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1 | |
2 | package Class::MOP::Instance; |
3 | |
4 | use strict; |
5 | use warnings; |
6 | |
9fa4d0b4 |
7 | use Scalar::Util 'weaken'; |
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8 | |
9 | our $VERSION = '0.01'; |
10 | |
11 | sub meta { |
12 | require Class::MOP::Class; |
13 | Class::MOP::Class->initialize(blessed($_[0]) || $_[0]); |
14 | } |
15 | |
16 | sub new { |
052c2a1a |
17 | my ($class, $meta, @attrs) = @_; |
c57c8b10 |
18 | my @slots = map { $_->slots } @attrs; |
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19 | bless { |
fc3ddd1d |
20 | # NOTE: |
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 |
29 | # never tell <:) |
49c93440 |
30 | meta => $meta, |
f7259199 |
31 | slots => { map { $_ => undef } @slots }, |
24869f62 |
32 | } => $class; |
33 | } |
34 | |
49c93440 |
35 | sub create_instance { |
36 | my $self = shift; |
37 | $self->bless_instance_structure({}); |
2d711cc8 |
38 | } |
39 | |
49c93440 |
40 | sub bless_instance_structure { |
41 | my ($self, $instance_structure) = @_; |
42 | bless $instance_structure, $self->{meta}->name; |
2d711cc8 |
43 | } |
44 | |
f7259199 |
45 | sub clone_instance { |
46 | my ($self, $instance) = @_; |
47 | $self->bless_instance_structure({ %$instance }); |
48 | } |
49 | |
2d711cc8 |
50 | # operations on meta instance |
51 | |
eb49acde |
52 | sub get_all_slots { |
53 | my $self = shift; |
f7259199 |
54 | return keys %{$self->{slots}}; |
55 | } |
56 | |
57 | sub is_valid_slot { |
58 | my ($self, $slot_name) = @_; |
59 | exists $self->{slots}->{$slot_name} ? 1 : 0; |
839ea973 |
60 | } |
61 | |
2d711cc8 |
62 | # operations on created instances |
63 | |
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64 | sub get_slot_value { |
2bab2be6 |
65 | my ($self, $instance, $slot_name) = @_; |
66 | return $instance->{$slot_name}; |
839ea973 |
67 | } |
68 | |
2bab2be6 |
69 | sub set_slot_value { |
70 | my ($self, $instance, $slot_name, $value) = @_; |
71 | $instance->{$slot_name} = $value; |
72 | } |
73 | |
2d711cc8 |
74 | sub initialize_slot { |
49c93440 |
75 | my ($self, $instance, $slot_name) = @_; |
76 | $instance->{$slot_name} = undef; |
2d711cc8 |
77 | } |
78 | |
c174112e |
79 | sub initialize_all_slots { |
80 | my ($self, $instance) = @_; |
81 | foreach my $slot_name ($self->get_all_slots) { |
82 | $self->initialize_slot($instance, $slot_name); |
83 | } |
84 | } |
85 | |
49c93440 |
86 | sub is_slot_initialized { |
87 | my ($self, $instance, $slot_name, $value) = @_; |
2d711cc8 |
88 | exists $instance->{$slot_name} ? 1 : 0; |
2bab2be6 |
89 | } |
839ea973 |
90 | |
5582521c |
91 | sub weaken_slot_value { |
92 | my ($self, $instance, $slot_name) = @_; |
93 | weaken $instance->{$slot_name}; |
94 | } |
95 | |
96 | sub strengthen_slot_value { |
97 | my ($self, $instance, $slot_name) = @_; |
98 | $self->set_slot_value($instance, $slot_name, $self->get_slot_value($instance, $slot_name)); |
99 | } |
100 | |
ee7c0467 |
101 | # inlinable operation snippets |
102 | |
103 | sub inline_slot_access { |
104 | my ($self, $instance, $slot_name) = @_; |
105 | sprintf "%s->{%s}", $instance, $slot_name; |
106 | } |
107 | |
108 | sub inline_get_slot_value { |
109 | my ($self, $instance, $slot_name) = @_; |
110 | $self->inline_slot_access($instance, $slot_name); |
111 | } |
112 | |
113 | sub inline_set_slot_value { |
114 | my ($self, $instance, $slot_name, $value) = @_; |
115 | $self->inline_slot_access($instance, $slot_name) . " = $value", |
116 | } |
117 | |
118 | sub inline_initialize_slot { |
119 | my ($self, $instance, $slot_name) = @_; |
120 | $self->inline_set_slot_value($instance, $slot_name, 'undef'), |
121 | } |
122 | |
123 | sub inline_is_slot_initialized { |
124 | my ($self, $instance, $slot_name) = @_; |
125 | "exists " . $self->inline_slot_access($instance, $slot_name) . " ? 1 : 0"; |
126 | } |
127 | |
128 | sub inline_weaken_slot_value { |
129 | my ($self, $instance, $slot_name) = @_; |
130 | sprintf "Scalar::Util::weaken( %s )", $self->inline_slot_access($instance, $slot_name); |
131 | } |
132 | |
133 | sub inline_strengthen_slot_value { |
134 | my ($self, $instance, $slot_name) = @_; |
135 | $self->inline_set_slot_value($instance, $slot_name, $self->inline_slot_access($instance, $slot_name)); |
136 | } |
137 | |
24869f62 |
138 | 1; |
139 | |
140 | __END__ |
141 | |
142 | =pod |
143 | |
144 | =head1 NAME |
145 | |
146 | Class::MOP::Instance - Instance Meta Object |
147 | |
148 | =head1 SYNOPSIS |
149 | |
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150 | # for the most part, this protocol is internal |
151 | # and not for public usage, but this how one |
152 | # might use it |
153 | |
154 | package Foo; |
155 | |
156 | use strict; |
157 | use warnings; |
1becdfcc |
158 | use metaclass ( |
9fa4d0b4 |
159 | ':instance_metaclass' => 'ArrayBasedStorage::Instance', |
160 | ); |
161 | |
162 | # now Foo->new produces blessed ARRAY ref based objects |
163 | |
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164 | =head1 DESCRIPTION |
165 | |
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166 | This is a sub-protocol which governs instance creation |
167 | and access to the slots of the instance structure. |
168 | |
169 | This may seem like over-abstraction, but by abstracting |
170 | this process into a sub-protocol we make it possible to |
171 | easily switch the details of how an object's instance is |
172 | stored with minimal impact. In most cases just subclassing |
1becdfcc |
