The Legacy Code Programmer's Toolbox
The Legacy Code Programmer's Toolbox
Practical skills for software professionals working with legacy code
About the Book
The Legacy Code Programmer's Toolbox is a guide for professionals that have to work with legacy code.
Working with legacy code is challenging. However legacy code is everywhere, and this is what many developers have to work with to create value.
This book will show you how to deal with legacy code efficiently and with a positive approach: how to be in a motivated mindset, how to understand the code, reduce the size of long functions, and how you can even turn legacy code to your advantage to learn how to improve your programming skills.
You'll see the power of knowledge to be effective with legacy code as well as how to have you and every member of your team acquire this precious knowledge.It will teach you efficient ways to work as an individual as well as how to collaborate with your teammates to work effectively with legacy code.
Finally, this book will show you how you can skip to the places of the codebase where you can create the most value. You will learn how to find the source of a bug quickly in a codebase even if you don't know a lot of it, and where to target your refactoring efforts so that they make a difference.
About the Author
Bundles that include this book
Reader Testimonials
Kate Gregory
"The material will leave you ready to take on whatever legacy code you encounter"
This is a warm and reassuring book that will equip you to read, understand, and update legacy code in any language. The advice is immediately actionable, and you can start to use it right after reading the chapters. The experience of the author is clearly hard-won; he generously shares it to save you a lot of trouble. The material will leave you ready to take on whatever legacy code you encounter, with a smile on your face. I happily endorse it.
Bartłomiej Filipek
"Tools to make your daily job much fun and rewarding"
Let's face it - legacy code is everywhere! We can complain or... make it our friend. And this is exactly what Jonathan is offering is his book. With a vivid language, lots of examples and use cases the text will shift your attitude towards legacy code. You'll be equipped with a lot of tools to make your daily job much fun and rewarding.
Arne Mertz
"A great read for everyone"
The Legacy Code Programmer's Toolbox gives actionable advice about how to deal with the sometimes harsh reality of our work. You'll learn how to understand and when to refactor legacy code, and what attitude keeps you sane and productive when facing legacy code. This book is a great read for everyone: Junior developers wondering what is coming for them and how to face it, and seniors still wondering what could have been done differently when that old project came to a screeching halt.
Rainer Grimm
"A unique book about our day to day life as a professional software developer"
Wow! I read the book in one day. For two reasons. First, it is quite entertaining. Second, it is even more enlightening. Jonathan Boccara wrote a unique book about our day to day life as a professional software developer: Working with legacy code. He shows with many examples, how we should approach, understand, and improve legacy code if necessary. You should read it, because Jonathan's book will give you new, critical insight.
Victor Ciura
"My top recommendation on the subject"
As I read Jonathan's book I found a lot of comfort knowing that it will be a lot easier for many developers coping with understanding & working with legacy code. The book helps you get in the right mindset to deal with legacy code and explores various techniques and tools to help you along the way, with lots of carefully crafted code examples. I enjoyed this book a lot and learned some handy tricks along the way. "Jonathan's toolbox" just became my top recommendation on this subject.
Kris van Rens
"A must-read"
I loved it. It's great material, right up there with classics such as Micheal Feathers' "Working Effectively with Legacy Code". Everyone has to deal with legacy code, often reluctantly so. The mental attitude this book conveys is of great importance. Now, I'm better able to pinpoint and solve mental issues as a lead developer/team lead, and that's brilliant. I'm definitely going to recommend this to all my developer colleagues/friends, regardless of their background -- this is a must read!
Table of Contents
-
- Foreword
- Acknowledgments
-
Introduction: There is a lot of legacy, out there
- Legacy code
- You didn’t become a developer for this
- There is a lot of legacy, out there
-
Part I: Approaching legacy code
-
Chapter 1: The right attitude to deal with legacy code
- The natural reaction: who the f*** wrote this
- A humble view of legacy code
- The efficient approach: taking ownership
- Having a role model
-
Chapter 2: How to use bad code to learn how to write great code
- Don’t like the code? Elaborate, please.
