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'; |
10 | use B 'svref_2object'; |
a740253a |
11 | use Clone (); |
8b978dd5 |
12 | |
0dea7280 |
13 | our $VERSION = '0.05'; |
8b978dd5 |
14 | |
aa448b16 |
15 | # Self-introspection |
2eb717d5 |
16 | |
aa448b16 |
17 | sub meta { Class::MOP::Class->initialize(blessed($_[0]) || $_[0]) } |
2eb717d5 |
18 | |
8b978dd5 |
19 | # Creation |
20 | |
bfe4d0fc |
21 | { |
22 | # Metaclasses are singletons, so we cache them here. |
23 | # there is no need to worry about destruction though |
24 | # because they should die only when the program dies. |
25 | # After all, do package definitions even get reaped? |
651955fb |
26 | my %METAS; |
27 | |
bfe4d0fc |
28 | sub initialize { |
351bd7d4 |
29 | my $class = shift; |
30 | my $package_name = shift; |
22286063 |
31 | (defined $package_name && $package_name && !blessed($package_name)) |
32 | || confess "You must pass a package name and it cannot be blessed"; |
651955fb |
33 | $class->construct_class_instance(':package' => $package_name, @_); |
727919c5 |
34 | } |
35 | |
36 | # NOTE: (meta-circularity) |
37 | # this is a special form of &construct_instance |
38 | # (see below), which is used to construct class |
1a7ebbb3 |
39 | # meta-object instances for any Class::MOP::* |
40 | # class. All other classes will use the more |
41 | # normal &construct_instance. |
727919c5 |
42 | sub construct_class_instance { |
351bd7d4 |
43 | my $class = shift; |
651955fb |
44 | my %options = @_; |
45 | my $package_name = $options{':package'}; |
727919c5 |
46 | (defined $package_name && $package_name) |
651955fb |
47 | || confess "You must pass a package name"; |
48 | return $METAS{$package_name} if exists $METAS{$package_name}; |
1a7ebbb3 |
49 | $class = blessed($class) || $class; |
550d56db |
50 | # now create the metaclass |
51 | my $meta; |
1a7ebbb3 |
52 | if ($class =~ /^Class::MOP::/) { |
550d56db |
53 | $meta = bless { |
351bd7d4 |
54 | '$:package' => $package_name, |
55 | '%:attributes' => {}, |
550d56db |
56 | '$:attribute_metaclass' => $options{':attribute_metaclass'} || 'Class::MOP::Attribute', |
57 | '$:method_metaclass' => $options{':method_metaclass'} || 'Class::MOP::Method', |
1a7ebbb3 |
58 | } => $class; |
59 | } |
60 | else { |
5f3c057a |
61 | # NOTE: |
62 | # it is safe to use meta here because |
63 | # class will always be a subclass of |
64 | # Class::MOP::Class, which defines meta |
550d56db |
65 | $meta = bless $class->meta->construct_instance(%options) => $class |
1a7ebbb3 |
66 | } |
550d56db |
67 | # and check the metaclass compatibility |
68 | $meta->check_metaclass_compatability(); |
69 | $METAS{$package_name} = $meta; |
70 | } |
71 | |
72 | sub check_metaclass_compatability { |
73 | my $self = shift; |
74 | |
75 | # this is always okay ... |
76 | return if blessed($self) eq 'Class::MOP::Class'; |
77 | |
78 | my @class_list = $self->class_precedence_list; |
79 | shift @class_list; # shift off $self->name |
80 | |
81 | foreach my $class_name (@class_list) { |
550d56db |
82 | my $meta = $METAS{$class_name}; |
83 | ($self->isa(blessed($meta))) |
84 | || confess $self->name . "->meta => (" . (blessed($self)) . ")" . |
85 | " is not compatible with the " . |
86 | $class_name . "->meta => (" . (blessed($meta)) . ")"; |
87 | } |
bfe4d0fc |
88 | } |
8b978dd5 |
89 | } |
90 | |
91 | sub create { |
92 | my ($class, $package_name, $package_version, %options) = @_; |
bfe4d0fc |
93 | (defined $package_name && $package_name) |
8b978dd5 |
94 | || confess "You must pass a package name"; |
95 | my $code = "package $package_name;"; |
96 | $code .= "\$$package_name\:\:VERSION = '$package_version';" |
97 | if defined $package_version; |
98 | eval $code; |
99 | confess "creation of $package_name failed : $@" if $@; |
bfe4d0fc |
100 | my $meta = $class->initialize($package_name); |
aa448b16 |
101 | |
102 | $meta->add_method('meta' => sub { |
103 | Class::MOP::Class->initialize(blessed($_[0]) || $_[0]); |
104 | }); |
105 | |
8b978dd5 |
106 | $meta->superclasses(@{$options{superclasses}}) |
107 | if exists $options{superclasses}; |
2eb717d5 |
108 | # NOTE: |
109 | # process attributes first, so that they can |
110 | # install accessors, but locally defined methods |
111 | # can then overwrite them. It is maybe a little odd, but |
112 | # I think this should be the order of things. |
113 | if (exists $options{attributes}) { |
cbd9f942 |
114 | foreach my $attr (@{$options{attributes}}) { |
115 | $meta->add_attribute($attr); |
2eb717d5 |
116 | } |
117 | } |
bfe4d0fc |
118 | if (exists $options{methods}) { |
119 | foreach my $method_name (keys %{$options{methods}}) { |
