![\"\"](\"https:\/\/docs.sisus.co\/init-args\/wp-content\/uploads\/sites\/6\/2021\/07\/service-tag.png\")
<\/h2>\nGlobal services can receive callbacks during select lifetime events, even if they don’t derive from MonoBehaviour, by implementing one of the following interfaces:<\/p>\n
- \n
- IAwake\u00a0<\/b>\u2013 Awake is executed immediately following the initialization of the service instance. The Init functions of all services that implement an IInitializable<T><\/a> interface are always executed before any Awake functions are.<\/li>\n
- I<\/b>O<\/b>nEnable<\/b> \u2013 OnEnable is executed following the initialization of the service instance. The Awake functions of all services that implement IAwake are always executed before any OnEnable functions are.<\/li>\n
- IStart<\/b> \u2013 Start is executed following the initialization of the service instance. The OnEnable functions of all services that implement IOnEnable are always executed before any Start functions are.<\/li>\n
- I<\/b>U<\/b>pdate<\/b>\u00a0\u2013\u00a0Receive callback during the Update event.<\/li>\n
- I<\/b>F<\/b>ixedUpdate<\/b>\u00a0\u2013\u00a0Receive callback during the FixedUpdate\u00a0event.<\/li>\n
- I<\/b>L<\/b>ateUpdate<\/b>\u00a0\u2013\u00a0Receive callback during the LateUpdate\u00a0event.<\/li>\n
- IOnDisable <\/strong>– Receive callback when the application is quitting or when exiting play mode in the editor.<\/li>\n
- IOnDestroy <\/strong>– Receive callback when the application is quitting or when exiting play mode in the editor.<\/li>\n<\/ol>\n
Additionally if your service class implements the IDiposable<\/a> interface then IDispose will be called for it when the application is quitting or when exiting play mode in the editor.<\/p>\n<\/div>\n<\/div>\n<\/article>\n
\n \nRegistering Services Manually In Code<\/h1>\n
In addition to registering services automatically using the [Service] attribute, it is possible to register them manually in code as well.<\/p>\n
This might be useful for example if you want to dynamically swap your services with different ones based on some conditional logic.
\nFor example you could swap the KeyboardInputManager to GamepadInputManager when the user changes their input method in the settings.<\/p>\nTo manually register a global service<\/a> use the Service.Set<\/em> method.<\/p>\n
To make sure that the service gets registered before the Awake method on any clients components or their initializers is executed, you can add the InitOrder attribute with Category set to ServiceInitializer to the component that does the registering.<\/p>\n
[InitOrder(Category.ServiceInitializer)]\r\npublic class InputManager : MonoBehaviour, IInputManager\r\n{\r\n void OnEnable() => Service.Set<IInputManager>(this);\r\n void OnDisable() => Service.Unset<IInputManager>(this);\r\n}<\/pre>\n<\/div>\n<\/article>\nTo manually register a local service<\/a> limited to only some clients based on their location in the scene hierarchies, use the Service.AddFor<\/em> method.<\/p>\n
[InitOrder(Category.ServiceInitializer)]\r\npublic class Player : MonoBehaviour\r\n{\r\n void Awake() => Service.AddFor(Clients.InChildren, this);\r\n void OnDestroy() => Service.RemoveFrom(Clients.InChildren, this);\r\n}<\/pre>\nUsing Services<\/span><\/p>\n
\n \nTo automatically receive the InputManager service during initialization you can have your class derive from MonoBehaviour<InputManager>. It will then receive the InputManager object in its Init function, making it possible to assign it to a member variable.<\/p>\n
public class Player : MonoBehaviour<InputManager>\r\n{\r\n private InputManager inputManager;\r\n\r\n protected override void Init(InputManager inputManager)\r\n {\r\n this.inputManager = inputManager;\r\n }\r\n}<\/pre>\nThis means that the Player component could exist as part of a scene that is loaded or a prefab that is instantiated without any arguments being provided manually, and Init would still get called with the InputManager service.<\/p>\n
Note that the Init function will only get automatically called during initialization if all the Init arguments the client expects are services.<\/p>\n
If one or more arguments are not services, then you will need to manually provide all the arguments when initializing the client.<\/p>\n
For example, consider this client that requires one service object and one object that is not a service:<\/p>\n
