Python 3.0.1 Embedded: PyObject_Repr() or PyArg_ParseTuple() return garbage?

[jwatte]

I am embedding Python 3.0.1 on Windows, using MSVC 2008 sp1. I do not pass FILE* structs to Python, so I think compiler version differences is not a problem.

The following code has a problem, in that the "txt" string that comes out at the end only contains the character literal 1, followed by a terminating zero. I have tried it both with "u" and "s" format (changing between wchar_t * and char * for the out arg). Curiously, the result is the same -- a one-character string with ASCII 1 as the only character.

Am I doing something wrong, or is this totally bustigated? (And what happened to PyString_xxx ? Not there in 3.0 headers).

static void FormatError(wchar_t const *path, wchar_t *oError, size_t errBufSize)
{
  PyObject *ptype, *pvalue, *ptraceback;
  PyErr_Fetch(&ptype, &pvalue, &ptraceback);
  if (ptype == 0) ptype = Py_None;
  if (pvalue == 0) pvalue = Py_None;
  if (ptraceback == 0) ptraceback = Py_None;
  PyObject *a = 0, *b = 0, *c = 0;
  a = Py_BuildValue("OOO", ptype, pvalue, ptraceback);
  if (a == NULL)
  {
unknown_error:
    swprintf(oError, errBufSize, L"Unknown error in script %s.", path);
end:
    Py_XDECREF(a);
    Py_XDECREF(b);
    Py_XDECREF(c);
    return;
  }
  b = PyObject_Repr(a);
  wchar_t const *txt = 0;
  c = Py_BuildValue("(u)", b);
  PyArg_ParseTuple(c, "u", &txt);
  if (txt == NULL)
    goto unknown_error;
  swprintf(oError, errBufSize, L"%s", txt);
  goto end;
}

I'd appreciate any help or pointers you might suggest (including pointers to other forums where Python devs might hang out).

[scru]

On line 22 you have the incorrect format string for the argument b. The format string should be "(O)" as the argument is a Python object and not a null terminated wchar_t buffer.

However, it seems that all you are trying to do is get a wchar_t buffer from the repr object. This should work: wchar_t *txt = PyUnicode_AsWideChar(b);

[jwatte]

the argument is a Python object and not a null terminated wchar_t buffer

Ah! So the type is not that of the object I pass in; it's of the pointer I pass in. That clarifies things.
I had already discovered the change from PyString -> PyUnicode in 3.0, but my confusion was why the above code didn't work as I expected it to. Now I know. Thanks for your help!