[Python-Dev] [PEP 576/580] Comparing PEP 576 and 580

INADA Naoki songofacandy at gmail.com
Tue Jul 31 05:12:11 EDT 2018

On Tue, Jul 31, 2018 at 5:46 PM Jeroen Demeyer <J.Demeyer at ugent.be> wrote:
> On 2018-07-31 09:36, INADA Naoki wrote:
> > I want to see PoC of direct C calling.
> To be honest, there is no implementation plan for this yet. I know that
> several people want this feature, so it makes sense to think about it.

Yes.  It will be the strong benefit of PEP 580.

> For me personally, the main open problem is how to deal with arguments
> which may be passed both as Python object or as native C type. For
> example, when doing a function call like f(1,2,3), it may happen that
> the first argument is really a Python object (so it should be passed as
> Python int) but that the other two arguments are C integers.

I don't think it's the main point...
At first time, we can just skip direct calling path and use normal Python call.

> > And I think PoC can be implemented without waiting PEP 580.
> For one particular class (say CyFunction), yes. But this feature would
> be particularly useful for calling between different kinds of C code,
> for example between Numba and CPython built-ins, or between Pythran and
> Cython, ...
> That is why I think it should be implemented as an extension of PEP 580.

Of course,  finally it can be implemented based on PEP 580.

But I said "Proof of Concept".  Optimize only Cython-to-Cython case is enough
for "Proof of Concept".  PoC makes it easy to discuss concrete API design for
cross implementation call.

> Anyway, this is a different subject that we should not mix in the
> discussion about PEP 580 (that is also why I am replying to this
> specific point separately).

For me, this is the most important benefit of PEP 580.  I can't split
it from PEP 580.

And I didn't say PoC is needed *before* accepting or discussing PEP 580.
I just meant PoC can be implemented without waiting PEP 580 accepted,
and I want see it early.

Any PEP won't be accepted in few month, because we don't have flow to
accept PEPs for now.
And I think Victor and Serhiy are key person about these PEPs, but I don't know
when they have enough time to review / discuss / make decision about these PEPs.

So it's worthless that waiting PEP accepted before start PoC.

INADA Naoki  <songofacandy at gmail.com>

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