Cleanup all the deprecations warning from the recent ros2_control variant changes

[saikishor]

Background

Recently after the new variants feature in Handles (ros-controls/ros2_control#1688) We have a bunch of deprecation warnings that needs to be cleanup. This could be a nice first issue.

Instructions

The best approach to this is to create the temporary variables where ever needed and then if the set_value or get_value returns False. Then, better to print a warning and simply return OK. This way, if we have some failures in getting data, the user will be able to know and can introspect properly.

Moreover, If everything is running synchronously. it should work as expected without any failures.

For example:

For the following lines of the code in the diff_drive_controller:

ros2_controllers/diff_drive_controller/src/diff_drive_controller.cpp

Lines 268 to 272 in 81c0d41

	for (size_t index = 0; index < static_cast<size_t>(wheels_per_side_); ++index)
	{
	registered_left_wheel_handles_[index].velocity.get().set_value(velocity_left);
	registered_right_wheel_handles_[index].velocity.get().set_value(velocity_right);
	}

The expected code should look like:

  for (size_t index = 0; index < static_cast<size_t>(wheels_per_side_); ++index)
  {
    if (!registered_left_wheel_handles_[index].velocity.get().set_value(velocity_left) ||
    !registered_right_wheel_handles_[index].velocity.get().set_value(velocity_right))
    {
      RCLCPP_WARN(get_node()->get_logger(), "Error while setting the velocity_left : %f "
        "and velocity_right : %f to the command handles", velocity_left, velocity_right);
      return controller_interface::return_type::OK;
    }
  }

For the following get_value code in the diff_drive_controller:

ros2_controllers/diff_drive_controller/src/diff_drive_controller.cpp

Lines 162 to 164 in 81c0d41

	const double left_feedback = registered_left_wheel_handles_[index].feedback.get().get_value();
	const double right_feedback =
	registered_right_wheel_handles_[index].feedback.get().get_value();

The expected outcome would be:

bool left_success = false;
const double left_feedback = [&]() {
    double temp;
    left_success = registered_left_wheel_handles_[index].feedback.get().get_value(temp);
    return temp;
}();

bool right_success = false;
const double right_feedback = [&]() {
    double temp;
    right_success = registered_right_wheel_handles_[index].feedback.get().get_value(temp);
    return temp;
}();

// Now you can use left_success and right_success to check if get_value was successful
if (!left_success || !right_success) {
    RCLCPP_WARN(get_node()->get_logger(), "Error while fetching information from the state interfaces");
    return controller_interface::return_type::OK;
}

or

double left_feedback, right_feedback; 
if(!registered_left_wheel_handles_[index].feedback.get().get_value(left_feedback) ||
    !registered_right_wheel_handles_[index].feedback.get().get_value(right_feedback))
{
  RCLCPP_WARN(get_node()->get_logger(), "Error while fetching information from the state interfaces");
  return controller_interface::return_type::OK;
}

May be the first approach is better as it retains the const ness of the variable

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🤔❓ Questions?

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• ROS2 Control Contribution Guide
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Good luck with your first issue!

[saikishor]

@kumar-sanjeeev or @MartinPeris you might be interested to work on this

[kumar-sanjeeev]

@saikishor, thanks. I will look into this.

[kumar-sanjeeev]

@saikishor Hi,

I took a look at this and made adjustments to the diff_drive_controller code to capture and handle the return values of the get_value and set_value where ever used. I think similar changes need to be applied to the other controllers as well? If so, do you think I should submit one PR covering all controllers, or would it be better to start with a PR for diff_drive_controller and then add commits for the others later? Let me know what you think.

[saikishor]

@kumar-sanjeeev let's try to address all these depreciations in a single PR

[christophfroehlich]

but you always can submit a draft PR if you want to get feedback before you work on the other controllers

[kumar-sanjeeev]

@christophfroehlich, yeah I would like to do that, just to check if I am in right direction or not. So I will submit draft PR.

[saikishor]

@christophfroehlich, yeah I would like to do that, just to check if I am in right direction or not. So I will submit draft PR.

Thank you!