add method to sketch object to get index by user-defined name

src/Mod/Sketcher/App/SketchObjectPyImp.cpp

@@ -406,6 +406,31 @@ PyObject* SketchObjectPy::renameConstraint(PyObject *args)
     Py_Return;
 }
 
+PyObject* SketchObjectPy::getIndexByName(PyObject *args)
+{
+    char* utf8Name;
+    if (!PyArg_ParseTuple(args, "et", "utf-8", &utf8Name))
+        return 0;
+
+    std::string Name = utf8Name;
+    PyMem_Free(utf8Name);
+
+    if (Name.empty()) {
+        PyErr_SetString(PyExc_ValueError, "Passed string is empty");
+        return 0;
+    }
+
+    const std::vector< Sketcher::Constraint * > &vals = getSketchObjectPtr()->Constraints.getValues();
+    for (std::size_t i = 0; i < vals.size(); ++i) {
+        if (Name == vals[i]->Name) {
+            return Py_BuildValue("i", i);
+        }
+    }
+
+    PyErr_SetString(PyExc_LookupError, "No such constraint found");
+    return 0;
+}
+
 PyObject* SketchObjectPy::carbonCopy(PyObject *args)
 {
     char *ObjectName;