[Python-Dev] PEP 399: Pure Python/C Accelerator Module Compatibiilty Requirements
stefan_ml at behnel.de
Tue Apr 19 12:01:44 CEST 2011
Nick Coghlan, 19.04.2011 10:57:
> On Tue, Apr 19, 2011 at 3:06 PM, Stefan Behnel wrote:
>> I think this social problem of the PEP can only be solved if the CPython
>> project stops doing the major share of the stdlib maintenance, thus freeing
>> its own developer capacities to focus on CPython related improvements and
>> optimisations, just like the other implementations currently do. I'm not
>> sure we want that at this point.
> We've made a start on that aspect by granting CPython access to
> several of the core developers on the other VMs. The idea being that
> they can update the pure Python versions of modules directly rather
> than having to wait for one of us to do it on their behalf.
> Of course, as Maciej pointed out, that is currently hindered by the
> fact that the other VMs aren't targeting 3.3 yet, and that's where the
> main CPython development is happening.
A related question is: when other Python VM projects try to port a given C
module, would they actually invest the time to write a pure Python version
that may or may not run within acceptable performance bounds for them, or
would they prefer saving time by writing only a native implementation
directly for their VM for performance reasons? Maybe both, maybe not. If
they end up writing a native version after prototyping in Python, is the
prototype worth including in the shared stdlib, even if its performance is
completely unacceptable for everyone? Or, if they write a partial module
and implement another part of it natively, would the incomplete
implementation qualify as a valid addition to the shared stdlib?
Implementing a 100% compatible and "fast enough" Python version of a module
is actually a rather time consuming task. I think we are expecting some
altruism here that is easily sacrificed for time constraints, in any of the
Python VM projects. CPython is just in the unlucky position of representing
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