Every Friday, you'll get a recap of the most important and exciting Python and coding news. The Friday Loop also keeps everyone posted on new ArjanCodes courses and any limited offers coming up.
12 Must-Know Python Built-in Functions | Issue #43
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The Friday Loop
Every Friday, you'll get a recap of the most important and exciting Python and coding news. The Friday Loop also keeps everyone posted on new ArjanCodes courses and any limited offers coming up.
AI can write code now. But you already knew that :). If you’ve tried using AI seriously, you’ve probably noticed something: the code works (kind of) and then slowly turns into a mess. In this week’s video, I show why prompting alone isn’t enough and why software design is becoming more important, not less, in an AI-driven world. I walk through a real interaction with an AI coding assistant and show how thinking in terms of responsibilities, structure, and system boundaries completely changes...
In a recent video on refactoring complicated business logic, I managed to introduce several subtle errors. Many of you immediately spotted them in the comments. That’s exactly what my first video in 2026 is about. I walk through the mistakes I made, explain why they happened, and show how easy it is to accidentally change behavior when you refactor code. Even with tests in place and decent coverage, assumptions can sneak in, business rules can shift, and logic can quietly break without anyone...
You’ve tested the endpoint. The response looks right. No errors in the terminal. So you’re done, right? Well... not quite. In the last video of this year (time flies!) I start with a tiny FastAPI app that "works", and step by step, I turn it into something that’s actually ready for production (and that's more work than you think). That includes: Proper type usage Input validation and error handling Configuration management Rate limiting to prevent abuse ...and more! All using a real example:...