bugfix in unit parser

partly revert to 810fadab23
and change python string handling to "et" method

src/Base/UnitsApiPy.cpp

@@ -128,33 +128,25 @@ PyMethodDef UnitsApi::Methods[] = {
 
 PyObject* UnitsApi::sParseQuantity(PyObject * /*self*/, PyObject *args,PyObject * /*kwd*/)
 {
-    PyObject * object;
-    if (PyArg_ParseTuple(args,"O", &object)) {
-
-        if (PyString_Check(object) || PyUnicode_Check(object)) {
-
-            QString qstr;
-            if (PyUnicode_Check(object)) {
-
-                PyObject * utf8str = PyUnicode_AsUTF8String(object);
-
-                qstr = QString::fromUtf8(PyString_AsString(utf8str));
-                Py_DECREF(utf8str);
-            }
-            else {
-
-                qstr = QString::fromUtf8(PyString_AsString(object));
-            }
-            Quantity rtn;
-
-            try {
-
-                rtn = Quantity::parse(qstr);
-
-            }
-
-            catch (const Base::Exception&) {
-                PyErr_Format(PyExc_IOError, "invalid unit expression \n");
-                return 0L;
-            }
+    char *pstr;
+    if (!PyArg_ParseTuple(args, "et", "utf-8", &pstr))     // convert args: Python->C
+        return NULL;                             // NULL triggers exception
+
+	Quantity rtn;
+	QString qstr = QString::fromUtf8(pstr);
+	PyMem_Free(pstr);
+    try {
+        rtn = Quantity::parse(QString::fromLatin1(pstr));
+	}
+    catch (const Base::Exception&) {
+        PyErr_Format(PyExc_IOError, "invalid unit expression \n");
+        return 0L;
+    }
+    catch (const std::exception&) {
+        PyErr_Format(PyExc_IOError, "invalid unit expression \n");
+        return 0L;
+    }
+
+	return new QuantityPy(new Quantity(rtn));
+
 }