Minor cleanups across the tutorials. (#71)

The main goal of this commit is to synchronize the C++ and
Python code so they look very similar to each other.

Signed-off-by: Chris Lalancette <[email protected]>

Author: clalancette

turtle_tf2_cpp/src/dynamic_frame_tf2_broadcaster.cpp

@@ -30,7 +30,7 @@ class DynamicFrameBroadcaster : public rclcpp::Node
   DynamicFrameBroadcaster()
   : Node("dynamic_frame_tf2_broadcaster")
   {
-    tf_publisher_ = std::make_shared<tf2_ros::TransformBroadcaster>(this);
+    tf_broadcaster_ = std::make_shared<tf2_ros::TransformBroadcaster>(this);
     timer_ = this->create_wall_timer(
       100ms, std::bind(&DynamicFrameBroadcaster::broadcast_timer_callback, this));
   }
@@ -40,8 +40,8 @@ class DynamicFrameBroadcaster : public rclcpp::Node
   {
     rclcpp::Time now = this->get_clock()->now();
     double x = now.seconds() * PI;
-    geometry_msgs::msg::TransformStamped t;
 
+    geometry_msgs::msg::TransformStamped t;
     t.header.stamp = now;
     t.header.frame_id = "turtle1";
     t.child_frame_id = "carrot1";
@@ -53,10 +53,11 @@ class DynamicFrameBroadcaster : public rclcpp::Node
     t.transform.rotation.z = 0.0;
     t.transform.rotation.w = 1.0;
 
-    tf_publisher_->sendTransform(t);
+    tf_broadcaster_->sendTransform(t);
   }
+
   rclcpp::TimerBase::SharedPtr timer_;
-  std::shared_ptr<tf2_ros::TransformBroadcaster> tf_publisher_;
+  std::shared_ptr<tf2_ros::TransformBroadcaster> tf_broadcaster_;
 };
 
 int main(int argc, char * argv[])

turtle_tf2_cpp/src/fixed_frame_tf2_broadcaster.cpp

@@ -28,18 +28,17 @@ class FixedFrameBroadcaster : public rclcpp::Node
   FixedFrameBroadcaster()
   : Node("fixed_frame_tf2_broadcaster")
   {
-    tf_publisher_ = std::make_shared<tf2_ros::TransformBroadcaster>(this);
+    tf_broadcaster_ = std::make_shared<tf2_ros::TransformBroadcaster>(this);
     timer_ = this->create_wall_timer(
       100ms, std::bind(&FixedFrameBroadcaster::broadcast_timer_callback, this));
   }
 
 private:
   void broadcast_timer_callback()
   {
-    rclcpp::Time now = this->get_clock()->now();
     geometry_msgs::msg::TransformStamped t;
 
-    t.header.stamp = now;
+    t.header.stamp = this->get_clock()->now();
     t.header.frame_id = "turtle1";
     t.child_frame_id = "carrot1";
     t.transform.translation.x = 0.0;
@@ -50,10 +49,11 @@ class FixedFrameBroadcaster : public rclcpp::Node
     t.transform.rotation.z = 0.0;
     t.transform.rotation.w = 1.0;
 
-    tf_publisher_->sendTransform(t);
+    tf_broadcaster_->sendTransform(t);
   }
+
   rclcpp::TimerBase::SharedPtr timer_;
-  std::shared_ptr<tf2_ros::TransformBroadcaster> tf_publisher_;
+  std::shared_ptr<tf2_ros::TransformBroadcaster> tf_broadcaster_;
 };
 
 int main(int argc, char * argv[])

turtle_tf2_cpp/src/static_turtle_tf2_broadcaster.cpp

@@ -25,7 +25,7 @@ class StaticFramePublisher : public rclcpp::Node
   explicit StaticFramePublisher(char * transformation[])
   : Node("static_turtle_tf2_broadcaster")
   {
-    tf_publisher_ = std::make_shared<tf2_ros::StaticTransformBroadcaster>(this);
+    tf_static_broadcaster_ = std::make_shared<tf2_ros::StaticTransformBroadcaster>(this);
 
     // Publish static transforms once at startup
     this->make_transforms(transformation);
@@ -34,10 +34,9 @@ class StaticFramePublisher : public rclcpp::Node
 private:
   void make_transforms(char * transformation[])
   {
-    rclcpp::Time now = this->get_clock()->now();
     geometry_msgs::msg::TransformStamped t;
 
-    t.header.stamp = now;
+    t.header.stamp = this->get_clock()->now();
     t.header.frame_id = "world";
     t.child_frame_id = transformation[1];
 
