state_beacon 0.9.0

A reactive primitive for dart and flutter

Overview

A Beacon is a reactive primitive(signal) and simple state management solution for Dart and Flutter.

Usage

Flutter web demo: https://flutter-beacon.surge.sh/
All examples: https://github.com/jinyus/dart_beacon/examples

Click here for the full code.

Installation

dart pub add state_beacon

Usage

import 'package:state_beacon/state_beacon.dart';

Create a beacon

import 'package:flutter/material.dart';
import 'package:flutter_beacon/flutter_beacon.dart';

final counter = Beacon.writable(0);

// The future will be recomputed whenever the counter changes
final derivedFutureCounter = Beacon.derivedFuture(() async {
  final count = counter.value;
  return await counterFuture(count);
});

Future<String> counterFuture(int count) async {
  await Future.delayed(Duration(seconds: count));
  return '$count second has passed.';
}

Watch it in a widget

class Counter extends StatelessWidget {
  const Counter({super.key});

  @override
  Widget build(BuildContext context) {
    return Text(
      counter.watch(context).toString(),
      style: Theme.of(context).textTheme.headlineMedium!,
    );
  }
}

class FutureCounter extends StatelessWidget {
  const FutureCounter({super.key});

  @override
  Widget build(BuildContext context) {
    return switch (derivedFutureCounter.watch(context)) {
      AsyncData<String>(value: final v) => Text(v),
      AsyncError(error: final e) => Text('$e'),
      AsyncLoading() => const CircularProgressIndicator(),
    };
  }
}

Features

• WritableBeacon: Read and write values.
• ReadableBeacon: Read-only values.
• DebouncedBeacon: Debounce value changes over a specified duration.
• ThrottledBeacon: Throttle value changes based on a duration.
• FilteredBeacon: Update values based on filter criteria.
• TimestampBeacon: Attach timestamps to each value update.
• UndoRedoBeacon: Undo and redo value changes.
• BufferedBeacon: Create a buffer/list of values.
• StreamBeacon: Create beacons from Dart streams.
• FutureBeacon: Initialize beacons from futures.
• DerivedBeacon: Compute values reactively based on other beacons.
• DerivedFutureBeacon: Asynchronously compute values with state tracking.
• ListBeacon: Manage lists reactively.
• createEffect: React to changes in beacon values.
• doBatchUpdate: Batch multiple updates into a single notification.