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'; |
5659d76e |
9 | use Hash::Util 'lock_keys'; |
8b978dd5 |
10 | use Sub::Name 'subname'; |
11 | use B 'svref_2object'; |
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) || $class; |
52 | if ($class =~ /^Class::MOP::/) { |
651955fb |
53 | $METAS{$package_name} = bless { |
351bd7d4 |
54 | '$:package' => $package_name, |
55 | '%:attributes' => {}, |
56 | '$:attribute_metaclass' => 'Class::MOP::Attribute', |
57 | '$: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 |
651955fb |
65 | $METAS{$package_name} = bless $class->meta->construct_instance(%options) => $class |
1a7ebbb3 |
66 | } |
bfe4d0fc |
67 | } |
8b978dd5 |
68 | } |
69 | |
70 | sub create { |
71 | my ($class, $package_name, $package_version, %options) = @_; |
bfe4d0fc |
72 | (defined $package_name && $package_name) |
8b978dd5 |
73 | || confess "You must pass a package name"; |
74 | my $code = "package $package_name;"; |
75 | $code .= "\$$package_name\:\:VERSION = '$package_version';" |
76 | if defined $package_version; |
77 | eval $code; |
78 | confess "creation of $package_name failed : $@" if $@; |
bfe4d0fc |
79 | my $meta = $class->initialize($package_name); |
8b978dd5 |
80 | $meta->superclasses(@{$options{superclasses}}) |
81 | if exists $options{superclasses}; |
2eb717d5 |
82 | # NOTE: |
83 | # process attributes first, so that they can |
84 | # install accessors, but locally defined methods |
85 | # can then overwrite them. It is maybe a little odd, but |
86 | # I think this should be the order of things. |
87 | if (exists $options{attributes}) { |
cbd9f942 |
88 | foreach my $attr (@{$options{attributes}}) { |
89 | $meta->add_attribute($attr); |
2eb717d5 |
90 | } |
91 | } |
bfe4d0fc |
92 | if (exists $options{methods}) { |
93 | foreach my $method_name (keys %{$options{methods}}) { |
94 | $meta->add_method($method_name, $options{methods}->{$method_name}); |
95 | } |
2eb717d5 |
96 | } |
8b978dd5 |
97 | return $meta; |
98 | } |
99 | |
7b31baf4 |
100 | ## Attribute readers |
101 | |
102 | # NOTE: |
103 | # all these attribute readers will be bootstrapped |
104 | # away in the Class::MOP bootstrap section |
105 | |
106 | sub name { $_[0]->{'$:package'} } |
107 | sub get_attribute_map { $_[0]->{'%:attributes'} } |
108 | sub attribute_metaclass { $_[0]->{'$:attribute_metaclass'} } |
109 | sub method_metaclass { $_[0]->{'$:method_metaclass'} } |
110 | |
c9e77dbb |
111 | # Instance Construction & Cloning |
112 | |
5f3c057a |
113 | sub new_object { |
114 | my $class = shift; |
651955fb |
115 | # NOTE: |
116 | # we need to protect the integrity of the |
117 | # Class::MOP::Class singletons here, so we |
118 | # delegate this to &construct_class_instance |
119 | # which will deal with the singletons |
120 | return $class->construct_class_instance(@_) |
121 | if $class->name->isa('Class::MOP::Class'); |
5f3c057a |
122 | bless $class->construct_instance(@_) => $class->name; |
123 | } |
e16da3e6 |
124 | |
125 | sub construct_instance { |
cbd9f942 |
126 | my ($class, %params) = @_; |
127 | my $instance = {}; |
c9e77dbb |
128 | foreach my $attr ($class->compute_all_applicable_attributes()) { |
651955fb |
129 | my $init_arg = $attr->init_arg(); |
cbd9f942 |
130 | # try to fetch the init arg from the %params ... |
131 | my $val; |
132 | $val = $params{$init_arg} if exists $params{$init_arg}; |
133 | # if nothing was in the %params, we can use the |
134 | # attribute's default value (if it has one) |
c9e77dbb |
135 | $val ||= $attr->default($instance) if $attr->has_default(); |
cbd9f942 |
136 | $instance->{$attr->name} = $val; |
137 | } |
138 | return $instance; |
e16da3e6 |
139 | } |
140 | |
5f3c057a |
141 | sub clone_object { |
142 | my $class = shift; |
7b31baf4 |
143 | my $instance = shift; |
651955fb |
144 | (blessed($instance) && $instance->isa($class->name)) |
145 | || confess "You must pass an instance ($instance) of the metaclass (" . $class->name . ")"; |
146 | # NOTE: |
147 | # we need to protect the integrity of the |
148 | # Class::MOP::Class singletons here, they |
149 | # should not be cloned |
150 | return $instance if $instance->isa('Class::MOP::Class'); |
151 | bless $class->clone_instance($instance, @_) => blessed($instance); |
5f3c057a |
152 | } |
153 | |
5659d76e |
154 | #{ |
155 | # sub _deep_clone { |
156 | # my ($object, $cache) = @_; |
