options{superclasses}; |
2eb717d5 |
119 | # NOTE: |
120 | # process attributes first, so that they can |
121 | # install accessors, but locally defined methods |
122 | # can then overwrite them. It is maybe a little odd, but |
123 | # I think this should be the order of things. |
124 | if (exists $options{attributes}) { |
cbd9f942 |
125 | foreach my $attr (@{$options{attributes}}) { |
126 | $meta->add_attribute($attr); |
2eb717d5 |
127 | } |
128 | } |
bfe4d0fc |
129 | if (exists $options{methods}) { |
130 | foreach my $method_name (keys %{$options{methods}}) { |
131 | $meta->add_method($method_name, $options{methods}->{$method_name}); |
132 | } |
2eb717d5 |
133 | } |
8b978dd5 |
134 | return $meta; |
135 | } |
136 | |
c3e7c446 |
137 | { |
4d154c08 |
138 | # NOTE: |
139 | # this should be sufficient, if you have a |
140 | # use case where it is not, write a test and |
141 | # I will change it. |
c3e7c446 |
142 | my $ANON_CLASS_SERIAL = 0; |
4d154c08 |
143 | |
c3e7c446 |
144 | sub create_anon_class { |
145 | my ($class, %options) = @_; |
146 | my $package_name = 'Class::MOP::Class::__ANON__::SERIAL::' . ++$ANON_CLASS_SERIAL; |
147 | return $class->create($package_name, '0.00', %options); |
148 | } |
587aca23 |
149 | } |
150 | |
7b31baf4 |
151 | ## Attribute readers |
152 | |
153 | # NOTE: |
154 | # all these attribute readers will be bootstrapped |
155 | # away in the Class::MOP bootstrap section |
156 | |
157 | sub name { $_[0]->{'$:package'} } |
158 | sub get_attribute_map { $_[0]->{'%:attributes'} } |
159 | sub attribute_metaclass { $_[0]->{'$:attribute_metaclass'} } |
160 | sub method_metaclass { $_[0]->{'$:method_metaclass'} } |
161 | |
c9e77dbb |
162 | # Instance Construction & Cloning |
163 | |
5f3c057a |
164 | sub new_object { |
165 | my $class = shift; |
651955fb |
166 | # NOTE: |
167 | # we need to protect the integrity of the |
168 | # Class::MOP::Class singletons here, so we |
169 | # delegate this to &construct_class_instance |
170 | # which will deal with the singletons |
171 | return $class->construct_class_instance(@_) |
172 | if $class->name->isa('Class::MOP::Class'); |
5f3c057a |
173 | bless $class->construct_instance(@_) => $class->name; |
174 | } |
e16da3e6 |
175 | |
176 | sub construct_instance { |
cbd9f942 |
177 | my ($class, %params) = @_; |
178 | my $instance = {}; |
c9e77dbb |
179 | foreach my $attr ($class->compute_all_applicable_attributes()) { |
fed4cee7 |
180 | $attr->initialize_instance_slot($class, $instance, \%params); |
cbd9f942 |
181 | } |
182 | return $instance; |
e16da3e6 |
183 | } |
184 | |
5f3c057a |
185 | sub clone_object { |
186 | my $class = shift; |
7b31baf4 |
187 | my $instance = shift; |
651955fb |
188 | (blessed($instance) && $instance->isa($class->name)) |
189 | || confess "You must pass an instance ($instance) of the metaclass (" . $class->name . ")"; |
190 | # NOTE: |
191 | # we need to protect the integrity of the |
192 | # Class::MOP::Class singletons here, they |
a740253a |
193 | # should not be cloned. |
651955fb |
194 | return $instance if $instance->isa('Class::MOP::Class'); |
195 | bless $class->clone_instance($instance, @_) => blessed($instance); |
5f3c057a |
196 | } |
197 | |
c9e77dbb |
198 | sub clone_instance { |
651955fb |
199 | my ($class, $instance, %params) = @_; |
200 | (blessed($instance)) |
c9e77dbb |
201 | || confess "You can only clone instances, \$self is not a blessed instance"; |
19d4b5b8 |
202 | my $clone = { %$instance, %params }; |
c9e77dbb |
203 | return $clone; |
204 | } |
205 | |
8b978dd5 |
206 | # Informational |
207 | |
7b31baf4 |
208 | # &name should be here too, but it is above |
209 | # because it gets bootstrapped away |
8b978dd5 |
210 | |
211 | sub version { |
212 | my $self = shift; |
96ceced8 |
213 | ${$self->get_package_variable('$VERSION')}; |
8b978dd5 |
214 | } |
215 | |
216 | # Inheritance |
217 | |
218 | sub superclasses { |
219 | my $self = shift; |
e7f732e4 |
220 | no strict 'refs'; |
8b978dd5 |
221 | if (@_) { |
222 | my @supers = @_; |
e7f732e4 |
223 | @{$self->name . '::ISA'} = @supers; |
8b978dd5 |
224 | } |
e7f732e4 |
225 | @{$self->name . '::ISA'}; |
8b978dd5 |
226 | } |
227 | |
228 | sub class_precedence_list { |
229 | my $self = shift; |
bfe4d0fc |
230 | # NOTE: |
231 | # We need to check for ciruclar inheirtance here. |
232 | # This will do nothing if all is well, and blow |
233 | # up otherwise. Yes, it's an ugly hack, better |
234 | # suggestions are welcome. |
235 | { $self->name->isa('This is a test for circular inheritance') } |
8c936afc |
236 | # ... and now back to our regularly scheduled program |
8b978dd5 |
237 | ( |
238 | $self->name, |
239 | map { |
adfe5cc9 |
240 | # OPTIMIZATION NOTE: |
241 | # we grab the metaclass from the %METAS |
242 | # hash here to save the initialize() call |
243 | # if we can, but it is not always possible |
bb8dacfa |
244 | ($METAS{$_} || $self->initialize($_))->class_precedence_list() |
8b978dd5 |
245 | } $self->superclasses() |
246 | ); |
247 | } |
248 | |
0882828e |
249 | ## Methods |
250 | |
251 | sub add_method { |
252 | my ($self, $method_name, $method) = @_; |
253 | (defined $method_name && $method_name) |
254 | || confess "You must define a method name"; |
a5eca695 |
255 | # use reftype here to allow for blessed subs ... |
ee5e71d4 |
256 | ('CODE' eq (reftype($method) || '')) |
0882828e |
257 | || confess "Your code block must be a CODE reference"; |
258 | my $full_method_name = ($self->name . '::' . $method_name); |
de19f115 |
259 | |
a4258ffd |
260 | $method = $self->method_metaclass->wrap($method) unless blessed($method); |
de19f115 |
261 | |
0882828e |
262 | no strict 'refs'; |
c9b8b7f9 |
263 | no warnings 'redefine'; |
22286063 |
