subject.cpp

#include <map>
#include <functional>
#include "sub_token.h"

using namespace std::placeholders;
using namespace std;

template <typename... Args>
class subject
{
  public:
    void notify(Args... arg)
    {
        for (auto &kv : _map)
        {
            kv.second(arg...);
        }
    }

    sub_token subscribe(function<void(Args...)> fn)
    {
        sub_token tk;
        _map[tk] = fn;
        return tk;
    }

    void unsubscribe(sub_token tk)
    {
        _map.erase(_map.find(tk));
    }

  private:
    map<sub_token, function<void(Args...)>> _map;
};