Robert Bradshaw, 22.03.2011 08:14:
On Mon, Mar 21, 2011 at 11:10 PM, Stefan Behnel wrote:
there seems to be quite some interest in a project to get parts of CPython
and specifically its stdlib rewritten in Cython. [...]
In short, we have strong supporters, but Guido has understandable doubts
against a new (and quite large) dependency and potential semantic
deviations.
Reading the list, I think others on the list overestimate the semantic
differences. Mostly we're talking about things like is vs. equality
for floating point numbers and tracebacks (at least for un-annotated
code).
I think so too, that's what I tried to make clearer with my last reply. I
think Cython is actually pretty close to Python semantics overall, and
almost all deviations are explicitly triggered by type annotations in the code.
It's a valid point that Cython is still under such active development.
Absolutely. Eventually, we'd have to settle on a specific version for the
compiler used in the stdlib, and support that at least as long as the
CPython version that uses it.
It would be helpful to get support from the side of external distributors
that use Cython already, e.g. Sage, Enthought/SciPy, ActiveState, etc. If
they agreed to test the Cython generated stdlib modules in their
distributions, we could get user feedback that would allow python-dev to
take a well founded decision.
Do we have any volunteers for trying this out? Both on the side of
distributors and implementors?
I think Sage might be willing to give it a try. I'll ask tomorrow as
part of a talk I'm giving.
Cool.
Note that due to the way Python's import
mechanism works, it would be easy (as a first pass) to make a
"cythonize this Python install" which would just compile (a subset of)
the .py files and drop .so files next to them. This would require no
messing with the Python build system or distribution, easy to test and
benchmark, and be easy to clean up.
Sure, I implemented that in pyximport ages ago, when Cython was really far
from being able to compile much in the stdlib. We should totally give it a
try once Vitja's branch is in shape.
At the current state of affairs, the implementation could still be financed
by a Python backed GSoC project, although it would be cool if more users
could just step up and simply try to compile and optimise stdlib modules
(preferably without major changes to the code). It's certainly a great way
to show off your Cython skills :). I gave it a try with difflib and it
turned out to be quite easy.
http://blog.behnel.de/index.php?p=155
Reimplementing existing C modules in Cython might, however, be more
interesting for python-dev, but also be a larger undertaking. So a GSoC
might be worth running on that.
I think that's a great idea. Would you be willing to mentor such a project.
As usual, I'm not sure I'll have the time, but if no-one else steps up, I'd
consider it.
Stefan
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