This has been bouncing around in my head for a while regarding the requisite keys() method on mappings:
How come the ** unpacking operator, a built-in language feature, relies on a non-dunder to operate? To me, I mean to say, requiring that classes implement keys() – a method whose name is totally undistinguished – in order to conform to the mapping protocol feels like a design running counter to Python's norm of using dunders for everything "hidden". I am not sure if it feels dirty to anybody else, however. Interestingly, the docs already say <https://docs.python.org/3/reference/datamodel.html#object.__iter__> that *[f]or mappings, [__iter__()] should iterate over the keys of the container*, but it of course is not enforced in any way at present. So, then — how about enforcing it? Should __iter__(), for the reasons above, replace the current purpose of keys() in mappings? I'm not properly equipped at the moment to mess around with CPython (sorry), but I assume at a minimum this would entail either replacing all instances of PyMapping_Keys() with PyObject_GetIter() or alternatively changing PyMapping_Keys() to call the latter. Does it sound like a reasonable change overall? Eli
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