LxComputed<T> class

A value derived from other reactive objects.

LxComputed automatically tracks its dependencies and re-evaluates when they change. Calculations are lazy and memoized.

// Example usage:

final firstName = 'John'.lx;
final lastName = 'Doe'.lx;

// Updates only when firstName or lastName changes
final fullName = LxComputed(() => '${firstName()} ${lastName()}');

Inheritance

Available extensions

Constructors

LxComputed(T _compute(), {bool equals(T previous, T current)?, bool staticDeps = false, bool eager = false, String? name}): Creates a synchronous computed value.

Properties

computedValue → T: Available on LxReactive<LxStatus<T>>, provided by the LxStatusReactiveExtensions extension
Alias for requireValue.
no setter
equals → bool Function(T previous, T current)?: Custom equality function. When null, uses ==.
finalinherited
errorOrNull → Object?: Available on LxReactive<LxStatus<T>>, provided by the LxStatusReactiveExtensions extension
Returns the current error if the status is LxError, otherwise null.
no setter
graphDepth ↔ int: Returns the current depth in the dependency graph.
getter/setter pairinherited
hashCode → int: The hash code for this object.
no setterinherited
hasListener → bool: Whether there are active listeners.
no setterinherited
hasValue → bool: Available on LxReactive<LxStatus<T>>, provided by the LxStatusReactiveExtensions extension
Alias for isSuccess.
no setter
id → int: A unique runtime identifier for this reactive instance.
finalinherited
isDisposed → bool: Whether the reactive object has been closed/disposed.
no setterinherited
isError → bool: Available on LxReactive<LxStatus<T>>, provided by the LxStatusReactiveExtensions extension
Returns true if the status is LxError.
no setter
isIdle → bool: Available on LxReactive<LxStatus<T>>, provided by the LxStatusReactiveExtensions extension
Returns true if the status is LxIdle.
no setter
isLoading → bool: Available on LxReactive<LxStatus<T>>, provided by the LxStatusReactiveExtensions extension
Alias for isWaiting.
no setter
isSensitive ↔ bool: Whether this reactive object contains sensitive data.
getter/setter pairinherited
isSuccess → bool: Available on LxReactive<LxStatus<T>>, provided by the LxStatusReactiveExtensions extension
Returns true if the status is LxSuccess.
no setter
isWaiting → bool: Available on LxReactive<LxStatus<T>>, provided by the LxStatusReactiveExtensions extension
Returns true if the status is LxWaiting.
no setter
lastValue → T?: Available on LxReactive<LxStatus<T>>, provided by the LxStatusReactiveExtensions extension
Returns the LxStatus.lastValue (the most recent successful value).
no setter
name ↔ String?: An optional descriptive name for debugging and profiling.
getter/setter pairinherited
onCancel → void Function()?: Called when the stream is cancelled.
finalinherited
onListen → void Function()?: Called when the stream is listened to.
finalinherited
ownerId ↔ String?: The registration key of the owning controller, if applicable.
getter/setter pairinherited
requireValue → T: Available on LxReactive<LxStatus<T>>, provided by the LxStatusReactiveExtensions extension
Force-retrieves the current value if the status is LxSuccess.
no setter
runtimeType → Type: A representation of the runtime type of the object.
no setterinherited
stackTraceOrNull → StackTrace?: Available on LxReactive<LxStatus<T>>, provided by the LxStatusReactiveExtensions extension
Returns the stack trace if the status is LxError, otherwise null.
no setter
stream → Stream<T>: A Stream that emits the latest value whenever it updates.
no setterinherited
value → T: The current state of the reactive object.
no setteroverride
valueOrNull → T?: Available on LxReactive<LxStatus<T>>, provided by the LxStatusReactiveExtensions extension
Returns the current value if the status is LxSuccess, otherwise null.
no setter
wait → Future<T>: Available on LxReactive<LxStatus<T>>, provided by the LxStatusReactiveExtensions extension
Returns a Future that completes when the operation reaches a terminal state.
no setter

Methods

addListener(void listener()) → void: Adds a listener.
inherited
call() → T: Functor-like call to get value.
inherited
close() → void: Permanently closes the reactive object and releases all internal resources.
inherited
dispose() → void: Disposes the notifier.
inherited
listen(void callback(T value)) → LxWorker<T>: Available on LxReactive<T>, provided by the LxReactiveWatchExtensions extension
Attaches a listener to this reactive value.
listen(void onSuccess(T value), {void onIdle()?, void onWaiting()?, void onError(Object error)?, dynamic onProcessingError(Object error, StackTrace stackTrace)?}) → LxWorker<LxStatus<T>>: Available on LxReactive<LxStatus<T>>, provided by the LxStatusReactiveExtensions extension
Specialized listen for async status that allows handling individual states.
maybeNotifyGraphChange(Iterable<LxReactive> reactives) → void: Notifies observers of a graph change only if the dependencies have actually changed.
inherited
named(String name) → R: Available on R, provided by the LxNamingExtension extension
assigns a debug name to this reactive object.
noSuchMethod(Invocation invocation) → dynamic: Invoked when a nonexistent method or property is accessed.
inherited
notify() → void: Alias for refresh.
inherited
refresh() → void: Triggers a notification without changing the value.
override
register(String ownerId) → R: Available on R, provided by the LxNamingExtension extension
Links this reactive object to an owner ID.
removeListener(void listener()) → void: Removes a listener.
inherited
select<R>(R selector(T value)) → LxComputed<R>: Creates a specific selection of the state that only updates when the selected value changes.
inherited
sensitive() → R: Available on R, provided by the LxNamingExtension extension
Marks this object as containing sensitive data (redacted in logs).
toString() → String: A string representation of this object.
override
transform<R>(Stream<R> transformer(Stream<T> stream)) → LxStream<R>: inherited

Operators

operator ==(Object other) → bool: The equality operator.
inherited

Static Methods

async<T>(Future<T> compute(), {bool equals(T previous, T current)?, bool showWaiting = false, bool staticDeps = false, T? initial, String? name, LxAsyncConcurrency concurrency = LxAsyncConcurrency.latest}) → LxAsyncComputed<T>: Creates an asynchronous computed value.
deferred<T>(T compute(), {bool equals(T previous, T current)?, bool showWaiting = false, bool staticDeps = false, T? initial, String? name, LxAsyncConcurrency concurrency = LxAsyncConcurrency.latest}) → LxAsyncComputed<T>: Creates a deferred computation that runs in a microtask and returns LxStatus.