Polymorphic


1   /*
2    * Copyright (C) 2003  Christian Cryder [christianc@granitepeaks.com]
3    *
4    * This library is free software; you can redistribute it and/or
5    * modify it under the terms of the GNU Lesser General Public
6    * License as published by the Free Software Foundation; either
7    * version 2.1 of the License, or (at your option) any later version.
8    *
9    * This library is distributed in the hope that it will be useful,
10   * but WITHOUT ANY WARRANTY; without even the implied warranty of
11   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
12   * Lesser General Public License for more details.
13   *
14   * You should have received a copy of the GNU Lesser General Public
15   * License along with this library; if not, write to the Free Software
16   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
17   *
18   * $Id: Polymorphic.java,v 1.5 2004/02/01 05:16:28 christianc Exp $
19   */
20  package org.enhydra.barracuda.core.event;
21  
22  import java.io.*;
23  import java.util.*;
24  
25  /**
26   * This interface indicates an Event is Polymorphic, in
27   * the sense that firing it causes parent events to be fired 
28   * first. For instance, if MyEvent extends PolymorphicEvent,
29   * firing MyEvent first causes a PolymorphicEvent to be fired
30   * because MyEvent _is_ a PolymorphicEvent. Kapish?
31   *
32   * This type of functionality makes it possible to install
33   * listeners on a parent event and be notified when any of the 
34   * child events are fired...this is sometimes very useful.
35   * 
36   * This interface has kind of the opposite meaning of the 
37   * Exception interface. Events should never indicate both 
38   * Exceptional and Polymorphic (and can't because both of these 
39   * interfaces define describeEventChainingStrategy())
40   */
41  public interface Polymorphic {
42      /**
43       * Describe the event chaining stategy. This method really
44       * serves to ensure that objects cannot implement BOTH
45       * Polymorphic and Exceptional (it's got to be one or the other)
46       *
47       * @return string describing the event chain strategy
48       */
49      public String   describeEventChainingStrategy();
50  }
51
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