A low-invasive reactive system for Dart/Flutter.

In many frameworks, similar reactive base types are called "signals". Fundamentally, Oref has the same reactive base type as the signal concept. It is a value container that tracks dependencies when accessed and triggers side effects when changed.

What is reactivity?

Essentially, reactivity is a programming paradigm that allows us to handle changes declaratively. Many front-end frameworks emphasize its importance:

• Preact.js Signals
• Vue.js In-Depth Reactivity
• Solid Signals
• Dart: signals package

Installation

You can directly add Oref to any Dart project using this command:

dart pub add oref

Or modify your pubspec.yaml file:

dependencies:
  oref: latest

Basic Usage

import 'package:oref/oref.dart';

void main() {
  final count = ref(0);
  final double = derived(() => count.value * 2);
  final runner = effect(() {
    print('count: ${count.value}, double: ${double.value}');
  }, onStop: () {
    print('effect stopped');
  });

  count.value = 10; // Prints 'count: 10, double: 20'

  // Stop the effect
  runner.effect.stop(); // Prints 'effect stopped'

  count.value = 20; // No effect

  // If the effect is stopped, we can run it manually once.
  runner(); // Prints 'count: 20, double: 40'

  count.value = 30; // No effect
}