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9 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
10 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
11 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
12 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
13 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
15 * This software consists of voluntary contributions made by many individuals
16 * and is licensed under the MIT license. For more information, see
17 * <http://www.doctrine-project.org>.
20 namespace Doctrine\Common;
23 * EventArgs is the base class for classes containing event data.
25 * This class contains no event data. It is used by events that do not pass state
26 * information to an event handler when an event is raised. The single empty EventArgs
27 * instance can be obtained through {@link getEmptyInstance}.
29 * @link www.doctrine-project.org
31 * @author Guilherme Blanco <guilhermeblanco@hotmail.com>
32 * @author Jonathan Wage <jonwage@gmail.com>
33 * @author Roman Borschel <roman@code-factory.org>
38 * Single instance of EventArgs.
42 private static $_emptyEventArgsInstance;
45 * Gets the single, empty and immutable EventArgs instance.
47 * This instance will be used when events are dispatched without any parameter,
48 * like this: EventManager::dispatchEvent('eventname');
50 * The benefit from this is that only one empty instance is instantiated and shared
51 * (otherwise there would be instances for every dispatched in the abovementioned form).
53 * @see EventManager::dispatchEvent
55 * @link http://msdn.microsoft.com/en-us/library/system.eventargs.aspx
59 public static function getEmptyInstance()
61 if ( ! self::$_emptyEventArgsInstance) {
62 self::$_emptyEventArgsInstance = new EventArgs;
65 return self::$_emptyEventArgsInstance;