Oct 30: Immutability, Aliasing

Meet in EnGeo 2208

Learning Objectives

After today's class, you should be able to:

• Explain why a string method returns a new string.
• Contrast strings with lists, which can be changed in place.
• Predict what happens to a list modified inside a function.

Lesson Outline

Presentation [10 min]

• Review of lists, dictionaries, and files
• Python Reference Sheet provided on Quiz 4

Mini Lecture [25 min]

• Python Tutor
  • Passing strings and lists to functions
  • Objects (boxes) + references (arrows)

Q4–Q6 [15 min]

4. Building with a loop
5. Counting with a dict
6. Reasoning about pytest

Your To-Do List

• Required before Monday's class:
  • PA3: Gift Swap  OR  PA3: Trivia Night
  • Submit to Gradescope until you get 100%
  • Don't use AI; visit TA Hours to get help
• Have a safe and Happy Halloween! 🎃 👻