ArjanCodes — transcripts.

1The Right Way to Use AI for Writing Maintainable CodeToday I'm going to show you how to properly direct an AI to write code for you. And in my opinion, not enough people are doing this. What I show you will massively improve the… 2I Tried SOLID Principles in Python… Here’s What HappenedThis video is brought to you by Squarespace. You may have heard of the solid design principles. In fact, you may have heard of them from an old video done by me. Robert Martin… 3Stop Checking for None EverywhereHere's a drone delivery function that tries to assign a route. The problem here is that this is riddled with non values and non checks. Now, this example I kind of overdid it, but… 4Stop Hardcoding Everything: Use Dependency InjectionHere we have code example of a simple data pipeline that loads data and then does some transformation and then exports it again to JSON. Now, currently all of this is hardcoded in… 5Your REST API Needs WebhooksTake a look at this API endpoints. What this is is a simple URL shortener. Basically, somebody clicks a link. We then increment a counter, so we track how many clicks there are… 6You Don’t Need That Design PatternHere's Python script that summarizes text that uses an LLM and it also has a couple of design patterns. For example, there's a prompt strategy, which is an abstract base class. It… 7Don’t Use Boolean Flags in Python, Use Policies InsteadHere's a function that I see all the time in real Python code. There are a few flags, some if statements. It actually looks fine uh until you add one rule and you add another one… 8Python Properties vs Methods: The Contract You Didn’t Know You Were MakingLook at these two user account classes. Aren't they beautiful? No, they're not really beautiful. But as you can see, the main difference is that here, this one has a method and… 9Stop Overwriting State And Use Event Sourcing InsteadImagine in a game your player's inventory shows three swords, two bows and a banana, but you have no idea how they got there. In particular, where did the banana come from? The… 10Your API Can’t Handle Real-World IntegrationsLet's say you build a nice REST API product, but then you release it and you find out your customers can't integrate it with their own systems. One customer needs a CRM ID… 11The Real Reason the Singleton Pattern ExistsSingletons are an antiattern. You've probably heard this before. The reason is that it introduces global shared state. And yeah, that's dangerous. But there's another often… 12From Spaghetti Code to Clean PythonTake a look at this mess. This is a function that approves an order for a particular user. As you can see, there's like a bunch of if else statements here. Uh orders, currencies… 1310 Powerful Python Modules You’re Probably Not UsingPython's standard library is crazy powerful. Most people know about JSON or OS, but there are modules that can save you hours of work and you're probably not using them. Today… 1410 Python Features You’re Not Using (But Really Should)Here's a CSV file with millions of sales records. And here I have a function that reads the file and computes the total sales amount. Now, when I run this, you see that every time… 15How to Write Python That Feels Like PythonThe code that you're seeing here works but it's ugly, repetitive, for both totally unpythonic. Today, I'm going to take this pretty clunky fitness tracker script and refactor it… 16I Made a Classic Refactoring MistakeIn my video covering refactoring complicated business logic, I made some mistakes which you noticed in the comments section. Well spotted, by the way. I want to go over them in… 177 Things You Didn’t Know Dataclasses Could DoMost developers know the basics of data classes in Python. You define a simple class with some typed fields and then Python generates the boiler plate. Here you see an example of… 18You’ve Been Underusing Dataclasses (These Tricks Are Wild)Do you see that in it far thingy there? Do you know what that actually is? It looks like a field, but it's actually something else. I'll explain later on. Today, I'm going to show… 19Too Many Function Arguments? Use This PatternDo you ever feel like you're just passing the same five arguments through every function in your code? You could use a singleton to try to fix that, but that's not really… 20Why “Clean Code” Often Creates Worse DesignsThis code looks pretty clean, right? There is a nice interface here. We're using a protocol. There is a container. Uh we can call a method and use different options. In this case… 21CQRS in Python: Clean Reads, Clean WritesLet's say you're doing customer support for OpenAI and you want to compute some data to get an idea of how broken your product is, but your API is a bit limited and can only… 22My 4 Favorite Python 3.14 FeaturesPython 3.14. Python, it's here. Ah, I've been waiting for this my whole career. Python. Oh my goodness. But I'm also a bit sad because now what do we wait for? Version 3.162 the… 23The State Pattern Done the Pythonic WayHere's an implementation of the traditional state design pattern using classes and inheritance. I have a payment state protocol class. So at least slightly modern and