server/lib/private/Hooks/Emitter.php

<?php
/**
 * @copyright Copyright (c) 2016, ownCloud, Inc.
 *
 * @author Jörn Friedrich Dreyer <jfd@butonic.de>
 * @author Morris Jobke <hey@morrisjobke.de>
 * @author Robin Appelman <robin@icewind.nl>
 *
 * @license AGPL-3.0
 *
 * This code is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License, version 3,
 * as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License, version 3,
 * along with this program.  If not, see <http://www.gnu.org/licenses/>
 *
 */

namespace OC\Hooks;

/**
 * Class Emitter
 *
 * interface for all classes that are able to emit events
 *
 * @package OC\Hooks
 */
interface Emitter {
	/**
	 * @param string $scope
	 * @param string $method
	 * @param callable $callback
	 * @return void
	 */
	public function listen($scope, $method, callable $callback);

	/**
	 * @param string $scope optional
	 * @param string $method optional
	 * @param callable $callback optional
	 * @return void
	 */
	public function removeListener($scope = null, $method = null, callable $callback = null);
}