polygon_plugin tutorial

edit

Be sure to not miss in your "polygon_plugins" CMakeLists the line

pluginlib_export_plugin_description_file(polygon_base plugins.xml)

The entire CMakeLists must be

    cmake_minimum_required(VERSION 3.5)
project(polygon_plugins)

# 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(ament_cmake_ros REQUIRED)
find_package(polygon_base REQUIRED)
find_package(pluginlib REQUIRED)

add_library(polygon_plugins src/polygon_plugins.cpp)
target_include_directories(polygon_plugins PUBLIC
  $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>
  $<INSTALL_INTERFACE:include>)
ament_target_dependencies(
  polygon_plugins
  "polygon_base"
  "pluginlib"
)

pluginlib_export_plugin_description_file(polygon_base plugins.xml)

# Causes the visibility macros to use dllexport rather than dllimport,
# which is appropriate when building the dll but not consuming it.
target_compile_definitions(polygon_plugins PRIVATE "POLYGON_PLUGINS_BUILDING_LIBRARY")

install(
  DIRECTORY include/
  DESTINATION include
)
install(
  TARGETS polygon_plugins
  EXPORT export_${PROJECT_NAME}
  ARCHIVE DESTINATION lib
  LIBRARY DESTINATION lib
  RUNTIME DESTINATION bin
)

if(BUILD_TESTING)
  find_package(ament_lint_auto REQUIRED)
  # the following line skips the linter which checks for copyrights
  # uncomment the line when a copyright and license is not present in all source files
  #set(ament_cmake_copyright_FOUND TRUE)
  # the following line skips cpplint (only works in a git repo)
  # uncomment the line when this package is not in a git repo
  #set(ament_cmake_cpplint_FOUND TRUE)
  ament_lint_auto_find_test_dependencies()
endif()

ament_export_include_directories(
  include
)
ament_export_libraries(
  polygon_plugins
)
ament_export_targets(
  export_${PROJECT_NAME}
)

ament_package()

Hope it helps