Write elegant reactive cross-platform client side application using observable states and event emitters.

Provides:

1. Reactive Values
2. Reactive Lists
3. Reactive Sets
4. Reactive Maps
5. Event emitter

Observable-ish provides a light-weight non-intrusive reactive framework to build cross-platform UI. It uses Dart's asynchronous Streams to emit and listen to changes.

Various observable types like RxValue, RxList, RxSet and RxMap can be used to update UI automatically on changes. Events can be passed up the widget tree using event Emitter.

RxValue can be used to encapsulate a simple observable value.

RxValue exposes field value to get set current value.

main() {
  final rxInts = RxValue<int>(initial: 5);
  int got = rxInts.value; // Gets current value
  rxInts.value = 10;      // Sets current value
}

When a value that is different from the existing value is set, the change is notified through various ways explained in the section.

It provides few flexible ways to listen to changes:

1. onChange: Record of changes
2. values: Stream of new values
3. listen: Callback function with new value

main() {
  final rxInts = RxValue<int>(initial: 5);
  print(rxInts.value);  // => 5
  rxInts.values.listen((int v) => print(v));  // => 5, 20, 25
  rxInts.value = 20;
  rxInts.value = 25;
}

Binding an RxValue to a Stream (using method bindStream) or another RxValue (using method bind) changes its value when the source Stream emits or RxValue changes. This is very useful in scenarios where one would like to change a model's value or widget's property when control changes. For example, change a text field's value when a checkbox is toggled.

  textBox.value.bindStream(checkBox.checked.map((bool v) => v?'Female': 'Male'));

main() {
  final rxInts = RxValue<int>(initial: 5);
  print(rxInts.value);  // => 5
  rxInts.value = 10;
  rxInts.value = 15;
  rxInts.values.listen((int v) => print(v));  // => 15, 20, 25
  rxInts.value = 20;
  rxInts.value = 25;
}

Observable-ish is designed to be non-intrusive. The philosophy is to separate the model and its reactive cousin into different classes.

class RxUser {
  final name = RxValue<String>();
  final age = RxValue<int>();
}

class User {
  final rx = RxUser();

  User({String name, int age}) {
    this.name = name;
    this.age = age;
  }

  String get name => rx.name.value;
  set name(String value) => rx.name.value = value;

  int get age => rx.age.value;
  set age(int value) => rx.age.value = value;
}

main() {
  final user = User(name: 'Messi', age: 30);
  user.age = 31;
  print(user.age);  // => 31
  print('---------');
  user.age = 32;
  user.rx.age.listen((int v) => print(v));  // => 20, 25
  user.age = 33;
  user.age = 34;
  user.age = 35;
}

Emitters provide a simple interface to emit and listen to events. It is designed to inter-operate with RxValue to provide maximum productivity.

1. on: Execute callback on event
2. listen: Similar to Stream
3. asStream: Obtain event as Stream

pipeTo pipes events to another Emitter.

pipeToValue pipes events to the given RxValue. This could be very helpful in binding events to observable values.

emit, emitOne, emitAll, emitStream and emitRxValue provides various ways to emit events using the Emitter

RxList notifies changes (addition, removal, clear, setting) of its elements.

RxList implements Dart's List.

Besides List's methods, RxList provides convenient methods like addIf and addAllIf to add elements based on a condition. This is very useful in writing UI in Dart DSL (as in Flutter and Nuts).

main() {
  final rxInts = RxList<int>();
  rxInts.onChange.listen((c) => print(c.element)); // => 5
  rxInts.addIf(5 < 10, 5);
  rxInts.addIf(5 > 9, 9);
}

Use assign and assignAll methods to replace existing contents of the list with new content.

onChange exposes a Stream of record of change of the List.

RxSet notifies changes (addition and removal) of its elements.

RxSet implements Dart's Set.

Besides Set's methods, RxSet provides convenient methods like addIf and addAllIf to add elements based on a condition. This is very useful in writing UI in Dart DSL (as in Flutter and Nuts).

main() {
  final rxInts = RxSet<int>();
  rxInts.onChange.listen((c) => print(c.element)); // => 5
  rxInts.addIf(5 < 10, 5);
  rxInts.addIf(5 > 9, 9);
}

onChange exposes a Stream of record of change of the Set.

bindBool and bindBoolValue allows removing or adding the given element based on the Stream of bools or RxValue of bools.

bindOneByIndexStream and bindOneByIndex allows removing all but the one element from a given Iterable of elements based on index Stream or RxValue.

RxMap notifies changes (addition, removal, clear, setting) of its elements.

RxMap implements Dart's Map.

Besides Map's methods, RxMap provides convenient methods like addIf and addAllIf to add elements based on a condition. This is very useful in writing UI in Dart DSL (as in Flutter and Nuts).

onChange exposes a Stream of record of change of the Map.