Lately I needed to call a listener function without an actual listener like so:

foo(null);

private function foo(event:Event):void
{
   //do something
}

So I was wondering if there is a significant difference regarding performance between this and using the following, in which I can prevent the null in calling the function without the listener, but am still able to call it with a listener as well:

foo();

private function foo(event:Event = null):void
{
}

I am not sure wether it is just a question of style, or actually bad practice and I should write two similar functions, one with and one without the event param (which seems cumbersome to me).

Looking forward to your opinions, thx.