ROS generic subscriber as a class method

edit

Here I am trying this example's subscriber example code from facontidavide and it works fine as it is. However when I put the topicCallback() in a Class, it's instances appear to share its global variables - whether they are public or private.

class Foo{
private:
    std::string _topic;
public:
    Foo(std::map <std::string, std::string>& info)
    {
        _topic = info["topic"];
    };
    void topicCallback(const topic_tools::ShapeShifter::ConstPtr& msg,
                   const std::string &topic_name,
                   RosIntrospection::Parser& parser)
    {
        ---EXAMPLE CODE---
        cout << _topic << endl;
    }
}

main(){
    ---SOME CODE---
    for (auto &info : topics)
    {
        Foo f(info);
        boost::function<void(const topic_tools::ShapeShifter::ConstPtr&) > callback;
        callback = [&parser, &info, &f](const topic_tools::ShapeShifter::ConstPtr& msg)->void
        {
            f.topicCallback(msg, info.at("topic"), parser) ;
        };
        subscribers.push_back( nh.subscribe(info["topic"], 10, callback) );
    }
    ---SOME MORE CODE---
}

When I create several instances of the class and subscribe to the callback just as in the example code, _topic appears to be the same for all instances. Actually it is the topic of the last instance I create.

This probably might be due to my little understanding of C++11. It'd be a great help if someone could point out what I am doing wrong here.

Edit: Yes it is a C++ related question. But I don't think I'll get an answer by asking this on stackoverflow. I tried using boost::bind instead using a lambda. But it gives some unrecognizable errors like error: use of deleted function xxx May be due to the callback expecting a topic_tools::ShapeShifter for all message types?