Add minimal rclpy timer example demonstrating create_timer() usage

[yadnyeshwar]

This PR adds a minimal example demonstrating how to use
create_timer() in rclpy.

While the minimal publisher example already uses a timer internally,
this example focuses specifically on timer usage without publishing.

This provides a simple reference for beginners learning
periodic execution in ROS 2.

Closes #436

[alsora]

Adding the python file is not sufficient.

you should create a package so that the script can be "built" and installed, and then run via ros2 run

[fujitatomoya]

@yadnyeshwar this is requested changes, friendly ping.

[yadnyeshwar]

@yadnyeshwar this is requested changes, friendly ping.

Thank you for the reminder and apologies for the delayed response. I was away for a short period due to personal reasons.

I have now addressed the requested changes by converting the example into an installable ROS 2 Python package so that it can be built and executed via ros2 run. I am currently verifying the CI results and will follow up with any additional fixes if needed.

Please let me know if there are any other adjustments you would like me to make.

[alsora]

this still requires work.

• there are two identical copies of the script (one under timers and one under topics)
• the new files (setup, package, etc) were added to the topics folder rather than to the timers folder, where they should be.

[dlanov]

This PR appears to have been inactive since April, and the remaining review feedback looks narrowly scoped: remove the duplicate timer script and keep the complete installable package under rclpy/timers/minimal_timer. Are you still planning to update it? If not, I would be happy to prepare a clean rolling PR that preserves the example and addresses those points.

[yadnyeshwar]

This PR appears to have been inactive since April, and the remaining review feedback looks narrowly scoped: remove the duplicate timer script and keep the complete installable package under rclpy/timers/minimal_timer. Are you still planning to update it? If not, I would be happy to prepare a clean rolling PR that preserves the example and addresses those points.

Hi @dlanov , thank you for following up. I'm still interested in completing this contribution and continuing to contribute to ROS 2. I've been reviewing the current state of this PR against the latest rolling branch and noticed that the repository structure has changed since the original review. Before updating the branch, I'd like to confirm whether you would still prefer the installable package to live under rclpy/timers/minimal_timer as mentioned in the earlier review, or if you'd prefer the PR to follow the current repository layout. I'm happy to update the PR accordingly. Thank you!

[dlanov]

@yadnyeshwar
Thanks for confirming. I'll step back and leave the layout decision and next update to you and the maintainers.