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 | |
99e5b7e8 |
13 | our $VERSION = '0.03'; |
8b978dd5 |
14 | |
2eb717d5 |
15 | # Self-introspection |
16 | |
99e5b7e8 |
17 | sub meta { Class::MOP::Class->initialize($_[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; |
bfe4d0fc |
31 | (defined $package_name && $package_name) |
c9e77dbb |
32 | || confess "You must pass a package name"; |
33 | # make sure the package name is not blessed |
34 | $package_name = blessed($package_name) || $package_name; |
651955fb |
35 | $class->construct_class_instance(':package' => $package_name, @_); |
727919c5 |
36 | } |
37 | |
38 | # NOTE: (meta-circularity) |
39 | # this is a special form of &construct_instance |
40 | # (see below), which is used to construct class |
1a7ebbb3 |
41 | # meta-object instances for any Class::MOP::* |
42 | # class. All other classes will use the more |
43 | # normal &construct_instance. |
727919c5 |
44 | sub construct_class_instance { |
351bd7d4 |
45 | my $class = shift; |
651955fb |
46 | my %options = @_; |
47 | my $package_name = $options{':package'}; |
727919c5 |
48 | (defined $package_name && $package_name) |
651955fb |
49 | || confess "You must pass a package name"; |
50 | return $METAS{$package_name} if exists $METAS{$package_name}; |
1a7ebbb3 |
51 | $class = blessed($class) || $class; |
550d56db |
52 | # now create the metaclass |
53 | my $meta; |
1a7ebbb3 |
54 | if ($class =~ /^Class::MOP::/) { |
550d56db |
55 | $meta = bless { |
351bd7d4 |
56 | '$:package' => $package_name, |
57 | '%:attributes' => {}, |
550d56db |
58 | '$:attribute_metaclass' => $options{':attribute_metaclass'} || 'Class::MOP::Attribute', |
59 | '$:method_metaclass' => $options{':method_metaclass'} || 'Class::MOP::Method', |
1a7ebbb3 |
60 | } => $class; |
61 | } |
62 | else { |
5f3c057a |
63 | # NOTE: |
64 | # it is safe to use meta here because |
65 | # class will always be a subclass of |
66 | # Class::MOP::Class, which defines meta |
550d56db |
67 | $meta = bless $class->meta->construct_instance(%options) => $class |
1a7ebbb3 |
68 | } |
550d56db |
69 | # and check the metaclass compatibility |
70 | $meta->check_metaclass_compatability(); |
71 | $METAS{$package_name} = $meta; |
72 | } |
73 | |
74 | sub check_metaclass_compatability { |
75 | my $self = shift; |
76 | |
77 | # this is always okay ... |
78 | return if blessed($self) eq 'Class::MOP::Class'; |
79 | |
80 | my @class_list = $self->class_precedence_list; |
81 | shift @class_list; # shift off $self->name |
82 | |
83 | foreach my $class_name (@class_list) { |
84 | next unless $METAS{$class_name}; |
85 | my $meta = $METAS{$class_name}; |
86 | ($self->isa(blessed($meta))) |
87 | || confess $self->name . "->meta => (" . (blessed($self)) . ")" . |
88 | " is not compatible with the " . |
89 | $class_name . "->meta => (" . (blessed($meta)) . ")"; |
90 | } |
bfe4d0fc |
91 | } |
8b978dd5 |
92 | } |
93 | |
94 | sub create { |
95 | my ($class, $package_name, $package_version, %options) = @_; |
bfe4d0fc |
96 | (defined $package_name && $package_name) |
8b978dd5 |
97 | || confess "You must pass a package name"; |
98 | my $code = "package $package_name;"; |
99 | $code .= "\$$package_name\:\:VERSION = '$package_version';" |
100 | if defined $package_version; |
101 | eval $code; |
102 | confess "creation of $package_name failed : $@" if $@; |
bfe4d0fc |
103 | my $meta = $class->initialize($package_name); |
8b978dd5 |
104 | $meta->superclasses(@{$options{superclasses}}) |
105 | if exists $options{superclasses}; |
2eb717d5 |
106 | # NOTE: |
107 | # process attributes first, so that they can |
108 | # install accessors, but locally defined methods |
109 | # can then overwrite them. It is maybe a little odd, but |
110 | # I think this should be the order of things. |
111 | if (exists $options{attributes}) { |
cbd9f942 |
112 | foreach my $attr (@{$options{attributes}}) { |
113 | $meta->add_attribute($attr); |
2eb717d5 |
114 | } |
115 | } |
bfe4d0fc |
116 | if (exists $options{methods}) { |
117 | foreach my $method_name (keys %{$options{methods}}) { |
118 | $meta->add_method($method_name, $options{methods}->{$method_name}); |
119 | } |
2eb717d5 |
120 | } |
8b978dd5 |
121 | return $meta; |
122 | } |
123 | |
7b31baf4 |
124 | ## Attribute readers |
125 | |
126 | # NOTE: |
127 | # all these attribute readers will be bootstrapped |
128 | # away in the Class::MOP bootstrap section |
