On Wed, Oct 27, 2021 at 5:30 AM Ricky Teachey <ricky@teachey.org> wrote:
> But with function k below, where the b parameter is deferred, you can't get the default b parameter by dynamically unpacking some values; you would have to pass c as a kwd arg:
>
> def k(a, b=>len(a), c=None):
> ...
>
> Seems like it would be- needed? convenient?- to be able to "ask" for the default in a dynamic way... Am I making more of this than is justified?
>
Question: Does it make sense to ask for the default for the second
positional parameter, while passing an actual value for the third? If
it does, then the function needs an API that reflects this. The most
obvious such API is.... what you already described: passing c as a
keyword argument instead. I don't think this is a problem. When you're
looking at positional args, it is only ever the last N that can be
omitted. If it makes sense to pass any combination of arguments, then
they should probably be keyword-only, to clarify this.
Do you have any examples where this isn't the case?
ChrisA
I don't. I only have a niggling feeling that maybe this is a bigger problem than we're giving it credit for.
If I can, I'll try to substantiate it better. Maybe others can better flesh out the concern here if it's valid.
At bottom I guess I'd describe the problem this way: with most APIs, there is a way to PASS SOMETHING that says "give me the default". With this proposed API, we don't have that; the only want to say "give me the default" is to NOT pass something.
I don't KNOW if that's a problem, it just feels like one.
---
Ricky.
"I've never met a Kentucky man who wasn't either thinking about going home or actually going home." - Happy Chandler