@@ -54,9 +53,10 @@ class StaticFramePublisher : public rclcpp::Node
     t.transform.rotation.z = q.z();
     t.transform.rotation.w = q.w();
 
-    tf_publisher_->sendTransform(t);
+    tf_static_broadcaster_->sendTransform(t);
   }
-  std::shared_ptr<tf2_ros::StaticTransformBroadcaster> tf_publisher_;
+
+  std::shared_ptr<tf2_ros::StaticTransformBroadcaster> tf_static_broadcaster_;
 };
 
 int main(int argc, char * argv[])
@@ -67,7 +67,7 @@ int main(int argc, char * argv[])
   if (argc != 8) {
     RCLCPP_INFO(
       logger, "Invalid number of parameters\nusage: "
-      "ros2 run learning_tf2_cpp static_turtle_tf2_broadcaster "
+      "$ ros2 run learning_tf2_cpp static_turtle_tf2_broadcaster "
       "child_frame_name x y z roll pitch yaw");
     return 1;
   }
@@ -76,7 +76,7 @@ int main(int argc, char * argv[])
   // necessary to check that the frame name passed is different
   if (strcmp(argv[1], "world") == 0) {
     RCLCPP_INFO(logger, "Your static turtle name cannot be 'world'");
-    return 1;
+    return 2;
   }
 
   // Pass parameters and initialize node

turtle_tf2_cpp/src/turtle_tf2_broadcaster.cpp

@@ -30,8 +30,7 @@ class FramePublisher : public rclcpp::Node
   : Node("turtle_tf2_frame_publisher")
   {
     // Declare and acquire `turtlename` parameter
-    this->declare_parameter<std::string>("turtlename", "turtle");
-    this->get_parameter("turtlename", turtlename_);
+    turtlename_ = this->declare_parameter<std::string>("turtlename", "turtle");
 
     // Initialize the transform broadcaster
     tf_broadcaster_ =
@@ -51,12 +50,11 @@ class FramePublisher : public rclcpp::Node
 private:
   void handle_turtle_pose(const std::shared_ptr<turtlesim::msg::Pose> msg)
   {
-    rclcpp::Time now = this->get_clock()->now();
     geometry_msgs::msg::TransformStamped t;
 
     // Read message content and assign it to
     // corresponding tf variables
-    t.header.stamp = now;
+    t.header.stamp = this->get_clock()->now();
     t.header.frame_id = "world";
     t.child_frame_id = turtlename_.c_str();
 
@@ -79,6 +77,7 @@ class FramePublisher : public rclcpp::Node
     // Send the transformation
     tf_broadcaster_->sendTransform(t);
   }
+
   rclcpp::Subscription<turtlesim::msg::Pose>::SharedPtr subscription_;
   std::unique_ptr<tf2_ros::TransformBroadcaster> tf_broadcaster_;
   std::string turtlename_;

turtle_tf2_cpp/src/turtle_tf2_listener.cpp

@@ -36,12 +36,11 @@ class FrameListener : public rclcpp::Node
     turtle_spawned_(false)
   {
     // Declare and acquire `target_frame` parameter
-    this->declare_parameter<std::string>("target_frame", "turtle1");
-    this->get_parameter("target_frame", target_frame_);
+    target_frame_ = this->declare_parameter<std::string>("target_frame", "turtle1");
 
     tf_buffer_ =
       std::make_unique<tf2_ros::Buffer>(this->get_clock());
-    transform_listener_ =
+    tf_listener_ =
       std::make_shared<tf2_ros::TransformListener>(*tf_buffer_);
 
     // Create a client to spawn a turtle
@@ -67,15 +66,15 @@ class FrameListener : public rclcpp::Node
 
     if (turtle_spawning_service_ready_) {
       if (turtle_spawned_) {
-        geometry_msgs::msg::TransformStamped transformStamped;
+        geometry_msgs::msg::TransformStamped t;
 