157 | # return $object unless ref($object); |
158 | # # check for an active cache |
159 | # return _deep_clone_ref($object, ($cache = {}), 'HASH') if not defined $cache; |
160 | # # if we have it in the cache them return the cached clone |
161 | # return $cache->{$object} if exists $cache->{$object}; |
162 | # # now try it as an object, which will in |
163 | # # turn try it as ref if its not an object |
164 | # # and store it in case we run into a circular ref |
165 | # $cache->{$object} = _deep_clone_object($object, $cache); |
166 | # } |
167 | # |
168 | # sub _deep_clone_object { |
169 | # my ($object, $cache) = @_; |
170 | # # check to see if its an object, with a clone method |
171 | # # or if we have an object, with no clone method, then |
172 | # # we will respect its encapsulation, and not muck with |
173 | # # its internals. Basically, we assume it does not want |
174 | # # to be cloned |
175 | # return $cache->{$object} = ($object->can('clone') ? $object->clone() : $object) |
176 | # if blessed($object); |
177 | # return $cache->{$object} = _deep_clone_ref($object, $cache); |
178 | # } |
179 | # |
180 | # sub _deep_clone_ref { |
181 | # my ($object, $cache, $ref_type) = @_; |
182 | # $ref_type ||= ref($object); |
183 | # my ($clone, $tied); |
184 | # if ($ref_type eq 'HASH') { |
185 | # $clone = {}; |
186 | # tie %{$clone}, ref $tied if $tied = tied(%{$object}); |
187 | # %{$clone} = map { ref($_) ? _deep_clone($_, $cache) : $_ } %{$object}; |
188 | # } |
189 | # elsif ($ref_type eq 'ARRAY') { |
190 | # $clone = []; |
191 | # tie @{$clone}, ref $tied if $tied = tied(@{$object}); |
192 | # @{$clone} = map { ref($_) ? _deep_clone($_, $cache) : $_ } @{$object}; |
193 | # } |
194 | # elsif ($ref_type eq 'REF' or $ref_type eq 'SCALAR') { |
195 | # my $var = ""; |
196 | # $clone = \$var; |
197 | # tie ${$clone}, ref $tied if $tied = tied(${$object}); |
198 | # ${$clone} = _deep_clone(${$object}, $cache); |
199 | # } |
200 | # else { |
201 | # # shallow copy reference to code, glob, regex |
202 | # $clone = $object; |
203 | # } |
204 | # # store it in our cache |
205 | # $cache->{$object} = $clone; |
206 | # # and return the clone |
207 | # return $clone; |
208 | # } |
209 | #} |
210 | |
c9e77dbb |
211 | sub clone_instance { |
651955fb |
212 | my ($class, $instance, %params) = @_; |
213 | (blessed($instance)) |
c9e77dbb |
214 | || confess "You can only clone instances, \$self is not a blessed instance"; |
215 | # NOTE: |
216 | # this should actually do a deep clone |
217 | # instead of this cheap hack. I will |
218 | # add that in later. |
219 | # (use the Class::Cloneable::Util code) |
5659d76e |
220 | my $clone = { %{$instance} }; #_deep_clone($instance); |
c9e77dbb |
221 | foreach my $attr ($class->compute_all_applicable_attributes()) { |
651955fb |
222 | my $init_arg = $attr->init_arg(); |
c9e77dbb |
223 | # try to fetch the init arg from the %params ... |
224 | $clone->{$attr->name} = $params{$init_arg} |
225 | if exists $params{$init_arg}; |
226 | } |
227 | return $clone; |
228 | } |
229 | |
8b978dd5 |
230 | # Informational |
231 | |
7b31baf4 |
232 | # &name should be here too, but it is above |
233 | # because it gets bootstrapped away |
8b978dd5 |
234 | |
235 | sub version { |
236 | my $self = shift; |
237 | no strict 'refs'; |
238 | ${$self->name . '::VERSION'}; |
239 | } |
240 | |
241 | # Inheritance |
242 | |
243 | sub superclasses { |
244 | my $self = shift; |
245 | no strict 'refs'; |
246 | if (@_) { |
247 | my @supers = @_; |
248 | @{$self->name . '::ISA'} = @supers; |
249 | } |
250 | @{$self->name . '::ISA'}; |
251 | } |
252 | |
253 | sub class_precedence_list { |
254 | my $self = shift; |
bfe4d0fc |
255 | # NOTE: |
256 | # We need to check for ciruclar inheirtance here. |
257 | # This will do nothing if all is well, and blow |
258 | # up otherwise. Yes, it's an ugly hack, better |
259 | # suggestions are welcome. |
260 | { $self->name->isa('This is a test for circular inheritance') } |
261 | # ... and no back to our regularly scheduled program |
8b978dd5 |
262 | ( |
263 | $self->name, |
264 | map { |
bfe4d0fc |
265 | $self->initialize($_)->class_precedence_list() |
8b978dd5 |
266 | } $self->superclasses() |
267 | ); |
268 | } |
269 | |
0882828e |
270 | ## Methods |
271 | |
272 | sub add_method { |
273 | my ($self, $method_name, $method) = @_; |
