On Tue, Oct 12, 2021 at 4:51 AM Chris Angelico <ros...@gmail.com> wrote:
> > Exactly: simple usage of next is often a bug. We need to be careful > about this every time someone suggests that it's straight-forward to do > next(iter(obj)). > <snip> > Please give a real example of where calling first() and getting > ValueError is safer than calling next(iter(x)) and getting > StopIteration. So far, I am undeterred in believing that the two > exceptions have equivalent effect if the caller isn't expecting them. > I don't know about safer, but it is a clear example of why using next(iter(obj)) requires a pretty complete knowledge of the iteration protocol. I can guarantee you I'd get some questions from my students when they got a StopIterationError! If one DID write a first() function, it maybe or maybe not should raise a different exception, but it should certainly provide a better error message: >>> next(iter([])) Traceback (most recent call last): File "<stdin>", line 1, in <module> StopIteration Is not very helpful. -CHB > 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/2AL5FE3KZI4EBTRMJ7O5EL6MBVN7RUYF/ > Code of Conduct: http://python.org/psf/codeofconduct/ > -- Christopher Barker, PhD (Chris) Python Language Consulting - Teaching - Scientific Software Development - Desktop GUI and Web Development - wxPython, numpy, scipy, Cython
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