// Example program
#include <iostream>
#include <string>

class Notification
{
    public:
    virtual void notify(std::string mSubject)=0;

};

class WAppNotification : public Notification
{
    public:
    void notify (std::string mSubject) override
    {
         std::cout << "Whatsapp " << mSubject << "\n";
    }
};

class MailNotification : public Notification
{
    public:
    void notify (std::string mSubject) override
    {
        std::cout << "Mail " << mSubject << "\n";
    }
};

class User
{
private:
    Notification * _notification;

public:
    User()
    {
        _notification = new MailNotification();
    }
    ~User()
    {
        delete(_notification);
    }

    void send(std::string mSubject)
    {
        //Solo envia las notificaciones bien a Mail
        _notification->notify(mSubject);
    }

    void setWAppNotification()
    {
        // Borro el _notification -> Ahora era de Type MailNotification()
        delete(_notification);
        Notification * n;
        n = new WAppNotification();
        // Aqui quiero asignar a Notification *_notification el Type WAppNotification()
        setNotificationType(n);
    }

    void setNotificationType (Notification * mNotification)
    {
        _notification = mNotification;
    }
};

int main()
{
   User user;

   user.send("primer mensaje");
   user.setWAppNotification();
   user.send("segundo mensaje");
}