ros2_tracing/tracetools_test/src/test_subscription.cpp

#include <memory>

#include "rclcpp/rclcpp.hpp"
#include "std_msgs/msg/string.hpp"

class SubNode : public rclcpp::Node
{
public:
  explicit SubNode(rclcpp::NodeOptions options)
  : Node("sub_node", options)
  {
    sub_ = this->create_subscription<std_msgs::msg::String>(
      "the_topic",
      rclcpp::QoS(10),
      std::bind(&SubNode::callback, this, std::placeholders::_1));
  }

private:
  void callback(const std_msgs::msg::String::SharedPtr msg)
  {
    // Nothing
    (void)msg;
  }

  rclcpp::Subscription<std_msgs::msg::String>::SharedPtr sub_;
};

int main(int argc, char * argv[])
{
  rclcpp::init(argc, argv);

  rclcpp::executors::SingleThreadedExecutor exec;
  auto sub_node = std::make_shared<SubNode>(rclcpp::NodeOptions());
  exec.add_node(sub_node);

  printf("spinning once\n");
  exec.spin_once();

  rclcpp::shutdown();
  return 0;
}