Commit | Line | Data |
8b978dd5 |
1 | |
2 | package Class::MOP::Class; |
3 | |
4 | use strict; |
5 | use warnings; |
6 | |
c23184fc |
7 | use Class::MOP::Immutable; |
ba38bf08 |
8 | use Class::MOP::Instance; |
9 | use Class::MOP::Method::Wrapped; |
10 | |
8b978dd5 |
11 | use Carp 'confess'; |
77e5fce4 |
12 | use Scalar::Util 'blessed', 'reftype', 'weaken'; |
8b978dd5 |
13 | use Sub::Name 'subname'; |
96ceced8 |
14 | use B 'svref_2object'; |
8b978dd5 |
15 | |
823a5d31 |
16 | our $VERSION = '0.22'; |
f0480c45 |
17 | our $AUTHORITY = 'cpan:STEVAN'; |
8b978dd5 |
18 | |
2243a22b |
19 | use base 'Class::MOP::Module'; |
20 | |
aa448b16 |
21 | # Self-introspection |
2eb717d5 |
22 | |
aa448b16 |
23 | sub meta { Class::MOP::Class->initialize(blessed($_[0]) || $_[0]) } |
2eb717d5 |
24 | |
8b978dd5 |
25 | # Creation |
587aca23 |
26 | |
be7677c7 |
27 | sub initialize { |
28 | my $class = shift; |
29 | my $package_name = shift; |
30 | (defined $package_name && $package_name && !blessed($package_name)) |
31 | || confess "You must pass a package name and it cannot be blessed"; |
c23184fc |
32 | $class->construct_class_instance('package' => $package_name, @_); |
be7677c7 |
33 | } |
34 | |
35 | sub reinitialize { |
36 | my $class = shift; |
37 | my $package_name = shift; |
38 | (defined $package_name && $package_name && !blessed($package_name)) |
39 | || confess "You must pass a package name and it cannot be blessed"; |
40 | Class::MOP::remove_metaclass_by_name($package_name); |
c23184fc |
41 | $class->construct_class_instance('package' => $package_name, @_); |
be7677c7 |
42 | } |
651955fb |
43 | |
be7677c7 |
44 | # NOTE: (meta-circularity) |
45 | # this is a special form of &construct_instance |
46 | # (see below), which is used to construct class |
47 | # meta-object instances for any Class::MOP::* |
48 | # class. All other classes will use the more |
49 | # normal &construct_instance. |
50 | sub construct_class_instance { |
51 | my $class = shift; |
52 | my %options = @_; |
c23184fc |
53 | my $package_name = $options{'package'}; |
be7677c7 |
54 | (defined $package_name && $package_name) |
55 | || confess "You must pass a package name"; |
56 | # NOTE: |
57 | # return the metaclass if we have it cached, |
58 | # and it is still defined (it has not been |
59 | # reaped by DESTROY yet, which can happen |
60 | # annoyingly enough during global destruction) |
61 | return Class::MOP::get_metaclass_by_name($package_name) |
62 | if Class::MOP::does_metaclass_exist($package_name); |
63 | |
64 | # NOTE: |
65 | # we need to deal with the possibility |
66 | # of class immutability here, and then |
67 | # get the name of the class appropriately |
68 | $class = (blessed($class) |
69 | ? ($class->is_immutable |
70 | ? $class->get_mutable_metaclass_name() |
71 | : blessed($class)) |
72 | : $class); |
73 | |
be7677c7 |
74 | # now create the metaclass |
75 | my $meta; |
76 | if ($class =~ /^Class::MOP::Class$/) { |
77 | no strict 'refs'; |
78 | $meta = bless { |
79 | # inherited from Class::MOP::Package |
c23184fc |
80 | '$!package' => $package_name, |
c4260b45 |
81 | |
82 | # NOTE: |
83 | # since the following attributes will |
84 | # actually be loaded from the symbol |
85 | # table, and actually bypass the instance |
86 | # entirely, we can just leave these things |
87 | # listed here for reference, because they |
88 | # should not actually have a value associated |
89 | # with the slot. |
c23184fc |
90 | '%!namespace' => \undef, |
be7677c7 |
91 | # inherited from Class::MOP::Module |
c23184fc |
92 | '$!version' => \undef, |
93 | '$!authority' => \undef, |
c4260b45 |
94 | # defined in Class::MOP::Class |
c23184fc |
95 | '@!superclasses' => \undef, |
c4260b45 |
96 | |
c23184fc |
97 | '%!methods' => {}, |
98 | '%!attributes' => {}, |
99 | '$!attribute_metaclass' => $options{'attribute_metaclass'} || 'Class::MOP::Attribute', |
100 | '$!method_metaclass' => $options{'method_metaclass'} || 'Class::MOP::Method', |
101 | '$!instance_metaclass' => $options{'instance_metaclass'} || 'Class::MOP::Instance', |
be7677c7 |
102 | } => $class; |
103 | } |
104 | else { |
105 | # NOTE: |
106 | # it is safe to use meta here because |
107 | # class will always be a subclass of |
108 | # Class::MOP::Class, which defines meta |
109 | $meta = $class->meta->construct_instance(%options) |
727919c5 |
110 | } |
111 | |
be7677c7 |
112 | # and check the metaclass compatibility |
113 | $meta->check_metaclass_compatability(); |
ff43b9d6 |
114 | |
be7677c7 |
115 | Class::MOP::store_metaclass_by_name($package_name, $meta); |
b9d9fc0b |
116 | |
be7677c7 |
117 | # NOTE: |
118 | # we need to weaken any anon classes |
119 | # so that they can call DESTROY properly |
b9d9fc0b |
120 | Class::MOP::weaken_metaclass($package_name) if $meta->is_anon_class; |
121 | |
be7677c7 |
122 | $meta; |
123 | } |
124 | |
125 | sub check_metaclass_compatability { |
126 | my $self = shift; |
127 | |
128 | # this is always okay ... |
129 | return if blessed($self) eq 'Class::MOP::Class' && |
130 | $self->instance_metaclass eq 'Class::MOP::Instance'; |
131 | |
132 | my @class_list = $self->class_precedence_list; |
133 | shift @class_list; # shift off $self->name |
373a16ae |
134 | |
be7677c7 |
135 | foreach my $class_name (@class_list) { |
136 | my $meta = Class::MOP::get_metaclass_by_name($class_name) || next; |
137 | |
373a16ae |
138 | # NOTE: |
139 | # we need to deal with the possibility |
140 | # of class immutability here, and then |
be7677c7 |
141 | # get the name of the class appropriately |
142 | my $meta_type = ($meta->is_immutable |
143 | ? $meta->get_mutable_metaclass_name() |
144 | : blessed($meta)); |
145 | |
146 | ($self->isa($meta_type)) |
147 | || confess $self->name . "->meta => (" . (blessed($self)) . ")" . |
148 | " is not compatible with the " . |
149 | $class_name . "->meta => (" . ($meta_type) . ")"; |
77e5fce4 |
150 | # NOTE: |
be7677c7 |
151 | # we also need to check that instance metaclasses |
152 | # are compatabile in the same the class. |
153 | ($self->instance_metaclass->isa($meta->instance_metaclass)) |
154 | || confess $self->name . "->meta => (" . ($self->instance_metaclass) . ")" . |
155 | " is not compatible with the " . |
156 | $class_name . "->meta => (" . ($meta->instance_metaclass) . ")"; |
157 | } |
158 | } |
8b978dd5 |
159 | |
6d5355c3 |
160 | ## ANON classes |
161 | |
162 | { |
163 | # NOTE: |
164 | # this should be sufficient, if you have a |
165 | # use case where it is not, write a test and |
166 | # I will change it. |
167 | my $ANON_CLASS_SERIAL = 0; |
b9d9fc0b |
168 | |
169 | # NOTE: |
170 | # we need a sufficiently annoying prefix |
171 | # this should suffice for now, this is |
172 | # used in a couple of places below, so |
173 | # need to put it up here for now. |
174 | my $ANON_CLASS_PREFIX = 'Class::MOP::Class::__ANON__::SERIAL::'; |
175 | |
176 | sub is_anon_class { |
177 | my $self = shift; |
a651e249 |
178 | no warnings 'uninitialized'; |
b9d9fc0b |