- The vaccine against bad code is bad code
- Be aware of what good code looks like
-
Chapter 3: Why reading good code is important (and where to find it)
- The importance of reading good code
- Where to find good code
- Become more efficient with legacy code
-
Chapter 1: The right attitude to deal with legacy code
-
Part II: 10 techniques to understand legacy code
-
Chapter 4: 3 techniques to get an overview of the code
- 1) Choosing a stronghold
- 2) Starting from the inputs and outputs of the program (and how to find them)
- 3) Analysing well-chosen stacks
-
Chapter 5: 4 techniques to become a code speed-reader
- 1) Working your way backwards from the function’s outputs
- 2) Identifying the terms that occur frequently
- 3) Filtering on control flow
- 4) Distinguishing the main action of the function
-
Chapter 6: 3 techniques to understand code in detail
- 1) Using “practice” functions to improve your code-reading skills
- 2) Decoupling the code
- 3) Teaming up with other people
- It gets easier with practice
-
Chapter 4: 3 techniques to get an overview of the code
-
Part III: Knowledge
-
Chapter 7: Knowledge is Power
- Where did the knowledge go?
-
Chapter 8: How to make knowledge flow in your team
- Writing precious documentation
- Telling your tales: acquiring knowledge in Eager mode
- Knowing who to ask: getting knowledge in Lazy mode
- Pair-programming and mob-programming
- External sources of knowledge
- Make the knowledge flow
-
Chapter 9: The Dailies: knowledge injected in regular doses
- What are Dailies?
- Monthly sessions
- The major benefits of Dailies
- There is plenty of content out there
- Be the one who spreads knowledge
-
Chapter 7: Knowledge is Power
-
Part IV: Cutting through legacy code
-
Chapter 10: How to find the source of a bug without knowing a lot of code
- The slowest way to find the source of a bug
- The quickest way to find the source of a bug
- A binary search for the root cause of a bug
- A case study
-
Chapter 11: The Harmonica School: A case study in diagnosing a bug quickly in an unfamiliar code base
- Lesson subscriptions
- Let’s find the source of that bug, quickly
- The more time you spend in the application, the less total time you spend debugging
-
Chapter 12: What to fix and what not to fix in a legacy codebase
- Legacy code is a bully
- The value-based approach (a.k.a. “Hit it where it hurts”)
- Where does it hurt?
- Use the value-based approach
-
Chapter 13: 5 refactoring techniques to make long functions shorter
- The birth of a Behemoth
- Identifying units of behaviour
-
1) Extract
forloops - 2) Extract intensive uses of the same object
-
3) Raise the level of abstraction in unbalanced
ifstatements - 4) Lump up pieces of data that stick together
- 5) Follow the hints in the layout of the code
- 6) Bonus: using your IDE to hide code
- The impact on performance
-
Conclusion: The legacy of tomorrow
- The bigger picture of writing code
- How to deal with legacy code
- But you’re also person A
- Parting words
- References
-
Chapter 10: How to find the source of a bug without knowing a lot of code
- Notes
The Leanpub 60-day 100% Happiness Guarantee
Within 60 days of purchase you can get a 100% refund on any Leanpub purchase, in two clicks.
See full terms
Do Well. Do Good.
Authors have earned$11,574,417writing, publishing and selling on Leanpub, earning 80% royalties while saving up to 25 million pounds of CO2 and up to 46,000 trees.
Learn more about writing on Leanpub
Free Updates. DRM Free.
If you buy a Leanpub book, you get free updates for as long as the author updates the book! Many authors use Leanpub to publish their books in-progress, while they are writing them. All readers get free updates, regardless of when they bought the book or how much they paid (including free).
Most Leanpub books are available in PDF (for computers), EPUB (for phones and tablets) and MOBI (for Kindle). The formats that a book includes are shown at the top right corner of this page.
Finally, Leanpub books don't have any DRM copy-protection nonsense, so you can easily read them on any supported device.
Learn more about Leanpub's ebook formats and where to read them
Top Books
- #1
Recipes for Decoupling
Matthias Noback - #2
The BDD Books - Discovery (Japanese Edition)
Gáspár Nagy, Seb Rose, and Yuya Kazamaウクライナ難民を支援 - 2022年5月末まで延長！
この本の売り上げの50％は、 https://unicef.hu/veszhelyzet-ukrajnaban と https://int.depaulcharity.org/fundraising-for-depaul-ukraine/ に寄付されます。
本書籍は、振る舞い駆動開発(Behavior Driven Development, BDD)や受け入れテスト駆動開発(Acceptance Test-Driven Development, ATDD)の発見フェーズを最大限に活用する方法を提供します。
- #3
SignalR on .NET 6 - the Complete Guide
Fiodar SazanavetsLearn everything there is to learn about SignalR and how to integrate it with the latest .NET 6 and C# 10 features. Learn how to connect any type of client to SignalR, including plain WebSocket client. Learn how to build interactive applications that can communicate with each other in real time without making excessive calls.
