Correct me if I'm wrong, but there doesn't seem to...

# kotlin-native

[serebit]

Correct me if I'm wrong, but there doesn't seem to be a way to call a non-static and capturing function on program exit in kotlin/native.

[olonho]

You can read such lambda from the global, although

[serebit]

I have a class that needs to send a close notice to its websocket connection before the program exits. This is doable on JVM, as I can add a hook to the program exit and run that operation, but I can't perform the same on kotlin/native due to its non-static and capturing nature.

[serebit]

I can't store a collection of websocket sessions in the class's companion object due to objects being frozen by default, either. It seems like there's genuinely no way to accomplish this.

[olonho]

Is it UI program?

[serebit]

It’s a library that’s intended to be used from the command line, but a frontend for it could in theory have a UI. The entire system is non-blocking and relies heavily on structured concurrency.

[olonho]

The its likely not how it shall be done in general. If you have structural concurrency, then resource mgmt shall be structural too.

[olonho]

Adding state to global list (on exit handlers) is not the best idea. Why not implement smth like https://kotlinlang.org/api/latest/jvm/stdlib/kotlinx.cinterop/mem-scoped.html but for websockets

[serebit]

You’ve got a point. The main issue I see is that I don’t know where I’d even begin if I wanted to implement something like that, especially in the context of multiplatform.

[serebit]

If you have any suggestions, I’d be happy to hear them. I’m very interested in the idea of scoping websockets in such a way.

[olonho]

It’s rather simple and generic - create resource manager class (like MemScope in above example) which returns a resource and write function taking extension lambda on that class, and freeing resource after executing it. Understand how memScoped works, then things will be pretty clear.

[serebit]

I'll see what I can do. Thank you for the suggestion, I really appreciate it!

[serebit]

So it looks like the resources are released in that finally block within the function. On JVM, the finally block doesn’t execute on process exit if it’s within a coroutine. Is this behavior different in kotlin/native?