does kotlin (jvm) have any kind of weak identity m...

# announcements

[David Glasser]

does kotlin (jvm) have any kind of weak identity map, or an equivalent feature (ie, to let my code effectively add a property to an arbitrary object)?
I know Java has WeakHashMap but I want the map to be based on identity, not hashCode.

[darkmoon_uk]

@David GlasserI don't think so; I used Guava MapMaker on my JVM MP target and NSMapTable for iOS to achieve this kind of flexibility.

[nfrankel]

if you want to add a property to a class
you can use extension properties
https://kotlinlang.org/docs/reference/extensions.html#extension-properties

[David Glasser]

That can't actually store any data

[nfrankel]

perhaps you could detail more what’s your requirement?

[Derek Peirce]

WeakHashMap is suggested to only be used on objects that already use identity for equivalence. Perhaps you should ensure that your intended keys use identity equality as well.

[ikej]

You're probably looking for ephermerons, unfortunately they do not exist on the JVM https://en.wikipedia.org/wiki/Ephemeron

[nfrankel]

i learned something
thanks @ikej

[jpg]

Best chance would be to roll something based on https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.native.ref/-weak-reference/index.html