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     */
017    
018    package org.apache.logging.log4j.core.util;
019    
020    /**
021     * A type of Plugin builder that can be used to configure and create a plugin instance using a Java DSL instead of
022     * through a configuration file. These builders are primarily useful for internal code and unit tests, but they can
023     * technically be used as a verbose alternative to configuration files.
024     *
025     * <p>
026     *     When creating plugin builders, it is customary to create the builder class as a public static inner class
027     *     called {@code Builder}. For instance, the builder class for
028     *     {@link org.apache.logging.log4j.core.layout.PatternLayout PatternLayout} would be
029     *     {@code PatternLayout.Builder}.
030     * </p>
031     *
032     * @param <T> the Plugin class this is a builder for.
033     */
034    public interface Builder<T> {
035    
036        /**
037         * Builds the plugin object after all configuration has been set. This will use default values for any
038         * unspecified attributes for the plugin.
039         *
040         * @return the configured plugin instance.
041         * @throws org.apache.logging.log4j.core.config.ConfigurationException if there was an error building the plugin
042         * object.
043         */
044        T build();
045    }