120 | $meta->add_method($method_name, $options{methods}->{$method_name}); |
121 | } |
2eb717d5 |
122 | } |
8b978dd5 |
123 | return $meta; |
124 | } |
125 | |
7b31baf4 |
126 | ## Attribute readers |
127 | |
128 | # NOTE: |
129 | # all these attribute readers will be bootstrapped |
130 | # away in the Class::MOP bootstrap section |
131 | |
132 | sub name { $_[0]->{'$:package'} } |
133 | sub get_attribute_map { $_[0]->{'%:attributes'} } |
134 | sub attribute_metaclass { $_[0]->{'$:attribute_metaclass'} } |
135 | sub method_metaclass { $_[0]->{'$:method_metaclass'} } |
136 | |
c9e77dbb |
137 | # Instance Construction & Cloning |
138 | |
5f3c057a |
139 | sub new_object { |
140 | my $class = shift; |
651955fb |
141 | # NOTE: |
142 | # we need to protect the integrity of the |
143 | # Class::MOP::Class singletons here, so we |
144 | # delegate this to &construct_class_instance |
145 | # which will deal with the singletons |
146 | return $class->construct_class_instance(@_) |
147 | if $class->name->isa('Class::MOP::Class'); |
5f3c057a |
148 | bless $class->construct_instance(@_) => $class->name; |
149 | } |
e16da3e6 |
150 | |
151 | sub construct_instance { |
cbd9f942 |
152 | my ($class, %params) = @_; |
153 | my $instance = {}; |
c9e77dbb |
154 | foreach my $attr ($class->compute_all_applicable_attributes()) { |
651955fb |
155 | my $init_arg = $attr->init_arg(); |
cbd9f942 |
156 | # try to fetch the init arg from the %params ... |
157 | my $val; |
158 | $val = $params{$init_arg} if exists $params{$init_arg}; |
159 | # if nothing was in the %params, we can use the |
160 | # attribute's default value (if it has one) |
c9e77dbb |
161 | $val ||= $attr->default($instance) if $attr->has_default(); |
cbd9f942 |
162 | $instance->{$attr->name} = $val; |
163 | } |
164 | return $instance; |
e16da3e6 |
165 | } |
166 | |
5f3c057a |
167 | sub clone_object { |
168 | my $class = shift; |
7b31baf4 |
169 | my $instance = shift; |
651955fb |
170 | (blessed($instance) && $instance->isa($class->name)) |
171 | || confess "You must pass an instance ($instance) of the metaclass (" . $class->name . ")"; |
172 | # NOTE: |
173 | # we need to protect the integrity of the |
174 | # Class::MOP::Class singletons here, they |
a740253a |
175 | # should not be cloned. |
651955fb |
176 | return $instance if $instance->isa('Class::MOP::Class'); |
177 | bless $class->clone_instance($instance, @_) => blessed($instance); |
5f3c057a |
178 | } |
179 | |
c9e77dbb |
180 | sub clone_instance { |
651955fb |
181 | my ($class, $instance, %params) = @_; |
182 | (blessed($instance)) |
c9e77dbb |
183 | || confess "You can only clone instances, \$self is not a blessed instance"; |
19d4b5b8 |
184 | my $clone = { %$instance, %params }; |
c9e77dbb |
185 | return $clone; |
186 | } |
187 | |
8b978dd5 |
188 | # Informational |
189 | |
7b31baf4 |
190 | # &name should be here too, but it is above |
191 | # because it gets bootstrapped away |
8b978dd5 |
192 | |
193 | sub version { |
194 | my $self = shift; |
195 | no strict 'refs'; |
196 | ${$self->name . '::VERSION'}; |
197 | } |
198 | |
199 | # Inheritance |
200 | |
201 | sub superclasses { |
202 | my $self = shift; |
203 | no strict 'refs'; |
204 | if (@_) { |
205 | my @supers = @_; |
206 | @{$self->name . '::ISA'} = @supers; |
207 | } |
208 | @{$self->name . '::ISA'}; |
209 | } |
210 | |
211 | sub class_precedence_list { |
212 | my $self = shift; |
bfe4d0fc |
213 | # NOTE: |
214 | # We need to check for ciruclar inheirtance here. |
215 | # This will do nothing if all is well, and blow |
216 | # up otherwise. Yes, it's an ugly hack, better |
217 | # suggestions are welcome. |
218 | { $self->name->isa('This is a test for circular inheritance') } |
219 | # ... and no back to our regularly scheduled program |
8b978dd5 |
220 | ( |
221 | $self->name, |
222 | map { |
bfe4d0fc |
223 | $self->initialize($_)->class_precedence_list() |
8b978dd5 |
224 | } $self->superclasses() |
225 | ); |
226 | } |
227 | |
0882828e |
228 | ## Methods |
229 | |
230 | sub add_method { |
231 | my ($self, $method_name, $method) = @_; |
232 | (defined $method_name && $method_name) |
233 | || confess "You must define a method name"; |
a5eca695 |
234 | # use reftype here to allow for blessed subs ... |
0882828e |
235 | (reftype($method) && reftype($method) eq 'CODE') |
236 | || confess "Your code block must be a CODE reference"; |
237 | my $full_method_name = ($self->name . '::' . $method_name); |
238 | |
239 | no strict 'refs'; |
c9b8b7f9 |
240 | no warnings 'redefine'; |
22286063 |
241 | *{$full_method_name} = subname $full_method_name => $method; |