129 | |
130 | sub name { $_[0]->{'$:package'} } |
131 | sub get_attribute_map { $_[0]->{'%:attributes'} } |
132 | sub attribute_metaclass { $_[0]->{'$:attribute_metaclass'} } |
133 | sub method_metaclass { $_[0]->{'$:method_metaclass'} } |
134 | |
c9e77dbb |
135 | # Instance Construction & Cloning |
136 | |
5f3c057a |
137 | sub new_object { |
138 | my $class = shift; |
651955fb |
139 | # NOTE: |
140 | # we need to protect the integrity of the |
141 | # Class::MOP::Class singletons here, so we |
142 | # delegate this to &construct_class_instance |
143 | # which will deal with the singletons |
144 | return $class->construct_class_instance(@_) |
145 | if $class->name->isa('Class::MOP::Class'); |
5f3c057a |
146 | bless $class->construct_instance(@_) => $class->name; |
147 | } |
e16da3e6 |
148 | |
149 | sub construct_instance { |
cbd9f942 |
150 | my ($class, %params) = @_; |
151 | my $instance = {}; |
c9e77dbb |
152 | foreach my $attr ($class->compute_all_applicable_attributes()) { |
651955fb |
153 | my $init_arg = $attr->init_arg(); |
cbd9f942 |
154 | # try to fetch the init arg from the %params ... |
155 | my $val; |
156 | $val = $params{$init_arg} if exists $params{$init_arg}; |
157 | # if nothing was in the %params, we can use the |
158 | # attribute's default value (if it has one) |
c9e77dbb |
159 | $val ||= $attr->default($instance) if $attr->has_default(); |
cbd9f942 |
160 | $instance->{$attr->name} = $val; |
161 | } |
162 | return $instance; |
e16da3e6 |
163 | } |
164 | |
5f3c057a |
165 | sub clone_object { |
166 | my $class = shift; |
7b31baf4 |
167 | my $instance = shift; |
651955fb |
168 | (blessed($instance) && $instance->isa($class->name)) |
169 | || confess "You must pass an instance ($instance) of the metaclass (" . $class->name . ")"; |
170 | # NOTE: |
171 | # we need to protect the integrity of the |
172 | # Class::MOP::Class singletons here, they |
a740253a |
173 | # should not be cloned. |
651955fb |
174 | return $instance if $instance->isa('Class::MOP::Class'); |
175 | bless $class->clone_instance($instance, @_) => blessed($instance); |
5f3c057a |
176 | } |
177 | |
c9e77dbb |
178 | sub clone_instance { |
651955fb |
179 | my ($class, $instance, %params) = @_; |
180 | (blessed($instance)) |
c9e77dbb |
181 | || confess "You can only clone instances, \$self is not a blessed instance"; |
182 | # NOTE: |
a740253a |
183 | # This will deep clone, which might |
184 | # not be what you always want. So |
185 | # the best thing is to write a more |
186 | # controled &clone method locally |
187 | # in the class (see Class::MOP) |
188 | my $clone = Clone::clone($instance); |
c9e77dbb |
189 | foreach my $attr ($class->compute_all_applicable_attributes()) { |
651955fb |
190 | my $init_arg = $attr->init_arg(); |
c9e77dbb |
191 | # try to fetch the init arg from the %params ... |
192 | $clone->{$attr->name} = $params{$init_arg} |
193 | if exists $params{$init_arg}; |
194 | } |
195 | return $clone; |
196 | } |
197 | |
8b978dd5 |
198 | # Informational |
199 | |
7b31baf4 |
200 | # &name should be here too, but it is above |
201 | # because it gets bootstrapped away |
8b978dd5 |
202 | |
203 | sub version { |
204 | my $self = shift; |
205 | no strict 'refs'; |
206 | ${$self->name . '::VERSION'}; |
207 | } |
208 | |
209 | # Inheritance |
210 | |
211 | sub superclasses { |
212 | my $self = shift; |
213 | no strict 'refs'; |
214 | if (@_) { |
215 | my @supers = @_; |
216 | @{$self->name . '::ISA'} = @supers; |
217 | } |
218 | @{$self->name . '::ISA'}; |
219 | } |
220 | |
221 | sub class_precedence_list { |
222 | my $self = shift; |
bfe4d0fc |
223 | # NOTE: |
224 | # We need to check for ciruclar inheirtance here. |
225 | # This will do nothing if all is well, and blow |
226 | # up otherwise. Yes, it's an ugly hack, better |
227 | # suggestions are welcome. |
228 | { $self->name->isa('This is a test for circular inheritance') } |
229 | # ... and no back to our regularly scheduled program |
8b978dd5 |
230 | ( |
231 | $self->name, |
232 | map { |
bfe4d0fc |
233 | $self->initialize($_)->class_precedence_list() |
8b978dd5 |
234 | } $self->superclasses() |
235 | ); |
236 | } |
237 | |
0882828e |
238 | ## Methods |
239 | |
240 | sub add_method { |
241 | my ($self, $method_name, $method) = @_; |
242 | (defined $method_name && $method_name) |
243 | || confess "You must define a method name"; |
