I know this is not the point of this thread, but when i saw: ``` numbers = (i for i in range(10)) assert 3 in numbers next(numbers) # 4! ``` I was totally surprised that generator expressions support `in` -- WTF? they very much are NOT containers! And, in fact, all iterators support `in` -- wow, just wow. I know this is not going to change, but it strikes me as a greater source of mysterious bugs than not getting an error from iterating an exhausted iterator. Getting back OT: The distinction between iterators and containers is simply something that you need to learn -- it's an inevitable consequence of the benefits of iterators. And the original example is an easy one -- Python supports both list comprehensions and generator comprehensions -- you really need to know which to use when. -CHB On Tue, Jun 13, 2023 at 4:18 PM Chris Angelico <rosuav@gmail.com> wrote:
On Wed, 14 Jun 2023 at 09:05, BoppreH via Python-ideas <python-ideas@python.org> wrote:
@ChrisA: There are already flags for enabling warnings on dangerous
bytearray comparisons[1] or relying on locale-dependent encodings[2], not to mention a whole Development Mode flag[3] that adds extra checks. Some of those checks affect fewer people than my proposal. A "warn on reused generators" flag would fit right in, maintain backwards compatibility, and help some people (admittedly less than an opt-out one).
Citation needed, how do you calculate that they affect fewer people than your proposal? The byte/str comparison warning relates to Py2/Py3 changes, which affected huge numbers of people; locale-dependent encodings affect everyone whose systems default to those encodings; and I don't know what the debug build does exactly, but it's specifically meant to cover things that are too expensive to check for normally.
Also, question: Would your proposal even be useful to people if they had to run Python with a special parameter to get it? Wouldn't it be just as easy to shadow iter(), like I have already suggested multiple times as a much better way to do this?
And then Chris' messages started rolling in.
Backward compatibility is WAY more important than a lot of proposals seem to acknowledge. You're welcome to hate me for saying it, but frankly, you're also welcome to ignore my posts. I don't have to prove anything to you; the onus is on you to demonstrate the value of your proposal, and at the moment, you've shown a benefit in a very small number of cases, contrasted with a potentially huge number of situations where this would create a spurious warning.
Blaming me for the pushback is a tad unfair. But that's your prerogative.
ChrisA _______________________________________________ Python-ideas mailing list -- python-ideas@python.org To unsubscribe send an email to python-ideas-leave@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/RHQWRD... 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