The Pwned Combinator

pwned_combinator.cpp

/* 
  The Pwned Combinator is a patten which gives you the ability to store a common base for templated classes in a container 
  while not losing the ability to access the member variables and functions of the derived instance.

  In this pattern, the base class uses polymorphism to signal usage which then triggers the callable.
*/

struct Base
{
  virtual void use()= 0;
  virtual ~Base(){}
};

#include <functional>

template <typename T>
struct Derived: Base
{
  typedef std::function<void(Derived &)> Signal;
  T data;
  Signal signal;

  Derived(T const &data)
  : data(data)
  {}

  void use(){ signal(*this); }
};

#include <vector>
#include <iostream>

int main()
{
  std::vector<std::reference_wrapper<Base>> objects;
  Derived<int> d1(42);
  Derived<std::string> d2("omg");

  d1.signal= [](Derived<int> &d){ std::cout<< "d1's data: "<< d.data<< '\n'; };
  objects.push_back(d1);

  d2.signal= [](Derived<std::string> &d){ std::cout<< "d2's data: "<< d.data<< '\n'; };
  objects.push_back(d2);

  objects[0].get().use();
  objects[1].get().use();
};