@ue-too/being / index / createStateWidener

関数: createStateWidener()

createStateWidener<E2, C2, S2, O2>(): <E1, C1, S1, O1>(state) => WidenedState<E1, C1, S1, O1, E2, C2, S2, O2>

定義: expansion.ts:55

Creates a function that retypes a state for a machine with a superset of its events, states, context and outputs.

型パラメーター

E2

E2

C2

C2 extends BaseContext

S2

S2 extends string

O2

O2 extends Partial<Record<keyof E2, unknown>> = DefaultOutputMapping<E2>

戻り値

<E1, C1, S1, O1>(state): WidenedState<E1, C1, S1, O1, E2, C2, S2, O2>

型パラメーター

E1

E1

C1

C1 extends BaseContext

S1

S1 extends string

O1

O1 extends Partial<Record<keyof E1, unknown>>

パラメータ

state

State<E1, C1, S1, O1>

戻り値

WidenedState<E1, C1, S1, O1, E2, C2, S2, O2>

Remarks

At runtime a state only ever consults its own reactions, so an original state behaves correctly inside a wider machine: events it does not list come back handled: false. The State type is invariant in its generics, though, so the compiler rejects the registration. This helper is that cast, guarded so that a target which narrows the original produces a type error instead of a lie.

Name the target generics once, then widen as many original states as needed.

例

const widen = createStateWidener<ExpEvents, ExpContext, ExpStates, ExpOut>();
const states = { PAN: widen(new PanState()), IDLE: widen(new KmtIdleState()) };