#include <iostream>
#include <functional>

template<typename Ret, typename ...Params>
Ret call_it(Params... param, void*object)
{
    std::function<Ret(Params...)> *fun = reinterpret_cast<std::function<Ret(Params...)>*>(object);

    return (*fun)(param...);
}

template<typename Ret, typename ...Params>
auto convert_it(std::function<Ret(Params...)> const&) -> Ret(*)(Params...,void*)
{
    return &call_it<Ret,Params...>;
}

void needs_a_void_int(void (*fun)(int,void*), void *object)
{
    fun(123,object);
}


void needs_a_int_int_int(int (*fun)(int, int,void*), void *object)
{
    std::cout << fun(123,231,object) << std::endl;
}

class Example
{
public:
    void bla(int x)
    {
        std::cout <<__FUNCTION__ << ' '<< x << std::endl;
    }
int plus(int y, int x)
    {
        std::cout <<__FUNCTION__ << y << '+'<< x << std::endl;
        return x+y;
    }
};

int main()
{

    Example obj;
    std::function<void(int)>  bla = [&obj](int value)->void { obj.bla(value); };
    std::function<int(int,int)>  plus = [&obj](int v1, int v2)->int { return obj.plus(v1,v2); };

    needs_a_void_int(convert_it(bla), &bla);
    needs_a_int_int_int(convert_it(plus), &plus);
}