#include #include #include using namespace std; class parents { public: virtual void notify() = 0; ~parents() {cout << "Parent de-allocated\n";} }; class father : public parents { public: ~father() {cout << "Father de-allocated\n";} void run(){cout << "Father runs and reaches to son : ";} void notify() { run(); cout << "Oops my son...! you father is here to help you...!\n"; } }; class mother : public parents { public: ~mother() {cout << "Mother de-allocated\n";} void run(){cout << "Mother runs and reaches to son : ";} void notify() { run(); cout << "Oops my son...! you mother is here to help you...!\n"; } }; class child { list> lstObservers; public: void gotInjured() { cout << "I got injured\n"; for (auto observer : lstObservers) { observer->notify(); } } void addObserver(shared_ptr p) { lstObservers.push_back(p); } void removeObserver(shared_ptr p) { lstObservers.remove(p); } }; int main() { child objChild; shared_ptr papa = make_shared(); shared_ptr mom = make_shared(); objChild.gotInjured(); cout << endl << endl; cout << "-------->Now adding mom and papa as observers" << endl; objChild.addObserver(papa); objChild.addObserver(mom); objChild.gotInjured(); cout << endl << endl; cout << "-------->Now removing papa as observers" << endl; objChild.removeObserver(papa); objChild.gotInjured(); cout << endl << endl; return 0; }

Observer_RealLifeExample