[Python-Dev] Exceptions must? be old-style classes? (original) (raw)

Phillip J. Eby pje at telecommunity.com
Sun Jan 16 03:22:28 CET 2005

At 05:57 PM 1/15/05 -0800, Guido van Rossum wrote:

It's been suggested that all exceptions should inherit from Exception, but this would break tons of existing code, so we shouldn't enforce that until 3.0. (Is there a PEP for this? I think there should be.)

Couldn't we require new-style exceptions to inherit from Exception? Since there are no new-style exceptions that work now, this can't break existing code. Then, the code path is just something like:

 if isinstance(ob,Exception):
     # it's an exception, use its type

 else:
     # all the other tests done now

This way, the other tests that would be ambiguous wrt new-style classes can be skipped, but non-Exception classic classes would still be handled by the existing checks.

Or am I missing something?

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