Class App

example/polymorphism/templates.cpp:14–21

/*<<Static polymorphism - templates>>*/
template <typename TDrawable = class Drawable>
class App {
 public:
  explicit App(const TDrawable drawable) : drawable(drawable) {}
  void draw(std::ostream& out) const { drawable.draw(out); }

 private:
  const TDrawable drawable;
};

struct Square {
  void draw(std::ostream& out) const { out << "Square"; }