diff --git a/src/App/DocumentObject.cpp b/src/App/DocumentObject.cpp
index daac1f756..476d87412 100644
--- a/src/App/DocumentObject.cpp
+++ b/src/App/DocumentObject.cpp
@@ -82,10 +82,9 @@ DocumentObjectExecReturn *DocumentObject::execute(void)
 {
     //call all extensions
     auto vector = getExtensionsDerivedFromType<App::DocumentObjectExtension>();
-    for(auto ext : vector) {
-        if(ext->extensionMustExecute()) 
-            ext->extensionExecute();
-    }
+    for(auto ext : vector)
+        ext->extensionExecute();
+
     return StdReturn;
 }
 
diff --git a/src/App/Extension.h b/src/App/Extension.h
index 65583ef83..c164a721b 100644
--- a/src/App/Extension.h
+++ b/src/App/Extension.h
@@ -53,6 +53,13 @@ void * _class_::create(void){\
    return new _class_ ();\
 }
 
+/// define to implement a  subclass of Base::BaseClass
+#define EXTENSION_TYPESYSTEM_SOURCE_ABSTRACT_P(_class_) \
+Base::Type _class_::getExtensionClassTypeId(void) { return _class_::classTypeId; } \
+Base::Type _class_::getExtensionTypeId(void) const { return _class_::classTypeId; } \
+Base::Type _class_::classTypeId = Base::Type::badType();  \
+void * _class_::create(void){return 0;}
+
 /// define to implement a subclass of Base::BaseClass
 #define EXTENSION_TYPESYSTEM_SOURCE(_class_, _parentclass_) \
 EXTENSION_TYPESYSTEM_SOURCE_P(_class_);\
@@ -248,7 +255,7 @@ public:
     
     /** @name TypeHandling */
     //@{
-    bool isDerivedFrom(const Base::Type type) const {return getExtensionTypeId().isDerivedFrom(type);}
+    bool extensionIsDerivedFrom(const Base::Type type) const {return getExtensionTypeId().isDerivedFrom(type);}
 protected:
     static void initExtensionSubclass(Base::Type &toInit,const char* ClassName, const char *ParentName, 
                              Base::Type::instantiationMethod method=0);
diff --git a/src/App/ExtensionContainer.h b/src/App/ExtensionContainer.h
index dc6e42b88..ca13f5b34 100644
--- a/src/App/ExtensionContainer.h
+++ b/src/App/ExtensionContainer.h
@@ -186,14 +186,10 @@ private:
 
 /// We make sur that the PropertyData of the container is not connected to the one of the extension
 #define PROPERTY_SOURCE_WITH_EXTENSIONS(_class_, _parentclass_) \
-TYPESYSTEM_SOURCE_P(_class_);\
-const App::PropertyData * _class_::getPropertyDataPtr(void){return &propertyData;} \
-const App::PropertyData & _class_::getPropertyData(void) const{return propertyData;} \
-App::PropertyData _class_::propertyData; \
-void _class_::init(void){\
-  initSubclass(_class_::classTypeId, #_class_ , #_parentclass_, &(_class_::create) ); \
-  _class_::propertyData.parentPropertyData = _parentclass_::getPropertyDataPtr();\
-}
+    PROPERTY_SOURCE(_class_, _parentclass_)
+
+#define PROPERTY_SOURCE_ABSTRACT_WITH_EXTENSIONS(_class_, _parentclass_) \
+    PROPERTY_SOURCE_ABSTRACT(_class_, _parentclass_)
 
 } //App
 
diff --git a/src/Mod/Part/App/AppPart.cpp b/src/Mod/Part/App/AppPart.cpp
index af49edf33..bc4c86d7b 100644
--- a/src/Mod/Part/App/AppPart.cpp
+++ b/src/Mod/Part/App/AppPart.cpp
@@ -118,7 +118,7 @@
 #include "PropertyGeometryList.h"
 #include "DatumFeature.h"
 #include "Attacher.h"
-#include "AttachableObject.h"
+#include "AttachExtension.h"
 #include "FaceMaker.h"
 #include "FaceMakerCheese.h"
 #include "FaceMakerBullseye.h"
@@ -397,11 +397,12 @@ PyMODINIT_FUNC initPart()
     Attacher::AttachEnginePlane   ::init();
     Attacher::AttachEngineLine    ::init();
     Attacher::AttachEnginePoint   ::init();
+    
+    Part::AttachExtension       ::init();
+    Part::AttachExtensionPython ::init();
 
