first try of node like something

Signed-off-by: Karsten Knese <karsten@openrobotics.org>

rclcpp/CMakeLists.txt

@@ -85,19 +85,40 @@ configure_file(
   COPYONLY
 )
 # generate header with logging macros
-set(python_code
+set(python_code_logging
   "import em"
   "em.invoke(['-o', 'include/rclcpp/logging.hpp', '${CMAKE_CURRENT_SOURCE_DIR}/resource/logging.hpp.em'])")
-string(REPLACE ";" "$<SEMICOLON>" python_code "${python_code}")
+string(REPLACE ";" "$<SEMICOLON>" python_code_logging "${python_code_logging}")
 add_custom_command(OUTPUT include/rclcpp/logging.hpp
   COMMAND ${CMAKE_COMMAND} -E make_directory "include/rclcpp"
-  COMMAND ${PYTHON_EXECUTABLE} ARGS -c "${python_code}"
+  COMMAND ${PYTHON_EXECUTABLE} ARGS -c "${python_code_logging}"
   DEPENDS "${CMAKE_CURRENT_BINARY_DIR}/logging.hpp.em.watch"
   COMMENT "Expanding logging.hpp.em"
   VERBATIM
 )
 list(APPEND ${PROJECT_NAME}_SRCS
   include/rclcpp/logging.hpp)
+
+# "watch" template for changes
+configure_file(
+  "resource/interface_traits.hpp.em"
+  "interface_traits.hpp.em.watch"
+  COPYONLY
+)
+set(python_code_interface_traits
+  "import em"
+  "em.invoke(['-o', 'include/rclcpp/node_interfaces/interface_traits.hpp', '${CMAKE_CURRENT_SOURCE_DIR}/resource/interface_traits.hpp.em'])")
+string(REPLACE ";" "$<SEMICOLON>" python_code_interface_traits "${python_code_interface_traits}")
+add_custom_command(OUTPUT include/rclcpp/node_interfaces/interface_traits.hpp
+  COMMAND ${CMAKE_COMMAND} -E make_directory "include/rclcpp/node_interfaces"
+  COMMAND ${PYTHON_EXECUTABLE} ARGS -c "${python_code_interface_traits}"
+  DEPENDS "${CMAKE_CURRENT_BINARY_DIR}/interface_traits.hpp.em.watch"
+  COMMENT "Expanding interfae_traits.hpp.em"
+  VERBATIM
+)
+list(APPEND ${PROJECT_NAME}_SRCS
+  include/rclcpp/node_interfaces/interface_traits.hpp)
+
 include_directories("${CMAKE_CURRENT_BINARY_DIR}/include")
 
 add_library(${PROJECT_NAME}
@@ -448,6 +469,14 @@ if(BUILD_TESTING)
     target_link_libraries(test_init ${PROJECT_NAME})
   endif()
 
+  ament_add_gtest(test_interface_traits test/test_interface_traits.cpp
+    APPEND_LIBRARY_DIRS "${append_library_dirs}")
+  if(TARGET test_interface_traits)
+    ament_target_dependencies(test_interface_traits
+      "rcl")
+    target_link_libraries(test_interface_traits ${PROJECT_NAME})
+  endif()
+
   ament_add_gtest(test_multi_threaded_executor test/executors/test_multi_threaded_executor.cpp
     APPEND_LIBRARY_DIRS "${append_library_dirs}")
   if(TARGET test_multi_threaded_executor)

rclcpp/resource/interface_traits.hpp.em

@@ -0,0 +1,77 @@
+// Copyright 2019 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.
+
+#ifndef RCLCPP__NODE_INTERFACES__INTERFACE_TRAITS_HPP_
+#define RCLCPP__NODE_INTERFACES__INTERFACE_TRAITS_HPP_
+
+#include <functional>
+#include <type_traits>
+
+@{
+node_interfaces = [
+  'node_base_interface',
+  'node_clock_interface',
+  'node_graph_interface',
+  'node_logging_interface',
+  'node_parameters_interface',
+  'node_services_interface',
+  'node_time_source_interface',
+  'node_timers_interface',
+  'node_topics_interface',
+  'node_waitables_interface',
+]
+
+node_interface_types = [
+  'NodeBaseInterface',
+  'NodeClockInterface',
+  'NodeGraphInterface',
+  'NodeLoggingInterface',
+  'NodeParametersInterface',
+  'NodeServicesInterface',
+  'NodeTimeSourceInterface',
+  'NodeTimersInterface',
+  'NodeTopicsInterface',
+  'NodeWaitablesInterface',
+]
+
+assert (len(node_interfaces) == len(node_interface_types))
+}@
+
+@[for interface_ in node_interfaces]@
+#include "rclcpp/node_interfaces/@(interface_).hpp"
+@[end for]@
+
+namespace rclcpp
+{
+namespace node_interfaces
+{
+
+@[for (interface_, type_) in zip(node_interfaces, node_interface_types)]@
+using @(interface_)_getter_t = std::shared_ptr<rclcpp::node_interfaces::@(type_)>;
+
+template<class T, typename = void>
+struct has_@(interface_) : std::false_type
+{};
+
+template<class T>
+struct has_@(interface_)<
+  T, typename std::enable_if<
+    std::is_same<
+      @(interface_)_getter_t, decltype(std::declval<T>().get_@(interface_)())>::value>::type> : std::true_type
+{};
+
+@[end for]@
+}  // namespace node_interfaces
+}  // namespace rclcpp
+#endif  // RCLCPP__NODE_INTERFACES__INTERFACE_TRAITS_HPP_

rclcpp/test/test_interface_traits.cpp

@@ -0,0 +1,51 @@
+// Copyright 2019 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 <gtest/gtest.h>
+
+#include "rclcpp/node_interfaces/interface_traits.hpp"
+#include "rclcpp/node_interfaces/node_base.hpp"
+#include "rclcpp/node.hpp"
+
+class MyNode
+{
+public:
+  std::shared_ptr<rclcpp::node_interfaces::NodeBaseInterface> get_node_base_interface() const
+  {
+    return std::make_shared<rclcpp::node_interfaces::NodeBase>("my_node_name", "my_node_namespace", nullptr, rclcpp::NodeOptions());
+  }
+};
+
+class WrongNode
+{
+public:
+  std::shared_ptr<rclcpp::node_interfaces::NodeBaseInterface> not_get_node_base_interface()
+  {
+    return nullptr;
+  }
+};
+
+template<class T, typename std::enable_if<rclcpp::node_interfaces::has_node_base_interface<T>::value>::type* = nullptr>
+void get_node_name(const T & nodelike) {
+  ASSERT_STREQ("my_node_name", nodelike.get_node_base_interface()->get_name());
+}
+
+TEST(TestInterfaceTraits, has_node_base_interface) {
+  ASSERT_TRUE(rclcpp::node_interfaces::has_node_base_interface<MyNode>::value);
+  ASSERT_FALSE(rclcpp::node_interfaces::has_node_base_interface<WrongNode>::value);
+  ASSERT_TRUE(rclcpp::node_interfaces::has_node_base_interface<rclcpp::Node>::value);
+
+  get_node_name(MyNode());
+}
+