001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.wicket;
018
019/**
020 * Used to unify all metadata methods across the various objects.
021 * <p>
022 * This allows for metadata to be mutated at arms length without dealing with the intricacies of
023 * each type that implements it.
024 * <p>
025 * Due to the inability to refer to implementing types (e.g. Self in Rust) we use the {@code R} parameter
026 * to return the type of the implementing object.
027 *
028 * @param <B>
029 *            The base type the metadata object must extend. (e.g. {@link java.io.Serializable})
030 * @param <R>
031 *            The type of the implementing object.
032 * @author Jezza
033 * @see Application
034 * @see Component
035 * @see Session
036 * @see org.apache.wicket.request.cycle.RequestCycle
037 */
038public interface IMetadataContext<B, R extends IMetadataContext<B, R>>
039{
040        <T extends B> T getMetaData(MetaDataKey<T> key);
041
042        <T extends B> R setMetaData(MetaDataKey<T> key, T data);
043}