     Part::Feature               ::init();
     Part::FeatureExt            ::init();
-    Part::AttachableObject      ::init();
-    Part::AttachableObjectPython::init();
     Part::BodyBase              ::init();
     Part::FeaturePython         ::init();
     Part::FeatureGeometrySet    ::init();
diff --git a/src/Mod/Part/App/AttachEnginePyImp.cpp b/src/Mod/Part/App/AttachEnginePyImp.cpp
index 259f1e76f..fe2abd3c7 100644
--- a/src/Mod/Part/App/AttachEnginePyImp.cpp
+++ b/src/Mod/Part/App/AttachEnginePyImp.cpp
@@ -6,7 +6,7 @@
 #include "Mod/Part/App/Attacher.h"
 #include <Base/PlacementPy.h>
 #include <App/DocumentObjectPy.h>
-#include "AttachableObjectPy.h"
+#include "AttachExtensionPy.h"
 #include "TopoShapePy.h"
 
 #include "OCCError.h"
@@ -493,12 +493,12 @@ PyObject* AttachEnginePy::readParametersFromFeature(PyObject* args)
         return NULL;    // NULL triggers exception
 
     try{
-        const App::DocumentObjectPy* dobjpy = static_cast<const App::DocumentObjectPy*>(obj);
-        const App::DocumentObject* dobj = dobjpy->getDocumentObjectPtr();
-        if (! dobj->isDerivedFrom(Part::AttachableObject::getClassTypeId())){
-            throw Py::TypeError("Supplied object isn't Part::AttachableObject");
+        App::DocumentObjectPy* dobjpy = static_cast<App::DocumentObjectPy*>(obj);
+        App::DocumentObject* dobj = dobjpy->getDocumentObjectPtr();
+        if (! dobj->hasExtension(Part::AttachExtension::getExtensionClassTypeId())){
+            throw Py::TypeError("Supplied object has no Part::AttachExtension");
         }
-        const Part::AttachableObject* feat = static_cast<const Part::AttachableObject*>(dobj);
+        Part::AttachExtension* feat = dobj->getExtensionByType<Part::AttachExtension>();
         AttachEngine &attacher = *(this->getAttachEnginePtr());
         attacher.setUp(feat->Support,
                        eMapMode(feat->MapMode.getValue()),
@@ -519,10 +519,10 @@ PyObject* AttachEnginePy::writeParametersToFeature(PyObject* args)
     try{
         App::DocumentObjectPy* dobjpy = static_cast<App::DocumentObjectPy*>(obj);
         App::DocumentObject* dobj = dobjpy->getDocumentObjectPtr();
-        if (! dobj->isDerivedFrom(Part::AttachableObject::getClassTypeId())){
-            throw Py::TypeError("Supplied object isn't Part::AttachableObject");
+        if (! dobj->hasExtension(Part::AttachExtension::getExtensionClassTypeId())){
+            throw Py::TypeError("Supplied object has no Part::AttachExtension");
         }
-        Part::AttachableObject* feat = static_cast<Part::AttachableObject*>(dobj);
+        Part::AttachExtension* feat = dobj->getExtensionByType<Part::AttachExtension>();
         const AttachEngine &attacher = *(this->getAttachEnginePtr());
         AttachEngine::verifyReferencesAreSafe(attacher.references);
         feat->Support.Paste(attacher.references);
diff --git a/src/Mod/Part/App/AttachableObject.cpp b/src/Mod/Part/App/AttachExtension.cpp
similarity index 89%
rename from src/Mod/Part/App/AttachableObject.cpp
rename to src/Mod/Part/App/AttachExtension.cpp
index 30629db3c..f7b9cb542 100644
--- a/src/Mod/Part/App/AttachableObject.cpp
+++ b/src/Mod/Part/App/AttachExtension.cpp
@@ -25,19 +25,19 @@
 #ifndef _PreComp_
 #endif
 
-#include "AttachableObject.h"
+#include "AttachExtension.h"
 
 #include <Base/Console.h>
 #include <App/Application.h>
 
 #include <App/FeaturePythonPyImp.h>
-#include "AttachableObjecty.h"
+#include "AttachExtensionPy.h"
 
 
 using namespace Part;
 using namespace Attacher;
 
-EXTENSION_PROPERTY_SOURCE(Part::AttachExtension, Part::Feature);
+EXTENSION_PROPERTY_SOURCE(Part::AttachExtension, App::DocumentObjectExtension);
 
 AttachExtension::AttachExtension()
    :  _attacher(0)
@@ -126,10 +126,17 @@ bool AttachExtension::positionBySupport()
     };
 }
 
-App::DocumentObjectExecReturn *AttachExtension::exttensionExecute()
+short int AttachExtension::extensionMustExecute(void) {
+    return DocumentObjectExtension::extensionMustExecute();
+}
+
+
+App::DocumentObjectExecReturn *AttachExtension::extensionExecute()
 {
+    Base::Console().Message("Execute Extension");
     if(this->isTouched_Mapping()) {
         try{
+            Base::Console().Message("Call position by support");
             positionBySupport();
         } catch (Base::Exception &e) {
             return new App::DocumentObjectExecReturn(e.what());
@@ -153,11 +160,11 @@ void AttachExtension::extensionOnChanged(const App::Property* prop)
             try{
                 bAttached = positionBySupport();
             } catch (Base::Exception &e) {
-                this->setError();
+                getExtendedObject()->setStatus(App::Error, true);
                 Base::Console().Error("PositionBySupport: %s",e.what());
                 //set error message - how?
             } catch (Standard_Failure &e){
-                this->setError();
+                getExtendedObject()->setStatus(App::Error, true);
                 Base::Console().Error("PositionBySupport: %s",e.GetMessageString());
             }
 
