Object key
) Retrieves the zone-value associated with key
.
If this zone does not contain the value looks up the same key in the
parent zone. If the key
is not found returns null
.
Any object can be used as key, as long as it has compatible operator ==
and hashCode
implementations.
By controlling access to the key, a zone can grant or deny access to the
zone value.
Source
/**
* Retrieves the zone-value associated with [key].
*
* If this zone does not contain the value looks up the same key in the
* parent zone. If the [key] is not found returns `null`.
*
* Any object can be used as key, as long as it has compatible `operator ==`
* and `hashCode` implementations.
* By controlling access to the key, a zone can grant or deny access to the
* zone value.
*/
operator [](Object key);