264 | *{$full_method_name} = subname $full_method_name => $method; |
0882828e |
265 | } |
266 | |
a4258ffd |
267 | { |
268 | my $fetch_and_prepare_method = sub { |
269 | my ($self, $method_name) = @_; |
270 | # fetch it locally |
271 | my $method = $self->get_method($method_name); |
272 | # if we dont have local ... |
273 | unless ($method) { |
96ceced8 |
274 | # make sure this method even exists ... |
275 | ($self->find_next_method_by_name($method_name)) |
276 | || confess "The method '$method_name' is not found in the inherience hierarchy for this class"; |
277 | # if so, then create a local which just |
278 | # calls the next applicable method ... |
279 | $self->add_method($method_name => sub { |
280 | $self->find_next_method_by_name($method_name)->(@_); |
281 | }); |
a4258ffd |
282 | $method = $self->get_method($method_name); |
283 | } |
284 | |
285 | # now make sure we wrap it properly |
286 | # (if it isnt already) |
287 | unless ($method->isa('Class::MOP::Method::Wrapped')) { |
288 | $method = Class::MOP::Method::Wrapped->wrap($method); |
289 | $self->add_method($method_name => $method); |
290 | } |
291 | return $method; |
292 | }; |
293 | |
294 | sub add_before_method_modifier { |
295 | my ($self, $method_name, $method_modifier) = @_; |
296 | (defined $method_name && $method_name) |
8c936afc |
297 | || confess "You must pass in a method name"; |
a4258ffd |
298 | my $method = $fetch_and_prepare_method->($self, $method_name); |
8c936afc |
299 | $method->add_before_modifier(subname ':before' => $method_modifier); |
a4258ffd |
300 | } |
ddc8edba |
301 | |
a4258ffd |
302 | sub add_after_method_modifier { |
303 | my ($self, $method_name, $method_modifier) = @_; |
304 | (defined $method_name && $method_name) |
8c936afc |
305 | || confess "You must pass in a method name"; |
a4258ffd |
306 | my $method = $fetch_and_prepare_method->($self, $method_name); |
8c936afc |
307 | $method->add_after_modifier(subname ':after' => $method_modifier); |
ddc8edba |
308 | } |
309 | |
a4258ffd |
310 | sub add_around_method_modifier { |
311 | my ($self, $method_name, $method_modifier) = @_; |
312 | (defined $method_name && $method_name) |
313 | || confess "You must pass in a method name"; |
a4258ffd |
314 | my $method = $fetch_and_prepare_method->($self, $method_name); |
8c936afc |
315 | $method->add_around_modifier(subname ':around' => $method_modifier); |
a4258ffd |
316 | } |
317 | |
8c936afc |
318 | # NOTE: |
319 | # the methods above used to be named like this: |
320 | # ${pkg}::${method}:(before|after|around) |
321 | # but this proved problematic when using one modifier |
322 | # to wrap multiple methods (something which is likely |
323 | # to happen pretty regularly IMO). So instead of naming |
324 | # it like this, I have chosen to just name them purely |
325 | # with their modifier names, like so: |
326 | # :(before|after|around) |
327 | # The fact is that in a stack trace, it will be fairly |
328 | # evident from the context what method they are attached |
329 | # to, and so don't need the fully qualified name. |
ee5e71d4 |
330 | } |
331 | |
663f8198 |
332 | sub alias_method { |
333 | my ($self, $method_name, $method) = @_; |
334 | (defined $method_name && $method_name) |
335 | || confess "You must define a method name"; |
336 | # use reftype here to allow for blessed subs ... |
ee5e71d4 |
337 | ('CODE' eq (reftype($method) || '')) |
663f8198 |
338 | || confess "Your code block must be a CODE reference"; |
de19f115 |
339 | my $full_method_name = ($self->name . '::' . $method_name); |
340 | |
a4258ffd |
341 | $method = $self->method_metaclass->wrap($method) unless blessed($method); |
663f8198 |
342 | |
343 | no strict 'refs'; |
344 | no warnings 'redefine'; |
345 | *{$full_method_name} = $method; |
346 | } |
347 | |
de19f115 |
348 | sub has_method { |
349 | my ($self, $method_name) = @_; |
350 | (defined $method_name && $method_name) |
351 | || confess "You must define a method name"; |
bfe4d0fc |
352 | |
de19f115 |
353 | my $sub_name = ($self->name . '::' . $method_name); |
0882828e |
354 | |
de19f115 |
355 | no strict 'refs'; |
356 | return 0 if !defined(&{$sub_name}); |
de19f115 |
357 | my $method = \&{$sub_name}; |
96ceced8 |
358 | return 0 if (svref_2object($method)->GV->STASH->NAME || '') ne $self->name && |
359 | (svref_2object($method)->GV->NAME || '') ne '__ANON__'; |
de19f115 |
360 | |
96ceced8 |
361 | # at this point we are relatively sure |
362 | # it is our method, so we bless/wrap it |
363 | $self->method_metaclass->wrap($method) unless blessed($method); |
de19f115 |
364 | return 1; |
0882828e |
365 | } |
366 | |
367 | sub get_method { |
c9b8b7f9 |
368 | my ($self, $method_name) = @_; |
0882828e |
369 | (defined $method_name && $method_name) |
370 | || confess "You must define a method name"; |
371 | |
de19f115 |
372 | return unless $self->has_method($method_name); |
373 | |
0882828e |
374 | no strict 'refs'; |
de19f115 |
375 | return \&{$self->name . '::' . $method_name}; |
c9b8b7f9 |
376 | } |
377 | |
378 | sub remove_method { |
379 | my ($self, $method_name) = @_; |
380 | (defined $method_name && $method_name) |
381 | || confess "You must define a method name"; |
382 | |
383 | my $removed_method = $self->get_method($method_name); |
384 | |
385 | no strict 'refs'; |
386 | delete ${$self->name . '::'}{$method_name} |
387 | if defined $removed_method; |
388 | |
389 | return $removed_method; |
390 | } |
391 | |
392 | sub get_method_list { |
393 | my $self = shift; |
394 | no strict 'refs'; |
a5eca695 |
395 | grep { $self->has_method($_) } %{$self->name . '::'}; |
396 | } |
397 | |
398 | sub compute_all_applicable_methods { |
399 | my $self = shift; |
400 | my @methods; |
401 | # keep a record of what we have seen |
