    001// Licensed under the Apache License, Version 2.0 (the "License");
    002// you may not use this file except in compliance with the License.
    003// You may obtain a copy of the License at
    004//
    005//     http://www.apache.org/licenses/LICENSE-2.0
    006//
    007// Unless required by applicable law or agreed to in writing, software
    008// distributed under the License is distributed on an "AS IS" BASIS,
    009// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    010// See the License for the specific language governing permissions and
    011// limitations under the License.
    012
    013package org.apache.tapestry5.ioc.services;
    014
    015import org.apache.tapestry5.ioc.MethodAdviceReceiver;
    016
    017/**
    018 * An advisor that identifies methods which can be evaluated lazily and advises them. A method can be evaluated lazily
    019 * if it returns an interface type and if it throws no checked exceptions. Lazy evaluation should be handled carefully,
    020 * as if any of the parameters to a method are mutable, or the internal state of the invoked service changes, the lazily
    021 * evaluated results may not match the immediately evaluated result. This effect is greatly exaggerated if the lazy
    022 * return object is evaluated in a different thread than when it was generated.
    023 *
    024 * Another consideration is that exceptions that would occur immediately in the non-lazy case are also deferred, often
    025 * losing much context in the process.
    026 *
    027 * Use laziness with great care.
    028 *
    029 * Use the {@link org.apache.tapestry5.ioc.annotations.NotLazy} annotation on methods that should not be advised.
    030 *
    031 * @since 5.1.0.0
    032 */
    033public interface LazyAdvisor
    034{
    035    void addLazyMethodInvocationAdvice(MethodAdviceReceiver methodAdviceReceiver);
    036
    037}