274 | (defined $method_name && $method_name) |
275 | || confess "You must define a method name"; |
a5eca695 |
276 | # use reftype here to allow for blessed subs ... |
0882828e |
277 | (reftype($method) && reftype($method) eq 'CODE') |
278 | || confess "Your code block must be a CODE reference"; |
279 | my $full_method_name = ($self->name . '::' . $method_name); |
280 | |
281 | no strict 'refs'; |
c9b8b7f9 |
282 | no warnings 'redefine'; |
0882828e |
283 | *{$full_method_name} = subname $full_method_name => $method; |
284 | } |
285 | |
bfe4d0fc |
286 | { |
287 | |
288 | ## private utility functions for has_method |
2eb717d5 |
289 | my $_find_subroutine_package_name = sub { eval { svref_2object($_[0])->GV->STASH->NAME } || '' }; |
290 | my $_find_subroutine_name = sub { eval { svref_2object($_[0])->GV->NAME } || '' }; |
bfe4d0fc |
291 | |
292 | sub has_method { |
c9b8b7f9 |
293 | my ($self, $method_name) = @_; |
bfe4d0fc |
294 | (defined $method_name && $method_name) |
295 | || confess "You must define a method name"; |
0882828e |
296 | |
bfe4d0fc |
297 | my $sub_name = ($self->name . '::' . $method_name); |
0882828e |
298 | |
bfe4d0fc |
299 | no strict 'refs'; |
300 | return 0 if !defined(&{$sub_name}); |
301 | return 0 if $_find_subroutine_package_name->(\&{$sub_name}) ne $self->name && |
302 | $_find_subroutine_name->(\&{$sub_name}) ne '__ANON__'; |
303 | return 1; |
304 | } |
305 | |
0882828e |
306 | } |
307 | |
308 | sub get_method { |
c9b8b7f9 |
309 | my ($self, $method_name) = @_; |
0882828e |
310 | (defined $method_name && $method_name) |
311 | || confess "You must define a method name"; |
312 | |
313 | no strict 'refs'; |
314 | return \&{$self->name . '::' . $method_name} |
bfe4d0fc |
315 | if $self->has_method($method_name); |
c9b8b7f9 |
316 | return; # <- make sure to return undef |
317 | } |
318 | |
319 | sub remove_method { |
320 | my ($self, $method_name) = @_; |
321 | (defined $method_name && $method_name) |
322 | || confess "You must define a method name"; |
323 | |
324 | my $removed_method = $self->get_method($method_name); |
325 | |
326 | no strict 'refs'; |
327 | delete ${$self->name . '::'}{$method_name} |
328 | if defined $removed_method; |
329 | |
330 | return $removed_method; |
331 | } |
332 | |
333 | sub get_method_list { |
334 | my $self = shift; |
335 | no strict 'refs'; |
a5eca695 |
336 | grep { $self->has_method($_) } %{$self->name . '::'}; |
337 | } |
338 | |
339 | sub compute_all_applicable_methods { |
340 | my $self = shift; |
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, %seen_method); |
347 | foreach my $class ($self->class_precedence_list()) { |
348 | next if $seen_class{$class}; |
349 | $seen_class{$class}++; |
350 | # fetch the meta-class ... |
351 | my $meta = $self->initialize($class); |
352 | foreach my $method_name ($meta->get_method_list()) { |
353 | next if exists $seen_method{$method_name}; |
354 | $seen_method{$method_name}++; |
355 | push @methods => { |
356 | name => $method_name, |
357 | class => $class, |
358 | code => $meta->get_method($method_name) |
359 | }; |
360 | } |
361 | } |
362 | return @methods; |
363 | } |
364 | |
a5eca695 |
365 | sub find_all_methods_by_name { |
366 | my ($self, $method_name) = @_; |
367 | (defined $method_name && $method_name) |
368 | || confess "You must define a method name to find"; |
369 | my @methods; |
370 | # keep a record of what we have seen |
371 | # here, this will handle all the |
372 | # inheritence issues because we are |
373 | # using the &class_precedence_list |
374 | my %seen_class; |
375 | foreach my $class ($self->class_precedence_list()) { |
376 | next if $seen_class{$class}; |
377 | $seen_class{$class}++; |
378 | # fetch the meta-class ... |
379 | my $meta = $self->initialize($class); |
380 | push @methods => { |
381 | name => $method_name, |
382 | class => $class, |
383 | code => $meta->get_method($method_name) |
384 | } if $meta->has_method($method_name); |
385 | } |
386 | return @methods; |
387 | |
8b978dd5 |
388 | } |
389 | |
552e3d24 |
390 | ## Attributes |
391 | |
e16da3e6 |
392 | sub add_attribute { |
2e41896e |
393 | my $self = shift; |
394 | # either we have an attribute object already |
395 | # or we need to create one from the args provided |
396 | my $attribute = blessed($_[0]) ? $_[0] : $self->attribute_metaclass->new(@_); |