a5eca695 |
244 | # use reftype here to allow for blessed subs ... |
0882828e |
245 | (reftype($method) && reftype($method) eq 'CODE') |
246 | || confess "Your code block must be a CODE reference"; |
247 | my $full_method_name = ($self->name . '::' . $method_name); |
248 | |
249 | no strict 'refs'; |
c9b8b7f9 |
250 | no warnings 'redefine'; |
0882828e |
251 | *{$full_method_name} = subname $full_method_name => $method; |
252 | } |
253 | |
bfe4d0fc |
254 | { |
255 | |
256 | ## private utility functions for has_method |
2eb717d5 |
257 | my $_find_subroutine_package_name = sub { eval { svref_2object($_[0])->GV->STASH->NAME } || '' }; |
258 | my $_find_subroutine_name = sub { eval { svref_2object($_[0])->GV->NAME } || '' }; |
bfe4d0fc |
259 | |
260 | sub has_method { |
c9b8b7f9 |
261 | my ($self, $method_name) = @_; |
bfe4d0fc |
262 | (defined $method_name && $method_name) |
263 | || confess "You must define a method name"; |
0882828e |
264 | |
bfe4d0fc |
265 | my $sub_name = ($self->name . '::' . $method_name); |
0882828e |
266 | |
bfe4d0fc |
267 | no strict 'refs'; |
268 | return 0 if !defined(&{$sub_name}); |
269 | return 0 if $_find_subroutine_package_name->(\&{$sub_name}) ne $self->name && |
270 | $_find_subroutine_name->(\&{$sub_name}) ne '__ANON__'; |
271 | return 1; |
272 | } |
273 | |
0882828e |
274 | } |
275 | |
276 | sub get_method { |
c9b8b7f9 |
277 | my ($self, $method_name) = @_; |
0882828e |
278 | (defined $method_name && $method_name) |
279 | || confess "You must define a method name"; |
280 | |
281 | no strict 'refs'; |
282 | return \&{$self->name . '::' . $method_name} |
bfe4d0fc |
283 | if $self->has_method($method_name); |
c9b8b7f9 |
284 | return; # <- make sure to return undef |
285 | } |
286 | |
287 | sub remove_method { |
288 | my ($self, $method_name) = @_; |
289 | (defined $method_name && $method_name) |
290 | || confess "You must define a method name"; |
291 | |
292 | my $removed_method = $self->get_method($method_name); |
293 | |
294 | no strict 'refs'; |
295 | delete ${$self->name . '::'}{$method_name} |
296 | if defined $removed_method; |
297 | |
298 | return $removed_method; |
299 | } |
300 | |
301 | sub get_method_list { |
302 | my $self = shift; |
303 | no strict 'refs'; |
a5eca695 |
304 | grep { $self->has_method($_) } %{$self->name . '::'}; |
305 | } |
306 | |
307 | sub compute_all_applicable_methods { |
308 | my $self = shift; |
309 | my @methods; |
310 | # keep a record of what we have seen |
311 | # here, this will handle all the |
312 | # inheritence issues because we are |
313 | # using the &class_precedence_list |
314 | my (%seen_class, %seen_method); |
315 | foreach my $class ($self->class_precedence_list()) { |
316 | next if $seen_class{$class}; |
317 | $seen_class{$class}++; |
318 | # fetch the meta-class ... |
319 | my $meta = $self->initialize($class); |
320 | foreach my $method_name ($meta->get_method_list()) { |
321 | next if exists $seen_method{$method_name}; |
322 | $seen_method{$method_name}++; |
323 | push @methods => { |
324 | name => $method_name, |
325 | class => $class, |
326 | code => $meta->get_method($method_name) |
327 | }; |
328 | } |
329 | } |
330 | return @methods; |
331 | } |
332 | |
a5eca695 |
333 | sub find_all_methods_by_name { |
334 | my ($self, $method_name) = @_; |
335 | (defined $method_name && $method_name) |
336 | || confess "You must define a method name to find"; |
337 | my @methods; |
338 | # keep a record of what we have seen |
339 | # here, this will handle all the |
340 | # inheritence issues because we are |
341 | # using the &class_precedence_list |
342 | my %seen_class; |
343 | foreach my $class ($self->class_precedence_list()) { |
344 | next if $seen_class{$class}; |
345 | $seen_class{$class}++; |
346 | # fetch the meta-class ... |
347 | my $meta = $self->initialize($class); |
348 | push @methods => { |
349 | name => $method_name, |
350 | class => $class, |
351 | code => $meta->get_method($method_name) |
352 | } if $meta->has_method($method_name); |
353 | } |
354 | return @methods; |
355 | |
8b978dd5 |
356 | } |
357 | |
552e3d24 |
358 | ## Attributes |
359 | |
e16da3e6 |
360 | sub add_attribute { |
2e41896e |
361 | my $self = shift; |
362 | # either we have an attribute object already |
363 | # or we need to create one from the args provided |
364 | my $attribute = blessed($_[0]) ? $_[0] : $self->attribute_metaclass->new(@_); |
