On Sat, Oct 31, 2020 at 21:48 Dan Stromberg <drsali...@gmail.com> wrote:
> > On Sat, Oct 31, 2020 at 9:37 PM Guido van Rossum <gu...@python.org> wrote: > >> >> I think this over-stresses the notion that users might want to override >> the comparison operator to be used. We only have two operators that make >> sense in this context, 'is' and '==', and really, for almost everything you >> want to do, '==' is the appropriate operator. (There is a small trickle of >> bugs caused by people inappropriately using e.g. `if x is 1` instead of `if >> x == 1`, suggesting that if anything, there is too much freedom here.) The >> big exception is `None`, where you basically always want to use `is`, which >> is what PEP 634 does. >> > FWIW, there's an additional exception: > sentinel = object() > > if var is sentinel: > > I use this idiom from time to time - instead of None. > You can just write ‘case sentinel’, since object’s == operator uses identity anyway. > -- --Guido (mobile)
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