11.9 VirtualCopyConstructors.cpp

#include <iostream>
using namespace std;

class Fish
{
public:
   virtual Fish* Clone() = 0;
   virtual void Swim() = 0;
   virtual ~Fish() {};
};

class Tuna: public Fish
{
public:
   Fish* Clone() override
   {
      return new Tuna (*this);
   }

   void Swim() override final
   {
      cout << "Tuna swims fast in the sea" << endl;
   }
};

class BluefinTuna final:public Tuna
{
public:
   Fish* Clone() override
   {
      return new BluefinTuna(*this);
   }

   // Cannot override Tuna::Swim as it is "final" in Tuna
};

class Carp final: public Fish
{
   Fish* Clone() override
   {
      return new Carp(*this);
   }
   void Swim() override final
   {
      cout << "Carp swims slow in the lake" << endl;
   }
};

int main()
{
   const int ARRAY_SIZE = 4;

   Fish* myFishes[ARRAY_SIZE];
   myFishes[0] = new Tuna();
   myFishes[1] = new Carp();
   myFishes[2] = new BluefinTuna();
   myFishes[3] = new Carp();

   Fish* myNewFishes[ARRAY_SIZE];
   for (int index = 0; index < ARRAY_SIZE; ++index)
      myNewFishes[index] = myFishes[index]->Clone();

   // invoke a virtual method to check
   for (int index = 0; index < ARRAY_SIZE; ++index)
      myNewFishes[index]->Swim();

   // memory cleanup
   for (int index = 0; index < ARRAY_SIZE; ++index)
   {
      delete myFishes[index];
      delete myNewFishes[index];
   }

   return 0;
}