it is the… 24The Best Way to Share Code Between Python AppsIf you're managing multiple Python apps in one project, one repository, that can be quite messy. You'll have multiple virtual environments, log files, different versions of… 25This Design Pattern Scares Me To DeathThis is a video about the specification design pattern with a big warning. It's extreme overengineering. I wasn't even sure whether I should actually post this video. The reason… 26Python Has Serious Problems, But I Use It AnywayConfession time. I used to not like Python at all and now I run a pretty big Python focused YouTube channel. So either I completely changed my mind or perhaps something more… 27I’m done with the AI hype[sighs and gasps] >> I'm done with AI hype. Now, I know this may sound like an old man yells at clouds video. I mean, I am old and AI agents live in the clouds, so there's that… 28DRY Often Makes Your Code WorseHere's some example code for normalizing email addresses and usernames. Uh there's two functions here that do that job. And I have a main function that has a bunch of email… 29Stop Mixing FastAPI with Business Logic: Fix It with Ports & AdaptersHere's an example of a fast API app for placing orders. And this is the endpoint. Uh this internally calls a place order function that gets a database connection store keeping a… 30Let’s Fix Bloated Python Classes Once and For AllThis churn experiment class looks reasonable at first. It stores some data configuration things. It owns a model and it has a run method that runs a particular experiment. But… 31Beyond Pandas & NumPy: 14 Python Libraries to TryToday I'm going to explore 14 Python libraries that you probably haven't used, but you should. And at the end I'll include a bonus one. It's not a library, but it's really nice… 32The Lazy Loading Pattern: How to Make Python Programs Feel InstantI have a script here that loads data from a pretty large CSV file. As you can see, there's like millions of records in here. Now, I'm doing this in a pretty naive way. I'm simply… 33Stop Passing Primitives Everywhere (Use Value Objects)Here's an example of code that deals with prices and discounts. As you can see, I'm using a primitive type here to represent those things, floating points in this case. Now, the… 34UV Just Got A Serious UpgradeIf you've ever felt Python dependency management is slow, fragile, just clunky, UV has been evolving fast to fix that. In this video, I'll walk you through how UV works, how to… 35Anatomy of a Scalable Python Project (FastAPI)Today I'm going to show you the anatomy of a scalable Python project. Here you see what my project looks like. This is basically the setup that I use for all my production… 36Avoid Messy Code: Design Patterns for AI Agents in PythonThis video is brought to you by Squarespace. If you're trying to build something with large language models, you know things can get messy pretty quickly. You start with one… 37Learning Python Feels Easy. Until It Isn’t.Python is by far the most popular programming language in the world right now. If you look at the tobi index, the difference especially since past few years is staggering. It's… 38The Hidden Mechanism Behind Clean Python APIs (Descriptor Deep Dive)If you've used something like at property in Python, you have used descriptors. Today, I'll dive into what descriptors are. I'll show you a couple of cool things you can do with… 39What Most Python Developers Miss About GeneratorsHere's a simple Python function that processes log lines. When you run this, you see something interesting. Producing and consuming are interled. And that means that this function… 40Retry Pattern: The Secret to Resilient Python CodeHere's an example of piece of code that calls the Chuck Norris API to retrieve a random joke. Let's run this and see what happens. Oops, that's a crash. Let's try this again. Ah… 41Too Many Parameters? Use This PatternHis function that searches for videos, but as you can see it has collected quite a few parameters over time. And that's normal that it happens. As your code evolves, you're going… 42The Builder Pattern in Python: Finally Explained!Sometimes creating an object gets messy. If you have a config file, a report, a database query, or even a simple HTML page, all need a ton of options, flags, and nested parts. And… 43We need to talk.something is likely holding you back from reaching your full potential. And this is something that I've struggled with my whole career. And I've seen many other developers do it… 44AI Writes Code Faster Than You. Now What?A couple of weeks ago, I posted a video saying I was done with the AI hype. Many of you commented on that video and shared your thoughts, which I thought was really interesting to… 45Nested Loops Aren’t the Problem. This Is.You've probably seen code like this. Uh, basically a bunch of nested loops and if statements. Now, this code does work. As you can see, both Alice and Bob placed one order and… 46Build Production-Ready AI Agents in Python with Pydantic AIThis video is brought to you by Squarespace. What if you could integrate GPT4 right into your Python app and make it aware of your business logic, your data, and your models?…