001// Copyright 2007 The Apache Software Foundation
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
007//     http://www.apache.org/licenses/LICENSE-2.0
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.
015package org.apache.tapestry5.services;
017import org.apache.tapestry5.annotations.Environmental;
018import org.apache.tapestry5.ioc.services.PropertyShadowBuilder;
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
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);