179 | $self->name =~ /^$ANON_CLASS_PREFIX/ ? 1 : 0; |
180 | } |
6d5355c3 |
181 | |
182 | sub create_anon_class { |
183 | my ($class, %options) = @_; |
184 | my $package_name = $ANON_CLASS_PREFIX . ++$ANON_CLASS_SERIAL; |
88dd563c |
185 | return $class->create($package_name, %options); |
b9d9fc0b |
186 | } |
6d5355c3 |
187 | |
b9d9fc0b |
188 | # NOTE: |
189 | # this will only get called for |
190 | # anon-classes, all other calls |
191 | # are assumed to occur during |
192 | # global destruction and so don't |
193 | # really need to be handled explicitly |
194 | sub DESTROY { |
195 | my $self = shift; |
a651e249 |
196 | no warnings 'uninitialized'; |
b9d9fc0b |
197 | return unless $self->name =~ /^$ANON_CLASS_PREFIX/; |
198 | my ($serial_id) = ($self->name =~ /^$ANON_CLASS_PREFIX(\d+)/); |
199 | no strict 'refs'; |
200 | foreach my $key (keys %{$ANON_CLASS_PREFIX . $serial_id}) { |
201 | delete ${$ANON_CLASS_PREFIX . $serial_id}{$key}; |
202 | } |
203 | delete ${'main::' . $ANON_CLASS_PREFIX}{$serial_id . '::'}; |
6d5355c3 |
204 | } |
b9d9fc0b |
205 | |
6d5355c3 |
206 | } |
207 | |
208 | # creating classes with MOP ... |
209 | |
8b978dd5 |
210 | sub create { |
88dd563c |
211 | my $class = shift; |
212 | my $package_name = shift; |
213 | |
bfe4d0fc |
214 | (defined $package_name && $package_name) |
8b978dd5 |
215 | || confess "You must pass a package name"; |
88dd563c |
216 | |
217 | (scalar @_ % 2 == 0) |
218 | || confess "You much pass all parameters as name => value pairs " . |
219 | "(I found an uneven number of params in \@_)"; |
220 | |
221 | my (%options) = @_; |
222 | |
8b978dd5 |
223 | my $code = "package $package_name;"; |
88dd563c |
224 | $code .= "\$$package_name\:\:VERSION = '" . $options{version} . "';" |
225 | if exists $options{version}; |
226 | $code .= "\$$package_name\:\:AUTHORITY = '" . $options{authority} . "';" |
227 | if exists $options{authority}; |
228 | |
8b978dd5 |
229 | eval $code; |
230 | confess "creation of $package_name failed : $@" if $@; |
88dd563c |
231 | |
bfe4d0fc |
232 | my $meta = $class->initialize($package_name); |
aa448b16 |
233 | |
234 | $meta->add_method('meta' => sub { |
df7b4119 |
235 | $class->initialize(blessed($_[0]) || $_[0]); |
aa448b16 |
236 | }); |
237 | |
8b978dd5 |
238 | $meta->superclasses(@{$options{superclasses}}) |
239 | if exists $options{superclasses}; |
2eb717d5 |
240 | # NOTE: |
241 | # process attributes first, so that they can |
242 | # install accessors, but locally defined methods |
243 | # can then overwrite them. It is maybe a little odd, but |
244 | # I think this should be the order of things. |
245 | if (exists $options{attributes}) { |
cbd9f942 |
246 | foreach my $attr (@{$options{attributes}}) { |
247 | $meta->add_attribute($attr); |
2eb717d5 |
248 | } |
249 | } |
bfe4d0fc |
250 | if (exists $options{methods}) { |
251 | foreach my $method_name (keys %{$options{methods}}) { |
252 | $meta->add_method($method_name, $options{methods}->{$method_name}); |
253 | } |
2eb717d5 |
254 | } |
8b978dd5 |
255 | return $meta; |
256 | } |
257 | |
7b31baf4 |
258 | ## Attribute readers |
259 | |
260 | # NOTE: |
261 | # all these attribute readers will be bootstrapped |
262 | # away in the Class::MOP bootstrap section |
263 | |
c23184fc |
264 | sub get_attribute_map { $_[0]->{'%!attributes'} } |
265 | sub attribute_metaclass { $_[0]->{'$!attribute_metaclass'} } |
266 | sub method_metaclass { $_[0]->{'$!method_metaclass'} } |
267 | sub instance_metaclass { $_[0]->{'$!instance_metaclass'} } |
7b31baf4 |
268 | |
0f71bc80 |
269 | # FIXME: |
270 | # this is a prime canidate for conversion to XS |
7855ddba |
271 | sub get_method_map { |
c4260b45 |
272 | my $self = shift; |
c23184fc |
273 | my $map = $self->{'%!methods'}; |
0f71bc80 |
274 | |
275 | my $class_name = $self->name; |
276 | my $method_metaclass = $self->method_metaclass; |
277 | |
92330ee2 |
278 | foreach my $symbol ($self->list_all_package_symbols('CODE')) { |
91e0eb4a |
279 | my $code = $self->get_package_symbol('&' . $symbol); |
0f71bc80 |
280 | |
b9575695 |
281 | next if exists $map->{$symbol} && |
282 | defined $map->{$symbol} && |
283 | $map->{$symbol}->body == $code; |
0f71bc80 |
284 | |
285 | my $gv = svref_2object($code)->GV; |
286 | next if ($gv->STASH->NAME || '') ne $class_name && |
287 | ($gv->NAME || '') ne '__ANON__'; |
288 | |
289 | $map->{$symbol} = $method_metaclass->wrap($code); |
7855ddba |
290 | } |
0f71bc80 |
291 | |
7855ddba |
292 | return $map; |
c4260b45 |
293 | } |
294 | |
c9e77dbb |
295 | # Instance Construction & Cloning |
296 | |
5f3c057a |
297 | sub new_object { |
298 | my $class = shift; |
651955fb |
299 | # NOTE: |
300 | # we need to protect the integrity of the |
301 | # Class::MOP::Class singletons here, so we |
302 | # delegate this to &construct_class_instance |
303 | # which will deal with the singletons |
304 | return $class->construct_class_instance(@_) |
305 | if $class->name->isa('Class::MOP::Class'); |
24869f62 |
306 | return $class->construct_instance(@_); |
5f3c057a |
307 | } |
e16da3e6 |
308 | |
309 | sub construct_instance { |
cbd9f942 |
310 | my ($class, %params) = @_; |
0e76a376 |
311 | my $meta_instance = $class->get_meta_instance(); |
312 | my $instance = $meta_instance->create_instance(); |
c9e77dbb |
313 | foreach my $attr ($class->compute_all_applicable_attributes()) { |
f892c0f0 |
314 | $attr->initialize_instance_slot($meta_instance, $instance, \%params); |
cbd9f942 |
315 | } |
2d711cc8 |
316 | return $instance; |
317 | } |
318 | |
319 | sub get_meta_instance { |
320 | my $class = shift; |
052c2a1a |
321 | return $class->instance_metaclass->new( |
322 | $class, |
323 | $class->compute_all_applicable_attributes() |
324 | ); |
e16da3e6 |
325 | } |
326 | |
5f3c057a |
327 | sub clone_object { |
328 | my $class = shift; |
7b31baf4 |
329 | my $instance = shift; |
651955fb |
330 | (blessed($instance) && $instance->isa($class->name)) |
331 | || confess "You must pass an instance ($instance) of the metaclass (" . $class->name . ")"; |
332 | # NOTE: |
333 | # we need to protect the integrity of the |
334 | # Class::MOP::Class singletons here, they |
a740253a |
335 | # should not be cloned. |
651955fb |
336 | return $instance if $instance->isa('Class::MOP::Class'); |
f7259199 |
337 | $class->clone_instance($instance, @_); |
5f3c057a |
338 | } |
339 | |
c9e77dbb |
340 | sub clone_instance { |
651955fb |
341 | my ($class, $instance, %params) = @_; |
342 | (blessed($instance)) |
c9e77dbb |
343 | || confess "You can only clone instances, \$self is not a blessed instance"; |
f7259199 |
344 | my $meta_instance = $class->get_meta_instance(); |
c23184fc |
345 | my $clone = $meta_instance->clone_instance($instance); |
346 | foreach my $attr ($class->compute_all_applicable_attributes()) { |
347 | if ($params{$attr->init_arg}) { |
348 | $meta_instance->set_slot_value($clone, $attr->name, $params{$attr->init_arg}); |
349 | } |
350 | } |
c9e77dbb |
351 | return $clone; |
352 | } |
353 | |
8b978dd5 |
354 | # Inheritance |
