Thanks Eric, On Fri, Sep 25, 2020 at 09:23:56AM +0100, Eric Wieser wrote: > Thanks for the PEP, and for pinging the numpy list about it. Some comments: > > Sequence unpacking remains a syntax error inside subscripts: > Reason: unpacking items would result it being immediately repacked into a > tuple > > A simple counter-example is [:, *args, :], which could be treated as > [(slice(None), *args, slice(None))]. > When there are index objects to the left or right of *args, it enables : > syntax in places that would otherwise be forbidden.
This use-case is persuasive to me. I recommend that the PEP be changed to allow `*args` inside subscripts. > Keyword-only subscripts are permitted. The positional index will be the > empty tuple > > As discussed on the numpy mailing list, a better approach might be to not > pass an argument at all, so that obj[spam=1, eggs=2] calls > type(obj).__getitem__(obj, spam=1, eggs=2). > Objects which want to support keyword-only indexing can provide a default > of their own (and are free to choose between () and None, while objects > which do not would just raise TypeError due to the missing positional > argument That's fine for getitem and delitem, but doesn't work with setitem. -- Steve _______________________________________________ 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/AKMR6WOE6HN5SQQAIBHVML6GPJTEY7TF/ Code of Conduct: http://python.org/psf/codeofconduct/
