user/src/com/google/web/bindery/event/shared/HandlerRegistration.java

/*
 * Copyright 2011 Google Inc.
 * 
 * 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.google.web.bindery.event.shared;

/**
 * Registration objects returned when an event handler is bound (e.g. via
 * {@link EventBus#addHandler}), used to deregister.
 * <p>
 * A tip: to make a handler deregister itself try something like the following:
 * <code><pre>new MyHandler() {
 *  HandlerRegistration reg = MyEvent.register(eventBus, this);
 * 
 *  public void onMyThing(MyEvent event) {
 *    {@literal /}* do your thing *{@literal /}
 *    reg.removeHandler();
 *  }
 * };
 * </pre></code>
 */
public interface HandlerRegistration {

  /**
   * Deregisters the handler associated with this registration object if the
   * handler is still attached to the event source. If the handler is no longer
   * attached to the event source, this is a no-op.
   */
  void removeHandler();
}