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Dunder Doc

by Valdir Stumm Jr

Counting With Redis Sorted Sets

I’ve used Redis as a cache layer multiple times in my career. Most of the times, all I needed was a fast storage where I could store pre-computed JSON data and retrieve it by key. Redis was just perfect for that. Lightweight, easy to use, good docs, widely available in Cloud providers, etc. A couple weeks ago, though, I was faced with a different problem that helped me learn Redis a little more in depth.

Translation Tables In Python

Back when I was a teacher, I used to ask my students to implement a Caeser Cipher encoder/decoder. If you’re not familiar with it, it is a simple substitution cipher that replaces characters on a string by the corresponding characters from a shifted alphabet. The algorithm takes a numerical cipher n as its input (the key) and then rotates the letters in the alphabet by n characters. Then, a translation table is created by lining up the original and the rotated alphabets.

How Does CPython Multiply Big Numbers?

I am used to write code that multiplies numbers several times a week. Usually when I do that, I don’t think much about the operation itself or how the machine will execute it. But if we start thinking about it, how in hell can the CPython interpreter multiply numbers as large as the ones below? The CPU definitely does not support huge numbers like that out of the box, so how does it work?

How I manage Virtualenvs with Pyenv

I have always been a happy virtualenvwrapper user, but I abandoned it last year to use pyenv and pyenv-virtualenv. I don’t really remember why, as virtualenvwrapper is awesome. The problem is that lately I haven’t been creating and managing a lot of virtualenvs, so I often find myself having to search through pyenv docs to do basic stuff when needed. That’s why I wrote down the usual steps that I follow so that next time I can remember (or find) more easily.

Stop writing for the audience

I’ve been blogging for a long time already, but lately I noticed that it has been becoming harder and harder to finish a blog post. I have an idea, I write a draft, but in many cases the blog post never gets published. I recently realized that the further I get into writing a blog post, the bigger my anxiety on writing something perfect gets. That’s mostly because my mind gets swamped with questions like:

Black formats my code, and maybe it should format yours too

I’ve always been a bit skeptical about code formatters. I don’t know, I always felt like they would curb my freedom to format the code in my own way. Because, you know, no one formats code better than me. 😛 Joking aside, I got to know black about 2 years ago. Everyone was talking about it. A bunch of people adopted it. Massive codebases were being reformatted daily. It was the new kid on the block.

Handling Headers-Based Pagination on APIs with Python

The other day I was building a Python script to fetch some information about all my repositories on GitHub. Their API is pretty straightforward and well documented. Fetching my repos was as simple as: >>> import requests >>> response = requests.get("") The thing is that such request gave me a list with all my repos on it. No info on pagination whatsoever on the response body. After a bit of research, I found out that GitHub APIs take advantage of the Link header to expose several pagination options.

CPython Optimizations

CPython is the reference implementation of the Python language. While there are several other implementations, CPython is by far the most popular one. These days, it comes bundled in most of the operating systems. Even though CPython is not the most performatic Python interpreter out there, it does some very interesting optimizations to speed itself and Python programs up. I am pretty curious about things like these and the rationale behind them, even though I know very little about it.

My Favorite IPython Tricks

It’s no secret that IPython is my favorite Python shell. I am the guy who is always asking everyone “did you try IPython already?” as soon as I see they opening the regular Python shell. Yes, I know, you’d probably hate me. The reason I like it so much is that IPython makes it very easy for me to incrementally experiment when coding. I consider experimentation to be a crucial step when writing software, as it helps to reduce the unkowns in a problem or technology.

Tips for boosting your Python scripts

I find myself writing quick command line scripts every so often. They usually automate a random task from my daily routine and end up saving me a bunch of time. These scripts usually start as quick and dirty snippets, but once I figure that they are not a one-off thing, then I iterate to make them more usable. There are several things that I find valuable in scripts like these: