[Python-Dev] Pre-PEP: Exception Reorganization for Python 3.0

Sat Jul 30 14:37:15 CEST 2005

On Jul 29, 2005, at 11:07 PM, Robert Brewer wrote:
> I'd recommend not subclassing SystemExit--there are too many programs
> out there which expect the argument (e.g. sys.exit(3)) to mean 
> something
> specific, but that expectation doesn't apply at all to SystemError.

Yes please make note of this for *all* exception (and otherwise) 
inheritance. You must ensure that any exception B that inherits from 
A conforms to A's interface! If that isn't the case, it shouldn't 
inherit. Lots of people seem to forget this, and it's always a pain 
in the ass.
James