5 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
6 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
7 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
8 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
9 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
10 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
11 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
12 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
13 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
14 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
15 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
17 * This software consists of voluntary contributions made by many individuals
18 * and is licensed under the MIT license. For more information, see
19 * <http://www.doctrine-project.org>.
22 namespace Doctrine\Common;
25 * EventArgs is the base class for classes containing event data.
27 * This class contains no event data. It is used by events that do not pass state
28 * information to an event handler when an event is raised. The single empty EventArgs
29 * instance can be obtained through {@link getEmptyInstance}.
31 * @license http://www.opensource.org/licenses/lgpl-license.php LGPL
32 * @link www.doctrine-project.org
34 * @version $Revision: 3938 $
35 * @author Guilherme Blanco <guilhermeblanco@hotmail.com>
36 * @author Jonathan Wage <jonwage@gmail.com>
37 * @author Roman Borschel <roman@code-factory.org>
42 * @var EventArgs Single instance of EventArgs
44 private static $_emptyEventArgsInstance;
47 * Gets the single, empty and immutable EventArgs instance.
49 * This instance will be used when events are dispatched without any parameter,
50 * like this: EventManager::dispatchEvent('eventname');
52 * The benefit from this is that only one empty instance is instantiated and shared
53 * (otherwise there would be instances for every dispatched in the abovementioned form)
55 * @see EventManager::dispatchEvent
56 * @link http://msdn.microsoft.com/en-us/library/system.eventargs.aspx
59 public static function getEmptyInstance()
61 if ( ! self::$_emptyEventArgsInstance) {
62 self::$_emptyEventArgsInstance = new EventArgs;
65 return self::$_emptyEventArgsInstance;