Since Cython is a common consumer of this C API, can somone please dig
into Cython to see exactly what it needs in terms of API? How does
Cython create all arguments of the __Pyx_PyCode_New() macro? Does it
copy an existing function to only override some fields, something like
CodeType.replace(field=new_value)?
If possible, I would prefer that Cython only uses the *public* C API.
Otherwise, it will be very likely that Cython will break at every
single Python release. Cython has a small team to maintain the code
base, whereas CPython evolves much faster with a larger team.
Victor
I don't claim knowledge of Cython internals, but the two places it appears to call it's __Pyx_PyCode_New macro are:
and
it'd be best to loop in Cython maintainers for more of an idea of Cython's intents and needs with PyCode_New APIs. I've cc'd
cython-devel@python.org.
-Greg
On Tue, Aug 17, 2021 at 8:51 AM Gregory P. Smith <greg@krypto.org> wrote:
>
> Doing a search of a huge codebase (work), the predominant user of PyCode_New* APIs appears to be checked in Cython generated code (in all sorts of third_party OSS projects). It's in the boilerplate that Cython extensions make use of via it's __Pyx_PyCode_New macro. https://github.com/cython/cython/blob/master/Cython/Utility/ModuleSetupCode.c#L470
>
> I saw very few non-Cython uses. There are some, but at a very quick first glance they appear simple - easy enough to reach out to the projects with a PR to update their code.
>
> The Cython use will require people to upgrade Cython and regenerate their code before they can use the Python version that changes these. That is not an uncommon thing for Cython. It's unfortunate that many projects on ship generated sources rather than use Cython at build time, but that isn't _our_ problem to solve. The more often we change internal APIs that things depend on, the more people will move their projects towards doing the right thing with regards to either not using said APIs or rerunning an up to date code generator as part of their build instead of checking in generated unstable API using sources.
>
> -gps
>
>
> On Mon, Aug 16, 2021 at 8:04 PM Guido van Rossum <guido@python.org> wrote:
>>
>> On Mon, Aug 16, 2021 at 4:44 PM Nick Coghlan <ncoghlan@gmail.com> wrote:
>>>
>>> [...]
>>> A cloning-with-replacement API that accepted the base code object and the "safe to modify" fields could be a good complement to the API deprecation proposal.
>>
>>
>> Yes (I forgot to mention that).
>>
>>>
>>> Moving actual "from scratch" code object creation behind the Py_BUILD_CORE guard with an underscore prefix on the name would also make sense, since it defines a key piece of the compiler/interpreter boundary.
>>
>>
>> Yeah, we have _PyCode_New() for that.
>>
>>>
>>> Cheers,
>>> Nick.
>>>
>>> P.S. Noting an idea that won't work, in case anyone else reading the thread was thinking the same thing: a "PyType_FromSpec" style API won't help here, as the issue is that the compiler is now doing more work up front and recording that extra info in the code object for the interpreter to use. There is no way to synthesise that info if it isn't passed to the constructor, as it isn't intrinsically recorded in the opcode sequence.
>>
>>
>> That's the API style that _PyCode_New() uses (thanks to Eric who IIRC pushed for this and implemented it). You gave me an idea now: the C equivalent to .replace() could use the same input structure; one can leave fields NULL that should be copied from the original unmodified.
>>
>> --
>> --Guido van Rossum (python.org/~guido)
>> Pronouns: he/him (why is my pronoun here?)
>> _______________________________________________
>> Python-Dev mailing list -- python-dev@python.org
>> To unsubscribe send an email to python-dev-leave@python.org
>> https://mail.python.org/mailman3/lists/python-dev.python.org/
>> Message archived at https://mail.python.org/archives/list/python-dev@python.org/message/NWYMCDAMS4YRJ7ESXNWQ6MIBSRAZEXEM/
>> Code of Conduct: http://python.org/psf/codeofconduct/
>
> _______________________________________________
> Python-Dev mailing list -- python-dev@python.org
> To unsubscribe send an email to python-dev-leave@python.org
> https://mail.python.org/mailman3/lists/python-dev.python.org/
> Message archived at https://mail.python.org/archives/list/python-dev@python.org/message/67DMIW7NQE6M6LEPLANXKZQEFOFVPBBL/
> Code of Conduct: http://python.org/psf/codeofconduct/
--
Night gathers, and now my watch begins. It shall not end until my death.