+ raise exception in TopoShape::getSubShape() if shape is empty or wrong sub-type is given

git-svn-id: https://free-cad.svn.sourceforge.net/svnroot/free-cad/trunk@5349 e8eeb9e2-ec13-0410-a4a9-efa5cf37419d

src/Mod/Part/App/TopoShape.cpp

@@ -355,7 +355,11 @@ void TopoShape::getFacesFromSubelement(const Data::Segment* element,
 
 TopoDS_Shape TopoShape::getSubShape(const char* Type) const
 {
-    if (!Type) return TopoDS_Shape();
+    if (!Type)
+        Standard_Failure::Raise("No sub-shape type given");
+    if (this->_Shape.IsNull())
+        Standard_Failure::Raise("Cannot get sub-shape from empty shape");
+
     std::string shapetype(Type);
     if (shapetype.size() > 4 && shapetype.substr(0,4) == "Face") {
         int index=std::atoi(&shapetype[4]);
@@ -376,7 +380,8 @@ TopoDS_Shape TopoShape::getSubShape(const char* Type) const
         return anIndices.FindKey(index);
     }
 
-    return TopoDS_Shape();
+    Standard_Failure::Raise("Not supported sub-shape type");
+    return TopoDS_Shape(); // avoid compiler warning
 }
 
 unsigned long TopoShape::countSubShapes(const char* Type) const

src/Mod/Sketcher/App/SketchObject.cpp

@@ -1122,7 +1122,14 @@ void SketchObject::rebuildExternalGeometry(void)
         const Part::Feature *refObj=static_cast<const Part::Feature*>(Obj);
         const Part::TopoShape& refShape=refObj->Shape.getShape();
 
-        TopoDS_Shape refSubShape=refShape.getSubShape(SubElement.c_str());
+        TopoDS_Shape refSubShape;
+        try {
+            refSubShape = refShape.getSubShape(SubElement.c_str());
+        }
+        catch (Standard_Failure) {
+            Handle_Standard_Failure e = Standard_Failure::Caught();
+            throw Base::Exception(e->GetMessageString());
+        }
 
         switch (refSubShape.ShapeType())
         {

src/Mod/Sketcher/App/SketchObjectPy.xml

@@ -45,7 +45,7 @@
     </Methode>
     <Methode Name="addExternal">
       <Documentation>
-        <UserDocu>add a link to a external geometry to use them in a constraint</UserDocu>
+        <UserDocu>add a link to an external geometry to use it in a constraint</UserDocu>
       </Documentation>
     </Methode>
     <Methode Name="delExternal">

src/Mod/Sketcher/App/SketchObjectPyImp.cpp

@@ -143,7 +143,7 @@ PyObject* SketchObjectPy::addExternal(PyObject *args)
         PyErr_SetString(PyExc_ValueError, str.str().c_str());
         return 0;
     }
-    // check if its belong to the sketch support
+    // check if it belongs to the sketch support
     if (this->getSketchObjectPtr()->Support.getValue() != Obj) {
         std::stringstream str;
         str << ObjectName << "is not supported by this sketch";