PrefItem<T> class

Represents a particular named value in a PrefsStorage.

The value property acts like a synchronous "cache", while real reading and writing is done asynchronously in background.

For a newly created object the value always returns null, since the data is not read yet.

Inheritance

Implemented types

Implementers

Constructors

PrefItem(PrefsStorage storage, String key, {T initFunc()?, CheckValueFunc<T?>? checkValue})

checkValue → CheckValueFunc<T?>?: An optional callback that will be called before changing the value or saving a new value to the storage.
final
hashCode → int: The hash code for this object.
no setterinherited
hasListeners → bool: Whether any listeners are currently registered.
no setterinherited
initialized → Future<PrefItem<T>>: Future completes when the object initialization completes. That means we have read value or NULL from the storage.
no setter
initializedValue → Future<T?>: Allows to wait when for the first value being asynchronously read after object creation.
no setter
isDisposed → bool: Returns true after dispose was called.
no setter
isInitialized → bool: no setter
key → String: The current item key (or name, or id - depending on the storage).
final
runtimeType → Type: A representation of the runtime type of the object.
no setterinherited
storage → PrefsStorage: The parent storage containing the current item.
final
value ↔ T?: The current value stored in this notifier.
getter/setter pairoverride

addListener(VoidCallback listener) → void: Register a closure to be called when the object changes.
inherited
adjust(AdjustFunc f) → Future<T?>: Reads an existing value, computes a new one with AdjustFunc and writes the new value to the storage.
defined() → Future<bool>: Returns TRUE if we have the value in storage, otherwise FALSE.
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).
override
noSuchMethod(Invocation invocation) → dynamic: Invoked when a nonexistent method or property is accessed.
inherited
notifyListeners() → void: Call all the registered listeners.
inherited
read() → Future<T?>: Reads and returns the data from storage. value property will also be updated.
removeListener(VoidCallback listener) → void: Remove a previously registered closure from the list of closures that are notified when the object changes.
inherited
toString() → String: A string representation of this object.
inherited
toWaitList(List<Future> list) → void
write(T? value) → Future<void>