Function TryAppendTraceback

tensorflow/python/lib/core/py_util.cc:51–97

Returns a PyObject containing a string, or null

// Returns a PyObject containing a string, or null
void TryAppendTraceback(PyObject* ptype, PyObject* pvalue, PyObject* ptraceback,
                        string* out) {
  // The "traceback" module is assumed to be imported already by script_ops.py.
  PyObject* tb_module = PyImport_AddModule("traceback");

  if (!tb_module) {
    return;
  }

  PyObject* format_exception =
      PyObject_GetAttrString(tb_module, "format_exception");

  if (!format_exception) {
    return;
  }

  if (!PyCallable_Check(format_exception)) {
    Py_DECREF(format_exception);
    return;
  }

  PyObject* ret_val = PyObject_CallFunctionObjArgs(format_exception, ptype,
                                                   pvalue, ptraceback, nullptr);
  Py_DECREF(format_exception);

  if (!ret_val) {
    return;
  }

  if (!PyList_Check(ret_val)) {
    Py_DECREF(ret_val);
    return;
  }

  Py_ssize_t n = PyList_GET_SIZE(ret_val);
  for (Py_ssize_t i = 0; i < n; ++i) {
    PyObject* v = PyList_GET_ITEM(ret_val, i);
#if PY_MAJOR_VERSION < 3
    strings::StrAppend(out, PyString_AS_STRING(v), "\n");
#else
    strings::StrAppend(out, PyUnicode_AsUTF8(v), "\n");
#endif
  }

  // Iterate through ret_val.
  Py_DECREF(ret_val);
}

string PyExceptionFetch() {
  CHECK(PyErr_Occurred())