My conclusion is that you should ignore PEP 8 for your use case and write “if len(a) == 0”.
On Wed, Aug 25, 2021 at 06:13 Tim Hoffmann via Python-ideas < python-ideas@python.org> wrote: > Guido van Rossum wrote: > > So then the next question is, what's the use case? What code are people > > writing that may receive either a stdlib container or a numpy array, and > > which needs to do something special if there are no elements? Maybe > > computing the average? AFAICT Tim Hoffman (the OP) never said. > > There's two parts to the answer: > > 1) There functions e.g. in scipy and matplotlib that accept both numpy > arrays and lists of flows. Speaking from matplotlib experience: While > eventually we coerce that data to a uniform internal format, there are > cases in which we need to keep the original data and only convert on a > lower internal level. We often can return early in a function if there is > no data, which is where the emptiness check comes in. We have to take extra > care to not do the PEP-8 recommended emptiness check using `if not data`. > > 2) Even for cases that cannot have different types in the same code, it is > unsatisfactory that I have to write `if not seq` but `if len(array) == 0` > depending on the expected data. IMHO whatever the recommended syntax for > emptiness checking is, it should be the same for lists and arrays and > dataframes. > _______________________________________________ > 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/Q6KZEXFLJ6TEFSDQM3SXXIVGNFNURPYT/ > Code of Conduct: http://python.org/psf/codeofconduct/ > -- --Guido (mobile)
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