402 | # here, this will handle all the |
403 | # inheritence issues because we are |
404 | # using the &class_precedence_list |
405 | my (%seen_class, %seen_method); |
406 | foreach my $class ($self->class_precedence_list()) { |
407 | next if $seen_class{$class}; |
408 | $seen_class{$class}++; |
409 | # fetch the meta-class ... |
410 | my $meta = $self->initialize($class); |
411 | foreach my $method_name ($meta->get_method_list()) { |
412 | next if exists $seen_method{$method_name}; |
413 | $seen_method{$method_name}++; |
414 | push @methods => { |
415 | name => $method_name, |
416 | class => $class, |
417 | code => $meta->get_method($method_name) |
418 | }; |
419 | } |
420 | } |
421 | return @methods; |
422 | } |
423 | |
a5eca695 |
424 | sub find_all_methods_by_name { |
425 | my ($self, $method_name) = @_; |
426 | (defined $method_name && $method_name) |
427 | || confess "You must define a method name to find"; |
428 | my @methods; |
429 | # keep a record of what we have seen |
430 | # here, this will handle all the |
431 | # inheritence issues because we are |
432 | # using the &class_precedence_list |
433 | my %seen_class; |
434 | foreach my $class ($self->class_precedence_list()) { |
435 | next if $seen_class{$class}; |
436 | $seen_class{$class}++; |
437 | # fetch the meta-class ... |
96ceced8 |
438 | my $meta = $self->initialize($class); |
a5eca695 |
439 | push @methods => { |
440 | name => $method_name, |
441 | class => $class, |
442 | code => $meta->get_method($method_name) |
443 | } if $meta->has_method($method_name); |
444 | } |
445 | return @methods; |
8b978dd5 |
446 | } |
447 | |
96ceced8 |
448 | sub find_next_method_by_name { |
449 | my ($self, $method_name) = @_; |
450 | (defined $method_name && $method_name) |
451 | || confess "You must define a method name to find"; |
452 | # keep a record of what we have seen |
453 | # here, this will handle all the |
454 | # inheritence issues because we are |
455 | # using the &class_precedence_list |
456 | my %seen_class; |
457 | my @cpl = $self->class_precedence_list(); |
458 | shift @cpl; # discard ourselves |
459 | foreach my $class (@cpl) { |
460 | next if $seen_class{$class}; |
461 | $seen_class{$class}++; |
462 | # fetch the meta-class ... |
463 | my $meta = $self->initialize($class); |
464 | return $meta->get_method($method_name) |
465 | if $meta->has_method($method_name); |
466 | } |
467 | return; |
468 | } |
469 | |
552e3d24 |
470 | ## Attributes |
471 | |
e16da3e6 |
472 | sub add_attribute { |
2e41896e |
473 | my $self = shift; |
474 | # either we have an attribute object already |
475 | # or we need to create one from the args provided |
476 | my $attribute = blessed($_[0]) ? $_[0] : $self->attribute_metaclass->new(@_); |
477 | # make sure it is derived from the correct type though |
478 | ($attribute->isa('Class::MOP::Attribute')) |
479 | || confess "Your attribute must be an instance of Class::MOP::Attribute (or a subclass)"; |
9ec169fe |
480 | $attribute->attach_to_class($self); |
481 | $attribute->install_accessors(); |
291073fc |
482 | $self->get_attribute_map->{$attribute->name} = $attribute; |
e16da3e6 |
483 | } |
484 | |
485 | sub has_attribute { |
486 | my ($self, $attribute_name) = @_; |
487 | (defined $attribute_name && $attribute_name) |
488 | || confess "You must define an attribute name"; |
291073fc |
489 | exists $self->get_attribute_map->{$attribute_name} ? 1 : 0; |
e16da3e6 |
490 | } |
491 | |
492 | sub get_attribute { |
493 | my ($self, $attribute_name) = @_; |
494 | (defined $attribute_name && $attribute_name) |
495 | || confess "You must define an attribute name"; |
bb8dacfa |
496 | # OPTIMIZATION NOTE: |
497 | # we used to say `if $self->has_attribute($attribute_name)` |
498 | # here, but since get_attribute is called so often, we |
499 | # eliminate the function call here |
500 | return $self->{'%:attributes'}->{$attribute_name} |
501 | if exists $self->{'%:attributes'}->{$attribute_name}; |
22286063 |
502 | return; |
e16da3e6 |
503 | } |
504 | |
505 | sub remove_attribute { |
506 | my ($self, $attribute_name) = @_; |
507 | (defined $attribute_name && $attribute_name) |
508 | || confess "You must define an attribute name"; |
7b31baf4 |
509 | my $removed_attribute = $self->get_attribute_map->{$attribute_name}; |
22286063 |
510 | return unless defined $removed_attribute; |
511 | delete $self->get_attribute_map->{$attribute_name}; |
9ec169fe |
512 | $removed_attribute->remove_accessors(); |
513 | $removed_attribute->detach_from_class(); |
e16da3e6 |
514 | return $removed_attribute; |
515 | } |
516 | |
517 | sub get_attribute_list { |
518 | my $self = shift; |
bb8dacfa |
519 | # OPTIMIZATION NOTE: |
520 | # We don't use get_attribute_map here because |
521 | # we ask for the attribute list quite often |
522 | # in compute_all_applicable_attributes, so |
523 | # eliminating the function call helps |
524 | keys %{$self->{'%:attributes'}}; |
e16da3e6 |
525 | } |
526 | |
527 | sub compute_all_applicable_attributes { |
528 | my $self = shift; |
529 | my @attrs; |
530 | # keep a record of what we have seen |
531 | # here, this will handle all the |
532 | # inheritence issues because we are |
533 | # using the &class_precedence_list |
534 | my (%seen_class, %seen_attr); |
535 | foreach my $class ($self->class_precedence_list()) { |
536 | next if $seen_class{$class}; |
537 | $seen_class{$class}++; |
538 | # fetch the meta-class ... |
adfe5cc9 |
539 | # OPTIMIZATION NOTE: |
540 | # we grab the metaclass from the %METAS |
541 | # hash here to save the initialize() call |
542 | my $meta = $METAS{$class}; |
e16da3e6 |
543 | foreach my $attr_name ($meta->get_attribute_list()) { |