397 | # make sure it is derived from the correct type though |
398 | ($attribute->isa('Class::MOP::Attribute')) |
399 | || confess "Your attribute must be an instance of Class::MOP::Attribute (or a subclass)"; |
9ec169fe |
400 | $attribute->attach_to_class($self); |
401 | $attribute->install_accessors(); |
7b31baf4 |
402 | $self->get_attribute_map->{$attribute->name} = $attribute; |
e16da3e6 |
403 | } |
404 | |
405 | sub has_attribute { |
406 | my ($self, $attribute_name) = @_; |
407 | (defined $attribute_name && $attribute_name) |
408 | || confess "You must define an attribute name"; |
7b31baf4 |
409 | exists $self->get_attribute_map->{$attribute_name} ? 1 : 0; |
e16da3e6 |
410 | } |
411 | |
412 | sub get_attribute { |
413 | my ($self, $attribute_name) = @_; |
414 | (defined $attribute_name && $attribute_name) |
415 | || confess "You must define an attribute name"; |
7b31baf4 |
416 | return $self->get_attribute_map->{$attribute_name} |
e16da3e6 |
417 | if $self->has_attribute($attribute_name); |
418 | } |
419 | |
420 | sub remove_attribute { |
421 | my ($self, $attribute_name) = @_; |
422 | (defined $attribute_name && $attribute_name) |
423 | || confess "You must define an attribute name"; |
7b31baf4 |
424 | my $removed_attribute = $self->get_attribute_map->{$attribute_name}; |
425 | delete $self->get_attribute_map->{$attribute_name} |
9ec169fe |
426 | if defined $removed_attribute; |
427 | $removed_attribute->remove_accessors(); |
428 | $removed_attribute->detach_from_class(); |
e16da3e6 |
429 | return $removed_attribute; |
430 | } |
431 | |
432 | sub get_attribute_list { |
433 | my $self = shift; |
7b31baf4 |
434 | keys %{$self->get_attribute_map}; |
e16da3e6 |
435 | } |
436 | |
437 | sub compute_all_applicable_attributes { |
438 | my $self = shift; |
439 | my @attrs; |
440 | # keep a record of what we have seen |
441 | # here, this will handle all the |
442 | # inheritence issues because we are |
443 | # using the &class_precedence_list |
444 | my (%seen_class, %seen_attr); |
445 | foreach my $class ($self->class_precedence_list()) { |
446 | next if $seen_class{$class}; |
447 | $seen_class{$class}++; |
448 | # fetch the meta-class ... |
449 | my $meta = $self->initialize($class); |
450 | foreach my $attr_name ($meta->get_attribute_list()) { |
451 | next if exists $seen_attr{$attr_name}; |
452 | $seen_attr{$attr_name}++; |
c9e77dbb |
453 | push @attrs => $meta->get_attribute($attr_name); |
e16da3e6 |
454 | } |
455 | } |
456 | return @attrs; |
457 | } |
2eb717d5 |
458 | |
52e8a34c |
459 | # Class attributes |
460 | |
461 | sub add_package_variable { |
462 | my ($self, $variable, $initial_value) = @_; |
463 | (defined $variable && $variable =~ /^[\$\@\%]/) |
464 | || confess "variable name does not have a sigil"; |
465 | |
466 | my ($sigil, $name) = ($variable =~ /^(.)(.*)$/); |
467 | if (defined $initial_value) { |
468 | no strict 'refs'; |
469 | *{$self->name . '::' . $name} = $initial_value; |
470 | } |
471 | else { |
472 | eval $sigil . $self->name . '::' . $name; |
473 | confess "Could not create package variable ($variable) because : $@" if $@; |
474 | } |
475 | } |
476 | |
477 | sub has_package_variable { |
478 | my ($self, $variable) = @_; |
479 | (defined $variable && $variable =~ /^[\$\@\%]/) |
480 | || confess "variable name does not have a sigil"; |
481 | my ($sigil, $name) = ($variable =~ /^(.)(.*)$/); |
482 | no strict 'refs'; |
483 | defined ${$self->name . '::'}{$name} ? 1 : 0; |
484 | } |
485 | |
486 | sub get_package_variable { |
487 | my ($self, $variable) = @_; |
488 | (defined $variable && $variable =~ /^[\$\@\%]/) |
489 | || confess "variable name does not have a sigil"; |
490 | my ($sigil, $name) = ($variable =~ /^(.)(.*)$/); |
491 | no strict 'refs'; |
492 | # try to fetch it first,.. see what happens |
493 | eval '\\' . $sigil . $self->name . '::' . $name; |
494 | confess "Could not get the package variable ($variable) because : $@" if $@; |
495 | # if we didn't die, then we can return it |
496 | # NOTE: |
497 | # this is not ideal, better suggestions are welcome |
498 | eval '\\' . $sigil . $self->name . '::' . $name; |
499 | } |
500 | |
501 | sub remove_package_variable { |
502 | my ($self, $variable) = @_; |
503 | (defined $variable && $variable =~ /^[\$\@\%]/) |
504 | || confess "variable name does not have a sigil"; |
