[Python-Dev] Pre-PEP: Exception Reorganization for Python 3.0 (original) (raw)

Brett Cannon bcannon at gmail.com
Sat Jul 30 21:20:49 CEST 2005

On 7/30/05, James Y Knight <foom at fuhm.net> wrote:

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.

The reason for requiring inheriting from Raisable is so that the basic interface will be guaranteed for any caught exception. And I don't think that any of the built-ins have any specific attributes sans maybe OSError, but that is a leaf in the inheritance tree so that is not a problem.

Don't worry, the interfaces won't change in the middle of a branch.

-Brett

More information about the Python-Dev mailing list