On Mon, May 10, 2021 at 12:49 PM Guido van Rossum <gu...@python.org> wrote: > > On Sun, May 9, 2021 at 5:08 PM Chris Angelico <ros...@gmail.com> wrote: >> >> On Mon, May 10, 2021 at 9:57 AM Steven D'Aprano <st...@pearwood.info> wrote: >> > >> > On Sun, May 09, 2021 at 04:45:55PM -0000, Thomas Grainger wrote: >> > >> > > now that python2.7 is EOL, it might be worth resurrecting this syntax >> > [...] >> > > except E1, E2, E3 as e: >> > >> > What advantages will this new syntax bring us? >> > >> > Will it allow us to do things that we can't currently do? >> > >> > When would you use it in preference to the existing syntax? By this I >> > mean both under what circumstances, and at what time (tomorrow? in a >> > year? in ten years?). >> > >> > Is there an aim beyond saving two characters? >> > >> >> It would remove a level of frustration. I've watched a lot of novice >> programmers, and some intermediate programmers, run into a source of >> (now completely unnecessary) pain that changing this: >> >> except ValueError: >> >> into this: >> >> except ValueError, TypeError: >> >> doesn't work. Yes, it's a quick SyntaxError, but the editor won't show >> it up (since most editors are Python 2 compatible, and wouldn't be >> checking this level of syntax anyway), so there's X amount of time >> spent coding, then go to run the thing, and it won't work the way they >> expect it to. > > > We've had arguments like this before, and we've usually taken the position > that we shouldn't compromise the language to cater to imperfect tools. > Editors that are Python-aware should just catch up with Python 3 syntax. > Editors that don't check this level of syntax definitely shouldn't be used as > motivation at all. > > (I just tried this in the latest VS Code Insiders edition, and the Python > support does catch this.) > > Also, I wonder what made those users think to try that? Maybe they read a > tutorial or StackOverflow issue suggesting the Python 2 syntax?
It's the obvious way to extend from a single exception name to two. Think of it *without* the "as" clause and it becomes less clear that the parentheses are necessary. > Someone else (Steven?) already pointed out in this thread that there are > other places where 'as <target>' or 'as <identifier>' as used, the relative > precedence of commas and 'as' is different than the proposal here: > >> It's true that adding "as e" makes it read oddly, but that's the only >> real point against it - other than a question of "when". > > > I think never is a perfectly fine answer. > I think "because of the possibility of the as clause, it's not worth doing this" is a perfectly fine answer too. It would be nice if "except TypeError, ValueError:" could be made valid, but that may not be worth the hassle. ChrisA _______________________________________________ Python-ideas mailing list -- python-ideas@python.org To unsubscribe send an email to python-ideas-le...@python.org https://mail.python.org/mailman3/lists/python-ideas.python.org/ Message archived at https://mail.python.org/archives/list/python-ideas@python.org/message/MGWLAJKBL5EC73L3TV4VQUHI3NADNDR3/ Code of Conduct: http://python.org/psf/codeofconduct/
