Added the service locator pattern

Author: Habrador

Assets/Patterns/15. Service Locator.meta

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+using System.Collections;
+using System.Collections.Generic;
+using UnityEngine;
+
+namespace ServiceLocator.AudioService
+{
+    //Implementation of the Service Locator example from the book Game Programming Patters
+    //This class used to test that the implementation is working
+    public class GameController : MonoBehaviour
+    {
+
+        void Start()
+        {
+            //Register the service provider in the Locator
+            ConsoleAudio audio = new ConsoleAudio();
+
+            Locator.Provide(audio);
+            //Locator.Provide(null);
+        }
+
+
+        void Update()
+        {
+            Audio audio = Locator.GetAudio();
+
+            if (Input.GetKeyDown(KeyCode.P))
+            {
+                audio.PlaySound(23);
+            }
+            else if (Input.GetKeyDown(KeyCode.S))
+            {
+                audio.StopSound(23);
+            }
+            else if (Input.GetKeyDown(KeyCode.Space))
+            {
+                audio.StopAllSounds();
+            }
+        }
+    }
+}

Assets/Patterns/15. Service Locator/Audio service locator.meta

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+using System.Collections;
+using System.Collections.Generic;
+using UnityEngine;
+
+namespace ServiceLocator.AudioService
+{
+    //Service provider parent class
+    //This is the abstract class that determines which methods the service will be exposing
+    public abstract class Audio 
+    {
+        public abstract void PlaySound(int soundID);
+
+        public abstract void StopSound(int soundID);
+
+        public abstract void StopAllSounds();
+    }
+}

Assets/Patterns/15. Service Locator/Audio service locator/Scripts.meta

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+using System.Collections;
+using System.Collections.Generic;
+using UnityEngine;
+
+namespace ServiceLocator.AudioService
+{
+    //Service provider child class
+    public class ConsoleAudio : Audio
+    {
+        public override void PlaySound(int soundID)
+        {
+            Debug.Log($"Sound {soundID} has started");
+        }
+
+        public override void StopSound(int soundID)
+        {
+            Debug.Log($"Sound {soundID} has stopped");
+        }
+
+        public override void StopAllSounds()
+        {
+            Debug.Log($"All sounds have stopped");
+        }
+    }
+}

Assets/Patterns/15. Service Locator/Audio service locator/Scripts/GameController.cs

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+using System.Collections;
+using System.Collections.Generic;
+using UnityEngine;
+
+namespace ServiceLocator.AudioService
+{
+    //This is the service locator
+    public class Locator
+    {
+        private static NullAudio nullService;
+    
+        private static Audio service;
+
+
+        static Locator()
+        {
+            nullService = new NullAudio();
+
+            //Init with null in case we forget to inject a reference to Audio
+            service = nullService;
+        }
+        
+
+        //Does the locating
+        public static Audio GetAudio()
+        {        
+            return service;
+        }
+        
+
+        //Use dependency injection to get a reference to the audio service we need
+        //Call this method before you do anything else with the audio
+        public static void Provide(Audio _service)
+        {
+            //Sometimes we want to set it to null if we want to disable audio in the game
+            if (_service == null)
+            {
+                service = nullService;
+            }
+            else
+            {
+                service = _service;
+            }
+        }
+    }
+}

Assets/Patterns/15. Service Locator/Audio service locator/Scripts/GameController.cs.meta

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+using System.Collections;
+using System.Collections.Generic;
+using UnityEngine;
+
+namespace ServiceLocator.AudioService
+{
+    //Service provider child class
+    //Used if the service locator hasnt been given a reference to a service provider or if we dont want to play audio
+    public class NullAudio : Audio
+    {
+        public override void PlaySound(int soundID)
+        {
+            Debug.Log("Do nothing");
+        }
+
+        public override void StopSound(int soundID)
+        {
+            Debug.Log("Do nothing");
+        }
+
+        public override void StopAllSounds()
+        {
+            Debug.Log("Do nothing");
+        }
+    }
+}