/interpreter/tags/at2dist091109/src/edu/vub/at/actors/natives/SharedActorField.java

 1/**
 2 * AmbientTalk/2 Project
 3 * SharedActorField.java created on Feb 25, 2007 at 9:02:22 AM
 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.natives;
29
30import edu.vub.at.exceptions.InterpreterException;
31import edu.vub.at.objects.ATObject;
32import edu.vub.at.objects.grammar.ATSymbol;
33
34/**
35 * SharedActorField is a class which is used to allow introducing additional fields into the
36 * lexical scope of every actor. They are passed at startup to the virtual machine and every
37 * actor will initialize them during the processing of its event_init. Note that actors should 
38 * never share objects, which is why this class does not store a value but rather has an abstract
39 * initialize method in which a new object can be created.  
40 *
41 * @author smostinc
42 */
43public abstract class SharedActorField {
44	
45	private final ATSymbol name_;
46	
47	public SharedActorField(ATSymbol name) {
48		name_ = name;
49	}
50	
51	public ATSymbol getName() {
52		return name_;
53	}
54	
55	/**
56	 * Hook to be overridden in order to initialize the field which should be installed in every
57	 * actor's lexical root object. The method is executed by the thread of the newly created 
58	 * actor, which can thus be accessed using ELActor.currentActor().
59	 * 
60	 * NOTE: if the return value is null, the field will not be added to the lexical root.
61	 * 
62	 * @return the object to be assigned to the field with the specified name in the current actor's lexical root
63	 */
64	public abstract ATObject initialize() throws InterpreterException; 
65
66}