    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
    015    package org.apache.tapestry5.ioc.services;
    016
    017    import 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     */
    035    public interface LazyAdvisor
    036    {
    037        void addLazyMethodInvocationAdvice(MethodAdviceReceiver methodAdviceReceiver);
    038
    039    }