On 10/24/2010 4:48 AM, Martin v. Loewis wrote: > Am 24.10.2010 07:01, schrieb Steve Holden: >> I was somewhat surprised to discover that Python 3 no longer allows an >> exception to be raised in an except clause (or rather that it reports it >> as a separate exception that occurred during the handling of the first). > > I think you are misinterpreting what you are seeing. The exception being > raised actually *is* an attribute error, and it actually is the > attribute error that gets reported. It's only that reporting an > exception that has a __context__ first reports the context, then reports > the actual exception. > I don't believe I *am* misinterpreting it. The fact of the matter is that the context is irrelevant to the user, and there should be some way to suppress it to avoid over-complicating the traceback.
This behavior is quite reasonable during testing, but I would prefer to exclude an explicit raise directly in the except handler since that is hardly to be construed as accidental (whereas an exception in a function called in the handler perhaps *should* be reported). > You may now wonder whether it is possible to set __context__ to None > somehow. See PEP 3134: > > Open Issue: Suppressing Context > > As written, this PEP makes it impossible to suppress '__context__', > since setting exc.__context__ to None in an 'except' or 'finally' > clause will only result in it being set again when exc is raised. > I have already read that. Peter Otten has separately explained how to suppress the behavior using sys.excepthook, which appears to be a halfway satisfactory solution. regards Steve -- Steve Holden +1 571 484 6266 +1 800 494 3119 PyCon 2011 Atlanta March 9-17 http://us.pycon.org/ See Python Video! http://python.mirocommunity.org/ Holden Web LLC http://www.holdenweb.com/ -- http://mail.python.org/mailman/listinfo/python-list
