How can I redesign these classes to take advantage of interfaces?

Question

I'm writing a card game (Dominion) as a pet project. I'm new to C++ but not programming.

A player has a deck, containing the hand and cards in play (tableau). Outside the player, there are piles of cards to buy from (supply piles). I want to display these objects (the hand, tableau and supply piles) on the screen. I had chosen to represent the hand and tableau using std::vector<Card> and the supply piles as std::vector<SupplyPile>. Card and SupplyPile implement an interface for displaying contents to the screen

class IInfo {
public:
  virtual std::string Info() const = 0;
  virtual std::string ToString() const = 0;
};

I have a class I'm calling View that will take on displaying things to the screen.

class View {
public:
  View(const std::vector<IInfo*>& items, int window_starty, int window_startx);
  virtual ~View() { }

  const IInfo& CurrentItem() const;
  const int CurrentIndex() const;
  bool IsEmpty() const;
  void ItemDown();
  void ItemUp();
  void SetActive();
  void SetInactive();
  virtual void Update();
protected:
  virtual WINDOW* InitializeWindow(int lines,
    int cols,
    int starty,
    int startx);

  virtual ITEM** MakeMenuItems();
private:
  // Some constants

  const std::vector<IInfo*>& items_;

  MENU *menu_;
  WINDOW *window_;
};

I now know that C++ doesn't support covariance in templates, so I can't create instances of View with the supply pile, hand, and tableau. How can I redesign the system to maximize DRY? The View class operates on its container member in a very simple way, ripe for abstraction.

Examples of things I want to do

std::vector<Card> hand = player.hand();
std::vector<Card> tableau = player.tableau();
std::vector<SupplyPile> supply_piles = game.supply_piles();

View hand_view = new View(hand, starty, startx);
View tableau_view = new View(tableau, starty, startx);
View supply_piles_view = new View(supply_piles, starty, startx);

One answer suggested making View into a template, and it almost worked until I remembered that I want to track which View is active at a given time:

View active_ = hand_view;
// Later
active_ = supply_piles_view;

I can't do this with View<Card> and View<SupplyPile>.

Other code

class Card : public IInfo {
public:
  Card(std::string name,
    int cost,
    int initial_supply,
    std::string text,
    std::string type);
  ~Card();

  void Play();
  std::string Info() const;
  std::string ToString() const;

  int cost() const;
  int initial_supply() const;
  std::string name() const;
  std::string text() const;
private:
  int cost_;
  int initial_supply_;

  std::string name_;
  std::string text_;
  std::string type_;

  std::string set_;
};

class SupplyPile : public IInfo {

public:
    SupplyPile(const Card& card, int initial_count);
    SupplyPile(const SupplyPile& other);
    virtual ~SupplyPile();
    virtual bool operator==(const SupplyPile& other) const;

    bool BuyOrGain();
    std::string Info() const;
    std::string ToString() const;

    const Card& card() const;
    int count() const;
    std::string name() const;
private:
    const Card& card_;

    int count_;
};

Answer 1

Is there any reason why View itself can't be a template?

template <typename T> class View {
public:
  View(const std::vector<T>& items, int window_starty, int window_startx);
  virtual ~View() { }

  const T& CurrentItem() const;
  // ...
  const std::vector<T>& items_;
  // ...
};

View<Card> hand_view = new View<Card>(hand, starty, startx);

Answer 2

I ended up doing something I don't much like, but it works.

I redesigned View to work with disposable copies of a new interface, IViewable. IViewable will be the link between the UI and the core logic. Every time a UI update is needed, copies of the items to display will be passed as std::vector<IViewable*>.

The new View ctor is:

  View(std::vector<IViewable*> *initial_items, int window_starty, int window_startx)

Updates need a new set of items to display each time, rather than using a reference to the originals like I wanted:

  void Update(std::vector<IViewable*> *items);