0882828e |
242 | } |
243 | |
663f8198 |
244 | sub alias_method { |
245 | my ($self, $method_name, $method) = @_; |
246 | (defined $method_name && $method_name) |
247 | || confess "You must define a method name"; |
248 | # use reftype here to allow for blessed subs ... |
249 | (reftype($method) && reftype($method) eq 'CODE') |
250 | || confess "Your code block must be a CODE reference"; |
251 | my $full_method_name = ($self->name . '::' . $method_name); |
252 | |
253 | no strict 'refs'; |
254 | no warnings 'redefine'; |
255 | *{$full_method_name} = $method; |
256 | } |
257 | |
bfe4d0fc |
258 | { |
259 | |
260 | ## private utility functions for has_method |
2eb717d5 |
261 | my $_find_subroutine_package_name = sub { eval { svref_2object($_[0])->GV->STASH->NAME } || '' }; |
262 | my $_find_subroutine_name = sub { eval { svref_2object($_[0])->GV->NAME } || '' }; |
bfe4d0fc |
263 | |
264 | sub has_method { |
c9b8b7f9 |
265 | my ($self, $method_name) = @_; |
bfe4d0fc |
266 | (defined $method_name && $method_name) |
267 | || confess "You must define a method name"; |
0882828e |
268 | |
bfe4d0fc |
269 | my $sub_name = ($self->name . '::' . $method_name); |
0882828e |
270 | |
bfe4d0fc |
271 | no strict 'refs'; |
272 | return 0 if !defined(&{$sub_name}); |
273 | return 0 if $_find_subroutine_package_name->(\&{$sub_name}) ne $self->name && |
274 | $_find_subroutine_name->(\&{$sub_name}) ne '__ANON__'; |
275 | return 1; |
276 | } |
277 | |
0882828e |
278 | } |
279 | |
280 | sub get_method { |
c9b8b7f9 |
281 | my ($self, $method_name) = @_; |
0882828e |
282 | (defined $method_name && $method_name) |
283 | || confess "You must define a method name"; |
284 | |
285 | no strict 'refs'; |
286 | return \&{$self->name . '::' . $method_name} |
bfe4d0fc |
287 | if $self->has_method($method_name); |
c9b8b7f9 |
288 | return; # <- make sure to return undef |
289 | } |
290 | |
291 | sub remove_method { |
292 | my ($self, $method_name) = @_; |
293 | (defined $method_name && $method_name) |
294 | || confess "You must define a method name"; |
295 | |
296 | my $removed_method = $self->get_method($method_name); |
297 | |
298 | no strict 'refs'; |
299 | delete ${$self->name . '::'}{$method_name} |
300 | if defined $removed_method; |
301 | |
302 | return $removed_method; |
303 | } |
304 | |
305 | sub get_method_list { |
306 | my $self = shift; |
307 | no strict 'refs'; |
a5eca695 |
308 | grep { $self->has_method($_) } %{$self->name . '::'}; |
309 | } |
310 | |
311 | sub compute_all_applicable_methods { |
312 | my $self = shift; |
313 | my @methods; |
314 | # keep a record of what we have seen |
315 | # here, this will handle all the |
316 | # inheritence issues because we are |
317 | # using the &class_precedence_list |
318 | my (%seen_class, %seen_method); |
319 | foreach my $class ($self->class_precedence_list()) { |
320 | next if $seen_class{$class}; |
321 | $seen_class{$class}++; |
322 | # fetch the meta-class ... |
323 | my $meta = $self->initialize($class); |
324 | foreach my $method_name ($meta->get_method_list()) { |
325 | next if exists $seen_method{$method_name}; |
326 | $seen_method{$method_name}++; |
327 | push @methods => { |
328 | name => $method_name, |
329 | class => $class, |
330 | code => $meta->get_method($method_name) |
331 | }; |
332 | } |
333 | } |
334 | return @methods; |
335 | } |
336 | |
a5eca695 |
337 | sub find_all_methods_by_name { |
338 | my ($self, $method_name) = @_; |
339 | (defined $method_name && $method_name) |
340 | || confess "You must define a method name to find"; |
341 | my @methods; |
342 | # keep a record of what we have seen |
343 | # here, this will handle all the |
344 | # inheritence issues because we are |
345 | # using the &class_precedence_list |
346 | my %seen_class; |
347 | foreach my $class ($self->class_precedence_list()) { |
348 | next if $seen_class{$class}; |
349 | $seen_class{$class}++; |
350 | # fetch the meta-class ... |
aa448b16 |
351 | my $meta = $self->initialize($class);; |
a5eca695 |
352 | push @methods => { |
353 | name => $method_name, |
354 | class => $class, |
355 | code => $meta->get_method($method_name) |
356 | } if $meta->has_method($method_name); |
357 | } |
358 | return @methods; |
359 | |
8b978dd5 |
360 | } |
361 | |
552e3d24 |
362 | ## Attributes |
363 | |
e16da3e6 |
364 | sub add_attribute { |
2e41896e |
365 | my $self = shift; |
366 | # either we have an attribute object already |
367 | # or we need to create one from the args provided |
368 | my $attribute = blessed($_[0]) ? $_[0] : $self->attribute_metaclass->new(@_); |
369 | # make sure it is derived from the correct type though |
