Imagine the following situation:

  function foo()
  {
    // get arguments for call of foo()
    $arg_list = func_get_args();

    // call another function, depending on $arg_list
    // and passing parts of $arg_list as parameters
    call_user_func( "bar", /* how can i put here a 
                              variable number of
                              arguments? */
                   );
  }