@@ -195,23 +202,22 @@ App::PropertyPlacement& AttachExtension::getPlacement() {
     return static_cast<App::GeoFeature*>(getExtendedObject())->Placement;
 }
 
+PyObject* AttachExtension::getExtensionPyObject(void) {
+    
+    if (ExtensionPythonObject.is(Py::_None())){
+        // ref counter is set to 1
+        ExtensionPythonObject = Py::Object(new AttachExtensionPy(this),true);
+    }
+    return Py::new_reference_to(ExtensionPythonObject);
+}
+
 
 namespace App {
 /// @cond DOXERR
   EXTENSION_PROPERTY_SOURCE_TEMPLATE(Part::AttachExtensionPython, Part::AttachExtension)
-  template<> const char* Part::AttachExtensionPython::getViewProviderName(void) const {
-    return "PartGui::ViewProviderPython";
-  }
-  template<> PyObject* Part::AttachExtensionPython::getPyObject(void) {
-        if (PythonObject.is(Py::_None())) {
-            // ref counter is set to 1
-            PythonObject = Py::Object(new FeaturePythonPyT<Part::AttachExtensionPy>(this),true);
-        }
-        return Py::new_reference_to(PythonObject);
-  }
 /// @endcond
 
 // explicit template instantiation
-  template class PartExport FeaturePythonT<Part::AttachExtension>;
+  template class PartExport ExtensionPythonT<Part::AttachExtension>;
 }
 
diff --git a/src/Mod/Part/App/AttachableObject.h b/src/Mod/Part/App/AttachExtension.h
similarity index 94%
rename from src/Mod/Part/App/AttachableObject.h
rename to src/Mod/Part/App/AttachExtension.h
index 3f883134a..c340c8f7a 100644
--- a/src/Mod/Part/App/AttachableObject.h
+++ b/src/Mod/Part/App/AttachExtension.h
@@ -21,7 +21,7 @@
  *                                                                         *
  ***************************************************************************/
 /**
-  * AttachableObject.h, .cpp contain a class to derive other features from, to make
+  * AttachExtensionh, .cpp contain a extension class to derive other features from, to make
   * them attachable.
   */
 
@@ -100,7 +100,9 @@ public:
     virtual bool isTouched_Mapping()
     {return true; /*support.isTouched isn't true when linked objects are changed... why?..*/};
 
-    App::DocumentObjectExecReturn *extensionExecute(void);
+    virtual short int extensionMustExecute(void);
+    virtual App::DocumentObjectExecReturn *extensionExecute(void);
+    virtual PyObject* getExtensionPyObject(void);
 protected:
     virtual void extensionOnChanged(const App::Property* /*prop*/);
     
diff --git a/src/Mod/Part/App/AttachableObjectPy.xml b/src/Mod/Part/App/AttachExtensionPy.xml
similarity index 83%
rename from src/Mod/Part/App/AttachableObjectPy.xml
rename to src/Mod/Part/App/AttachExtensionPy.xml
index d9514a901..df5f91dd3 100644
--- a/src/Mod/Part/App/AttachableObjectPy.xml
+++ b/src/Mod/Part/App/AttachExtensionPy.xml
@@ -1,15 +1,14 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <GenerateModel xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="generateMetaModel_Module.xsd">
   <PythonExport 
-    Father="PartFeaturePy"  
-    Name="AttachableObjectPy" 
-    PythonName="Part.AttachableObject"
-    Twin="AttachableObject" 
-    TwinPointer="AttachableObject" 
-    Include="Mod/Part/App/AttachableObject.h" 
+    Father="DocumentObjectExtensionPy"  
+    Name="AttachExtensionPy" 
+    Twin="AttachExtension" 
+    TwinPointer="AttachExtension" 
+    Include="Mod/Part/App/AttachExtension.h" 
     Namespace="Part" 
-    FatherInclude="Mod/Part/App/PartFeaturePy.h" 
-    FatherNamespace="Part">
+    FatherInclude="App/DocumentObjectExtensionPy.h" 
+    FatherNamespace="App">
     <Documentation>
       <Author Licence="LGPL" Name="DeepSOIC" EMail="vv.titov@gmail.com" />
       <UserDocu>This object represents an attachable object with OCC shape.</UserDocu>
diff --git a/src/Mod/Part/App/AttachableObjectPyImp.cpp b/src/Mod/Part/App/AttachExtensionPyImp.cpp
similarity index 65%
rename from src/Mod/Part/App/AttachableObjectPyImp.cpp
rename to src/Mod/Part/App/AttachExtensionPyImp.cpp
index aa45e065b..3740c5991 100644
--- a/src/Mod/Part/App/AttachableObjectPyImp.cpp
+++ b/src/Mod/Part/App/AttachExtensionPyImp.cpp
@@ -1,30 +1,30 @@
 
