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

[Guido van Rossum]

On Mon, Aug 15, 2011 at 3:43 PM, Barry Warsaw <barry at python.org> wrote:
> 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.

I dunno; if it *didn't* do an INCREF it would be a pretty pointless
macro (just expanding to "return x") and I like reducing the clutter
of a very common idiom. So I favor #2.

-- 
--Guido van Rossum (python.org/~guido)