Design mode (10)--Viewer mode

10. Observer mode//ver1class Stockobserver; interdependence with Secretary; So in advance declare class secretary;//stock colleague Class stockobserver{private:string _name; Secretary * _ps;public:stockobserver (string name, Secretary *p) {_name = Name;_ps = P;} void Update () {//Get a notification from the front desk and take action quickly. _ps->getsecretaryaction (); must be shielded here; There is no way to compile the pass, Stockobserver and secretary are mutually coupled. The solution is to write in 2. h and. cpp files, respectively. In the. h file, declare the class to be referenced in advance and define the object as a pointer. }};//Front desk Secretary class Secretary{private:list<stockobserver *> mylist;string _action;public://add void Attach ( Stockobserver * psob) {mylist.push_back (PSOB);} reduce void Detach (Stockobserver * psob) {mylist.remove (PSOB);} notify void Notify () {list<stockobserver *>::iterator it = Mylist.begin (); for (; It! = Mylist.end (); ++it) {(*it)->u Pdate ();}} foreground state void Setsecretaryaction (string stract) {_action = stract;} String Getsecretaryaction () {return _action;}}; void Main1 () {secretary *ps1 = new Secretary (); Stockobserver *pso1 = new Stockobserver ("Fun", PS1); Stockobserver *PSO2 = new Stockobserver ("Test", PS1);//foreground note two colleagues Ps1-> Attach ((PSO1));p S1->attach ((PSO2));//The Boss came back, sent notice ps1->setsecretaryaction ("The Boss came Back");p s1->notify ();}

 

10. Observer mode//ver2//observer.h//pre-declaration class Subject; Class Boss;class Secretary;class observer{protected:string _name; Subject * _ps;public:observer (string name, Subject * PS), virtual ~observer (void);p ublic:virtual void Update ();};/ /See Stock colleague Class Stockobserver:public Observer{public:stockobserver (string name, Subject * PS); virtual ~stockobserver (); virtual void Update ();};/ /See NBA colleague Class Nbaobserver:public Observer{public:nbaobserver (string name, Subject * PS); virtual ~nbaobserver (); virtual void Update ();};/ /observer.cpp#include "Observer.h" #include "Secretary.h" Observer::observer (string name, Subject * PS) {_ps = Ps;_name = Name;} Observer::~observer (void) {}void observer::update () {_ps->getsecretaryaction ();} Stockobserver::stockobserver (string name, Subject * PS): Observer (name, PS) {}stockobserver::~stockobserver () {}void Stockobserver::update () {_ps->getsecretaryaction ();} Nbaobserver::nbaobserver (string name, Subject * PS): Observer (name, PS) {}nbaobserver: :~Nbaobserver () {}void nbaobserver::update () {_ps->getsecretaryaction ();} -----------------------------------//subject.h//Pre-declaration class Observer;class Stockobserver;class nbaobserver;// Notifier interface class subject{public:virtual void Attach (Observer *pob); virtual void Detach (Observer *pob); virtual void Notify (); void Setsecretaryaction (String stract); string getsecretaryaction ();};/ /Boss Notifier class Boss:public subject{private:list<observer*> mylist;string _action;public:void Attach (Observer *pob void Detach (Observer *pob); void Notify (); void Setsecretaryaction (String stract); string getsecretaryaction ();}; Class secretary{private:list<observer*> mylist;string _action;public://add void Attach (Observer * pob);//decrease void Detach (Observer * pob);//notification void Notify ();//foreground State void Setsecretaryaction (string stract); string getsecretaryaction ();};/ /subject.cpp#include "Secretary.h" #include "Observer.h" void Subject::attach (Observer *pob) {}void Subject::D Etach ( Observer *pob) {}void subject::notify () {}void subject::sEtsecretaryaction (String stract) {}string subject::getsecretaryaction () {return "";} void Boss::attach (Observer *pob) {mylist.push_back (POB);} void Boss::D etach (Observer *pob) {mylist.remove (POB);} void Boss::notify () {list<observer *>::iterator it = Mylist.begin (); for (; It! = Mylist.end (); ++it) {(*it)-&GT;UPDA Te ();}} void Boss::setsecretaryaction (String stract) {_action = stract;} String Boss::getsecretaryaction () {return _action;} void Secretary::attach (Observer * pob) {mylist.push_back (POB);} Reduced void Secretary::D Etach (Observer * pob) {mylist.remove (POB);} notify void Secretary::notify () {list<observer *>::iterator it = Mylist.begin (); for (; It! = Mylist.end (); ++it) {(*it) ->update ();}} foreground state void Secretary::setsecretaryaction (string stract) {_action = stract;} String Secretary::getsecretaryaction () {return _action;} -----------------//main.cpp#include "Secretary.h" #include "Observer.h" int main () {//boss bosses *pboss = new boss ();// See Stock colleague Stockobserver *ptongshi1= new Stockobserver ("Fun", pboss);//Watch NBA colleague Nbaobserver *ptongshi2 = new Nbaobserver ("Test", Pboss);p Boss->attach ( PTONGSHI1);p Boss->attach (pTongshi2);p Boss->detach (PTONGSHI1);//The Boss came back Pboss->setsecretaryaction (" I'm the boss and I'm back! "); /give notice pboss->notify (); return 0;}

　

Design mode (10)--Viewer mode