what to do when instance of class fails to initialize ?

[Tom Van den Brandt]

Hello !

As you might have guessed, I'm one of those newbie-types, comming here,
asking questions and stuff...

Very specific question, it's probably a bit basic so forgive me if it's
stupid to ask...

If I have an __init__ for a class and the initialisation can't go through
(example: missing or wrong arguments), how do I return an error to the
caller (from main() function)?  When I do a return statement in the
__init__ it says __init__ should return None...  I can stop the flow with
raise 'BlahBlah'. But then the program exits.

What is the nice way to do this ? 

Tnx,  

-- 
Tom Van den Brandt
I try...