365 | # make sure it is derived from the correct type though |
366 | ($attribute->isa('Class::MOP::Attribute')) |
367 | || confess "Your attribute must be an instance of Class::MOP::Attribute (or a subclass)"; |
9ec169fe |
368 | $attribute->attach_to_class($self); |
369 | $attribute->install_accessors(); |
7b31baf4 |
370 | $self->get_attribute_map->{$attribute->name} = $attribute; |
e16da3e6 |
371 | } |
372 | |
373 | sub has_attribute { |
374 | my ($self, $attribute_name) = @_; |
375 | (defined $attribute_name && $attribute_name) |
376 | || confess "You must define an attribute name"; |
7b31baf4 |
377 | exists $self->get_attribute_map->{$attribute_name} ? 1 : 0; |
e16da3e6 |
378 | } |
379 | |
380 | sub get_attribute { |
381 | my ($self, $attribute_name) = @_; |
382 | (defined $attribute_name && $attribute_name) |
383 | || confess "You must define an attribute name"; |
7b31baf4 |
384 | return $self->get_attribute_map->{$attribute_name} |
e16da3e6 |
385 | if $self->has_attribute($attribute_name); |
386 | } |
387 | |
388 | sub remove_attribute { |
389 | my ($self, $attribute_name) = @_; |
390 | (defined $attribute_name && $attribute_name) |
391 | || confess "You must define an attribute name"; |
7b31baf4 |
392 | my $removed_attribute = $self->get_attribute_map->{$attribute_name}; |
393 | delete $self->get_attribute_map->{$attribute_name} |
9ec169fe |
394 | if defined $removed_attribute; |
395 | $removed_attribute->remove_accessors(); |
396 | $removed_attribute->detach_from_class(); |
e16da3e6 |
397 | return $removed_attribute; |
398 | } |
399 | |
400 | sub get_attribute_list { |
401 | my $self = shift; |
7b31baf4 |
402 | keys %{$self->get_attribute_map}; |
e16da3e6 |
403 | } |
404 | |
405 | sub compute_all_applicable_attributes { |
406 | my $self = shift; |
407 | my @attrs; |
408 | # keep a record of what we have seen |
409 | # here, this will handle all the |
410 | # inheritence issues because we are |
411 | # using the &class_precedence_list |
412 | my (%seen_class, %seen_attr); |
413 | foreach my $class ($self->class_precedence_list()) { |
414 | next if $seen_class{$class}; |
415 | $seen_class{$class}++; |
416 | # fetch the meta-class ... |
417 | my $meta = $self->initialize($class); |
418 | foreach my $attr_name ($meta->get_attribute_list()) { |
419 | next if exists $seen_attr{$attr_name}; |
420 | $seen_attr{$attr_name}++; |
c9e77dbb |
421 | push @attrs => $meta->get_attribute($attr_name); |
e16da3e6 |
422 | } |
423 | } |
424 | return @attrs; |
425 | } |
2eb717d5 |
426 | |
52e8a34c |
427 | # Class attributes |
428 | |
429 | sub add_package_variable { |
430 | my ($self, $variable, $initial_value) = @_; |
431 | (defined $variable && $variable =~ /^[\$\@\%]/) |
432 | || confess "variable name does not have a sigil"; |
433 | |
434 | my ($sigil, $name) = ($variable =~ /^(.)(.*)$/); |
435 | if (defined $initial_value) { |
436 | no strict 'refs'; |
437 | *{$self->name . '::' . $name} = $initial_value; |
438 | } |
439 | else { |
440 | eval $sigil . $self->name . '::' . $name; |
441 | confess "Could not create package variable ($variable) because : $@" if $@; |
442 | } |
443 | } |
444 | |
445 | sub has_package_variable { |
446 | my ($self, $variable) = @_; |
447 | (defined $variable && $variable =~ /^[\$\@\%]/) |
448 | || confess "variable name does not have a sigil"; |
449 | my ($sigil, $name) = ($variable =~ /^(.)(.*)$/); |
450 | no strict 'refs'; |
451 | defined ${$self->name . '::'}{$name} ? 1 : 0; |
452 | } |
453 | |
454 | sub get_package_variable { |
455 | my ($self, $variable) = @_; |
456 | (defined $variable && $variable =~ /^[\$\@\%]/) |
457 | || confess "variable name does not have a sigil"; |
458 | my ($sigil, $name) = ($variable =~ /^(.)(.*)$/); |
459 | no strict 'refs'; |
460 | # try to fetch it first,.. see what happens |
461 | eval '\\' . $sigil . $self->name . '::' . $name; |
462 | confess "Could not get the package variable ($variable) because : $@" if $@; |
463 | # if we didn't die, then we can return it |
464 | # NOTE: |
465 | # this is not ideal, better suggestions are welcome |
466 | eval '\\' . $sigil . $self->name . '::' . $name; |
467 | } |
468 | |
469 | sub remove_package_variable { |
470 | my ($self, $variable) = @_; |
471 | (defined $variable && $variable =~ /^[\$\@\%]/) |
472 | || confess "variable name does not have a sigil"; |
473 | my ($sigil, $name) = ($variable =~ /^(.)(.*)$/); |
