Update event_dispatcher.rst

Author: noniagriconomie

components/event_dispatcher.rst

@@ -348,8 +348,16 @@ of the event to dispatch::
     // creates the OrderPlacedEvent and dispatches it
     $event = new OrderPlacedEvent($order);
     $dispatcher->dispatch($event, OrderPlacedEvent::NAME);
-    // note that the second argument ``OrderPlacedEvent::NAME`` is optional,
-    // read more below in the subscriber code part
+
+.. versionadded:: 4.3
+
+Since Symfony 4.3, note that the event name is now optional in the :method:`Symfony\\Component\\EventDispatcher\\EventDispatcher::dispatch` method,
+so you can pass just the event object as first argument::
+
+    // ...
+    // creates the OrderPlacedEvent and dispatches it
+    $event = new OrderPlacedEvent($order);
+    $dispatcher->dispatch($event);
 
 Notice that the special ``OrderPlacedEvent`` object is created and passed to
 the ``dispatch()`` method. Now, any listener to the ``order.placed``
@@ -392,10 +400,9 @@ Take the following example of a subscriber that subscribes to the
                     ['onKernelResponsePre', 10],
                     ['onKernelResponsePost', -10],
                 ],
+                // when using two arguments, the event and the event name
                 OrderPlacedEvent::NAME => 'onStoreOrder',
-                // you can also subscribe this way if you pass only
-                // the event object as first argument and omit the second
-                // of the $dispatcher->dispatch method
+                // when using only one argument, the event only (Symfony 4.3+)
                 OrderPlacedEvent::class => 'onStoreOrder',
             ];
         }