370 | ($attribute->isa('Class::MOP::Attribute')) |
371 | || confess "Your attribute must be an instance of Class::MOP::Attribute (or a subclass)"; |
9ec169fe |
372 | $attribute->attach_to_class($self); |
373 | $attribute->install_accessors(); |
7b31baf4 |
374 | $self->get_attribute_map->{$attribute->name} = $attribute; |
e16da3e6 |
375 | } |
376 | |
377 | sub has_attribute { |
378 | my ($self, $attribute_name) = @_; |
379 | (defined $attribute_name && $attribute_name) |
380 | || confess "You must define an attribute name"; |
7b31baf4 |
381 | exists $self->get_attribute_map->{$attribute_name} ? 1 : 0; |
e16da3e6 |
382 | } |
383 | |
384 | sub get_attribute { |
385 | my ($self, $attribute_name) = @_; |
386 | (defined $attribute_name && $attribute_name) |
387 | || confess "You must define an attribute name"; |
7b31baf4 |
388 | return $self->get_attribute_map->{$attribute_name} |
22286063 |
389 | if $self->has_attribute($attribute_name); |
390 | return; |
e16da3e6 |
391 | } |
392 | |
393 | sub remove_attribute { |
394 | my ($self, $attribute_name) = @_; |
395 | (defined $attribute_name && $attribute_name) |
396 | || confess "You must define an attribute name"; |
7b31baf4 |
397 | my $removed_attribute = $self->get_attribute_map->{$attribute_name}; |
22286063 |
398 | return unless defined $removed_attribute; |
399 | delete $self->get_attribute_map->{$attribute_name}; |
9ec169fe |
400 | $removed_attribute->remove_accessors(); |
401 | $removed_attribute->detach_from_class(); |
e16da3e6 |
402 | return $removed_attribute; |
403 | } |
404 | |
405 | sub get_attribute_list { |
406 | my $self = shift; |
7b31baf4 |
407 | keys %{$self->get_attribute_map}; |
e16da3e6 |
408 | } |
409 | |
410 | sub compute_all_applicable_attributes { |
411 | my $self = shift; |
412 | my @attrs; |
413 | # keep a record of what we have seen |
414 | # here, this will handle all the |
415 | # inheritence issues because we are |
416 | # using the &class_precedence_list |
417 | my (%seen_class, %seen_attr); |
418 | foreach my $class ($self->class_precedence_list()) { |
419 | next if $seen_class{$class}; |
420 | $seen_class{$class}++; |
421 | # fetch the meta-class ... |
422 | my $meta = $self->initialize($class); |
423 | foreach my $attr_name ($meta->get_attribute_list()) { |
424 | next if exists $seen_attr{$attr_name}; |
425 | $seen_attr{$attr_name}++; |
c9e77dbb |
426 | push @attrs => $meta->get_attribute($attr_name); |
e16da3e6 |
427 | } |
428 | } |
429 | return @attrs; |
430 | } |
2eb717d5 |
431 | |
52e8a34c |
432 | # Class attributes |
433 | |
434 | sub add_package_variable { |
435 | my ($self, $variable, $initial_value) = @_; |
436 | (defined $variable && $variable =~ /^[\$\@\%]/) |
437 | || confess "variable name does not have a sigil"; |
438 | |
439 | my ($sigil, $name) = ($variable =~ /^(.)(.*)$/); |
440 | if (defined $initial_value) { |
441 | no strict 'refs'; |
442 | *{$self->name . '::' . $name} = $initial_value; |
443 | } |
444 | else { |
445 | eval $sigil . $self->name . '::' . $name; |
446 | confess "Could not create package variable ($variable) because : $@" if $@; |
447 | } |
448 | } |
449 | |
450 | sub has_package_variable { |
451 | my ($self, $variable) = @_; |
452 | (defined $variable && $variable =~ /^[\$\@\%]/) |
453 | || confess "variable name does not have a sigil"; |
454 | my ($sigil, $name) = ($variable =~ /^(.)(.*)$/); |
455 | no strict 'refs'; |
456 | defined ${$self->name . '::'}{$name} ? 1 : 0; |
457 | } |
458 | |
459 | sub get_package_variable { |
460 | my ($self, $variable) = @_; |
461 | (defined $variable && $variable =~ /^[\$\@\%]/) |
462 | || confess "variable name does not have a sigil"; |
463 | my ($sigil, $name) = ($variable =~ /^(.)(.*)$/); |
464 | no strict 'refs'; |
465 | # try to fetch it first,.. see what happens |
18697ac8 |
466 | my $ref = eval '\\' . $sigil . $self->name . '::' . $name; |
52e8a34c |
467 | confess "Could not get the package variable ($variable) because : $@" if $@; |
468 | # if we didn't die, then we can return it |
18697ac8 |
469 | return $ref; |
52e8a34c |
470 | } |
471 | |
472 | sub remove_package_variable { |
473 | my ($self, $variable) = @_; |
474 | (defined $variable && $variable =~ /^[\$\@\%]/) |
475 | || confess "variable name does not have a sigil"; |
476 | my ($sigil, $name) = ($variable =~ /^(.)(.*)$/); |
477 | no strict 'refs'; |
478 | delete ${$self->name . '::'}{$name}; |
479 | } |
480 | |
8b978dd5 |
481 | 1; |
482 | |
483 | __END__ |
484 | |
485 | =pod |
486 | |
487 | =head1 NAME |
488 | |
489 | Class::MOP::Class - Class Meta Object |
490 | |
