001// Copyright 2004, 2005 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.tapestry.event; 016 017/** 018 * May observe changes in an object's properties. This is a "weak" variation 019 * on JavaBean's style bound properties. It is used when there will be at most 020 * a single listener on property changes, and that the listener is not interested 021 * in the old value. 022 * 023 * @author Howard Lewis Ship 024 * 025 **/ 026 027public interface ChangeObserver 028{ 029 /** 030 * Sent when the observed object changes a property. The event identifies 031 * the object, the property and the new value. 032 * 033 **/ 034 035 public void observeChange(ObservedChangeEvent event); 036}