#include #include using namespace std; // this is the one which gets observed by the others class Mothership{ vector notifyList; public: /* Observer setup ---------------------------------*/ void addShip(Fleet* observer) { notifyList.push_back(observer); } void notifyShips(); /*-----end observer setup-----*/ // actual class methods void setHealth(int newHealth) { health = newHealth; notifyShips(); } int getHealth() { return health; } private: int health = 100; }; // these are the observers which observe the mothership class Fleet { Mothership* model; public: /* The constructor adds the newly created objects into the notification vector of the observed mothership*/ Fleet(Mothership* mod) { model = mod; model->addShip(this); mothershipHealth = model->getHealth(); static int id = 1; shipID = id++; } virtual void update() = 0; virtual int getID() { return shipID; } virtual void setHealth(int newHealth) = 0; virtual int getHealth() = 0; protected: Mothership* getMothership() { return model; } private: int health = 100; int mothershipHealth; int shipID; }; void Mothership::notifyShips() { for (unsigned int i = 0; i < notifyList.size(); i++) { notifyList[i]->update(); } } class Battleship : public Fleet { public: Battleship(Mothership* mod) : Fleet(mod) {} void setHealth(int newHealth) { health = newHealth; } int getHealth() { return health; } void update(); private: int healthMothership; int health = 100; }; void Battleship::update() { if (getMothership()->getHealth() < 100 && getMothership()->getHealth() >= 30) { cout << "Battleship #" << this->getID() << ": " << "Mothership in danger! Help needed! Change destination!" << endl; } else if (getMothership()->getHealth() > 0 && getMothership()->getHealth() < 30) { cout << "Battleship #" << this->getID() << ": " << "Hurry up! Mothership nearly destroyed!" << endl; } else if (getMothership()->getHealth() == 0) { cout << "Battleship #" << this->getID() << ": " << "Mothership destroyed... we lost this battle..." << endl; } healthMothership = getMothership()->getHealth(); } int main() { //create the fleet Mothership testMothership; Battleship testBattleship1(&testMothership); Battleship testBattleship2(&testMothership); Battleship testBattleship3(&testMothership); Battleship testBattleship4(&testMothership); //testing observation cout << ">Mothership starts with 100 HP<" << endl << endl; cout << ">Set mothership HP to 80<" << endl; testMothership.setHealth(80); cout << endl; cout << ">Set mothership HP to 25<" << endl; testMothership.setHealth(25); cout << endl; cout << ">Destroy the mothership<" << endl; testMothership.setHealth(0); }

observer implementation