export symbols in laser_proc component

CMakeLists.txt

@@ -28,6 +28,10 @@ ament_target_dependencies(laser_proc
   rclcpp
   sensor_msgs
 )
+# Causes the visibility macros to use dllexport rather than dllimport,
+# which is appropriate when building the dll but not consuming it.
+target_compile_definitions(${PROJECT_NAME}
+  PRIVATE "LASER_PROC_BUILDING_LIBRARY")
 
 ## Laser Proc component
 add_library(laser_proc_component SHARED src/laser_proc_component.cpp)

include/laser_proc/laser_proc.hpp

@@ -38,17 +38,22 @@
 #include "sensor_msgs/msg/laser_scan.hpp"
 #include "sensor_msgs/msg/multi_echo_laser_scan.hpp"
 
+#include "visibility_control.hpp"
+
 namespace laser_proc
 {
 class LaserProc
 {
 public:
+  LASER_PROC_PUBLIC
   static sensor_msgs::msg::LaserScan getFirstScan(
     const sensor_msgs::msg::MultiEchoLaserScan & msg);
 
+  LASER_PROC_PUBLIC
   static sensor_msgs::msg::LaserScan getLastScan(
     const sensor_msgs::msg::MultiEchoLaserScan & msg);
 
+  LASER_PROC_PUBLIC
   static sensor_msgs::msg::LaserScan getMostIntenseScan(
     const sensor_msgs::msg::MultiEchoLaserScan & msg);
 

include/laser_proc/laser_publisher.hpp

@@ -42,15 +42,19 @@
 
 #include "sensor_msgs/msg/multi_echo_laser_scan.hpp"
 
+#include "visibility_control.hpp"
+
 namespace laser_proc
 {
 
 class LaserPublisher
 {
 public:
+  LASER_PROC_PUBLIC
   explicit LaserPublisher(
     rclcpp::Node::SharedPtr & nh, uint32_t queue_size, bool publish_echoes = true);
 
+  LASER_PROC_PUBLIC
   explicit LaserPublisher(
     std::shared_ptr<rclcpp::node_interfaces::NodeTopicsInterface> topics_interface,
     uint32_t queue_size,
@@ -62,31 +66,40 @@ class LaserPublisher
    *
    * Returns sum of all child publishers.
    */
-  uint32_t getNumSubscribers() const;
+  LASER_PROC_PUBLIC
+  size_t getNumSubscribers() const;
 
   /*!
    * \brief Returns the topics of this LaserPublisher.
    */
+  LASER_PROC_PUBLIC
   std::vector<std::string> getTopics() const;
 
   /*!
    * \brief Publish a MultiEchoLaserScan on the topics associated with this LaserPublisher.
    */
+  LASER_PROC_PUBLIC
   void publish(const sensor_msgs::msg::MultiEchoLaserScan & msg) const;
 
   /*!
    * \brief Publish a MultiEchoLaserScan on the topics associated with this LaserPublisher.
    */
+  LASER_PROC_PUBLIC
   void publish(sensor_msgs::msg::MultiEchoLaserScan::ConstSharedPtr msg) const;
 
   /*!
    * \brief Shutdown the advertisements associated with this Publisher.
    */
+  LASER_PROC_PUBLIC
   void shutdown();
 
+  LASER_PROC_PUBLIC
   operator void *() const;
+  LASER_PROC_PUBLIC
   bool operator<(const LaserPublisher & rhs) const {return impl_ < rhs.impl_;}
+  LASER_PROC_PUBLIC
   bool operator!=(const LaserPublisher & rhs) const {return impl_ != rhs.impl_;}
+  LASER_PROC_PUBLIC
   bool operator==(const LaserPublisher & rhs) const {return impl_ == rhs.impl_;}
 
 private:

include/laser_proc/visibility_control.hpp

@@ -0,0 +1,56 @@
+// Copyright 2015 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.
+
+/* This header must be included by all rclcpp headers which declare symbols
+ * which are defined in the rclcpp library. When not building the rclcpp
+ * library, i.e. when using the headers in other package's code, the contents
+ * of this header change the visibility of certain symbols which the rclcpp
+ * library cannot have, but the consuming code must have inorder to link.
+ */
+
+#ifndef LASER_PROC__VISIBILITY_CONTROL_HPP_
+#define LASER_PROC__VISIBILITY_CONTROL_HPP_
+
+// This logic was borrowed (then namespaced) from the examples on the gcc wiki:
+//     https://gcc.gnu.org/wiki/Visibility
+
+#if defined _WIN32 || defined __CYGWIN__
+  #ifdef __GNUC__
+    #define LASER_PROC_EXPORT __attribute__ ((dllexport))
+    #define LASER_PROC_IMPORT __attribute__ ((dllimport))
+  #else
+    #define LASER_PROC_EXPORT __declspec(dllexport)
+    #define LASER_PROC_IMPORT __declspec(dllimport)
+  #endif
+  #ifdef LASER_PROC_BUILDING_LIBRARY
+    #define LASER_PROC_PUBLIC LASER_PROC_EXPORT
+  #else
+    #define LASER_PROC_PUBLIC LASER_PROC_IMPORT
+  #endif
+  #define LASER_PROC_PUBLIC_TYPE LASER_PROC_PUBLIC
+  #define LASER_PROC_LOCAL
+#else
+  #define LASER_PROC_EXPORT __attribute__ ((visibility("default")))
+  #define LASER_PROC_IMPORT
+  #if __GNUC__ >= 4
+    #define LASER_PROC_PUBLIC __attribute__ ((visibility("default")))
+    #define LASER_PROC_LOCAL  __attribute__ ((visibility("hidden")))
+  #else
+    #define LASER_PROC_PUBLIC
+    #define LASER_PROC_LOCAL
+  #endif
+  #define LASER_PROC_PUBLIC_TYPE
+#endif
+
+#endif  // LASER_PROC__VISIBILITY_CONTROL_HPP_

src/laser_publisher.cpp

@@ -107,9 +107,9 @@ LaserPublisher::LaserPublisher(
   impl_->functs_.push_back(laser_proc::LaserProc::getMostIntenseScan);
 }
 
-uint32_t LaserPublisher::getNumSubscribers() const
+size_t LaserPublisher::getNumSubscribers() const
 {
-  uint32_t num = 0;
+  size_t num = 0;
 
   if (impl_ && impl_->isValid()) {
     num += impl_->echo_pub_->get_subscription_count();