    001// Copyright 2006, 2008 The Apache Software Foundation
    002//
    003// Licensed under the Apache License, Version 2.0 (the "License");
    004// you may not use this file except in compliance with the License.
    005// You may obtain a copy of the License at
    006//
    007//     http://www.apache.org/licenses/LICENSE-2.0
    008//
    009// Unless required by applicable law or agreed to in writing, software
    010// distributed under the License is distributed on an "AS IS" BASIS,
    011// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    012// See the License for the specific language governing permissions and
    013// limitations under the License.
    014
    015package org.apache.tapestry5.internal.util;
    016
    017import org.apache.tapestry5.ComponentEventCallback;
    018
    019/**
    020 * A {@link org.apache.tapestry5.ComponentEventCallback} used for notification events. Event handler methods may return
    021 * true (to abort the event) or false (to allow the event to continue bubbling up), but all other values are forbidden.
    022 */
    023public class NotificationEventCallback implements ComponentEventCallback
    024{
    025    private final String eventType;
    026
    027    private final String completeId;
    028
    029    public NotificationEventCallback(String eventType, String completeId)
    030    {
    031        this.eventType = eventType;
    032        this.completeId = completeId;
    033    }
    034
    035    public boolean handleResult(Object result)
    036    {
    037        if (result instanceof Boolean) return ((Boolean) result);
    038
    039        throw new IllegalArgumentException(
    040                String.format("Event '%s' from %s received an event handler method return value of %s. This type of event does not support return values from event handler methods.", eventType, completeId, String
    041                        .valueOf(result)));
    042    }
    043
    044}