How do I initialise a variable inside an Object cl...

# kotlin-native

[galex]

How do I initialise a variable inside an Object class that I need before doing requests? For doing the following:

AnalyticsConfig.init().baseUrl = "<http://192.168.85.16:8000>"

I get the following error:

Uncaught Kotlin exception: kotlin.native.concurrent.InvalidMutabilityException: mutation attempt of frozen com.analytics.core.helper.AnalyticsConfig@94d888

[Ellen Shapiro]

If anyone has a better answer i’d love to hear it but the only way I found to work was to make something a class rather than an object

[Ellen Shapiro]

The way the memory graph freezes global objects is pretty brutal

[galex]

No singletons ever because of Kotlin/Native? That sucks 😢

[Ellen Shapiro]

I mean, like i said, i hope there’s a better answer than this

[galex]

Hope so too!

[Ellen Shapiro]

it’s mostly a problem when you’re modifying hte properties of the singleton

[Ellen Shapiro]

if you have the singleton as a wrapper for some kind of I/O or something it seems like it’s fine, because it’s not modifying its own properties

[Ellen Shapiro]

(although protip, don’t do that with a ktor client as a property because it doesn’t work at all)

[olonho]

In your case just set it in constructor of the singleton

[galex]

But constructors are not allowed for objects

[svyatoslav.scherbina]

Consider using https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.native.concurrent/-atomic-reference/index.html to hold baseUrl value.

[galex]

Interesting! The only thing is that I set up this Object in a common module, so I do not have access to K/N APIs

[svyatoslav.scherbina]

`expect`/`actual` feature is designed to solve this problem too.

[galex]

Yeah but it’s not a value I would like to have hardcorded in the common code or a platform, this baseUrl is something I’d like to set up at runtime from apps using their platform libraries

[Ellen Shapiro]

For something similar, I wound up passing in an interface

[olonho]

I am talking init block

[Ellen Shapiro]

i think you might still have the problem of mutating something frozen if you hang on to the object

[olonho]

Or indeed as Slava suggested, use atomic reference

[Ellen Shapiro]

(this is what I did fwiw, SecureStorage is an interface I implemented in each app: https://github.com/bakkenbaeck/PorchPirateProtector/blob/master/code/PPPShared/src/commonMain/kotlin/manager/TokenManager.kt#L8)

[galex]

Yeah I am trying to avoid to have to send what I need configured once in every function

[galex]

I am porting this analytics feature from an App to KMP and wanted to really have 1-1 same API

[Ellen Shapiro]

Yeah…I think i tried just hanging on to the object but was still getting the frozen thing. @olonho are you suggesting something like:

object Thing {
   init { // set up here }
}

[Ellen Shapiro]

if so, how would you pass in the information you’re trying to set up?

[olonho]

in case above it’s just calling top-level function, and see https://github.com/JetBrains/kotlin-native/blob/master/samples/tetris/src/tetrisMain/kotlin/Config.kt#L11 for solving similar problem in generic way

[galex]

hmmm… I have a hard time understanding how to pass a value to a Singleton written in the commonMain sourceset and how to use it from Kotlin/Native mainly (it is trivial to use in JVM and JS)…

[galex]

If only Objects had constructors… 🙏

[Ellen Shapiro]

the Extremely Stupid Workaround part of my brain says “Make a wrapper class in your iosMain which can be instantiated and have that pass the value from Swift”

[Ellen Shapiro]

have not tried this though so i cannot reasonably recommend it

[galex]

There’s this, not sure it is applicable to KMP thought https://medium.com/@BladeCoder/kotlin-singletons-with-argument-194ef06edd9e

[galex]

Plus this is made for companion objects, not pure Objects

[galex]

We could pass a lambda which returns our configured value (in my case a String) in the same fashion, I think. Going to try that -> Doesn’t work.