Can t function references specify type parameters kotlinlang #announcements

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raulraja

09/26/2017, 6:08 PM

Can't function references specify type parameters?

diesieben07

09/26/2017, 6:52 PM

If I understand you correctly, no. Please clarify what exactly you mean though.

alexcouch

09/26/2017, 6:56 PM

So like java lambdas? Where you have a method reference and you don't call the parameters because the runtime fills in the parameters for you?

lambdaCall(LambdaClass::methodReference)

like that. Cause really, this works because the runtimes fills in the correct arguments based on the method/function the method is being referenced from (right?) so ideally in kotlin, I would assume that a function reference is the same thing since kotlin uses the terms "function" and "member functions" so when I hear "function references" I think of method references in java. Which I would assume the answer to be no, but I could be wrong

raulraja

09/26/2017, 7:10 PM

::myfunc<A>

Say I have a function with a type like this:

inline fun <reified A> myfunc(): String = 
   A::class.java.simpleName

how do you lift that to a method reference since the type args can't be inferred from the function arguments?

Works:

fun myfunc2(): String = ""
val y = ::myfunc2

Does not work:

inline fun <reified A> myfunc(): String =
        A::class.java.simpleName
val x = ::myfunc<Int>

diesieben07

09/26/2017, 7:42 PM

You cannot. You can't inline into a method reference as far as I know. You need to use a normal lambda

raulraja

09/26/2017, 7:49 PM

ok, same issue when not

inline

though

diesieben07

09/26/2017, 7:49 PM

Yes, you can't specify the type parameter like that, you need a lambda

raulraja

09/26/2017, 7:50 PM

👍

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