> I don't know how to interpret these examples. What's Protocol and where does it come from? What's Struct?
`Protocol` comes from `typing` `Struct` is my own class which generates anonymous dataclasses and protocols as you gathered (unfortunately I currently have two versions one for building the protocol and one for building the dataclass but thats because of stupid engineering requirements). On Fri, Aug 14, 2020 at 11:14 PM Steven D'Aprano <st...@pearwood.info> wrote: > On Fri, Aug 14, 2020 at 04:07:33PM -0700, Caleb Donovick 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] > > I don't know how to interpret these examples. What's Protocol and where > does it come from? What's Struct? > > As I recall, one of the motivations for re-visiting PEP 472 is to allow > such keyword notation in type hints, so that we could write > > Struct[x=int, y=str] > > in a type hint and have it mean a struct with fields x (an int) and y (a > str). I'm not sure whether that use in type hinting would allow the use > of this Struct to create anonymous classes. I suppose it would, but I'm > not expert enough on type hints to be sure. > > But assuming the two uses are compatible, I must say that having the > same notation for type-hinting a struct and actually creating an > anonymous struct class would be desirable: > > def func(widget:Struct[x=int, y=str]) -> gadget: > pass > > # Later: > MyWidget = Struct[x=int, y=str] > > func(MyWidget(19, 'hello')) > > I really like the look of that, and I think that having the Struct call > use the same subscript notation as the Struct type hint is a plus. > > > > 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. > > This is one of the motivating use-cases of PEP 472. > > > > -- > Steven > _______________________________________________ > 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/HLXSO2KSOB62Z4RI7SA52DHWGCGECATC/ > Code of Conduct: http://python.org/psf/codeofconduct/ >
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