SubState<T> class

Creates a variable and subscribes to it.

Whenever ValueNotifier.value updates, it will rebuild the builder. On the first call, it initializes ValueNotifier to initialData. initialData is ignored on subsequent calls.

The following example showcases a basic counter application:

class Counter extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return SubState(
      initialData: 0,
      builder: (context, counter) => GestureDetector(
        // automatically triggers a rebuild of the Counter widget
        onTap: () => counter.value++,
        child: Text(counter.value.toString()),
      ),
    );
  }
}

This is a Wrapper around SubValueNotifier with less parameters to ease a transition from React Hooks.

See also:

• ValueNotifier
• SubStreamController, an alternative to ValueNotifier for state.

Inheritance

• Object
• DiagnosticableTree
• Widget
• StatefulWidget
• SubValue<ValueNotifier<T>>
• SubDisposableListenable<ValueNotifier<T>>
• SubValueNotifier<T>
• SubState

Constructors

SubState({required T initialData, required SubValueBuild<ValueNotifier<T>> builder, SubValueKeys? keys})

Creates a variable and subscribes to it.

Properties

builder → SubValueBuild<ValueNotifier<T>>

Creates the child of this Widget with the value.

final, inherited

create → SubValueBuilderCreate<ValueNotifier<T>>

Creates the value. Called at least once and everytime keys changes.

final, inherited

dispose → SubValueBuilderDispose<ValueNotifier<T>>?

Disposes the value. Called before recreation and when disposing. Useful for Listeners, etc.

final, inherited

hashCode → int

The hash code for this object.

no setter, inherited

key → Key?

Controls how one widget replaces another widget in the tree.

final, inherited

keys → SubValueBuilderKeys?

Used to decide when to recreate the value. If null, the value is never recreated.

final, inherited

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

update → SubValueBuilderUpdate<ValueNotifier<T>>?

Updates the value. Called every build. If null, does nothing. In the call order, this comes after recreating the value.

final, inherited

Methods

createElement() → StatefulElement

Creates a StatefulElement to manage this widget's location in the tree.

inherited

createState() → State<SubValue<ValueNotifier<T>>>

Creates the mutable state for this widget at a given location in the tree.

inherited

debugDescribeChildren() → List<DiagnosticsNode>

Returns a list of DiagnosticsNode objects describing this node's children.

inherited

debugFillProperties(DiagnosticPropertiesBuilder properties) → void

Add additional properties associated with the node.

inherited

noSuchMethod(Invocation invocation) → dynamic

Invoked when a nonexistent method or property is accessed.

inherited

toDiagnosticsNode({String? name, DiagnosticsTreeStyle? style}) → DiagnosticsNode

Returns a debug representation of the object that is used by debugging tools and by DiagnosticsNode.toStringDeep.

inherited

toString({DiagnosticLevel minLevel = DiagnosticLevel.info}) → String

A string representation of this object.

inherited

toStringDeep({String prefixLineOne = '', String? prefixOtherLines, DiagnosticLevel minLevel = DiagnosticLevel.debug}) → String

Returns a string representation of this node and its descendants.

inherited

toStringShallow({String joiner = ', ', DiagnosticLevel minLevel = DiagnosticLevel.debug}) → String

Returns a one-line detailed description of the object.

inherited

toStringShort() → String

A short, textual description of this widget.

inherited

Operators

operator ==(Object other) → bool

The equality operator.

inherited