The Memento Pattern: Saving State Without Breaking Encapsulation

👨🏻‍💻 Join me in Utrecht next year for an in-person Software Design Retreat! Design, discuss, and learn alongside fellow developers. Join the waitlist: https://arjancodes.com/retreat. 🧱 Build software that lasts. Join the Software Design Mastery program → https://arjan.codes/mastery. Undo sounds simple until every change needs its own reverse logic. The Memento pattern offers a different approach: save an object's state and restore it when you need to go back. In this video, I show how to implement the Memento pattern in modern Python using snapshots, dataclasses, protocols, and generics. 🔥 GitHub Repository: https://git.arjan.codes/2026/memento. 💬 Join my Discord server: https://discord.arjan.codes. ⌨️ Keyboard I’m using: https://amzn.to/49YM97v. 🔖 Chapters: 0:00 Intro 1:20 The Workflow 2:40 Take a Snapshot 6:08 Originator, Memento, and Caretaker 11:02 What Should Be in the Snapshot? 12:03 Undo and Redo 13:12 Memento vs Command 14:01 Beyond Undo 14:35 When Not to Use It 15:07 Final Thoughts #arjancodes #softwaredesign #python