/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.beam.sdk.options;
/**
* An interface used with the {@link Default.InstanceFactory} annotation to specify the class that
* will be an instance factory to produce default values for a given getter on
* {@link PipelineOptions}. When a property on a {@link PipelineOptions} is fetched, and is
* currently unset, the default value factory will be instantiated and invoked.
*
* <p>Care must be taken to not produce an infinite loop when accessing other fields on the
* {@link PipelineOptions} object.
*
* @param <T> The type of object this factory produces.
*/
public interface DefaultValueFactory<T> {
/**
* Creates a default value for a getter marked with {@link Default.InstanceFactory}.
*
* @param options The current pipeline options.
* @return The default value to be used for the annotated getter.
*/
T create(PipelineOptions options);
}