[Python-Dev] PEP 575, 576, 579 and 580

[INADA Naoki]

> IMO, mailing lists are a terrible way to do software design, but a good
> way to gather requirements as it makes less likely that someone will be
> forgotten.
>

Agreed.  There are several topics we should discuss for these PEPs.
Mailing list is hard to follow.

Can we have other communication channel?  Dedicated Github repository?
zulip? or discuss.python.org?

> So, let us gather the requirements for a new calling API.
>
> Here are my starting suggestions:
>
> 1. The new API should be fully backwards compatible and shouldn't break
> the ABI

Agreed.  We have chance to break ABI/API slightly at Python 4, although
breakage should be very small compared with Python 3.

Until then, we should keep backward compatibility as possible.

> 2. The new API should be used internally so that 3rd party extensions
> are not second class citizens in term of call performance.

These PEPs proposes new public protocol which can be implemented
by 3rd party extensions, especially Cython.
In this meaning, it's not used only *internally*.

> 3. The new API should not prevent 3rd party extensions having full
> introspection capabilities, supporting keyword arguments or another
> feature supported by Python functions.

OK.

> 4. The implementation should not exceed D lines of code delta and T
> lines of code in total size. I would suggest +200 and 1000 for D and T
> respectively (or is that too restrictive?).

Hmm, I think this should be considered as (Frequency * Value) / (Complexity).
Especially, if PEP 580 can removes 2000 lines of code, T>1000 seems OK.

> 5. It should speed up CPython for the standard benchmark suite.

I think it's impossible in short term.  We have specialized optimization
(FASTCALL and LOAD_METHOD/CALL_METHOD) already.
These optimization makes simple method calls 30% faster.
These PEPs makes 3rd party callable types can utilize these optimization.

> 6. It should be understandable.
>

OK.
While main audience is Cython, C extension writer should be able to use
new protocols by handwritten extension.

> What am I missing? Comments from the maintainers of Cython and other
> similar tools would be appreciated.
>
> Cheers,
> Mark.


-- 
INADA Naoki  <songofacandy at gmail.com>