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Using Class Methods as Callbacks

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Subscriptions

Suppose you have a simple class, Listener:

https://raw.github.com/ros/ros_tutorials/groovy-devel/roscpp_tutorials/listener_class/listener_class.cpp

  35 class Listener
  36 {
  37 public:
  38   void callback(const std_msgs::String::ConstPtr& msg);
  39 };

Where the NodeHandle::subscribe() call using a function would have looked like this:

https://raw.github.com/ros/ros_tutorials/groovy-devel/roscpp_tutorials/listener/listener.cpp

  75   ros::Subscriber sub = n.subscribe("chatter", 1000, chatterCallback);

Using a class method looks like this:

https://raw.github.com/ros/ros_tutorials/groovy-devel/roscpp_tutorials/listener_class/listener_class.cpp

  51   Listener listener;
  52   ros::Subscriber sub = n.subscribe("chatter", 1000, &Listener::callback, &listener);

Service Servers

Suppose you have a simple class, AddTwo:

https://raw.github.com/ros/ros_tutorials/groovy-devel/roscpp_tutorials/add_two_ints_server_class/add_two_ints_server_class.cpp

  31 class AddTwo
  32 {
  33 public:
  34   bool add(roscpp_tutorials::TwoInts::Request& req,
  35            roscpp_tutorials::TwoInts::Response& res);
  36 };

Where the old NodeHandle::advertiseService() call would look like:

https://raw.github.com/ros/ros_tutorials/groovy-devel/roscpp_tutorials/add_two_ints_server/add_two_ints_server.cpp

  45   ros::ServiceServer service = n.advertiseService("add_two_ints", add);

The class version looks like this:

https://raw.github.com/ros/ros_tutorials/groovy-devel/roscpp_tutorials/add_two_ints_server_class/add_two_ints_server_class.cpp

  52   AddTwo a;
  53   ros::ServiceServer ss = n.advertiseService("add_two_ints", &AddTwo::add, &a);

For the full set of subscribe(), advertiseService(), etc. overloads, see the NodeHandle class documentation