On Sat, Feb 18, 2012 at 12:21 PM, Matthew Brett <matthew.br...@gmail.com>wrote:
> Hi. > > On Sat, Feb 18, 2012 at 12:18 AM, Christopher Jordan-Squire > <cjord...@uw.edu> wrote: > > On Fri, Feb 17, 2012 at 11:31 PM, Matthew Brett <matthew.br...@gmail.com> > wrote: > >> Hi, > >> > >> On Fri, Feb 17, 2012 at 10:18 PM, Christopher Jordan-Squire > >> <cjord...@uw.edu> wrote: > >>> On Fri, Feb 17, 2012 at 8:30 PM, Sturla Molden <stu...@molden.no> > wrote: > >>>> > >>>> > >>>> Den 18. feb. 2012 kl. 05:01 skrev Jason Grout < > jason-s...@creativetrax.com>: > >>>> > >>>>> On 2/17/12 9:54 PM, Sturla Molden wrote: > >>>>>> We would have to write a C++ programming tutorial that is based on > Pyton knowledge instead of C knowledge. > >>>>> > >>>>> I personally would love such a thing. It's been a while since I did > >>>>> anything nontrivial on my own in C++. > >>>>> > >>>> > >>>> One example: How do we code multiple return values? > >>>> > >>>> In Python: > >>>> - Return a tuple. > >>>> > >>>> In C: > >>>> - Use pointers (evilness) > >>>> > >>>> In C++: > >>>> - Return a std::tuple, as you would in Python. > >>>> - Use references, as you would in Fortran or Pascal. > >>>> - Use pointers, as you would in C. > >>>> > >>>> C++ textbooks always pick the last... > >>>> > >>>> I would show the first and the second method, and perhaps > intentionally forget the last. > >>>> > >>>> Sturla > >>>> > >> > >>> On the flip side, cython looked pretty...but I didn't get the > >>> performance gains I wanted, and had to spend a lot of time figuring > >>> out if it was cython, needing to add types, buggy support for numpy, > >>> or actually the algorithm. > >> > >> At the time, was the numpy support buggy? I personally haven't had > >> many problems with Cython and numpy. > >> > > > > It's not that the support WAS buggy, it's that it wasn't clear to me > > what was going on and where my performance bottleneck was. Even after > > microbenchmarking with ipython, using timeit and prun, and using the > > cython code visualization tool. Ultimately I don't think it was > > cython, so perhaps my comment was a bit unfair. But it was > > unfortunately difficult to verify that. Of course, as you say, > > diagnosing and solving such issues would become easier to resolve with > > more cython experience. > > > >>> The C files generated by cython were > >>> enormous and difficult to read. They really weren't meant for human > >>> consumption. > >> > >> Yes, it takes some practice to get used to what Cython will do, and > >> how to optimize the output. > >> > >>> As Sturla has said, regardless of the quality of the > >>> current product, it isn't stable. > >> > >> I've personally found it more or less rock solid. Could you say what > >> you mean by "it isn't stable"? > >> > > > > I just meant what Sturla said, nothing more: > > > > "Cython is still 0.16, it is still unfinished. We cannot base NumPy on > > an unfinished compiler." > > Y'all mean, it has a zero at the beginning of the version number and > it is still adding new features? Yes, that is correct, but it seems > more reasonable to me to phrase that as 'active development' rather > than 'unstable', because they take considerable care to be backwards > compatible, have a large automated Cython test suite, and a major > stress-tester in the Sage test suite. > > Matthew, No one in their right mind would build a large performance library using Cython, it just isn't the right tool. For what it was designed for - wrapping existing c code or writing small and simple things close to Python - it does very well, but it was never designed for making core C/C++ libraries and in that role it just gets in the way. Chuck
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