474 | no strict 'refs'; |
475 | delete ${$self->name . '::'}{$name}; |
476 | } |
477 | |
8b978dd5 |
478 | 1; |
479 | |
480 | __END__ |
481 | |
482 | =pod |
483 | |
484 | =head1 NAME |
485 | |
486 | Class::MOP::Class - Class Meta Object |
487 | |
488 | =head1 SYNOPSIS |
489 | |
fe122940 |
490 | # use this for introspection ... |
491 | |
492 | package Foo; |
493 | sub meta { Class::MOP::Class->initialize(__PACKAGE__) } |
494 | |
495 | # elsewhere in the code ... |
496 | |
497 | # add a method to Foo ... |
498 | Foo->meta->add_method('bar' => sub { ... }) |
499 | |
500 | # get a list of all the classes searched |
501 | # the method dispatcher in the correct order |
502 | Foo->meta->class_precedence_list() |
503 | |
504 | # remove a method from Foo |
505 | Foo->meta->remove_method('bar'); |
506 | |
507 | # or use this to actually create classes ... |
508 | |
509 | Class::MOP::Class->create('Bar' => '0.01' => ( |
510 | superclasses => [ 'Foo' ], |
511 | attributes => [ |
512 | Class::MOP:::Attribute->new('$bar'), |
513 | Class::MOP:::Attribute->new('$baz'), |
514 | ], |
515 | methods => { |
516 | calculate_bar => sub { ... }, |
517 | construct_baz => sub { ... } |
518 | } |
519 | )); |
520 | |
8b978dd5 |
521 | =head1 DESCRIPTION |
522 | |
fe122940 |
523 | This is the largest and currently most complex part of the Perl 5 |
524 | meta-object protocol. It controls the introspection and |
525 | manipulation of Perl 5 classes (and it can create them too). The |
526 | best way to understand what this module can do, is to read the |
527 | documentation for each of it's methods. |
528 | |
552e3d24 |
529 | =head1 METHODS |
530 | |
2eb717d5 |
531 | =head2 Self Introspection |
532 | |
533 | =over 4 |
534 | |
535 | =item B<meta> |
536 | |
fe122940 |
537 | This will return a B<Class::MOP::Class> instance which is related |
538 | to this class. Thereby allowing B<Class::MOP::Class> to actually |
539 | introspect itself. |
540 | |
541 | As with B<Class::MOP::Attribute>, B<Class::MOP> will actually |
542 | bootstrap this module by installing a number of attribute meta-objects |
543 | into it's metaclass. This will allow this class to reap all the benifits |
544 | of the MOP when subclassing it. |
2eb717d5 |
545 | |
546 | =back |
547 | |
552e3d24 |
548 | =head2 Class construction |
549 | |
a2e85e6c |
550 | These methods will handle creating B<Class::MOP::Class> objects, |
551 | which can be used to both create new classes, and analyze |
552 | pre-existing classes. |
552e3d24 |
553 | |
554 | This module will internally store references to all the instances |
555 | you create with these methods, so that they do not need to be |
556 | created any more than nessecary. Basically, they are singletons. |
557 | |
558 | =over 4 |
559 | |
560 | =item B<create ($package_name, ?$package_version, |
a2e85e6c |
561 | superclasses =E<gt> ?@superclasses, |
562 | methods =E<gt> ?%methods, |
563 | attributes =E<gt> ?%attributes)> |
552e3d24 |
564 | |
a2e85e6c |
565 | This returns a B<Class::MOP::Class> object, bringing the specified |
552e3d24 |
566 | C<$package_name> into existence and adding any of the |
567 | C<$package_version>, C<@superclasses>, C<%methods> and C<%attributes> |
568 | to it. |
569 | |
570 | =item B<initialize ($package_name)> |
571 | |
a2e85e6c |
572 | This initializes and returns returns a B<Class::MOP::Class> object |
573 | for a given a C<$package_name>. |
574 | |
651955fb |
575 | =item B<construct_class_instance (%options)> |
a2e85e6c |
576 | |
577 | This will construct an instance of B<Class::MOP::Class>, it is |
578 | here so that we can actually "tie the knot" for B<Class::MOP::Class> |
579 | to use C<construct_instance> once all the bootstrapping is done. This |
580 | method is used internally by C<initialize> and should never be called |
581 | from outside of that method really. |
552e3d24 |
582 | |
550d56db |
583 | =item B<check_metaclass_compatability> |
584 | |
585 | This method is called as the very last thing in the |
586 | C<construct_class_instance> method. This will check that the |
587 | metaclass you are creating is compatible with the metaclasses of all |
588 | your ancestors. For more inforamtion about metaclass compatibility |
589 | see the C<About Metaclass compatibility> section in L<Class::MOP>. |
590 | |
552e3d24 |
591 | =back |
592 | |
c9e77dbb |
593 | =head2 Object instance construction and cloning |
