1. Who is Reeborg?

Life-size Reeborg in New Jersey, USA.

Photo courtesy of A. Judkis.

Reeborg is a programmable robot; not a modern high quality robot, but a rather old one, put together rather quickly. You are going to be a good programmer, unlike the maker of Reeborg, who wrote created a faulty robot.

1. Reeborg has an oil leak. Oil leaks are damaging for the environment and inconvenient for Reeborg who must replenish its supplies when it’s not busy accomplishing tasks. The maker of Reeborg claims that it is a feature, as it enables you to follow Reeborg’s path, just like any programmer can learn to “trace” a program. There are ways to fix Reeborg’s leak ... hopefully you will learn how to do so.
2. Reeborg’s steering mechanism is not handled properly by Reeborg’s program: it can only turn left. The maker of Reeborg, once again, claims that this is a feature as it present you with an opportunity to learn about functions. Reeborg disagrees. Indeed, by defining a simple Python fuction, it is possible to program a workaround solution, enabling Reeborg to turn right, although in a wasteful fashion. Using more advanced Object-Oriented techniques, it is possible to fix this flaw properly, once and for all.
3. Reeborg has a compass, enabling him to determine which direction he is facing. Unfortunately, yet again, the program that enables Reeborg to get the information from the compass has a bug: it only tells Reeborg if he is facing North ... or not. Once again, you can learn how to implement a workaround solution and later how to fix permanently Reeborg and get rid of what its maker calls a “feature”.
4. Reeborg can see if a wall is in front of him, and can also turn its head to the right to see if there is a wall there. However, a software “glitch” (which is another weasel term that software manufacturers use to avoid having to say that their product has a bug) prevents Reeborg’s program from properly registering a wall when it turns its head left.

Sometimes to find the cause of bugs, it can help to break the normal flow of the program. To this end you may do one or more of the following:

1. You can pause a program as it is running by pressing the pause button.
2. Instead of actually pressing the pause button, you can type in the instruction pause() at any point inside a program and Reeborg will pause, awaiting your permission to continue. This is similar to what people refer to as setting a breakpoint in a computer program when using a “debugger”.
3. You can step through a program, one instruction at a time, by pressing the execute one instruction and pause, or step button.
4. You can change the speed of execution at any point inside a program by instructing Reeborg to take a certain amount of time to think().
5. You can have Reeborg write some information at any given point inside a program using Python’s print() function.
6. If you click on “World info” at the top, and then click on Reeborg’s World, you can find out some information about the state of the world, including whether or not Reeborg carries any objects.
7. Finally, you can stop a program at any point by pressing the stop button; this unfortunately may not work if you create what is known as an infinite loop, outside of Reeborg’s control. If worse comes to worst, you can always just reload the web page.