The Value Object Pattern: The Most Underrated Design Tool in Python

🧱 Build software that lasts. Join the Software Design Mastery waiting list → https://arjan.codes/mastery. In this video, I show how to use the Value Object pattern in Python to model prices, percentages, and email addresses properly. I’ll enforce invariants once, eliminate ambiguity (is 0.2 equal to 20%?), and make invalid states hard to represent, without adding unnecessary complexity. 🔥 GitHub Repository: https://git.arjan.codes/2026/value. 🎓 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 1:44 Primitive Obsession (The Actual Problem) 2:30 The “Before” Example (Looks Fine, Isn’t) 3:10 What a Value Object Actually Is 3:47 Price as a Value Object (Behaves Like a Float) 5:39 Percentage as a Value Object (Kills Ambiguity) 7:27 Keep Business Logic as a Function 10:27 Second Example: EmailAddress as a Dataclass Value Object 12:03 Quick Mention: Pydantic 12:3