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rodydavis/signals.dart ★9999⑂99

Type: SignalProvider

API reference and details for SignalProvider from signals.dart.

SignalProvider#

Kind: class  |  Package: package:signals_flutter

Class: SignalProvider#

A premium dependency-injection / state propagation widget that allows passing reactive signals down the Flutter widget tree using InheritedNotifier.

SignalProvider makes a signal accessible to all child widgets in the subtree. Any child widget that reads the signal using SignalProvider.of(context) will automatically rebuild when the signal's value changes, while parent widgets remain unaffected.

For version 7, SignalProvider is a stateful widget that manages the lifecycle of the created signal, ensuring it is persisted across parent rebuilds and automatically calling dispose() when the provider is unmounted to prevent memory leaks.

Example Usage#

1. Standard Constructor (Manages Lifecycle)

SignalProvider<CounterSignal>(
  create: () => CounterSignal(0),
  child: const CounterDisplay(),
)

2. Value Constructor (Exposes Existing Instance)

If the signal is created elsewhere (e.g. in a StatefulWidget's State or globally) and you want to expose it without managing its lifecycle or calling dispose, use SignalProvider.value: 

SignalProvider<CounterSignal>.value(
  value: myCounterSignal,
  child: const CounterDisplay(),
)

3. Multi-Providing Multiple Signals

Wrap multiple providers in a flat list to avoid deeply nested trees using SignalProvider.multi: 

SignalProvider.multi(
  providers: [
    SignalProvider<Counter>(create: () => Counter()),
    SignalProvider<User>(create: () => User()),
  ],
  child: const MyApp(),
)

Members of SignalProvider#

Member Type Signature Description
SignalProvider constructor dart SignalProvider({super.key, required T Function() create, this.child, this.dispose}) Creates a SignalProvider that manages the lifecycle of a created signal.
SignalProvider.value constructor dart SignalProvider.value({super.key, required T value, this.child}) Exposes an existing signal value to the widget tree.
SignalProvider._ constructor dart SignalProvider._({super.key, required T Function()? create, required T? value, required this.child, required this.dispose}) Private constructor for internal cloning and subclass usage.
child field dart Widget? child The widget subtree that will have access to the signal.
dispose field dart void Function(T)? dispose An optional custom dispose callback.
SignalProvider.multi constructor dart SignalProvider.multi({Key? key, required List providers, required Widget child}) Creates a SignalProvider that wraps multiple other SignalProvider s.
copyWith method dart SignalProvider copyWith(Widget child) Returns a clone of this SignalProvider with a new child widget.
createState method dart State<SignalProvider> createState()
providerOf method dart static SignalProvider? providerOf(BuildContext context, {bool listen = true}) Retrieves the SignalProvider widget itself from the ancestor path.
of method dart static T? of(BuildContext context, {bool listen = true}) Retrieves the reactive signal instance of type T directly from the nearest SignalProvider .

References#

The SignalProvider type is referenced and used in the following pages: