+ exposing onBeforeChange to Python

src/App/FeaturePython.cpp

@@ -76,6 +76,39 @@ DocumentObjectExecReturn *FeaturePythonImp::execute()
     return DocumentObject::StdReturn;
 }
 
+void FeaturePythonImp::onBeforeChange(const Property* prop)
+{
+    // Run the execute method of the proxy object.
+    Base::PyGILStateLocker lock;
+    try {
+        Property* proxy = object->getPropertyByName("Proxy");
+        if (proxy && proxy->getTypeId() == PropertyPythonObject::getClassTypeId()) {
+            Py::Object feature = static_cast<PropertyPythonObject*>(proxy)->getValue();
+            if (feature.hasAttr(std::string("onBeforeChange"))) {
+                if (feature.hasAttr("__object__")) {
+                    Py::Callable method(feature.getAttr(std::string("onBeforeChange")));
+                    Py::Tuple args(1);
+                    std::string prop_name = object->getPropertyName(prop);
+                    args.setItem(0, Py::String(prop_name));
+                    method.apply(args);
+                }
+                else {
+                    Py::Callable method(feature.getAttr(std::string("onBeforeChange")));
+                    Py::Tuple args(2);
+                    args.setItem(0, Py::Object(object->getPyObject(), true));
+                    std::string prop_name = object->getPropertyName(prop);
+                    args.setItem(1, Py::String(prop_name));
+                    method.apply(args);
+                }
+            }
+        }
+    }
+    catch (Py::Exception&) {
+        Base::PyException e; // extract the Python error text
+        e.ReportException();
+    }
+}
+
 void FeaturePythonImp::onChanged(const Property* prop)
 {
     // Run the execute method of the proxy object.

src/App/FeaturePython.h

@@ -45,6 +45,7 @@ public:
     ~FeaturePythonImp();
 
     DocumentObjectExecReturn *execute();
+    void onBeforeChange(const Property* prop);
     void onChanged(const Property* prop);
     PyObject *getPyObject(void);
 
@@ -199,6 +200,10 @@ public:
     }
 
 protected:
+    virtual void onBeforeChange(const Property* prop) {
+        FeatureT::onBeforeChange(prop);
+        imp->onBeforeChange(prop);
+    }
     virtual void onChanged(const Property* prop) {
         imp->onChanged(prop);
         FeatureT::onChanged(prop);