An easy to understand implementation of reactive values and objects

Inspired by GetX, observable_ish, and similar packages

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Features

Class Use-case
RxBool A reactive bool
RxDateTime A reactive DateTime
RxDouble A reactive double
RxDuration A reactive Duration
RxInt A reactive int
RxString A reactive string
RxValue A reactive value
RxObject A reactive object
RxList A reactive list
RxMap A reactive map
RxSet A reactive set
RxComposite A composite of Rx objects
RxCompositeList A composite version of RxList
RxCompositeMap A composite version of RxMap
RxCompositeSet A composite version of RxSet

NOTE: Because int cannot be extended, the type-checker will not be able to properly infer the return type of all methods on RxInt

See fast_rx_flutter for Flutter-specific components

Usage

import 'package:fast_rx/fast_rx.dart';

void example() {
  // ...

  final count = 0.rx;

  // All primitive methods are available on their reactive versions
  // NOTE: The type checker cannot automatically infer the return type of all
  // methods
  count + 2; // This returns a num
  count.value + 2; // This returns an int

  // ...

  // ignore: avoid_print
  count.stream.listen(print);

  // ...

  // Will print the value
  count.value = 1;

  final list = <int>[].rx;
  // Will only notify after the run block completes
  list.run(() {
    list.add(1);
    list.add(2);
  });
}

RxObject

RxObject can be used to create reactive objects of classes outside of your control. If an object is within your control, consider making fields reactive instead.

import 'package:fast_rx/fast_rx.dart';

class Tuple<T1, T2> {
  T1 item1;
  T2 item2;

  Tuple(this.item1, this.item2);

  Tuple.from(Tuple<T1, T2> other) : this(other.item1, other.item2);

  @override
  bool operator ==(Object other) =>
      other is Tuple<T1, T2> && other.item1 == item1 && other.item2 == item2;

  @override
  int get hashCode => Object.hash(item1, item2);
}

class RxTuple<T1, T2> extends RxObject<Tuple<T1, T2>> implements Tuple<T1, T2> {
  RxTuple(super.value);

  @override
  T1 get item1 => value.item1;

  @override
  set item1(T1 value) => notifyIfChanged(() => unregisteredValue.item1 = value);

  @override
  T2 get item2 => value.item2;

  @override
  set item2(T2 value) => notifyIfChanged(() => unregisteredValue.item2 = value);

  @override
  Tuple<T1, T2> copyValue() => Tuple.from(unregisteredValue);

  @override
  bool shouldNotify(Tuple<T1, T2> oldValue) => oldValue != unregisteredValue;
}

extension RxTupleExtension<T1, T2> on Tuple<T1, T2> {
  RxTuple<T1, T2> get rx => RxTuple<T1, T2>(this);
}

RxComposite

An RxComposite is an Rx that contains other Rx objects, and notifies with them.

Create and use composite versions of RxIterables:

import 'package:fast_rx/fast_rx.dart';

void example() {
  final compositeList = [0.rx].rx.composite;
  final compositeMap = {0: 1.rx}.rx.composite;
  final compositeSet = {0.rx}.rx.composite;

  // All of these will cause their parent to notify
  compositeList[0].value = 1;
  compositeMap[0]!.value = 1;
  compositeSet.first.value = 1;
}

Custom RxComposite:

import 'package:fast_rx/fast_rx.dart';

class Composite extends RxComposite {
  final a = 1.rx;
  final b = 2.rx;
  final c = 3.rx;

  Composite() {
    // Register all rx fields so that this object notifies with them
    addRx(a);
    addRx(b);
    addRx(c);
  }
}

Testing custom Rx

Custom Rx objects can be tested for valid registration and notifications using fast_rx_test.

Additional information

See fast_ui for more information

Libraries

fast_rx