[C++-sig] debuging

[Bjorn Pettersen]

> From: Mike Rovner [mailto:mike at bindkey.com] 
> 
> Howdy, folks.
> 
> How do you debug BPL applications?
> 
> I just got 'TypeError: bad argument type for built-in 
> operation' and have absolutely no idea what to do next.

Sounds like you need to get the traceback... Here's how I do it (you'll
probably want to modify it to throw a more standard exception ;-)

-- bjorn

    std::string getTraceback() {
        std::string result;
        PyObject *exception, *v, *traceback;
        PyErr_Fetch(&exception, &v, &traceback);
        PyErr_NormalizeException(&exception, &v, &traceback);

        /*
            import traceback
            lst = traceback.format_exception(exception, v, traceback)
            for line in lst:
                result += line
        */
        PyObject* tbstr = PyString_FromString("traceback");
        PyObject* tbmod = PyImport_Import(tbstr);
        if (!tbmod) throw new NException("Unable to import traceback
module. Is your Python installed?", N_EX_NULL);
        PyObject* tbdict = PyModule_GetDict(tbmod);
        PyObject* formatFunc = PyDict_GetItemString(tbdict,
"format_exception");
        if (!formatFunc) throw new NException("Can't find
traceback.format_exception", N_EX_NULL);
        if (!traceback) {
            traceback = Py_None;
            Py_INCREF(Py_None);
        }
        PyObject* args = Py_BuildValue("(OOO)", exception, v,
traceback);
        PyObject* lst = PyObject_CallObject(formatFunc, args);

        for (int i=0; i<PyList_GET_SIZE(lst); i++) {
            result += PyString_AsString(PyList_GetItem(lst, i));
        }

        Py_DECREF(args);
        Py_DECREF(lst);
        return result;
    }