Parameter challenge

With this challenge, you will practice everything you’ve seen in this chapter: declaring and getting parameters in your code, providing parameters’ values at runtime, and saving the values inside a YAML file. We will just skip parameter callbacks, but feel free to add them if you want to practice those too.

As usual for challenges, I will first explain what the challenge is and then provide the Python solution. You can find the complete code for both Python and C++ in the book’s GitHub repository.

Challenge

We will continue to improve the turtle_controller node. For this challenge, we want to be able to choose different settings at runtime:

• Pen color on the right side
• Pen color on the left side
• Velocity to publish on the cmd_vel topic

To do that, you will add these parameters:

• color_1: Instead of just arbitrarily choosing a color for when the turtle is on the right side, we rename the color as color_1...