/*******************************************************************************
 * Copyright (c) 1998, 2008 Oracle. All rights reserved.
 * This program and the accompanying materials are made available under the 
 * terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0 
 * which accompanies this distribution. 
 * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
 * and the Eclipse Distribution License is available at 
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * Contributors:
 *     Oracle - initial API and implementation from Oracle TopLink
 ******************************************************************************/  
package org.eclipse.persistence.indirection;


/**
 * <b>Purpose</b>: Interface to allow lazy loading of an object's relationships from the database.
 *
 * @see ValueHolder
 * @see org.eclipse.persistence.internal.indirection.DatabaseValueHolder
 */
public interface ValueHolderInterface extends Cloneable {

    /** Can be used to have transparent indirection toString instantiate the objects. */
    public static boolean shouldToStringInstantiate = false;

    /**
     * PUBLIC:
     * Copy the value holder (but not its' reference, shallow).
     */
    public Object clone();
    
    /**
     * PUBLIC:
     * Return the value.
     */
    public Object getValue();

    /**
     * PUBLIC:
     * Return whether the contents have been read from the database.
     * This is used periodically by the indirection policy to determine whether
     * to trigger the database read.
     */
    public boolean isInstantiated();

    /**
     * PUBLIC:
     * Set the value.
     */
    public void setValue(Object value);
}