Ten books that shaped me as a software developer – Part I (Books 0 to 4)

Last week, I’ve done a question and answers event with students when the question came up what the most influential books were that I have read as a software developer. I couldn’t answer the question right away but promised to compile the list with short descriptions of the book’s influence. And here it is – my list of books that left a big mark in my day-to-day work. Others have done the list of books thing before me, and most lists contain the same books over and over again. I take it as an indicator that my list isn’t too far off.


Before I start the list, I want to say a few things. The list isn’t ordered or ranked. I describe the effects of each book from my current standpoint, sometimes 20 years after the fact. I read a lot more good, interesting and inspiring books in the last 20 years and they all added to my work personality. But with all the books on my list, I felt enlightened and vibrant with new ideas. They didn’t just inspire me, they elevated my thinking. And because of this criteria of immediate improvement, one book is missing from the list. It’s the first “serious” software development book I’ve ever read in 1998: “Design Patterns. The book was just too much for me (and my study group peers) to handle such early in our careers. We were in our first year of study and had a lot of other battles to fight. I crossed it from my reading list and moved on. Years later, I re-read it and saw so much insight I plainly missed the first time, but gathered elsewhere since. If you want to read this classic, don’t hesitate! If you “only” want to know about design patterns, there’s a better book for that: “Head First Design Patterns“.

The Pragmatic Programmer

https://images-na.ssl-images-amazon.com/images/I/41BKx1AxQWL._SX396_BO1,204,203,200_.jpgMore by chance, my co-founder stumbled upon “The Pragmatic Programmer” in 1999 and devoured it. Then he gave the book to me and it shattered me to my core. I thought I was a decent software developer and here are Dave Thomas and Andy Hunt and talk about things I didn’t even knew existed. A healthy dose of Dunning-Kruger effect is crucial in everybody’s upbringing, but this book ended my overestimation once and for all and gave my studies a focus and direction I wouldn’t have thought to be possible before. I own my whole career to this book, at least in terms of work ethics. I cannot fathom how my professional life would have played out otherwise.



Also in 1999, Martin Fowler wrote his instant classic “Refactoring“. We bought this book at the first chance we got and raced through the pages. I was a Java developer back then and with most of the examples being in Java, the book needed no explanation nor translation. It was directly applicable knowledge that gave me years of experience virtually for free. This book is a must-read even 20 years later, and has just recently had the second edition announced, this time with code examples in JavaScript. I thought it was a joke first, but I guess it makes sense.

Working Effectively With Legacy Code

https://images-na.ssl-images-amazon.com/images/I/51EgCCLOWxL._SX376_BO1,204,203,200_.jpgIn 2004, Michael Feathers wrote a book that contains his 20+ years of experience with software development and named it “Working Effectively With Legacy Code“. Well, joke’s on you – I don’t write legacy code, my code is perfect. That wasn’t my attitude since 1999 (see list entry #1) and I took this book everywhere. It’s a heavy one, but I read it in the tram, right before the movie starts in cinema, during breakfast, lunch and dinner and virtually any other circumstance. I realized that reading this book will gain me experience a lot faster than actually writing code, so I just stopped for a few weeks. This book answered a lot of mysteries in the form of “is there really no better way to do this?” for me. And it introduced the concept of code seams for me that permeates my work ever since. I can clearly remember the day when I looked at my existing code again and saw the seams for the first time. It was truly eye-opening for me.

Analysis Patterns

https://images-na.ssl-images-amazon.com/images/I/41uNHkTq8NL._SX378_BO1,204,203,200_.jpgMartin Fowler was a very productive author in the late nineties. I’ve read most of his books from this period, if maybe with a few years delay. “Analysis Patterns” from 1996 arrived in my bookshelf in the early 2000’s and was my wake-up call to seeing models instead of actualities. I’ve given this book to many peers, but haven’t received the reactions that I had with this book: Being taught a language (with a graphical notation) that can express actual problems in terms of an overarching solution. Since then, I’ve seen the same solutions applied in many different forms, with many different names and a lot of different special requirements. But they all derive from the same model. This effect was promised by the “Design Patterns” book, but for me, delivered by “Analysis Patterns”. Even Martin Fowler admits that the book is showing its age, but for me, its timeless.


https://images-na.ssl-images-amazon.com/images/I/51MlUgcSICL._SX331_BO1,204,203,200_.jpgSince the late 80’s, Tom DeMarco and Timothy Lister wrote one book after the other. Each book describes a common business-oriented problem and at least one working solution for it. And yet, the very same problems still persist in the business world. It’s as if nobody reads books. “Peopleware” was written in 1987, 30 years ago, and discovered by me and my peers in the late 1990’s. We talked about this book a lot, as it described a (business) world where we didn’t want to work in. We wanted to do better. In a way, this book was a spark to found our own company and don’t repeat the mistakes that seemed to be prevalent in our industry. If you’ve ever shaken your head about “the management”, do yourself a favor and read this book. It will pinpoint the precise problem you’ve felt and give you the words to describe it. And if you’ve read “Peopleware”, liked it and want more, there is good news: There is a whole series waiting for you (not just Vienna).

