On Fri, Aug 14, 2020 at 4:38 PM Caleb Donovick <donov...@cs.stanford.edu> wrote:
> My own personal use for this would be for generating anonymous protocols > and dataclasses: > > class T(Protocol): > x: int > y: str > # with some abuse of notation obviously these would generate unique > typesassert T == Struct[x=int, y=str] > # similarly @dataclassclass S: > x: int > y: str > assert S == Struct[x=int, y=str] > > I often want to create such types “on the fly” without needing to put a > name on them. > > Now as I don’t need mixed keyword / positional arguments I can achieve > this with: > > # K = dict > Struct[K(x=int, y=str)] > > But that costs 3 more keystrokes and is certainly less beautiful. > > While I would not personally use this I think a real killer app would be > slicing named axis, as the slice syntax is exclusive to geitem and hence > can not leverage the dict trick. > To me, the main weakness here is that you couldn't move forward with this unless you also got the various static type checkers on board. But I don't think those care much about this use case (an inline notation for what you can already do with a class definition and annotations). And without static checking this isn't going to be very popular. If and when we have `__getitem__` with keyword args we can start thinking about how to best leverage it in type annotations -- I would assume that describing axes of objects like numpy arrays would be the first use case. -- --Guido van Rossum (python.org/~guido) *Pronouns: he/him **(why is my pronoun here?)* <http://feministing.com/2015/02/03/how-using-they-as-a-singular-pronoun-can-change-the-world/>
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