Would it be possible to drop the requirement that multiple exception types are parenthesized? Is it only ambiguous with the old Python2 syntax?

On Sat, 8 May 2021, 20:15 Guido van Rossum, <guido@python.org> wrote:

I propose “exception tuple”, since syntactically and semantically it must be a tuple. (Same as for isinstance() and issubclass().)

On Sat, May 8, 2021 at 05:52 Thomas Grainger <tagrain@gmail.com> wrote:

That's this bit:

```
    except (A, B):
           ^^^^^^
```

bpo-43149 currently calls it an "exception group", but that conflicts with PEP 654 -- Exception Groups and except*

```

   >>> try:
   ...   pass
   ... except A, B:
   ...   pass
   Traceback (most recent call last):
   SyntaxError: exception group must be parenthesized
```

some alternatives:

exception classinfo must be parenthesized (classinfo so named from the parameter to issubclass)
exception sequence must be parenthesized

see also:

- https://github.com/python/cpython/pull/24467#discussion_r628756347
- https://www.python.org/dev/peps/pep-0654/
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--Guido (mobile)