Add a service lambda example

Author: threeal

rclcpp/services/minimal_client/member_function.cpp

@@ -30,7 +30,7 @@ class MinimalClient : public rclcpp::Node
 {
 public:
   MinimalClient()
-  : Node("minimal_service")
+  : Node("minimal_client")
   {
     client_ = this->create_client<AddTwoInts>("add_two_ints");
     while (!client_->wait_for_service(1s)) {

rclcpp/services/minimal_service/CMakeLists.txt

@@ -14,13 +14,17 @@ find_package(ament_cmake REQUIRED)
 find_package(example_interfaces REQUIRED)
 find_package(rclcpp REQUIRED)
 
-add_executable(service_not_composable not_composable.cpp)
-ament_target_dependencies(service_not_composable rclcpp example_interfaces)
+add_executable(service_lambda lambda.cpp)
+ament_target_dependencies(service_lambda rclcpp example_interfaces)
 
 add_executable(service_member_function member_function.cpp)
 ament_target_dependencies(service_member_function rclcpp example_interfaces)
 
+add_executable(service_not_composable not_composable.cpp)
+ament_target_dependencies(service_not_composable rclcpp example_interfaces)
+
 install(TARGETS
+  service_lambda
   service_not_composable
   service_member_function
   DESTINATION lib/${PROJECT_NAME})

rclcpp/services/minimal_service/lambda.cpp

@@ -0,0 +1,55 @@
+// Copyright 2016 Open Source Robotics Foundation, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <cinttypes>
+#include <functional>
+#include <memory>
+
+#include "example_interfaces/srv/add_two_ints.hpp"
+#include "rclcpp/rclcpp.hpp"
+
+using example_interfaces::srv::AddTwoInts;
+
+/* This example creates a subclass of Node and uses a fancy C++11 lambda
+ * function to shorten the callback syntax, at the expense of making the
+ * code somewhat more difficult to understand at first glance. */
+
+class MinimalService : public rclcpp::Node
+{
+public:
+  MinimalService()
+  : Node("minimal_service")
+  {
+    server_ = this->create_service<AddTwoInts>(
+      "add_two_ints",
+      [this](const AddTwoInts::Request::SharedPtr request,
+      AddTwoInts::Response::SharedPtr response) {
+        RCLCPP_INFO(
+          this->get_logger(),
+          "request: %" PRId64 " + %" PRId64, request->a, request->b);
+        response->sum = request->a + request->b;
+      });
+  }
+
+private:
+  rclcpp::Service<AddTwoInts>::SharedPtr server_;
+};
+
+int main(int argc, char * argv[])
+{
+  rclcpp::init(argc, argv);
+  rclcpp::spin(std::make_shared<MinimalService>());
+  rclcpp::shutdown();
+  return 0;
+}

rclcpp/topics/minimal_publisher/lambda.cpp

@@ -33,7 +33,7 @@ class MinimalPublisher : public rclcpp::Node
   {
     publisher_ = this->create_publisher<std_msgs::msg::String>("topic", 10);
     auto timer_callback =
-      [this]() -> void {
+      [this]() {
         auto message = std_msgs::msg::String();
         message.data = "Hello, world! " + std::to_string(this->count_++);
         RCLCPP_INFO(this->get_logger(), "Publishing: '%s'", message.data.c_str());

rclcpp/topics/minimal_subscriber/lambda.cpp

@@ -17,6 +17,10 @@
 #include "rclcpp/rclcpp.hpp"
 #include "std_msgs/msg/string.hpp"
 
+/* This example creates a subclass of Node and uses a fancy C++11 lambda
+ * function to shorten the callback syntax, at the expense of making the
+ * code somewhat more difficult to understand at first glance. */
+
 class MinimalSubscriber : public rclcpp::Node
 {
 public:
@@ -26,7 +30,7 @@ class MinimalSubscriber : public rclcpp::Node
     subscription_ = this->create_subscription<std_msgs::msg::String>(
       "topic",
       10,
-      [this](std_msgs::msg::String::UniquePtr msg) {
+      [this](const std_msgs::msg::String::SharedPtr msg) {
         RCLCPP_INFO(this->get_logger(), "I heard: '%s'", msg->data.c_str());
       });
   }