/interpreter/tags/at2-build270707/src/edu/vub/at/objects/ATField.java

 1/**
 2 * AmbientTalk/2 Project
 3 * ATField.java created on Jul 23, 2006 at 11:52:56 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.objects;
29
30import edu.vub.at.exceptions.InterpreterException;
31import edu.vub.at.objects.grammar.ATSymbol;
32
33/**
34 * ATField provides a mapping from an immutable name to a potentially mutable value.
35 * <p>
36 * Note that when field objects are added to an {@link ATObject} and then that object is cloned,
37 * the field object will be re-instantiated (i.e. its 'new' method is invoked).
38 * This implies that any object implementing ATField should provide a meta_newInstance
39 * method whose sole initarg is the new host for the field.
40 * 
41 * @author smostinc
42 */
43public interface ATField extends ATObject {
44	
45	/**
46	 * Returns a string by which the slot can be identified.
47	 * 
48	 * @return a {@link ATSymbol} representing the string by which the slot can be identified.
49	 */
50	public ATSymbol base_name() throws InterpreterException;
51	
52	/**
53	 * Returns the current value of the field.
54	 * 
55	 * @return an {@link ATObject} representing the current value of the field.
56	 * @throws XIllegalOperation if the field accessed is not found.
57	 */
58	public ATObject base_readField() throws InterpreterException;
59	
60	/**
61	 * Sets the value of the field if possible.
62	 * 
63	 * @param newValue the value the field should hold.
64	 * @return by default, the new value
65	 * @throws InterpreterException if the field cannot be modified.
66	 */
67	public ATObject base_writeField(ATObject newValue) throws InterpreterException;
68
69}