/*******************************************************************************
 * Copyright (c) 2005, 2006 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 * Port to the D programming language:
 *     Frank Benoit <benoit@tionex.de>
 *******************************************************************************/

module org.eclipse.core.commands.IStateListener;

import org.eclipse.core.commands.State;

/**
 * <p>
 * A listener to changes in some state.
 * </p>
 * <p>
 * Clients may implement, but must not extend this interface.
 * </p>
 *
 * @since 3.2
 */
public interface IStateListener {

    /**
     * Handles a change to the value in some state.
     *
     * @param state
     *            The state that has changed; never <code>null</code>. The
     *            value for this state has been updated to the new value.
     * @param oldValue
     *            The old value; may be anything.
     */
    public void handleStateChange(State state, Object oldValue);
}