505 | my ($sigil, $name) = ($variable =~ /^(.)(.*)$/); |
506 | no strict 'refs'; |
507 | delete ${$self->name . '::'}{$name}; |
508 | } |
509 | |
8b978dd5 |
510 | 1; |
511 | |
512 | __END__ |
513 | |
514 | =pod |
515 | |
516 | =head1 NAME |
517 | |
518 | Class::MOP::Class - Class Meta Object |
519 | |
520 | =head1 SYNOPSIS |
521 | |
fe122940 |
522 | # use this for introspection ... |
523 | |
524 | package Foo; |
525 | sub meta { Class::MOP::Class->initialize(__PACKAGE__) } |
526 | |
527 | # elsewhere in the code ... |
528 | |
529 | # add a method to Foo ... |
530 | Foo->meta->add_method('bar' => sub { ... }) |
531 | |
532 | # get a list of all the classes searched |
533 | # the method dispatcher in the correct order |
534 | Foo->meta->class_precedence_list() |
535 | |
536 | # remove a method from Foo |
537 | Foo->meta->remove_method('bar'); |
538 | |
539 | # or use this to actually create classes ... |
540 | |
541 | Class::MOP::Class->create('Bar' => '0.01' => ( |
542 | superclasses => [ 'Foo' ], |
543 | attributes => [ |
544 | Class::MOP:::Attribute->new('$bar'), |
545 | Class::MOP:::Attribute->new('$baz'), |
546 | ], |
547 | methods => { |
548 | calculate_bar => sub { ... }, |
549 | construct_baz => sub { ... } |
550 | } |
551 | )); |
552 | |
8b978dd5 |
553 | =head1 DESCRIPTION |
554 | |
fe122940 |
555 | This is the largest and currently most complex part of the Perl 5 |
556 | meta-object protocol. It controls the introspection and |
557 | manipulation of Perl 5 classes (and it can create them too). The |
558 | best way to understand what this module can do, is to read the |
559 | documentation for each of it's methods. |
560 | |
552e3d24 |
561 | =head1 METHODS |
562 | |
2eb717d5 |
563 | =head2 Self Introspection |
564 | |
565 | =over 4 |
566 | |
567 | =item B<meta> |
568 | |
fe122940 |
569 | This will return a B<Class::MOP::Class> instance which is related |
570 | to this class. Thereby allowing B<Class::MOP::Class> to actually |
571 | introspect itself. |
572 | |
573 | As with B<Class::MOP::Attribute>, B<Class::MOP> will actually |
574 | bootstrap this module by installing a number of attribute meta-objects |
575 | into it's metaclass. This will allow this class to reap all the benifits |
576 | of the MOP when subclassing it. |
2eb717d5 |
577 | |
578 | =back |
579 | |
552e3d24 |
580 | =head2 Class construction |
581 | |
a2e85e6c |
582 | These methods will handle creating B<Class::MOP::Class> objects, |
583 | which can be used to both create new classes, and analyze |
584 | pre-existing classes. |
552e3d24 |
585 | |
586 | This module will internally store references to all the instances |
587 | you create with these methods, so that they do not need to be |
588 | created any more than nessecary. Basically, they are singletons. |
589 | |
590 | =over 4 |
591 | |
592 | =item B<create ($package_name, ?$package_version, |
a2e85e6c |
593 | superclasses =E<gt> ?@superclasses, |
594 | methods =E<gt> ?%methods, |
595 | attributes =E<gt> ?%attributes)> |
552e3d24 |
596 | |
a2e85e6c |
597 | This returns a B<Class::MOP::Class> object, bringing the specified |
552e3d24 |
598 | C<$package_name> into existence and adding any of the |
599 | C<$package_version>, C<@superclasses>, C<%methods> and C<%attributes> |
600 | to it. |
601 | |
602 | =item B<initialize ($package_name)> |
603 | |
a2e85e6c |
604 | This initializes and returns returns a B<Class::MOP::Class> object |
605 | for a given a C<$package_name>. |
606 | |
651955fb |
607 | =item B<construct_class_instance (%options)> |
a2e85e6c |
608 | |
609 | This will construct an instance of B<Class::MOP::Class>, it is |
610 | here so that we can actually "tie the knot" for B<Class::MOP::Class> |
611 | to use C<construct_instance> once all the bootstrapping is done. This |
612 | method is used internally by C<initialize> and should never be called |
613 | from outside of that method really. |
552e3d24 |
614 | |
615 | =back |
616 | |
c9e77dbb |
617 | =head2 Object instance construction and cloning |
a2e85e6c |
618 | |
c9e77dbb |
619 | These methods are B<entirely optional>, it is up to you whether you want |
620 | to use them or not. |
552e3d24 |
621 | |
622 | =over 4 |
623 | |
5f3c057a |
624 | =item B<new_object (%params)> |
625 | |
626 | This is a convience method for creating a new object of the class, and |
