001// Copyright 2006 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.ioc.services; 016 017/** 018 * Creates a "shadow" of a property of an object. The shadow has the same type as the property, and delegates all method 019 * invocations to the property. Each method invocation on the shadow re-acquires the value of the property from the 020 * underlying object and delegates to the current value of the property. 021 * <p/> 022 * Typically, the object in question is another service, one with the "perthread" service lifecycle. This allows a 023 * global singleton to shadow a value that is specific to the current thread (and therefore, the current request). 024 */ 025public interface PropertyShadowBuilder 026{ 027 /** 028 * @param <T> 029 * @param source the object from which a property will be extracted 030 * @param propertyName the name of a property of the object, which must be readable 031 * @param propertyType the expected type of the property, the actual property type must be assignable to this type 032 * @return the shadow 033 */ 034 <T> T build(Object source, String propertyName, Class<T> propertyType); 035}