Sorry ovid, but the code you posted as an example did not make that very clear*. You basically cannot get rid of namespace pollution in perl. It is impossible. Any piece of code can declare objects in any namespace at any time.
As far as /useful/ advice, :-), take a look at the top of Benchmark.pm and see how Jarkko did it.
* Update: i mean it didnt make your question clear. I know you arent a newbie. Remember we drank a fair amount of whiskey together in vienna? ;-)