Wire py_listener to chatter launch (#46)

examples/chatter/BUILD.bazel

@@ -106,15 +106,16 @@ py_binary(
     ],
 )
 
-# Defines a launch target with talker and listener. Just run as
-# `bazel run //examples/chatter:chatter`. This will build the two nodes,
+# Defines a launch target with a talker and two listeners. Just run as
+# `bazel run //examples/chatter:chatter`. This will build the 3 nodes,
 # the deployment and start the launcher.
 ros_launch(
     name = "chatter",
     launch_files = [":chatter.launch"],
     nodes = [
         ":talker",
         ":listener",
+        ":py_listener",
     ],
 )
 

examples/chatter/chatter.launch

@@ -1,4 +1,5 @@
 <launch>
   <node type="chatter/talker" name="talker" />
-  <node type="chatter/listener" name="listener" output="screen" />
+  <node type="chatter/listener" name="cc_listener" output="screen" />
+  <node type="chatter/py_listener" name="py_listener" output="screen" />
 </launch>

examples/chatter/listener.cc

@@ -25,7 +25,7 @@
 #include <ros/ros.h>
 
 void ChatterCallback(const example_msgs::Example& msg) {
-  ROS_INFO_STREAM("Received: " << msg.message);
+  ROS_INFO_STREAM("C++ listener received: " << msg.message);
 }
 
 int main(int argc, char** argv) {

examples/chatter/listener.py

@@ -3,13 +3,12 @@
 
 
 def callback(msg):
-    rospy.loginfo(msg)
+    rospy.loginfo(f'Python listener received: {msg.message}')
 
 
 def main():
     rospy.init_node('listener', anonymous=True)
-    sub = rospy.Subscriber(  # noqa
-        'chatter', example_msgs.msg.Example, callback)
+    rospy.Subscriber('chatter', example_msgs.msg.Example, callback)
     rospy.spin()