355 | |
356 | sub superclasses { |
357 | my $self = shift; |
8b978dd5 |
358 | if (@_) { |
359 | my @supers = @_; |
9d6dce77 |
360 | @{$self->get_package_symbol('@ISA')} = @supers; |
d82060fe |
361 | # NOTE: |
362 | # we need to check the metaclass |
363 | # compatability here so that we can |
364 | # be sure that the superclass is |
365 | # not potentially creating an issues |
366 | # we don't know about |
367 | $self->check_metaclass_compatability(); |
8b978dd5 |
368 | } |
9d6dce77 |
369 | @{$self->get_package_symbol('@ISA')}; |
8b978dd5 |
370 | } |
371 | |
372 | sub class_precedence_list { |
373 | my $self = shift; |
bfe4d0fc |
374 | # NOTE: |
375 | # We need to check for ciruclar inheirtance here. |
376 | # This will do nothing if all is well, and blow |
377 | # up otherwise. Yes, it's an ugly hack, better |
378 | # suggestions are welcome. |
93b4e576 |
379 | { ($self->name || return)->isa('This is a test for circular inheritance') } |
8c936afc |
380 | # ... and now back to our regularly scheduled program |
8b978dd5 |
381 | ( |
382 | $self->name, |
383 | map { |
f7259199 |
384 | $self->initialize($_)->class_precedence_list() |
8b978dd5 |
385 | } $self->superclasses() |
386 | ); |
387 | } |
388 | |
0882828e |
389 | ## Methods |
390 | |
391 | sub add_method { |
392 | my ($self, $method_name, $method) = @_; |
393 | (defined $method_name && $method_name) |
394 | || confess "You must define a method name"; |
2d711cc8 |
395 | |
7855ddba |
396 | my $body; |
7855ddba |
397 | if (blessed($method)) { |
92330ee2 |
398 | $body = $method->body; |
7855ddba |
399 | } |
92330ee2 |
400 | else { |
7855ddba |
401 | $body = $method; |
7855ddba |
402 | ('CODE' eq (reftype($body) || '')) |
403 | || confess "Your code block must be a CODE reference"; |
0f71bc80 |
404 | $method = $self->method_metaclass->wrap($body); |
7855ddba |
405 | } |
0f71bc80 |
406 | $self->get_method_map->{$method_name} = $method; |
7855ddba |
407 | |
408 | my $full_method_name = ($self->name . '::' . $method_name); |
409 | $self->add_package_symbol("&${method_name}" => subname $full_method_name => $body); |
0882828e |
410 | } |
411 | |
a4258ffd |
412 | { |
2d711cc8 |
413 | my $fetch_and_prepare_method = sub { |
414 | my ($self, $method_name) = @_; |
415 | # fetch it locally |
416 | my $method = $self->get_method($method_name); |
417 | # if we dont have local ... |
418 | unless ($method) { |
195f5bf8 |
419 | # try to find the next method |
420 | $method = $self->find_next_method_by_name($method_name); |
421 | # die if it does not exist |
422 | (defined $method) |
b9575695 |
423 | || confess "The method '$method_name' is not found in the inherience hierarchy for class " . $self->name; |
195f5bf8 |
424 | # and now make sure to wrap it |
425 | # even if it is already wrapped |
426 | # because we need a new sub ref |
2d711cc8 |
427 | $method = Class::MOP::Method::Wrapped->wrap($method); |
195f5bf8 |
428 | } |
429 | else { |
430 | # now make sure we wrap it properly |
431 | $method = Class::MOP::Method::Wrapped->wrap($method) |
432 | unless $method->isa('Class::MOP::Method::Wrapped'); |
433 | } |
434 | $self->add_method($method_name => $method); |
2d711cc8 |
435 | return $method; |
436 | }; |
437 | |
438 | sub add_before_method_modifier { |
439 | my ($self, $method_name, $method_modifier) = @_; |
440 | (defined $method_name && $method_name) |
441 | || confess "You must pass in a method name"; |
442 | my $method = $fetch_and_prepare_method->($self, $method_name); |
443 | $method->add_before_modifier(subname ':before' => $method_modifier); |
444 | } |
445 | |
446 | sub add_after_method_modifier { |
447 | my ($self, $method_name, $method_modifier) = @_; |
448 | (defined $method_name && $method_name) |
449 | || confess "You must pass in a method name"; |
450 | my $method = $fetch_and_prepare_method->($self, $method_name); |
451 | $method->add_after_modifier(subname ':after' => $method_modifier); |
452 | } |
453 | |
454 | sub add_around_method_modifier { |
455 | my ($self, $method_name, $method_modifier) = @_; |
456 | (defined $method_name && $method_name) |
457 | || confess "You must pass in a method name"; |
458 | my $method = $fetch_and_prepare_method->($self, $method_name); |
459 | $method->add_around_modifier(subname ':around' => $method_modifier); |
460 | } |
a4258ffd |
461 | |
8c936afc |
462 | # NOTE: |
463 | # the methods above used to be named like this: |
464 | # ${pkg}::${method}:(before|after|around) |
465 | # but this proved problematic when using one modifier |
466 | # to wrap multiple methods (something which is likely |
467 | # to happen pretty regularly IMO). So instead of naming |
468 | # it like this, I have chosen to just name them purely |
469 | # with their modifier names, like so: |
470 | # :(before|after|around) |
471 | # The fact is that in a stack trace, it will be fairly |
472 | # evident from the context what method they are attached |
473 | # to, and so don't need the fully qualified name. |
ee5e71d4 |
474 | } |
475 | |
663f8198 |
476 | sub alias_method { |
477 | my ($self, $method_name, $method) = @_; |
478 | (defined $method_name && $method_name) |
479 | || confess "You must define a method name"; |
de19f115 |
480 | |
0f71bc80 |
481 | my $body = (blessed($method) ? $method->body : $method); |
482 | ('CODE' eq (reftype($body) || '')) |
483 | || confess "Your code block must be a CODE reference"; |
7855ddba |
484 | |
485 | $self->add_package_symbol("&${method_name}" => $body); |
16e960bd |
486 | } |
487 | |
de19f115 |
488 | sub has_method { |
489 | my ($self, $method_name) = @_; |
490 | (defined $method_name && $method_name) |
491 | || confess "You must define a method name"; |
0882828e |
492 | |
0f71bc80 |
493 | return 0 unless exists $self->get_method_map->{$method_name}; |
de19f115 |
494 | return 1; |
0882828e |
495 | } |
496 | |
497 | sub get_method { |
c9b8b7f9 |
498 | my ($self, $method_name) = @_; |
0882828e |
499 | (defined $method_name && $method_name) |
500 | || confess "You must define a method name"; |
7855ddba |
501 | |
0f71bc80 |
502 | # NOTE: |
503 | # I don't really need this here, because |
504 | # if the method_map is missing a key it |
505 | # will just return undef for me now |
506 | # return unless $self->has_method($method_name); |
9d6dce77 |
507 | |
7855ddba |
508 | return $self->get_method_map->{$method_name}; |
c9b8b7f9 |
509 | } |
510 | |
511 | sub remove_method { |
512 | my ($self, $method_name) = @_; |
513 | (defined $method_name && $method_name) |
514 | || confess "You must define a method name"; |
515 | |
516 | my $removed_method = $self->get_method($method_name); |
517 | |
0f71bc80 |
518 | do { |
519 | $self->remove_package_symbol("&${method_name}"); |
520 | delete $self->get_method_map->{$method_name}; |
521 | } if defined $removed_method; |
7855ddba |
522 | |
c9b8b7f9 |
523 | return $removed_method; |
524 | } |
525 | |
526 | sub get_method_list { |
527 | my $self = shift; |
0f71bc80 |
528 | keys %{$self->get_method_map}; |
