operator [] method
The value for the given key
, or null
if key
is not in the map.
Some maps allow null
as a value.
For those maps, a lookup using this operator cannot distinguish between a
key not being in the map, and the key being there with a null
value.
Methods like containsKey or putIfAbsent can be used if the distinction
is important.
Implementation
@override
SunnyObservableMap<K, V>? operator [](Object? key) {
final k = key as K1?;
return putIfAbsent(key, () {
final map = SunnyObservableMap<K, V>(
diffDelegator: listDiffDelegator,
debugLabel: "$debugLabel[$key]",
);
addDisposer(map.changeStream.listen((changes) {
changeController.add(newBuilder()..change(k, map));
}).cancel);
return map;
});
}