In brief, how can one reference / iterate reflectively over overloaded top-level functions in Kotlin, such as kotlin.io.println
?
Given the following:
object Bar {
fun foo(x: Int) = Unit
fun foo(x: Byte) = Unit
fun foo(x: Float) = Unit
}
I can iterate over the various overloads of foo
by doing:
fun main() {
Bar::class.memberFunctions
.filter { kFunction -> kFunction.name == "foo" }
.forEach { kFunction -> println(kFunction) }
}
Which produces:
fun com.example.Bar.foo(kotlin.Byte): kotlin.Unit
fun com.example.Bar.foo(kotlin.Float): kotlin.Unit
fun com.example.Bar.foo(kotlin.Int): kotlin.Unit
However , if the various overloads of foo
are defined top-level ( outside of a class or object definition ) such as simply:
fun foo(x: Int) = Unit
fun foo(x: Byte) = Unit
fun foo(x: Float) = Unit
Then there doesn't seem to be a way to reference them.
I tried being tricky using a top-level function in my example ( such as main
) to access the synthetic class:
::main::class.memberFunctions
.filter { kFunction -> kFunction.name == "foo" }
.forEach { kFunction -> println(kFunction) }
But it pukes on the fact that it's synthetic:
Exception in thread "main" java.lang.UnsupportedOperationException: This class is an internal synthetic class generated by the Kotlin compiler, such as an anonymous class for a lambda, a SAM wrapper, a callable reference, etc. It's not a Kotlin class or interface, so the reflection library has no idea what declarations does it have. Please use Java reflection to inspect this class.
How can I reference top-level overloaded functions in Kotlin?
More specifically, top-level overloaded functions defined in other packages / modules such as kotlin.io.println
?
Top level functions by definition don't have a declaring class.
::println.javaClass.declaringClass //will return null
so you don't have a class to use reflection on, and consequently, you can't enumerate the top level members of a package.( Some magic can be done though, if you are willing to trade your soul )
The only way you can reference ambiguous top level functions is by helping the compiler to resolve the ambiguity like this:
val functionReference: (Int)->Unit = ::foo
and then you can call functionReference()
The technical post webpages of this site follow the CC BY-SA 4.0 protocol. If you need to reprint, please indicate the site URL or the original address.Any question please contact:yoyou2525@163.com.