Design Pattern: Understanding the Singleton Pattern Through a Real-Life Story — Unity

Design patterns can often seem abstract when first introduced, but relating them to everyday scenarios makes them much easier to grasp. In this blog, we’ll learn about the Singleton Pattern using a relatable real-life story and a practical Unity script.

What is the Singleton Pattern?

The Singleton Pattern ensures a class has only one instance and provides a global access point to it. Think of it as a way to guarantee there’s only one CEO for a company or one president for a country at any given time.

The Singleton in Real Life: The Neighborhood Lighthouse

Imagine a seaside neighborhood where sailors rely on a lighthouse to navigate their ships safely to the harbor at night. Here’s the catch:

• The neighborhood can only afford one lighthouse.

• Everyone must look to this single lighthouse for guidance; having multiple lighthouses would confuse the sailors.

• No matter how many requests are made to check the lighthouse, the same one is referenced every time.

This lighthouse is like a Singleton – it exists only once and is accessible globally.

Applying the Singleton Pattern in Unity

Let’s use the lighthouse example to create a simple Unity script that implements the Singleton Pattern.

Step 1: Define the Singleton

Here’s the script for the lighthouse:

using UnityEngine;
public class Lighthouse : MonoBehaviour
{
 public static Lighthouse Instance { get; private set; } // Global access point to the Singleton

 private void Awake()
 {
   if (Instance != null && Instance != this)
   {
     Debug.LogWarning("Another Lighthouse instance detected. Destroying duplicate.");
     Destroy(gameObject);
   }
   else
   {
     Instance = this; // Assign this instance
     DontDestroyOnLoad(gameObject); // Keep the lighthouse persistent across scenes
   }
 }

 public void GuideSailors()
 {
   Debug.Log("Lighthouse guiding sailors with its beacon.");
 }
}