#include <list>
#include <memory>
#include <iostream>
 
struct Base
{
   virtual void foo() = 0;
};
 
struct Derived1 : Base
{
   void foo() { std::cout << "Lol!\n"; }
};
 
struct Derived2 : Base
{
   void foo() { std::cout << "Haha!\n"; }
};
 
int main()
{
   typedef std::list<std::unique_ptr<Base>> list_type;
 
   list_type l;
   l.push_back(list_type::value_type(new Derived1()));
   l.push_back(list_type::value_type(new Derived2()));
   l.push_back(list_type::value_type(new Derived2()));
   l.push_back(list_type::value_type(new Derived1()));
 
   for (auto& x : l)
      x->foo();
}

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