sub = new ros::Subscriber(rosNodeHandle->subscribe(url.getPath(), 1000, &RosAphModule::subscriptionCallback, this));
but this cannot be done, since the callback should be something like:
void RosAphModule::subscriptionCallback(const ros::Message::ConstPtr& msg)
that is not allowed, because ros::Message is an abstract type and the compiler says what I paste at the end of this email... moreover, I would like to know how to get the topic the message was coming from (given the ros::Message& msg in the callback, I mean).