         // Look up for the transformation between target_frame and turtle2 frames
         // and send velocity commands for turtle2 to reach target_frame
         try {
-          transformStamped = tf_buffer_->lookupTransform(
+          t = tf_buffer_->lookupTransform(
             toFrameRel, fromFrameRel,
             tf2::TimePointZero);
-        } catch (tf2::TransformException & ex) {
+        } catch (const tf2::TransformException & ex) {
           RCLCPP_INFO(
             this->get_logger(), "Could not transform %s to %s: %s",
             toFrameRel.c_str(), fromFrameRel.c_str(), ex.what());
@@ -86,13 +85,13 @@ class FrameListener : public rclcpp::Node
 
         static const double scaleRotationRate = 1.0;
         msg.angular.z = scaleRotationRate * atan2(
-          transformStamped.transform.translation.y,
-          transformStamped.transform.translation.x);
+          t.transform.translation.y,
+          t.transform.translation.x);
 
         static const double scaleForwardSpeed = 0.5;
         msg.linear.x = scaleForwardSpeed * sqrt(
-          pow(transformStamped.transform.translation.x, 2) +
-          pow(transformStamped.transform.translation.y, 2));
+          pow(t.transform.translation.x, 2) +
+          pow(t.transform.translation.y, 2));
 
         publisher_->publish(msg);
       } else {
@@ -105,10 +104,10 @@ class FrameListener : public rclcpp::Node
         // Initialize request with turtle name and coordinates
         // Note that x, y and theta are defined as floats in turtlesim/srv/Spawn
         auto request = std::make_shared<turtlesim::srv::Spawn::Request>();
+        request->name = "turtle2";
         request->x = 4.0;
         request->y = 2.0;
         request->theta = 0.0;
-        request->name = "turtle2";
 
         // Call request
         using ServiceResponseFuture =
@@ -127,6 +126,7 @@ class FrameListener : public rclcpp::Node
       }
     }
   }
+
   // Boolean values to store the information
   // if the service for spawning turtle is available
   bool turtle_spawning_service_ready_;
@@ -135,7 +135,7 @@ class FrameListener : public rclcpp::Node
   rclcpp::Client<turtlesim::srv::Spawn>::SharedPtr spawner_{nullptr};
   rclcpp::TimerBase::SharedPtr timer_{nullptr};
   rclcpp::Publisher<geometry_msgs::msg::Twist>::SharedPtr publisher_{nullptr};
-  std::shared_ptr<tf2_ros::TransformListener> transform_listener_{nullptr};
+  std::shared_ptr<tf2_ros::TransformListener> tf_listener_{nullptr};
   std::unique_ptr<tf2_ros::Buffer> tf_buffer_;
   std::string target_frame_;
 };

turtle_tf2_cpp/src/turtle_tf2_message_filter.cpp

@@ -38,8 +38,7 @@ class PoseDrawer : public rclcpp::Node
   : Node("turtle_tf2_pose_drawer")
   {
     // Declare and acquire `target_frame` parameter
-    this->declare_parameter<std::string>("target_frame", "turtle1");
-    this->get_parameter("target_frame", target_frame_);
+    target_frame_ = this->declare_parameter<std::string>("target_frame", "turtle1");
 
     typedef std::chrono::duration<int> seconds_type;
     seconds_type buffer_timeout(1);
@@ -73,7 +72,7 @@ class PoseDrawer : public rclcpp::Node
         point_out.point.x,
         point_out.point.y,
         point_out.point.z);
-    } catch (tf2::TransformException & ex) {
+    } catch (const tf2::TransformException & ex) {
       RCLCPP_WARN(
         // Print exception which was caught
         this->get_logger(), "Failure %s\n", ex.what());

turtle_tf2_py/turtle_tf2_py/dynamic_frame_tf2_broadcaster.py

@@ -26,7 +26,7 @@ class DynamicFrameBroadcaster(Node):
 
     def __init__(self):
         super().__init__('dynamic_frame_tf2_broadcaster')
-        self.br = TransformBroadcaster(self)
+        self.tf_broadcaster = TransformBroadcaster(self)
         self.timer = self.create_timer(0.1, self.broadcast_timer_callback)
 
     def broadcast_timer_callback(self):
@@ -45,7 +45,7 @@ def broadcast_timer_callback(self):
         t.transform.rotation.z = 0.0
         t.transform.rotation.w = 1.0
 
-        self.br.sendTransform(t)
+        self.tf_broadcaster.sendTransform(t)
 
 
 def main():

turtle_tf2_py/turtle_tf2_py/fixed_frame_tf2_broadcaster.py

@@ -24,11 +24,12 @@ class FixedFrameBroadcaster(Node):
 
     def __init__(self):
         super().__init__('fixed_frame_tf2_broadcaster')
-        self.br = TransformBroadcaster(self)
+        self.tf_broadcaster = TransformBroadcaster(self)
         self.timer = self.create_timer(0.1, self.broadcast_timer_callback)
 
     def broadcast_timer_callback(self):
         t = TransformStamped()
+
         t.header.stamp = self.get_clock().now().to_msg()
         t.header.frame_id = 'turtle1'
         t.child_frame_id = 'carrot1'
@@ -40,7 +41,7 @@ def broadcast_timer_callback(self):
         t.transform.rotation.z = 0.0
         t.transform.rotation.w = 1.0
 