173 | this class will be all you need to do (see the examples; |
174 | F<examples/ArrayBasedStorage.pod> and |
175 | F<examples/InsideOutClass.pod> for details). |
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176 | |
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177 | =head1 METHODS |
178 | |
179 | =over 4 |
180 | |
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181 | =item B<new ($meta, @attrs)> |
182 | |
183 | Creates a new instance meta-object and gathers all the slots from |
184 | the list of C<@attrs> given. |
185 | |
186 | =item B<meta> |
187 | |
188 | This will return a B<Class::MOP::Class> instance which is related |
189 | to this class. |
190 | |
191 | =back |
192 | |
193 | =head2 Creation of Instances |
194 | |
195 | =over 4 |
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196 | |
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197 | =item B<create_instance> |
198 | |
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199 | This creates the appropriate structure needed for the instance and |
200 | then calls C<bless_instance_structure> to bless it into the class. |
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201 | |
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202 | =item B<bless_instance_structure ($instance_structure)> |
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203 | |
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204 | This does just exactly what it says it does. |
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205 | |
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206 | =item B<clone_instance ($instance_structure)> |
207 | |
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208 | =back |
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209 | |
9fa4d0b4 |
210 | =head2 Instrospection |
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211 | |
9fa4d0b4 |
212 | NOTE: There might be more methods added to this part of the API, |
213 | we will add then when we need them basically. |
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214 | |
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215 | =over 4 |
216 | |
217 | =item B<get_all_slots> |
218 | |
219 | This will return the current list of slots based on what was |
220 | given to this object in C<new>. |
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221 | |
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222 | =item B<is_valid_slot ($slot_name)> |
223 | |
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224 | =back |
225 | |
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226 | =head2 Operations on Instance Structures |
227 | |
228 | An important distinction of this sub-protocol is that the |
229 | instance meta-object is a different entity from the actual |
230 | instance it creates. For this reason, any actions on slots |
231 | require that the C<$instance_structure> is passed into them. |
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232 | |
233 | =over 4 |
234 | |
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235 | =item B<get_slot_value ($instance_structure, $slot_name)> |
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236 | |
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237 | =item B<set_slot_value ($instance_structure, $slot_name, $value)> |
238 | |
239 | =item B<initialize_slot ($instance_structure, $slot_name)> |
240 | |
241 | =item B<initialize_all_slots ($instance_structure)> |
242 | |
243 | =item B<is_slot_initialized ($instance_structure, $slot_name)> |
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244 | |
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245 | =item B<weaken_slot_value ($instance_structure, $slot_name)> |
246 | |
247 | =item B<strengthen_slot_value ($instance_structure, $slot_name)> |
248 | |
249 | =back |
250 | |
251 | =head2 Inlineable Instance Operations |
252 | |
f7259199 |
253 | This part of the API is currently un-used. It is there for use |
254 | in future experiments in class finailization mostly. Best to |
255 | ignore this for now. |
256 | |
ee7c0467 |
257 | =over 4 |
258 | |
259 | =item B<inline_slot_access ($instance_structure, $slot_name)> |
260 | |
261 | =item B<inline_get_slot_value ($instance_structure, $slot_name)> |
262 | |
263 | =item B<inline_set_slot_value ($instance_structure, $slot_name, $value)> |
264 | |
265 | =item B<inline_initialize_slot ($instance_structure, $slot_name)> |
266 | |
267 | =item B<inline_is_slot_initialized ($instance_structure, $slot_name)> |
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268 | |
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269 | =item B<inline_weaken_slot_value ($instance_structure, $slot_name)> |
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270 | |
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271 | =item B<inline_strengthen_slot_value ($instance_structure, $slot_name)> |
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272 | |
24869f62 |
273 | =back |
274 | |
275 | =head1 AUTHOR |
276 | |
9fa4d0b4 |
277 | Yuval Kogman E<lt>nothingmuch@woobling.comE<gt> |
278 | |
24869f62 |
279 | Stevan Little E<lt>stevan@iinteractive.comE<gt> |
280 | |
281 | =head1 COPYRIGHT AND LICENSE |
282 | |
283 | Copyright 2006 by Infinity Interactive, Inc. |
284 | |
285 | L<http://www.iinteractive.com> |
286 | |
287 | This library is free software; you can redistribute it and/or modify |
288 | it under the same terms as Perl itself. |
289 | |
84ef30d1 |
290 | =cut |
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291 | |