Design patterns learning - observer mode (c ++)

Description: This paper is the code. The main contents include the following three points.

First, the test function call

Second, the header file (.h) content

Third, the source code (.cpp) content

 

text

First, the test function call method

#include " observer.h " include headers // 
int main () 
{ 
    testObeserver (); // call the function is the main function test 
}

Test functions as follows:

void testObeserver () 
{ 
    the Sound * m = new new Music (); // add a song as the viewer 

    The Listener * = zhoujielun new new Funs ( " zhoujielun " ); // add four fans, as an observer 
    The Listener * = caiyilin new new Funs ( " caiyilin " ); 
    The Listener * = dongxiaojie new new Funs ( " dongxiaojie " ); 
    The Listener * = kunling new new Funs ( " kunling " ); 

    m -> the addListener (zhoujielun); // Register the observer
    m  ->the addListener (dongxiaojie); 
    m -> the addListener (caiyilin); 
    m -> the addListener (kunling); 

    m -> makeNoise ( " Hanada Rose " ); // broadcast viewer is issued 

    
    Delete m; m = nullptr a; 
    

}

Results of the:

 

Second, the header file (.h) content

. 1  #pragma Once
 2 #include " util.h " 
. 3 #include <List>
 . 4  
. 5  / * observation mode
 6  define dependencies between the subject an-many, when a state of the object changes,
 7  all it depends on the object to be notified and updated automatically.
. 8  
. 9  * / 
10  
. 11  
12 is  /////////////////////////////////////////// ///////////////////////////// // 
13  // is observer (Sound), a viewer (listener) 
14  
15  
16  
. 17  class Listener; // declare in advance class
 18  
19  // the observed abstract class 
20  classThe Sound
 21 is  {
 22 is  public :
 23 is      the Sound ();
 24      Virtual ~ the Sound ();
 25      Virtual  void the addListener (The Listener listener *) = 0 ; // registered observers 
26 is      Virtual  void removeListener (The Listener listener *) = 0 ;
 27      Virtual  void makeNoise ( const  String & Noise) = 0 ; // the broadcast message viewer 
28      
29  };
 30  
31 is  // is observer particular class 
32  class Music:public Sound
33 {
34 public:
35     Music();
36     ~Music();
37     void addListener(Listener* listener) override;
38     void removeListener(Listener* listener) override;
39     void makeNoise(const string& noise) override;
40 
41 private:
42     list<shared_ptr<Listener>> _listenerlist;
43 };
44 
45 //Abstract viewer 
46 is  class The Listener
 47  {
 48  public :
 49      The Listener ();
 50      Virtual ~ The Listener ();
 51 is      Virtual  void the listen ( const  String & Noise) = 0 ; // receiving a broadcast message viewer 
52 is      Virtual  void setListenerName ( const  String & name) = 0 ;
 53 is      Virtual  const  String & name () = 0 ;
 54 is  
55  };
 56 is  
57 is //观察者具体类
58 class Funs :public Listener
59 {
60 public:
61     Funs();
62     Funs(const string& name);
63     void listen(const string& noise) override;
64     void setListenerName(const string& name) override;
65     const string& name() override;
66 
67 private:
68     String the _name;
 69  };
 70  
71 is  // test 
72  void testObeserver ();

View Code

 

Third, the source code (.cpp) content

#include "pch.h"
#include "observer.h"

Sound::Sound(){}

Sound::~Sound(){}

Music::Music(){}

Music::~Music()
{
    _listenerlist.clear();
}

void Music::addListener(Listener * listener)
{
    shared_ptr<Listener> temp(listener);
    auto iter = find(_listenerlist.begin(), _listenerlist.end(), temp);
    if (iter == _listenerlist.end())
    {
        _listenerlist.push_front(temp);
    } 
    else
    {
        print("listener already exists");
    }
}

void Music::removeListener(Listener * listener)
{
    auto iter = _listenerlist.begin();
    for (;iter!=_listenerlist.end();iter++)
    {
        if ((*iter).get()==listener)
        {
            _listenerlist.erase(iter);
            return;
        }
        
    }
}

void Music::makeNoise(const string& noise)
{
    //notify listeners
    auto iter = _listenerlist.begin();
    for (;_listenerlist.end()!=iter;iter++)
    {
        (*iter).get()->listen(noise);
    }
}

Listener::Listener(){}

Listener::~Listener(){}

Funs::Funs():_name("unknown"){}

Funs::Funs(const string & name):_name(name){}

void Funs::listen(const string & noise)
{
    print(this->name().data());
    print("listened ");
    print(noise.data());
}

void Funs::setListenerName(const string & name)
{
    _name = name;
}

const string & Funs::name()
{
    return _name;
}


void testObeserver()
{
    Sound* m = new Music();

    Listener* zhoujielun = new Funs("zhoujielun");
    Listener* caiyilin = new Funs("caiyilin");
    Listener* dongxiaojie = new Funs("dongxiaojie");
    Listener* kunling = new Funs("kunling");

    m->addListener(zhoujielun);
    m->addListener(dongxiaojie);
    m->addListener(caiyilin);
    m->addListener(kunling);

    m->makeNoise("花田玫瑰");

    
    delete m; m = nullptr;
    

}

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