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()).
