Watcher class

A Widget that automatically tracks Property access and rebuilds when they change.

The Watcher is the primary way to consume state in Frost. It uses a smart tracking system that detects which properties are accessed within the watch builder and subscribes to them.

Basic Usage

final count = 0.property;

Watcher(
  watch: (context) => Text("Count: ${count.value}"),
)

Lifecycle & Manual Signals

Watcher can replace StatefulWidget for simple lifecycle needs or explicit signal listening.

Watcher(
  onInit: acquireSomeController,
  onDispose: releaseController,
  signal: myCustomSignal, // Rebuilds when this signal emits
  signals: {signal1, signal2} // More than one signal can be connected if needed.
  watch: (context) => const Text("Signal(s) emitted! Using some controller as well."),
)

Inheritance

Constructors

Watcher({Key? key, Property? property, Set<Property>? properties, Signal? signal, Set<Signal>? signals, required Widget watch(BuildContext context), bool when()?, VoidCallback? onActivate, VoidCallback? onDeactivate, VoidCallback? onInit, VoidCallback? onDispose}): const

Properties

hashCode → int: The hash code for this object.
no setterinherited
key → Key?: Controls how one widget replaces another widget in the tree.
finalinherited
onActivate → VoidCallback?: A callback which is called when this widget is reinserted into the tree after having been removed via deactivate method of the state object of this widget.
final
onDeactivate → VoidCallback?: A callback which is called when the deactivate method of this widget's state is called.
final
onDispose → VoidCallback?: A callback which does some work when the widget is disposed.
final
onInit → VoidCallback?: A callback which does some work when the widget is created.
final
properties → Set<Property>?: Optional Field for connecting to multiple properties.
final
property → Property?: Optional property that when changed rebuilds the widget. Use when connecting only one property.
final
runtimeType → Type: A representation of the runtime type of the object.
no setterinherited
signal → Signal?: Optional signal that when emitted rebuilds the widget. Use when connecting only one signal.
final
signals → Set<Signal>?: Optional Field for connecting to multiple signals.
final
watch → Widget Function(BuildContext context): The builder for the widget that uses property inside itself.
final
when → bool Function()?: Optional function that makes the watcher rebuild only when it returns true
final

Methods

createElement() → StatefulElement: Creates a StatefulElement to manage this widget's location in the tree.
inherited
createState() → State<Watcher>: Creates the mutable state for this widget at a given location in the tree.
override
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, int wrapWidth = 65}) → 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