 #include "PreCompiled.h"
 
-#include "Mod/Part/App/AttachableObject.h"
+#include "Mod/Part/App/AttachExtension.h"
 #include "OCCError.h"
 
 #include "AttachEnginePy.h"
 
-// inclusion of the generated files (generated out of AttachableObjectPy.xml)
-#include "AttachableObjectPy.h"
-#include "AttachableObjectPy.cpp"
+// inclusion of the generated files (generated out of AttachExtensionPy.xml)
+#include "AttachExtensionPy.h"
+#include "AttachExtensionPy.cpp"
 
 using namespace Part;
 
 // returns a string which represents the object e.g. when printed in python
-std::string AttachableObjectPy::representation(void) const
+std::string AttachExtensionPy::representation(void) const
 {
     return std::string("<Part::AttachableObject>");
 }
 
-PyObject* AttachableObjectPy::positionBySupport(PyObject *args)
+PyObject* AttachExtensionPy::positionBySupport(PyObject *args)
 {
     if (!PyArg_ParseTuple(args, ""))
         return 0;
     bool bAttached = false;
     try{
-        bAttached = this->getAttachableObjectPtr()->positionBySupport();
+        bAttached = this->getAttachExtensionPtr()->positionBySupport();
     } catch (Standard_Failure) {
         Handle_Standard_Failure e = Standard_Failure::Caught();
         PyErr_SetString(PartExceptionOCCError, e->GetMessageString());
@@ -36,14 +36,14 @@ PyObject* AttachableObjectPy::positionBySupport(PyObject *args)
     return Py::new_reference_to(Py::Boolean(bAttached));
 }
 
-PyObject* AttachableObjectPy::changeAttacherType(PyObject *args)
+PyObject* AttachExtensionPy::changeAttacherType(PyObject *args)
 {
     const char* typeName;
     if (!PyArg_ParseTuple(args, "s", &typeName))
         return 0;
     bool ret;
     try{
-        ret = this->getAttachableObjectPtr()->changeAttacherType(typeName);
+        ret = this->getAttachExtensionPtr()->changeAttacherType(typeName);
     } catch (Standard_Failure) {
         Handle_Standard_Failure e = Standard_Failure::Caught();
         PyErr_SetString(PartExceptionOCCError, e->GetMessageString());
@@ -55,16 +55,16 @@ PyObject* AttachableObjectPy::changeAttacherType(PyObject *args)
     return Py::new_reference_to(Py::Boolean(ret));
 }
 
-Py::Object AttachableObjectPy::getAttacher(void) const
+Py::Object AttachExtensionPy::getAttacher(void) const
 {
     try {
-        this->getAttachableObjectPtr()->attacher(); //throws if attacher is not set
+        this->getAttachExtensionPtr()->attacher(); //throws if attacher is not set
     } catch (Base::Exception) {
         return Py::None();
     }
 
     try {
-        return Py::Object( new Attacher::AttachEnginePy(this->getAttachableObjectPtr()->attacher().copy()), true);
+        return Py::Object( new Attacher::AttachEnginePy(this->getAttachExtensionPtr()->attacher().copy()), true);
     } catch (Standard_Failure) {
         Handle_Standard_Failure e = Standard_Failure::Caught();
         throw Py::Exception(Part::PartExceptionOCCError, e->GetMessageString());
@@ -74,12 +74,12 @@ Py::Object AttachableObjectPy::getAttacher(void) const
 
 }
 
-PyObject *AttachableObjectPy::getCustomAttributes(const char* /*attr*/) const
+PyObject *AttachExtensionPy::getCustomAttributes(const char* /*attr*/) const
 {
     return 0;
 }
 
-int AttachableObjectPy::setCustomAttributes(const char* /*attr*/, PyObject* /*obj*/)
+int AttachExtensionPy::setCustomAttributes(const char* /*attr*/, PyObject* /*obj*/)
 {
     return 0;
 }
diff --git a/src/Mod/Part/App/CMakeLists.txt b/src/Mod/Part/App/CMakeLists.txt
index 7623c2b91..6d9217e7e 100644
--- a/src/Mod/Part/App/CMakeLists.txt
+++ b/src/Mod/Part/App/CMakeLists.txt
@@ -73,7 +73,7 @@ generate_from_xml(RectangularTrimmedSurfacePy)
 generate_from_xml(SurfaceOfExtrusionPy)
 generate_from_xml(SurfaceOfRevolutionPy)
 generate_from_xml(PartFeaturePy)
-generate_from_xml(AttachableObjectPy)
+generate_from_xml(AttachExtensionPy)
 generate_from_xml(Part2DObjectPy)
 generate_from_xml(AttachEnginePy)
 generate_from_xml(TopoShapePy)
@@ -169,8 +169,8 @@ SET(Features_SRCS
     BodyBase.cpp
     DatumFeature.cpp
     DatumFeature.h
-    AttachableObject.h
-    AttachableObject.cpp
+    AttachExtension.h
+    AttachExtension.cpp
 )
 SOURCE_GROUP("Features" FILES ${Features_SRCS})
 