a2e85e6c |
594 | |
c9e77dbb |
595 | These methods are B<entirely optional>, it is up to you whether you want |
596 | to use them or not. |
552e3d24 |
597 | |
598 | =over 4 |
599 | |
5f3c057a |
600 | =item B<new_object (%params)> |
601 | |
602 | This is a convience method for creating a new object of the class, and |
603 | blessing it into the appropriate package as well. Ideally your class |
604 | would call a C<new> this method like so: |
605 | |
606 | sub MyClass::new { |
607 | my ($class, %param) = @_; |
608 | $class->meta->new_object(%params); |
609 | } |
610 | |
611 | Of course the ideal place for this would actually be in C<UNIVERSAL::> |
612 | but that is considered bad style, so we do not do that. |
613 | |
cbd9f942 |
614 | =item B<construct_instance (%params)> |
552e3d24 |
615 | |
c9e77dbb |
616 | This method is used to construct an instace structure suitable for |
617 | C<bless>-ing into your package of choice. It works in conjunction |
618 | with the Attribute protocol to collect all applicable attributes. |
619 | |
cbd9f942 |
620 | This will construct and instance using a HASH ref as storage |
552e3d24 |
621 | (currently only HASH references are supported). This will collect all |
a2e85e6c |
622 | the applicable attributes and layout out the fields in the HASH ref, |
623 | it will then initialize them using either use the corresponding key |
624 | in C<%params> or any default value or initializer found in the |
625 | attribute meta-object. |
727919c5 |
626 | |
5f3c057a |
627 | =item B<clone_object ($instance, %params)> |
628 | |
629 | This is a convience method for cloning an object instance, then |
630 | blessing it into the appropriate package. Ideally your class |
631 | would call a C<clone> this method like so: |
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($instance, %params)> |
642 | |
643 | This method is a compliment of C<construct_instance> (which means if |
644 | you override C<construct_instance>, you need to override this one too). |
645 | |
646 | This method will clone the C<$instance> structure created by the |
647 | C<construct_instance> method, and apply any C<%params> passed to it |
648 | to change the attribute values. The structure returned is (like with |
649 | C<construct_instance>) an unC<bless>ed HASH reference, it is your |
650 | responsibility to then bless this cloned structure into the right |
651 | class. |
652 | |
552e3d24 |
653 | =back |
654 | |
655 | =head2 Informational |
656 | |
657 | =over 4 |
658 | |
659 | =item B<name> |
660 | |
a2e85e6c |
661 | This is a read-only attribute which returns the package name for the |
662 | given B<Class::MOP::Class> instance. |
552e3d24 |
663 | |
664 | =item B<version> |
665 | |
666 | This is a read-only attribute which returns the C<$VERSION> of the |
a2e85e6c |
667 | package for the given B<Class::MOP::Class> instance. |
552e3d24 |
668 | |
669 | =back |
670 | |
671 | =head2 Inheritance Relationships |
672 | |
673 | =over 4 |
674 | |
675 | =item B<superclasses (?@superclasses)> |
676 | |
677 | This is a read-write attribute which represents the superclass |
a2e85e6c |
678 | relationships of the class the B<Class::MOP::Class> instance is |
679 | associated with. Basically, it can get and set the C<@ISA> for you. |
552e3d24 |
680 | |
343203ee |
681 | B<NOTE:> |
682 | Perl will occasionally perform some C<@ISA> and method caching, if |
683 | you decide to change your superclass relationship at runtime (which |
684 | is quite insane and very much not recommened), then you should be |
685 | aware of this and the fact that this module does not make any |
686 | attempt to address this issue. |
687 | |
552e3d24 |
688 | =item B<class_precedence_list> |
689 | |
a2e85e6c |
690 | This computes the a list of all the class's ancestors in the same order |
691 | in which method dispatch will be done. This is similair to |
692 | what B<Class::ISA::super_path> does, but we don't remove duplicate names. |
552e3d24 |
693 | |
694 | =back |
695 | |
696 | =head2 Methods |
697 | |
698 | =over 4 |
699 | |
2e41896e |
700 | =item B<method_metaclass> |
701 | |
552e3d24 |
702 | =item B<add_method ($method_name, $method)> |
703 | |
704 | This will take a C<$method_name> and CODE reference to that |
a2e85e6c |
705 | C<$method> and install it into the class's package. |
552e3d24 |
706 | |
a2e85e6c |
707 | B<NOTE>: |
