Is there a better way to do this? The goal is for ...

# coroutines

[alexhelder]

Is there a better way to do this? The goal is for the assignment to items to not block the thread:
• daggerLazyPagerFactory is dagger.Lazy, get() bocks the thread in my case
• i have the flow { } builder just with a single emitAll, which seems wrong, but moves the blocking get() to Dispatcher.Default

val items: Flow<PagingData<Item>> = flow {
        emitAll(daggerLazyPagerFactory.get().flow())
    }.flowOn(Dispatchers.Default)
        .cachedIn(viewModelScope)

If I try this, get() blocks the thread, as flowOn{} does not impact that:

val items = daggerLayPagerFactory.get()
   .flow()
   .flowOn(Dispatchers.Default)
   .cacheIn(...)

[Robert Williams]

Don't see anything wrong with this, it's kind of a common pattern when you need to do async init for the flow (definitely much better than the dreaded suspend funs which return flow)

[Robert Williams]

See for example https://slack-chats.kotlinlang.org/t/488968/i-have-a-suspending-function-that-returns-a-flow-it-seems-li

[Robert Williams]

You may prefer to rearrange things to make it clearer you're doing async init:

flow {
     val pager = withContext(Dispatchers.Default) {
       daggerLazyPagerFactory.get()
     }
     emitAll(pager.flow())
    }

And then you won't need flowOn

[alexhelder]

Thanks! TIL you can do withContext in flow{ } builder as long as you don’t emit anything in its block, I though this violated the context preservation policy. Also thanks for the heads up about dreaded suspend funs returning flows, if its a bad I idea I will come up with it eventually 😆