Metronome class

A stream of DateTime events at intervals centered on anchor.

This stream accounts for drift but only guarantees that events are delivered on or after the interval. If the system is busy for longer than two intervals, only one will be delivered.

anchor defaults to Clock.now, which means the stream represents a self-correcting periodic timer. If anchor is the epoch, then the stream is synchronized to wall-clock time. It can be anchored anywhere in time, but this does not delay the first delivery.

Examples:

new Metronome.epoch(aMinute).listen((d) => print(d));

Could print the following stream of events, anchored by epoch, till the stream is canceled:

2014-05-04 14:06:00.001
2014-05-04 14:07:00.000
2014-05-04 14:08:00.003
...

Example anchored in the future (now = 2014-05-05 20:06:00.123)

new Metronome.periodic(aMillisecond * 100,
        anchor: DateTime.parse("2014-05-05 21:07:00"))
    .listen(print);

2014-05-04 20:06:00.223
2014-05-04 20:06:00.324
2014-05-04 20:06:00.423
...
Inheritance

Constructors

Metronome.epoch(Duration interval, {Clock clock = const Clock()})
Metronome.periodic(Duration interval, {Clock clock = const Clock(), DateTime? anchor})

Properties

anchor → DateTime?
final
clock → Clock
final
first → Future<DateTime>
The first element of this stream.
no setterinherited
hashCode → int
The hash code for this object.
no setterinherited
interval → Duration
final
isBroadcast → bool
Whether this stream is a broadcast stream.
no setteroverride
isEmpty → Future<bool>
Whether this stream contains any elements.
no setterinherited
last → Future<DateTime>
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<DateTime>
The single element of this stream.
no setterinherited

Methods

any(bool test(DateTime element)) → Future<bool>
Checks whether test accepts any element provided by this stream.
inherited
asBroadcastStream({void onListen(StreamSubscription<DateTime> subscription)?, void onCancel(StreamSubscription<DateTime> subscription)?}) → Stream<DateTime>
Returns a multi-subscription stream that produces the same events as this.
inherited
asyncExpand<E>(Stream<E>? convert(DateTime event)) → Stream<E>
Transforms each element into a sequence of asynchronous events.
inherited
asyncMap<E>(FutureOr<E> convert(DateTime 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
distinct([bool equals(DateTime previous, DateTime next)?]) → Stream<DateTime>
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<DateTime>
Returns the value of the indexth data event of this stream.
inherited
every(bool test(DateTime element)) → Future<bool>
Checks whether test accepts all elements provided by this stream.
inherited
expand<S>(Iterable<S> convert(DateTime element)) → Stream<S>
Transforms each element of this stream into a sequence of elements.
inherited
firstWhere(bool test(DateTime element), {DateTime orElse()?}) → Future<DateTime>
Finds the first element of this stream matching test.
inherited
fold<S>(S initialValue, S combine(S previous, DateTime element)) → Future<S>
Combines a sequence of values by repeatedly applying combine.
inherited
forEach(void action(DateTime element)) → Future<void>
Executes action on each element of this stream.
inherited
handleError(Function onError, {bool test(dynamic error)?}) → Stream<DateTime>
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(DateTime element), {DateTime orElse()?}) → Future<DateTime>
Finds the last element in this stream matching test.
inherited
listen(void onData(DateTime event)?, {Function? onError, void onDone()?, bool? cancelOnError}) → StreamSubscription<DateTime>
Adds a subscription to this stream.
override
map<S>(S convert(DateTime event)) → Stream<S>
Transforms each element of this stream into a new stream event.
inherited
noSuchMethod(Invocation invocation) → dynamic
Invoked when a nonexistent method or property is accessed.
inherited
pipe(StreamConsumer<DateTime> streamConsumer) → Future
Pipes the events of this stream into streamConsumer.
inherited
reduce(DateTime combine(DateTime previous, DateTime element)) → Future<DateTime>
Combines a sequence of values by repeatedly applying combine.
inherited
singleWhere(bool test(DateTime element), {DateTime orElse()?}) → Future<DateTime>
Finds the single element in this stream matching test.
inherited
skip(int count) → Stream<DateTime>
Skips the first count data events from this stream.
inherited
skipWhile(bool test(DateTime element)) → Stream<DateTime>
Skip data events from this stream while they are matched by test.
inherited
take(int count) → Stream<DateTime>
Provides at most the first count data events of this stream.
inherited
takeWhile(bool test(DateTime element)) → Stream<DateTime>
Forwards data events while test is successful.
inherited
timeout(Duration timeLimit, {void onTimeout(EventSink<DateTime> sink)?}) → Stream<DateTime>
Creates a new stream with the same events as this stream.
inherited
toList() → Future<List<DateTime>>
Collects all elements of this stream in a List.
inherited
toSet() → Future<Set<DateTime>>
Collects the data of this stream in a Set.
inherited
toString() → String
A string representation of this object.
inherited
transform<S>(StreamTransformer<DateTime, S> streamTransformer) → Stream<S>
Applies streamTransformer to this stream.
inherited
where(bool test(DateTime event)) → Stream<DateTime>
Creates a new stream from this stream that discards some elements.
inherited

Operators

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