2 package Class::MOP::Instance;
7 use Scalar::Util 'weaken', 'blessed';
10 our $AUTHORITY = 'cpan:STEVAN';
13 require Class::MOP::Class;
14 Class::MOP::Class->initialize(blessed($_[0]) || $_[0]);
18 my ($class, $meta, @attrs) = @_;
19 my @slots = map { $_->slots } @attrs;
20 my $instance = bless {
22 # I am not sure that it makes
23 # sense to pass in the meta
24 # The ideal would be to just
25 # pass in the class name, but
26 # that is placing too much of
27 # an assumption on bless(),
28 # which is *probably* a safe
29 # assumption,.. but you can
32 '@!slots' => { map { $_ => undef } @slots },
35 weaken($instance->{'$!meta'});
40 sub associated_metaclass { (shift)->{'$!meta'} }
44 $self->bless_instance_structure({});
47 sub bless_instance_structure {
48 my ($self, $instance_structure) = @_;
49 bless $instance_structure, $self->associated_metaclass->name;
53 my ($self, $instance) = @_;
54 $self->bless_instance_structure({ %$instance });
57 # operations on meta instance
61 return keys %{$self->{'@!slots'}};
65 my ($self, $slot_name) = @_;
66 exists $self->{'@!slots'}->{$slot_name} ? 1 : 0;
69 # operations on created instances
72 my ($self, $instance, $slot_name) = @_;
73 return $instance->{$slot_name};
77 my ($self, $instance, $slot_name, $value) = @_;
78 $instance->{$slot_name} = $value;
82 my ($self, $instance, $slot_name) = @_;
83 $self->set_slot_value($instance, $slot_name, undef);
86 sub deinitialize_slot {
87 my ( $self, $instance, $slot_name ) = @_;
88 delete $instance->{$slot_name};
91 sub initialize_all_slots {
92 my ($self, $instance) = @_;
93 foreach my $slot_name ($self->get_all_slots) {
94 $self->initialize_slot($instance, $slot_name);
98 sub deinitialize_all_slots {
99 my ($self, $instance) = @_;
100 foreach my $slot_name ($self->get_all_slots) {
101 $self->deinitialize_slot($instance, $slot_name);
105 sub is_slot_initialized {
106 my ($self, $instance, $slot_name, $value) = @_;
107 exists $instance->{$slot_name} ? 1 : 0;
110 sub weaken_slot_value {
111 my ($self, $instance, $slot_name) = @_;
112 weaken $instance->{$slot_name};
115 sub strengthen_slot_value {
116 my ($self, $instance, $slot_name) = @_;
117 $self->set_slot_value($instance, $slot_name, $self->get_slot_value($instance, $slot_name));
120 # inlinable operation snippets
122 sub is_inlinable { 1 }
124 sub inline_create_instance {
125 my ($self, $class_variable) = @_;
126 'bless {} => ' . $class_variable;
129 sub inline_slot_access {
130 my ($self, $instance, $slot_name) = @_;
131 sprintf "%s->{%s}", $instance, $slot_name;
134 sub inline_get_slot_value {
135 my ($self, $instance, $slot_name) = @_;
136 $self->inline_slot_access($instance, $slot_name);
139 sub inline_set_slot_value {
140 my ($self, $instance, $slot_name, $value) = @_;
141 $self->inline_slot_access($instance, $slot_name) . " = $value",
144 sub inline_initialize_slot {
145 my ($self, $instance, $slot_name) = @_;
146 $self->inline_set_slot_value($instance, $slot_name, 'undef'),
149 sub inline_deinitialize_slot {
150 my ($self, $instance, $slot_name) = @_;
151 "delete " . $self->inline_slot_access($instance, $slot_name);
153 sub inline_is_slot_initialized {
154 my ($self, $instance, $slot_name) = @_;
155 "exists " . $self->inline_slot_access($instance, $slot_name) . " ? 1 : 0";
158 sub inline_weaken_slot_value {
159 my ($self, $instance, $slot_name) = @_;
160 sprintf "Scalar::Util::weaken( %s )", $self->inline_slot_access($instance, $slot_name);
163 sub inline_strengthen_slot_value {
164 my ($self, $instance, $slot_name) = @_;
165 $self->inline_set_slot_value($instance, $slot_name, $self->inline_slot_access($instance, $slot_name));
176 Class::MOP::Instance - Instance Meta Object
180 # for the most part, this protocol is internal
181 # and not for public usage, but this how one
189 ':instance_metaclass' => 'ArrayBasedStorage::Instance',
192 # now Foo->new produces blessed ARRAY ref based objects
196 This is a sub-protocol which governs instance creation
197 and access to the slots of the instance structure.
