armature_reactive 1.0.0

Lightweight MobX-style reactive primitives — Atom, Reaction, and automatic dependency tracking for pure Dart.

armature_reactive

Lightweight MobX-style reactive primitives — Atom, Reaction, and automatic dependency tracking — for pure Dart. No Flutter dependency; consumed by armature and armature_flutter but usable standalone.

Core primitives

Atom

A value-less reactive signal. Pair an atom with your own storage — call reportObserved() on read so the ambient reaction subscribes, and reportChanged() on write to fan out invalidations.

class Counter {
  final _atom = Atom();
  int _value = 0;

  int get value {
    _atom.reportObserved();
    return _value;
  }

  set value(int next) {
    if (next == _value) return;
    _value = next;
    _atom.reportChanged();
  }
}

Reaction

A side-effect that re-runs when any tracked atom changes. Use track() to open a dependency-scope — every Atom.reportObserved call inside wires that atom as a dependency.

final counter = Counter();
final reaction = Reaction(onInvalidate: () {
  print('dependencies changed');
});

reaction.track(() {
  print(counter.value); // reading inside track → tracked
});

counter.value = 2; // schedules onInvalidate on the next batch drain

Call reaction.clear() when done — detaches the reaction from every atom it observed.

Batching

Multiple writes inside Context.startBatch() / Context.endBatch() coalesce into a single invalidation pass. Useful when you want "N writes, 1 reaction fire". Use globalContext unless you've created your own Context.

globalContext.startBatch();
a.value = 1;
b.value = 2;
globalContext.endBatch();  // reactions observing a or b fire once

Reactions re-run until they stabilise (fixed-point); the iteration cap (ReactiveConfig.maxIterations, default 100) guards against oscillating cycles.

Install

dependencies:
  armature_reactive: ^0.1.0

Learn more

• armature — feature framework that builds Store / State on top of these primitives.
• Monorepo README — full architecture and examples.

License

MIT — see LICENSE.