@@ -251,8 +251,8 @@ SET(Python_SRCS
     SurfaceOfRevolutionPyImp.cpp
     PartFeaturePy.xml
     PartFeaturePyImp.cpp
-    AttachableObjectPy.xml
-    AttachableObjectPyImp.cpp
+    AttachExtensionPy.xml
+    AttachExtensionPyImp.cpp
     Part2DObjectPy.xml
     Part2DObjectPyImp.cpp
     AttachEnginePy.xml
diff --git a/src/Mod/Part/App/DatumFeature.cpp b/src/Mod/Part/App/DatumFeature.cpp
index e907ae8d7..bdb62317c 100644
--- a/src/Mod/Part/App/DatumFeature.cpp
+++ b/src/Mod/Part/App/DatumFeature.cpp
@@ -32,10 +32,11 @@
 using namespace Part;
 using namespace Attacher;
 
-PROPERTY_SOURCE_ABSTRACT(Part::Datum, Part::AttachableObject)
+PROPERTY_SOURCE_ABSTRACT_WITH_EXTENSIONS(Part::Datum, Part::Feature)
 
 Datum::Datum(void)
 {
+    AttachExtension::initExtension(this);
     touch();
 }
 
@@ -47,7 +48,7 @@ void Datum::onDocumentRestored()
 {
     // This seems to be the only way to make the ViewProvider display the datum feature
     Support.touch();
-    AttachableObject::onDocumentRestored();
+    Part::Feature::onDocumentRestored();
 }
 
 TopoDS_Shape Datum::getShape() const
diff --git a/src/Mod/Part/App/DatumFeature.h b/src/Mod/Part/App/DatumFeature.h
index 916d23f4c..30f5162cf 100644
--- a/src/Mod/Part/App/DatumFeature.h
+++ b/src/Mod/Part/App/DatumFeature.h
@@ -28,7 +28,7 @@
 #include <App/PropertyLinks.h>
 
 #include "PartFeature.h"
-#include "AttachableObject.h"
+#include "AttachExtension.h"
 
 namespace Part
 {
@@ -36,9 +36,9 @@ namespace Part
 // This generic class is defined here so that the Sketcher module can access datum features
 // without creating a dependency on PartDesign
 
-class PartExport Datum : public Part::AttachableObject
+class PartExport Datum : public Part::Feature, public Part::AttachExtension
 {
-    PROPERTY_HEADER(Part::Datum);
+    PROPERTY_HEADER_WITH_EXTENSIONS(Part::Datum);
 
 public:
     Datum();
diff --git a/src/Mod/Part/App/Part2DObject.cpp b/src/Mod/Part/App/Part2DObject.cpp
index e5858a253..2df617c1f 100644
--- a/src/Mod/Part/App/Part2DObject.cpp
+++ b/src/Mod/Part/App/Part2DObject.cpp
@@ -62,18 +62,19 @@ const int Part2DObject::H_Axis = -1;
 const int Part2DObject::V_Axis = -2;
 const int Part2DObject::N_Axis = -3;
 
-PROPERTY_SOURCE(Part::Part2DObject, Part::AttachableObject)
+PROPERTY_SOURCE_WITH_EXTENSIONS(Part::Part2DObject, Part::Feature)
 
 
 Part2DObject::Part2DObject()
 {
+    AttachExtension::initExtension(this);
     this->setAttacher(new Attacher::AttachEnginePlane);
 }
 
 
 App::DocumentObjectExecReturn *Part2DObject::execute(void)
 {
-    return AttachableObject::execute();
+    return Feature::execute();
 }
 
 void Part2DObject::transformPlacement(const Base::Placement &transform)
diff --git a/src/Mod/Part/App/Part2DObject.h b/src/Mod/Part/App/Part2DObject.h
index 9041ebb97..c4d19dacf 100644
--- a/src/Mod/Part/App/Part2DObject.h
+++ b/src/Mod/Part/App/Part2DObject.h
@@ -29,7 +29,7 @@
 #include <Base/Axis.h>
 
 #include "PartFeature.h"
-#include "AttachableObject.h"
+#include "AttachExtension.h"
 
 class TopoDS_Face;
 
@@ -50,9 +50,9 @@ class Geometry;
   * geometry as its descend Sketcher::SketchObject .
   */
 
