/*
 * Copyright 2002-2016 jamod & j2mod development teams
 *
 * 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 com.ghgande.j2mod.modbus.util;

/**
 * A cleanroom implementation of the Observer interface
 * for the Observable design pattern.
 *
 * @author Dieter Wimberger (wimpi)
 * @author Steve O'Hara (4NG)
 * @version 2.0 (March 2016)
 */
public interface Observer {

    /**
     * Updates the state of this <tt>Observer</tt> to be in
     * synch with an <tt>Observable</tt> instance.
     * The argument should usually be an indication of the
     * aspects that changed in the <tt>Observable</tt>.
     *
     * @param o   an <tt>Observable</tt> instance.
     * @param arg an arbitrary argument to be passed.
     */
    void update(Observable o, Object arg);

}