Problem 2 (200pts): Build Tunnel

In this problem, you'll complete Place.__init__ by adding code that tracks entrances. Right now, a Place keeps track only of its exit. We would like a Place to keep track of its entrance as well. A Place needs to track only one entrance. Tracking entrances will be useful when an Ant needs to see what Bees are in front of it in the tunnel.

However, simply passing an entrance to a Place constructor will be problematic; we would need to have both the exit and the entrance before creating a Place! (It's a chicken or the egg problem.) To get around this problem, we will keep track of entrances in the following way instead. Place.__init__ should specify that:

  • A newly created Place always starts with its entrance as None.
  • If the Place has an exit, then the exit's entrance is set to that Place.

Hint 1: Remember that when the __init__ method is called, the first parameter, self, is bound to the newly created object.

Hint 2: Try drawing out two Places next to each other if things get confusing. In the GUI, a place's entrance is to its right while the exit is to its left.

Hint 3: Remember that Places are not stored in a list, so you can't index into anything to access them. This means that you can't do something like colony[index + 1] to access an adjacent Place. How can you move from one place to another?

colony-drawing

Before writing any code, unlock the tests to verify your understanding of the question:

$ python ok -q 02 -u

Once you are done unlocking, begin implementing your solution. You can check your correctness with:

$ python ok -q 02