C++: Observer pattern in C++

Goals:

1. no inheritance needed for observers and subjects.
2. provide a uniform interface with sufficient flexibility on parameter types.
3. no RTTI needed for casting parameters.

repository: https://github.com/toliuweijing/ObserverPatternInCPP

#include
#include "wl/Subject.hpp"
using namespace wl;
using namespace std;

struct FireEvent {
    string location;
    int level;
};

class FireDepartment {
public:
    void response(FireEvent fire_event) {
        cout << "A level " << fire_event.level <<
            " fire at " << fire_event.location << endl;
        cout << "On my way" << endl;
    }
};

class SecuritySystem {
public:
    Subject fire_alarm;
};

int main(int argc, const char *argv[]) {
    SecuritySystem sys;
    FireDepartment dep;

    sys.fire_alarm += wl::bind(&dep, &FireDepartment::response);
    sys.fire_alarm(FireEvent{"NYC", 100000});
    return 0;
}

• C++
• delegate