Epilogue to Part I

These are the first five books from my list, with the last entry being more of a catch-all for a whole series. Remember that this isn’t a generic “go and read these books if you want to call yourself a professional software developer” list. I’m not gatekeeping and it would be useless to even try to do so. These books helped me further my career in the last 20 years, they won’t necessarily help you for the next 20 years. Good books are published every year, you just have to read them.

I’m looking forward to share the second part of my list in the next blog post of this series. Stay tuned!


A mindset for inherited source code

One field of expertise our company provides is the continuation of existing software projects. While this sounds very easy to accomplish, in reality, there are a few prerequisites that a software project has to provide to be continuable. The most important one is the source code of the system, obviously. If the source code is accessible (this is a problem more often than you might think!), the biggest hurdle is now the mindset and initial approach of the developers that inherit it.

The mindset

Most developers have a healthy “greenfield” project mindset. There is a list of requirements, so start coding and fulfill them. If the code obstructs the way to your goal, you reshape it in a meaningful manner. The more experience you have with developing software, the better the resulting design and architecture of the code will be. Whether you apply automatic tests to your software (and when) is entirely your decision. In short: You are the master of the code and forge it after your vision. This is a great mindset for projects in the early phases of development. But it will actively hinder you in later phases of your project or in case you inherit foreign code.

For your own late-phase projects and source code written by another team, another mindset provides more value. The “brownfield” metaphor doesn’t describe the mindset exactly. I have three metaphors that describe parts of it for me: You’ll need to be an archeologist, a forensicist (as in “securer of criminal evidence”) and a minefield clearer. If you hear the word archeologist, don’t think of Indiana Jones, but of somebody sitting in the scorching desert, clearing a whole football field from sand with only a shaving brush and his breath. If you think about being a forensicist, don’t think of your typical hero criminalist who rearranges the photos of the crime scene to reveal a hidden hint, but the guy in a white overall who has to take all the photos without disturbing the surrounding (and being disturbed by it). If you think about the minefield clearer: Yes, you are spot on. He has to rely on his work and shouldn’t move too fast in any direction.

The initial approach

This sets the scene for your initial journey inside foreign source code: Don’t touch anything or at least be extra careful, only dust it off in the slightest possible manner. Watch where you step in and don’t get lost. Take a snapshot, mental or written, of anything suspicious you’ll encounter. There will be plenty of temptation to lose focus and instantly improve the code. Don’t fall for it. Remember the forensicist: what would the detective in charge of this case say if you “improved the scenery a bit” to get better photos? This process reminds me so much of a common approach to the game “Minesweeper” that I included the minefield clearer in the analogy. You start somewhere on the field and mark every mine you indirectly identify without ever really revealing them.

Most likely, you don’t find any tests or an issue tracker where you can learn about the development history. With some luck, you’ll have a commit history with meaningful comments. Use the blame view as often as you can. This is your archeological skills at work: Separating layers and layers of code all mingled in one place. A good SCM system can clear up a total mess for you and reveal the author’s intent for it. Without tests, issues and versioning, you cannot distinguish between a problem and a solution, accidental and deliberate complexity or a bug and a feature. Everything could mean something and even be crucial for the whole system or just be useless excess code (so-called “live weight” because the code will be executed, but with no effect in terms of features). To name an example, if you encounter a strange sleep() call (or multiple calls in a row), don’t eliminate or change them! The original author probably “fixed” a nasty bug with it that will come back sooner than you know it.

Walking on broken glass

And this is what you should do: Leave everything in its place, broken, awkward and clumsy, and try to separate your code from “their” code as much as possible. The rationale is to be able to differentiate between “their” mess and “your” mess and make progress on your part without breaking the already existing features. If you cannot wait any longer to clean up some of the existing code, make sure to release into production often and in a timely manner, so you still know what changed if something goes wrong. If possible, try to release two different kinds of new versions:

  • One kind of new version only incorporates refactorings to the existing code. If anything goes wrong or seems suspicious, you can easily bail out and revert to the previous version without losing functionality.
  • The other kind only contains new features, added with as little change to existing code as possible. Hopefully, this release will not break existing behaviour. If it does, you should double-check your assumptions about the code. If reasonably achievable, do not assume anything or at least write an automatic test to validate your assumption.

Personally, I call this approach the “tick-tock” release cycle, modelled after the release cycle of Intel for its CPUs.

Changing gears

A very important aspect of software development is to know when to “change gears” and switch from greenfield to brownfield or from development to maintainance mode. The text above describes the approach with inherited code, where the gear change is externally triggered by transferring the source code to a new team. But in reality, you need to apply most of the practices on your own source code, too. As soon as your system is in “production”, used in the wild and being filled with precious user data, it changes into maintainance mode. You cannot change existing aspects as easily as before.
In his book “Implementation Patterns” (2008), Kent Beck describes the development of frameworks among other topics. One statement is:

While in conventional development reducing complexity to a minimum is a valuable strategy for making the code easy to understand, in framework development it is often more cost-effective to add complexity in order to enhance the framework developer’s ability to improve the framework without breaking client code.
(Chapter 10, page 118)

I not only agree with this statement but think that it partly applies to “conventional development” in maintainance mode, too. Sometimes, the code needs additional complexity to cope with existing structures and data. This is the moment when you’ve inherited your own code.