[Python-Dev] PEP 399: Pure Python/C Accelerator Module Compatibiilty Requirements

[Michael Foord]

On 05/04/2011 20:57, Raymond Hettinger wrote:
> [snip...]
> [Brett]
>> (sorry, Raymond, for picking on heapq, but is
>> was what bit the PyPy people most recently =).
> No worries, it wasn't even my code.  Someone
> donated it.  The was a discusion on python-dev
> and collective agreement to allow it to have
> semantic differences that would let it run faster.
> IIRC, the final call was made by Uncle Timmy.
>

The major problem that pypy had with heapq, aside from semantic 
differences, was (is?) that if you run the tests against the pure-Python 
version (without the C accelerator) then tests *fail*. This means they 
have to patch the CPython tests in order to be able to use the pure 
Python version.

Ensuring that tests run against both (even if there are some unavoidable 
differences like exception types with the tests allowing for both or 
skipping some tests) would at least prevent this happening.

All the best,

Michael

> That being said, I would like to see a broader set
> of examples rather rather than extrapolating from
> a single piece 7+ year-old code.  It is purely
> algorithmic, so it really just represents the
> simplest case.  It would be much more interesting
> to discuss something what should be done with
> future C implementations for threading, decimal,
> OrderedDict, or some existing non-trivial C
> accelerators like that for JSON or XML.
>
> Brett, thanks for bringing the issue up.
> I've been bugged for a good while about
> issues like overbroad use of the concrete C API.
>
>
> Raymond
>
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