Blog

If you’re not into RSS, but would like to be notified about new content (along with exclusive “director’s commentary” about what I did and why), check out my extremely low-volume Hynek Did Something newsletter.

Subclassing in Python Redux

The conflict between subclassing and composition is as old as object-oriented programming. The latest crop of languages like Go or Rust prove that you don’t need subclassing to successfully write code. But what’s a pragmatic approach to subclassing in Python, specifically?

Read more

Canonical SEO Failure

This post is less about teaching and more about schadenfreude amusement for you, and catharsis for me. It’s the story of how one unfortunate HTML tag kicked me off almost all search engines and my months-long way back. And why it didn’t matter in the end.

Read more

Semantic Versioning Will Not Save You

The widely used Python package cryptography changed their build system to use Rust for low-level code which caused an emotional GitHub thread. Enthusiasts of 32-bit hardware from the 1990s aside, there was a vocal faction that stipulated adherence to Semantic Versioning from the maintainers – claiming it would’ve prevented all grief. I will show you not only why this is wrong, but also how relying on Semantic Versioning hurts you.

Read more

Lie vs Lay

Lie and lay are infamously confusing to non-native speakers. It’s so bad that it sparked a cottage industry of click-baity articles full of sketchy ads. Since English is my third language, I stumbled a lot myself until I wrote this cheatsheet.

Read more

Waiting in asyncio

One of the main appeals of using Python’s asyncio is being able to fire off many coroutines and run them concurrently. How many ways do you know for waiting for their results?

Read more

Why You Should Document Your Tests

Some projects have the policy that all tests must have an explanatory comment – including all of mine. At first, I found that baffling. If that’s you right now, this article is for you.

Read more

Python in GitHub Actions

GitHub’s own CI called GitHub Actions has been out of closed beta for a while and offers generous free quotas and a seamless integration with the rest of the site. Let’s have a look at how to use it for an open source Python package.

Read more

Python in Production

I’m missing a key part from the public Python discourse and I would like to help to change that.

Read more

Python Packaging Metadata

Since this topic keeps coming up, I’d like to briefly share my thoughts on Python package metadata because it’s – as always – more complex than it seems.

Read more

Books That Changed My Life

People always ask for book recommendations, so here’s my list of books that changed my life in one way or another. None of them is related to tech or programming, but all affect how I think and work.

Read more

Python in Azure Pipelines, Step by Step

Since the acquisition of Travis CI, the future of their free offering is unclear. Azure Pipelines has a generous free tier, but the examples I found are discouragingly complex and take advantage of features like templating that most projects don’t need. To close that gap, this article shows you how to move a Python project with simple CI needs from Travis CI to Azure Pipelines.

Read more

The Price of the Hallway Track

There are many good reasons to not go to every talk possible when attending conferences. However increasingly it became hip to boast about avoiding going to talks – encouraging others to follow suit. As a speaker, that rubs me the wrong way and I’ll try to explain why.

Read more

Python Application Dependency Management in 2018

We have more ways to manage dependencies in Python applications than ever. But how do they fare in production? Unfortunately this topic turned out to be quite polarizing and was at the center of a lot of heated debates. This is my attempt at an opinionated review through a DevOps lens.

Read more

Python Hashes and Equality

Most Python programmers don’t spend a lot of time thinking about how equality and hashing works. It usually just works. However there’s quite a bit of gotchas and edge cases that can lead to subtle and frustrating bugs once one starts to customize their behavior – especially if the rules on how they interact aren’t understood.

Read more

Why Your Dockerized Application Isn’t Receiving Signals

Proper cleanup when terminating your application isn’t less important when it’s running inside of a Docker container. Although it only comes down to making sure signals reach your application and handling them, there’s a bunch of things that can go wrong.

Read more

On Conference Speaking

I’ve seen quite a bit of the world thanks to being invited to speak at conferences. Since some people are under the impression that serial conference speakers possess some special talents, I’d like to demystify my process by walking you through my latest talk from start to finish.

Read more

Better Python Object Serialization

The Python standard library is full of underappreciated gems. One of them allows for simple and elegant function dispatching based on argument types. This makes it perfect for serialization of arbitrary objects – for example to JSON in web APIs and structured logs.

Read more

Please Fix Your Decorators

If your Python decorator unintentionally changes the signatures of my callables or doesn’t work with class methods, it’s broken and should be fixed. Sadly most decorators are broken because the web is full of bad advice.

Read more

Conditional Python Dependencies

Since the inception of wheels that install Python packages without executing arbitrary code, we need a static way to encode conditional dependencies for our packages. Thanks to PEP 508 we do have a blessed way but sadly the prevalence of old setuptools and pip versions make it a minefield to use.

Read more

Python 3 in 2016

My completely anecdotal view on the state of Python 3 in 2016. Based on my own recent experience, observations, and exchanges with other members of the Python community.

Read more



Testing & Packaging

How to ensure that your tests run code that you think they are running, and how to measure your coverage over multiple tox runs (in parallel!).

Read more

virtualenv Lives!

Setting up Python to the point to be able install packages from PyPI can be annoying and time-intensive. Even worse are OS-provided installations that start throwing cryptic error messages. Especially desktops are prone to that but it’s possible to break the whole toolchain of a server by installing some shiny package you heard about on reddit.

