[OOD] Prototype design pattern with CRTP usage

crtpClone.cpp

//
// author: Mateusz Pusz
//

#include <memory>

template<typename T, typename ...Args>
inline std::unique_ptr<T> make_unique(Args&&... args)
{
  return std::unique_ptr<T>(new T{std::forward<Args>(args)...});
}


class CProtectedCopyable {
protected:
  CProtectedCopyable(const CProtectedCopyable&) = default;
public:
  CProtectedCopyable() = default;
};


class CProduct : CProtectedCopyable {
public:
  virtual ~CProduct() {}
  virtual std::unique_ptr<CProduct> Clone() const = 0;
};

template<typename T>
class CProductCRTP : public CProduct {
public:
  virtual std::unique_ptr<CProduct> Clone() const { return make_unique<T>(static_cast<const T&>(*this)); }
};


// ----------------- HUGE CLASS HIERARCHY -------------------

class CProductWheelLoader : public CProductCRTP<CProductWheelLoader> {};
class CProductBulldozer   : public CProductCRTP<CProductBulldozer> {};
class CProductBackhoe     : public CProductCRTP<CProductBackhoe> {};

// .....................................


int main()
{
  CProductWheelLoader loader;
  CProduct &product = loader;
  auto copy = product.Clone();
}