Steve said: "(This isn't Java or Ruby, where data-hiding is compulsory :-) "
At the risk of striking a sessile equine, when the attribute shouldn't be modified directly by client code, then you hide it and use a property to allow client code access. It is the idiom of allowing client code to edit read-write data directly via attributes that is pythonic, even though discouraged (somewhat) in other languages. Actually C# is mature enough for this idiom. C# and Python both support getter/setter methods that present as direct attribute access to client code, and thus allow you to refactor the class without breaking backwards compatibility. -- https://mail.python.org/mailman/listinfo/python-list
