text: #pragma once
  #include "ObserverMaster.h"
  class ObserverMaster;
  class Message;
  class Observer
  {
  private:
  	ObserverMaster* m_master;
  public:
  	virtual void OnSubscribe(ObserverMaster* obsMaster) { m_master = obsMaster; };
  	virtual void OnUnsubscribe() { m_master = nullptr; };
  	virtual void OnNotify(Message msg) = 0;
  };
  