Read more

Apple OpenSSL Verification Surprises

Apple ships a patched version of OpenSSL with macOS. If no precautions are taken, their changes rob you of the power to choose your trusted CAs, and break the semantics of a callback that can be used for custom checks and verifications in client software.

Read more


Life after Google Reader

Google killed its Reader and my beloved Reeder for Mac and iPad officially won’t get updated in time. I think to have found an adequate setup to replace both.

Read more


Know Your Models

In web development, we have a unfortunate double meaning for the word models and as obvious as the separation of those two seems to seasoned developers, it shows again and again that it’s not as obvious to beginners.

Read more




How I Stopped Worrying and Started Loving PyLadies

When I read about PyLadies for the first time, my thoughts were a common knee-jerk: “separation is bad, dividing the community, …”. Like many of my privileged peers, I was pro-diversity but I thought this is the wrong way. My views changed over time and I filed it under “lessons learned”. Unfortunately, my old thinking patterns don’t cease to pop up in discussions, so I decided to share my perspective.

Read more

My Road to the Python Commit Bit

Like many OSS fans, I always wanted to be an active part of the movement. My last big project was for the Amiga in the past millennium though. Nowadays I’m happy that after years of small-scale dabbling on various projects I’ve found my haven. I’d like to share my way to my recent gain of push privileges on the Python project and hope to inspire some of you to do the same.

Read more

Python Application Deployment with Native Packages

Speed, reproducibility, easy rollbacks, and predictability is what we strive for when deploying our diverse Python applications. And that’s what we achieved by leveraging virtual environments and Linux system packages.

Read more

Python Deployment Anti-Patterns

Deploying web applications is hard. No shiny continuous deployment talk and no DevOps coolness can change that. Or to use DevOps Borat’s words: “Is all fun and game until you are need of put it in production.“ There are some mistakes I see people doing again and again so I’d like to address them here.

Read more

Celery and Sybase SQL Anywhere

In our newest installation of “why you should not use Sybase SQL Anywhere” I’d like to report the latest problem I had to solve: for some reason, I couldn’t connect using sqlanydb from Celery tasks.

Read more

Fleeing from Gmail

So you came to the same conclusion as I: Google is actually evil indeed. That makes it kind of uncomfortable to have all your emails over there, doesn’t it? I for one decided that it’s time to leave and will show you how to do the same using an UNIX based OS.

Read more

My 2011

I never did a retrospective but 2011 deserves one.

Read more

Dead Simple Connection Pooling with Twisted

There is this common notion, that asynchronous IO is hard and that writing a custom connection pool is even harder. The nice thing however is, that in reality asynchronous IO is just “weird” in the beginning – and that a connection pool using async IO is so simple it hurts.

Read more

MacVim and the Clipboard

After switching to the Mac, I had one big itch that spoiled all the bliss: MacVim sometimes simply refused to cooperate with the system clipboard. As you can imagine, an editor that can’t exchange text with other software is a rather painful thing.

Read more

Why Tomatoes Are Awesome

No, this isn’t going to be a smug post about nutrition. These tomatoes I’m going to talk about aren’t for eating but for kicking my ass to be more productive. I’m talking about the Pomodoro Technique of course.

Read more

My mutt & Gmail Setup

So you want quick offline access to your mails using mutt to fully exploit your SSD and yet still have everything nicely working in Google’s web interface? Additionally, you would like to have access to your Google Contacts just like in your phone and everywhere else? I’ll show you how!

Read more



Twisted Sybase SQL Anywhere

Using the official sqlanydb driver for Python together with Twisted’s adbapi produces not-so-occasional crashes as of today (sqlanydb 1.0.2, Twisted 11.0.0). Apparently, the official SQL Anywhere drivers aren’t thread-safe. It cost me several days to figure out because I was searching the fault in my code so I hope to spare you some pain.

Read more

Django & Postgres & SSL

I’d thought something like this is a FAQ but the database docs on postgres don’t write a bit about forcing Django to connect using SSL to the database server.

Read more

Information Diet

There are few people that influenced me more than Tim Ferris. He was the one who gave me the last nudge to the low carb diet and he was also the one from whom I learned about the “Information Diet”.

Read more


Freezing Kindle

After a few months of use my Kindle started to freeze randomly. At first I blamed the cold as it happened to be winter in that moment. Fortunately, it turned out to be something different.

Read more

LDAP: A Gentle Introduction

The perception of LDAP (Lightweight Directory Access Protocol) is ambivalent. On the one hand, it is widely supported as a common authentication backend. On the other hand, there’s very little and poor documentation that is mostly targeted towards a special case (e.g. replacing NIS by LDAP).

Read more

MySQL Replication

Sounds harder than it is – especially when reading the official docs. But if you want to synchronize two DBs, just tell the “master” to write a log and slave to read it.

Read more

PCAP Format for Logs

While developing a network sniffer I had to find a way to write pcap logs. However the docs I found were rather fragmented. I try to do a short roundup here. In fact, the format is pretty plain and it’s a pity that there seems not to be a quick’n’easy doc for it.

Read more