#include <iostream>
#include <string>
#include <boost/function.hpp>
#include <boost/any.hpp>

class X {
  public:
    std::string text() {   return std::string("hello world!"); }
};

class Y {
  public:
    int value() { return 5; }
};

class Z {
  public:
    bool isEnabled() { return true; }
};

// [...]
// There could be hundreds of classes like X, Y and Z

int main() {

  {
  boost::function<boost::any (X*)> f;
  f=&X::text;
  
  X x;
  std::cout << "x.text() is " << x.text() << std::endl;
  std::cout << "f(&x) is " << boost::any_cast<std::string>(f(&x)) << std::endl;
  }
  
  {  
  boost::function<boost::any (Y*)> f;
  f=&Y::value;
  
  Y y;
  std::cout << "y.value() is " << y.value() << std::endl;
  std::cout << "f(&y) is " << boost::any_cast<int>(f(&y)) << std::endl;
  }

  {  
  boost::function<boost::any (Z*)> f;
  f=&Z::isEnabled;
  
  Z z;
  std::cout << "z.isEnabled() is " << z.isEnabled() << std::endl;
  std::cout << "f(&z) is " << boost::any_cast<bool>(f(&z)) << std::endl;
  }
  
  
  return 0;
}