Ctypes catching exception

Question

I\'m playing a little bit with ctypes and C/C++ DLLs I have a quite simple \"math\" dll

double Divide(double a, double b)
{
    if (b == 0)
    {
       thro         


        

Answer 1

First of all you should not use exception specifications in C++. This is a horrible feature of C++ and it has been deprecated in the latest standard. Also, the syntax throw(...) is not valid C++ at all, this line does not compile with a standard conforming compiler like gcc:

double Divide(double a, double b) throw (...)

I think you are relying on a non-standard Visual C++ "extension", which is, as far as I know, useless anyway, cause Visual C++ ignores all exception specifications unless throw() has no arguments.

Going through the ctypes documentation for Python 2.7.3 I can't see any reference to C++ and throwing exceptions from C++ code called via ctypes. It seems ctypes was meant for calling C functions only and does not handle C++ exceptions.

Answer 2

Try this:

from ctypes import *

mathdll=cdll.MathFuncsDll
divide = mathdll.Divide
divide.restype = c_double
divide.argtypes = [c_double, c_double]

try:
    print divide (10,0)
except WindowsError as we:
    print we.args[0]
except:
    print "Unhandled Exception"