public class Player : MonoBehaviour<InputManager, Camera>\r\n{\r\n private InputManager inputManager;\r\n private Camera firstPersonCamera;\r\n\r\n protected override void Init(InputManager inputManager, Camera firstPersonCamera)\r\n {\r\n this.inputManager = inputManager;\r\n this.firstPersonCamera = firstPersonCamera;\r\n }\r\n}<\/pre>\nYou can retrieve the cached instance of any service manually using Service.Get<T>() or Service.GetFor<T>(Object).<\/p>\n
var inputManager = Service.Get<InputManager>();<\/pre>\n
Then you need to pass that instance to the client when it is being created.<\/p>\n
For example if you are creating the client by instantiating it from a prefab, you can use the Prefab.Instantiate function.<\/p>\n
var inputManager = Service.Get<InputManager>();\r\nvar firstPersonCamera = Camera.main;\r\n\r\nvar playerPrefab = Resources.Load<Player>(\"Player\");\r\nplayerPrefab.Instantiate(inputManager, firstPersonCamera);<\/pre>\n
Or if the client is being built from scratch at runtime, you can use the GameObject.AddComponent function that accepts initialization arguments.<\/p>\n
var playerGameObject = new GameObject(\"Player\");\r\nplayerGameObject.AddComponent(inputManager, firstPersonCamera);<\/pre>\n
If the client is a scene object, you can generate an Initializer<\/a> to provide the arguments to the client.
\nWhen using Initializers all service arguments are passed to the client automatically, so you only need to assign the other arguments using the Inspector.<\/p>\n\nReacting To Changing Services<\/span><\/h1>\n<\/div>\n<\/div>\n<\/article>\n
In cases where your services might change throughout the lifetime of the application, you may want to make sure clients of the services are always using the most recently registered services.<\/p>\n
To do this you can subscribe receive callbacks a service instance changes to a different, using the Service.AddInstanceChangedListener method.<\/p>\n
When you do this you should also remember to unsubscribe using Service.RemoveInstanceChangedListener when the listener gets destroyed.<\/p>\n
public class Player : MonoBehaviour<IInputManager>\r\n{\r\n private IInputManager inputManager;\r\n\r\n protected override void Init(IInputManager inputManager)\r\n {\r\n this.inputManager = inputManager;\r\n }\r\n\r\n private void OnEnable()\r\n {\r\n Service.AddInstanceChangedListener(OnInputManagerInstanceChanged);\r\n }\r\n\r\n \u00a0private void OnDisable()\r\n {\r\n Service.RemoveInstanceChangedListener(OnInputManagerInstanceChanged);\r\n }\r\n\r\n private void OnInputManagerInstanceChanged(IInputManager newInstance)\r\n {\r\n inputManager = newInstance;\r\n }\r\n}<\/pre>\nBest Practices<\/h1>\n
- \n
- Consider using the Preload Scene<\/a> pattern and [Service(LoadScene = name)]<\/em> for scene-based global services, if you want make sure they are always initialized before any clients in other scenes.<\/li>\n
- If a scene-based service does not exist for the entire lifetime of the application, use a Service Tag<\/a> or Services component<\/a> to register it instead of a [Service] attribute.<\/li>\n
- If you want to instantiate prefab-based services synchronously, [Service(ResourcePath = path)]<\/em> can be used.<\/li>\n
- Consider avoiding using DontDestroyOnLoad<\/a> to convert scene objects into persistent global services – if the objects should hold any references to other objects in its original scene, or vice versa, those could easily break if the original scene is unloaded or reloaded at some point. For this reason it can be safer to simply never unload the scene(s) that contain global services as a whole, so that all objects in the scene are guaranteed to have the same lifetime.<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"
Defining a Global Service You can define a global service in Init(args) by simply adding the [Service] attribute to any class: [Service] class GameManager { } This will instruct Init(args) to automatically create and cache a single instance of the the class when the project starts. Ready To Use Before Scene Load All global services ..<\/p>\n
- If a scene-based service does not exist for the entire lifetime of the application, use a Service Tag<\/a> or Services component<\/a> to register it instead of a [Service] attribute.<\/li>\n
- I<\/b>O<\/b>nEnable<\/b> \u2013 OnEnable is executed following the initialization of the service instance. The Awake functions of all services that implement IAwake are always executed before any OnEnable functions are.<\/li>\n