Problems extending Python with C.

[Steinar Knutsen]

I do not understand why I only can use the function ncmp as defined below
properly in the sort method of a list when I put a Python function as a
wrapper around it.

Or in other words:
import numcompare
b = somefunctiongeneratingalistofstrings()
b.sort(numcompare.ncmp)
# b does not get sorted

Whereas
import numcompare
b = somefunctiongeneratingalistofstrings()
def NCMP(x,y):
   return numcompare.ncmp(x,y)
b.sort(NCMP)
# b is sorted correctly

C-source for module:
------------------------------------------------------------------------
#include <string.h>
#include "/usr/local/include/python1.5/Python.h"

static PyObject * ncmp(PyObject *self, PyObject *args)
{
   const char* x;
   const char* y;
   long cc;

   if (!PyArg_ParseTuple(args, "ss", &x, &y)) {
      return NULL;
   }
   else {
      cc = numcompare(x, y);
      if (cc > 0) {
         return Py_BuildValue("i", 1);
      }
      else if ( cc == 0 ) {
         return Py_BuildValue("i", 0);
      }
      else {
         return Py_BuildValue("i", -1);
      }
   }
}

int numcompare(char* x, char* y)
{
   int i0 = -1, i1 = -1;
   char* endx;
   char* endy;
   int lenx, leny;
   long X, Y;

   lenx = strlen(x)-1;
   leny = strlen(y)-1;
   while ( i0 < lenx && i1 < leny ) {
      i0++;
      i1++;
      if ( ( x[i0] >= '0' && x[i0] <= '9' ) &&
           ( y[i1] >= '0' && y[i1] <= '9' ) ) {
         X = strtol(x+i0, &endx, 10);
         Y = strtol(y+i1, &endy, 10);
         }
         if ( X != Y ) {
            return X-Y;
         }
         else {
            /* -1 on cause of increment in start of while-loop */
            i0 = (int)(endx - x) - 1;
            i1 = (int)(endy - y) - 1;
            continue;
         }
      if ( x[i0] != y[i1] ) {
         return x[i0]-y[i1];
      }
   }
   return strcmp(x, y);
}

static struct PyMethodDef functions[] = {
   { "ncmp", ncmp, 1},
   { NULL, NULL}
};

void initnumcompare()
{
   (void)Py_InitModule("numcompare", functions);
}
-----------------------------------------------------------------------

I guess I'm missing something very obvious here, but I just don't get
what. The Python is 1.5.2, the compiler is GCC 2.7.2.2, the OS is NetBSD
1.3.3. (Yeah, I know I should upgrade, but the system works. :) )

Thanks for any and all help.
-- 
Steinar