book

Object Design Style Guide

Name: Object Design Style Guide
Author: Matthias Noback
ISBN: 9781617296857

by Matthias Noback

January 2020

Intermediate to advanced

288 pages

6h 45m

English

Manning Publications

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Copyright
Dedication
Brief Table of Contents
Table of Contents
Foreword
Preface
Acknowledgments
About this Book
Who should read this bookHow this book is organized: A roadmapAbout the codeliveBook discussion forum
About the Author
About the Cover Illustration

Chapter 1. Programming with objects: A primer
1.1. Classes and objects1.2. State1.3. Behavior1.4. Dependencies1.5. Inheritance1.6. Polymorphism1.7. Composition1.8. Class organization1.9. Return statements and exceptions1.10. Unit testing1.11. Dynamic arraysSummary
Chapter 2. Creating services
2.1. Two types of objects2.2. Inject dependencies and configuration values as constructor arguments2.3. Inject what you need, not where you can get it from2.4. All constructor arguments should be required2.5. Only use constructor injection2.6. There’s no such thing as an optional dependency2.7. Make all dependencies explicit2.8. Task-relevant data should be passed as method arguments instead o- of constructor arguments2.9. Don’t allow the behavior of a service to change after it has been instantiated2.10. Do nothing inside a constructor, only assign properties2.11. Throw an exception when an argument is invalid2.12. Define services as an immutable object graph with only a few entry pointsSummaryAnswers to the exercises
Chapter 3. Creating other objects
3.1. Require the minimum amount of data needed 3.1 to behave consistently3.2. Require data that is meaningful3.3. Don’t use custom exception classes for invalid argument exceptions3.4. Test for specific invalid argument exceptions by analyzing the ex- xception’s message3.5. Extract new objects to prevent domain invariants from being verif- fied in multiple places3.6. Extract new objects to represent composite values3.7. Use assertions to validate constructor arguments3.8. Don’t inject dependencies; optionally pass them as method arguments3.9. Use named constructors3.10. Don’t use property fillers3.11. Don’t put anything more into an object than it needs3.12. Don’t test constructors3.13. The exception to the rule: Data transfer objectsSummaryAnswers to the exercises
Chapter 4. Manipulating objects
4.1. Entities: Identifiable objects that track changes and record events4.2. Value objects: Replaceable, anonymous, and immutable values4.3. Data transfer objects: Simple objects with fewer design rules4.4. Prefer immutable objects4.5. A modifier on an immutable object should return a modified copy4.6. On a mutable object, modifier methods should be command methods4.7. On an immutable object, modifier methods should have declarative names4.8. Compare whole objects4.9. When comparing immutable objects, assert equality, not sameness4.10. Calling a modifier method should always result in a valid object4.11. A modifier method should verify that the requested state change is valid4.12. Use internally recorded events to verify changes on mutable objects4.13. Don’t implement fluent interfaces on mutable objectsSummaryAnswers to the exercises
Chapter 5. Using objects
5.1. A template for implementing methods5.2. Some rules for exceptionsSummaryAnswers to the exercises
Chapter 6. Retrieving information
6.1. Use query methods for information retrieval6.2. Query methods should have single-type return values6.3. Avoid query methods that expose internal state6.4. Define specific methods and return types for the queries you want to make6.5. Define an abstraction for queries that cross system boundaries6.6. Use stubs for test doubles with query methods6.7. Query methods should use other query methods, not command methodsSummaryAnswers to the exercises
Chapter 7. Performing tasks
7.1. Use command methods with a name in the imperative form7.2. Limit the scope of a command method, and use events to perform secondary tasks7.3. Make services immutable from the outside as well as on the inside7.4. When something goes wrong, throw an exception7.5. Use queries to collect information and commands to take the next steps7.6. Define abstractions for commands that cross system boundaries7.7. Only verify calls to command methods with a mockSummaryAnswers to the exercises
Chapter 8. Dividing responsibilities
8.1. Separate write models from read models8.2. Create read models that are specific for their use cases8.3. Create read models directly from their data source8.4. Build read models from domain eventsSummaryAnswers to the exercises
Chapter 9. Changing the behavior of services
9.1. Introduce constructor arguments to make behavior configurable9.2. Introduce constructor arguments to make behavior replaceable9.3. Compose abstractions to achieve more complicated behavior9.4. Decorate existing behavior9.5. Use notification objects or event listeners for additional behavior9.6. Don’t use inheritance to change an object’s behavior9.7. Mark classes as final by default9.8. Mark methods and properties private by defaultSummaryAnswers to the exercises
Chapter 10. A field guide to objects
10.1. Controllers10.2. Application services10.3. Write model repositories10.4. Entities10.5. Value objects10.6. Event listeners10.7. Read models and read model repositories10.8. Abstractions, concretions, layers, and dependenciesSummary
Chapter 11. Epilogue
11.1. Architectural patterns11.2. Testing11.3. Domain-driven design11.4. Conclusion
Appendix: Coding standard for the code samples
Style guide cheat sheet
Index
List of Figures
List of Tables
List of Listings

Overview

Objects are the central concept of languages like Java, Python, C#. Applying best practices for object design means that your code will be easy to read, write, and maintain. Object Design Style Guide captures dozens of techniques for creating pro-quality OO code that can stand the test of time. Examples are in an instantly familiar pseudocode, teaching techniques you can apply to any OO language, from C++ to PHP.

About the Technology
Well-written OO code is a pleasure to read, modify, and debug. Elevate your coding style by mastering the universal best practices for object design presented in this book. These clearly presented rules, which apply to any OO language, maximize the clarity and durability of your codebase and increase productivity for you and your team.

About the Book
Object Design Style Guide presents dozens of professional techniques for writing OO code. In it, veteran developer Matthias Noback lays out design rules for constructing objects, defining methods, changing and exposing state, and much more. All examples use instantly familiar pseudocode, so you can follow along in the language you prefer. You’ll go case by case as you explore important scenarios and challenges for object design and then walk through a simple web application that demonstrates how different types of objects can work together effectively.

What's Inside

Universal design rules for a wide range of objects
Best practices for testing objects
A catalog of common object types
Exercises for each chapter to test your object design skills

About the Reader
For readers familiar with an object-oriented language and basic application architecture.

About the Author
Matthias Noback is a professional web developer with nearly two decades of experience. He runs his own web development, training, and consultancy company called “Noback’s Office.”

Quotes
Offers both guidelines and guidance on how to achieve a clear, consistent tone across a larger team.
- From the Foreword by Ross Tuck

Demystifies OOP and describes how to use it to design truly secure and performant applications.
- Charles Soetan, Plum.io

Extremely well-written content for all skill levels in the industry.
- Shayn Cornwell, XeroOne Systems

An objective go-to reference for programmers wanting to standardize their OOP procedures.
- Joseph T. Lyons, SYSCON International

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