    001// Copyright 2009 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
    017import org.apache.tapestry5.ioc.ObjectCreator;
    018
    019/**
    020 * A <a href="http://en.wikipedia.org/wiki/Thunk">thunk</a> is a delayed calculation. In Java and Tapestry terms, a
    021 * Thunk is a proxy object of a particular interface that delegates all methods to an object of the same type obtained
    022 * from an {@link org.apache.tapestry5.ioc.ObjectProvider}. This is used by {@link
    023 * org.apache.tapestry5.ioc.services.LazyAdvisor} to build lazy thunk proxies.
    024 *
    025 * @since 5.1.0.1
    026 */
    027public interface ThunkCreator
    028{
    029    /**
    030     * Creates a Thunk of the given proxy type.
    031     *
    032     * @param proxyType     type of object to create (must be an interface)
    033     * @param objectCreator provides an instance of the same type on demand (may be invoked multiple times)
    034     * @param description   to be returned from the thunk's toString() method
    035     * @param <T>           type of thunk
    036     * @return thunk of given type
    037     */
    038    <T> T createThunk(Class<T> proxyType, ObjectCreator objectCreator, String description);
    039}