    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
    015    package org.apache.tapestry5.ioc.services;
    016
    017    import 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     */
    027    public 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    }