"Guido" == Guido van Rossum guido@CNRI.Reston.VA.US writes:
Guido> Yes, but class-based user exceptions existed many Python Guido> versions before class-based standard exceptions!
True, but I suspect that legacy class-based user exceptions are rare. I might be wrong, but you're absolutely right that these would all be broken.
Guido> Two examples in the standard library: ConfigParser.py and Guido> xdrlib.py.
Fortunately these are fixed with two 11 character patches :)
I'm not necessarily arguing for or against tightening this.