2018年6月21日(木) 1:17 Antoine Pitrou <solipsis@pitrou.net>:
On Wed, 20 Jun 2018 18:09:00 +0200
Victor Stinner <vstinner@redhat.com> wrote:
>
> > If we can't at Python 3.7, I think we should do it at 3.8. 
>
> What's the rationale to make it public in 3.7? Can't it wait for 3.8?
> The new PEPs target 3.8 anyway, no?
>
> IMHO it's too late for 3.7.

Agreed with Victor.  Also Jeroen's work might lead us to change the
protocol for better flexibility or performance.

Unless libraries are written with METH_FASTCALL (or using Cython), tp_ccall can't have any gain for 3rd party functions written in C.

In other words, if many libraries start supporting FASTCALL, tp_ccall will have more gain at the time when Python 3.8 is released.

  Let's not make it a
public API too early.

Ok.

Even though it's private at 3.7, extension authors can start using it at their risk if we decide METH_FASTCALL is public in 3.8 without any change from 3.7.