7855ddba |
529 | } |
530 | |
531 | sub find_method_by_name { |
532 | my ($self, $method_name) = @_; |
b9575695 |
533 | (defined $method_name && $method_name) |
534 | || confess "You must define a method name to find"; |
535 | # keep a record of what we have seen |
536 | # here, this will handle all the |
537 | # inheritence issues because we are |
538 | # using the &class_precedence_list |
539 | my %seen_class; |
540 | my @cpl = $self->class_precedence_list(); |
541 | foreach my $class (@cpl) { |
542 | next if $seen_class{$class}; |
543 | $seen_class{$class}++; |
544 | # fetch the meta-class ... |
545 | my $meta = $self->initialize($class); |
546 | return $meta->get_method($method_name) |
547 | if $meta->has_method($method_name); |
548 | } |
549 | return; |
a5eca695 |
550 | } |
551 | |
552 | sub compute_all_applicable_methods { |
553 | my $self = shift; |
554 | my @methods; |
555 | # keep a record of what we have seen |
556 | # here, this will handle all the |
557 | # inheritence issues because we are |
558 | # using the &class_precedence_list |
559 | my (%seen_class, %seen_method); |
560 | foreach my $class ($self->class_precedence_list()) { |
561 | next if $seen_class{$class}; |
562 | $seen_class{$class}++; |
563 | # fetch the meta-class ... |
564 | my $meta = $self->initialize($class); |
565 | foreach my $method_name ($meta->get_method_list()) { |
566 | next if exists $seen_method{$method_name}; |
567 | $seen_method{$method_name}++; |
568 | push @methods => { |
569 | name => $method_name, |
570 | class => $class, |
571 | code => $meta->get_method($method_name) |
572 | }; |
573 | } |
574 | } |
575 | return @methods; |
576 | } |
577 | |
a5eca695 |
578 | sub find_all_methods_by_name { |
579 | my ($self, $method_name) = @_; |
580 | (defined $method_name && $method_name) |
581 | || confess "You must define a method name to find"; |
582 | my @methods; |
583 | # keep a record of what we have seen |
584 | # here, this will handle all the |
585 | # inheritence issues because we are |
586 | # using the &class_precedence_list |
587 | my %seen_class; |
588 | foreach my $class ($self->class_precedence_list()) { |
589 | next if $seen_class{$class}; |
590 | $seen_class{$class}++; |
591 | # fetch the meta-class ... |
96ceced8 |
592 | my $meta = $self->initialize($class); |
a5eca695 |
593 | push @methods => { |
594 | name => $method_name, |
595 | class => $class, |
596 | code => $meta->get_method($method_name) |
597 | } if $meta->has_method($method_name); |
598 | } |
599 | return @methods; |
8b978dd5 |
600 | } |
601 | |
96ceced8 |
602 | sub find_next_method_by_name { |
603 | my ($self, $method_name) = @_; |
604 | (defined $method_name && $method_name) |
2d711cc8 |
605 | || confess "You must define a method name to find"; |
96ceced8 |
606 | # keep a record of what we have seen |
607 | # here, this will handle all the |
608 | # inheritence issues because we are |
609 | # using the &class_precedence_list |
610 | my %seen_class; |
2d711cc8 |
611 | my @cpl = $self->class_precedence_list(); |
612 | shift @cpl; # discard ourselves |
96ceced8 |
613 | foreach my $class (@cpl) { |
614 | next if $seen_class{$class}; |
615 | $seen_class{$class}++; |
616 | # fetch the meta-class ... |
617 | my $meta = $self->initialize($class); |
2d711cc8 |
618 | return $meta->get_method($method_name) |
619 | if $meta->has_method($method_name); |
96ceced8 |
620 | } |
2d711cc8 |
621 | return; |
96ceced8 |
622 | } |
623 | |
552e3d24 |
624 | ## Attributes |
625 | |
e16da3e6 |
626 | sub add_attribute { |
2e41896e |
627 | my $self = shift; |
628 | # either we have an attribute object already |
629 | # or we need to create one from the args provided |
630 | my $attribute = blessed($_[0]) ? $_[0] : $self->attribute_metaclass->new(@_); |
631 | # make sure it is derived from the correct type though |
632 | ($attribute->isa('Class::MOP::Attribute')) |
633 | || confess "Your attribute must be an instance of Class::MOP::Attribute (or a subclass)"; |
b1897d4d |
634 | |
635 | # first we attach our new attribute |
636 | # because it might need certain information |
637 | # about the class which it is attached to |
9ec169fe |
638 | $attribute->attach_to_class($self); |
b1897d4d |
639 | |
640 | # then we remove attributes of a conflicting |
641 | # name here so that we can properly detach |
642 | # the old attr object, and remove any |
643 | # accessors it would have generated |
644 | $self->remove_attribute($attribute->name) |
645 | if $self->has_attribute($attribute->name); |
646 | |
647 | # then onto installing the new accessors |
2d711cc8 |
648 | $attribute->install_accessors(); |
291073fc |
649 | $self->get_attribute_map->{$attribute->name} = $attribute; |
e16da3e6 |
650 | } |
651 | |
652 | sub has_attribute { |
653 | my ($self, $attribute_name) = @_; |
654 | (defined $attribute_name && $attribute_name) |
655 | || confess "You must define an attribute name"; |
291073fc |
656 | exists $self->get_attribute_map->{$attribute_name} ? 1 : 0; |
e16da3e6 |
657 | } |
658 | |
659 | sub get_attribute { |
660 | my ($self, $attribute_name) = @_; |
661 | (defined $attribute_name && $attribute_name) |
662 | || confess "You must define an attribute name"; |
f7259199 |
663 | return $self->get_attribute_map->{$attribute_name} |
b1897d4d |
664 | # NOTE: |
665 | # this will return undef anyway, so no need ... |
666 | # if $self->has_attribute($attribute_name); |
667 | #return; |
e16da3e6 |
668 | } |
669 | |
670 | sub remove_attribute { |
671 | my ($self, $attribute_name) = @_; |
672 | (defined $attribute_name && $attribute_name) |
673 | || confess "You must define an attribute name"; |
7b31baf4 |
674 | my $removed_attribute = $self->get_attribute_map->{$attribute_name}; |
22286063 |
675 | return unless defined $removed_attribute; |
676 | delete $self->get_attribute_map->{$attribute_name}; |
2d711cc8 |
677 | $removed_attribute->remove_accessors(); |
2d711cc8 |
678 | $removed_attribute->detach_from_class(); |
e16da3e6 |
679 | return $removed_attribute; |
680 | } |
681 | |
682 | sub get_attribute_list { |
683 | my $self = shift; |
f7259199 |
684 | keys %{$self->get_attribute_map}; |
e16da3e6 |
685 | } |
686 | |
687 | sub compute_all_applicable_attributes { |
688 | my $self = shift; |
689 | my @attrs; |
690 | # keep a record of what we have seen |
691 | # here, this will handle all the |
692 | # inheritence issues because we are |
693 | # using the &class_precedence_list |
694 | my (%seen_class, %seen_attr); |
695 | foreach my $class ($self->class_precedence_list()) { |
696 | next if $seen_class{$class}; |
697 | $seen_class{$class}++; |
698 | # fetch the meta-class ... |
f7259199 |
699 | my $meta = $self->initialize($class); |
e16da3e6 |
700 | foreach my $attr_name ($meta->get_attribute_list()) { |
701 | next if exists $seen_attr{$attr_name}; |
702 | $seen_attr{$attr_name}++; |
c9e77dbb |
703 | push @attrs => $meta->get_attribute($attr_name); |
e16da3e6 |
704 | } |
705 | } |
706 | return @attrs; |
707 | } |
