Hi, I am trying to migrate my app architecture (wh...

# android-architecture

[amatkivskiy]

Hi, I am trying to migrate my app architecture (which is basically Clean Architecture based on RxJava) to Clean Architecture based on kotlin coroutines. There is one thing that I am still struggling is coroutines dispatchers. Previously with RxJava it was common to place main thread and background Schedulers in UseCase and then use them when creating Observable.
Right now I see that in some cases developers put coroutine dispatchers in UseCase and then triggering coroutine with specific dispatchers. In other cases I saw that UseCase was made basically just a suspend function and all work related to dispatching was moved to the caller of the UseCase. Any ideas what is more correct way to do this?

[sergio250]

I’d say letting the caller decide the execution context is often a better solution for two reasons, this way you don’t have to differentiate between sync/async UseCases, and you can run some potentially expensive computations (like mapping domain to UI models) in a background thread from the caller

[amatkivskiy]

@sergio250 thanks, I was also more to this approach

[sergio250]

I think I have some (very basic) example of this approach in a Kata we use for UI testing in my company

[sergio250]

https://github.com/Karumi/KataSuperHeroesKotlin/blob/master/app/src/main/kotlin/com/karumi/ui/presenter/SuperHeroDetailPresenter.kt

[sergio250]

Found it, UseCases are not suspended though 🤔

[amatkivskiy]

let me have a look

[oday]

why don’t you join #coroutines

[amatkivskiy]

@oday because this topic relates more to general architecture rather than coroutines

[amatkivskiy]

@sergio250 I found one possible cause that may require dispatchers : when parallel work is required (like making multiple network simultaneously ) then you will need context to properly use async await stuff

[sergio250]

You are right 🤔

[amatkivskiy]

On the other hand there is coroutineScope {} which as far as I understood creates a child scope based on the parent and allows to call async await coroutines

[Sam]

Yes, you can have an extension on CoroutineScope when launching coroutines

[Sam]

https://medium.com/@elizarov/explicit-concurrency-67a8e8fd9b25