On 2021-09-30 6:08 p.m., Chris Angelico wrote:
I still think that your use of LookupError is confusing the issue somewhat, partly because it's a base class rather than something that's ever raised per se.
If you were using a custom exception type, how likely is it that that exception would be raised during the unpacking? Under what situations would this happen, and might it actually be an intended way for that property value to say "actually, heh... I don't exist"? Because the logical way to spell that would be "raise PropertyNotFoundError" (or whatever you use instead of LookupError). IOW, bubbling is exactly correct. You still haven't explained how that isn't the case.
Bubbling is correct, but it doesn't deny that explicit is better than implicit. Rust's `?` operator (generally referred to as "try" by the devs) has a lot that can be learned from, here. (Not to say it would be the appropriate solution for Python.)