-class PartExport Part2DObject : public Part::AttachableObject
+class PartExport Part2DObject : public Part::Feature, public Part::AttachExtension
 {
-    PROPERTY_HEADER(Part::Part2DObject);
+    PROPERTY_HEADER_WITH_EXTENSIONS(Part::Part2DObject);
 
 public:
     Part2DObject();
diff --git a/src/Mod/Part/App/Part2DObjectPy.xml b/src/Mod/Part/App/Part2DObjectPy.xml
index 299bcd84d..231276087 100644
--- a/src/Mod/Part/App/Part2DObjectPy.xml
+++ b/src/Mod/Part/App/Part2DObjectPy.xml
@@ -1,13 +1,13 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <GenerateModel xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="generateMetaModel_Module.xsd">
   <PythonExport 
-    Father="AttachableObjectPy"
+    Father="PartFeaturePy"
     Name="Part2DObjectPy" 
     Twin="Part2DObject" 
     TwinPointer="Part2DObject" 
     Include="Mod/Part/App/Part2DObject.h" 
     Namespace="Part" 
-    FatherInclude="Mod/Part/App/AttachableObjectPy.h"
+    FatherInclude="Mod/Part/App/PartFeaturePy.h"
     FatherNamespace="Part">
     <Documentation>
       <Author Licence="LGPL" Name="Juergen Riegel" EMail="FreeCAD@juergen-riegel.net" />
diff --git a/src/Mod/Part/App/PartFeature.cpp b/src/Mod/Part/App/PartFeature.cpp
index 2485dcaaf..203493582 100644
--- a/src/Mod/Part/App/PartFeature.cpp
+++ b/src/Mod/Part/App/PartFeature.cpp
@@ -93,7 +93,7 @@ App::DocumentObjectExecReturn *Feature::recompute(void)
 App::DocumentObjectExecReturn *Feature::execute(void)
 {
     this->Shape.touch();
-    return App::DocumentObject::StdReturn;
+    return GeoFeature::execute();
 }
 
 PyObject *Feature::getPyObject(void)
diff --git a/src/Mod/Part/App/PrimitiveFeature.cpp b/src/Mod/Part/App/PrimitiveFeature.cpp
index 9170e4c3b..fef056f72 100644
--- a/src/Mod/Part/App/PrimitiveFeature.cpp
+++ b/src/Mod/Part/App/PrimitiveFeature.cpp
@@ -84,10 +84,11 @@ namespace Part {
 using namespace Part;
 
 
-PROPERTY_SOURCE_ABSTRACT(Part::Primitive, Part::AttachableObject)
+PROPERTY_SOURCE_ABSTRACT_WITH_EXTENSIONS(Part::Primitive, Part::Feature)
 
 Primitive::Primitive(void) 
 {
+    AttachExtension::initExtension(this);
     touch();
 }
 
@@ -100,6 +101,11 @@ short Primitive::mustExecute(void) const
     return Feature::mustExecute();
 }
 
+App::DocumentObjectExecReturn* Primitive::execute(void) {
+    return Part::Feature::execute();
+}
+
+
 void Primitive::Restore(Base::XMLReader &reader)
 {
     reader.readElement("Properties");
@@ -169,7 +175,7 @@ void Primitive::onChanged(const App::Property* prop)
             }
         }
     }
-    Part::AttachableObject::onChanged(prop);
+    Part::Feature::onChanged(prop);
 }
 
 PROPERTY_SOURCE(Part::Vertex, Part::Primitive)
@@ -191,7 +197,7 @@ short Vertex::mustExecute() const
         Y.isTouched() ||
         Z.isTouched())
         return 1;
-    return Part::AttachableObject::mustExecute();
+    return Part::Primitive::mustExecute();
 }
 
 App::DocumentObjectExecReturn *Vertex::execute(void)
@@ -205,7 +211,7 @@ App::DocumentObjectExecReturn *Vertex::execute(void)
     const TopoDS_Vertex& vertex = MakeVertex.Vertex();
     this->Shape.setValue(vertex);
 
-    return AttachableObject::execute();
+    return Primitive::execute();
 }
 
 
@@ -221,7 +227,7 @@ void Vertex::onChanged(const App::Property* prop)
             }
         }
     }
-    Part::AttachableObject::onChanged(prop);
+    Part::Primitive::onChanged(prop);
 }
 
 PROPERTY_SOURCE(Part::Line, Part::Primitive)
@@ -249,7 +255,7 @@ short Line::mustExecute() const
         Y2.isTouched() ||
         Z2.isTouched())
         return 1;
-    return Part::AttachableObject::mustExecute();
+    return Part::Primitive::mustExecute();
 }
 
 App::DocumentObjectExecReturn *Line::execute(void)
@@ -270,7 +276,7 @@ App::DocumentObjectExecReturn *Line::execute(void)
     const TopoDS_Edge& edge = mkEdge.Edge();
     this->Shape.setValue(edge);
 
