2 package Class::MOP::Instance;
7 use Scalar::Util 'weaken', 'blessed';
12 require Class::MOP::Class;
13 Class::MOP::Class->initialize(blessed($_[0]) || $_[0]);
17 my ($class, $meta, @attrs) = @_;
18 my @slots = map { $_->slots } @attrs;
21 # I am not sure that it makes
22 # sense to pass in the meta
23 # The ideal would be to just
24 # pass in the class name, but
25 # that is placing too much of
26 # an assumption on bless(),
27 # which is *probably* a safe
28 # assumption,.. but you can
31 slots => { map { $_ => undef } @slots },
37 $self->bless_instance_structure({});
40 sub bless_instance_structure {
41 my ($self, $instance_structure) = @_;
42 bless $instance_structure, $self->{meta}->name;
46 my ($self, $instance) = @_;
47 $self->bless_instance_structure({ %$instance });
50 # operations on meta instance
54 return keys %{$self->{slots}};
58 my ($self, $slot_name) = @_;
59 exists $self->{slots}->{$slot_name} ? 1 : 0;
62 # operations on created instances
65 my ($self, $instance, $slot_name) = @_;
66 return $instance->{$slot_name};
70 my ($self, $instance, $slot_name, $value) = @_;
71 $instance->{$slot_name} = $value;
75 my ($self, $instance, $slot_name) = @_;
76 $self->set_slot_value($instance, $slot_name, undef);
79 sub initialize_all_slots {
80 my ($self, $instance) = @_;
81 foreach my $slot_name ($self->get_all_slots) {
82 $self->initialize_slot($instance, $slot_name);
86 sub is_slot_initialized {
87 my ($self, $instance, $slot_name, $value) = @_;
88 exists $instance->{$slot_name} ? 1 : 0;
91 sub weaken_slot_value {
92 my ($self, $instance, $slot_name) = @_;
93 weaken $instance->{$slot_name};
96 sub strengthen_slot_value {
97 my ($self, $instance, $slot_name) = @_;
98 $self->set_slot_value($instance, $slot_name, $self->get_slot_value($instance, $slot_name));
101 # inlinable operation snippets
103 sub inline_slot_access {
104 my ($self, $instance, $slot_name) = @_;
105 sprintf "%s->{%s}", $instance, $slot_name;
108 sub inline_get_slot_value {
109 my ($self, $instance, $slot_name) = @_;
110 $self->inline_slot_access($instance, $slot_name);
113 sub inline_set_slot_value {
114 my ($self, $instance, $slot_name, $value) = @_;
115 $self->inline_slot_access($instance, $slot_name) . " = $value",
118 sub inline_initialize_slot {
119 my ($self, $instance, $slot_name) = @_;
120 $self->inline_set_slot_value($instance, $slot_name, 'undef'),
123 sub inline_is_slot_initialized {
124 my ($self, $instance, $slot_name) = @_;
125 "exists " . $self->inline_slot_access($instance, $slot_name) . " ? 1 : 0";
128 sub inline_weaken_slot_value {
129 my ($self, $instance, $slot_name) = @_;
130 sprintf "Scalar::Util::weaken( %s )", $self->inline_slot_access($instance, $slot_name);
133 sub inline_strengthen_slot_value {
134 my ($self, $instance, $slot_name) = @_;
135 $self->inline_set_slot_value($instance, $slot_name, $self->inline_slot_access($instance, $slot_name));
146 Class::MOP::Instance - Instance Meta Object
150 # for the most part, this protocol is internal
151 # and not for public usage, but this how one
159 ':instance_metaclass' => 'ArrayBasedStorage::Instance',
162 # now Foo->new produces blessed ARRAY ref based objects
166 This is a sub-protocol which governs instance creation
167 and access to the slots of the instance structure.
169 This may seem like over-abstraction, but by abstracting
170 this process into a sub-protocol we make it possible to
171 easily switch the details of how an object's instance is
172 stored with minimal impact. In most cases just subclassing
173 this class will be all you need to do (see the examples;
174 F<examples/ArrayBasedStorage.pod> and
175 F<examples/InsideOutClass.pod> for details).
181 =item B<new ($meta, @attrs)>
183 Creates a new instance meta-object and gathers all the slots from
184 the list of C<@attrs> given.
188 This will return a B<Class::MOP::Class> instance which is related
193 =head2 Creation of Instances
197 =item B<create_instance>
199 This creates the appropriate structure needed for the instance and
200 then calls C<bless_instance_structure> to bless it into the class.
202 =item B<bless_instance_structure ($instance_structure)>
204 This does just exactly what it says it does.
206 =item B<clone_instance ($instance_structure)>
210 =head2 Instrospection
212 NOTE: There might be more methods added to this part of the API,
213 we will add then when we need them basically.
217 =item B<get_all_slots>
219 This will return the current list of slots based on what was
220 given to this object in C<new>.
222 =item B<is_valid_slot ($slot_name)>
226 =head2 Operations on Instance Structures
228 An important distinction of this sub-protocol is that the
229 instance meta-object is a different entity from the actual
230 instance it creates. For this reason, any actions on slots
231 require that the C<$instance_structure> is passed into them.
235 =item B<get_slot_value ($instance_structure, $slot_name)>
237 =item B<set_slot_value ($instance_structure, $slot_name, $value)>
239 =item B<initialize_slot ($instance_structure, $slot_name)>
241 =item B<initialize_all_slots ($instance_structure)>
243 =item B<is_slot_initialized ($instance_structure, $slot_name)>
245 =item B<weaken_slot_value ($instance_structure, $slot_name)>
247 =item B<strengthen_slot_value ($instance_structure, $slot_name)>
251 =head2 Inlineable Instance Operations
253 This part of the API is currently un-used. It is there for use
254 in future experiments in class finailization mostly. Best to
259 =item B<inline_slot_access ($instance_structure, $slot_name)>
261 =item B<inline_get_slot_value ($instance_structure, $slot_name)>
263 =item B<inline_set_slot_value ($instance_structure, $slot_name, $value)>
265 =item B<inline_initialize_slot ($instance_structure, $slot_name)>
267 =item B<inline_is_slot_initialized ($instance_structure, $slot_name)>
269 =item B<inline_weaken_slot_value ($instance_structure, $slot_name)>
271 =item B<inline_strengthen_slot_value ($instance_structure, $slot_name)>
277 Yuval Kogman E<lt>nothingmuch@woobling.comE<gt>
279 Stevan Little E<lt>stevan@iinteractive.comE<gt>
281 =head1 COPYRIGHT AND LICENSE
283 Copyright 2006 by Infinity Interactive, Inc.
285 L<http://www.iinteractive.com>
287 This library is free software; you can redistribute it and/or modify
288 it under the same terms as Perl itself.