544 | next if exists $seen_attr{$attr_name}; |
545 | $seen_attr{$attr_name}++; |
c9e77dbb |
546 | push @attrs => $meta->get_attribute($attr_name); |
e16da3e6 |
547 | } |
548 | } |
549 | return @attrs; |
550 | } |
2eb717d5 |
551 | |
058c1cf5 |
552 | sub find_attribute_by_name { |
553 | my ($self, $attr_name) = @_; |
554 | # keep a record of what we have seen |
555 | # here, this will handle all the |
556 | # inheritence issues because we are |
557 | # using the &class_precedence_list |
558 | my %seen_class; |
559 | foreach my $class ($self->class_precedence_list()) { |
560 | next if $seen_class{$class}; |
561 | $seen_class{$class}++; |
562 | # fetch the meta-class ... |
563 | my $meta = $self->initialize($class); |
564 | return $meta->get_attribute($attr_name) |
565 | if $meta->has_attribute($attr_name); |
566 | } |
567 | return; |
568 | } |
569 | |
52e8a34c |
570 | # Class attributes |
571 | |
572 | sub add_package_variable { |
573 | my ($self, $variable, $initial_value) = @_; |
574 | (defined $variable && $variable =~ /^[\$\@\%]/) |
575 | || confess "variable name does not have a sigil"; |
576 | |
577 | my ($sigil, $name) = ($variable =~ /^(.)(.*)$/); |
578 | if (defined $initial_value) { |
579 | no strict 'refs'; |
580 | *{$self->name . '::' . $name} = $initial_value; |
581 | } |
582 | else { |
39ec4f0c |
583 | my $e; |
584 | { |
585 | # NOTE: |
586 | # We HAVE to localize $@ or all |
587 | # hell breaks loose. It is not |
588 | # good, believe me, not good. |
589 | local $@; |
590 | eval $sigil . $self->name . '::' . $name; |
591 | $e = $@ if $@; |
592 | } |
593 | confess "Could not create package variable ($variable) because : $e" if $e; |
52e8a34c |
594 | } |
595 | } |
596 | |
597 | sub has_package_variable { |
598 | my ($self, $variable) = @_; |
599 | (defined $variable && $variable =~ /^[\$\@\%]/) |
600 | || confess "variable name does not have a sigil"; |
601 | my ($sigil, $name) = ($variable =~ /^(.)(.*)$/); |
602 | no strict 'refs'; |
603 | defined ${$self->name . '::'}{$name} ? 1 : 0; |
604 | } |
605 | |
606 | sub get_package_variable { |
607 | my ($self, $variable) = @_; |
608 | (defined $variable && $variable =~ /^[\$\@\%]/) |
609 | || confess "variable name does not have a sigil"; |
610 | my ($sigil, $name) = ($variable =~ /^(.)(.*)$/); |
39ec4f0c |
611 | my ($ref, $e); |
612 | { |
613 | # NOTE: |
614 | # We HAVE to localize $@ or all |
615 | # hell breaks loose. It is not |
616 | # good, believe me, not good. |
617 | local $@; |
618 | $ref = eval '\\' . $sigil . $self->name . '::' . $name; |
619 | $e = $@ if $@; |
620 | } |
621 | confess "Could not get the package variable ($variable) because : $e" if $e; |
52e8a34c |
622 | # if we didn't die, then we can return it |
18697ac8 |
623 | return $ref; |
52e8a34c |
624 | } |
625 | |
626 | sub remove_package_variable { |
627 | my ($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 | delete ${$self->name . '::'}{$name}; |
633 | } |
634 | |
8b978dd5 |
635 | 1; |
636 | |
637 | __END__ |
638 | |
639 | =pod |
640 | |
641 | =head1 NAME |
642 | |
643 | Class::MOP::Class - Class Meta Object |
644 | |
645 | =head1 SYNOPSIS |
646 | |
8c936afc |
647 | # assuming that class Foo |
648 | # has been defined, you can |
649 | |
fe122940 |
650 | # use this for introspection ... |
651 | |
fe122940 |
652 | # add a method to Foo ... |
653 | Foo->meta->add_method('bar' => sub { ... }) |
654 | |
655 | # get a list of all the classes searched |
656 | # the method dispatcher in the correct order |
657 | Foo->meta->class_precedence_list() |
658 | |
659 | # remove a method from Foo |
660 | Foo->meta->remove_method('bar'); |
661 | |
662 | # or use this to actually create classes ... |
663 | |
664 | Class::MOP::Class->create('Bar' => '0.01' => ( |
665 | superclasses => [ 'Foo' ], |
666 | attributes => [ |
667 | Class::MOP:::Attribute->new('$bar'), |
668 | Class::MOP:::Attribute->new('$baz'), |
669 | ], |
670 | methods => { |
671 | calculate_bar => sub { ... }, |
672 | construct_baz => sub { ... } |
673 | } |
674 | )); |
675 | |
8b978dd5 |
676 | =head1 DESCRIPTION |
677 | |
fe122940 |
678 | This is the largest and currently most complex part of the Perl 5 |
679 | meta-object protocol. It controls the introspection and |
680 | manipulation of Perl 5 classes (and it can create them too). The |
681 | best way to understand what this module can do, is to read the |
682 | documentation for each of it's methods. |
683 | |
552e3d24 |
684 | =head1 METHODS |
685 | |
2eb717d5 |
686 | =head2 Self Introspection |
687 | |
688 | =over 4 |
689 | |
690 | =item B<meta> |
691 | |
fe122940 |
692 | This will return a B<Class::MOP::Class> instance which is related |
693 | to this class. Thereby allowing B<Class::MOP::Class> to actually |
694 | introspect itself. |
695 | |
696 | As with B<Class::MOP::Attribute>, B<Class::MOP> will actually |
697 | bootstrap this module by installing a number of attribute meta-objects |
698 | into it's metaclass. This will allow this class to reap all the benifits |
699 | of the MOP when subclassing it. |
2eb717d5 |
700 | |
587aca23 |
701 | =item B<get_all_metaclasses> |
702 | |
703 | This will return an hash of all the metaclass instances that have |
704 | been cached by B<Class::MOP::Class> keyed by the package name. |
705 | |
706 | =item B<get_all_metaclass_instances> |
707 | |
708 | This will return an array of all the metaclass instances that have |
709 | been cached by B<Class::MOP::Class>. |
710 | |
711 | =item B<get_all_metaclass_names> |
712 | |
713 | This will return an array of all the metaclass names that have |
714 | been cached by B<Class::MOP::Class>. |
715 | |
2eb717d5 |
716 | =back |
717 | |
552e3d24 |
718 | =head2 Class construction |
719 | |
