CachedWatcher<T> class abstract

CachedWatcher

A specialized version of Watcher that adds local caching capabilities. Ideal for use cases where persistent state management is required, such as saving user preferences, caching network responses, or maintaining temporary state across app restarts.

The CachedWatcher extends Watcher and inherits its reactive state management capabilities, while adding the functionality to automatically write to and read from a local cache.

CachedWatcher is designed to be extended for various data types, with abstract read and write methods that need to be implemented in subclasses. This design allows for flexible and type-specific serialization and deserialization strategies for cached data.

Usage: To use CachedWatcher, create a subclass for the specific data type you wish to cache. Implement the read and write methods to define how data is serialized and deserialized.

Example Subclass Implementation:

class StringCachedWatcher extends CachedWatcher<String> {
  StringCachedWatcher(String initialValue, String key) : super(initialValue, key: key);

  @override
  String? read(dynamic data) => data as String;

  @override
  dynamic write(String value) => value;
}

Parameters:

• initialValue: The starting value for the watcher.
• key: A unique string key used for storing and retrieving the cached data.

Abstract Methods:

• read: An abstract method that should be implemented to define how the stored data is read and converted back into the expected type.
• write: An abstract method that should be implemented to define how the state is serialized and stored in the local cache.

Additional Methods:

• startCaching: Enables caching of the watcher's value.
• stopCaching: Disables caching of the watcher's value.
• deleteCache: Clears the cache for this specific CachedWatcher.
• deleteAllCaches: Static method to clear all caches associated with CachedWatcher.

Inheritance

• Object
• ChangeNotifier
• Watcher<T>
• CachedWatcher

Implementers

• BaseListCachedWatcher
• BaseMapCachedWatcher
• BaseSetCachedWatcher
• BoolCachedWatcher
• ColorCachedWatcher
• DateTimeCachedWatcher
• DoubleCachedWatcher
• DurationCachedWatcher
• IntCachedWatcher
• NumCachedWatcher
• StringCachedWatcher
• UriCachedWatcher

Available Extensions

• WatcherListenableExtension
• WatcherValueListenableExtension

Constructors

CachedWatcher(T initialValue, {String? key})

Properties

cache → Future

no setter

hashCode → int

The hash code for this object.

no setter, inherited

hasListeners → bool

Whether any listeners are currently registered.

no setter, inherited

initialValue → T

final

isCaching → bool

isCaching

no setter

isDisposed → bool

Flag which returns true if you called the dispose method. It is useful when you want to safely do some operations on the Watcher without getting an exception if it gets disposed.

no setter, inherited

key ↔ String

key

late, final

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

safeMode → bool

safeMode if enabled will not allow any setting of value or notifying any listeners if the Watcher isDisposed

final, inherited

stream → Stream<T>

Converts the Watcher into a Stream. This stream emits values whenever the value changes. The use of distinct ensures that consecutive duplicate values are filtered out, thus the stream only emits when the value actually changes.

no setter, inherited

v ↔ T

Equivalent to the getter value but in shorter syntax.

getter/setter pair, inherited-getter, override-setter

value ↔ T

The current value stored in this watcher.

getter/setter pair, inherited-getter, override-setter

Methods

addListener(VoidCallback listener) → void

Register a closure to be called when the object changes.

inherited

debounce(Duration duration, void action(T value)) → VoidCallback

Registers a debounced callback which is invoked only after the notifier's value is stable for the specified duration.

inherited

deleteCache() → Future<void>

deleteCache

dispose() → void

Discards any resources used by the object. After this is called, the object is not in a usable state and should be discarded (calls to addListener will throw after the object is disposed).

inherited

noSuchMethod(Invocation invocation) → dynamic

Invoked when a nonexistent method or property is accessed.

inherited

notifyListeners() → void

Call all the registered listeners.

inherited

onChange(void action(T value)) → VoidCallback

Registers a callback to be invoked whenever the ValueNotifier's value changes.

inherited

read(dynamic data) → FutureOr<T?>

read

refresh() → void

Rebuilds and trigger any listeners of any WatchValue or watch attached to that Watcher.

inherited

removeListener(VoidCallback listener) → void

Remove a previously registered closure from the list of closures that are notified when the object changes.

inherited

setWithoutNotify(T newValue) → void

inherited

startCaching() → void

startCaching

stopCaching() → void

stopCaching

toString() → String

A string representation of this object.

inherited

updateIf(bool condition(T), T newValue) → void

Updates the ValueNotifier's value to newValue if condition returns true.

inherited

updateOnAction<R>(R action()) → R

Will notifyListeners after a specific action has been made, and optionally return a result R of certain type.

inherited

write(T value) → FutureOr

write

Operators

operator ==(Object other) → bool

The equality operator.

inherited

Static Methods

deleteAllCaches() → Future<void>

deleteAllCaches