Converting Python code to C/C++

[Couper, Tim T]

Your prof. may find this thread of interest

http://mail.python.org/pipermail/python-list/2000-June/039779.html

My experience is that developers who know C and C++ can be productive in
less than 1 week in python, and find it liberating, and educational, to
do so. And at the same time they will have added a second language to
their toolbox. As Kurt points out, learning C/C++ takes considerably
longer (weeks/months to attain a level of competence). 

Python is now used in a number of universities as the language in which
to teach comp sci undergraduate courses (I know of Leeds, & MIT),
biomathematics, and my daughter just finished her PhD in speech and
language processing at Edinburgh .. using python and Matplotlib .. as
the extensive C/C++ libraries in that infomatics world are wrapped in
python - and the MSc Comp Sci course has replaced Java as the language
for teaching with Python.

Dr Tim Couper 

-----Original Message-----
From: python-list-bounces+tim.couper=standardbank.com at python.org
[mailto:python-list-bounces+tim.couper=standardbank.com at python.org] On
Behalf Of Kurt Smith
Sent: 23 June 2009 16:50
Cc: python-list at python.org
Subject: Re: Converting Python code to C/C++

On Mon, Jun 22, 2009 at 9:49 PM, Andras
Pikler<Andras.Pikler at students.olin.edu> wrote:
> Hi!
>
>
>
> Short: I need to turn a Python program that I (mostly) wrote into C 
> code, and I am at a loss.
>
>
>
> Long: I'm doing research/programming for a professor, and we are 
> working with MIDI files (a type of simple music file). The research 
> deals with generating variations from a musical melody; currently, my 
> Python code uses a Python midi package I found online to read the 
> notes in question from a midi file, about 350 lines of my own code to 
> generate a variation based on these notes and the professor's 
> algorithms, and finally the package again to write the new melody to
another midi file.
>
>
>
> Now, my professor would like to have this exact code in C/C++, as she 
> believes C is more compatible with MATLAB, and wants the code to be 
> available in multiple languages in case a programmer works for her in 
> the future who knows C but not Python. While I know a tiny bit of C 
> (emphasis on the tiny), I would much prefer if there were some sort of

> automatic compiler I could use to turn my Python code into C than 
> taking a week or two or three to learn the minimum I need about C, 
> find a way to access MIDI files in it, and rewrite all of my code.
>
>
>
> After some googling, I found and tried Shedskin, but it doesn't work, 
> as the Python midi package I'm using uses modules which Shedskin does
not support.
> Otherwise, I haven't found much. Is there anything out there to help 
> me do this? If not, from anyone who has experience in this regard, how

> daunting should I expect this to be?


Taking on C from a cold start and being able to handle the ins and outs
of interfacing with Python isn't something that's feasible in 'two or
three weeks'.  Here are a couple of options -- take 'em or leave 'em:

1) Put the code in Cython: http://www.cython.org/  (full disclosure:
I'm doing a GSoC project with Cython).  It will convert pretty much any
python code into C code (even closures are supported in the most recent
version, I think), and the C code can then be compiled into an extension
module.

The only problem with the above is the C code isn't, at first blush,
easy to read.  Nor is it supposed to be changed by the user.  So that
leads us to option...

2) Write the core functionality in C yourself, and then wrap those C
functions in Cython.  You'll want to take a look at the documentation:

http://docs.cython.org/

and, more specifically on wrapping C code:

http://docs.cython.org/docs/external_C_code.html

I don't think you'll be able to avoid learning C, though.

Kurt
--
http://mail.python.org/mailman/listinfo/python-list


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