// Tcloner.cpp

#include <string>
#include <iostream>

template <typename T>
class cloner
{
public:
  virtual ~cloner() {}
  virtual T* clone() const=0;
};

class base : public cloner<base>
{
public:
  base(const std::string& msg) : _msg(msg) {}
  virtual ~base() {}
  virtual void say()=0;
protected:
  std::string _msg;
};

class derived1 : public base
{
public:
  derived1(const std::string& msg) : base(msg) {}
  base* clone() const { return new derived1(*this); }
  void say() { std::cout << "\n  derived1: " << _msg; } 
};

class derived2 : public base
{
public:
  derived2(const std::string& msg) : base(msg) {}
  base* clone() const { return new derived2(*this); }
  void say() { std::cout << "\n  derived2: " << _msg; } 
};

int main()
{
  base* originals[2] = 
  { 
    new derived1("Hi from 1"), new derived2("Hi from 2") 
  };

  base* clones[2];

  for(int i=0; i<2; ++i)
  {
    clones[i] = originals[i]->clone();
    delete originals[i];
  }
  for(int i=0; i<2; ++i)
  {
    clones[i]->say();
    delete clones[i];
  }
 
  std::cout << "\n\n";
}