627 | blessing it into the appropriate package as well. Ideally your class |
628 | would call a C<new> this method like so: |
629 | |
630 | sub MyClass::new { |
631 | my ($class, %param) = @_; |
632 | $class->meta->new_object(%params); |
633 | } |
634 | |
635 | Of course the ideal place for this would actually be in C<UNIVERSAL::> |
636 | but that is considered bad style, so we do not do that. |
637 | |
cbd9f942 |
638 | =item B<construct_instance (%params)> |
552e3d24 |
639 | |
c9e77dbb |
640 | This method is used to construct an instace structure suitable for |
641 | C<bless>-ing into your package of choice. It works in conjunction |
642 | with the Attribute protocol to collect all applicable attributes. |
643 | |
cbd9f942 |
644 | This will construct and instance using a HASH ref as storage |
552e3d24 |
645 | (currently only HASH references are supported). This will collect all |
a2e85e6c |
646 | the applicable attributes and layout out the fields in the HASH ref, |
647 | it will then initialize them using either use the corresponding key |
648 | in C<%params> or any default value or initializer found in the |
649 | attribute meta-object. |
727919c5 |
650 | |
5f3c057a |
651 | =item B<clone_object ($instance, %params)> |
652 | |
653 | This is a convience method for cloning an object instance, then |
654 | blessing it into the appropriate package. Ideally your class |
655 | would call a C<clone> this method like so: |
656 | |
657 | sub MyClass::clone { |
658 | my ($self, %param) = @_; |
659 | $self->meta->clone_object($self, %params); |
660 | } |
661 | |
662 | Of course the ideal place for this would actually be in C<UNIVERSAL::> |
663 | but that is considered bad style, so we do not do that. |
664 | |
c9e77dbb |
665 | =item B<clone_instance($instance, %params)> |
666 | |
667 | This method is a compliment of C<construct_instance> (which means if |
668 | you override C<construct_instance>, you need to override this one too). |
669 | |
670 | This method will clone the C<$instance> structure created by the |
671 | C<construct_instance> method, and apply any C<%params> passed to it |
672 | to change the attribute values. The structure returned is (like with |
673 | C<construct_instance>) an unC<bless>ed HASH reference, it is your |
674 | responsibility to then bless this cloned structure into the right |
675 | class. |
676 | |
552e3d24 |
677 | =back |
678 | |
679 | =head2 Informational |
680 | |
681 | =over 4 |
682 | |
683 | =item B<name> |
684 | |
a2e85e6c |
685 | This is a read-only attribute which returns the package name for the |
686 | given B<Class::MOP::Class> instance. |
552e3d24 |
687 | |
688 | =item B<version> |
689 | |
690 | This is a read-only attribute which returns the C<$VERSION> of the |
a2e85e6c |
691 | package for the given B<Class::MOP::Class> instance. |
552e3d24 |
692 | |
693 | =back |
694 | |
695 | =head2 Inheritance Relationships |
696 | |
697 | =over 4 |
698 | |
699 | =item B<superclasses (?@superclasses)> |
700 | |
701 | This is a read-write attribute which represents the superclass |
a2e85e6c |
702 | relationships of the class the B<Class::MOP::Class> instance is |
703 | associated with. Basically, it can get and set the C<@ISA> for you. |
552e3d24 |
704 | |
343203ee |
705 | B<NOTE:> |
706 | Perl will occasionally perform some C<@ISA> and method caching, if |
707 | you decide to change your superclass relationship at runtime (which |
708 | is quite insane and very much not recommened), then you should be |
709 | aware of this and the fact that this module does not make any |
710 | attempt to address this issue. |
711 | |
552e3d24 |
712 | =item B<class_precedence_list> |
713 | |
a2e85e6c |
714 | This computes the a list of all the class's ancestors in the same order |
715 | in which method dispatch will be done. This is similair to |
716 | what B<Class::ISA::super_path> does, but we don't remove duplicate names. |
552e3d24 |
717 | |
718 | =back |
719 | |
720 | =head2 Methods |
721 | |
722 | =over 4 |
723 | |
2e41896e |
724 | =item B<method_metaclass> |
725 | |
552e3d24 |
726 | =item B<add_method ($method_name, $method)> |
727 | |
728 | This will take a C<$method_name> and CODE reference to that |
a2e85e6c |
729 | C<$method> and install it into the class's package. |
552e3d24 |
730 | |
a2e85e6c |
731 | B<NOTE>: |
732 | This does absolutely nothing special to C<$method> |
552e3d24 |
