// Copyright 2008 The Apache Software Foundation

 //

 // Licensed under the Apache License, Version 2.0 (the "License");

 // you may not use this file except in compliance with the License.

 // You may obtain a copy of the License at

 //

 //     http://www.apache.org/licenses/LICENSE-2.0

 //

 // Unless required by applicable law or agreed to in writing, software

 // distributed under the License is distributed on an "AS IS" BASIS,

 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 // See the License for the specific language governing permissions and

 // limitations under the License.

 package org.apache.tapestry5;

 import javax.servlet.http.HttpSessionBindingEvent;

 import javax.servlet.http.HttpSessionBindingListener;

 /**

  * Base implementation of {@link org.apache.tapestry5.OptimizedSessionPersistedObject}.  Subclasses should invoke {@link

  * #markDirty()} when internal state of the object changes.

  *

  * @since 5.1.1.0

  */

 public abstract class BaseOptimizedSessionPersistedObject implements OptimizedSessionPersistedObject, HttpSessionBindingListener

 {

     private transient boolean dirty;

     public final boolean isSessionPersistedObjectDirty()

     {

         return dirty;

     }

     /**

      * Invoked by the servlet container when the value is stored (or re-stored) as an attribute of the session. This

      * clears the dirty flag. Subclasses may override this method, but should invoke this implementation.

      */

     public void valueBound(HttpSessionBindingEvent event)

     {

         dirty = false;

     }

     /**

      * Does nothing.

      */

     public void valueUnbound(HttpSessionBindingEvent event)

     {

     }

     /**

      * Invoked by the subclass whenever the internal state of the object changes. Typically, this is invoked from

      * mutator methods.

      */

     protected final void markDirty()

     {

         dirty = true;

     }

 }