/*
* 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.gwt.sample.ui.client;
import com.google.gwt.user.client.ui.IsWidget;
import com.google.web.bindery.event.shared.EventBus;
/**
* Implemented by specialized widget drivers that can answer
* {@link com.google.gwt.activity.shared.Activity#mayStop() mayStop()} calls for
* {@link com.google.gwt.activity.shared.Activity Activities}.
* <p>
* Note that this interface extends {@link IsWidget}. This is to make it easier
* to evolve app code in MVP directions piecemeal, just where it is useful. If
* code that assembles widgets thinks of them strictly as IsWidget instances, it
* doesn't need to notice as they get refactored in to Presenter / View pairs.
* Or as they don't.
*/
public interface PresentsWidgets extends IsWidget {
/**
* Called (probably from
* {@link com.google.gwt.activity.shared.Activity#mayStop Activity.mayStop})
* to see if it's safe to stop this presenter.
*
* @return null if it's okay to stop, else a message to ask the user if she's
* sure
*/
String mayStop();
void start(EventBus eventBus);
void stop();
}