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Untitled.kt

Is this considered to be executed on the main thread?  How do you execute a coroutine on the background thread?  to be clear `exchangeRepository.getExchanges()` is the call to the `suspend` function.

I believe that `viewModelScope` runs by default on `Dispatchers.Main`, so it does run on the main thread. If you want to move the execution context to a background thread you could use `withContext()`

Yes, this will execute on the main thread as `viewModelScope` uses the `Dispatchers.Main.immediate` dispatcher by default, but this is actually how it should be set up, preferably. The “structured concurrency” expectation is that if any given `suspend` method needs to be executed on a different dispatcher, that it should move itself there, rather than requiring the callers to be on the proper dispatcher.

So make sure the API call is done on `<http://Dispatchers.IO|Dispatchers.IO>` internally by wrapping its implementation with `withContext(<http://Dispatchers.IO|Dispatchers.IO>)`, and you shouldn’t have to worry about changing dispatchers for it in the ViewModel

so in that case, then is this the correct way to set up the scheduler to be executed on a background thread?

Following Casey's recommendation, you could instead do:
```ExchangeRepository {
    suspend fun getExchange(...) = withContext(<http://Dispatchers.IO|Dispatchers.IO>) {
        ....
    }
}```


okay so set up the threading in the repository.

probably makes sense if you need to invoke that method in multiple places

Neither, ideally you’d have `withContext(<http://Dispatchers.IO|Dispatchers.IO>)` in your Repository, not the ViewModel.

```class ExchangeRepository {
    suspend fun getExchange() = withContext(<http://Dispatchers.IO|Dispatchers.IO>) {
        // ...
    }
}```

what about if you need to return a value from the repo function?

how do you return within the withContext block?

An additional recommendation: to make your repository more testable, you should pass the CoroutineDispatcher as a dependency:
```class ExchangeRepository(
    private val dispatcher: CoroutineDispatcher = <http://Dispatchers.IO|Dispatchers.IO>
) {
    suspend fun getExchange() = withContext(dispatcher) {
        ...
    }
}```

It’s a lambda, the last line of the block will be returned from it

nevermind … it looks like i just have to remove the `return` keyword

and then whatever is the last statement executed will be returned

or use `return@withContext` if you want to be explicit