add demo_3_class

demo_cpp/3_publisher_class.cpp

@@ -0,0 +1,36 @@
+#include "rclcpp/rclcpp.hpp"
+#include "std_msgs/msg/string.hpp"
+
+class PublisherNode : public rclcpp::Node
+{
+public:
+  PublisherNode()
+    : Node("publisher_node")
+  {
+    publisher_ = create_publisher<std_msgs::msg::String>("/my_topic", 10);
+    timer_ = create_wall_timer(
+      std::chrono::milliseconds(1000), 
+      std::bind(&PublisherNode::publishMessage, this)
+      );
+  }
+
+private:
+  void publishMessage()
+  {
+    message_.data = "Hello World!";
+    publisher_->publish(message_);
+  }
+
+  rclcpp::Publisher<std_msgs::msg::String>::SharedPtr publisher_;
+  std_msgs::msg::String message_;
+  rclcpp::TimerBase::SharedPtr timer_;
+};
+
+int main(int argc, char * argv[])
+{
+  rclcpp::init(argc, argv);
+  auto node = std::make_shared<PublisherNode>();
+  rclcpp::spin(node);
+  rclcpp::shutdown();
+  return 0;
+}

demo_cpp/3_subscriber_class.cpp

@@ -0,0 +1,32 @@
+#include "rclcpp/rclcpp.hpp"
+#include "std_msgs/msg/string.hpp"
+
+class SubscriberNode : public rclcpp::Node
+{
+public:
+  SubscriberNode()
+    : Node("subscriber_node")
+  {
+    subscriber_ = create_subscription<std_msgs::msg::String>(
+      "/my_topic", 
+      10, 
+      std::bind(&SubscriberNode::callback, this, std::placeholders::_1));
+  }
+
+private:
+  void callback(const std_msgs::msg::String::SharedPtr msg)
+  {
+    RCLCPP_INFO(get_logger(), "Receive : %s", msg->data.c_str());
+  }
+
+  rclcpp::Subscription<std_msgs::msg::String>::SharedPtr subscriber_;
+};
+
+int main(int argc, char * argv[])
+{
+  rclcpp::init(argc, argv);
+  auto node = std::make_shared<SubscriberNode>();
+  rclcpp::spin(node);
+  rclcpp::shutdown();
+  return 0;
+}