733 | other than use B<Sub::Name> to make sure it is tagged with the |
734 | correct name, and therefore show up correctly in stack traces and |
735 | such. |
736 | |
737 | =item B<has_method ($method_name)> |
738 | |
a2e85e6c |
739 | This just provides a simple way to check if the class implements |
552e3d24 |
740 | a specific C<$method_name>. It will I<not> however, attempt to check |
a2e85e6c |
741 | if the class inherits the method (use C<UNIVERSAL::can> for that). |
552e3d24 |
742 | |
743 | This will correctly handle functions defined outside of the package |
744 | that use a fully qualified name (C<sub Package::name { ... }>). |
745 | |
746 | This will correctly handle functions renamed with B<Sub::Name> and |
747 | installed using the symbol tables. However, if you are naming the |
748 | subroutine outside of the package scope, you must use the fully |
749 | qualified name, including the package name, for C<has_method> to |
750 | correctly identify it. |
751 | |
752 | This will attempt to correctly ignore functions imported from other |
753 | packages using B<Exporter>. It breaks down if the function imported |
754 | is an C<__ANON__> sub (such as with C<use constant>), which very well |
755 | may be a valid method being applied to the class. |
756 | |
757 | In short, this method cannot always be trusted to determine if the |
758 | C<$method_name> is actually a method. However, it will DWIM about |
a2e85e6c |
759 | 90% of the time, so it's a small trade off I think. |
552e3d24 |
760 | |
761 | =item B<get_method ($method_name)> |
762 | |
763 | This will return a CODE reference of the specified C<$method_name>, |
764 | or return undef if that method does not exist. |
765 | |
766 | =item B<remove_method ($method_name)> |
767 | |
a2e85e6c |
768 | This will attempt to remove a given C<$method_name> from the class. |
552e3d24 |
769 | It will return the CODE reference that it has removed, and will |
770 | attempt to use B<Sub::Name> to clear the methods associated name. |
771 | |
772 | =item B<get_method_list> |
773 | |
774 | This will return a list of method names for all I<locally> defined |
775 | methods. It does B<not> provide a list of all applicable methods, |
776 | including any inherited ones. If you want a list of all applicable |
777 | methods, use the C<compute_all_applicable_methods> method. |
778 | |
779 | =item B<compute_all_applicable_methods> |
780 | |
a2e85e6c |
781 | This will return a list of all the methods names this class will |
782 | respond to, taking into account inheritance. The list will be a list of |
552e3d24 |
783 | HASH references, each one containing the following information; method |
784 | name, the name of the class in which the method lives and a CODE |
785 | reference for the actual method. |
786 | |
787 | =item B<find_all_methods_by_name ($method_name)> |
788 | |
789 | This will traverse the inheritence hierarchy and locate all methods |
790 | with a given C<$method_name>. Similar to |
791 | C<compute_all_applicable_methods> it returns a list of HASH references |
792 | with the following information; method name (which will always be the |
793 | same as C<$method_name>), the name of the class in which the method |
794 | lives and a CODE reference for the actual method. |
795 | |
796 | The list of methods produced is a distinct list, meaning there are no |
797 | duplicates in it. This is especially useful for things like object |
798 | initialization and destruction where you only want the method called |
799 | once, and in the correct order. |
800 | |
801 | =back |
802 | |
803 | =head2 Attributes |
804 | |
805 | It should be noted that since there is no one consistent way to define |
806 | the attributes of a class in Perl 5. These methods can only work with |
807 | the information given, and can not easily discover information on |
a2e85e6c |
808 | their own. See L<Class::MOP::Attribute> for more details. |
552e3d24 |
809 | |
810 | =over 4 |
811 | |
2e41896e |
812 | =item B<attribute_metaclass> |
813 | |
7b31baf4 |
814 | =item B<get_attribute_map> |
815 | |
552e3d24 |
816 | =item B<add_attribute ($attribute_name, $attribute_meta_object)> |
817 | |
a2e85e6c |
818 | This stores a C<$attribute_meta_object> in the B<Class::MOP::Class> |
819 | instance associated with the given class, and associates it with |
