Thanks for your contribution to Python, but I wonder if this is really necessary. In Python, if a function doesn't explicitly return something else, it always implicitly returns None. We generally don't document this because if we did so everywhere, the documentation would be pretty noisy. Note that this is different from functions which explicitly return None for reasons of their API design.

I do agree that it would be inappropriate to do this everywhere, but I don't think it would hurt anything to mention it for print() specifically (the scope of this PR), short of concern that it's a slippery-slope that leads to "do it for everything" PRs.

I've certainly seen beginners do something = print(...) enough times that when this came up again in #python on Libera IRC I thought I would open an issue on the user's behalf.

Yes it's a slippery slope, but it's also confusing. A user might question "why does the print documentation mention this both other functions don't?" As I mentioned in the bug comment, I think it does users a better service to explain how Python return values work.

I am also torn. print is probably used a lot, and used early in learning. If this page was not library/functions but the tutorial, I would just add the mention!

Two ideas / questions for the PR author:

• Does the tutorial mention the implicit return of None? If not, should it?
• Would it help to mention it at the top of this file (too)? (maybe not if people don’t start at the top but use a link that jumps to specific function)

This reminds me of https://bugs.python.org/issue42571 where someone did not know what * and / meant in function signatures, and also did not know to search for it. (BTW to me this shows that Python is right to generally prefer words over symbols, see recent lambda vs => discussion)

Maybe these two issues can be tackled with some text with links at the top of this doc file.

Maybe these two issues can be tackled with some text with links at the top of this doc file.

This occurs to me too. Rather than a one-off, providing information on how Python return values (and maybe also documented function signatures) seems more like teaching someone how to fish rather than giving them a fish.

Does the tutorial mention the implicit return of None? If not, should it?

The tutorial does mention it...in a fairly roundabout way. Viewing § 4.7 Defining Functions at 1920x1080 on a laptop screen, it's the second page of that section.

Perhaps this PR/issue can be closed in favor of making this property of functions more obvious in the documentation.

Perhaps this PR/issue can be closed in favor of making this property of functions more obvious in the documentation.

+1

Personally I think it would be better to have "noisy" documentation that specifies the return value of every single documented function, even if many of them are none. It doesn't take that much space to write "Returns None". Explicit is better than implicit. :-)