Bdtjtk

Python has the 2 operators * and ** for packing and unpacking of parameters, e.g.

print(*[1,2,3,4])

or

def test(*args, **kwargs):

    ...

There is no mention of these operators in the operator module, and there is no way to overwrite them.
For example, this could be a thing:

class Test(object):



    def __init__(self):

        self.a = 5

        self.b = 10



    def __starstar__(self):

        # Not to be confused with __pow__!

        # Should return something that can be unpacked by the default ** operator

       return {"a": self.a, "b": self.b}



def print_a_b(a, b):

    print(f"a is {a} and b is {b}")



print_a_b(**Test())

# Should be unpacked into a and b parameters

# and print "a is 5 and b is 10"

It kind of works with the * operator and iterables:

class Test2(object):



    def __iter__(self):

        yield from range(10)



print(*Test2())

# prints "0 1 2 3 4 5 6 7 8 9"

I understand that we can not use ** and __getitem__, since we don't know the items that may be present. But why is there no operator that can be overwritten for **, and why is there no operator in the operator module for * and **?

One reason I could think of is that this would contribute to coupling in the wrong direction between classes, i.e. Test now implicitly knows about the signature of print_a_b.

A better use case might be a Config class that does some additional setup and can then be passed to another function, e.g run(**Config()).