/interpreter/tags/at2dist130208/src/edu/vub/at/actors/eventloops/FutureEvent.java

 1/**
 2 * AmbientTalk/2 Project
 3 * FutureEvent.java created on 27-dec-2006 at 15:50:33
 4 * (c) Programming Technology Lab, 2006 - 2007
 5 * Authors: Tom Van Cutsem & Stijn Mostinckx
 6 * 
 7 * Permission is hereby granted, free of charge, to any person
 8 * obtaining a copy of this software and associated documentation
 9 * files (the "Software"), to deal in the Software without
10 * restriction, including without limitation the rights to use,
11 * copy, modify, merge, publish, distribute, sublicense, and/or
12 * sell copies of the Software, and to permit persons to whom the
13 * Software is furnished to do so, subject to the following
14 * conditions:
15 *
16 * The above copyright notice and this permission notice shall be
17 * included in all copies or substantial portions of the Software.
18 *
19 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
20 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
21 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
22 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
23 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
24 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
25 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
26 * OTHER DEALINGS IN THE SOFTWARE.
27 */
28package edu.vub.at.actors.eventloops;
29
30/**
31 * A Future Event has an associated Future object to which the event
32 * will pass the return value or exception of a certain computation to be
33 * specified by a subclass.
34 *
35 * @author tvcutsem
36 */
37public abstract class FutureEvent extends Event {
38
39	private final Future future_;
40
41	/**
42	 * Verbode constructor which takes a future to be resolved by this event as well as a 
43	 * descriptive string describing this event for debugging purposes. 
44	 * @param description a description of the event for debugging purposes.
45	 * @param reply the future which will be resolved when this event has been executed.
46	 */
47	public FutureEvent(String description, Future reply) {
48		super(description);
49		future_ = reply;
50	}
51	
52	/**
53	 * Default constructor which takes a future to be resolved by this event. 
54	 * @param reply the future which will be resolved when this event has been executed.
55	 */
56	public FutureEvent(Future reply) {
57		future_ = reply;
58	}
59	
60	public void process(Object owner) {
61		try {
62			Object result = this.execute(owner);
63			future_.resolve(result);
64		} catch(Exception e) {
65			future_.ruin(e);
66		}
67	}
68	
69	/**
70	 * Template method to be overwritten by concrete instantiations of this class. This method
71	 * is called by the {@link FutureEvent#process(Object)} method and its outcome is used to
72	 * resolve or ruin the Future attached to this event.
73	 */
74	public abstract Object execute(Object owner) throws Exception;
75
76}