I have a function like this at top-level of a Kotl...

# getting-started

[Mikael Ståldal]

I have a function like this at top-level of a Kotlin file:

package mypackage

fun main(args: Array<String>) {
    // ...
}

Usually used as program entrypoint in JVM.

However, when I try to call it from another Kotlin module:

import mypackage.main

class MyClass {
    fun myMethod() {
        main(arrayOf("foo", "bar"))
    }
}

I get this strange error:

Kotlin: Overload resolution ambiguity: 
public fun main(args: Array<String>): Unit defined in mypackage
public fun main(args: Array<String>): Unit defined in mypackage

[Mikael Ståldal]

Ah, I think I found the reason, there are two files with a main fun defined in the same package. That's not a problem when running the programs, since then end up in different JVM classes (with Kt suffix). And not a problem when calling from Java. But how can I call from Kotlin?

[Joffrey]

Maybe resolve the ambiguity in your declarations, for example give them different names, and if you really need entrypoints, add main() functions that call those.

[Mikael Ståldal]

The problem is that I do not control the code of the library I am calling.

[Joffrey]

But why would a library have main() functions?

[Mikael Ståldal]

Since it is primarily used as CLI, and I am misusing it as a library.

[Mikael Ståldal]

Anyway, I just want to know if there is any reasonable workaround without changing the "library" I try to call.

[Mikael Ståldal]

One workaround would be to introduce a small bridge in Java, another would be to use reflection. I don't like either of those.

[Joffrey]

Another option would be to directly call the classes that the main function of the library calls (essentially inclining main).

[Joffrey]

Yet another one would be to call the CLI as a separate process from Kotlin using ProcessBuilder (this would be the "proper way" to use the CLI application)

[Mikael Ståldal]

The problem is that the main methods use private methods, so I cannot inline it. 🤷