On 26Feb2021 02:44, Irit Katriel <iritkatriel@googlemail.com> wrote:
On Fri, Feb 26, 2021 at 2:00 AM Guido van Rossum <guido@python.org> wrote:
OT: Is ExceptionGroup *really* immutable in the current implementation? As long as the 'errors' field is a list, I think one could mutate the list directly.
It's not, but we were going to make it an immutable tuple.
Could you say why? Other than wanting to discourage mutation happy code getting out there? The reason I ask is that the scenario which comes to my mind is something like: except *OSError as e: AIUI "e" is an ExceptionGroup containing only OSErrors. So, one common thing in my own code is this: try: do something with a file except OSError as e: if e.errno == ENOENT: # file is missing, but that is ok # because we treat it like an empty file elif ... some other ok situation ... else: raise My natural inclination with an ExceptionGroup would be to winnow the OSErrors I'm handed, and push the _unhandled_ errors back into the original ExceptionGroup. That way, after the various except* clauses, a nonempty ExceptionGroup would remain with the unhandled errors, and it might perhaps be reraised then. Cheers, Cameron Simpson <cs@cskk.id.au>