    001// Copyright 2011 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.plastic;
    016
    017/**
    018 * MethodAdvice is a special callback that is threaded into the implementation of a method.
    019 * The advice recieves a {@link MethodInvocation}, which gives the advice the ability to change
    020 * parameters or return values or thrown exceptions. In many cases, new behavior is added around the method invocation
    021 * with affecting it; common examples include logging, null checks, transaction management, or security checks.
    022 */
    023public interface MethodAdvice
    024{
    025    /**
    026     * Advise the method, usually invoking {@link MethodInvocation#proceed()} at some point.
    027     * The advice is free to inspect and even replace parameters. Most
    028     * Aspects will then invoke {@link MethodInvocation#proceed()}. The advice may then inspect and
    029     * replace any checked thrown exceptions. Some advice (for example, caching) may selectively decide to bypass the
    030     * invocation entirely, and instead invoke some other method or otherwise set a return value or thrown exception.
    031     *
    032     * @param invocation
    033     *            identifies the method being invoked, including parameters
    034     */
    035    void advise(MethodInvocation invocation);
    036}