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/****************************************************************************
* Sangria *
* Copyright (C) 2014 Tavian Barnes <tavianator@tavianator.com> *
* *
* 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 com.tavianator.sangria.contextual;
import com.google.inject.Provider;
import com.google.inject.spi.InjectionPoint;
/**
* Like a {@link Provider}, but with knowledge of the target {@link InjectionPoint}.
*
* <p>
* This interface, along with {@link ContextSensitiveBinder}, is useful for injecting custom logger types, among other
* things. However, context-sensitive injections can make maintenance and debugging more difficult.
* </p>
*
* @author Tavian Barnes (tavianator@tavianator.com)
* @version 1.0
* @since 1.0
*/
public interface ContextSensitiveProvider<T> {
/**
* Provide an instance of {@code T} for the given context.
*
* @param injectionPoint The {@link InjectionPoint} for this provision.
* @return An instance of {@code T}.
*/
T getInContext(InjectionPoint injectionPoint);
/**
* Provide an instance of {@code T} for an unknown context.
* <p>
* The {@link InjectionPoint} may not be known in all cases, for example if a {@code Provider<T>} is used instead
* of
* a bare {@code T}. This method will be called in those cases.
* </p>
* <p>
* One reasonable implementation is to return a generically applicable instance, such as an anonymous logger.
* Another valid implementation is to throw an unchecked exception; in that case, {@code Provider<T>} injections
* will fail.
* </p>
*
* @return An instance of {@code T}
* @throws RuntimeException If injection without a context is not supported.
*/
T getInUnknownContext();
}
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