There is one magical thing you need to know when reading this book: It's all personal opinion
A lot of stuff I'm going to discuss throughout this book will come directly from my personal experience in several projects -- system applications, web backend, embedded, mobile, stream processing -- in several different languages -- C, C++, Python, Java, Clojure, Rust. And, because it comes from personal experience, everything reflects my own personal opinion on several subjects.
Obviously, you don't need to agree with every single point. But I hope at least it will make you rethink a few subjects.
Also, sometimes I may mention some examples that people who know me -- either worked with me, heard me complain about some project, inherit one of my projects, I inherit one of the their projects -- may recognized and think I'm attacking the author.
I am not.
We do mistakes. Sometimes we don't know the topic with are attacking, sometimes we don't have full specs, sometimes we don't have the time to write things properly in a crunchtime. And that's why some things don't look as pretty as they should. Heck, if you think I'm attacking the original author of some example, look back the stuff I wrote and you'll see things a lot worse.
But I need the example. I have this hope that showing people a few mistakes can make things better. I want to show people how my opinion built over some subject. And, again, I'm in no way attacking the original author of the code. I may even call the code "stupid", but I'm not calling the author stupid.
With that in mind...