I was trying to write an extension in Swift on a g...

# kotlin-native

[hannesstruss]

I was trying to write an extension in Swift on a generic Kotlin type (to add Swift Combine support to SqlDelight's Query<RowType>). @russhwolf suggested using a top level func like func createPublisher<T>(query: RuntimeQuery<T>) -> AnyPublisher<RuntimeQuery<T>, Never> . That works! Are there maybe any other solutions?

[hannesstruss]

My code that doesn't compile:

extension RuntimeQuery {
  func asPublisher() -> AnyPublisher<RuntimeQuery<RowType>, Never> {
    // ...
  }
}
// Fails with: 'Extension of a generic Objective-C class cannot access the class's generic parameters at runtime.'

[hannesstruss]

@saket pointed me to this from Badoo's Reaktive: https://github.com/badoo/Reaktive/pull/393

[russhwolf]

Yeah I originally dug into this in the context of converting between coroutines/flow and RxSwift. The solution there required wrappers similar to what Reaktive uses to get the generic exposed to Swift, and then top-level functions in Swift to have generic transformers to RxSwift types.

[hannesstruss]

That probably entails one wrapper per concrete type, right? Was hoping to avoid that, but for my tiny side project it should be okay.