Extending Python the right way...

[JB]

I'd like to have a Python class
class SL ...
that represents for example a straight line. So it has 3 
coordimates, a b and c. But a, b and c mut be multi 
precision numbers and I cannot use Python for this. So I 
should like to associate to each instance of my Sl class 
three C++ objects (multi precision numbers, provided by an 
external C++ library. I thought, I could simply right a 
Python extension for this, but it is not clear to me, if 
this would really be the right solution.

For example having three classes
class POINT #represents point
class SL #straight line

g = SL(1,2,5)
h = SL(3,-1,0)
p = section(g,h)

where p is an instance of the class point. The section would 
be computed inside C++, that is the coordinates of the 
resulting point would be computed in C++ and they should 
again be associated with the instance of the class POINT.

If I use Python floats for the coordinates, things are very 
simple as I can stay within Python. (I have alread written 
a working prototype.)

But it would be very nice if I could use the multi precision 
arithmetic offered by an external C++ library.

Could anybody give me a hint, how to proceed?

TIA, 

-- 
Janos Blazi