708 | This does absolutely nothing special to C<$method> |
552e3d24 |
709 | other than use B<Sub::Name> to make sure it is tagged with the |
710 | correct name, and therefore show up correctly in stack traces and |
711 | such. |
712 | |
713 | =item B<has_method ($method_name)> |
714 | |
a2e85e6c |
715 | This just provides a simple way to check if the class implements |
552e3d24 |
716 | a specific C<$method_name>. It will I<not> however, attempt to check |
a2e85e6c |
717 | if the class inherits the method (use C<UNIVERSAL::can> for that). |
552e3d24 |
718 | |
719 | This will correctly handle functions defined outside of the package |
720 | that use a fully qualified name (C<sub Package::name { ... }>). |
721 | |
722 | This will correctly handle functions renamed with B<Sub::Name> and |
723 | installed using the symbol tables. However, if you are naming the |
724 | subroutine outside of the package scope, you must use the fully |
725 | qualified name, including the package name, for C<has_method> to |
726 | correctly identify it. |
727 | |
728 | This will attempt to correctly ignore functions imported from other |
729 | packages using B<Exporter>. It breaks down if the function imported |
730 | is an C<__ANON__> sub (such as with C<use constant>), which very well |
731 | may be a valid method being applied to the class. |
732 | |
733 | In short, this method cannot always be trusted to determine if the |
734 | C<$method_name> is actually a method. However, it will DWIM about |
a2e85e6c |
735 | 90% of the time, so it's a small trade off I think. |
552e3d24 |
736 | |
737 | =item B<get_method ($method_name)> |
738 | |
739 | This will return a CODE reference of the specified C<$method_name>, |
740 | or return undef if that method does not exist. |
741 | |
742 | =item B<remove_method ($method_name)> |
743 | |
a2e85e6c |
744 | This will attempt to remove a given C<$method_name> from the class. |
552e3d24 |
745 | It will return the CODE reference that it has removed, and will |
746 | attempt to use B<Sub::Name> to clear the methods associated name. |
747 | |
748 | =item B<get_method_list> |
749 | |
750 | This will return a list of method names for all I<locally> defined |
751 | methods. It does B<not> provide a list of all applicable methods, |
752 | including any inherited ones. If you want a list of all applicable |
753 | methods, use the C<compute_all_applicable_methods> method. |
754 | |
755 | =item B<compute_all_applicable_methods> |
756 | |
a2e85e6c |
757 | This will return a list of all the methods names this class will |
758 | respond to, taking into account inheritance. The list will be a list of |
552e3d24 |
759 | HASH references, each one containing the following information; method |
760 | name, the name of the class in which the method lives and a CODE |
761 | reference for the actual method. |
762 | |
763 | =item B<find_all_methods_by_name ($method_name)> |
764 | |
765 | This will traverse the inheritence hierarchy and locate all methods |
766 | with a given C<$method_name>. Similar to |
767 | C<compute_all_applicable_methods> it returns a list of HASH references |
768 | with the following information; method name (which will always be the |
769 | same as C<$method_name>), the name of the class in which the method |
770 | lives and a CODE reference for the actual method. |
771 | |
772 | The list of methods produced is a distinct list, meaning there are no |
773 | duplicates in it. This is especially useful for things like object |
774 | initialization and destruction where you only want the method called |
775 | once, and in the correct order. |
776 | |
777 | =back |
778 | |
779 | =head2 Attributes |
780 | |
781 | It should be noted that since there is no one consistent way to define |
782 | the attributes of a class in Perl 5. These methods can only work with |
783 | the information given, and can not easily discover information on |
a2e85e6c |
784 | their own. See L<Class::MOP::Attribute> for more details. |
552e3d24 |
785 | |
786 | =over 4 |
787 | |
2e41896e |
788 | =item B<attribute_metaclass> |
789 | |
7b31baf4 |
790 | =item B<get_attribute_map> |
791 | |
552e3d24 |
792 | =item B<add_attribute ($attribute_name, $attribute_meta_object)> |
793 | |
a2e85e6c |
794 | This stores a C<$attribute_meta_object> in the B<Class::MOP::Class> |
795 | instance associated with the given class, and associates it with |
