From 3b720a2682015eeb769643f89641a54c5169a572 Mon Sep 17 00:00:00 2001
From: Johannes Mey <johannes.mey@tu-dresden.de>
Date: Tue, 1 Sep 2020 12:47:56 +0200
Subject: [PATCH] add some comments
---
src/listener.cpp | 10 ++++++++--
src/talker.cpp | 12 ++++++++++++
2 files changed, 20 insertions(+), 2 deletions(-)
diff --git a/src/listener.cpp b/src/listener.cpp
index 0c60b11..6ac2396 100644
--- a/src/listener.cpp
+++ b/src/listener.cpp
@@ -4,6 +4,11 @@
/**
* This tutorial demonstrates simple receipt of messages over the ROS system.
*/
+
+/**
+ * This callback function is called when a message on the topic "chatter" is received
+ * @param msg The received message
+ */
void chatterCallback(const std_msgs::String::ConstPtr& msg)
{
ROS_INFO("I heard: [%s]", msg->data.c_str());
@@ -26,7 +31,8 @@ int main(int argc, char **argv)
/**
* NodeHandle is the main access point to communications with the ROS system.
* The first NodeHandle constructed will fully initialize this node, and the last
- * NodeHandle destructed will close down the node.
+ * NodeHandle destructed will close down the node. The NodeHandle can be initialized
+ * with a namespace, which is relevant for the parameter server.
*/
ros::NodeHandle n;
@@ -50,7 +56,7 @@ int main(int argc, char **argv)
/**
* ros::spin() will enter a loop, pumping callbacks. With this version, all
* callbacks will be called from within this thread (the main one). ros::spin()
- * will exit when Ctrl-C is pressed, or the node is shutdown by the master.
+ * will exit when Ctrl-C is pressed, or the node is shut down by the master.
*/
ros::spin();
diff --git a/src/talker.cpp b/src/talker.cpp
index 9cf75a9..a6fd3be 100644
--- a/src/talker.cpp
+++ b/src/talker.cpp
@@ -53,6 +53,10 @@ int main(int argc, char **argv)
* a unique string for each message.
*/
int count = 0;
+
+ /**
+ * The main loop runs until the ros core is shutting down.
+ */
while (ros::ok())
{
/**
@@ -74,9 +78,17 @@ int main(int argc, char **argv)
*/
chatter_pub.publish(msg);
+ /**
+ * The spinOnce() method processes callbacks.
+ */
ros::spinOnce();
+ /**
+ * To prevent too many messages being sent and busy waiting, we sleep for some time here (the rate is 10hz,
+ * so we sleep for 100ms).
+ */
loop_rate.sleep();
+
++count;
}
--
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