```fun <T : Any> Flow<T?>.validate( validator: (T) -> Status): Flow<Status> = distinctUntilChang...

# coroutines

[ursus]

fun <T : Any> Flow<T?>.validate( validator: (T) -> Status): Flow<Status> =
    distinctUntilChanged()
        .transformLatest {
            val valueAndMetadata = it ?: return@transformLatest <--------------
            emit(Pending)
            delay(500)
            val status = withContext(Dispatchers.Default) { <------------
                validator(valueAndMetadata)
            }
            emit(status)
        }

can anyone double check this?

is the usage of withContext in a transformLatest operator to offload a synchronous calculation correct?

I faintly remember someone complaining about switching dispatchers manually in flow operators

[CLOVIS]

What are you trying to do?

Switching dispatchers is risky because you can't emit from other dispatchers. In this case, you switch temporarily but go back to the original dispatcher before emitting, so I believe it's fine (but I'm no expert)

[CLOVIS]

Instead of val valueAndMetadata = it ?: return@transformLatest I would just use .filterNotNull() before the transformLatest

[ursus]

that would not unsubscribe the previous transformLatest

[ursus]

i have there heavy regexes which take a few ms, so nkt suitable for main thread