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To: python-list@python.org
From: Sturla Molden <sturla.molden@gmail.com>
Subject: Re: Python, C++ interaction
Date: Wed, 3 Dec 2014 10:15:41 +0000 (UTC)
References: <547EC9E2.8070502@perfect-kreim.de>
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Xref: csiph.com comp.lang.python:81849

Cython is nearly always the answer to scientific computing in Python,
including wrapping C++.

Sturla


Michael Kreim <michael@perfect-kreim.de> wrote:
> Hi,
> 
> we are working on a small scientific program that helps us in developing 
> and testing of new numerical methods for a certain type of biochemical 
> problems. I spare you the math ;-)
> 
> We code our new methods in Python and compare them with the existing 
> methods. Unfortunately, these existing methods are quite slow and need a 
> lot of runtime. Therefor we implemented them in C++.
> 
> Now, we like to combine these two approaches. So we can develop a new 
> method in Python and compare it easily with the results from the C++ 
> functions.
> 
> I did some googleing on extending Python by C++ code but I did not find 
> something that satisfies me. I gave SWIG a try, but several webpages 
> disadvised me of using it. Also my small experiments did not work. Now, 
> I read about ctypes. But as far as I understood it, I have to write a C 
> wrapper for my C++ code and then a Python wrapper for my C code. That 
> seems a little complicated.
> 
> My C++ code is structured as a class that contains several variables and 
> functions. Then everything is compiled as a shared library. I can write 
> things like:
> 
> MyClass.initialvalue = 5;
> MyClass.timestep = 0.1;
> ...
> MyClass.solve();
> 
> I would like to keep this structure in python, but if I understand 
> ctypes correctly I would loose the class approach.
> 
> So after the long writeup I come to my questions:
> 
> What are you using to wrap C++ classes for Python?
> Can you recommend swig? Should I give it another try?
> Did I misunderstood ctypes?
> 
> Also later on in our code development we would like to pass python 
> lambda functions to C++. So far I understood that this seems not to be 
> possible. Do you have any ideas or hints on this topics?
> 
> Thank you very much.
> 
> Cheers,
> 
> Michael