Observer design pattern in C++

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礼貌的吻别 2020-12-06 03:00

Is the observer design pattern already defined in STL (Like the java.util.Observer and java.util.Observable in Java) ?

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死守一世寂寞 (楼主)

2020-12-06 03:56

Here is a reference implementation (from Wikipedia).

#include 
#include 
#include 
#include 

class SupervisedString;
class IObserver{
public:
    virtual void handleEvent(const SupervisedString&) = 0;
};


class SupervisedString{ // Observable class
    std::string _str;
    std::map _observers;

    typedef std::map::value_type item;

    void _Notify(){
        BOOST_FOREACH(item iter, _observers){
            iter.second->handleEvent(*this);
        }
    }

public:
    void add(IObserver& ref){
        _observers.insert(item(&ref, &ref));
    }

    void remove(IObserver& ref){
        _observers.erase(&ref);
    }

    const std::string& get() const{
        return _str;
    }

    void reset(std::string str){
        _str = str;
        _Notify();
    }
};


class Reflector: public IObserver{ // Prints the observed string into std::cout
public:
    virtual void handleEvent(const SupervisedString& ref){
        std::cout<