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

src/Mod/Sketcher/App/SketchObjectPy.xml

@@ -63,6 +63,14 @@
         <UserDocu>Rename a constraint of the sketch</UserDocu>
       </Documentation>
     </Methode>
+    <Methode Name="getIndexByName" Const="true">
+      <Documentation>
+        <UserDocu>
+Get the index of the constraint by name.
+If there is no such constraint an exception is raised.
+        </UserDocu>
+      </Documentation>
+    </Methode>
     <Methode Name="carbonCopy">
         <Documentation>
             <UserDocu>copy another sketch's geometry and constraints</UserDocu>
@@ -88,7 +96,7 @@
         <UserDocu>set the Datum of a Distance or Angle constraint</UserDocu>
       </Documentation>
     </Methode>
-    <Methode Name="getDatum">
+    <Methode Name="getDatum" Const="true">
       <Documentation>
         <UserDocu>Get the value of a datum constraint</UserDocu>
       </Documentation>
@@ -108,7 +116,7 @@
         <UserDocu>Moves all datum constraints to the end of the constraint list</UserDocu>
       </Documentation>
     </Methode>
-    <Methode Name="getDriving">
+    <Methode Name="getDriving" Const="true">
       <Documentation>
         <UserDocu>Get the Driving status of a datum constraint</UserDocu>
       </Documentation>
@@ -138,7 +146,7 @@
             <UserDocu>sets the constraint on/off (enforced or not)</UserDocu>
         </Documentation>
     </Methode>
-    <Methode Name="getActive">
+    <Methode Name="getActive" Const="true">
         <Documentation>
             <UserDocu>Get the constraint status (enforced or not)</UserDocu>
         </Documentation>
@@ -163,14 +171,14 @@
         </UserDocu>
       </Documentation>
     </Methode>
-    <Methode Name="getPoint">
+    <Methode Name="getPoint" Const="true">
       <Documentation>
         <UserDocu>
           getPoint(GeoIndex,PointPos) - retrieve the vector of a point in the sketch
         </UserDocu>
       </Documentation>
     </Methode>
-    <Methode Name="getAxis">
+    <Methode Name="getAxis" Const="true">
       <Documentation>
         <UserDocu>
           return an axis based on the corresponding construction line

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;