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kotlinlang

Can anyone explain to me the benefit of a `CoroutineScope` being provided in AndroidX LifeCycle as an extension `viewModelScope` versus just having viewmodel implement `CorutineScope`?

Nevermind, just found out that `viewModelScope` doesn't use a `SupervisorJob` under the hood. That's a non starter for me

<@U5D6V79TL> Latest versions of it should use `SupervisorJob` under the hood. You can see all the latest versions on <http://maven.google.com|maven.google.com>

I've actually stumbled upon a good way to do it which is to take as a param a CoroutineScope and implement that interface by delegatation. Should help with testing too

which seems very convenient for my use case

Don't forget to call `cancel()` from `onCleared()`

```abstract class CoroutineViewModel(private val scope: CoroutineScope) : ViewModel(), CoroutineScope by scope {

    override fun onCleared() {
        super.onCleared()
        this.cancel(CancellationException("ViewModel called onCleared"))
    }
}``` :slightly_smiling_face:

The benefit is composition over inheritance. If they change their mind about coroutines, the ViewModel will remain untouched. Also, coroutines is just another external library and it's a tall ask to depend on it.

Also, you can make your `onCleared()` override final, or annotate it with `@CallSuper` if you still need to override it in subclasses.