a2e85e6c |
720 | These methods will handle creating B<Class::MOP::Class> objects, |
721 | which can be used to both create new classes, and analyze |
722 | pre-existing classes. |
552e3d24 |
723 | |
724 | This module will internally store references to all the instances |
725 | you create with these methods, so that they do not need to be |
726 | created any more than nessecary. Basically, they are singletons. |
727 | |
728 | =over 4 |
729 | |
730 | =item B<create ($package_name, ?$package_version, |
a2e85e6c |
731 | superclasses =E<gt> ?@superclasses, |
732 | methods =E<gt> ?%methods, |
733 | attributes =E<gt> ?%attributes)> |
552e3d24 |
734 | |
a2e85e6c |
735 | This returns a B<Class::MOP::Class> object, bringing the specified |
552e3d24 |
736 | C<$package_name> into existence and adding any of the |
737 | C<$package_version>, C<@superclasses>, C<%methods> and C<%attributes> |
738 | to it. |
739 | |
587aca23 |
740 | =item B<create_anon_class (superclasses =E<gt> ?@superclasses, |
741 | methods =E<gt> ?%methods, |
742 | attributes =E<gt> ?%attributes)> |
743 | |
744 | This will create an anonymous class, it works much like C<create> but |
745 | it does not need a C<$package_name>. Instead it will create a suitably |
746 | unique package name for you to stash things into. |
747 | |
552e3d24 |
748 | =item B<initialize ($package_name)> |
749 | |
a2e85e6c |
750 | This initializes and returns returns a B<Class::MOP::Class> object |
751 | for a given a C<$package_name>. |
752 | |
651955fb |
753 | =item B<construct_class_instance (%options)> |
a2e85e6c |
754 | |
755 | This will construct an instance of B<Class::MOP::Class>, it is |
756 | here so that we can actually "tie the knot" for B<Class::MOP::Class> |
757 | to use C<construct_instance> once all the bootstrapping is done. This |
758 | method is used internally by C<initialize> and should never be called |
759 | from outside of that method really. |
552e3d24 |
760 | |
550d56db |
761 | =item B<check_metaclass_compatability> |
762 | |
763 | This method is called as the very last thing in the |
764 | C<construct_class_instance> method. This will check that the |
765 | metaclass you are creating is compatible with the metaclasses of all |
766 | your ancestors. For more inforamtion about metaclass compatibility |
767 | see the C<About Metaclass compatibility> section in L<Class::MOP>. |
768 | |
552e3d24 |
769 | =back |
770 | |
c9e77dbb |
771 | =head2 Object instance construction and cloning |
a2e85e6c |
772 | |
c9e77dbb |
773 | These methods are B<entirely optional>, it is up to you whether you want |
774 | to use them or not. |
552e3d24 |
775 | |
776 | =over 4 |
777 | |
5f3c057a |
778 | =item B<new_object (%params)> |
779 | |
780 | This is a convience method for creating a new object of the class, and |
781 | blessing it into the appropriate package as well. Ideally your class |
782 | would call a C<new> this method like so: |
783 | |
784 | sub MyClass::new { |
785 | my ($class, %param) = @_; |
786 | $class->meta->new_object(%params); |
787 | } |
788 | |
789 | Of course the ideal place for this would actually be in C<UNIVERSAL::> |
790 | but that is considered bad style, so we do not do that. |
791 | |
cbd9f942 |
792 | =item B<construct_instance (%params)> |
552e3d24 |
793 | |
c9e77dbb |
794 | This method is used to construct an instace structure suitable for |
795 | C<bless>-ing into your package of choice. It works in conjunction |
796 | with the Attribute protocol to collect all applicable attributes. |
797 | |
cbd9f942 |
798 | This will construct and instance using a HASH ref as storage |
552e3d24 |
799 | (currently only HASH references are supported). This will collect all |
a2e85e6c |
800 | the applicable attributes and layout out the fields in the HASH ref, |
801 | it will then initialize them using either use the corresponding key |
802 | in C<%params> or any default value or initializer found in the |
803 | attribute meta-object. |
727919c5 |
804 | |
5f3c057a |
805 | =item B<clone_object ($instance, %params)> |
806 | |
807 | This is a convience method for cloning an object instance, then |
19d4b5b8 |
808 | blessing it into the appropriate package. This method will call |
809 | C<clone_instance>, which performs a shallow copy of the object, |
810 | see that methods documentation for more details. Ideally your |
811 | class would call a C<clone> this method like so: |
5f3c057a |
812 | |
813 | sub MyClass::clone { |
814 | my ($self, %param) = @_; |
815 | $self->meta->clone_object($self, %params); |
816 | } |
817 | |
818 | Of course the ideal place for this would actually be in C<UNIVERSAL::> |
819 | but that is considered bad style, so we do not do that. |
820 | |
c9e77dbb |
821 | =item B<clone_instance($instance, %params)> |
822 | |
823 | This method is a compliment of C<construct_instance> (which means if |
19d4b5b8 |
824 | you override C<construct_instance>, you need to override this one too), |
825 | and clones the instance shallowly. |
a27ae83f |
826 | |
827 | The cloned structure returned is (like with C<construct_instance>) an |
828 | unC<bless>ed HASH reference, it is your responsibility to then bless |
829 | this cloned structure into the right class (which C<clone_object> will |
830 | do for you). |
c9e77dbb |
831 | |
19d4b5b8 |
832 | As of 0.11, this method will clone the C<$instance> structure shallowly, |
833 | as opposed to the deep cloning implemented in prior versions. After much |
834 | thought, research and discussion, I have decided that anything but basic |
835 | shallow cloning is outside the scope of the meta-object protocol. I |
836 | think Yuval "nothingmuch" Kogman put it best when he said that cloning |
