tapestry-core/src/main/java/org/apache/tapestry5/services/EnvironmentalShadowBuilder.java

// Copyright 2007 The Apache Software Foundation
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package org.apache.tapestry5.services;

import org.apache.tapestry5.annotations.Environmental;
import org.apache.tapestry5.ioc.services.PropertyShadowBuilder;

/**
 * Much like {@link PropertyShadowBuilder}, except that instead of accessing a property of some other service, it
 * accesses a value from within the {@link Environment} service. This is useful for defining a new service that can be
 * injected into other services (whereas the {@link Environmental} annotation may only be used within component
 * classes).
 */
public interface EnvironmentalShadowBuilder
{
    /**
     * Returns a proxy that delegates all methods to an object obtained from {@link Environment#peekRequired(Class)}.
     * Note that at the time this method is invoked, the Environment service may still be virtual, and will often not
     * yet have been loaded with values, and that's OK, the resolution is deferred to the instant a method is invoked.
     *
     * @param <T>
     * @param serviceType the service type, which is used to obtained the delegate instance
     * @return a proxy to the service
     */
    <T> T build(Class<T> serviceType);
}