#include <functional>
#include <iostream>
#include <string>

int main()
{
  auto f = std::mem_fn(&std::string::size);
	
  std::string woerter[] = { "Ein", "Test" };
  for(auto e : woerter)
  {
    std::cout << e << " : " << f(e) << '\n';
  }
  
  // === überladene Methoden mit cast spezifiziert:
  
  // std::string& (std::string::*member)(const std::string&)> = 
  auto member = 
    static_cast<std::string& (std::string::*)(const std::string&)>(&std::string::append);

  auto fn = std::mem_fn(member);

  // std::function<std::string&(std::string&)> 
  auto binder = std::bind(fn, std::placeholders::_1, " and bind");

  // === bind() auch ohne mem_fn() möglich:
  
  // std::function<std::string&(std::string&, const std::string&)> 
  auto binder2 = std::bind(member, std::placeholders::_1, std::placeholders::_2);

  // === oder Lambda-Ausdruck:
		
  auto lambda = [](std::string& s, const std::string& appendix) 
    -> std::string& 
    {
      return s.append(appendix);
    };
  // trailing return type needed here, otherwise std::function<> cannot resolve
	
  // std::function<std::string&(std::string&, const std::string&)> 
  auto f = std::function<std::string&(std::string&, const std::string&)>(lambda);

  std::string s = "Hello";
  (s.*member)(" world");
  fn(s, " of mem_fn");
  binder(s);
  binder2(s, " with placeholders"); 	
  lambda(s, " or lambda");
  f(s, " as function");
	
  std::cout << s << '\n';
}