How to pass a python grid function back to C++?

It seems that the grid functions created via the python interface are incompatible (or only partially compatible) with the grid functions in dune-functions.

What I tried:

• interpolate a functions via python (basis.interpolate)
• take the vector and create a discrete function (basis.asFunction)
• pass this function to C++

Assumption:

• the function must be some how polymorphic to make it usable from python
• I assume that it constructs a GridViewFunction
• The C++ function should then accept a GridViewFunction and work with this...