__slots__, setattr, __metaclass__

[Roman Yakovenko]

	Hi. I have small problem and I don't know solution.
The problem: every class imported from some module X should not allow to be modified
( modified == adding or deleting new class attributes ). 
Small explanation about what I am doing: I has complex dll written in Managed C++ for C#.
I am using "Python for .NET" and python unittest module to test my dll. 
I find myself often make a mistake in attributes names. I'd like to protect my self from those errors.
In subject I listed available options, but I don't know which one to pick and how to use it in my situation.

As you can guess I can't to modify Managed C++ sources.

Thanks. Roman.