Question

We have a object method that returns a city/state tuple, i.e. ('Boston', 'MA'). Under some valid circumstances, there is no valid city/state to return. Stylistically, does it make more sense to return None, or a two element tuple containing (None, None) in that case?

Answer 1

I would return None. If there is no result, why return something that looks like a result?

It is also easier to test:

result = getCity()
if result:
   # do something

I would only return (None, None) if it were possible that only one of the two values is None (i.e. ('Boston', None)). It would be more consistent in this case.