To keep track of TODOs mentioned with #320:

• try minimizing the amount of includes [JTC] Cleanup includes #943
• check if this is needed at all [JTC] Cleanup includes #943
  

  ros2_controllers/joint_trajectory_controller/include/joint_trajectory_controller/joint_trajectory_controller.hpp

  Lines 53 to 61 in 4c6d723

  	namespace rclcpp_action
  	{
  	template <typename ActionT>
  	class ServerGoalHandle;
  	} // namespace rclcpp_action
  	namespace rclcpp_lifecycle
  	{
  	class State;
  	} // namespace rclcpp_lifecycle

• clean the mess of trajectory msg pointers
• rename read_state_from_hardware
• try refactoring these into trajectory_operations.cpp or into trajectory.hpp directly

  ros2_controllers/joint_trajectory_controller/include/joint_trajectory_controller/joint_trajectory_controller.hpp

  Lines 224 to 241 in 4c6d723

  	// fill trajectory_msg so it matches joints controlled by this controller
  	// positions set to current position, velocities, accelerations and efforts to 0.0
  	JOINT_TRAJECTORY_CONTROLLER_PUBLIC
  	void fill_partial_goal(
  	std::shared_ptr<trajectory_msgs::msg::JointTrajectory> trajectory_msg) const;
  	// sorts the joints of the incoming message to our local order
  	JOINT_TRAJECTORY_CONTROLLER_PUBLIC
  	void sort_to_local_joint_order(
  	std::shared_ptr<trajectory_msgs::msg::JointTrajectory> trajectory_msg);
  	JOINT_TRAJECTORY_CONTROLLER_PUBLIC
  	bool validate_trajectory_msg(const trajectory_msgs::msg::JointTrajectory & trajectory) const;
  	JOINT_TRAJECTORY_CONTROLLER_PUBLIC
  	void add_new_trajectory_msg(
  	const std::shared_ptr<trajectory_msgs::msg::JointTrajectory> & traj_msg);
  	JOINT_TRAJECTORY_CONTROLLER_PUBLIC
  	bool validate_trajectory_point_field(
  	size_t joint_names_size, const std::vector<double> & vector_field,
  	const std::string & string_for_vector_field, size_t i, bool allow_empty) const;

• turn compute_error_for_joint into a proper function & unit test [JTC] Convert lambda to class functions #945
• if "RealtimeSubscriber" existed with an API to check for new message & get message that'd make this very readable

  ros2_controllers/joint_trajectory_controller/src/joint_trajectory_controller.cpp

  Lines 164 to 165 in 4c6d723

  	auto current_external_msg = traj_external_point_ptr_->get_trajectory_msg();
  	auto new_external_msg = traj_msg_external_point_ptr_.readFromRT();

• Convert assign_interface_from_point into member function [JTC] Convert lambda to class functions #945