PartDesign: Make Base Feature compatible with GeoFeatureGroup. fixes #0003080

The Original BaseFeature implementation had some serious issues with scoped links. It failed completely for e.g. sketches on the BaseFeature as it made a local link to refere to a out of body object. The only solution to make this work correctly is to add a proxy object into the body which is alloed to exactly that, to link outside oof the body. Something like shapebinder.

src/Mod/PartDesign/App/FeatureBase.cpp

@@ -0,0 +1,97 @@
+/***************************************************************************
+ *   Copyright (c) 2017 Stefan Tröger <stefantroeger@gmx.net>              *
+ *                                                                         *
+ *   This file is part of the FreeCAD CAx development system.              *
+ *                                                                         *
+ *   This library is free software; you can redistribute it and/or         *
+ *   modify it under the terms of the GNU Library General Public           *
+ *   License as published by the Free Software Foundation; either          *
+ *   version 2 of the License, or (at your option) any later version.      *
+ *                                                                         *
+ *   This library  is distributed in the hope that it will be useful,      *
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
+ *   GNU Library General Public License for more details.                  *
+ *                                                                         *
+ *   You should have received a copy of the GNU Library General Public     *
+ *   License along with this library; see the file COPYING.LIB. If not,    *
+ *   write to the Free Software Foundation, Inc., 59 Temple Place,         *
+ *   Suite 330, Boston, MA  02111-1307, USA                                *
+ *                                                                         *
+ ***************************************************************************/
+
+
+#include "PreCompiled.h"
+#ifndef _PreComp_
+# include <Standard_Failure.hxx>
+#endif
+
+#include <Base/Exception.h>
+#include <App/FeaturePythonPyImp.h>
+#include "Body.h"
+#include "FeatureBase.h"
+#include "FeaturePy.h"
+
+namespace PartDesign {
+
+
+PROPERTY_SOURCE(PartDesign::FeatureBase,PartDesign::Feature)
+
+FeatureBase::FeatureBase()
+{
+    BaseFeature.setScope(App::LinkScope::Global);
+    BaseFeature.setStatus(App::Property::Hidden, false);
+}
+
+Part::Feature* FeatureBase::getBaseObject(bool) const {
+    
+    return nullptr;
+}
+
+short int FeatureBase::mustExecute(void) const {
+        
+    if(BaseFeature.isTouched())
+        return 1;
+    
+    return Part::Feature::mustExecute();
+}
+
+
+App::DocumentObjectExecReturn* FeatureBase::execute(void) {
+       
+    if(!BaseFeature.getValue())
+        return new App::DocumentObjectExecReturn("BaseFeature link is not set");
+    
+    if(!BaseFeature.getValue()->isDerivedFrom(Part::Feature::getClassTypeId()))
+        return new App::DocumentObjectExecReturn("BaseFeature must be a Part::Feature");
+    
+    auto shape = static_cast<Part::Feature*>(BaseFeature.getValue())->Shape.getValue();
+    if(shape.IsNull())
+        return new App::DocumentObjectExecReturn("BaseFeature has a empty shape");
+    
+    Shape.setValue(shape);
+    
+    return StdReturn;
+}
+
+void FeatureBase::onChanged(const App::Property* prop) {
+    
+    // the BaseFeature property should track the Body BaseFeature and vice-versa
+    if (prop == &BaseFeature) {
+        
+        auto body = getFeatureBody();
+        if(!body)
+            return;
+    
+        if (BaseFeature.getValue() && body->BaseFeature.getValue() != BaseFeature.getValue()) {
+            body->BaseFeature.setValue(BaseFeature.getValue());
+        }
+    }
+    
+    Part::Feature::onChanged(prop);
+}
+
+
+
+}//namespace PartDesign
+