491 | =head1 SYNOPSIS |
492 | |
fe122940 |
493 | # use this for introspection ... |
494 | |
fe122940 |
495 | # add a method to Foo ... |
496 | Foo->meta->add_method('bar' => sub { ... }) |
497 | |
498 | # get a list of all the classes searched |
499 | # the method dispatcher in the correct order |
500 | Foo->meta->class_precedence_list() |
501 | |
502 | # remove a method from Foo |
503 | Foo->meta->remove_method('bar'); |
504 | |
505 | # or use this to actually create classes ... |
506 | |
507 | Class::MOP::Class->create('Bar' => '0.01' => ( |
508 | superclasses => [ 'Foo' ], |
509 | attributes => [ |
510 | Class::MOP:::Attribute->new('$bar'), |
511 | Class::MOP:::Attribute->new('$baz'), |
512 | ], |
513 | methods => { |
514 | calculate_bar => sub { ... }, |
515 | construct_baz => sub { ... } |
516 | } |
517 | )); |
518 | |
8b978dd5 |
519 | =head1 DESCRIPTION |
520 | |
fe122940 |
521 | This is the largest and currently most complex part of the Perl 5 |
522 | meta-object protocol. It controls the introspection and |
523 | manipulation of Perl 5 classes (and it can create them too). The |
524 | best way to understand what this module can do, is to read the |
525 | documentation for each of it's methods. |
526 | |
552e3d24 |
527 | =head1 METHODS |
528 | |
2eb717d5 |
529 | =head2 Self Introspection |
530 | |
531 | =over 4 |
532 | |
533 | =item B<meta> |
534 | |
fe122940 |
535 | This will return a B<Class::MOP::Class> instance which is related |
536 | to this class. Thereby allowing B<Class::MOP::Class> to actually |
537 | introspect itself. |
538 | |
539 | As with B<Class::MOP::Attribute>, B<Class::MOP> will actually |
540 | bootstrap this module by installing a number of attribute meta-objects |
541 | into it's metaclass. This will allow this class to reap all the benifits |
542 | of the MOP when subclassing it. |
2eb717d5 |
543 | |
544 | =back |
545 | |
552e3d24 |
546 | =head2 Class construction |
547 | |
a2e85e6c |
548 | These methods will handle creating B<Class::MOP::Class> objects, |
549 | which can be used to both create new classes, and analyze |
550 | pre-existing classes. |
552e3d24 |
551 | |
552 | This module will internally store references to all the instances |
553 | you create with these methods, so that they do not need to be |
554 | created any more than nessecary. Basically, they are singletons. |
555 | |
556 | =over 4 |
557 | |
558 | =item B<create ($package_name, ?$package_version, |
a2e85e6c |
559 | superclasses =E<gt> ?@superclasses, |
560 | methods =E<gt> ?%methods, |
561 | attributes =E<gt> ?%attributes)> |
552e3d24 |
562 | |
a2e85e6c |
563 | This returns a B<Class::MOP::Class> object, bringing the specified |
552e3d24 |
564 | C<$package_name> into existence and adding any of the |
565 | C<$package_version>, C<@superclasses>, C<%methods> and C<%attributes> |
566 | to it. |
567 | |
568 | =item B<initialize ($package_name)> |
569 | |
a2e85e6c |
570 | This initializes and returns returns a B<Class::MOP::Class> object |
571 | for a given a C<$package_name>. |
572 | |
651955fb |
573 | =item B<construct_class_instance (%options)> |
a2e85e6c |
574 | |
575 | This will construct an instance of B<Class::MOP::Class>, it is |
576 | here so that we can actually "tie the knot" for B<Class::MOP::Class> |
577 | to use C<construct_instance> once all the bootstrapping is done. This |
578 | method is used internally by C<initialize> and should never be called |
579 | from outside of that method really. |
552e3d24 |
580 | |
550d56db |
581 | =item B<check_metaclass_compatability> |
582 | |
583 | This method is called as the very last thing in the |
584 | C<construct_class_instance> method. This will check that the |
585 | metaclass you are creating is compatible with the metaclasses of all |
586 | your ancestors. For more inforamtion about metaclass compatibility |
587 | see the C<About Metaclass compatibility> section in L<Class::MOP>. |
588 | |
552e3d24 |
589 | =back |
590 | |
c9e77dbb |
591 | =head2 Object instance construction and cloning |
a2e85e6c |
592 | |
c9e77dbb |
593 | These methods are B<entirely optional>, it is up to you whether you want |
594 | to use them or not. |
552e3d24 |
595 | |
596 | =over 4 |
597 | |
5f3c057a |
598 | =item B<new_object (%params)> |
599 | |
600 | This is a convience method for creating a new object of the class, and |
601 | blessing it into the appropriate package as well. Ideally your class |
602 | would call a C<new> this method like so: |
603 | |
604 | sub MyClass::new { |
605 | my ($class, %param) = @_; |
606 | $class->meta->new_object(%params); |
607 | } |
608 | |
