Software Design in Python - From Spaghetti Code to Clean Python

💡 Learn how to design great software in 7 steps: https://arjan.codes/designguide. Untangling deeply nested if/else logic is one of the hardest parts of working in real-world Python codebases. In this video, I take a brutally messy example full of indentation, duplicated conditions, and hidden business rules, and systematically break it down into clean, readable logic. You’ll see how to write characterization tests to protect the existing behavior, how to flatten the structure using guard clauses, how to simplify and combine conditions, and how to deal with special cases like admin overrides without breaking anything. By the end, you’ll understand exactly how to transform complicated boolean logic into code that’s easy to read, easy to test, and easy to extend. 🔥 GitHub Repository: https://git.arjan.codes/2025/logic. 🎓 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 0:48 Why Code Like This Happens 2:57 Write Characterization Tests (Your Safety Net) 6:04 Flatten the Nesting with Guard Clauses 11:26 Remove Unnecessary Try/Except Blocks 13:10 Simplify and Name Conditions 15:26 Simplify Loops and Comprehensions 16:28 Merge Duplicate Logic 19:07 Move Rules to Data 22:01 Final Thoughts #arjancodes #softwaredesign #python