Access to C functions from a python class using self ?

[Thomas Heller]

christophe grimault <christophe.grimault at novagrid.com> writes:

> Hi there,
> 
> I've been looking to 'ext & emb python', swig, cxx, ... for quite some
> time now, and I still can't figure out how to do the kind of stuff
> explained below...
> 
> 
> I define a class in python, let's say this simple class, just for the
> purpose of discussion :
> 
> 
> class Vector:
>     def __init__(self, x1, x2, x3):
>         self.x1, self.x2, self.x3 = x1, x2, x3
> 
>     def sum(self):
>         return self.x1 + self.x2 + self.x3
> 
> Now, I find that sum is slow, and I want to speedup things by
> replacing sum by a call to C.

You may want to try out psyco to accelerate this code.

> 
> Looking at the manual, I can write something like:
> 
> static PyObject *sum( PyObject *self, PyObject *args )
> 
> and  the manual tells me how to access elements passed in args, but
> does not tell how to access elements (in fact attributes) of self. How
> can I retrieve self.x1, self.x2, and self.x3 as defined in the python
> class from *self passed to the C function ?
> 

PyObject_GetAttrString(self, "x1") does what you want.

Thomas