-        self.br.sendTransform(t)
+        self.tf_broadcaster.sendTransform(t)
 
 
 def main():

turtle_tf2_py/turtle_tf2_py/static_turtle_tf2_broadcaster.py

@@ -65,42 +65,44 @@ class StaticFramePublisher(Node):
     def __init__(self, transformation):
         super().__init__('static_turtle_tf2_broadcaster')
 
-        self._tf_publisher = StaticTransformBroadcaster(self)
+        self.tf_static_broadcaster = StaticTransformBroadcaster(self)
 
         # Publish static transforms once at startup
         self.make_transforms(transformation)
 
     def make_transforms(self, transformation):
-        static_transformStamped = TransformStamped()
-        static_transformStamped.header.stamp = self.get_clock().now().to_msg()
-        static_transformStamped.header.frame_id = 'world'
-        static_transformStamped.child_frame_id = sys.argv[1]
-        static_transformStamped.transform.translation.x = float(sys.argv[2])
-        static_transformStamped.transform.translation.y = float(sys.argv[3])
-        static_transformStamped.transform.translation.z = float(sys.argv[4])
+        t = TransformStamped()
+
+        t.header.stamp = self.get_clock().now().to_msg()
+        t.header.frame_id = 'world'
+        t.child_frame_id = transformation[1]
+
+        t.transform.translation.x = float(transformation[2])
+        t.transform.translation.y = float(transformation[3])
+        t.transform.translation.z = float(transformation[4])
         quat = quaternion_from_euler(
-            float(sys.argv[5]), float(sys.argv[6]), float(sys.argv[7]))
-        static_transformStamped.transform.rotation.x = quat[0]
-        static_transformStamped.transform.rotation.y = quat[1]
-        static_transformStamped.transform.rotation.z = quat[2]
-        static_transformStamped.transform.rotation.w = quat[3]
+            float(transformation[5]), float(transformation[6]), float(transformation[7]))
+        t.transform.rotation.x = quat[0]
+        t.transform.rotation.y = quat[1]
+        t.transform.rotation.z = quat[2]
+        t.transform.rotation.w = quat[3]
 
-        self._tf_publisher.sendTransform(static_transformStamped)
+        self.tf_static_broadcaster.sendTransform(t)
 
 
 def main():
     logger = rclpy.logging.get_logger('logger')
 
     # obtain parameters from command line arguments
-    if len(sys.argv) < 8:
+    if len(sys.argv) != 8:
         logger.info('Invalid number of parameters. Usage: \n'
                     '$ ros2 run turtle_tf2_py static_turtle_tf2_broadcaster'
                     'child_frame_name x y z roll pitch yaw')
-        sys.exit(0)
-    else:
-        if sys.argv[1] == 'world':
-            logger.info('Your static turtle name cannot be "world"')
-            sys.exit(0)
+        sys.exit(1)
+
+    if sys.argv[1] == 'world':
+        logger.info('Your static turtle name cannot be "world"')
+        sys.exit(2)
 
     # pass parameters and initialize node
     rclpy.init()

turtle_tf2_py/turtle_tf2_py/turtle_tf2_broadcaster.py

@@ -60,12 +60,11 @@ def __init__(self):
         super().__init__('turtle_tf2_frame_publisher')
 
         # Declare and acquire `turtlename` parameter
-        self.declare_parameter('turtlename', 'turtle')
-        self.turtlename = self.get_parameter(
-            'turtlename').get_parameter_value().string_value
+        self.turtlename = self.declare_parameter(
+            'turtlename', 'turtle').get_parameter_value().string_value
 
         # Initialize the transform broadcaster
-        self.br = TransformBroadcaster(self)
+        self.tf_broadcaster = TransformBroadcaster(self)
 
         # Subscribe to a turtle{1}{2}/pose topic and call handle_turtle_pose
         # callback function on each message
@@ -74,7 +73,7 @@ def __init__(self):
             f'/{self.turtlename}/pose',
             self.handle_turtle_pose,
             1)
-        self.subscription
+        self.subscription  # prevent unused variable warning
 
     def handle_turtle_pose(self, msg):
         t = TransformStamped()
@@ -101,7 +100,7 @@ def handle_turtle_pose(self, msg):
         t.transform.rotation.w = q[3]
 
         # Send the transformation
-        self.br.sendTransform(t)
+        self.tf_broadcaster.sendTransform(t)
 
 
 def main():