609 | Of course the ideal place for this would actually be in C<UNIVERSAL::> |
610 | but that is considered bad style, so we do not do that. |
611 | |
cbd9f942 |
612 | =item B<construct_instance (%params)> |
552e3d24 |
613 | |
c9e77dbb |
614 | This method is used to construct an instace structure suitable for |
615 | C<bless>-ing into your package of choice. It works in conjunction |
616 | with the Attribute protocol to collect all applicable attributes. |
617 | |
cbd9f942 |
618 | This will construct and instance using a HASH ref as storage |
552e3d24 |
619 | (currently only HASH references are supported). This will collect all |
a2e85e6c |
620 | the applicable attributes and layout out the fields in the HASH ref, |
621 | it will then initialize them using either use the corresponding key |
622 | in C<%params> or any default value or initializer found in the |
623 | attribute meta-object. |
727919c5 |
624 | |
5f3c057a |
625 | =item B<clone_object ($instance, %params)> |
626 | |
627 | This is a convience method for cloning an object instance, then |
19d4b5b8 |
628 | blessing it into the appropriate package. This method will call |
629 | C<clone_instance>, which performs a shallow copy of the object, |
630 | see that methods documentation for more details. Ideally your |
631 | class would call a C<clone> this method like so: |
5f3c057a |
632 | |
633 | sub MyClass::clone { |
634 | my ($self, %param) = @_; |
635 | $self->meta->clone_object($self, %params); |
636 | } |
637 | |
638 | Of course the ideal place for this would actually be in C<UNIVERSAL::> |
639 | but that is considered bad style, so we do not do that. |
640 | |
c9e77dbb |
641 | =item B<clone_instance($instance, %params)> |
642 | |
643 | This method is a compliment of C<construct_instance> (which means if |
19d4b5b8 |
644 | you override C<construct_instance>, you need to override this one too), |
645 | and clones the instance shallowly. |
a27ae83f |
646 | |
647 | The cloned structure returned is (like with C<construct_instance>) an |
648 | unC<bless>ed HASH reference, it is your responsibility to then bless |
649 | this cloned structure into the right class (which C<clone_object> will |
650 | do for you). |
c9e77dbb |
651 | |
19d4b5b8 |
652 | As of 0.11, this method will clone the C<$instance> structure shallowly, |
653 | as opposed to the deep cloning implemented in prior versions. After much |
654 | thought, research and discussion, I have decided that anything but basic |
655 | shallow cloning is outside the scope of the meta-object protocol. I |
656 | think Yuval "nothingmuch" Kogman put it best when he said that cloning |
657 | is too I<context-specific> to be part of the MOP. |
658 | |
552e3d24 |
659 | =back |
660 | |
661 | =head2 Informational |
662 | |
663 | =over 4 |
664 | |
665 | =item B<name> |
666 | |
a2e85e6c |
667 | This is a read-only attribute which returns the package name for the |
668 | given B<Class::MOP::Class> instance. |
552e3d24 |
669 | |
670 | =item B<version> |
671 | |
672 | This is a read-only attribute which returns the C<$VERSION> of the |
a2e85e6c |
673 | package for the given B<Class::MOP::Class> instance. |
552e3d24 |
674 | |
675 | =back |
676 | |
677 | =head2 Inheritance Relationships |
678 | |
679 | =over 4 |
680 | |
681 | =item B<superclasses (?@superclasses)> |
682 | |
683 | This is a read-write attribute which represents the superclass |
a2e85e6c |
684 | relationships of the class the B<Class::MOP::Class> instance is |
685 | associated with. Basically, it can get and set the C<@ISA> for you. |
552e3d24 |
686 | |
343203ee |
687 | B<NOTE:> |
688 | Perl will occasionally perform some C<@ISA> and method caching, if |
689 | you decide to change your superclass relationship at runtime (which |
690 | is quite insane and very much not recommened), then you should be |
691 | aware of this and the fact that this module does not make any |
692 | attempt to address this issue. |
693 | |
552e3d24 |
694 | =item B<class_precedence_list> |
695 | |
a2e85e6c |
696 | This computes the a list of all the class's ancestors in the same order |
697 | in which method dispatch will be done. This is similair to |
698 | what B<Class::ISA::super_path> does, but we don't remove duplicate names. |
552e3d24 |
699 | |
700 | =back |
701 | |
702 | =head2 Methods |
703 | |
704 | =over 4 |
705 | |
2e41896e |
706 | =item B<method_metaclass> |
707 | |
552e3d24 |
708 | =item B<add_method ($method_name, $method)> |
709 | |
710 | This will take a C<$method_name> and CODE reference to that |
a2e85e6c |
711 | C<$method> and install it into the class's package. |
552e3d24 |
