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

[James Y Knight]

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