    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
    015    package 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     */
    023    public 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    }