Observer pattern in C++11

observer.cpp

//
//  main.cpp
//  Observer pattern in C++11
//
//  Created by Morten Nobel-Jørgensen on 9/21/12.
//  Copyright (c) 2012 Morten Nobel-Joergensen. All rights reserved.
//

#include <iostream>


using namespace std;
using namespace std::placeholders;

#include <iostream>
#include <functional>
#include <vector>

class Foo {
public:
    void addValueListener(std::function<void (Foo*)> listener){
        valueListeners.push_back(listener);
    }
    void removeValueListener(std::function<void (Foo*)> listener){
        // ....
    }

    void setValue(int value){
        if (value != this->value){
            this->value = value;
            fireValueUpdated();
        }
    }
    int getValue(){
        return value;
    }
private:
    void fireValueUpdated(){
        for (auto &f:valueListeners) {
            f(this);
        }
    }
    int value;
    std::vector<std::function<void (Foo*)>> valueListeners;
};

class Moo {
public:
    Moo(std::string s):s(s) {}
    void FooUpdated(Foo *f){
        std::cout << s<< " saw foo value updated to " << f->getValue() << std::endl;
    }
private:
    std::string s;
};

int main(int argc, const char * argv[])
{
    Foo f;
    f.setValue(123);
    f.addValueListener([] (Foo *f){
        cout << "New Foo value "<<f->getValue()<<endl;
    });
    f.setValue(124);
    Moo m("Moo#1");
    f.addValueListener([&m](Foo *f){m.FooUpdated(f);});
    f.setValue(125);
    Moo m2("Moo#2");
    f.addValueListener(bind(&Moo::FooUpdated,m2, _1));
    f.setValue(126);
    return 0;
}