[Python-Dev] cpython: Add Py_RETURN_NOTIMPLEMENTED macro. Fixes #12724.

[Barry Warsaw]

On Aug 16, 2011, at 08:32 AM, Nick Coghlan wrote:

>Indeed, this entire discussion was started by the extension of the
>Py_RETURN_NONE idiom to also adopt Py_RETURN_NOTIMPLEMENTED.
>
>If the idiom is to be extended at all, why stop there? Why not cover
>the Py_RETURN_TRUE and Py_RETURN_FALSE cases as well?
>
>Or, we can add exactly one new macro that covers all 3 cases, and
>others besides. I haven't encountered any complaints about people
>failing to understand the difference between "return Py_None;" and
>"Py_RETURN_NONE;" and see no major reason why "return x;" vs
>"Py_RETURN(x);" would be significantly more confusing.
>
>Based on this thread, there are actually two options I'd be fine with:
>1. Just revert it and leave Py_RETURN_NONE as a special snowflake
>2. Properly generalise the incref-and-return idiom via a Py_RETURN macro
>
>Incrementally increasing complexity by adding a second instance of the
>dedicated macro approach is precisely what we *shouldn't* be doing.

My problem with Py_RETURN(x) is that it's not clear that it also does an
incref, and without that, I think it's *more* confusing to use rather than
just writing it out explicitly, Py_RETURN_NONE's historic existence
notwithstanding.

So I'd opt for #1, unless we can agree on a better color for the bikeshed.

-Barry