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Signal

A reactive signal system for dependency tracking and cache invalidation.

Overview​

Signal is the reactive core of Locus, providing:

  • Dependency tracking
  • Automatic cache invalidation
  • Chainable animation API
  • Type-safe accessors

Core Types​

SignalValue<T>​

type SignalValue<T> = T | (() => T);

A signal value type that can be a static value or a function returning a value.

SignalGetter<T>​

interface SignalGetter<T> {
  (): T;
}

A signal getter interface.

SignalSetter<T, TOwner>​

interface SignalSetter<T, TOwner = void> {
  (value: SignalValue<T> | typeof DEFAULT): TOwner;
}

A signal setter interface that returns the owner object to support chaining.

Factory Functions​

createSignal​

function createSignal<T>(initial?: SignalValue<T>, owner?: object): Signal<T>;

Creates a basic signal.

const count = createSignal(0);
count(); // 0
count(1); // Set to 1

createComputed​

function createComputed<T, TOwner = void>(
  computation: () => T,
  owner?: TOwner,
): Computed<T>;

Creates a computed signal that automatically tracks dependencies.

const double = createComputed(() => count() * 2);

createEffect​

function createEffect(computation: () => void | (() => void)): void;

Creates a side effect that executes when dependencies change.

Signal Generators​

Signals support a chainable animation API:

signal
  .to(100, 1) // Tween to 100, duration 1 second
  .back(1) // Return, duration 1 second
  .wait(0.5) // Wait 0.5 seconds
  .to(0, 1); // Tween to 0, duration 1 second

Generator Methods​

MethodParametersDescription
to(value, duration, timing?, interpolation?)Tween to target value
back(duration, timing?, interpolation?)Return to initial value
wait(duration)Wait for specified time
run(task)Run thread task
do(callback)Execute callback function

Vector2 Signals​

const position = createSignal(new Vector2(0, 0));
position.x(); // 0
position.y(); // 0

// Chainable animation
position().to(new Vector2(100, 100), 1, easings.easeInOutQuad);