820 | the C<$attribute_name>. Unlike methods, attributes within the MOP |
821 | are stored as meta-information only. They will be used later to |
822 | construct instances from (see C<construct_instance> above). |
552e3d24 |
823 | More details about the attribute meta-objects can be found in the |
a2e85e6c |
824 | L<Class::MOP::Attribute> or the L<Class::MOP/The Attribute protocol> |
825 | section. |
826 | |
827 | It should be noted that any accessor, reader/writer or predicate |
828 | methods which the C<$attribute_meta_object> has will be installed |
829 | into the class at this time. |
552e3d24 |
830 | |
831 | =item B<has_attribute ($attribute_name)> |
832 | |
a2e85e6c |
833 | Checks to see if this class has an attribute by the name of |
552e3d24 |
834 | C<$attribute_name> and returns a boolean. |
835 | |
836 | =item B<get_attribute ($attribute_name)> |
837 | |
838 | Returns the attribute meta-object associated with C<$attribute_name>, |
839 | if none is found, it will return undef. |
840 | |
841 | =item B<remove_attribute ($attribute_name)> |
842 | |
843 | This will remove the attribute meta-object stored at |
844 | C<$attribute_name>, then return the removed attribute meta-object. |
845 | |
a2e85e6c |
846 | B<NOTE:> |
847 | Removing an attribute will only affect future instances of |
552e3d24 |
848 | the class, it will not make any attempt to remove the attribute from |
849 | any existing instances of the class. |
850 | |
a2e85e6c |
851 | It should be noted that any accessor, reader/writer or predicate |
852 | methods which the attribute meta-object stored at C<$attribute_name> |
853 | has will be removed from the class at this time. This B<will> make |
854 | these attributes somewhat inaccessable in previously created |
855 | instances. But if you are crazy enough to do this at runtime, then |
856 | you are crazy enough to deal with something like this :). |
857 | |
552e3d24 |
858 | =item B<get_attribute_list> |
859 | |
860 | This returns a list of attribute names which are defined in the local |
861 | class. If you want a list of all applicable attributes for a class, |
862 | use the C<compute_all_applicable_attributes> method. |
863 | |
864 | =item B<compute_all_applicable_attributes> |
865 | |
c9e77dbb |
866 | This will traverse the inheritance heirachy and return a list of all |
867 | the applicable attributes for this class. It does not construct a |
868 | HASH reference like C<compute_all_applicable_methods> because all |
869 | that same information is discoverable through the attribute |
870 | meta-object itself. |
552e3d24 |
871 | |
872 | =back |
873 | |
52e8a34c |
874 | =head2 Package Variables |
875 | |
876 | Since Perl's classes are built atop the Perl package system, it is |
877 | fairly common to use package scoped variables for things like static |
878 | class variables. The following methods are convience methods for |
879 | the creation and inspection of package scoped variables. |
880 | |
881 | =over 4 |
882 | |
883 | =item B<add_package_variable ($variable_name, ?$initial_value)> |
884 | |
885 | Given a C<$variable_name>, which must contain a leading sigil, this |
886 | method will create that variable within the package which houses the |
887 | class. It also takes an optional C<$initial_value>, which must be a |
888 | reference of the same type as the sigil of the C<$variable_name> |
889 | implies. |
890 | |
891 | =item B<get_package_variable ($variable_name)> |
892 | |
893 | This will return a reference to the package variable in |
894 | C<$variable_name>. |
895 | |
896 | =item B<has_package_variable ($variable_name)> |
897 | |
898 | Returns true (C<1>) if there is a package variable defined for |
899 | C<$variable_name>, and false (C<0>) otherwise. |
900 | |
901 | =item B<remove_package_variable ($variable_name)> |
902 | |
903 | This will attempt to remove the package variable at C<$variable_name>. |
904 | |
905 | =back |
906 | |
8b978dd5 |
907 | =head1 AUTHOR |
908 | |
a2e85e6c |
909 | Stevan Little E<lt>stevan@iinteractive.comE<gt> |
8b978dd5 |
910 | |
911 | =head1 COPYRIGHT AND LICENSE |
912 | |
913 | Copyright 2006 by Infinity Interactive, Inc. |
914 | |
915 | L<http://www.iinteractive.com> |
916 | |
917 | This library is free software; you can redistribute it and/or modify |
918 | it under the same terms as Perl itself. |
919 | |
920 | =cut |