837 | is too I<context-specific> to be part of the MOP. |
838 | |
552e3d24 |
839 | =back |
840 | |
841 | =head2 Informational |
842 | |
843 | =over 4 |
844 | |
845 | =item B<name> |
846 | |
a2e85e6c |
847 | This is a read-only attribute which returns the package name for the |
848 | given B<Class::MOP::Class> instance. |
552e3d24 |
849 | |
850 | =item B<version> |
851 | |
852 | This is a read-only attribute which returns the C<$VERSION> of the |
a2e85e6c |
853 | package for the given B<Class::MOP::Class> instance. |
552e3d24 |
854 | |
855 | =back |
856 | |
857 | =head2 Inheritance Relationships |
858 | |
859 | =over 4 |
860 | |
861 | =item B<superclasses (?@superclasses)> |
862 | |
863 | This is a read-write attribute which represents the superclass |
a2e85e6c |
864 | relationships of the class the B<Class::MOP::Class> instance is |
865 | associated with. Basically, it can get and set the C<@ISA> for you. |
552e3d24 |
866 | |
343203ee |
867 | B<NOTE:> |
868 | Perl will occasionally perform some C<@ISA> and method caching, if |
869 | you decide to change your superclass relationship at runtime (which |
870 | is quite insane and very much not recommened), then you should be |
871 | aware of this and the fact that this module does not make any |
872 | attempt to address this issue. |
873 | |
552e3d24 |
874 | =item B<class_precedence_list> |
875 | |
a2e85e6c |
876 | This computes the a list of all the class's ancestors in the same order |
877 | in which method dispatch will be done. This is similair to |
878 | what B<Class::ISA::super_path> does, but we don't remove duplicate names. |
552e3d24 |
879 | |
880 | =back |
881 | |
882 | =head2 Methods |
883 | |
884 | =over 4 |
885 | |
2e41896e |
886 | =item B<method_metaclass> |
887 | |
552e3d24 |
888 | =item B<add_method ($method_name, $method)> |
889 | |
890 | This will take a C<$method_name> and CODE reference to that |
a2e85e6c |
891 | C<$method> and install it into the class's package. |
552e3d24 |
892 | |
a2e85e6c |
893 | B<NOTE>: |
894 | This does absolutely nothing special to C<$method> |
552e3d24 |
895 | other than use B<Sub::Name> to make sure it is tagged with the |
896 | correct name, and therefore show up correctly in stack traces and |
897 | such. |
898 | |
663f8198 |
899 | =item B<alias_method ($method_name, $method)> |
900 | |
901 | This will take a C<$method_name> and CODE reference to that |
902 | C<$method> and alias the method into the class's package. |
903 | |
904 | B<NOTE>: |
905 | Unlike C<add_method>, this will B<not> try to name the |
906 | C<$method> using B<Sub::Name>, it only aliases the method in |
907 | the class's package. |
908 | |
552e3d24 |
909 | =item B<has_method ($method_name)> |
910 | |
a2e85e6c |
911 | This just provides a simple way to check if the class implements |
552e3d24 |
912 | a specific C<$method_name>. It will I<not> however, attempt to check |
a2e85e6c |
913 | if the class inherits the method (use C<UNIVERSAL::can> for that). |
552e3d24 |
914 | |
915 | This will correctly handle functions defined outside of the package |
916 | that use a fully qualified name (C<sub Package::name { ... }>). |
917 | |
918 | This will correctly handle functions renamed with B<Sub::Name> and |
919 | installed using the symbol tables. However, if you are naming the |
920 | subroutine outside of the package scope, you must use the fully |
921 | qualified name, including the package name, for C<has_method> to |
922 | correctly identify it. |
923 | |
924 | This will attempt to correctly ignore functions imported from other |
925 | packages using B<Exporter>. It breaks down if the function imported |
926 | is an C<__ANON__> sub (such as with C<use constant>), which very well |
927 | may be a valid method being applied to the class. |
928 | |
929 | In short, this method cannot always be trusted to determine if the |
930 | C<$method_name> is actually a method. However, it will DWIM about |
a2e85e6c |
931 | 90% of the time, so it's a small trade off I think. |
552e3d24 |
932 | |
933 | =item B<get_method ($method_name)> |
934 | |
935 | This will return a CODE reference of the specified C<$method_name>, |
936 | or return undef if that method does not exist. |
937 | |
938 | =item B<remove_method ($method_name)> |
939 | |
a2e85e6c |
940 | This will attempt to remove a given C<$method_name> from the class. |
552e3d24 |
941 | It will return the CODE reference that it has removed, and will |
942 | attempt to use B<Sub::Name> to clear the methods associated name. |
943 | |
944 | =item B<get_method_list> |
945 | |
946 | This will return a list of method names for all I<locally> defined |
947 | methods. It does B<not> provide a list of all applicable methods, |
948 | including any inherited ones. If you want a list of all applicable |
949 | methods, use the C<compute_all_applicable_methods> method. |
950 | |
951 | =item B<compute_all_applicable_methods> |
952 | |
a2e85e6c |
953 | This will return a list of all the methods names this class will |
954 | respond to, taking into account inheritance. The list will be a list of |
552e3d24 |
955 | HASH references, each one containing the following information; method |
956 | name, the name of the class in which the method lives and a CODE |
957 | reference for the actual method. |
958 | |
959 | =item B<find_all_methods_by_name ($method_name)> |
960 | |
961 | This will traverse the inheritence hierarchy and locate all methods |
962 | with a given C<$method_name>. Similar to |
963 | C<compute_all_applicable_methods> it returns a list of HASH references |
964 | with the following information; method name (which will always be the |
965 | same as C<$method_name>), the name of the class in which the method |
