Python C++

Helmut Jarausch jarausch at
Fri Jul 23 11:25:28 CEST 2004

Neal D. Becker wrote:
> Helmut Jarausch wrote:
>>Francois Fernandes wrote:
>>>Is it possible to easyly integrate c++ classes in python?
>>>I don't want to use boost c++.
>>>Does anyone know how to start or where to find documentation for this?
>>I prefer  PyCXX
> Looks interesting.  I want to expose lots of signal processing algorithms
> written in C++ to python.  I want to use std::vector for containers,
> because they are fast.  I need to create python types for
> std::vector<double> and std::vector<std::complex<double>> at minimum.  The
> Python interface doesn't need to know much about these types, just be able
> to create vectors of a given size.
> Would PyCXX be a good choice for this?  Are there any samples of code
> similar to this?

I think, yes. PyCXX allows for use of the STL.
For each type FOO in your module you provide a new_FOO which is called when you
create an object. There you can call any C++ code including class constructors.
PyCXX helps you in filling out these long structs needed for a new type.
It helps with exception handling and reference counting.
I am new to PyCXX myself, but it worked very soon. There is a rather general
example in the Demo directory. I've just copied and modified the code and it
worked like expected - GREAT!  The documentation is not too long but suffucient
and very readable. It does NOT (try to) wrap your C++ classes automatically like
other tools. I prefer this (since I don't have hundreds of classes). One can
easily fully understand what's going on and if something is missing (e.g. I think
conversion of an unsigned int to a Python long int) one can easily add this
feature using calls from the C-API himself.

Helmut Jarausch

Lehrstuhl fuer Numerische Mathematik
RWTH - Aachen University
D 52056 Aachen, Germany

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