2eb717d5 |
708 | |
058c1cf5 |
709 | sub find_attribute_by_name { |
710 | my ($self, $attr_name) = @_; |
711 | # keep a record of what we have seen |
712 | # here, this will handle all the |
713 | # inheritence issues because we are |
714 | # using the &class_precedence_list |
715 | my %seen_class; |
716 | foreach my $class ($self->class_precedence_list()) { |
717 | next if $seen_class{$class}; |
718 | $seen_class{$class}++; |
719 | # fetch the meta-class ... |
720 | my $meta = $self->initialize($class); |
721 | return $meta->get_attribute($attr_name) |
722 | if $meta->has_attribute($attr_name); |
723 | } |
724 | return; |
725 | } |
726 | |
857f87a7 |
727 | ## Class closing |
728 | |
729 | sub is_mutable { 1 } |
730 | sub is_immutable { 0 } |
731 | |
c23184fc |
732 | { |
733 | # NOTE: |
734 | # the immutable version of a |
735 | # particular metaclass is |
736 | # really class-level data so |
737 | # we don't want to regenerate |
738 | # it any more than we need to |
739 | my $IMMUTABLE_METACLASS; |
740 | sub make_immutable { |
741 | my ($self) = @_; |
742 | |
743 | $IMMUTABLE_METACLASS ||= Class::MOP::Immutable->new($self, { |
744 | read_only => [qw/superclasses/], |
745 | cannot_call => [qw/ |
746 | add_method |
747 | alias_method |
748 | remove_method |
749 | add_attribute |
750 | remove_attribute |
751 | add_package_symbol |
752 | remove_package_symbol |
753 | /], |
754 | memoize => { |
755 | class_precedence_list => 'ARRAY', |
756 | compute_all_applicable_attributes => 'ARRAY', |
757 | get_meta_instance => 'SCALAR', |
758 | get_method_map => 'SCALAR', |
759 | } |
760 | }); |
761 | |
762 | $IMMUTABLE_METACLASS->make_metaclass_immutable(@_) |
763 | } |
857f87a7 |
764 | } |
765 | |
8b978dd5 |
766 | 1; |
767 | |
768 | __END__ |
769 | |
770 | =pod |
771 | |
772 | =head1 NAME |
773 | |
774 | Class::MOP::Class - Class Meta Object |
775 | |
776 | =head1 SYNOPSIS |
777 | |
8c936afc |
778 | # assuming that class Foo |
779 | # has been defined, you can |
780 | |
fe122940 |
781 | # use this for introspection ... |
782 | |
fe122940 |
783 | # add a method to Foo ... |
784 | Foo->meta->add_method('bar' => sub { ... }) |
785 | |
786 | # get a list of all the classes searched |
787 | # the method dispatcher in the correct order |
788 | Foo->meta->class_precedence_list() |
789 | |
790 | # remove a method from Foo |
791 | Foo->meta->remove_method('bar'); |
792 | |
793 | # or use this to actually create classes ... |
794 | |
88dd563c |
795 | Class::MOP::Class->create('Bar' => ( |
796 | version => '0.01', |
fe122940 |
797 | superclasses => [ 'Foo' ], |
798 | attributes => [ |
799 | Class::MOP:::Attribute->new('$bar'), |
800 | Class::MOP:::Attribute->new('$baz'), |
801 | ], |
802 | methods => { |
803 | calculate_bar => sub { ... }, |
804 | construct_baz => sub { ... } |
805 | } |
806 | )); |
807 | |
8b978dd5 |
808 | =head1 DESCRIPTION |
809 | |
fe122940 |
810 | This is the largest and currently most complex part of the Perl 5 |
811 | meta-object protocol. It controls the introspection and |
812 | manipulation of Perl 5 classes (and it can create them too). The |
813 | best way to understand what this module can do, is to read the |
814 | documentation for each of it's methods. |
815 | |
552e3d24 |
816 | =head1 METHODS |
817 | |
2eb717d5 |
818 | =head2 Self Introspection |
819 | |
820 | =over 4 |
821 | |
822 | =item B<meta> |
823 | |
fe122940 |
824 | This will return a B<Class::MOP::Class> instance which is related |
825 | to this class. Thereby allowing B<Class::MOP::Class> to actually |
826 | introspect itself. |
827 | |
828 | As with B<Class::MOP::Attribute>, B<Class::MOP> will actually |
829 | bootstrap this module by installing a number of attribute meta-objects |
830 | into it's metaclass. This will allow this class to reap all the benifits |
831 | of the MOP when subclassing it. |
2eb717d5 |
832 | |
833 | =back |
834 | |
552e3d24 |
835 | =head2 Class construction |
836 | |
a2e85e6c |
837 | These methods will handle creating B<Class::MOP::Class> objects, |
838 | which can be used to both create new classes, and analyze |
839 | pre-existing classes. |
552e3d24 |
840 | |
841 | This module will internally store references to all the instances |
842 | you create with these methods, so that they do not need to be |
843 | created any more than nessecary. Basically, they are singletons. |
844 | |
845 | =over 4 |
846 | |
88dd563c |
847 | =item B<create ($package_name, |
848 | version =E<gt> ?$version, |
849 | authority =E<gt> ?$authority, |
a2e85e6c |
850 | superclasses =E<gt> ?@superclasses, |
851 | methods =E<gt> ?%methods, |
852 | attributes =E<gt> ?%attributes)> |
552e3d24 |
853 | |
a2e85e6c |
854 | This returns a B<Class::MOP::Class> object, bringing the specified |
88dd563c |
855 | C<$package_name> into existence and adding any of the C<$version>, |
856 | C<$authority>, C<@superclasses>, C<%methods> and C<%attributes> to |
857 | it. |
552e3d24 |
858 | |
587aca23 |
859 | =item B<create_anon_class (superclasses =E<gt> ?@superclasses, |
860 | methods =E<gt> ?%methods, |
861 | attributes =E<gt> ?%attributes)> |
862 | |
863 | This will create an anonymous class, it works much like C<create> but |
864 | it does not need a C<$package_name>. Instead it will create a suitably |
865 | unique package name for you to stash things into. |
866 | |
823a5d31 |
867 | On very important distinction is that anon classes are destroyed once |
868 | the metaclass they are attached to goes out of scope. In the DESTROY |
869 | method, the created package will be removed from the symbol table. |
870 | |
66b3dded |
871 | =item B<initialize ($package_name, %options)> |
552e3d24 |
872 | |
a2e85e6c |
873 | This initializes and returns returns a B<Class::MOP::Class> object |
874 | for a given a C<$package_name>. |
875 | |
66b3dded |
876 | =item B<reinitialize ($package_name, %options)> |
877 | |
878 | This removes the old metaclass, and creates a new one in it's place. |
879 | Do B<not> use this unless you really know what you are doing, it could |
880 | very easily make a very large mess of your program. |
881 | |
651955fb |
882 | =item B<construct_class_instance (%options)> |
a2e85e6c |
883 | |
884 | This will construct an instance of B<Class::MOP::Class>, it is |
885 | here so that we can actually "tie the knot" for B<Class::MOP::Class> |
886 | to use C<construct_instance> once all the bootstrapping is done. This |
887 | method is used internally by C<initialize> and should never be called |
888 | from outside of that method really. |
552e3d24 |
889 | |
550d56db |
890 | =item B<check_metaclass_compatability> |
891 | |
892 | This method is called as the very last thing in the |
893 | C<construct_class_instance> method. This will check that the |
894 | metaclass you are creating is compatible with the metaclasses of all |
895 | your ancestors. For more inforamtion about metaclass compatibility |
896 | see the C<About Metaclass compatibility> section in L<Class::MOP>. |
897 | |
