wrapping a std::function as class member

I got stuck completly with the following, when trying to wrap a class with a std::function member.
The following code produces an error inside pybind11.h.
Obviously, something goes wrong with a std::function object as a class member.

Binding Code:

#include <pybind11/pybind11.h>
#include <pybind11/functional.h>
#include "pyBind11Test.hpp" 

namespace py = pybind11;

PYBIND11_MODULE(stuff, module) {
      
   py::class_<Stuff> (module, "Stuff")
      .def( py::init( []
                      (const int n)
                      {return std::unique_ptr<Stuff> (new Stuff(n)); } ))
      .def("getNr", &Stuff::getNr);
}

Class declaration pyBind11Test.hpp

#include <iostream>
#include <functional>

class Stuff {
   private:
      double retOne();
      double retTwo();
   public:
      Stuff(const int n);
      std::function<double()> getNr;
};

Class definition pyBind11Test.cpp

#include "pyBind11Test.hpp"

Stuff::Stuff(const int n) {
   switch(n) {
      case 1 : {
         std::function<double()> getNr = [this](){return this->retOne();};
      }
      case 2 : {
         std::function<double()> getNr = std::bind(&Stuff::retTwo, this);
         // std::function<double()> getNr = [this](){return this->retTwo();};
      }
      default : {
         exit(1);
      }
   }
}

double Stuff::retOne(){
   return 1.;
}

double Stuff::retTwo(){
   return 2.;
}

The compiler terminates withe the following error message:

g++ -std=c++14 -fPIC -Wall -I/usr/include/python3.5m -I/usr/local/include/python3.5 -I/usr/include -o ./wrapPyBind11Test.o -c ./wrapPyBind11Test.cpp

In file included from ./wrapPyBind11Test.cpp:3:0:
/usr/local/include/python3.5/pybind11/pybind11.h: In instantiation of ‘pybind11::class_<type_, options>& pybind11::class_<type_, options>::def(const char*, Func&&, const Extra& ...) [with Func = std::function<double()> Stuff::*; Extra = {}; type_ = Stuff; options = {}]’:
./wrapPyBind11Test.cpp:22:36:   required from here
/usr/local/include/python3.5/pybind11/pybind11.h:1086:73: error: no matching function for call to ‘pybind11::cpp_function::cpp_function(std::function<double()> Stuff::*, pybind11::name, pybind11::is_method, pybind11::sibling)’
                         sibling(getattr(*this, name_, none())), extra...);
                                                                         ^
In file included from ./wrapPyBind11Test.cpp:3:0:
/usr/local/include/python3.5/pybind11/pybind11.h:78:5: note: candidate: template<class Return, class Class, class ... Arg, class ... Extra> pybind11::cpp_function::cpp_function(Return (Class::*)(Arg ...) const, const Extra& ...)
     cpp_function(Return (Class::*f)(Arg...) const, const Extra&... extra) {
     ^
/usr/local/include/python3.5/pybind11/pybind11.h:78:5: note:   template argument deduction/substitution failed:
In file included from ./wrapPyBind11Test.cpp:3:0:
/usr/local/include/python3.5/pybind11/pybind11.h:1086:73: note:   mismatched types ‘Return (Class::*)(Arg ...) const’ and ‘std::function<double()> Stuff::*’
                         sibling(getattr(*this, name_, none())), extra...);
                                                                         ^
In file included from ./wrapPyBind11Test.cpp:3:0:
/usr/local/include/python3.5/pybind11/pybind11.h:71:5: note: candidate: template<class Return, class Class, class ... Arg, class ... Extra> pybind11::cpp_function::cpp_function(Return (Class::*)(Arg ...), const Extra& ...)
     cpp_function(Return (Class::*f)(Arg...), const Extra&... extra) {
     ^
/usr/local/include/python3.5/pybind11/pybind11.h:71:5: note:   template argument deduction/substitution failed:
In file included from ./wrapPyBind11Test.cpp:3:0:
/usr/local/include/python3.5/pybind11/pybind11.h:1086:73: note:   mismatched types ‘Return (Class::*)(Arg ...)’ and ‘std::function<double()> Stuff::*’
                         sibling(getattr(*this, name_, none())), extra...);
                                                                         ^
In file included from ./wrapPyBind11Test.cpp:3:0:
/usr/local/include/python3.5/pybind11/pybind11.h:64:5: note: candidate: template<class Func, class ... Extra, class> pybind11::cpp_function::cpp_function(Func&&, const Extra& ...)
     cpp_function(Func &&f, const Extra&... extra) {
     ^
/usr/local/include/python3.5/pybind11/pybind11.h:64:5: note:   template argument deduction/substitution failed:
/usr/local/include/python3.5/pybind11/pybind11.h:57:5: note: candidate: template<class Return, class ... Args, class ... Extra> pybind11::cpp_function::cpp_function(Return (*)(Args ...), const Extra& ...)
     cpp_function(Return (*f)(Args...), const Extra&... extra) {
     ^
/usr/local/include/python3.5/pybind11/pybind11.h:57:5: note:   template argument deduction/substitution failed:
In file included from ./wrapPyBind11Test.cpp:3:0:
/usr/local/include/python3.5/pybind11/pybind11.h:1086:73: note:   mismatched types ‘Return (*)(Args ...)’ and ‘std::function<double()> Stuff::*’
                         sibling(getattr(*this, name_, none())), extra...);
                                                                         ^
In file included from ./wrapPyBind11Test.cpp:3:0:
/usr/local/include/python3.5/pybind11/pybind11.h:53:5: note: candidate: pybind11::cpp_function::cpp_function()
     cpp_function() { }
     ^
/usr/local/include/python3.5/pybind11/pybind11.h:53:5: note:   candidate expects 0 arguments, 4 provided
/usr/local/include/python3.5/pybind11/pybind11.h:51:7: note: candidate: pybind11::cpp_function::cpp_function(const pybind11::cpp_function&)
 class cpp_function : public function {
       ^
/usr/local/include/python3.5/pybind11/pybind11.h:51:7: note:   candidate expects 1 argument, 4 provided
/usr/local/include/python3.5/pybind11/pybind11.h:51:7: note: candidate: pybind11::cpp_function::cpp_function(pybind11::cpp_function&&)
/usr/local/include/python3.5/pybind11/pybind11.h:51:7: note:   candidate expects 1 argument, 4 provided
makefile:24: recipe for target 'wrapPyBind11Test.o' failed
make: *** [wrapPyBind11Test.o] Error 1

Any ideas?

Start by reproducing the compiler error from the binding code and inspect the member declaration in pyBind11Test.hpp, the constructor in pyBind11Test.cpp, and the reported overloads in pybind11.h. Determine whether the failure is caused by binding a std::function data member or by the example itself; done means documenting a confirmed cause and a focused resolution or limitation.