Observer of C++

//Observer

#include <list>

template <typename Event>
class IObserver {
public:
    virtual void Notify(Event& e) = 0;
};

template <typename Event>
class Observer {
typedef typename IObserver<Event> Interface;
private:
    std::list<Interface*> _observers;
public:
    Observer() {}
    virtual ~Observer() {
        deleteObservers();
    }

    void HookObserver(Interface* pObj) {
        std::list<Interface*>::iterator iter = _observers.begin();
        while (iter != _observers.end()) {
            if ((*iter) == pObj) {
                return;
            }
        }
        _observers.push_back(pObj);
    }

    int countObservers() {
        return _observers.size();
    }

    void UnHookObserver(Interface* pObj) {
        std::list<Interface*>::iterator iter = _observers.begin();
        while (iter != _observers.end()) {
            if ((*iter) == pObj) {
                _observers.erase(iter);
                return;
            }
        }
    }

    void deleteObservers() {
        _observers.clear();
    }

    void Notify(Event& e) {
        std::list<Interface*>::iterator iter = _observers.begin();
        while (iter != _observers.end()) {
            (*iter)->Notify(e);
        }
    }
};