552e3d24 |
898 | =back |
899 | |
c9e77dbb |
900 | =head2 Object instance construction and cloning |
a2e85e6c |
901 | |
c9e77dbb |
902 | These methods are B<entirely optional>, it is up to you whether you want |
903 | to use them or not. |
552e3d24 |
904 | |
905 | =over 4 |
906 | |
2bab2be6 |
907 | =item B<instance_metaclass> |
908 | |
2d711cc8 |
909 | =item B<get_meta_instance> |
910 | |
5f3c057a |
911 | =item B<new_object (%params)> |
912 | |
913 | This is a convience method for creating a new object of the class, and |
914 | blessing it into the appropriate package as well. Ideally your class |
915 | would call a C<new> this method like so: |
916 | |
917 | sub MyClass::new { |
918 | my ($class, %param) = @_; |
919 | $class->meta->new_object(%params); |
920 | } |
921 | |
922 | Of course the ideal place for this would actually be in C<UNIVERSAL::> |
923 | but that is considered bad style, so we do not do that. |
924 | |
cbd9f942 |
925 | =item B<construct_instance (%params)> |
552e3d24 |
926 | |
c9e77dbb |
927 | This method is used to construct an instace structure suitable for |
928 | C<bless>-ing into your package of choice. It works in conjunction |
929 | with the Attribute protocol to collect all applicable attributes. |
930 | |
cbd9f942 |
931 | This will construct and instance using a HASH ref as storage |
552e3d24 |
932 | (currently only HASH references are supported). This will collect all |
a2e85e6c |
933 | the applicable attributes and layout out the fields in the HASH ref, |
934 | it will then initialize them using either use the corresponding key |
935 | in C<%params> or any default value or initializer found in the |
936 | attribute meta-object. |
727919c5 |
937 | |
5f3c057a |
938 | =item B<clone_object ($instance, %params)> |
939 | |
940 | This is a convience method for cloning an object instance, then |
19d4b5b8 |
941 | blessing it into the appropriate package. This method will call |
942 | C<clone_instance>, which performs a shallow copy of the object, |
943 | see that methods documentation for more details. Ideally your |
944 | class would call a C<clone> this method like so: |
5f3c057a |
945 | |
946 | sub MyClass::clone { |
947 | my ($self, %param) = @_; |
948 | $self->meta->clone_object($self, %params); |
949 | } |
950 | |
951 | Of course the ideal place for this would actually be in C<UNIVERSAL::> |
952 | but that is considered bad style, so we do not do that. |
953 | |
c9e77dbb |
954 | =item B<clone_instance($instance, %params)> |
955 | |
956 | This method is a compliment of C<construct_instance> (which means if |
19d4b5b8 |
957 | you override C<construct_instance>, you need to override this one too), |
958 | and clones the instance shallowly. |
a27ae83f |
959 | |
960 | The cloned structure returned is (like with C<construct_instance>) an |
961 | unC<bless>ed HASH reference, it is your responsibility to then bless |
962 | this cloned structure into the right class (which C<clone_object> will |
963 | do for you). |
c9e77dbb |
964 | |
19d4b5b8 |
965 | As of 0.11, this method will clone the C<$instance> structure shallowly, |
966 | as opposed to the deep cloning implemented in prior versions. After much |
967 | thought, research and discussion, I have decided that anything but basic |
968 | shallow cloning is outside the scope of the meta-object protocol. I |
969 | think Yuval "nothingmuch" Kogman put it best when he said that cloning |
970 | is too I<context-specific> to be part of the MOP. |
971 | |
552e3d24 |
972 | =back |
973 | |
974 | =head2 Informational |
975 | |
b9d9fc0b |
976 | These are a few predicate methods for asking information about the class. |
552e3d24 |
977 | |
b9d9fc0b |
978 | =over 4 |
552e3d24 |
979 | |
b9d9fc0b |
980 | =item B<is_anon_class> |
552e3d24 |
981 | |
96e38ba6 |
982 | This returns true if the class is a C<Class::MOP::Class> created anon class. |
983 | |
b9d9fc0b |
984 | =item B<is_mutable> |
552e3d24 |
985 | |
96e38ba6 |
986 | This returns true if the class is still mutable. |
987 | |
b9d9fc0b |
988 | =item B<is_immutable> |
552e3d24 |
989 | |
96e38ba6 |
990 | This returns true if the class has been made immutable. |
991 | |
552e3d24 |
992 | =back |
993 | |
994 | =head2 Inheritance Relationships |
995 | |
996 | =over 4 |
997 | |
998 | =item B<superclasses (?@superclasses)> |
999 | |
1000 | This is a read-write attribute which represents the superclass |
a2e85e6c |
1001 | relationships of the class the B<Class::MOP::Class> instance is |
1002 | associated with. Basically, it can get and set the C<@ISA> for you. |
552e3d24 |
1003 | |
343203ee |
1004 | B<NOTE:> |
1005 | Perl will occasionally perform some C<@ISA> and method caching, if |
1006 | you decide to change your superclass relationship at runtime (which |
1007 | is quite insane and very much not recommened), then you should be |
1008 | aware of this and the fact that this module does not make any |
1009 | attempt to address this issue. |
1010 | |
552e3d24 |
1011 | =item B<class_precedence_list> |
1012 | |
a2e85e6c |
1013 | This computes the a list of all the class's ancestors in the same order |
1014 | in which method dispatch will be done. This is similair to |
1015 | what B<Class::ISA::super_path> does, but we don't remove duplicate names. |
552e3d24 |
1016 | |
1017 | =back |
1018 | |
1019 | =head2 Methods |
1020 | |
1021 | =over 4 |
1022 | |
c4260b45 |
1023 | =item B<get_method_map> |
1024 | |
2e41896e |
1025 | =item B<method_metaclass> |
1026 | |
552e3d24 |
1027 | =item B<add_method ($method_name, $method)> |
1028 | |
1029 | This will take a C<$method_name> and CODE reference to that |
a2e85e6c |
1030 | C<$method> and install it into the class's package. |
552e3d24 |
1031 | |
a2e85e6c |
1032 | B<NOTE>: |
1033 | This does absolutely nothing special to C<$method> |
552e3d24 |
1034 | other than use B<Sub::Name> to make sure it is tagged with the |
1035 | correct name, and therefore show up correctly in stack traces and |
1036 | such. |
1037 | |
663f8198 |
1038 | =item B<alias_method ($method_name, $method)> |
1039 | |
1040 | This will take a C<$method_name> and CODE reference to that |
1041 | C<$method> and alias the method into the class's package. |
1042 | |
1043 | B<NOTE>: |
1044 | Unlike C<add_method>, this will B<not> try to name the |
1045 | C<$method> using B<Sub::Name>, it only aliases the method in |
1046 | the class's package. |
1047 | |
552e3d24 |
1048 | =item B<has_method ($method_name)> |
1049 | |
a2e85e6c |
1050 | This just provides a simple way to check if the class implements |
552e3d24 |
1051 | a specific C<$method_name>. It will I<not> however, attempt to check |
a2e85e6c |
1052 | if the class inherits the method (use C<UNIVERSAL::can> for that). |
552e3d24 |
1053 | |
1054 | This will correctly handle functions defined outside of the package |
1055 | that use a fully qualified name (C<sub Package::name { ... }>). |
1056 | |
1057 | This will correctly handle functions renamed with B<Sub::Name> and |