712 | |
a2e85e6c |
713 | B<NOTE>: |
714 | This does absolutely nothing special to C<$method> |
552e3d24 |
715 | other than use B<Sub::Name> to make sure it is tagged with the |
716 | correct name, and therefore show up correctly in stack traces and |
717 | such. |
718 | |
663f8198 |
719 | =item B<alias_method ($method_name, $method)> |
720 | |
721 | This will take a C<$method_name> and CODE reference to that |
722 | C<$method> and alias the method into the class's package. |
723 | |
724 | B<NOTE>: |
725 | Unlike C<add_method>, this will B<not> try to name the |
726 | C<$method> using B<Sub::Name>, it only aliases the method in |
727 | the class's package. |
728 | |
552e3d24 |
729 | =item B<has_method ($method_name)> |
730 | |
a2e85e6c |
731 | This just provides a simple way to check if the class implements |
552e3d24 |
732 | a specific C<$method_name>. It will I<not> however, attempt to check |
a2e85e6c |
733 | if the class inherits the method (use C<UNIVERSAL::can> for that). |
552e3d24 |
734 | |
735 | This will correctly handle functions defined outside of the package |
736 | that use a fully qualified name (C<sub Package::name { ... }>). |
737 | |
738 | This will correctly handle functions renamed with B<Sub::Name> and |
739 | installed using the symbol tables. However, if you are naming the |
740 | subroutine outside of the package scope, you must use the fully |
741 | qualified name, including the package name, for C<has_method> to |
742 | correctly identify it. |
743 | |
744 | This will attempt to correctly ignore functions imported from other |
745 | packages using B<Exporter>. It breaks down if the function imported |
746 | is an C<__ANON__> sub (such as with C<use constant>), which very well |
747 | may be a valid method being applied to the class. |
748 | |
749 | In short, this method cannot always be trusted to determine if the |
750 | C<$method_name> is actually a method. However, it will DWIM about |
a2e85e6c |
751 | 90% of the time, so it's a small trade off I think. |
552e3d24 |
752 | |
753 | =item B<get_method ($method_name)> |
754 | |
755 | This will return a CODE reference of the specified C<$method_name>, |
756 | or return undef if that method does not exist. |
757 | |
758 | =item B<remove_method ($method_name)> |
759 | |
a2e85e6c |
760 | This will attempt to remove a given C<$method_name> from the class. |
552e3d24 |
761 | It will return the CODE reference that it has removed, and will |
762 | attempt to use B<Sub::Name> to clear the methods associated name. |
763 | |
764 | =item B<get_method_list> |
765 | |
766 | This will return a list of method names for all I<locally> defined |
767 | methods. It does B<not> provide a list of all applicable methods, |
768 | including any inherited ones. If you want a list of all applicable |
769 | methods, use the C<compute_all_applicable_methods> method. |
770 | |
771 | =item B<compute_all_applicable_methods> |
772 | |
a2e85e6c |
773 | This will return a list of all the methods names this class will |
774 | respond to, taking into account inheritance. The list will be a list of |
552e3d24 |
775 | HASH references, each one containing the following information; method |
776 | name, the name of the class in which the method lives and a CODE |
777 | reference for the actual method. |
778 | |
779 | =item B<find_all_methods_by_name ($method_name)> |
780 | |
781 | This will traverse the inheritence hierarchy and locate all methods |
782 | with a given C<$method_name>. Similar to |
783 | C<compute_all_applicable_methods> it returns a list of HASH references |
784 | with the following information; method name (which will always be the |
785 | same as C<$method_name>), the name of the class in which the method |
786 | lives and a CODE reference for the actual method. |
787 | |
788 | The list of methods produced is a distinct list, meaning there are no |
789 | duplicates in it. This is especially useful for things like object |
790 | initialization and destruction where you only want the method called |
791 | once, and in the correct order. |
792 | |
793 | =back |
794 | |
795 | =head2 Attributes |
796 | |
797 | It should be noted that since there is no one consistent way to define |
798 | the attributes of a class in Perl 5. These methods can only work with |
799 | the information given, and can not easily discover information on |
a2e85e6c |
800 | their own. See L<Class::MOP::Attribute> for more details. |
552e3d24 |
801 | |
802 | =over 4 |
803 | |
2e41896e |
804 | =item B<attribute_metaclass> |
805 | |
7b31baf4 |
806 | =item B<get_attribute_map> |
807 | |
552e3d24 |