-    return AttachableObject::execute();
+    return Primitive::execute();
 }
 
 void Line::onChanged(const App::Property* prop)
@@ -285,7 +291,7 @@ void Line::onChanged(const App::Property* prop)
             }
         }
     }
-    Part::AttachableObject::onChanged(prop);
+    Part::Primitive::onChanged(prop);
 }
 
 PROPERTY_SOURCE(Part::Plane, Part::Primitive)
@@ -356,7 +362,7 @@ App::DocumentObjectExecReturn *Plane::execute(void)
     TopoDS_Shape ResultShape = mkFace.Shape();
     this->Shape.setValue(ResultShape);
 
-    return AttachableObject::execute();
+    return Primitive::execute();
 }
 
 PROPERTY_SOURCE(Part::Sphere, Part::Primitive)
@@ -404,7 +410,7 @@ App::DocumentObjectExecReturn *Sphere::execute(void)
         return new App::DocumentObjectExecReturn(e->GetMessageString());
     }
 
-    return AttachableObject::execute();
+    return Primitive::execute();
 }
 
 PROPERTY_SOURCE(Part::Ellipsoid, Part::Primitive)
@@ -486,7 +492,7 @@ App::DocumentObjectExecReturn *Ellipsoid::execute(void)
         return new App::DocumentObjectExecReturn(e->GetMessageString());
     }
 
-    return AttachableObject::execute();
+    return Primitive::execute();
 }
 
 PROPERTY_SOURCE(Part::Cylinder, Part::Primitive)
@@ -529,7 +535,7 @@ App::DocumentObjectExecReturn *Cylinder::execute(void)
         return new App::DocumentObjectExecReturn(e->GetMessageString());
     }
 
-    return AttachableObject::execute();
+    return Primitive::execute();
 }
 
 App::PropertyIntegerConstraint::Constraints Prism::polygonRange = {3,INT_MAX,1};
@@ -587,7 +593,7 @@ App::DocumentObjectExecReturn *Prism::execute(void)
         return new App::DocumentObjectExecReturn(e->GetMessageString());
     }
 
-    return AttachableObject::execute();
+    return Primitive::execute();
 }
 
 App::PropertyIntegerConstraint::Constraints RegularPolygon::polygon = {3,INT_MAX,1};
@@ -639,7 +645,7 @@ App::DocumentObjectExecReturn *RegularPolygon::execute(void)
         return new App::DocumentObjectExecReturn(e->GetMessageString());
     }
 
-    return AttachableObject::execute();
+    return Primitive::execute();
 }
 
 
@@ -689,7 +695,7 @@ App::DocumentObjectExecReturn *Cone::execute(void)
         return new App::DocumentObjectExecReturn(e->GetMessageString());
     }
 
-    return AttachableObject::execute();
+    return Primitive::execute();
 }
 
 PROPERTY_SOURCE(Part::Torus, Part::Primitive)
@@ -761,7 +767,7 @@ App::DocumentObjectExecReturn *Torus::execute(void)
         return new App::DocumentObjectExecReturn(e->GetMessageString());
     }
 
-    return AttachableObject::execute();
+    return Primitive::execute();
 }
 
 PROPERTY_SOURCE(Part::Helix, Part::Primitive)
@@ -798,7 +804,7 @@ void Helix::onChanged(const App::Property* prop)
             }
         }
     }
-    Part::AttachableObject::onChanged(prop);
+    Part::Primitive::onChanged(prop);
 }
 
 short Helix::mustExecute() const
@@ -842,7 +848,7 @@ App::DocumentObjectExecReturn *Helix::execute(void)
         return new App::DocumentObjectExecReturn(e->GetMessageString());
     }
 
-    return AttachableObject::execute();
+    return Primitive::execute();
 }
 
 PROPERTY_SOURCE(Part::Spiral, Part::Primitive)
@@ -869,7 +875,7 @@ void Spiral::onChanged(const App::Property* prop)
             }
         }
     }
-    Part::AttachableObject::onChanged(prop);
+    Part::Primitive::onChanged(prop);
 }
 
 short Spiral::mustExecute() const
@@ -933,7 +939,7 @@ App::DocumentObjectExecReturn *Spiral::execute(void)
         BRepProj_Projection proj(wire, mkFace.Face(), gp::DZ());
         this->Shape.setValue(proj.Shape());
 
-        AttachableObject::execute();
+        Primitive::execute();
     }
     catch (Standard_Failure) {
         Handle_Standard_Failure e = Standard_Failure::Caught();
@@ -942,7 +948,7 @@ App::DocumentObjectExecReturn *Spiral::execute(void)
 
 
 
-    return AttachableObject::execute();
+    return Primitive::execute();
 }
 
 PROPERTY_SOURCE(Part::Wedge, Part::Primitive)
@@ -1027,7 +1033,7 @@ App::DocumentObjectExecReturn *Wedge::execute(void)
         return new App::DocumentObjectExecReturn(e->GetMessageString());
     }
 
