Mutability

Jed Rembold

March 4, 2026

Happy Hump Day!

Quick Announcements

  • Breakout!
  • Sections meeting today or tomorrow. Make sure you attend!
  • I am having to move my Wed office hours from 4:30-5:30 to 2-2:40 for the rest of the semester
    • I’ll be around even longer on Tuesdays and Thursdays though
  • I’m going to be working on getting grade reports out this weekend

Daily LO’s

  • Correctly trace code working with lists where mutability matters
  • Work with and think about the id of mutable objects
  • Practice interacting with the VSCode debugger

Group Problems

Problem 1: Tracing Clues

What would the below code print out at the end?

ballroom = ['Miss Scarlet', 'Mr. Green', 'Prof Plum']
hall = ['Mrs. Peacock', 'Col. Mustard']
study = ['Mrs. White']
house = [ballroom, hall, study]
hall = hall + study
for character in ballroom:
    if character[0] == 'P':
        house[1][0] = character
print(hall)

Problem 2: The Escape

  • Work in pairs or trios on a single computer
  • At the top of the lecture content maze.py file, enter in your pair/trios names
  • The idea here is that you are plunged into a mysterious maze
  • To cast the escape spell, you need to collect three items: a spellbook, potion, and wand
  • The trick lies in finding them

Problem 2: The Maze

  • Each maze is generated custom for your group
  • Consists of connected rooms, depicted with a special MazeCell object
  • Each room has:
    • Some contents. Usually None, but sometimes one of the items you need!
    • A series of directions that reference other connected rooms (or None)

😊 ☨ 🧪 📖 N S S W E S N N S E S W S W S E E W

Problem 2: The Exploration

  • To have a chance of finding your way out, it would help to work out the layout of your maze
  • Can do so by utilizing VSCode’s debugger!
  • Place a breakpoint on the indicated line, and run the program in debug mode
  • Now you can “explore” the MazeCells by using the dropdown menu that appears
  • Construct yourself a map!
    • What room connects to what? The memory address is unique here!
    • What item, if any, is in the room?

Problem 3: Escaping!

  • Given your map, construct a set of instructions that would take you from your starting position to gather all three needed items
  • Express this series of instructions as a string of “NSEW” characters
  • Enter it into twisty function when it is called at the bottom of the program, and then run the program normally. Did you escape?!

Demo

Deep Clues?

  • Let’s have a list of clue rooms where each room has a list of individuals currently within it, like in our starting question
  • How could I properly “move” a character from one room to the next, given the tools we currently have?
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