Design pattern--observer pattern observer (object behavior type)

First, the Observer pattern

The Observer pattern is to define a one-to-many dependency between objects, so that when an object changes state, the objects that depend on it are notified and updated automatically. The observer pattern is also called: Subject-Viewer mode, publish-subscribe mode, the former is one, the latter is more.

Second, UML class diagram

Iii. examples

//observersclassObserver { Public: Observer () {}Virtual~Observer () {}Virtual voidUpdate () {}};//BlogclassBlog { Public: Blog () {}Virtual~Blog () {}voidAttach (Observer *observer) {m_observers.push_back (Observer);}//Add Observer    voidRemove (Observer *observer) {m_observers.remove (Observer);}//removing observers    voidNotify ()//notify the viewer{List<observer*>::iterator iter =M_observers.begin ();  for(; ITER! = M_observers.end (); iter++)            (*iter)Update (); }    Virtual voidSetStatus (strings) {m_status = s;}//Set Status    Virtual stringGetStatus () {returnM_status; }//Get StatusPrivate: List<observer* > M_observers;//Observer linked listprotected:    stringM_status;//Status};//Specific Blog CategoriesclassBLOGCSDN: Publicblog{Private:    stringM_name;//Bo Master Name Public: Blogcsdn (stringname): M_name (name) {}~blogcsdn () {}voidSetStatus (strings) {m_status ="CSDN Notice:"+ M_name + S; }//setting state information specifically    stringGetStatus () {returnm_status;}};//specific observersclassObserverblog: PublicObserver {Private:    stringM_name;//Viewer NameBlog *m_blog;//Watch the blog, of course, in a list form better, you can observe multiple blogs Public: Observerblog (stringName,blog *blog): M_name (name), M_blog (blog) {}~Observerblog () {}voidUpdate ()//Get update Status    {         stringStatus = M_blog->GetStatus (); cout<<m_name<<"-------"<<status<<Endl; }};//Test CaseintMain () {Blog*blog =NewBLOGCSDN ("wuzhekai1985"); Observer*observer1 =NewObserverblog ("Tutupig", blog); Blog-Attach (Observer1); Blog->setstatus ("Publish design Pattern C + + implementation (15)--Observer mode"); Blog-Notify (); DeleteBlogDeleteObserver1; return 0;}

Design pattern--observer pattern observer (object behavior type)