How to get the value for reified in Kotlin? - kotlin

Question

I am getting started with kotlin and stuck with an issue.
I have a request function as below :
fun dumRequest(): MyRequest {
val token = JwtTokenGenerator.createToken(user)
return MyRequest(token.serialize())
}
And this is being passed as an argument to a function as :
val response: ResponseEntity<MyRequest> = callMyRequest(dumRequest())
And callMyRequest() is of generic type as :
private inline fun <reified T, reified Y> callMyRequest(request: Y): ResponseEntity<T> {
val headers = HttpHeaders()
headers.add(CONTENT_TYPE, "application/json")
headers.add(AUTHORIZATION, request.token) // I want something like this here
// other business logic
}
I want to get the token from the request object which is being pass to callMyRequest() and set it in the AUTH header. But since this is a generic type, not sure how I can get the token field out of this ?
Any help would be highly appreciated.
TIA

Answer 1

I don't really think you need to make Y reified here. It would suffice to restrict it to an interface containing the token, and then letting MyRequest implement that interface. Like <Y : AuthenticatedRequest>.
Actually, you don't really need the Y type parameter at all, because you could just take the interface-type as a parameter directly.
Something like this:
interface AuthenticatedRequest {
val token: String
}
data class MyRequest(override val token: String) : AuthenticatedRequest
private inline fun <reified T> callMyRequest(request: AuthenticatedRequest): ResponseEntity<T> {
val headers = HttpHeaders()
headers.add(CONTENT_TYPE, "application/json")
headers.add(AUTHORIZATION, request.token) // I want something like this here
// other business logic
}
It's when you want to deserialize your result to T that the value of reified comes in handy. It might make you able to do something like response.readEntity<T>(), without having to deal with the class-objects directly.