Return std::optional in RobotDriver::get_error()

CHANGELOG.md

@@ -13,6 +13,7 @@
   broken light panels.
 
 ### Changed
+- Upgrade to robot_interfaces v2 (not yet released).
 - plot_post_submission_log.py now plots multiple log files side by side instead of
   merging them.  This is useful for comparing different robots.
   The option to merge multiple log files has been dropped but the merging can easily be

CMakeLists.txt

@@ -30,6 +30,7 @@ find_package(trifinger_object_tracking REQUIRED)
 ## System dependencies are found with CMake's conventions
 # find_package(Boost REQUIRED COMPONENTS system)
 find_package(Eigen3 REQUIRED)
+find_package(fmt REQUIRED)
 find_package(OpenCV REQUIRED)
 
 
@@ -47,6 +48,7 @@ target_include_directories(
 )
 target_link_libraries(${PROJECT_NAME} INTERFACE
     Eigen3::Eigen
+    fmt::fmt
     yaml_utils::yaml_utils
     blmc_drivers::blmc_drivers
     robot_interfaces::robot_interfaces

include/robot_fingers/fake_finger_driver.hpp

@@ -59,9 +59,9 @@ class FakeFingerDriver : public robot_interfaces::RobotDriver<
         return desired_action;
     }
 
-    std::string get_error() override
+    std::optional<std::string> get_error() override
     {
-        return "";  // no errors
+        return std::nullopt;  // no errors
     }
 
     void shutdown() override

include/robot_fingers/n_joint_blmc_robot_driver.hpp

@@ -12,6 +12,7 @@
 #include <iterator>
 #include <string>
 
+#include <fmt/format.h>
 #include <yaml-cpp/yaml.h>
 #include <Eigen/Eigen>
 
@@ -139,7 +140,7 @@ class NJointBlmcRobotDriver
 
     virtual Observation get_latest_observation() override = 0;
     Action apply_action(const Action &desired_action) override;
-    std::string get_error() override;
+    std::optional<std::string> get_error() override;
     void shutdown() override;
 
     /**

include/robot_fingers/n_joint_blmc_robot_driver.hxx

@@ -374,61 +374,43 @@ auto NJBRD::apply_action(const NJBRD::Action &desired_action) -> Action
 }
 
 TPL_NJBRD
-std::string NJBRD::get_error()
+std::optional<std::string> NJBRD::get_error()
 {
     // Checks each board for errors and translates the error codes into
     // human-readable strings.  If multiple boards have errors, the messages
     // are concatenated.  Each message is prepended with the index of the
     // corresponding board.
 
-    std::string error_msg = "";
+    std::optional<std::string> error_msg = std::nullopt;
 
     for (size_t i = 0; i < motor_boards_.size(); i++)
     {
         auto status_timeseries = motor_boards_[i]->get_status();
         if (status_timeseries->length() > 0)
         {
-            std::string board_error_msg = "";
+            std::string_view board_error_msg = "";
             using ErrorCodes = blmc_drivers::MotorBoardStatus::ErrorCodes;
-            switch (status_timeseries->newest_element().error_code)
-            {
-                case ErrorCodes::NONE:
-                    break;
-                case ErrorCodes::ENCODER:
-                    board_error_msg = "Encoder Error";
-                    break;
-                case ErrorCodes::CAN_RECV_TIMEOUT:
-                    board_error_msg = "CAN Receive Timeout";
-                    break;
-                case ErrorCodes::CRIT_TEMP:
-                    board_error_msg = "Critical Temperature";
-                    break;
-                case ErrorCodes::POSCONV:
-                    board_error_msg =
-                        "Error in SpinTAC Position Convert module";
-                    break;
-                case ErrorCodes::POS_ROLLOVER:
-                    board_error_msg = "Position Rollover";
-                    break;
-                case ErrorCodes::OTHER:
-                    board_error_msg = "Other Error";
-                    break;
-                default:
-                    board_error_msg = "Unknown Error";
-                    break;
-            }
 
-            if (!board_error_msg.empty())
+            if (status_timeseries->newest_element().error_code !=
+                ErrorCodes::NONE)
             {
-                if (!error_msg.empty())
+                board_error_msg =
+                    blmc_drivers::MotorBoardStatus::get_error_description(
+                        status_timeseries->newest_element().error_code);
+
+                if (error_msg)
+                {
+                    *error_msg += "  ";
+                }
+                else
                 {
-                    error_msg += "  ";
+                    // initialise
+                    error_msg = "";
                 }
 
                 // error of the board with board index to the error message
                 // string
-                error_msg +=
-                    "[Board " + std::to_string(i) + "] " + board_error_msg;
+                *error_msg += fmt::format("[Board {}] {}", i, board_error_msg);
             }
         }
     }
@@ -437,12 +419,17 @@ std::string NJBRD::get_error()
     Vector position = this->joint_modules_.get_measured_angles();
     if (!config_.is_within_hard_position_limits(position))
     {
-        if (!error_msg.empty())
+        if (error_msg)
+        {
+            *error_msg += " | ";
+        }
+        else
         {
-            error_msg += " | ";
+            // initialise
+            error_msg = "";
         }
 
-        error_msg += "Position limits exceeded.";
+        *error_msg += "Position limits exceeded.";
     }
 
     return error_msg;

include/robot_fingers/pybullet_driver.hpp

@@ -112,9 +112,9 @@ class BasePyBulletFingerDriver
         return applied_action;
     }
 
-    std::string get_error() override
+    std::optional<std::string> get_error() override
     {
-        return "";  // no errors
+        return std::nullopt;  // no errors
     }
 
     void shutdown() override