com.google.inject.Scope Maven / Gradle / Ivy
/*
* Copyright (C) 2006 Google Inc.
*
* 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.google.inject;
/**
* A scope is a level of visibility that instances provided by Guice may have. By default, an
* instance created by the {@link Injector} has no scope, meaning it has no state from the
* framework's perspective -- the {@code Injector} creates it, injects it once into the class that
* required it, and then immediately forgets it. Associating a scope with a particular binding
* allows the created instance to be "remembered" and possibly used again for other injections.
*
* An example of a scope is {@link Scopes#SINGLETON}.
*
* @author [email protected] (Bob Lee)
*/
public interface Scope {
/**
* Scopes a provider. The returned provider returns objects from this scope. If an object does not
* exist in this scope, the provider can use the given unscoped provider to retrieve one.
*
*
Scope implementations are strongly encouraged to override {@link Object#toString} in the
* returned provider and include the backing provider's {@code toString()} output.
*
* @param key binding key
* @param unscoped locates an instance when one doesn't already exist in this scope.
* @return a new provider which only delegates to the given unscoped provider when an instance of
* the requested object doesn't already exist in this scope
*/
public Provider scope(Key key, Provider unscoped);
/**
* A short but useful description of this scope. For comparison, the standard scopes that ship
* with guice use the descriptions {@code "Scopes.SINGLETON"}, {@code "ServletScopes.SESSION"} and
* {@code "ServletScopes.REQUEST"}.
*/
@Override
String toString();
}