199 This may seem like over-abstraction, but by abstracting
200 this process into a sub-protocol we make it possible to
201 easily switch the details of how an object's instance is
202 stored with minimal impact. In most cases just subclassing
203 this class will be all you need to do (see the examples;
204 F<examples/ArrayBasedStorage.pod> and
205 F<examples/InsideOutClass.pod> for details).
211 =item B<new ($meta, @attrs)>
213 Creates a new instance meta-object and gathers all the slots from
214 the list of C<@attrs> given.
218 This will return a B<Class::MOP::Class> instance which is related
223 =head2 Creation of Instances
227 =item B<create_instance>
229 This creates the appropriate structure needed for the instance and
230 then calls C<bless_instance_structure> to bless it into the class.
232 =item B<bless_instance_structure ($instance_structure)>
234 This does just exactly what it says it does.
236 =item B<clone_instance ($instance_structure)>
240 =head2 Instrospection
242 NOTE: There might be more methods added to this part of the API,
243 we will add then when we need them basically.
247 =item B<associated_metaclass>
249 =item B<get_all_slots>
251 This will return the current list of slots based on what was
252 given to this object in C<new>.
254 =item B<is_valid_slot ($slot_name)>
258 =head2 Operations on Instance Structures
260 An important distinction of this sub-protocol is that the
261 instance meta-object is a different entity from the actual
262 instance it creates. For this reason, any actions on slots
263 require that the C<$instance_structure> is passed into them.
267 =item B<get_slot_value ($instance_structure, $slot_name)>
269 =item B<set_slot_value ($instance_structure, $slot_name, $value)>
271 =item B<initialize_slot ($instance_structure, $slot_name)>
273 =item B<deinitialize_slot ($instance_structure, $slot_name)>
275 =item B<initialize_all_slots ($instance_structure)>
277 =item B<deinitialize_all_slots ($instance_structure)>
279 =item B<is_slot_initialized ($instance_structure, $slot_name)>
281 =item B<weaken_slot_value ($instance_structure, $slot_name)>
283 =item B<strengthen_slot_value ($instance_structure, $slot_name)>
287 =head2 Inlineable Instance Operations
289 This part of the API is currently un-used. It is there for use
290 in future experiments in class finailization mostly. Best to
295 =item B<is_inlinable>
297 Each meta-instance should override this method to tell Class::MOP if it's
298 possible to inline the slot access.
300 This is currently only used by Class::MOP::Class::Immutable when performing
303 =item B<inline_create_instance>
305 =item B<inline_slot_access ($instance_structure, $slot_name)>
307 =item B<inline_get_slot_value ($instance_structure, $slot_name)>
309 =item B<inline_set_slot_value ($instance_structure, $slot_name, $value)>
311 =item B<inline_initialize_slot ($instance_structure, $slot_name)>
313 =item B<inline_deinitialize_slot ($instance_structure, $slot_name)>
315 =item B<inline_is_slot_initialized ($instance_structure, $slot_name)>
317 =item B<inline_weaken_slot_value ($instance_structure, $slot_name)>
319 =item B<inline_strengthen_slot_value ($instance_structure, $slot_name)>
325 Yuval Kogman E<lt>nothingmuch@woobling.comE<gt>
327 Stevan Little E<lt>stevan@iinteractive.comE<gt>
329 =head1 COPYRIGHT AND LICENSE
331 Copyright 2006, 2007 by Infinity Interactive, Inc.
333 L<http://www.iinteractive.com>
335 This library is free software; you can redistribute it and/or modify
336 it under the same terms as Perl itself.