1058 | installed using the symbol tables. However, if you are naming the |
1059 | subroutine outside of the package scope, you must use the fully |
1060 | qualified name, including the package name, for C<has_method> to |
1061 | correctly identify it. |
1062 | |
1063 | This will attempt to correctly ignore functions imported from other |
1064 | packages using B<Exporter>. It breaks down if the function imported |
1065 | is an C<__ANON__> sub (such as with C<use constant>), which very well |
1066 | may be a valid method being applied to the class. |
1067 | |
1068 | In short, this method cannot always be trusted to determine if the |
1069 | C<$method_name> is actually a method. However, it will DWIM about |
a2e85e6c |
1070 | 90% of the time, so it's a small trade off I think. |
552e3d24 |
1071 | |
1072 | =item B<get_method ($method_name)> |
1073 | |
86482605 |
1074 | This will return a Class::MOP::Method instance related to the specified |
1075 | C<$method_name>, or return undef if that method does not exist. |
1076 | |
1077 | The Class::MOP::Method is codifiable, so you can use it like a normal |
1078 | CODE reference, see L<Class::MOP::Method> for more information. |
552e3d24 |
1079 | |
16e960bd |
1080 | =item B<find_method_by_name ($method_name> |
1081 | |
1082 | This will return a CODE reference of the specified C<$method_name>, |
1083 | or return undef if that method does not exist. |
1084 | |
1085 | Unlike C<get_method> this will also look in the superclasses. |
1086 | |
552e3d24 |
1087 | =item B<remove_method ($method_name)> |
1088 | |
a2e85e6c |
1089 | This will attempt to remove a given C<$method_name> from the class. |
552e3d24 |
1090 | It will return the CODE reference that it has removed, and will |
1091 | attempt to use B<Sub::Name> to clear the methods associated name. |
1092 | |
1093 | =item B<get_method_list> |
1094 | |
1095 | This will return a list of method names for all I<locally> defined |
1096 | methods. It does B<not> provide a list of all applicable methods, |
1097 | including any inherited ones. If you want a list of all applicable |
1098 | methods, use the C<compute_all_applicable_methods> method. |
1099 | |
1100 | =item B<compute_all_applicable_methods> |
1101 | |
a2e85e6c |
1102 | This will return a list of all the methods names this class will |
1103 | respond to, taking into account inheritance. The list will be a list of |
552e3d24 |
1104 | HASH references, each one containing the following information; method |
1105 | name, the name of the class in which the method lives and a CODE |
1106 | reference for the actual method. |
1107 | |
1108 | =item B<find_all_methods_by_name ($method_name)> |
1109 | |
1110 | This will traverse the inheritence hierarchy and locate all methods |
1111 | with a given C<$method_name>. Similar to |
1112 | C<compute_all_applicable_methods> it returns a list of HASH references |
1113 | with the following information; method name (which will always be the |
1114 | same as C<$method_name>), the name of the class in which the method |
1115 | lives and a CODE reference for the actual method. |
1116 | |
1117 | The list of methods produced is a distinct list, meaning there are no |
1118 | duplicates in it. This is especially useful for things like object |
1119 | initialization and destruction where you only want the method called |
1120 | once, and in the correct order. |
1121 | |
96ceced8 |
1122 | =item B<find_next_method_by_name ($method_name)> |
1123 | |
1124 | This will return the first method to match a given C<$method_name> in |
1125 | the superclasses, this is basically equivalent to calling |
1126 | C<SUPER::$method_name>, but it can be dispatched at runtime. |
1127 | |
552e3d24 |
1128 | =back |
1129 | |
a4258ffd |
1130 | =head2 Method Modifiers |
1131 | |
96ceced8 |
1132 | Method modifiers are a concept borrowed from CLOS, in which a method |
1133 | can be wrapped with I<before>, I<after> and I<around> method modifiers |
1134 | that will be called everytime the method is called. |
1135 | |
1136 | =head3 How method modifiers work? |
1137 | |
1138 | Method modifiers work by wrapping the original method and then replacing |
1139 | it in the classes symbol table. The wrappers will handle calling all the |
1140 | modifiers in the appropariate orders and preserving the calling context |
1141 | for the original method. |
1142 | |
1143 | Each method modifier serves a particular purpose, which may not be |
1144 | obvious to users of other method wrapping modules. To start with, the |
1145 | return values of I<before> and I<after> modifiers are ignored. This is |
1146 | because thier purpose is B<not> to filter the input and output of the |
1147 | primary method (this is done with an I<around> modifier). This may seem |
1148 | like an odd restriction to some, but doing this allows for simple code |
1149 | to be added at the begining or end of a method call without jeapordizing |
1150 | the normal functioning of the primary method or placing any extra |
1151 | responsibility on the code of the modifier. Of course if you have more |
1152 | complex needs, then use the I<around> modifier, which uses a variation |
1153 | of continutation passing style to allow for a high degree of flexibility. |
1154 | |
1155 | Before and around modifiers are called in last-defined-first-called order, |
1156 | while after modifiers are called in first-defined-first-called order. So |
1157 | the call tree might looks something like this: |
1158 | |
1159 | before 2 |
1160 | before 1 |
1161 | around 2 |
1162 | around 1 |
1163 | primary |
1164 | after 1 |
1165 | after 2 |
1166 | |
1167 | To see examples of using method modifiers, see the following examples |
1168 | included in the distribution; F<InstanceCountingClass>, F<Perl6Attribute>, |
1169 | F<AttributesWithHistory> and F<C3MethodDispatchOrder>. There is also a |
1170 | classic CLOS usage example in the test F<017_add_method_modifier.t>. |
1171 | |
1172 | =head3 What is the performance impact? |
1173 | |
1174 | Of course there is a performance cost associated with method modifiers, |
1175 | but we have made every effort to make that cost be directly proportional |
1176 | to the amount of modifier features you utilize. |
1177 | |
1178 | The wrapping method does it's best to B<only> do as much work as it |
1179 | absolutely needs to. In order to do this we have moved some of the |
1180 | performance costs to set-up time, where they are easier to amortize. |
1181 | |
1182 | All this said, my benchmarks have indicated the following: |
1183 | |
1184 | simple wrapper with no modifiers 100% slower |
1185 | simple wrapper with simple before modifier 400% slower |
1186 | simple wrapper with simple after modifier 450% slower |
1187 | simple wrapper with simple around modifier 500-550% slower |
1188 | simple wrapper with all 3 modifiers 1100% slower |
1189 | |
1190 | These numbers may seem daunting, but you must remember, every feature |
