is there any documentation on using the kotlin `List` type (and other types from the `collections` p...

# kotlin-native

[Michael Bryant]

is there any documentation on using the kotlin List type (and other types from the collections package) in dynamic libraries? the generated headers indicate that a <pkg>_kref_kotlin_collections_List type is being used, but I can’t find any docs on it

[Dico]

Create an API in your dynamic library that you can use to create and manipulate them.

[Michael Bryant]

sorry, i don’t understand. if i wanted to write C code to add an item to a kotlin List, what would that look like? do I have to add boilerplate to my kotlin code to do so?

[Dico]

yes, you have to create a function in Kotlin that will do it.

[Dico]

A top-level one

[Michael Bryant]

do you have any example code? i can’t find almost any examples of using dynamic libraries

[Dico]

I do not, and I'm not an expert here so please don't take my words for granted.

[r4zzz4k]

https://kotlinlang.org/docs/tutorials/native/dynamic-libraries.html
Here's general documentation on C API provided by K/N compiled into dynamic library. As you can see, all the methods should be available, namespaced by module name and package, taking object as the first argument.

[r4zzz4k]

Are stdlib classes covered in the same way in your generated headers?

[Michael Bryant]

is that a question? i have no idea. if i have a simple function that takes e.g. List<Int>, i don’t know how (in C) to instantiate the list to pass it in

[Michael Bryant]

the previous commenter suggested that i need to make top-level boilerplate functions to make a list, like

fun make_int_list(): MutableList<Int> {
    return mutableListOf<Int>();
}

[Michael Bryant]

well, that appears to work for list operations. i guess i can build on that

[Dico]

I'm not certain but you might have to work with StableRef as well.

[r4zzz4k]

I mean, you can check the header, right? You see your own make_int_list there. I'm curious, is mutableListOf represented somehow or not?

[Dico]

That's an inlined function I believe. I would be curious as well.

[Dico]

You would want to find the ArrayList constructor and invoke it.

[r4zzz4k]

Right. It's also a generic over boxed primitive, which I have no idea how to work with via C code, as boxing isn't covered by the doc :(

[Michael Bryant]

ah, i see what you were saying. no, nothing other than my custom classes/functions are represented in the header file

[Michael Bryant]

so no mutableListOf, etc

[Michael Bryant]

the stdlib classes that are represented in func signatures get their own struct definitions, so i can dispose of them using the normal pinned pointer ref

[olonho]

List is no different from any other type fo reverse C interop, library must expose all required operations. -Xexport-library may be helpful to add single helper .klib to multiple dynamic libs.