cvs commit: jakarta-avalon-excalibur/src/scratchpad/org/apache/avalon/excalibur/system/util OverridableContext.java

[bloritsch]

bloritsch    02/03/13 06:41:00

  Added:       src/scratchpad/org/apache/avalon/excalibur/system/util
                        OverridableContext.java
  Log:
  add overridable context
  
  Revision  Changes    Path
  1.1                  
jakarta-avalon-excalibur/src/scratchpad/org/apache/avalon/excalibur/system/util/OverridableContext.java
  
  Index: OverridableContext.java
  ===================================================================
  /*
   * Copyright (C) The Apache Software Foundation. All rights reserved.
   *
   * This software is published under the terms of the Apache Software License
   * version 1.1, a copy of which has been included  with this distribution in
   * the LICENSE.txt file.
   */
  package org.apache.avalon.excalibur.system.util;
  
  import org.apache.avalon.framework.context.*;
  
  /**
   * The OverridableContext allows you to "null" out entries, even if they are
   * in a parent context.
   *
   * @author <a href="mailto:[EMAIL PROTECTED]">Berin Loritsch</a>
   * @version CVS $Revision: 1.1 $ $Date: 2002/03/13 14:41:00 $
   * @since 4.1
   */
  public final class OverridableContext extends DefaultContext
  {
      private final Null m_null = new Null();
  
      public OverridableContext()
      {
          super();
      }
  
      public OverridableContext( Context parent )
      {
          super( parent );
      }
  
      public Object get( String key )
          throws ContextException
      {
          Object value = super.get( key );
  
          if ( m_null.equals( value ) )
          {
              throw new ContextException("Could not return value for " + key);
          }
  
          return value;
      }
  
      public void put( String key, Object value )
      {
          super.put( key, (value == null) ? new Null() : value );
      }
  
      private final static class Null
      {
          public boolean equals( Object other )
          {
              return other instanceof Null;
          }
  
          public int hashcode()
          {
              return 0;
          }
  
          public String toString()
          {
              return "null";
          }
      }
  }
  
  
  

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