DeferStream<T> class

The defer factory waits until a listener subscribes to it, and then it creates a Stream with the given factory function.

In some circumstances, waiting until the last minute (that is, until subscription time) to generate the Stream can ensure that listeners receive the freshest data.

By default, DeferStreams are single-subscription. However, it's possible to make them reusable.

Example

DeferStream(() => Stream.value(1)).listen(print); //prints 1
Inheritance
Available extensions

Constructors

DeferStream(Stream<T> streamFactory(), {bool reusable = false})
Constructs a Stream lazily, at the moment of subscription, using the streamFactory

Properties

first → Future<T>
The first element of this stream.
no setterinherited
hashCode → int
The hash code for this object.
no setterinherited
isBroadcast → bool
Whether this stream is a broadcast stream.
no setteroverride
isEmpty → Future<bool>
Whether this stream contains any elements.
no setterinherited
last → Future<T>
The last element of this stream.
no setterinherited
length → Future<int>
The number of elements in this stream.
no setterinherited
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited
single → Future<T>
The single element of this stream.
no setterinherited

Methods

any(bool test(T element)) → Future<bool>
Checks whether test accepts any element provided by this stream.
inherited
asBroadcastStream({void onListen(StreamSubscription<T> subscription)?, void onCancel(StreamSubscription<T> subscription)?}) → Stream<T>
Returns a multi-subscription stream that produces the same events as this.
inherited
asyncExpand<E>(Stream<E>? convert(T event)) → Stream<E>
Transforms each element into a sequence of asynchronous events.
inherited
asyncMap<E>(FutureOr<E> convert(T event)) → Stream<E>
Creates a new stream with each data event of this stream asynchronously mapped to a new event.
inherited
cast<R>() → Stream<R>
Adapt this stream to be a Stream<R>.
inherited
contains(Object? needle) → Future<bool>
Returns whether needle occurs in the elements provided by this stream.
inherited
debounce(Stream window(T event)) → Stream<T>

Available on Stream<T>, provided by the DebounceExtensions extension

Transforms a Stream so that will only emit items from the source sequence if a window has completed, without the source sequence emitting another item.
debounceTime(Duration duration) → Stream<T>

Available on Stream<T>, provided by the DebounceExtensions extension

Transforms a Stream so that will only emit items from the source sequence whenever the time span defined by duration passes, without the source sequence emitting another item.
distinct([bool equals(T previous, T next)?]) → Stream<T>
Skips data events if they are equal to the previous data event.
inherited
drain<E>([E? futureValue]) → Future<E>
Discards all data on this stream, but signals when it is done or an error occurred.
inherited
elementAt(int index) → Future<T>
Returns the value of the indexth data event of this stream.
inherited
every(bool test(T element)) → Future<bool>
Checks whether test accepts all elements provided by this stream.
inherited
expand<S>(Iterable<S> convert(T element)) → Stream<S>
Transforms each element of this stream into a sequence of elements.
inherited
firstWhere(bool test(T element), {T orElse()?}) → Future<T>
Finds the first element of this stream matching test.
inherited
fold<S>(S initialValue, S combine(S previous, T element)) → Future<S>
Combines a sequence of values by repeatedly applying combine.
inherited
forEach(void action(T element)) → Future<void>
Executes action on each element of this stream.
inherited
handleError(Function onError, {bool test(dynamic error)?}) → Stream<T>
Creates a wrapper Stream that intercepts some errors from this stream.
inherited
join([String separator = ""]) → Future<String>
Combines the string representation of elements into a single string.
inherited
lastWhere(bool test(T element), {T orElse()?}) → Future<T>
Finds the last element in this stream matching test.
inherited
listen(void onData(T event)?, {Function? onError, void onDone()?, bool? cancelOnError}) → StreamSubscription<T>
Adds a subscription to this stream.
override
map<S>(S convert(T event)) → Stream<S>
Transforms each element of this stream into a new stream event.
inherited
mergeWith(Iterable<Stream<T>> streams) → Stream<T>

Available on Stream<T>, provided by the MergeExtension extension

Combines the items emitted by multiple streams into a single stream of items. The items are emitted in the order they are emitted by their sources.
noSuchMethod(Invocation invocation) → dynamic
Invoked when a nonexistent method or property is accessed.
inherited
pipe(StreamConsumer<T> streamConsumer) → Future
Pipes the events of this stream into streamConsumer.
inherited
reduce(T combine(T previous, T element)) → Future<T>
Combines a sequence of values by repeatedly applying combine.
inherited
singleWhere(bool test(T element), {T orElse()?}) → Future<T>
Finds the single element in this stream matching test.
inherited
skip(int count) → Stream<T>
Skips the first count data events from this stream.
inherited
skipWhile(bool test(T element)) → Stream<T>
Skip data events from this stream while they are matched by test.
inherited
startWith(T startValue) → Stream<T>

Available on Stream<T>, provided by the StartWithExtension extension

Prepends a value to the source Stream.
switchMap<S>(Stream<S> mapper(T value)) → Stream<S>

Available on Stream<T>, provided by the SwitchMapExtension extension

Converts each emitted item into a Stream using the given mapper function. The newly created Stream will be be listened to and begin emitting items, and any previously created Stream will stop emitting.
take(int count) → Stream<T>
Provides at most the first count data events of this stream.
inherited
takeWhile(bool test(T element)) → Stream<T>
Forwards data events while test is successful.
inherited
timeout(Duration timeLimit, {void onTimeout(EventSink<T> sink)?}) → Stream<T>
Creates a new stream with the same events as this stream.
inherited
toList() → Future<List<T>>
Collects all elements of this stream in a List.
inherited
toSet() → Future<Set<T>>
Collects the data of this stream in a Set.
inherited
toString() → String
A string representation of this object.
inherited
transform<S>(StreamTransformer<T, S> streamTransformer) → Stream<S>
Applies streamTransformer to this stream.
inherited
where(bool test(T event)) → Stream<T>
Creates a new stream from this stream that discards some elements.
inherited

Operators

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