Register session in function without global?

I am trying to register a session variable in a function without using the global in the beginning. The reason for this is that I don´t always know how many variables I am going to register (I separate the different fields with | like this, "username|email|cellphone" and explode them). Is there some way I can make all the variables in the function global, so I can get the session variables registered? function test() { global $username // <-- With this, it works. Without it, it doesn´t session_start(); $username="tobias"; session_register("username"); } The best I could come up with was (didn´t work): global $HTTP_SESSION_VARS; Any thoughts? // Tobias