[Python-Dev] An interesting exception handling quirk (original) (raw)
Nick Coghlan ncoghlan at gmail.com
Sun Oct 20 12:24:25 CEST 2013
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On 20 October 2013 16:08, Armin Rigo <arigo at tunes.org> wrote:
Hi Nick,
On Sat, Oct 19, 2013 at 1:41 PM, Nick Coghlan <ncoghlan at gmail.com> wrote: recreating the exact exception subclass check from Python is actually difficult these days. Can't it be done roughly like that? def exit(self, typ, val, tb): try: raise typ, val except self.exceptions: return True except: return False
In Python 3, you have to use "raise type if val is None else val" instead, and you then have to deal with the fact that raise will overwrite an already set context on the exception value (contextlib.ExitStack actually has to work around that when unwinding the stack by restoring a more appropriate context value). But yes, actually reraising it does let you reproduce the exception matching.
That said, it actually occurs to me now that the current behaviour (overwriting an already set context) could arguably be considered a bug, since we don't overwrite an already set traceback.
Cheers, Nick.
-- Nick Coghlan | ncoghlan at gmail.com | Brisbane, Australia
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