808 | =item B<add_attribute ($attribute_name, $attribute_meta_object)> |
809 | |
a2e85e6c |
810 | This stores a C<$attribute_meta_object> in the B<Class::MOP::Class> |
811 | instance associated with the given class, and associates it with |
812 | the C<$attribute_name>. Unlike methods, attributes within the MOP |
813 | are stored as meta-information only. They will be used later to |
814 | construct instances from (see C<construct_instance> above). |
552e3d24 |
815 | More details about the attribute meta-objects can be found in the |
a2e85e6c |
816 | L<Class::MOP::Attribute> or the L<Class::MOP/The Attribute protocol> |
817 | section. |
818 | |
819 | It should be noted that any accessor, reader/writer or predicate |
820 | methods which the C<$attribute_meta_object> has will be installed |
821 | into the class at this time. |
552e3d24 |
822 | |
823 | =item B<has_attribute ($attribute_name)> |
824 | |
a2e85e6c |
825 | Checks to see if this class has an attribute by the name of |
552e3d24 |
826 | C<$attribute_name> and returns a boolean. |
827 | |
828 | =item B<get_attribute ($attribute_name)> |
829 | |
830 | Returns the attribute meta-object associated with C<$attribute_name>, |
831 | if none is found, it will return undef. |
832 | |
833 | =item B<remove_attribute ($attribute_name)> |
834 | |
835 | This will remove the attribute meta-object stored at |
836 | C<$attribute_name>, then return the removed attribute meta-object. |
837 | |
a2e85e6c |
838 | B<NOTE:> |
839 | Removing an attribute will only affect future instances of |
552e3d24 |
840 | the class, it will not make any attempt to remove the attribute from |
841 | any existing instances of the class. |
842 | |
a2e85e6c |
843 | It should be noted that any accessor, reader/writer or predicate |
844 | methods which the attribute meta-object stored at C<$attribute_name> |
845 | has will be removed from the class at this time. This B<will> make |
846 | these attributes somewhat inaccessable in previously created |
847 | instances. But if you are crazy enough to do this at runtime, then |
848 | you are crazy enough to deal with something like this :). |
849 | |
552e3d24 |
850 | =item B<get_attribute_list> |
851 | |
852 | This returns a list of attribute names which are defined in the local |
853 | class. If you want a list of all applicable attributes for a class, |
854 | use the C<compute_all_applicable_attributes> method. |
855 | |
856 | =item B<compute_all_applicable_attributes> |
857 | |
c9e77dbb |
858 | This will traverse the inheritance heirachy and return a list of all |
859 | the applicable attributes for this class. It does not construct a |
860 | HASH reference like C<compute_all_applicable_methods> because all |
861 | that same information is discoverable through the attribute |
862 | meta-object itself. |
552e3d24 |
863 | |
864 | =back |
865 | |
52e8a34c |
866 | =head2 Package Variables |
867 | |
868 | Since Perl's classes are built atop the Perl package system, it is |
869 | fairly common to use package scoped variables for things like static |
870 | class variables. The following methods are convience methods for |
871 | the creation and inspection of package scoped variables. |
872 | |
873 | =over 4 |
874 | |
875 | =item B<add_package_variable ($variable_name, ?$initial_value)> |
876 | |
877 | Given a C<$variable_name>, which must contain a leading sigil, this |
878 | method will create that variable within the package which houses the |
879 | class. It also takes an optional C<$initial_value>, which must be a |
880 | reference of the same type as the sigil of the C<$variable_name> |
881 | implies. |
882 | |
883 | =item B<get_package_variable ($variable_name)> |
884 | |
885 | This will return a reference to the package variable in |
886 | C<$variable_name>. |
887 | |
888 | =item B<has_package_variable ($variable_name)> |
889 | |
890 | Returns true (C<1>) if there is a package variable defined for |
891 | C<$variable_name>, and false (C<0>) otherwise. |
892 | |
893 | =item B<remove_package_variable ($variable_name)> |
894 | |
895 | This will attempt to remove the package variable at C<$variable_name>. |
896 | |
897 | =back |
898 | |
8b978dd5 |
899 | =head1 AUTHOR |
900 | |
a2e85e6c |
901 | Stevan Little E<lt>stevan@iinteractive.comE<gt> |
8b978dd5 |
902 | |
903 | =head1 COPYRIGHT AND LICENSE |
904 | |
905 | Copyright 2006 by Infinity Interactive, Inc. |
906 | |
907 | L<http://www.iinteractive.com> |
908 | |
909 | This library is free software; you can redistribute it and/or modify |
910 | it under the same terms as Perl itself. |
911 | |
912 | =cut |