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Subject.h

#ifndef SUBJECT_H
#define SUBJECT_H

#include <list>
#include "Observer.h"
using namespace std;

class Subject {
  public:
    virtual ~Subject();  
    virtual void attach(Observer *const);
    virtual void detach(Observer *const);
    virtual void detachAllObservers();
    virtual void notify() const;
  protected:
    Subject() {}
  private:
    std::list<Observer *> _observers;
};



//  Implementations of the methods that are not pure virtual.

inline Subject::~Subject() {
  _observers.clear();
}

inline void Subject::attach(Observer *const o) {
  _observers.push_back(o);
}

inline void Subject::detach(Observer *const o) {
  _observers.remove(o);
}

inline void Subject::detachAllObservers() {
 _observers.clear();
}

inline void Subject::notify() const {
  for (std::list<Observer *>::const_iterator i = _observers.begin();
       i != _observers.end();
       ++i) {
    (*i)->update(this);
  }
}

#endif

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