report type of passed argument when conversion fails

[N-Coder]

No description provided.

[wlav]

If you use PyObject_Type instead of Py_TYPE, then you get a new reference and its result needs a Py_DECREF.

__name__ is interned as CPyCppyy::PyStrings::gName, for use with PyObject_GetAttr.

Instead of PyUnicode_AsUTF8, use CPyCppyy_PyText_AsString for portability.

There is also std::string ClassName(PyObject* pyobj); in Utility.h. It differs in that it looks for __cpp_name__ before looking for __name__ but otherwise has all the ref-counting, conversions, etc. as they should be.

[N-Coder]

Could the PyErr_Clear in Utility::ClassName, which gets called when the passed object has no __cpp_name__, interfere with the following SetPyError_ and the PyErr_Fetch it calls?

std::string CPyCppyy::Utility::ClassName(PyObject* pyobj) {
    std::string clname = "<unknown>";
    PyObject* pyclass = (PyObject*)Py_TYPE(pyobj);
    PyObject* pyname = PyObject_GetAttr(pyclass, PyStrings::gCppName);
    if (!pyname) {
        PyErr_Clear();
        pyname = PyObject_GetAttr(pyclass, PyStrings::gName);
    }

[N-Coder]

I changed it to ClassName and removed the ref counting, but I'm still unsure what'll happen in case of an exception.

[wlav]

I'm thinking (not tested) that in case of an exception, PyErr_Clear would need to be called for ClassName() to succeed. I'm also thinking that if there is an exception, fetching it and using it as part of the message may be useful.