1 /*
2 * Entreri, an entity-component framework in Java
3 *
4 * Copyright (c) 2013, Michael Ludwig
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without modification,
8 * are permitted provided that the following conditions are met:
9 *
10 * Redistributions of source code must retain the above copyright notice,
11 * this list of conditions and the following disclaimer.
12 * Redistributions in binary form must reproduce the above copyright notice,
13 * this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
18 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
19 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
20 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
21 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
22 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
23 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
25 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 */
27 package com.lhkbob.entreri;
28
29 import java.lang.annotation.*;
30
31 /**
32 * <p/>
33 * The Requires annotation can be used to specify dependencies within a package of
34 * components. If one component requires the use of another, such as a scene or light
35 * component needing a transform, this can be a convenient way to specify this
36 * relationship and reduce the amount of explicit configuration during entity
37 * initialization.
38 * <p/>
39 * If a component type extends an additional abstract component type that also is
40 * annotated with Requires, the union of the required types is the effective set of
41 * types.
42 * <p/>
43 * When a component type that has been annotated with this annotation is added to an
44 * entity, all required component types that are not already attached to the entity are
45 * added. All newly added components have their owner set to the initial component so that
46 * when it's removed, the required components are cleaned up as well.
47 *
48 * @author Michael Ludwig
49 */
50 @Documented
51 @Target(ElementType.TYPE)
52 @Retention(RetentionPolicy.RUNTIME)
53 public @interface Requires {
54 /**
55 * @return All Component types required by the annotated component type
56 */
57 Class<? extends Component>[] value();
58 }