ModFeature

Helper class for mods that want to represent their individual features as classes. Extend your mod features from this class in order to enable the @Callback and @CustomCallback decorators that automatically subscribe to callbacks.

It is recommended that you use the initModFeatures helper function to instantiate all of your mod classes (instead of instantiating them yourself). This is so that any attached v objects are properly registered with the save data manager; see below.

If you are manually instantiating a mod feature yourself, then:

• You must pass your upgraded mod as the first argument to the constructor.
• In almost all cases, you will want the callback functions to be immediately subscribed after instantiating the class. However, if this is not the case, you can pass false as the optional second argument to the constructor.

If your mod feature has a property called v, it will be assumed that these are variables that should be managed by the save data manager. Unfortunately, due to technical limitations with classes, this registration will only occur if you initialize the class with the initModFeatures helper function. (This is because the parent class does not have access to the child's properties upon first construction.)

Constructors

constructor

• new ModFeature(mod, init?): ModFeature

Parameters

Name	Type	Default value
mod	ModUpgraded	undefined
init	boolean	true

Returns

ModFeature

Defined in

packages/isaacscript-common/src/classes/ModFeature.ts:109

Properties

shouldCallbackMethodsFire

• Protected shouldCallbackMethodsFire: null | <T>(vanilla: T, modCallback: T extends true ? ModCallback : ModCallbackCustom, ...callbackArgs: readonly unknown[]) => boolean = null

An optional method that allows for conditional callback execution. If specified, any class method that is annotated with a @Callback or @CallbackCustom decorator will only be fired if the executed conditional function returns true.

This property is used to easily turn entire mod features on and off (rather than repeating conditional logic and early returning at the beginning of every callback function).

Since the specific information for the firing callback is passed as arguments into the conditional method, you can also write logic that would only apply to a specific type of callback.

By default, this is set to null, which means that all callback methods will fire unconditionally. Override this property in your class if you need to use it.

The function has the following signature:

<T extends boolean>(
  vanilla: T, // Whether this is a vanilla or custom callback.
  modCallback: T extends true ? ModCallback : ModCallbackCustom,
  ...callbackArgs: unknown[] // This would be e.g. `pickup: EntityPickup` for the `POST_PICKUP_INIT` callback.
) => boolean;

Defined in

packages/isaacscript-common/src/classes/ModFeature.ts:93

---

initialized

• initialized: boolean = false

Whether the feature has registered its callbacks yet.

This will almost always be equal to true unless you explicitly passed false to the second argument of the constructor.

Defined in

packages/isaacscript-common/src/classes/ModFeature.ts:107

Methods

init

▸ init(init?): void

Runs the Mod.AddCallback and ModUpgraded.AddCallbackCustom methods for all of the decorated callbacks. Also registers/unregisters the "v" variable on the save data manager.

Parameters

Name	Type	Default value	Description
init	boolean	true	Optional. Whether to initialize or uninitialize. Default is true.

Returns

void

Defined in

packages/isaacscript-common/src/classes/ModFeature.ts:123

---

uninit

▸ uninit(): void

Runs the Mod.RemoveCallback and ModUpgraded.RemoveCallbackCustom methods for all of the decorated callbacks.

This is just an alias for ModFeature.init(false).

Returns

void

Defined in

packages/isaacscript-common/src/classes/ModFeature.ts:152