[Python-Dev] C-level calling (was: PEP 575 (Unifying function/method classes) update)

Stefan Behnel stefan_ml at behnel.de
Wed Jun 20 02:00:48 EDT 2018

Victor Stinner schrieb am 19.06.2018 um 16:59:
> 2018-06-19 13:58 GMT+02:00 Jeroen Demeyer <J.Demeyer at ugent.be>:
>> Personally, I think that you are exaggerating these issues.
> I'm not trying to convince you to abandon the idea. I would be happy
> to be able to use FASTCALL in more cases! I just tried to explain why
> I chose to abandon my idea.
> FASTCALL is cute on tiny microbenchmarks, but I'm not sure that having
> spent almost one year on it was worth it :-)

Fastcall is actually nice, also because it has a potential to *simplify*
several things with regard to calling Python objects from C.

Thanks for implementing it, Victor.

Just to add another bit of background on top of the current discussion,
there is an idea around, especially in the scipy/big-data community, (and
I'm not giving any guarantees here that it will lead to a PEP +
implementation, as it depends on people's workload) to design a dedicated C
level calling interface for Python. Think of it as similar to the buffer
interface, but for calling arbitrary C functions by bypassing the Python
call interface entirely. Objects that wrap some kind of C function (and
there are tons of them in the CPython world) would gain C signature meta
data, maybe even for overloaded signatures, and C code that wants to call
them could validate that meta data and call them as native C calls.

But that is a rather big project to undertake, and I consider Jeroen's new
PEP also a first step in that direction.


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