sign 0.0.4+2

Basic state management base for dart. Sign inspired QT framework signal-slot architecture.

Sign

Basic state management base for dart. Sign inspired QT framework signal-slot architecture.

This package is supported all platforms include dart sdk.

For Flutter: sign_flutter

Flutter package has some Widgets for signal and some extensions to generate signal from ChangeNotifier and ValueNotifier.

1) What is Signal?

Signal is simply a class that triggers a function when its value changes (or on request).

In this regard, Signal is very similar to Flutter's ChangeNotifier or ValueNotifier, GetX's observable, or Provider's StateNotifier.

Signal has some minor differences. First it is independent of Flutter. And its so simple, it lacks the long lines of code that control so many cases.

It also works with Slot instead of callbacks.

Basically there are only 3 things:

1. Signal : Signal has a value. This is the class that triggers the function when value changes or sign() called.

2. Slot : Slot can be added to desired Signals. Signal triggers are handled with Slot.onValue when added to a Signal.

3. MultiSignal : MultiSignal is both a Slot and a Signal. It collects triggers from different Signals as one Slot and works like a single Signal.

How To Use?

1. Define a Signal implementation or create a Signal from any variable.

/// Create a Signal from a variable
final Signal<int> signal = 0.signal;

void f() {
  signal.value++;
  // OR
  signal.sign();
}

/// Define signal implementation
class MySignal extends Signal<int> {
  MySignal() : super(0);

  void changeSomething() {
    // Change signal value to trigger signal
    value = newValue;

    // Or use sign() to trigger signal
    sign();
  }
}

2. Define a Slot implementation.

class MySlot extends Slot<int> {
  MySlot() : super();

  @override
  void onValue(int value) {
    // Do something
  }
}

In Flutter you can create states that are themselves a slot. You can use aSignal.builder() or SlotWidget for this.

3. Add a Slot to a Signal.

void f() {
  // Add a Slot to a Signal
  signal.addSlot(MySlot());
}

Special Signal Classes

If you want to trigger changes on List and Map, you don't need to use an expression like value = newList.

Statements like these reduce performance significantly.

You can use SignalList and SignalMap instead.

SignalList and SignalMap trigger a signal in any case that changes the collection content.

final signalList = <int>[].signalList;
final signalMap = <String,String>{}.signalMap;
void f() {
  signalList.add(1); // triggered

  signalList.remove(1); // triggered

  signalList.clear(); // triggered

  signalList[0] = 10; // triggered
  
  signalMap['a'] = 'b'; // triggered
  
  signalMap.remove('a'); // triggered
  
}

To create a SignalList, use SignalList constructors or create with list.signalList.

To create a SignalMap, use SignalMap constructors or create with map.signalMap.

GlobalSignal / GlobalSlot

GlobalSlots are triggered by changes in same generic type GlobalSignal without the need to add to GlobalSignals.

GlobalSignal must be created only once or disposed before creating a new instance.

void main(){
  var globalCounter = GlobalCounter();

  GlobalCountSlot('a');
  GlobalCountSlot('b');
  GlobalCountSlot('c');
  GlobalCountSlot('d');
  GlobalCountSlot('e');
  
  
  globalCounter.value++;
  // GlobalCountSlot 'a', 'b', 'c', 'd', 'e' triggered
}

class GlobalCounter extends GlobalSignal<int> {
  GlobalCounter() : super(0);

  void increment() {
    value++;
  }

  void decrement() {
    value--;
  }
}

class GlobalCountSlot extends GlobalSlot<int, GlobalCounter> {
  GlobalCountSlot(this.name);

  String name;

  @override
  void onValue(int value) {
    print('GlobalCountSlot :  $name : $value');
  }
}