diff --git a/src/App/FeaturePython.cpp b/src/App/FeaturePython.cpp
index 66ec237c40..ef423f7f29 100644
--- a/src/App/FeaturePython.cpp
+++ b/src/App/FeaturePython.cpp
@@ -371,23 +371,26 @@ PyObject *FeaturePythonImp::getPyObject(void)
     return new FeaturePythonPyT<DocumentObjectPy>(object);
 }
 
-int FeaturePythonImp::hasChildElement() const {
-    _FC_PY_CALL_CHECK(hasChildElement,return(-1));
+FeaturePythonImp::ValueT
+FeaturePythonImp::hasChildElement() const
+{
+    _FC_PY_CALL_CHECK(hasChildElement,return(NotImplemented));
     Base::PyGILStateLocker lock;
     try {
         Py::Tuple args(1);
         args.setItem(0, Py::Object(object->getPyObject(), true));
         Py::Boolean ok(Base::pyCall(py_hasChildElement.ptr(),args.ptr()));
-        return static_cast<bool>(ok) ? 1 : 0;
+        return static_cast<bool>(ok) ? Accepted : Rejected;
     }
     catch (Py::Exception&) {
         if (PyErr_ExceptionMatches(PyExc_NotImplementedError)) {
             PyErr_Clear();
-            return -1;
+            return NotImplemented;
         }
+
         Base::PyException e; // extract the Python error text
         e.ReportException();
-        return 0;
+        return Rejected;
     }
 }
 
@@ -454,43 +457,48 @@ std::string FeaturePythonImp::getViewProviderName()
     return std::string();
 }
 
-int FeaturePythonImp::canLinkProperties() const {
-    _FC_PY_CALL_CHECK(canLinkProperties,return(-1));
+FeaturePythonImp::ValueT
+FeaturePythonImp::canLinkProperties() const
+{
+    _FC_PY_CALL_CHECK(canLinkProperties,return(NotImplemented));
     Base::PyGILStateLocker lock;
     try {
         Py::Tuple args(1);
         args.setItem(0, Py::Object(object->getPyObject(), true));
         Py::Boolean ok(Base::pyCall(py_canLinkProperties.ptr(),args.ptr()));
-        return ok?1:0;
+        return ok ? Accepted : Rejected;
     }
     catch (Py::Exception&) {
         if (PyErr_ExceptionMatches(PyExc_NotImplementedError)) {
             PyErr_Clear();
-            return -1;
+            return NotImplemented;
         }
         Base::PyException e; // extract the Python error text
         e.ReportException();
-        return 0;
+        return Rejected;
     }
 }
 
-int FeaturePythonImp::allowDuplicateLabel() const {
-    _FC_PY_CALL_CHECK(allowDuplicateLabel,return(-1));
+FeaturePythonImp::ValueT
+FeaturePythonImp::allowDuplicateLabel() const
+{
+    _FC_PY_CALL_CHECK(allowDuplicateLabel,return(NotImplemented));
     Base::PyGILStateLocker lock;
     try {
         Py::Tuple args(1);
         args.setItem(0, Py::Object(object->getPyObject(), true));
         Py::Boolean ok(Base::pyCall(py_allowDuplicateLabel.ptr(),args.ptr()));
-        return ok?1:0;
+        return ok ? Accepted : Rejected;
     }
     catch (Py::Exception&) {
         if (PyErr_ExceptionMatches(PyExc_NotImplementedError)) {
             PyErr_Clear();
-            return -1;
+            return NotImplemented;
         }
+
         Base::PyException e; // extract the Python error text
         e.ReportException();
-        return 0;
+        return Rejected;
     }
 }
 
@@ -514,10 +522,12 @@ int FeaturePythonImp::canLoadPartial() const {
     }
 }
 
-int FeaturePythonImp::redirectSubName(std::ostringstream &ss,
-        App::DocumentObject *topParent, App::DocumentObject *child) const 
+FeaturePythonImp::ValueT
+FeaturePythonImp::redirectSubName(std::ostringstream &ss,
+                                  App::DocumentObject *topParent,
+                                  App::DocumentObject *child) const 
 {
-    FC_PY_CALL_CHECK(redirectSubName);
+    _FC_PY_CALL_CHECK(redirectSubName,return(NotImplemented));
     Base::PyGILStateLocker lock;
     try {
         Py::Tuple args(4);
@@ -526,20 +536,21 @@ int FeaturePythonImp::redirectSubName(std::ostringstream &ss,
         args.setItem(2,topParent?Py::Object(topParent->getPyObject(),true):Py::Object());
         args.setItem(3,child?Py::Object(child->getPyObject(),true):Py::Object());
         Py::Object ret(Base::pyCall(py_redirectSubName.ptr(),args.ptr()));
-        if(ret.isNone())
-            return 0;
+        if (ret.isNone())
+            return Rejected;
         ss.str("");
         ss << ret.as_string();
-        return 1;
+        return Accepted;
     }
     catch (Py::Exception&) {
         if (PyErr_ExceptionMatches(PyExc_NotImplementedError)) {
             PyErr_Clear();
-            return -1;
+            return NotImplemented;
         }
+
         Base::PyException e; // extract the Python error text
         e.ReportException();
-        return 0;
+        return Rejected;
     }
 }
 
diff --git a/src/App/FeaturePython.h b/src/App/FeaturePython.h
index 404a7292ad..b8cad17c05 100644
--- a/src/App/FeaturePython.h
+++ b/src/App/FeaturePython.h
@@ -42,6 +42,12 @@ class Property;
 class AppExport FeaturePythonImp
 {
 public:
+    enum ValueT {
+        NotImplemented = 0, // not handled
+        Accepted = 1, // handled and accepted
+        Rejected = 2  // handled and rejected
+    };
+
     FeaturePythonImp(App::DocumentObject*);
     ~FeaturePythonImp();
 
@@ -61,19 +67,20 @@ public:
     bool getSubObjects(std::vector<std::string> &ret, int reason) const;
 
     bool getLinkedObject(App::DocumentObject *&ret, bool recurse, 
-            Base::Matrix4D *mat, bool transform, int depth) const;
+                         Base::Matrix4D *mat, bool transform, int depth) const;
 
-    int canLinkProperties() const;
+    ValueT canLinkProperties() const;
 
-    int allowDuplicateLabel() const;
+    ValueT allowDuplicateLabel() const;
 
-    int redirectSubName(std::ostringstream &ss,
-            App::DocumentObject *topParent, App::DocumentObject *child) const;
+    ValueT redirectSubName(std::ostringstream &ss,
+                           App::DocumentObject *topParent,
+                           App::DocumentObject *child) const;
 
     int canLoadPartial() const;
 
     /// return true to activate tree view group object handling
-    int hasChildElement() const;
+    ValueT hasChildElement() const;
     /// Get sub-element visibility
     int isElementVisible(const char *) const;
     /// Set sub-element visibility
@@ -235,10 +242,14 @@ public:
 
     /// return true to activate tree view group object handling
     virtual bool hasChildElement() const override {
-        int ret = imp->hasChildElement();
-        if(ret<0) 
+        switch (imp->hasChildElement()) {
+        case FeaturePythonImp::Accepted:
+            return true;
+        case FeaturePythonImp::Rejected:
+            return false;
+        default:
             return FeatureT::hasChildElement();
-        return ret?true:false;
+        }
     }
     /// Get sub-element visibility
     virtual int isElementVisible(const char *element) const override {
@@ -256,26 +267,38 @@ public:
     }
 
     virtual bool canLinkProperties() const override {
-        int ret = imp->canLinkProperties();
-        if(ret < 0)
+        switch (imp->canLinkProperties()) {
+        case FeaturePythonImp::Accepted:
+            return true;
+        case FeaturePythonImp::Rejected:
+            return false;
+        default:
             return FeatureT::canLinkProperties();
-        return ret?true:false;
+        }
     }
 
     virtual bool allowDuplicateLabel() const override {
-        int ret = imp->allowDuplicateLabel();
-        if(ret < 0)
+        switch (imp->allowDuplicateLabel()) {
+        case FeaturePythonImp::Accepted:
+            return true;
+        case FeaturePythonImp::Rejected:
+            return false;
+        default:
             return FeatureT::allowDuplicateLabel();
-        return ret?true:false;
+        }
     }
 
     virtual bool redirectSubName(std::ostringstream &ss,
             App::DocumentObject *topParent, App::DocumentObject *child) const override 
     {
-        int ret = imp->redirectSubName(ss,topParent,child);
-        if(ret < 0)
-            return FeatureT::redirectSubName(ss,topParent,child);
-        return ret?true:false;
+        switch (imp->redirectSubName(ss,topParent,child)) {
+        case FeaturePythonImp::Accepted:
+            return true;
+        case FeaturePythonImp::Rejected:
+            return false;
+        default:
+            return FeatureT::redirectSubName(ss, topParent, child);
+        }
     }
 
     virtual int canLoadPartial() const override {