796 | the C<$attribute_name>. Unlike methods, attributes within the MOP |
797 | are stored as meta-information only. They will be used later to |
798 | construct instances from (see C<construct_instance> above). |
552e3d24 |
799 | More details about the attribute meta-objects can be found in the |
a2e85e6c |
800 | L<Class::MOP::Attribute> or the L<Class::MOP/The Attribute protocol> |
801 | section. |
802 | |
803 | It should be noted that any accessor, reader/writer or predicate |
804 | methods which the C<$attribute_meta_object> has will be installed |
805 | into the class at this time. |
552e3d24 |
806 | |
807 | =item B<has_attribute ($attribute_name)> |
808 | |
a2e85e6c |
809 | Checks to see if this class has an attribute by the name of |
552e3d24 |
810 | C<$attribute_name> and returns a boolean. |
811 | |
812 | =item B<get_attribute ($attribute_name)> |
813 | |
814 | Returns the attribute meta-object associated with C<$attribute_name>, |
815 | if none is found, it will return undef. |
816 | |
817 | =item B<remove_attribute ($attribute_name)> |
818 | |
819 | This will remove the attribute meta-object stored at |
820 | C<$attribute_name>, then return the removed attribute meta-object. |
821 | |
a2e85e6c |
822 | B<NOTE:> |
823 | Removing an attribute will only affect future instances of |
552e3d24 |
824 | the class, it will not make any attempt to remove the attribute from |
825 | any existing instances of the class. |
826 | |
a2e85e6c |
827 | It should be noted that any accessor, reader/writer or predicate |
828 | methods which the attribute meta-object stored at C<$attribute_name> |
829 | has will be removed from the class at this time. This B<will> make |
830 | these attributes somewhat inaccessable in previously created |
831 | instances. But if you are crazy enough to do this at runtime, then |
832 | you are crazy enough to deal with something like this :). |
833 | |
552e3d24 |
834 | =item B<get_attribute_list> |
835 | |
836 | This returns a list of attribute names which are defined in the local |
837 | class. If you want a list of all applicable attributes for a class, |
838 | use the C<compute_all_applicable_attributes> method. |
839 | |
840 | =item B<compute_all_applicable_attributes> |
841 | |
c9e77dbb |
842 | This will traverse the inheritance heirachy and return a list of all |
843 | the applicable attributes for this class. It does not construct a |
844 | HASH reference like C<compute_all_applicable_methods> because all |
845 | that same information is discoverable through the attribute |
846 | meta-object itself. |
552e3d24 |
847 | |
848 | =back |
849 | |
52e8a34c |
850 | =head2 Package Variables |
851 | |
852 | Since Perl's classes are built atop the Perl package system, it is |
853 | fairly common to use package scoped variables for things like static |
854 | class variables. The following methods are convience methods for |
855 | the creation and inspection of package scoped variables. |
856 | |
857 | =over 4 |
858 | |
859 | =item B<add_package_variable ($variable_name, ?$initial_value)> |
860 | |
861 | Given a C<$variable_name>, which must contain a leading sigil, this |
862 | method will create that variable within the package which houses the |
863 | class. It also takes an optional C<$initial_value>, which must be a |
864 | reference of the same type as the sigil of the C<$variable_name> |
865 | implies. |
866 | |
867 | =item B<get_package_variable ($variable_name)> |
868 | |
869 | This will return a reference to the package variable in |
870 | C<$variable_name>. |
871 | |
872 | =item B<has_package_variable ($variable_name)> |
873 | |
874 | Returns true (C<1>) if there is a package variable defined for |
875 | C<$variable_name>, and false (C<0>) otherwise. |
876 | |
877 | =item B<remove_package_variable ($variable_name)> |
878 | |
879 | This will attempt to remove the package variable at C<$variable_name>. |
880 | |
881 | =back |
882 | |
8b978dd5 |
883 | =head1 AUTHOR |
884 | |
a2e85e6c |
885 | Stevan Little E<lt>stevan@iinteractive.comE<gt> |
8b978dd5 |
886 | |
887 | =head1 COPYRIGHT AND LICENSE |
888 | |
889 | Copyright 2006 by Infinity Interactive, Inc. |
890 | |
891 | L<http://www.iinteractive.com> |
892 | |
893 | This library is free software; you can redistribute it and/or modify |
894 | it under the same terms as Perl itself. |
895 | |
896 | =cut |