Custom double star operator for a class?

Question

How does one implement custom double star operator (**) for unpacking, similar to how __iter__ works with single star operator (*)?

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Answer 1

As @ShadowRanger says, implement Mapping. Here's an example:

from collections.abc import Mapping

class Foo(Mapping):
    def __iter__(self):
        yield "a"
        yield "b"

    def __len__(self):
        return 2

    def __getitem__(self, item):
        return ord(item)

f = Foo()

print(*f)
print(dict(**f))

The program outputs:

a b
{'a': 97, 'b': 98}