001// Copyright 2011 The Apache Software Foundation
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
007// http://www.apache.org/licenses/LICENSE-2.0
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.
015package org.apache.tapestry5.plastic;
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
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);