Principles of Package Design
Principles of Package Design
Preparing your code for reuse
About the Book
In Principles of Package Design Matthias Noback tells you everything about designing software components, also known as packages. In the first part you'll revisit the SOLID principles of class design. They will help you prepare your classes for use in packages. The second part covers the important, yet lesser known package design principles. When you've finished this book, you'll be ready to design packages that have high cohesion, low coupling and are at the same time user- and maintainer-friendly.
This book has been revised and then republished by Apress. From now on you can order it from them: https://www.apress.com/us/book/9781484241189
About the Author
Table of Contents
-
Introduction
- The situation
- Overview of the contents
- Notes about the code samples
- Thank you
-
Class design
-
Introduction
- SOLID principles
- Why follow the principles?
- Prepare for change
-
The Single responsibility principle
- A class with too many responsibilities
- Responsibilities are reasons to change
- Refactoring: using collaborator classes
- Advantages of having a single responsibility
- A small peek ahead: common closure
-
The Open/closed principle
- A class that is closed for extension
- Refactoring: abstract factory
- Refactoring: making the abstract factory open for extension
- Refactoring: polymorphism
-
Conclusion
- Packages need classes that are open for extension
-
The Liskov substitution principle
- Violation: a derived class does not have an implementation for all methods
- Violation: different substitutes return things of different types
- Violation: a derived class is less permissive with regard to method arguments
- Violation: secretly programming a more specific type
- Conclusion
-
The Interface segregation principle
-
Violation: leaky abstractions
-
Refactoring: create separate interfaces and use multiple inheritance
- What did we do?
-
Refactoring: create separate interfaces and use multiple inheritance
-
Violation: multiple use cases
- Refactoring: separate interfaces and multiple inheritance
-
Violation: no interface, just a class
- Implicit changes in the implicit interface
- Refactoring: add header and role interfaces
-
Violation: leaky abstractions
-
The Dependency inversion principle
-
Example of dependency inversion: the FizzBuzz generator
-
Making the
FizzBuzzclass open for extension -
Removing the specificness from the
FizzBuzzclass
-
Making the
-
Violation: a high-level class depends upon a low-level class
- Refactoring: abstractions and concretions both depend on abstractions
-
Violation: a class depends upon a class from another package
- Solution: add an abstraction and remove the dependency using composition
-
Conclusion
- Peeking ahead: abstract dependencies
-
Example of dependency inversion: the FizzBuzz generator
-
Introduction
-
Package design
-
Principles of cohesion
-
- Becoming a programmer
- The hardest part
-
Cohesion
- Class design principles benefit cohesion
- Package design principles, part I: Cohesion
-
-
The Release/reuse equivalence principle
- Keep your package under version control
- Add a package definition file
-
Use semantic versioning
-
Design for backward compatibility
-
Rules of thumb
- Don’t throw anything away
- When you rename something, add a proxy
- Only add parameters at the end and with a default value
- Methods should not have side effects
- Dependency versions should be permissive
- Use objects instead of primitive values
- Use private object properties and methods for information hiding
- Use object factories
- And so on
-
Rules of thumb
-
Design for backward compatibility
-
Add meta files
-
READMEand documentation- Installation and configuration
- Usage
- Extension points
- Limitations (optional)
- License
- Change log
-
-
Quality control
- Quality from the user’s point of view
-
What the package maintainer needs to do
- Add tests
- Conclusion
-
The Common reuse principle
-
Signs that the principle is being violated
-
Feature strata
- Obvious stratification
- Obfuscated stratification
-
Classes that can only be used when … is installed
- Suggested refactoring
- A package should be “linkable”
- Cleaner releases
-
Bonus features
- Suggested refactoring
- Sub-packages
-
Feature strata
-
Conclusion
- Guiding questions
- When to apply the principle
- When to violate the principle
- Why not to violate the principle
-
Signs that the principle is being violated
-
The Common closure principle
-
A change in one of the dependencies
- Assetic
-
A change in an application layer
- FOSUserBundle
-
A change in the business
- Sylius
- The tension triangle of cohesion principles
-
A change in one of the dependencies
-
Principles of coupling
- Coupling
-
The Acyclic dependencies principle
-
Coupling: discovering dependencies
-
Different ways of package coupling
- Composition
- Inheritance
- Implementation
- Usage
- Creation
- Functions
- Not to be considered: global state
- Visualizing dependencies
-
Different ways of package coupling
-
The Acyclic dependencies principle
- Nasty cycles
-
Cycles in a package dependency graph
- Dependency resolution
- Release management
- Is it all that bad?
