    001// Copyright 2007 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.services;
    016
    017import org.apache.tapestry5.annotations.Environmental;
    018import org.apache.tapestry5.ioc.services.PropertyShadowBuilder;
    019
    020/**
    021 * Much like {@link PropertyShadowBuilder}, except that instead of accessing a property of some other service, it
    022 * accesses a value from within the {@link Environment} service. This is useful for defining a new service that can be
    023 * injected into other services (whereas the {@link Environmental} annotation may only be used within component
    024 * classes).
    025 */
    026public interface EnvironmentalShadowBuilder
    027{
    028    /**
    029     * Returns a proxy that delegates all methods to an object obtained from {@link Environment#peekRequired(Class)}.
    030     * Note that at the time this method is invoked, the Environment service may still be virtual, and will often not
    031     * yet have been loaded with values, and that's OK, the resolution is deferred to the instant a method is invoked.
    032     *
    033     * @param <T>
    034     * @param serviceType the service type, which is used to obtained the delegate instance
    035     * @return a proxy to the service
    036     */
    037    <T> T build(Class<T> serviceType);
    038}