matchingStatus property
A stream of matching-status changes, or null if
AdvancedPublisherOptions.enableMatchingListener was not set when this
publisher was declared.
Emits true when the first matching subscriber connects and false when
the last one disconnects — canon's own wording is "if last subscriber
disconnects or when the first subscriber connects".
Lifetime. Canon binds this listener to the publisher: it runs
until the corresponding advanced publisher is dropped. The stream
therefore completes when close is called. Its behaviour when the
session is closed with this publisher still open is not part of this
contract; the same is true of AdvancedSubscriber.missEvents.
(Contrast AdvancedSubscriber.detectedPublishers, whose listener canon
binds to the session instead.)
Implementation
Stream<bool>? get matchingStatus => _matchingController?.stream;