966 | lives and a CODE reference for the actual method. |
967 | |
968 | The list of methods produced is a distinct list, meaning there are no |
969 | duplicates in it. This is especially useful for things like object |
970 | initialization and destruction where you only want the method called |
971 | once, and in the correct order. |
972 | |
96ceced8 |
973 | =item B<find_next_method_by_name ($method_name)> |
974 | |
975 | This will return the first method to match a given C<$method_name> in |
976 | the superclasses, this is basically equivalent to calling |
977 | C<SUPER::$method_name>, but it can be dispatched at runtime. |
978 | |
552e3d24 |
979 | =back |
980 | |
a4258ffd |
981 | =head2 Method Modifiers |
982 | |
96ceced8 |
983 | Method modifiers are a concept borrowed from CLOS, in which a method |
984 | can be wrapped with I<before>, I<after> and I<around> method modifiers |
985 | that will be called everytime the method is called. |
986 | |
987 | =head3 How method modifiers work? |
988 | |
989 | Method modifiers work by wrapping the original method and then replacing |
990 | it in the classes symbol table. The wrappers will handle calling all the |
991 | modifiers in the appropariate orders and preserving the calling context |
992 | for the original method. |
993 | |
994 | Each method modifier serves a particular purpose, which may not be |
995 | obvious to users of other method wrapping modules. To start with, the |
996 | return values of I<before> and I<after> modifiers are ignored. This is |
997 | because thier purpose is B<not> to filter the input and output of the |
998 | primary method (this is done with an I<around> modifier). This may seem |
999 | like an odd restriction to some, but doing this allows for simple code |
1000 | to be added at the begining or end of a method call without jeapordizing |
1001 | the normal functioning of the primary method or placing any extra |
1002 | responsibility on the code of the modifier. Of course if you have more |
1003 | complex needs, then use the I<around> modifier, which uses a variation |
1004 | of continutation passing style to allow for a high degree of flexibility. |
1005 | |
1006 | Before and around modifiers are called in last-defined-first-called order, |
1007 | while after modifiers are called in first-defined-first-called order. So |
1008 | the call tree might looks something like this: |
1009 | |
1010 | before 2 |
1011 | before 1 |
1012 | around 2 |
1013 | around 1 |
1014 | primary |
1015 | after 1 |
1016 | after 2 |
1017 | |
1018 | To see examples of using method modifiers, see the following examples |
1019 | included in the distribution; F<InstanceCountingClass>, F<Perl6Attribute>, |
1020 | F<AttributesWithHistory> and F<C3MethodDispatchOrder>. There is also a |
1021 | classic CLOS usage example in the test F<017_add_method_modifier.t>. |
1022 | |
1023 | =head3 What is the performance impact? |
1024 | |
1025 | Of course there is a performance cost associated with method modifiers, |
1026 | but we have made every effort to make that cost be directly proportional |
1027 | to the amount of modifier features you utilize. |
1028 | |
1029 | The wrapping method does it's best to B<only> do as much work as it |
1030 | absolutely needs to. In order to do this we have moved some of the |
1031 | performance costs to set-up time, where they are easier to amortize. |
1032 | |
1033 | All this said, my benchmarks have indicated the following: |
1034 | |
1035 | simple wrapper with no modifiers 100% slower |
1036 | simple wrapper with simple before modifier 400% slower |
1037 | simple wrapper with simple after modifier 450% slower |
1038 | simple wrapper with simple around modifier 500-550% slower |
1039 | simple wrapper with all 3 modifiers 1100% slower |
1040 | |
1041 | These numbers may seem daunting, but you must remember, every feature |
1042 | comes with some cost. To put things in perspective, just doing a simple |
1043 | C<AUTOLOAD> which does nothing but extract the name of the method called |
1044 | and return it costs about 400% over a normal method call. |
1045 | |
a4258ffd |
1046 | =over 4 |
1047 | |
1048 | =item B<add_before_method_modifier ($method_name, $code)> |
1049 | |
96ceced8 |
1050 | This will wrap the method at C<$method_name> and the supplied C<$code> |
1051 | will be passed the C<@_> arguments, and called before the original |
1052 | method is called. As specified above, the return value of the I<before> |
1053 | method modifiers is ignored, and it's ability to modify C<@_> is |
1054 | fairly limited. If you need to do either of these things, use an |
1055 | C<around> method modifier. |
1056 | |
a4258ffd |
1057 | =item B<add_after_method_modifier ($method_name, $code)> |
1058 | |
96ceced8 |
1059 | This will wrap the method at C<$method_name> so that the original |
1060 | method will be called, it's return values stashed, and then the |
1061 | supplied C<$code> will be passed the C<@_> arguments, and called. |
1062 | As specified above, the return value of the I<after> method |
1063 | modifiers is ignored, and it cannot modify the return values of |
1064 | the original method. If you need to do either of these things, use an |
1065 | C<around> method modifier. |
1066 | |
a4258ffd |
1067 | =item B<add_around_method_modifier ($method_name, $code)> |
1068 | |
96ceced8 |
1069 | This will wrap the method at C<$method_name> so that C<$code> |
1070 | will be called and passed the original method as an extra argument |
1071 | at the begining of the C<@_> argument list. This is a variation of |
1072 | continuation passing style, where the function prepended to C<@_> |
1073 | can be considered a continuation. It is up to C<$code> if it calls |
