Hey, I have no idea where to post this, but I am at a complete loss and cannot find anything online....

# getting-started

[Ilya P]

Hey, I have no idea where to post this, but I am at a complete loss and cannot find anything online. The issue is with log4j-2. There's a class for structured logging called MapMessage and it is possible to use from Java, but not from Kotlin.
So this java code works just fine and it is able to infer the type params of MapMessage (which are MapMessage<M extends MapMessage<M, V>, V> , so there is a self capture there)

Logger l = LogManager.getLogger();
 l.info(new MapMessage<>(Map.of("r", 1)));

While Kotlin code like this fails with Cannot infer type for this parameter. Please specify it explicitly. Which is impossible to do.

val logger = LogManager.getLogger()
 <http://logger.info|logger.info>(MapMessage(mapOf("key" to "value")))

Any help would be appreciated. I can use StringMapMessage as that binds the first parameter to be itself, but that is limiting.

[Youssef Shoaib [MOD]]

You could just use MapMesaage<*, _>(mapOf(...))

[Ilya P]

It is not allowed to use * there

[ephemient]

hack but

MapMessage<Nothing, _>(mapOf(...))

would work

[Ilya P]

It crashed the compiler

[ephemient]

hmm. works in a simple example here blob shrug

[Ilya P]

I'm on 2.0.20

[ephemient]

you could create a less tricky subtype

class KotlinMapMessage<V>(map: Map<String, V>) : MapMessage<KotlinMapMessage<V>, V>(map)

and use that instead

[ephemient]

ditto…

[Ilya P]

I think it crashes something in the gradle pipeline for me, huh

[Ilya P]

Also intellij

[Ilya P]

Yeah, I guess some wrapper like that should work

[Ilya P]

Or adapter, or whatever

[Ilya P]

It's just interesting if that is expected behaviour of Kotlin type inference?

[Ilya P]

I understand that the algorithms are not identical, but it's the first time in years I see something like this

[ephemient]

crashing isn't expected behavior, but it being stricter about M might be, I'm not sure

[Ilya P]

Well, crashing sure is not 😃

[Ilya P]

Thanks for helping btw