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

[Nick Coghlan]

On Mon, Aug 15, 2011 at 11:59 PM, Antoine Pitrou <solipsis at pitrou.net> wrote:
> On Mon, 15 Aug 2011 09:49:43 -0400
> Barry Warsaw <barry at python.org> wrote:
>> I can see the small value in the convenience, but I tend to agree with Raymond
>> here.  I think we have to be careful about not descending into macro
>> obfuscation world.
>
> How is Py_RETURN(Py_NotImplemented) more obfuscated than
> Py_RETURN_NOTIMPLEMENTED ???

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.

Cheers,
Nick.

-- 
Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia