Launch file setting a deprecated param?

[artivis]

Hello,

Looking at the launch file it seems to be setting a dev parameter for the joy_node that doesn't exists. Instead, the joy_node uses device_id, since, afaict, its port to ROS 2.
Am I missing something or has this been broken forever in ROS 2?

[clalancette]

Am I missing something or has this been broken forever in ROS 2?

It hasn't been broken forever, but it has been broken quite a while. The history of the node to control joysticks in ROS 2 is a little twisted. The story below probably isn't all that relevant, but it is fun to walk down memory lane a little.

The original code of any kind of joystick control to ROS 2 was in 2016 as part of the turtlebot2_demo repository. That code was written from scratch to look at the /dev/input/js0 input device from Linux. This is equivalent in spirit to how the joystick driver in ROS 1 works, but is a very different and simplified implementation. It doesn't have any parameters at all; everything is hard-coded.

That code eventually got split out into its own repository in joystick_drivers_from_scratch. This also didn't have any parameters at all, everything is hard-coded.

Somewhat in parallel with joystick_drivers_from_scratch, joystick_drivers was forked off of the original https://github.com/ros/joystick_drivers, and a full port to ROS 2 was done. That version did have parameters, and the parameter in question was indeed called dev. It was around this time that the launch file here in teleop_twist_joy was created. At that time, the parameter was correct.

In 2020, I decided that we needed a cross-platform joystick driver, particularly one that would work in Windows. So I wrote an entirely new version based on SDL, which is the node we call "joy" today. That one was contributed to the upstream https://github.com/ros/joystick_drivers, and the old https://github.com/ros2/joystick_drivers and https://github.com/ros2/joystick_drivers_from_scratch were both deprecated. One other thing to note here is that I wasn't entirely confident that my SDL port would be sufficient, so retained the old, Linux-only joystick driver as "joy_linux". The new "joy" node uses the device_id parameter, while the old "joy_linux" node uses the dev parameter.

All of that said, you are correct that nowadays that parameter should indeed be changed to device_id. If you'd like to submit a pull request, I'd be happy to review it.

[clalancette]

This was fixed by #52 , so closing.