1191 | comes with some cost. To put things in perspective, just doing a simple |
1192 | C<AUTOLOAD> which does nothing but extract the name of the method called |
1193 | and return it costs about 400% over a normal method call. |
1194 | |
a4258ffd |
1195 | =over 4 |
1196 | |
1197 | =item B<add_before_method_modifier ($method_name, $code)> |
1198 | |
96ceced8 |
1199 | This will wrap the method at C<$method_name> and the supplied C<$code> |
1200 | will be passed the C<@_> arguments, and called before the original |
1201 | method is called. As specified above, the return value of the I<before> |
1202 | method modifiers is ignored, and it's ability to modify C<@_> is |
1203 | fairly limited. If you need to do either of these things, use an |
1204 | C<around> method modifier. |
1205 | |
a4258ffd |
1206 | =item B<add_after_method_modifier ($method_name, $code)> |
1207 | |
96ceced8 |
1208 | This will wrap the method at C<$method_name> so that the original |
1209 | method will be called, it's return values stashed, and then the |
1210 | supplied C<$code> will be passed the C<@_> arguments, and called. |
1211 | As specified above, the return value of the I<after> method |
1212 | modifiers is ignored, and it cannot modify the return values of |
1213 | the original method. If you need to do either of these things, use an |
1214 | C<around> method modifier. |
1215 | |
a4258ffd |
1216 | =item B<add_around_method_modifier ($method_name, $code)> |
1217 | |
96ceced8 |
1218 | This will wrap the method at C<$method_name> so that C<$code> |
1219 | will be called and passed the original method as an extra argument |
1220 | at the begining of the C<@_> argument list. This is a variation of |
1221 | continuation passing style, where the function prepended to C<@_> |
1222 | can be considered a continuation. It is up to C<$code> if it calls |
1223 | the original method or not, there is no restriction on what the |
1224 | C<$code> can or cannot do. |
1225 | |
a4258ffd |
1226 | =back |
1227 | |
552e3d24 |
1228 | =head2 Attributes |
1229 | |
1230 | It should be noted that since there is no one consistent way to define |
1231 | the attributes of a class in Perl 5. These methods can only work with |
1232 | the information given, and can not easily discover information on |
a2e85e6c |
1233 | their own. See L<Class::MOP::Attribute> for more details. |
552e3d24 |
1234 | |
1235 | =over 4 |
1236 | |
2e41896e |
1237 | =item B<attribute_metaclass> |
1238 | |
7b31baf4 |
1239 | =item B<get_attribute_map> |
1240 | |
8203616d |
1241 | =item B<add_attribute ($attribute_meta_object | $attribute_name, %attribute_spec)> |
552e3d24 |
1242 | |
8203616d |
1243 | This stores the C<$attribute_meta_object> (or creates one from the |
1244 | C<$attribute_name> and C<%attribute_spec>) in the B<Class::MOP::Class> |
1245 | instance associated with the given class. Unlike methods, attributes |
1246 | within the MOP are stored as meta-information only. They will be used |
1247 | later to construct instances from (see C<construct_instance> above). |
552e3d24 |
1248 | More details about the attribute meta-objects can be found in the |
a2e85e6c |
1249 | L<Class::MOP::Attribute> or the L<Class::MOP/The Attribute protocol> |
1250 | section. |
1251 | |
1252 | It should be noted that any accessor, reader/writer or predicate |
1253 | methods which the C<$attribute_meta_object> has will be installed |
1254 | into the class at this time. |
552e3d24 |
1255 | |
86482605 |
1256 | B<NOTE> |
1257 | If an attribute already exists for C<$attribute_name>, the old one |
1258 | will be removed (as well as removing all it's accessors), and then |
1259 | the new one added. |
1260 | |
552e3d24 |
1261 | =item B<has_attribute ($attribute_name)> |
1262 | |
a2e85e6c |
1263 | Checks to see if this class has an attribute by the name of |
552e3d24 |
1264 | C<$attribute_name> and returns a boolean. |
1265 | |
1266 | =item B<get_attribute ($attribute_name)> |
1267 | |
1268 | Returns the attribute meta-object associated with C<$attribute_name>, |
1269 | if none is found, it will return undef. |
1270 | |
1271 | =item B<remove_attribute ($attribute_name)> |
1272 | |
1273 | This will remove the attribute meta-object stored at |
1274 | C<$attribute_name>, then return the removed attribute meta-object. |
1275 | |
a2e85e6c |
1276 | B<NOTE:> |
1277 | Removing an attribute will only affect future instances of |
552e3d24 |
1278 | the class, it will not make any attempt to remove the attribute from |
1279 | any existing instances of the class. |
1280 | |
a2e85e6c |
1281 | It should be noted that any accessor, reader/writer or predicate |
1282 | methods which the attribute meta-object stored at C<$attribute_name> |
1283 | has will be removed from the class at this time. This B<will> make |
1284 | these attributes somewhat inaccessable in previously created |
1285 | instances. But if you are crazy enough to do this at runtime, then |
1286 | you are crazy enough to deal with something like this :). |
1287 | |
552e3d24 |
1288 | =item B<get_attribute_list> |
1289 | |
1290 | This returns a list of attribute names which are defined in the local |
1291 | class. If you want a list of all applicable attributes for a class, |
1292 | use the C<compute_all_applicable_attributes> method. |
1293 | |
1294 | =item B<compute_all_applicable_attributes> |
1295 | |
c9e77dbb |
1296 | This will traverse the inheritance heirachy and return a list of all |
1297 | the applicable attributes for this class. It does not construct a |
1298 | HASH reference like C<compute_all_applicable_methods> because all |
1299 | that same information is discoverable through the attribute |
1300 | meta-object itself. |
552e3d24 |
1301 | |
058c1cf5 |
1302 | =item B<find_attribute_by_name ($attr_name)> |
1303 | |
1304 | This method will traverse the inheritance heirachy and find the |
1305 | first attribute whose name matches C<$attr_name>, then return it. |
1306 | It will return undef if nothing is found. |
1307 | |
552e3d24 |
1308 | =back |
1309 | |
96e38ba6 |
1310 | =head2 Class Immutability |
857f87a7 |
1311 | |
1312 | =over 4 |
1313 | |
96e38ba6 |
1314 | =item B<make_immutable (%options)> |
1315 | |
1316 | This method will invoke a tranforamtion upon the class which will |
1317 | make it immutable. Details of this transformation can be found in |
1318 | the L<Class::MOP::Immutable> documentation. |
857f87a7 |
1319 | |
1320 | =back |
1321 | |
1a09d9cc |
1322 | =head1 AUTHORS |
8b978dd5 |
1323 | |
a2e85e6c |
1324 | Stevan Little E<lt>stevan@iinteractive.comE<gt> |
8b978dd5 |
1325 | |
1a09d9cc |
1326 | Yuval Kogman E<lt>nothingmuch@woobling.comE<gt> |
1327 | |
8b978dd5 |
1328 | =head1 COPYRIGHT AND LICENSE |
1329 | |
2367814a |
1330 | Copyright 2006, 2007 by Infinity Interactive, Inc. |
8b978dd5 |
1331 | |
1332 | L<http://www.iinteractive.com> |
1333 | |
1334 | This library is free software; you can redistribute it and/or modify |
1335 | it under the same terms as Perl itself. |
1336 | |
798baea5 |
1337 | =cut |