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Java > Open Source Codes > org > apache > commons > betwixt > expression > Expression


1 /*
2  * Copyright 2001-2004 The Apache Software Foundation.
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  * http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 package org.apache.commons.betwixt.expression;
17
18 /** <p><code>Expression</code> represents an arbitrary expression on a bean.</p>
19   *
20   * @author <a HREF="mailto:jstrachan@apache.org">James Strachan</a>
21   */
22 public interface Expression {
23
24     /** Evaluates the expression on the bean with the given context
25      * and returns the result
26      *
27      * @param context evaluate against this <code>Context</code>
28      * @return the value of the expression
29      */
30     public Object JavaDoc evaluate(Context context);
31     
32     
33     /* XXX
34        Is update actually useful?
35        None of the expression implementations i can find do anything when it's called.
36        I suspect that it's been replaced by Updater
37        but i maybe i'm missing something subtle
38     */
39     /** <p>Updates the current bean context with a new String value.
40      * This is typically used when parsing XML and updating a beans value
41      * from XML.<p>
42      *
43      * @param context update this <code>Context</code>
44      * @param newValue the new value for this expression
45      * @deprecated 0.5 use {@link Updater} instead
46      */
47     public void update(Context context, String JavaDoc newValue);
48 }
49
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