- #4
Agile Testing Condensed Japanese Edition
Yuya Kazama, Janet Gregory, and Lisa CrispinJanet GregoryとLisa Crispinによる2019年9月発行の書籍『Agile Testing Condensed』の日本語翻訳版です。アジャイルにおいてどのような考えでテストを行うべきなのか簡潔に書かれています！
- #5
OpenIntro Statistics
David Diez, Christopher Barr, Mine Cetinkaya-Rundel, and OpenIntroA complete foundation for Statistics, also serving as a foundation for Data Science.
Leanpub revenue supports OpenIntro (US-based nonprofit) so we can provide free desk copies to teachers interested in using OpenIntro Statistics in the classroom and expand the project to support free textbooks in other subjects.
More resources: openintro.org.
- #6
The easiest way to learn design patterns
Fiodar SazanavetsLearn design patterns in the easiest way possible. You will no longer have to brute-force your way through each one of them while trying to figure out how it works. The book provides a unique methodology that will make your understanding of design patterns stick. It can also be used as a reference book where you can find design patterns in seconds.
- #7
Functional event-driven architecture: Powered by Scala 3
Gabriel VolpeExplore the event-driven architecture (EDA) in a purely functional way, mainly powered by Fs2 streams in Scala 3!
Leverage your functional programming skills by designing and writing stateless microservices that scale, powered by stateful message brokers.
- #8
Tech Giants in Healthcare
Dr. Bertalan MeskoThis comprehensive guide, Tech Giants in Healthcare, clarifies how and why big tech companies step into healthcare, and breaks it down from one market player to the other in what direction they are going, what tools they are using and what horizons they have in front of them.
- #9
CCIE Service Provider Version 4 Written and Lab Exam Comprehensive Guide
Nicholas RussoThe service provider landscape has changed rapidly over the past several years. Networking vendors are continuing to propose new standards, techniques, and procedures for overcoming new challenges while concurrently reducing costs and delivering new services. Cisco has recently updated the CCIE Service Provider track to reflect these changes; this book represents the author's personal journey in achieving that certification.
- #10
Mastering STM32 - Second Edition
Carmine NovielloWith more than 1200 microcontrollers, STM32 is probably the most complete ARM Cortex-M platform on the market. This book aims to be the first guide around that introduces the reader to this exciting MCU portfolio from ST Microelectronics and its official CubeHAL and STM32CubeIDE development environment.
Top Bundles
- #1
Practical FP in Scala + Functional event-driven architecture
2 Books
Practical FP in Scala (A hands-on approach) & Functional event-driven architecture, aka FEDA, (Powered by Scala 3), together as a bundle! The content of PFP in Scala is a requirement to understand FEDA so why not take advantage of this bundle!? - #2
All the Books of The Medical Futurist
6 Books
We put together the most popular books from The Medical Futurist to provide a clear picture about the major trends shaping the future of medicine and healthcare. Digital health technologies, artificial intelligence, the future of 20 medical specialties, big pharma, data privacy, digital health investments and how technology giants such as Amazon... - #3
Software Architecture for Developers: Volumes 1 & 2 - Technical leadership and communication
2 Books
"Software Architecture for Developers" is a practical and pragmatic guide to modern, lightweight software architecture, specifically aimed at developers. You'll learn:The essence of software architecture.Why the software architecture role should include coding, coaching and collaboration.The things that you really need to think about before... - #4
CCIE Service Provider Ultimate Study Bundle
2 Books
Piotr Jablonski, Lukasz Bromirski, and Nick Russo have joined forces to deliver the only CCIE Service Provider training resource you'll ever need. This bundle contains a detailed and challenging collection of workbook labs, plus an extensively detailed technical reference guide. All of us have earned the CCIE Service Provider certification... - #6
Pattern-Oriented Memory Forensics and Malware Detection
2 Books
This training bundle for security engineers and researchers, malware and memory forensics analysts includes two accelerated training courses for Windows memory dump analysis using WinDbg. It is also useful for technical support and escalation engineers who analyze memory dumps from complex software environments and need to check for possible...