1074 | the original method or not, there is no restriction on what the |
1075 | C<$code> can or cannot do. |
1076 | |
a4258ffd |
1077 | =back |
1078 | |
552e3d24 |
1079 | =head2 Attributes |
1080 | |
1081 | It should be noted that since there is no one consistent way to define |
1082 | the attributes of a class in Perl 5. These methods can only work with |
1083 | the information given, and can not easily discover information on |
a2e85e6c |
1084 | their own. See L<Class::MOP::Attribute> for more details. |
552e3d24 |
1085 | |
1086 | =over 4 |
1087 | |
2e41896e |
1088 | =item B<attribute_metaclass> |
1089 | |
7b31baf4 |
1090 | =item B<get_attribute_map> |
1091 | |
552e3d24 |
1092 | =item B<add_attribute ($attribute_name, $attribute_meta_object)> |
1093 | |
a2e85e6c |
1094 | This stores a C<$attribute_meta_object> in the B<Class::MOP::Class> |
1095 | instance associated with the given class, and associates it with |
1096 | the C<$attribute_name>. Unlike methods, attributes within the MOP |
1097 | are stored as meta-information only. They will be used later to |
1098 | construct instances from (see C<construct_instance> above). |
552e3d24 |
1099 | More details about the attribute meta-objects can be found in the |
a2e85e6c |
1100 | L<Class::MOP::Attribute> or the L<Class::MOP/The Attribute protocol> |
1101 | section. |
1102 | |
1103 | It should be noted that any accessor, reader/writer or predicate |
1104 | methods which the C<$attribute_meta_object> has will be installed |
1105 | into the class at this time. |
552e3d24 |
1106 | |
1107 | =item B<has_attribute ($attribute_name)> |
1108 | |
a2e85e6c |
1109 | Checks to see if this class has an attribute by the name of |
552e3d24 |
1110 | C<$attribute_name> and returns a boolean. |
1111 | |
1112 | =item B<get_attribute ($attribute_name)> |
1113 | |
1114 | Returns the attribute meta-object associated with C<$attribute_name>, |
1115 | if none is found, it will return undef. |
1116 | |
1117 | =item B<remove_attribute ($attribute_name)> |
1118 | |
1119 | This will remove the attribute meta-object stored at |
1120 | C<$attribute_name>, then return the removed attribute meta-object. |
1121 | |
a2e85e6c |
1122 | B<NOTE:> |
1123 | Removing an attribute will only affect future instances of |
552e3d24 |
1124 | the class, it will not make any attempt to remove the attribute from |
1125 | any existing instances of the class. |
1126 | |
a2e85e6c |
1127 | It should be noted that any accessor, reader/writer or predicate |
1128 | methods which the attribute meta-object stored at C<$attribute_name> |
1129 | has will be removed from the class at this time. This B<will> make |
1130 | these attributes somewhat inaccessable in previously created |
1131 | instances. But if you are crazy enough to do this at runtime, then |
1132 | you are crazy enough to deal with something like this :). |
1133 | |
552e3d24 |
1134 | =item B<get_attribute_list> |
1135 | |
1136 | This returns a list of attribute names which are defined in the local |
1137 | class. If you want a list of all applicable attributes for a class, |
1138 | use the C<compute_all_applicable_attributes> method. |
1139 | |
1140 | =item B<compute_all_applicable_attributes> |
1141 | |
c9e77dbb |
1142 | This will traverse the inheritance heirachy and return a list of all |
1143 | the applicable attributes for this class. It does not construct a |
1144 | HASH reference like C<compute_all_applicable_methods> because all |
1145 | that same information is discoverable through the attribute |
1146 | meta-object itself. |
552e3d24 |
1147 | |
058c1cf5 |
1148 | =item B<find_attribute_by_name ($attr_name)> |
1149 | |
1150 | This method will traverse the inheritance heirachy and find the |
1151 | first attribute whose name matches C<$attr_name>, then return it. |
1152 | It will return undef if nothing is found. |
1153 | |
552e3d24 |
1154 | =back |
1155 | |
52e8a34c |
1156 | =head2 Package Variables |
1157 | |
1158 | Since Perl's classes are built atop the Perl package system, it is |
1159 | fairly common to use package scoped variables for things like static |
1160 | class variables. The following methods are convience methods for |
1161 | the creation and inspection of package scoped variables. |
1162 | |
1163 | =over 4 |
1164 | |
1165 | =item B<add_package_variable ($variable_name, ?$initial_value)> |
1166 | |
1167 | Given a C<$variable_name>, which must contain a leading sigil, this |
1168 | method will create that variable within the package which houses the |
1169 | class. It also takes an optional C<$initial_value>, which must be a |
1170 | reference of the same type as the sigil of the C<$variable_name> |
1171 | implies. |
1172 | |
1173 | =item B<get_package_variable ($variable_name)> |
1174 | |
1175 | This will return a reference to the package variable in |
1176 | C<$variable_name>. |
1177 | |
1178 | =item B<has_package_variable ($variable_name)> |
1179 | |
1180 | Returns true (C<1>) if there is a package variable defined for |
1181 | C<$variable_name>, and false (C<0>) otherwise. |
1182 | |
1183 | =item B<remove_package_variable ($variable_name)> |
1184 | |
1185 | This will attempt to remove the package variable at C<$variable_name>. |
1186 | |
1187 | =back |
1188 | |
8b978dd5 |
1189 | =head1 AUTHOR |
1190 | |
a2e85e6c |
1191 | Stevan Little E<lt>stevan@iinteractive.comE<gt> |
8b978dd5 |
1192 | |
1193 | =head1 COPYRIGHT AND LICENSE |
1194 | |
1195 | Copyright 2006 by Infinity Interactive, Inc. |
1196 | |
1197 | L<http://www.iinteractive.com> |
1198 | |
1199 | This library is free software; you can redistribute it and/or modify |
1200 | it under the same terms as Perl itself. |
1201 | |
1202 | =cut |