Mailman 3 January 2015 - cython-devel

Re: [Cython] Bringing Cython and PyPy closer together
by Stefan Behnel March 29, 2015

March 29, 2015

[copied here from PyPy mailing list] Stefan Behnel, 15.02.2012 12:32: > The current state of the discussion seems to be that PyPy provides ways to > talk to C code, but nothing as complete as CPython's C-API in the sense > that it allows efficient two-way communication between C code and Python > objects. Thus, we need to either improve this or look for alternatives. > > In order to get us more focussed on what can be done and what the > implications are, so that we may eventually be able to decide what should > be done, I started a Wiki page for a PyPy backend CEP (Cython Enhancement > Proposal). > > http://wiki.cython.org/enhancements/pypy The discussion so far makes me rather certain that the most promising short-term solution is to make Cython generate C code that PyPy's cpyext can handle. This should get us a rather broad set of running code somewhat quickly, while requiring the least design-from-scratch type of work in a direction that does not yet allow us to see if it will really make existing code work or not. On top of the basic cpyext interface, it should then be easy to implement obvious optimisations like native C level calls to Cython wrapped functions from PyPy (and potentially also the other direction) and otherwise avoid boxing/unboxing where unnecessary, e.g. for builtins. After all, it all boils down to native code at some point and I'm sure there are various ways to exploit that. Also, going this route will help both projects to get to know each other better. I think that's a required basis if we really aim for designing a more high-level interface at some point. The first steps I see are: - get Cython's test suite to run on PyPy - analyse the failing tests and decide how to fix them - adapt the Cython generated C code accordingly, special casing for PyPy where required Here is a "getting started" guide that tells you how testing works in Cython: http://wiki.cython.org/HackerGuide Once we have the test suite runnable, we can set up a PyPy instance on our CI server to get feed-back on any advances. https://sage.math.washington.edu:8091/hudson/ So, any volunteers or otherwise interested parties to help in getting this to work? Anyone in for financial support? Stefan

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Compilation failes if a class member is named "INFINITY"
by Michael Feb. 5, 2015

Feb. 5, 2015

Hello, if I try to compile the following minimal example: cdef class Test: cdef readonly int INFINITY cython does not complain but gcc refuses with an error message: In file included from /usr/include/math.h:38:0, from /usr/include/python2.7/pyport.h:325, from /usr/include/python2.7/Python.h:58, from testinf.c:16: testinf.c:433:7: error: field '__builtin_inff' declared as a function int INFINITY; ^ testinf.c: In function '__pyx_pf_7testinf_4Test_8INFINITY___get__': testinf.c:569:50: error: expected identifier before '(' token __pyx_t_1 = __Pyx_PyInt_From_int(__pyx_v_self->INFINITY); if (unlikely(!__pyx_t_1)) {__pyx_filename = __pyx_f[0]; __pyx_lineno = 10; __pyx_clineno = __LINE__; goto __pyx_L1_error;} ^ Apparently the name "INFINITY" is handled wrongly; any other variable name seems to be fine. Regards, Michael

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IPython with Cython support on Android
by Apps Embedded Feb. 3, 2015

Feb. 3, 2015

Hi, We have developped an android app which makes it possible to use the IPython shell through Android. https://play.google.com/store/apps/details?id=com.appsopensource.labpy https://play.google.com/store/apps/details?id=com.appsopensource.labpypremi… We decided then to add the Cython extension to speed up script execution through the notebook for instance. Our app bundle is covered by the Gnu GPL v3 licence. Cython is covered by the Apache Licence version 2.0 which is compatible with the Gnu GPL v3 licence. Our question concerns the Pyrex licence on which Cython is based. It is on OSI approved licence. >From your point of view, is the Pyrex licence GPL v3 compatible ? Thanks for your help. Apps Embedded team.

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bug in typed memoryviews (memoryviewslice)
by Richard Hansen Jan. 30, 2015

Jan. 30, 2015

Hi all, If I create foo.pyx with the following contents: cpdef object foo(): cdef unsigned char[:] s = <bytearray><unsigned char *>"012345" return s I notice the following behavior: $ python -c ' import foo m=foo.foo() print repr(memoryview(m.base).tobytes()) print repr(memoryview(m).tobytes()) ' '012345' '123450' Notice how the bytes are printed in the wrong order unless I use the original buffer object via the typed memoryview object's base attribute. -Richard

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Cython 0.22 beta
by Robert Bradshaw Jan. 22, 2015

Jan. 22, 2015

I've posted a beta for Cython 0.22, please try it out and report any problems (and successes) you encounter. http://cython.org/release/Cython-0.22.beta0.tar.gz

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Variable Step Value
by Favian Contreras Jan. 22, 2015

Jan. 22, 2015

Hey all, I am having some trouble figuring out how to pass in an extra IfStatNode in Optimize.py, to the code generation stage (see 1st commented block). I am also having trouble getting the temp variable of the iteration variable, so that I can adjust the temp to be the value that would be in index (see the 2nd comment block), before the iteration variable gets set. As of now I get the correct number of steps, as long as the step value is not 0. I've tried making these fields "StatListNode"s, but that gives a messy error. Any suggestions for how to handle these 2 problems? commit: https://github.com/BigFav/cython/commit/015440543b051168cb34441a6a8494b6fa5… Thanks, Favian Contreras

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Cython 0.22.alpha
by Robert Bradshaw Jan. 19, 2015

Jan. 19, 2015

It's been too long since we've done a release, and the features have started to pile up, so I'm getting the ball rolling with 0.22.alpha0. I've uploaded a tarball to http://cython.org/release/Cython-0.22.alpha0.tar.gz; you can also get it from github. Let me know what breaks/works for you, and if there's anything you think should get in. If feedback is good I'll be cutting a beta (to the users list) next week. - Robert

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Cythonize silently ignores nonexistent files
by Kevin Norris Jan. 9, 2015

Jan. 9, 2015

Is this behavior intentional? >>> from Cython.Build import cythonize >>> cythonize('/this/file/doesnt/exist.pyx') [] It would be *really* nice if Cython would raise an exception (or something) in this case. I just spent 20 minutes trying to puzzle out Cython/Setuptools compatibility when the actual problem was staring me in the face. -- Kevin Norris

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