[Python-Dev] Let's change to C API!

Nick Coghlan ncoghlan at gmail.com
Sat Aug 4 09:13:55 EDT 2018

On 31 July 2018 at 17:45, Antoine Pitrou <solipsis at pitrou.net> wrote:
> On Tue, 31 Jul 2018 09:27:03 +0200
> Jeroen Demeyer <J.Demeyer at UGent.be> wrote:
>> On 2018-07-31 08:58, Antoine Pitrou wrote:
>> > I think Stefan is right that we
>> > should push people towards Cython and alternatives, rather than direct
>> > use of the C API (which people often fail to use correctly, in my
>> > experience).
>> I know this probably isn't the correct place to bring it up, but I'm
>> sure that CPython itself could benefit from using Cython. For example,
>> most of the C extensions in Modules/ could be written in Cython.
> We don't depend on any third-party Python modules.  Adding a Cython
> dependency for CPython development would be a tough sell.
> Also, a C extension can be built-in (linked statically into the
> interpreter), which I think would be hard to do with Cython.

It'd be *really* nice to at least be able to write some of the C API
tests directly in Cython rather than having to fiddle about with
splitting the test between the regrtest parts that actually define the
test case and the extension module parts that expose the interfaces
that we want to test.

So just as we have a split between the core interpreter components
needed to freeze importlib and the full Python interpreter, it could
be very interesting to have a split between the builtin and extension
modules that are required to bootstrap Cython, and those that can
instead *rely* on Cython as part of their build process.

While actually doing that would likely mean introducing a venv
dependency into the later stages of the build process, we already have
such a dependency for the docs build, and that seems to work OK.


P.S. Note that even though static linking Cython generated modules
with CPython doesn't work right just now, experiments like
suggest that it shouldn't take too many adjustments to the build
process to get it to work by default.

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

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