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comparison dwtx/core/commands/AbstractHandler.d @ 3:6518c18a01f7

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eclipse.core package without osgi dependencies
author Frank Benoit <benoit@tionex.de>
date Wed, 26 Mar 2008 00:57:19 +0100
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2:a012107a911c 3:6518c18a01f7
1 /*******************************************************************************
2 * Copyright (c) 2004, 2006 IBM Corporation and others.
3 * All rights reserved. This program and the accompanying materials
4 * are made available under the terms of the Eclipse Public License v1.0
5 * which accompanies this distribution, and is available at
6 * http://www.eclipse.org/legal/epl-v10.html
7 *
8 * Contributors:
9 * IBM Corporation - initial API and implementation
10 * Port to the D programming language:
11 * Frank Benoit <benoit@tionex.de>
12 *******************************************************************************/
13 module dwtx.core.commands.AbstractHandler;
14
15 import dwtx.core.commands.common.EventManager;
16 import dwtx.core.commands.IHandler;
17 import dwtx.core.commands.IHandlerListener;
18 import dwtx.core.commands.HandlerEvent;
19
20 import dwt.dwthelper.utils;
21
22 /**
23 * <p>
24 * This class is a partial implementation of <code>IHandler</code>. This
25 * abstract implementation provides support for handler listeners. You should
26 * subclass from this method unless you want to implement your own listener
27 * support. Subclasses should call
28 * {@link AbstractHandler#fireHandlerChanged(HandlerEvent)}when the handler
29 * changes. Subclasses can also override {@link AbstractHandler#isEnabled()} and
30 * {@link AbstractHandler#isHandled()}.
31 * </p>
32 *
33 * @since 3.1
34 */
35 public abstract class AbstractHandler : EventManager, IHandler {
36
37 /**
38 * @see IHandler#addHandlerListener(IHandlerListener)
39 */
40 public void addHandlerListener(IHandlerListener handlerListener) {
41 addListenerObject(cast(Object)handlerListener);
42 }
43
44 /**
45 * The default implementation does nothing. Subclasses who attach listeners
46 * to other objects are encouraged to detach them in this method.
47 *
48 * @see dwtx.core.commands.IHandler#dispose()
49 */
50 public void dispose() {
51 // Do nothing.
52 }
53
54 /**
55 * Fires an event to all registered listeners describing changes to this
56 * instance.
57 * <p>
58 * Subclasses may extend the definition of this method (i.e., if a different
59 * type of listener can be attached to a subclass). This is used primarily
60 * for support of <code>AbstractHandler</code> in
61 * <code>dwtx.ui.workbench</code>, and clients should be wary of
62 * overriding this behaviour. If this method is overridden, then the first
63 * line of the method should be "<code>super.fireHandlerChanged(handlerEvent);</code>".
64 * </p>
65 *
66 * @param handlerEvent
67 * the event describing changes to this instance. Must not be
68 * <code>null</code>.
69 */
70 protected void fireHandlerChanged(HandlerEvent handlerEvent) {
71 if (handlerEvent is null) {
72 throw new NullPointerException();
73 }
74
75 Object[] listeners = getListeners();
76 for (int i = 0; i < listeners.length; i++) {
77 IHandlerListener listener = cast(IHandlerListener) listeners[i];
78 listener.handlerChanged(handlerEvent);
79 }
80 }
81
82 /**
83 * Whether this handler is capable of executing at this time. Subclasses may
84 * override this method.
85 *
86 * @return <code>true</code>
87 */
88 public bool isEnabled() {
89 return true;
90 }
91
92 /**
93 * Whether this handler is capable of handling delegated responsibilities at
94 * this time. Subclasses may override this method.
95 *
96 * @return <code>true</code>
97 */
98 public bool isHandled() {
99 return true;
100 }
101
102 /**
103 * <p>
104 * Returns true iff there is one or more IHandlerListeners attached to this
105 * AbstractHandler.
106 * </p>
107 * <p>
108 * Subclasses may extend the definition of this method (i.e., if a different
109 * type of listener can be attached to a subclass). This is used primarily
110 * for support of <code>AbstractHandler</code> in
111 * <code>dwtx.ui.workbench</code>, and clients should be wary of
112 * overriding this behaviour. If this method is overridden, then the return
113 * value should include "<code>super.hasListeners() ||</code>".
114 * </p>
115 *
116 * @return true iff there is one or more IHandlerListeners attached to this
117 * AbstractHandler
118 */
119 protected bool hasListeners() {
120 return isListenerAttached();
121 }
122
123 /**
124 * @see IHandler#removeHandlerListener(IHandlerListener)
125 */
126 public void removeHandlerListener(IHandlerListener handlerListener) {
127 removeListenerObject(cast(Object)handlerListener);
128 }
129 }