Overloading methods in R

(1) It seems to me that, generally, in R it is not possible to overload 
functions. Is that right?

(2) Assuming that the above is true, or partially true, is there any extra 
packages to handle overloading in R?

(3) Assuming (1) is TRUE and (2) is FALSE, can anyone provide some advice on 
developing some function that understand what the arguments are and then 
calls the right overloaded function?

It would be something like this:

overloadedFunction1 <- function(x) {};

overloadedFunction2 <- function(x, y) {};

theFunction <- function(...)
{
   # How to identify ... and call the right overloaded function?
}