-
Solutions for breaking the cycles
- Some pseudo-cycles and their dissolution
-
Some real cycles and their dissolution
- Dependency inversion
-
Inversion of control
- Mediator
- Chain of responsibility
- Mediator and chain of responsibility combined: an event system
- Conclusion
-
Coupling: discovering dependencies
-
The Stable dependencies principle
- Stability
- Not every package can be highly stable
- Unstable packages should only depend on more stable packages
- Measuring stability
- Decreasing instability, increasing stability
-
Violation: your stable package depends on a third-party unstable package
- Solution: use dependency inversion
- A package can be both responsible and irresponsible
- Conclusion
-
The Stable abstractions principle
- Stability and abstractness
-
How to determine if a package is abstract
-
The
Ametric
-
The
- Abstract things belong in stable packages
- Abstractness increases with stability
- The main sequence
-
Types of packages
- Concrete, instable packages
- Abstract, stable packages
- Strange packages
- Conclusion
-
Conclusion
-
Creating packages is hard
- Reuse-in-the-small
- Reuse-in-the-large
- Embracing software diversity
- Component reuse is possible, but requires more work
-
Creating packages is doable
- Reducing the impact of the first rule of three
- Reducing the impact of the second rule of three
- Creating packages is easy?
-
Creating packages is hard
-
Principles of cohesion
-
Appendices
-
Appendix I: The full
Pageclass
-
Appendix I: The full
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$12,124,424writing, 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) and EPUB (for phones, tablets and 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
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 most complete guide around introducing the reader to this exciting MCU portfolio from ST Microelectronics and its official CubeHAL and STM32CubeIDE development environment.
- #2
Functional Programming Made Easier
Charles ScalfaniA Functional Programming book from beginner to advanced without skipping a single step along the way.
In my 40 years of programming, I've felt that programming books always let me down, especially Functional Programming books. So, I wrote the book I wish I had 5 years ago.
Functional Programming will never be easy, but it can be easier.
- #3
Jetpack Compose internals
Jorge CastilloJetpack Compose is the future of Android UI. Master how it works internally and become a more efficient developer with it. You'll also find it valuable if you are not an Android dev. This book provides all the details to understand how the Compose compiler & runtime work, and how to create a client library using them.
- #4
R Programming for Data Science
Roger D. PengThis book brings the fundamentals of R programming to you, using the same material developed as part of the industry-leading Johns Hopkins Data Science Specialization. The skills taught in this book will lay the foundation for you to begin your journey learning data science. Printed copies of this book are available through Lulu.
- #5
Windows 11 Field Guide
Rafael Rivera and Paul ThurrottThe Windows 11 Field Guide is a full-length e-book about the latest version of Microsoft Windows, aimed at those users who will upgrade from Windows 10 or acquire Windows 11 with a new PC.
- #6
node-opcua by example
Etienne RossignonGet the best out of node-opcua through a set of documented examples by the author himself that will allow you to create stunning OPCUA Servers or Clients.
- #7
C++20 - The Complete Guide
Nicolai M. JosuttisAll new language and library features of C++20 (for those who know previous C++ versions).
The book presents all new language and library features of C++20. Learn how this impacts day-to-day programming, to benefit in practice, to combine new features, and to avoid all new traps.
Buy early, pay less, free updates.
Other books:
- #8
Introducing EventStorming
Alberto BrandoliniThe deepest tutorial and explanation about EventStorming, straight from the inventor.
- #9
Node-OPCUA by example - edition 2022
Etienne RossignonGet the best out of node-opcua through a set of documented examples by the author himself that will allow you to create stunning OPCUA Servers or Clients.
- #10
Functional Event-Driven Architecture
Gabriel VolpeExplore the event-driven architecture (EDA) in a purely functional way. Learn to design and develop distributed systems that scale. Identify common design patterns in such systems.
Take your functional programming skills to the next level by joining me in developing a distributed system powered by Apache Pulsar and Fs2 streams, all in Scala 3!
Top Bundles
- #1
1500 QUIZ COMMENTATI (3 libri)
3 Books
Tre libri dei QUIZ MMG Commentati al prezzo di DUE! I QUIZ dei concorsi ufficiali di Medicina Generale relativi agli anni: 2000-2001-2003-2012-2013-2014-2015-2016-2017-2018-2019-2020-2021 +100 inediti Raccolti in unico bundle per aiutarvi nello studio e nella preparazione al concorso. All'interno di ogni libro i quiz sono stati suddivisi per... - #2
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... - #3
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... - #4
Software Architecture
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... - #6
The Python Craftsman
3 Books
The Python Craftsman series comprises The Python Apprentice, The Python Journeyman, and The Python Master. The first book is primarily suitable for programmers with some experience of programming in another language. If you don't have any experience with programming this book may be a bit daunting. You'll be learning not just a programming... - #10
Statistics - All Lee Baker's Books
10 Books
This bundle includes all of the statistics books that Lee Baker has published at LeanPub 13 Statistics Books*1 PlaceNo Hassle! All in both epub and mobi formats - perfect for all devices and screen sizes. --------------------------------------------------------- *The book listed as Getting Started With Statistics is a bundle of 4 books...
