ComputeOnce<V> class

Lazily computes a value at most once and caches either the result or error.

The computation may be synchronous or asynchronous. Subsequent calls return the cached value, rethrow the cached error, or await the in-flight Future.

If resolve is true, the computation is started eagerly.

Constructors

ComputeOnce(ComputeCall<V> call, {PosComputeCall<V>? posCompute, bool resolve = true})

Creates a ComputeOnce wrapping _call.

Properties

className → String

The class name of this compute implementation.

no setter

error → ({Object error, StackTrace stackTrace})?

Returns the cached error and stack trace if resolution failed, otherwise null.

no setter

hasError → bool

Whether the cached result is an error.

no setter

hashCode → int

The hash code for this object.

no setter, inherited

isResolved → bool

Whether the computation has completed (with value or error).

no setter

isResolving → bool

Whether the computation is currently in progress and not yet resolved.

no setter

posCompute ↔ PosComputeCall<V>?

Optional callback invoked after the computation completes.

getter/setter pair

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

value → V?

Returns the cached value if already resolved, otherwise null.

no setter

Methods

noSuchMethod(Invocation invocation) → dynamic

Invoked when a nonexistent method or property is accessed.

inherited

onCompute(V? value, Object? error, StackTrace? stackTrace) → void

Callback invoked when the computation completes.

resolve({bool throwError = true, FutureOr<V> onError(Object error, StackTrace stackTrace)?, V? onErrorValue}) → FutureOr<V>

Resolves the computation and returns its value (V) or a Future<V>.

resolveAsync({bool throwError = true, Future<V> onError(Object error, StackTrace stackTrace)?, V? onErrorValue}) → Future<V>

Resolves the computation asynchronously.

then<R>(FutureOr<R> onValue(V value), {Function? onError}) → Future<R>

Chains a callback to the resolved value.

toString() → String

A string representation of this object.

override

whenComplete(FutureOr<void> action()) → Future<V>

Registers a callback to be executed when resolution completes, regardless of success or failure.

whenResolved<R>(FutureOr<R> onResolve(V? value, Object? error, StackTrace? stackTrace)) → Future<R>

Invokes a callback when this value resolves, either successfully or with an error, and maps the outcome to a new result.

Operators

operator ==(Object other) → bool

The equality operator.

inherited