On Thu, Feb 6, 2020 at 3:47 AM Brandt Bucher <brandtbuc...@gmail.com> wrote: > > > I have one suggestion: Wouldn't it be useful for these operators to also > > accept sets (functionally acting like a dict with None for all values)? > > > Why None? Why not 0, or False, or 42? This sort of thing belongs more in > > a function or method, IMHO. > > Well, in their defense, None is the null object in Python, so it would be a > natural choice. With that said, I am strongly against this for several > reasons: > > - The proposal in its current form is very easy to wrap your head around: "|" > takes dicts, "|=" takes anything dict.update does. > - Python doesn't allow sets to be dictionaries anywhere else. It's much more > natural to use a dict like a set than to use a set like a dict. Hence, this > PEP! > - A consistent argument that we've gotten since the very beginning is > something to the effect of "I don't know what types are being used in the > expression 'a | b'." While we argue that this isn't the issue in practice > that people make it out to be, accepting sets here would definitely muddy the > waters. >
- and you can use dict.fromkeys to "upgrade" a set to a dict anyway. If this goes through as is, and then in a few years' time we start seeing lots of people begging to be able to skip the explicit fromkeys and accept sets directly, it can be addressed then. Personally, I think sets make good sense on the right hand side of an intersection (as a means of saying "whitelist the keys to this set"; values would be irrelevant there anyway), but not with union/update. ChrisA _______________________________________________ Python-Dev mailing list -- python-dev@python.org To unsubscribe send an email to python-dev-le...@python.org https://mail.python.org/mailman3/lists/python-dev.python.org/ Message archived at https://mail.python.org/archives/list/python-dev@python.org/message/NZWJDWAHGJSOMI23ZAU5CDEC4BHJMFRT/ Code of Conduct: http://python.org/psf/codeofconduct/
