This Python peculiarity can lead to some unexpected behavior of your programs. — Say, you want a function that appends some data to a list. And if the list is not passed, then appends the same data to a newly created list. What would be the obvious and naive way to go? Sure, why not use default arguments here? …

Passing a QR code as an SVG code This tiny project will generate a QR code for any text and pass it to the HTML template as an SVG code. SVG is a very convenient medium for URLs or other text. This small demo demonstrates a few things: How to…

How much faster is your app with indexes? — Even “Senior” developers often forget to use indexes in Django. You can’t imagine how faster it can get if you simply add two lines of code into your model! In this article we will take measurements together: with and without indexes. Setup Our patient will be a small Django application with…

Step by step guide to writing Tetris in Python with PyGame In this tutorial, we will write a simple Tetris using the PyGame library in Python. The algorithms inside are pretty simple but can be a little challenging for the beginners. We will not concentrate on PyGame mechanics too much…

How to implement a rating mechanism in Django This is a short article on how to create a simple interactive Start Rating mechanism in Django. What we want to do here is to allow each user to rate a post, and there should be no more than 1 vote for…

Not only for Interviews! Motivation Some people ask if LeetCode is useful when you already have a job. Is it designed for interviews only? And replying something like “no, you learn some algorithms that are used in real life” is weird because you never reverse a queue in your Projects. And…

How do you add several items to the shopping cart? Django Admin is pretty powerful when it comes to CRUDing data. One of the features many (even experienced) developers have no idea about is having multiple many-one or many-to-many rows on the same page as on this picture: Mind-blowing, isn’t…

Also, how Decimals work with PostgreSQL Introduction When you deal with any kind of assets, be that USD or BTC, you must be sure that not a single penny is lost. What happens if the customer of your bank has 0.1 USD on his account? We need to somehow store a…

The difference between frozen and non-frozen dataclasses. — The philosophy behind the frozen classes is pretty interesting. We will start with an example of a normal, non-frozen, dataclass in Python that represents a Bank Account. Then we will transform it into a frozen class and discuss the difference. A normal mutable Dataclass So, we create a Bank Account so that we can…