What does * mean in a function definition?

Question

I have code like this

def my_pow(x=3, *, y=2):
    return x**y
my_pow(4,4)

I know what *args and **kwargs mean, but have no idea what * means between positional arguments.

Why my_pow(4,4) doesn't work? Whereas all variants below do.

my_pow(4,y = 4)
my_pow(x = 4)
my_pow(y = 4)
my_pow(4)

score 1 · Answer 1 · edited Sep 04 '21 at 16:05

1

* marks that arguments after it in the function's definition are keyword-only. It was introduced in Python 3.0.

The reason pow(4, 4) does not work is because of that symbol. Only pow(x=4, y=4) or pow(4, y=4) will work.

edited Sep 04 '21 at 16:05

Alex Waygood

answered Sep 04 '21 at 15:36

BoobyTrap

1

``*`` was not introduced in Python 3.8. You might be thinking of ``/``. – MisterMiyagi Sep 04 '21 at 15:38
@MisterMiyagi True, it was introduced in Python 3.0. I'll edit the answer so it doesn't mislead. – BoobyTrap Sep 04 '21 at 15:39

1 Answers1