001/*
002 * Sonar, open source software quality management tool.
003 * Copyright (C) 2008-2012 SonarSource
004 * mailto:contact AT sonarsource DOT com
005 *
006 * Sonar is free software; you can redistribute it and/or
007 * modify it under the terms of the GNU Lesser General Public
008 * License as published by the Free Software Foundation; either
009 * version 3 of the License, or (at your option) any later version.
010 *
011 * Sonar is distributed in the hope that it will be useful,
012 * but WITHOUT ANY WARRANTY; without even the implied warranty of
013 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014 * Lesser General Public License for more details.
015 *
016 * You should have received a copy of the GNU Lesser General Public
017 * License along with Sonar; if not, write to the Free Software
018 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02
019 */
020package org.sonar.api;
021
022/**
023 * Factory of extensions. It allows to dynamically create extensions depending upon runtime context. A use-case is
024 * to create one rule repository by language.
025 *
026 * <p>Notes :
027 * <ul>
028 * <li>the provider is declared in Plugin.getExtensions()</li>
029 * <li>the provider must also implement ServerExtension and/or BatchExtension</li>
030 * <li>the provider can accept dependencies (parameters) in its constructors.</li>
031 * <li>the method provide() is executed once by sonar</li>
032 * <li>the method provide() must return an object, a class or an Iterable of objects. <strong>Arrays are excluded</strong>.</li>
033 * </ul>
034 * </p>
035 *
036 * <p>Example:
037 * <pre>
038 * public class RuleRepositoryProvider extends ExtensionProvider implements ServerExtension {
039 *   private Language[] languages;
040 *
041 *   public RuleRepositoryProvider(Language[] languages) {
042 *     this.languages = languages;
043 *   }
044 *
045 *   public List<RuleRepository> provide() {
046 *     List<RuleRepository> result = new ArrayList<RuleRepository>();
047 *     for(Language language: languages) {
048 *       result.add(new RuleRepository(..., language, ...));
049 *     }
050 *     return result;
051 *   }
052 * }
053 * </pre>
054 * </p>
055 *
056 * @since 2.3
057 */
058public abstract class ExtensionProvider implements Extension {
059
060  public abstract Object provide();
061}