In the last chapter, we went over the core of what design patterns are, the common problems they solve, and how we’ll go about learning and implementing each of them throughout our adventure. In this chapter, we’ll start our practical journey by exploring the Singleton pattern, which helps when you want a single instance of a class to be globally accessible. For applications and games, you’ll commonly see this type of functionality with manager or service classes that keep track of global state or provide access to system-wide utilities. However, we need to be aware of potential risks with global state (and how to protect our newly accessible data), which we’ll discuss later in the chapter.

Anytime you bring up the Singleton pattern in programming circles, you’re likely to hear an audible sigh, some hushed booing, and maybe even an angry shout or two. And that’s precisely why I like to teach this...

Updating a MonoBehavior into a persistent singleton

Imagine you are building a platforming game where the player collects items through multiple levels. Your team lead asks you to create a manager script to track the player’s score, handle scene transitions, and ensure there’s always one unique instance in a scene. Our first task is to ensure that the game manager class in the starter project only ever has one active instance.

Open Manager.cs and update the code to match the following code, which sets the singleton instance or destroys the GameObject that the script is attached to if an instance already exists:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;
using UnityEngine.SceneManagement;
public class Manager : MonoBehaviour
{
    // 1
    public static Manager Instance;    
    public int score = 0;
    public int startingLevel = 1;
    // 2
    void Awake()    
    {
        // 3
        if(Instance...

Creating singletons as ScriptableObjects

Imagine you and your design team need to create, configure, and test singleton classes in the Unity Editor. Using ScriptableObjects as data containers not only frees you from attaching your scripts to GameObjects but also gives you the freedom to create singleton assets from the Asset menu. Both added features make scriptable objects a good fit to address testing concerns with the Singleton pattern, and it is much easier for non-programming members of your team to work with them.

Your last task in this chapter is to create a generic singleton as a ScriptableObject asset in the project. In the Scripts folder, create a new C# script, name it ScriptableSingleton, and update its code to match the following code. This script creates a generic ScriptableObject class that we can use to fetch a unique instance from the project resources when queried:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
// 1
public...

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Key benefits

Craft engaging Unity 2023 games while mastering design patterns like Singleton, Object Pool, and more
Write clean, reusable C# code using creational, behavioral, and structural patterns, tailored for the game development environment
Go beyond basic design pattern usage and learn to customize and extend them for your unique game design needs

Description

Struggling to write maintainable and clean code for your Unity games? Look no further! Learning Design Patterns with Unity empowers you to harness the fullest potential of popular design patterns while building exciting Unity projects. Through hands-on game development, you'll master creational patterns like Prototype to efficiently spawn enemies and delve into behavioral patterns like Observer to create reactive game mechanics. As you progress, you'll also identify the negative impacts of bad architectural decisions and understand how to overcome them with simple but effective practices. By the end of this Unity 2023 book, the way you develop Unity games will change. You'll emerge not just as a more skilled Unity developer, but as a well-rounded software engineer equipped with industry-leading design patterns.

Who is this book for?

This book is your perfect companion if you're a Unity game developer looking to level up your C# skills and embrace industry standards for building robust games. Knowledge of Unity and basic C# programming is recommended.

What you will learn

Implement a persistent game manager using the Singleton pattern
Spawn projectiles efficiently with Object Pooling for optimized performance
Build a flexible crafting system using the Factory Method pattern
Design an undo/redo system for player movement with the Command pattern
Implement a state machine to control a two-person battle system
Modify existing character objects with special abilities using the Decorator pattern

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Amazon verified reviews

Emmanuel Mensah Oct 29, 2024

Harrison Ferrone’s book is a fantastic introduction to design patterns for Unity developers. Right from the basics, like the difference between software architecture and software design, to advanced patterns such as Visitor and Decorator, Ferrone guides you with clarity and enthusiasm. The examples are relevant and explained in a way that builds a solid understanding without overwhelming the reader. I especially appreciated how he addresses common pitfalls with each pattern, which is often overlooked in technical books. It’s a well-organised guide for game developers wanting to produce clean, maintainable, and scalable code in Unity.

Amazon Verified review

Danial Jumagaliyev Oct 25, 2024

It's full of great tips in organizing your code in Unity and I recommend checking it out if you are into learning game development with the Unity engine.

Florida MTB’r Oct 14, 2024

This book breaks down many important game development techniques. Many of which I have heard before but never worked with. This does a good job of introducing a design pattern, then dives deeper into making it its most efficient / clean implementation.The book offers sample projects to download. I never used those but was able to follow along with the sample Unity code and setup regardless.I now have integrated many of these techniques into my usual game dev process. Great book for learning at an intermediate level.

Tyree Weston Sep 16, 2024

A good read to build on existing knowledge. As the title suggests, this book is a way to explain common design patterns and shed some light on different situation that can be made more efficient to apply said patterns. That saidTHIS IS NOT A BOOK FOR BEGINNERSThis is not intro to Unity, intro to C#, or an intro to programming in general. The intended audience who will gain information from this book need to be generally familiar with unity. With that in mind, Harrison Ferrone did a great job explaining the concept presented and provided excellent examples.

Paul Southworth Sep 10, 2024

This book seems to cover quite a range of design patterns and even includes things on how it's been used within a game setting using the Unity engine.although this book is not meant for beginners it's a book that you can keep within your shelf, especially If you end up looking at the overview of the different chapters. you can see an explanation of how that specific pattern is being used

Learning Design Patterns with Unity: Learn the secret of popular design patterns while building fun, efficient games in Unity 2023 and C#

What do you get with Print?

Learning Design Patterns with Unity

Managing Access with the Singleton Pattern

Technical requirements

Breaking down the pattern

Updating a MonoBehavior into a persistent singleton

Creating a generic singleton

Adding thread safety to the generic singleton

Creating singletons as ScriptableObjects

Summary

Further reading

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Learning Design Patterns with Unity: Learn the secret of popular design patterns while building fun, efficient games in Unity 2023 and C#

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