On Wed, Apr 22, 2020 at 01:26:02PM -0700, Andrew Barnert wrote: > > On Apr 21, 2020, at 16:02, Steven D'Aprano <st...@pearwood.info> wrote: > > > > On Tue, Apr 21, 2020 at 12:25:06PM -0700, Andrew Barnert via Python-ideas > > wrote: > >>> On Apr 21, 2020, at 01:36, Serhiy Storchaka <storch...@gmail.com> wrote: > >>> except ValueError: # assuming that’s the exception you want? > >> For what it’s worth, more_itertools.zip_equal raises an > >> UnequalIterablesError, which is a subclass of ValueError. > >> > >> I’m not sure whether having a special error class is worth it, but > >> that’s because nobody’s providing any examples of code where they’d > >> want to handle this error. Presumably there are cases where > >> something else in the expression could raise a ValueError for a > >> different reason, and being able to catch this one instead of that > >> one would be worthwhile. But how often? No idea. > > > >> At a guess, I’d say that if this has to be a builtin (whether > >> flag-switchable behavior in zip or a new builtin function) it’s > >> probably not worth adding a new builtin exception, but if it’s going > >> to go into itertools it probably is worth it. > > > > Why? > > Well, you quoted the answer above, but I’ll repeat it: [...]
I saw that, so let me rephrase my question: why it is worth a subclass if this is in itertools but not if it's a builtin? Sorry for being so terse in my question. You haven't really given an answer to that, as such, but I think that it is no longer relevant given the below. > For a little more detail: [...] > The question in every case is: do you often need to distinguish this case? Indeed. > As I said, I don’t know the answer to that question, because none of > the people saying they need an exception here have given any examples > where they’d want to handle the exception, and it’s hard to guess how > people want to handle an exception when you don’t even know where and > when they want to handle it. So I took a guess to start the > discussion. And that's the missing piece I was looking for, thank you. You weren't so much advocating for this as just exploring the options. Fair enough. -- Steven _______________________________________________ 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/TGWSKUKAKQOOB2E2D5CRB4DEZY4HPOCX/ Code of Conduct: http://python.org/psf/codeofconduct/
