![\"\"](\"https:\/\/docs.sisus.co\/init-args\/wp-content\/uploads\/sites\/6\/2026\/10\/missing-init-argument.png\")
<\/p>\n
Sometimes, however, you might want to create a client that can work perfectly fine without receiving some of its dependencies from the outside through its Init method. For example, a component might log messages using a logger injected through its Init method when provided one, but fallback to using a default logger implementation if none has been provided.<\/p>\n
![\"\"](\"https:\/\/docs.sisus.co\/init-args\/wp-content\/uploads\/sites\/6\/2026\/10\/client-optional-init-argument.png\")
<\/p>\n
You can let Init(args) know about such optional Init arguments by marking them as nullable.<\/p>\n
Marking Init Arguments Optional<\/h1>\n
There are a couple of different ways to let Init(args) know that an Init argument is optional. They all have the same effect, so you can use whichever one you prefer.<\/p>\n
Nullable Reference Types<\/h2>\n
If you have nullable reference types<\/a> enabled, you can make the Init parameter have a nullable type:<\/p>\n Add the [AllowNull]<\/a> attribute to the parameter:<\/p>\n Give the parameter in the If you have an Initializer<\/a> with a nested This can be useful when assigning the argument is optional when the client is configured using this particular initializer, but not necessarily in other situations.<\/p>\n When an optional Init argument is missing, no warning is shown about it in the Inspector, even when Null Argument Guard is enabled.<\/p>\n <\/p>\n <\/p>\n When an optional Init argument is missing, no warning is logged to the Console in Edit Mode, even when Null Argument Guard is enabled.<\/p>\n When the client receives When an optional Init argument is missing when the client is loaded, the client does not wait in a disabled state for it to become available, even if it has been configured to wait for services<\/a> using Since an optional argument can be One option is to check for null every time before using the dependency:<\/p>\n Another option is to replace the missing dependency with a fallback instance during the client’s initialization:<\/p>\n If an Init parameter is given a default value other than A field initializer in the nested Marking an Init argument optional only affects that one argument; the Null Argument Guard can still keep protecting all the other arguments of the client.<\/p>\n If you want to allow a component to be loaded without it receiving any dependencies in its Init method at all, you can use What Are Optional Init Arguments? By default Init(args) assumes that every Init argument a client receives is required. If an argument is missing, and the Null Argument Guard is enabled, you get warnings shown in the Inspector, logged to the Console in Edit Mode and exceptions thrown at runtime. Sometimes, however, you might want to ..<\/p>\n#nullable enable\r\nusing Sisus.Init;\r\n\r\nclass Enemy : MonoBehaviour<IPlayer, ILogger>\r\n{\r\n IPlayer player = null!;\r\n ILogger logger = null!;\r\n\r\n protected override void Init(IPlayer player, ILogger?<\/strong> logger)\r\n {\r\n this.player = player;\r\n this.logger = logger ?? new DefaultLogger();\r\n }\r\n}<\/pre>\n[AllowNull] Attribute<\/h2>\n
using System.Diagnostics.CodeAnalysis;\r\nusing Sisus.Init;\r\n\r\nclass Enemy : MonoBehaviour<IPlayer, ILogger>\r\n{\r\n IPlayer player;\r\n ILogger logger;\r\n\r\n protected override void Init(IPlayer player, [AllowNull]<\/strong> ILogger logger)\r\n {\r\n this.player = player;\r\n this.logger = logger ?? new DefaultLogger();\r\n }\r\n}<\/pre>\nDefault Value Of Null<\/h2>\n
Init<\/code> method a default value of null<\/code>:<\/p>\nusing Sisus.Init;\r\n\r\nclass Enemy : MonoBehaviour<IPlayer, ILogger>\r\n{\r\n IPlayer player;\r\n ILogger logger;\r\n\r\n protected override void Init(IPlayer player, ILogger logger = null)\r\n {\r\n this.player = player;\r\n this.logger = logger;\r\n }\r\n}<\/pre>\nInitializer Init Class<\/h2>\n
Init<\/code> class, you can make the field that corresponds with the Init argument have a nullable type or add the [AllowNull]<\/code> or [MaybeNull]<\/code> attribute to it to mark it as optional:<\/p>\n#nullable enable\r\nusing Sisus.Init;\r\n\r\nclass EnemyInitializer : CustomInitializer<Enemy, IPlayer, ILogger>\r\n{\r\n class Init\r\n {\r\n IPlayer Player = default;\r\n ILogger? Logger = default;\r\n }\r\n\r\n protected override void InitTarget(Enemy enemy, IPlayer player, ILogger? logger)\r\n {\r\n ((IInitializable<IPlayer, ILogger>)enemy).Init(player, logger ?? new DefaultLogger());\r\n }\r\n}<\/pre>\n![\"\"](\"https:\/\/docs.sisus.co\/init-args\/wp-content\/uploads\/sites\/6\/2026\/10\/initializer-optional-init-argument.png\")
<\/p>\nWhat Changes?<\/h1>\n
Inspector<\/h2>\n
Edit Mode<\/h2>\n
Runtime<\/h2>\n
null<\/code> for an optional argument, no InvalidInitArgumentsException<\/code> is thrown. This is the case regardless of whether the arguments are passed to the client by an Initializer, or manually in code:<\/p>\ngameObject.AddComponent<Enemy, IPlayer, ILogger>(player, null);<\/pre>\n
Async Initialization<\/h2>\n
[Init(WaitForServices = true)]<\/code>.<\/p>\nHandling Optional Dependencies<\/h1>\n
null<\/code>, the client must be ready to handle that situation.<\/p>\nvoid Attack()\r\n{\r\n player.TakeDamage(damage);\r\n logger?.Log($\"{name} attacked the player.\");\r\n}<\/pre>\nprotected override void Init(IPlayer player, ILogger? logger = null)\r\n{\r\n this.player = player;\r\n this.logger = logger ?? new NullLogger();\r\n}<\/pre>\nDefault Values<\/h1>\n
null<\/code>, that value is used as the initial value of the argument when an Initializer is attached to the client:<\/p>\nclass Enemy : MonoBehaviour<IPlayer, float>\r\n{\r\n protected override void Init(IPlayer player, float moveSpeed = 5f)\r\n {\r\n ...\r\n }\r\n}<\/pre>\nInit<\/code> class of a custom Initializer can be used for the same purpose, and takes precedence over the Init parameter’s default value when the initializer in question is attached to the client:<\/p>\nclass EnemyInitializer : Initializer<Enemy, IPlayer, float>\r\n{\r\n class Init\r\n {\r\n IPlayer Player = default;\r\n float MoveSpeed = 10f;\r\n }\r\n}<\/pre>\nOptional Init Arguments vs Optional Initialization<\/h1>\n
[Init(Enabled = false]<\/code> instead. See [Init] attribute<\/a> for more information.<\/p>\n","protected":false},"excerpt":{"rendered":"