Python Properties vs Methods: The Contract You Didn’t Know You Were Making

🧑‍💻 Join the Software Design Mastery waitlist here: https://www.arjancodes.com/mastery. In this video, I break down when something in Python should be a property and when it should be a method, and why that choice matters more than it looks. Using a simple example, I show how properties and methods communicate different promises about cost, safety, and behaviour. I’ll also look at why async properties are usually a design smell, and how to keep async work explicit without breaking clean object design. 🔥 GitHub Repository: https://git.arjan.codes/2026/props. 🎓 ArjanCodes Courses: https://www.arjancodes.com/courses. 💬 Join my Discord server: https://discord.arjan.codes. ⌨️ Keyboard I’m using: https://amzn.to/49YM97v. 🔖 Chapters: 0:00 Intro 1:17 Setup: One Example for the Whole Video (Synchronous Version) 2:29 Properties vs Methods 3:48 Derived State: A Perfect Use Case for Properties 6:14 Under the Hood: Why @property Works 6:59 Read-Only vs Writable Properties 8:58 When Setters Should N