OverrideableCommand


1   /**
2    * <copyright> 
3    *
4    * Copyright (c) 2002-2004 IBM Corporation and others.
5    * All rights reserved.   This program and the accompanying materials
6    * are made available under the terms of the Eclipse Public License v1.0
7    * which accompanies this distribution, and is available at
8    * http://www.eclipse.org/legal/epl-v10.html
9    * 
10   * Contributors: 
11   *   IBM - Initial API and implementation
12   *
13   * </copyright>
14   *
15   * $Id: OverrideableCommand.java,v 1.2 2005/06/08 06:17:05 nickb Exp $
16   */
17  package org.eclipse.emf.edit.command;
18  
19  
20  import java.util.Collection  ;
21  
22  import org.eclipse.emf.common.command.Command;
23  
24  
25  /**
26   * This represents a command that can be overridden by another command.
27   * The intended use of this is that an overrideable command should call 
28   * {@link org.eclipse.emf.edit.domain.EditingDomain#createOverrideCommand EditingDomain.createOverrideCommand}
29   * in its constructor to set up the override command.
30   * All its {@link Command} methods should then be guarded as follows:
31   * <pre>
32   *   public void execute()
33   *   {
34   *     if (getOverride() != null)
35   *     {
36   *       getOverride().execute();
37   *     }
38   *     else
39   *     {
40   *       doExecute();
41   *     }
42   *   }
43   * </pre>
44   * The contract with the overriding command is that the overrideable command will implement all its
45   * methods in corresponding doXxx methods, e.g., execute() is implemented in doExecute(), so that the
46   * overriding command can call back to the overrideable command's doXxx methods if it wants to extend
47   * rather than replace the original implementation.
48   * {@link AbstractOverrideableCommand} provides a convienient base implementation for overrideable commands.
49   */
50  public interface OverrideableCommand extends Command
51  {
52    /**
53     * This returns the command that overrides this command.
54     */
55    Command getOverride();
56  
57    /**
58     * This sets the command that overrides this command.
59     */
60    void setOverride(Command overrideCommand);
61  
62    /**
63     * This is overrideable command's implementation of canExecute.
64     */
65    boolean doCanExecute();
66  
67    /**
68     * This is overrideable command's implementation of execute.
69     */
70    void doExecute();
71  
72    /**
73     * This is overrideable command's implementation of canUndo.
74     */
75    boolean doCanUndo();
76  
77    /**
78     * This is overrideable command's implementation of undo.
79     */
80    void doUndo();
81  
82    /**
83     * This is overrideable command's implementation of redo.
84     */
85    void doRedo();
86  
87    /**
88     * This is overrideable command's implementation of getResult.
89     */
90    Collection   doGetResult();
91  
92    /**
93     * This is overrideable command's implementation of getAffectedObjects.
94     */
95    Collection   doGetAffectedObjects();
96  
97    /**
98     * This is overrideable command's implementation of getLabel.
99     */
100   String   doGetLabel();
101 
102   /**
103    * This is overrideable command's implementation of getDescription.
104    */
105   String   doGetDescription();
106 
107   /**
108    * This is overrideable command's implementation of dispose.
109    */
110   void doDispose();
111 }
112
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