#include <chrono>
#include <memory>

#include "rclcpp/rclcpp.hpp"
#include "tutorial_interfaces/msg/num.hpp" //调用自己定义的msg

using namespace std::chrono_literals;

class MinimalPublisher : public rclcpp::Node
{
public:
  MinimalPublisher()
  : Node("minimal_publisher"), count_(0)
  {
    publisher_ = this->create_publisher<tutorial_interfaces::msg::Num>("topic", 10);    // CHANGE
    timer_ = this->create_wall_timer(
      500ms, std::bind(&MinimalPublisher::timer_callback, this));
  }

private:
  void timer_callback()
  {
    auto message = tutorial_interfaces::msg::Num();
    message.num = this->count_++;
    RCLCPP_INFO(this->get_logger(), "Publishing: '%d'", message.num);
    publisher_->publish(message);
  }
  rclcpp::TimerBase::SharedPtr timer_;
  rclcpp::Publisher<tutorial_interfaces::msg::Num>::SharedPtr publisher_;
  size_t count_;
};

int main(int argc, char * argv[])
{
  rclcpp::init(argc, argv);
  rclcpp::spin(std::make_shared<MinimalPublisher>());
  rclcpp::shutdown();
  return 0;
}

make_minimum_required(VERSION 3.5)
project(cpp_pubsub)

set(CMAKE_SKIP_BUILD_RPATH TRUE)

# Default to C99
if(NOT CMAKE_C_STANDARD)
  set(CMAKE_C_STANDARD 99)
endif()

# Default to C++14
if(NOT CMAKE_CXX_STANDARD)
  set(CMAKE_CXX_STANDARD 14)
endif()

if(CMAKE_COMPILER_IS_GNUCXX OR CMAKE_CXX_COMPILER_ID MATCHES "Clang")
  add_compile_options(-Wall -Wextra -Wpedantic)
endif()

# find dependencies
find_package(ament_cmake REQUIRED)
find_package(rclcpp REQUIRED)
find_package(std_msgs REQUIRED)
find_package(tutorial_interfaces REQUIRED)

include_directories(include)

set(dependencies "rclcpp" "std_msgs" "tutorial_interfaces")

add_executable(talker src/publisher_member_function.cpp)
ament_target_dependencies(talker ${dependencies})

install(TARGETS
  talker
  DESTINATION lib/${PROJECT_NAME})

ament_package()

<?xml version="1.0"?>
<?xml-model href="http://download.ros.org/schema/package_format3.xsd" schematypens="http://www.w3.org/2001/XMLSchema"?>
<package format="3">
  <name>cpp_pubsub</name>
  <version>0.0.0</version>
  <description>TODO: Package description</description>
  <maintainer email="ifan.lyf@alibaba-inc.com">looyifan</maintainer>
  <license>TODO: License declaration</license>

  <buildtool_depend>ament_cmake</buildtool_depend>

  <depend>rclcpp</depend>
  <depend>std_msgs</depend>
  <depend>tutorial_interfaces</depend>

  <test_depend>ament_lint_auto</test_depend>
  <test_depend>ament_lint_common</test_depend>

  <export>
    <build_type>ament_cmake</build_type>
  </export>
</package>