Hi; I’m trying to access the argument names of a f...

# reflect

[Ian Stewart]

Hi; I’m trying to access the argument names of a function as a KType. If I println the ktype, I get

(url: kotlin.String, cont: (result: kotlin.String) -> kotlin.Unit) -> kotlin.Unit

…so the information is there, at least internally. Is there any way of getting the ‘url’ and ‘cont’ strings out? I am able to get the types from the arguments() method.
I have read about using .reflect() to get a KFunction, but I cannot find a good example of how to do this. for myktype.classifier.reflect(), I get:

Unresolved reference. None of the following candidates is applicable because of receiver type mismatch:
public fun <R> Function<TypeVariable(R)>.reflect(): KFunction<TypeVariable(R)>? defined in kotlin.reflect.jvm

[diesieben07]

How are you obtaining this KType?

[Ian Stewart]

Hi Take; e.g.

import kotlin.reflect.full.declaredMemberFunctions
import kotlin.reflect.jvm.reflect

class MyClass {
    public fun callMe(cont: (result: String) -> Unit): Unit {
      cont("Hello")
    }
}

public fun main() {
  (MyClass::class).declaredMemberFunctions.forEach {
    val kTyped = it.parameters.get(1).type;
    println(kTyped)
  }
}

prints ‘(result: kotlin.String) -> kotlin.Unit’

[diesieben07]

kTyped.arguments[0].type?.findAnnotation<ParameterName>()?.name

Will obtain "result". The KType for a function will have type arguments ((String) -> Unit is really Function1<String, Unit> under the hood). Those type arguments can have a ParameterName annotation, if the name is known.

[diesieben07]

I.e. the actual type would be Function1<@ParameterName("result") String, Unit>.

[Ian Stewart]

Excellent, thank you, works perfectly.