TF Listener
I want to create a class tf_listener. I'm using a laser, so the node for the laser data already exists. I looked at some tutorials and saw that they are using pointstamped. But my laser publishes with the type sensor_msgs/LaserScan. How should I write the subscriber in the class? Or the whole tf listener?
What is your problem precisely? In your case you just create basic subscriber to the topic your laser is publishing to. If you want to do something with the transformation you just get the transformation (look here).
Then you need to convert your laser data to 3d point on which you apply your transformation.