crate

weft_reactive

Weft reactive primitives.

A small, single-threaded, fine-grained reactive system (WASM in the browser is single-threaded, so Rc/RefCell is all we need):

Signal — a mutable value that records who reads it.
Effect — a side effect that re-runs whenever a signal it read changes.
Memo — a cached derived value that only notifies when it changes.
batch / untrack — control when effects run and what is tracked.
Owner — keeps effects alive and disposes them together (used for component lifetimes).

Structs

Effect
A side effect that tracks the signals it reads and re-runs when they change. The effect lives as long as a handle (or an Owner) holds it.
Memo
A cached derived value. Readers are only notified when the computed value actually changes (by PartialEq).
Owner
Owns the effects created inside [Owner::run], keeping them alive until [Owner::dispose]. Components use an owner to tie effects to their lifetime.
Signal
A reactive, shared, mutable value. Cloning a signal yields another handle to the same value.

pub fn batch<R>(f: impl FnOnce() -> R) -> R

Run f, deferring effect execution until it returns. Each affected effect runs at most once per (outermost) batch.

pub fn is_tracking() -> bool

Whether code is currently running inside an effect that tracks reads.

pub fn on_cleanup(f: impl FnOnce() + 'static)

Run f when the current Owner is disposed (for a component: when it stops being rendered). Without an owner, f never runs.

pub fn untrack<R>(f: impl FnOnce() -> R) -> R

Run f without tracking any signal reads.