-    return AttachableObject::execute();
+    return Primitive::execute();
 }
 
 void Wedge::onChanged(const App::Property* prop)
@@ -1070,7 +1076,7 @@ short Ellipse::mustExecute() const
         MajorRadius.isTouched() ||
         MinorRadius.isTouched())
         return 1;
-    return Part::AttachableObject::mustExecute();
+    return Part::Primitive::mustExecute();
 }
 
 App::DocumentObjectExecReturn *Ellipse::execute(void)
@@ -1084,7 +1090,7 @@ App::DocumentObjectExecReturn *Ellipse::execute(void)
     const TopoDS_Edge& edge = clMakeEdge.Edge();
     this->Shape.setValue(edge);
 
-    return AttachableObject::execute();
+    return Primitive::execute();
 }
 
 void Ellipse::onChanged(const App::Property* prop)
@@ -1099,5 +1105,5 @@ void Ellipse::onChanged(const App::Property* prop)
             }
         }
     }
-    Part::AttachableObject::onChanged(prop);
+    Part::Primitive::onChanged(prop);
 }
diff --git a/src/Mod/Part/App/PrimitiveFeature.h b/src/Mod/Part/App/PrimitiveFeature.h
index 6a7848373..f430b1d62 100644
--- a/src/Mod/Part/App/PrimitiveFeature.h
+++ b/src/Mod/Part/App/PrimitiveFeature.h
@@ -26,14 +26,14 @@
 
 #include <App/PropertyUnits.h>
 #include "PartFeature.h"
-#include "AttachableObject.h"
+#include "AttachExtension.h"
 
 namespace Part
 {
 
-class PartExport Primitive : public Part::AttachableObject
+class PartExport Primitive : public Part::Feature, public Part::AttachExtension
 {
-    PROPERTY_HEADER(Part::Primitive);
+    PROPERTY_HEADER_WITH_EXTENSIONS(Part::Primitive);
 
 public:
     Primitive();
@@ -42,7 +42,7 @@ public:
     /** @name methods override feature */
     //@{
     /// recalculate the feature
-    App::DocumentObjectExecReturn *execute(void) = 0;
+    App::DocumentObjectExecReturn *execute(void);
     short mustExecute() const;
     //@}
 
diff --git a/src/Mod/PartDesign/Gui/Command.cpp b/src/Mod/PartDesign/Gui/Command.cpp
index b3aceeb28..5cf7f4af6 100644
--- a/src/Mod/PartDesign/Gui/Command.cpp
+++ b/src/Mod/PartDesign/Gui/Command.cpp
@@ -112,7 +112,7 @@ void UnifiedDatumCommand(Gui::Command &cmd, Base::Type type, std::string name)
 
             //test if current selection fits a mode.
             if (support.getSize() > 0) {
-                Part::AttachableObject* pcDatum = static_cast<Part::AttachableObject*>(cmd.getDocument()->getObject(FeatName.c_str()));
+                Part::AttachExtension* pcDatum = cmd.getDocument()->getObject(FeatName.c_str())->getExtensionByType<Part::AttachExtension>();
                 pcDatum->attacher().references.Paste(support);
                 SuggestResult sugr;
                 pcDatum->attacher().suggestMapModes(sugr);
diff --git a/src/Mod/PartDesign/Gui/Utils.cpp b/src/Mod/PartDesign/Gui/Utils.cpp
index ee97e0811..c65861c4c 100644
--- a/src/Mod/PartDesign/Gui/Utils.cpp
+++ b/src/Mod/PartDesign/Gui/Utils.cpp
@@ -394,8 +394,8 @@ bool isFeatureMovable(App::DocumentObject* const feat)
 
     }
 
-    if (feat->getTypeId().isDerivedFrom(Part::AttachableObject::getClassTypeId())) {
-        auto attachable = static_cast<Part::AttachableObject*>(feat);
+    if (feat->hasExtension(Part::AttachExtension::getExtensionClassTypeId())) {
+        auto attachable = feat->getExtensionByType<Part::AttachExtension>();
         App::DocumentObject* support = attachable->Support.getValue();
         if (support && !support->getTypeId().isDerivedFrom(App::OriginFeature::getClassTypeId()))
             return false;
@@ -460,8 +460,8 @@ std::vector<App::DocumentObject*> collectMovableDependencies(std::vector<App::Do
 
 void relinkToOrigin(App::DocumentObject* feat, PartDesign::Body* targetbody)
 {
-    if (feat->getTypeId().isDerivedFrom(Part::AttachableObject::getClassTypeId())) {
-        auto attachable = static_cast<Part::AttachableObject*>(feat);
+    if (feat->hasExtension(Part::AttachExtension::getExtensionClassTypeId())) {
+        auto attachable = feat->getExtensionByType<Part::AttachExtension>();
         App::DocumentObject* support = attachable->Support.getValue();
         if (support && support->getTypeId().isDerivedFrom(App::OriginFeature::getClassTypeId())) {
             auto originfeat = static_cast<App::OriginFeature*>(support);