Source code for the book Data Oriented Programming in Java (by me! Chris Kiehl!)
- Get the book here!
- ISBN: 9781633436930
Note
This book is in Early Access while I continue to work on it. This repository will be updated as new chapters are released.
This book is a distillation of everything I’ve learned about what effective development looks like in Java (so far!). It’s what’s left over after years of experimenting, getting things wrong (often catastrophically), and slowly having anything resembling “devotion to a single paradigm” beat out of me by the great humbling filter that is reality.
Data-orientation doesn't replace object orientation. The two work together and enhance each other. DoP is born from a very simple idea, and one that people have been repeatedly rediscovering since the dawn of computing: “representation is the essence of programming”. Programs that are organized around the data they manage tend to be simpler, smaller, and significantly easier understand. When we do a really good job of capturing the data in our domain, the rest of the system tends to fall into place in a way which can feel like it’s writing itself.
To download a copy of this repository, click on the Download ZIP button or execute the following command in your terminal:
git clone https://github.com/chriskiehl/Data-Oriented-Programming-In-Java-Book.git
(If you downloaded the code bundle from the Manning website, please consider visiting the official code repository on GitHub at https://github.com/chriskiehl/Data-Oriented-Programming-In-Java-Book for the latest updates.)
The project is built with Gradle.
gradle build
The tests/ package houses all of the runnable code. You can run all the tests in a class with this command:
gradle test --tests 'path.to.test.Class'
e.g.
gradle test --tests 'dop.chapter02.Listings'
You can also run individual tests by specifying the method.
gradle test --tests 'dop.chapter02.Listings.listing_2_1'
Each chapter in the book has an associated package in the src/test/ directory. Most of the examples aren't necessarily things that we'll run. They're primarily for study. We'll look at them and go "Hmm. Interesting." DoP is a book that's about design decisions and how they affect our code. We're striving to make incorrect states impossible to express or compile. Thus, a lot of the examples are exploring how code changes (or disappears entirely) when we get our modeling right.
Listings in the Book vs Code
Each listing in the book will have a corresponding example in the code. The Javadoc will describe which listing the code applies to.
/**
* ───────────────────────────────────────────────────────
* Listing 1.1
* ───────────────────────────────────────────────────────
*
* Here's an example of how we might traditionally model
* data "as data" using a Java object.
* ───────────────────────────────────────────────────────
*/
Sometimes, separate listings in the book will be combined into one example in the code.
/**
* ───────────────────────────────────────────────────────
* Listings 1.5 through 1.9
* ───────────────────────────────────────────────────────
* Representation affects our ability to understand the code
* as a whole. [...]
* ───────────────────────────────────────────────────────
*/
Note
The class names in the code will often differ from the class names used in the book. Java doesn't let us redefine classes over and over again (which we do in the book as we refactor), so we 'cheat' by appending a qualifying suffix. For instance, ScheduledTask in listing A might become ScheduledTaskV2 or ScheduledTaskWithBetterOOP in a subsequent example code. The listing numbers in the Javadoc will always tie to the Listing numbers in the book.
Character Encodings
Make sure your IDE / Text editor is configured for UTF-8 character encoding (Windows tends to default to other encodings). Many of the in-code diagrams leverage the utf-8 charset.
Example utf-8 diagram:
// An informational black hole!
//
// ┌──────── It returns nothing!
// ▼
// void reschedule( ) { // ◄─────────────────────────────────┐
// ... ▲ │ Compare how very different
// } └────── It takes nothing! │ these two methods are in
// │ terms of what they convey
RetryDecision reschedule(FailedTask failedTask) { // ◄───┘ to us as readers
// ...
}
| Chapter | Code Listings |
|---|---|
| Chapter 01 - Data Oriented Programming | Listings.java |
| Chapter 02 - Data, Identity, and Values | Listings.java |
| Chapter 03 - Data and Meaning | Listings.java |
| Chapter 04 - Representation is the Essence of Programming | Listings.java |
| Chapter 05 - Coming soon! | Coming soon! |
I'd love to hear any and all feedback. You can leave comments in the Manning forum. I'm also very responsive to emails. If you have a question about the repo, feel free to write me at me@chriskiehl.com.