Why do I get `kotlin.native.concurrent.InvalidMutabilityException` [called from iOS] in the `init()`...

# multiplatform

[Andy Victors]

Why do I get kotlin.native.concurrent.InvalidMutabilityException [called from iOS] in the init() method by setting the value?
During init() the object should not be frozen, right? (confirmed by println in code).

var value: Float
    init {
        println("MetricReference:init (${metric.name} ): Frozen? -> ${this.isFrozen()} ")
        this.metric = metric
        this.metric.addObserver(this)
        this.value = metric.getValue()
    }

[ribesg]

I don’t see any problem in this code, it should work I think. I don’t know when the object is supposed to be frozen though

[Andy Victors]

Apparently the object becomes frozen after addObserver() line. Could someone from Kotlin authors explain what mechanism is taking place here?

[Andy Victors]

Wait, sorry. I know the answer - in addObserver() current objet is added to the frozenCopyOnWriteList<> from Stately library. I have already asked lib author to explain this behaviour.

[basher]

You can call ensureNeverFrozen() on an object you expect to never be frozen, and then you’ll get an exception with a trace that shows where it’s being frozen