    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.MethodAdviceReceiver;
    018
    019/**
    020 * An advisor that identifies methods which can be evaluated lazily and advises them. A method can be evaluated lazily
    021 * if it returns an interface type and if it throws no checked exceptions. Lazy evaluation should be handled carefully,
    022 * as if any of the parameters to a method are mutable, or the internal state of the invoked service changes, the lazily
    023 * evaluated results may not match the immediately evaluated result. This effect is greatly exaggerated if the lazy
    024 * return object is evaluated in a different thread than when it was generated.
    025 * <p/>
    026 * Another consideration is that exceptions that would occur immediately in the non-lazy case are also deferred, often
    027 * losing much context in the process.
    028 * <p/>
    029 * Use laziness with great care.
    030 * <p/>
    031 * Use the {@link org.apache.tapestry5.ioc.annotations.NotLazy} annotation on methods that should not be advised.
    032 *
    033 * @since 5.1.0.0
    034 */
    035public interface LazyAdvisor
    036{
    037    void addLazyMethodInvocationAdvice(MethodAdviceReceiver methodAdviceReceiver);
    038
    039}