This is my variation of hadliq/LiveEvent described here https://proandroiddev.com/livedata-with-single-events-2395dea972a8

The only difference is that my version has a pending flag such that if no observers have ever observed a value the LiveEvent will hold it and emit it to the first observer. Once observers start observing values then it emits a value. New observers have to wait for the next value to be set.

The reason I did this was to work-around a race condition where it's possible to set an initial value in a LiveEvent before any observers have started observing. If that happened then in hadliq's original implementation the event would be lost. This introduced a lifecycle dependency to the LiveEvent I didn't like.

For example, if for whatever reason an event was emitting in an init block of a ViewModel.

class MyViewModel: ViewModel() {
  val liveEvent = LiveEvent<String>()

  init {
      liveEvent.value = "I might get missed"
  }
}

The first observer will seee the pending value. It should still emit a value just once. All new observers will have to wait for new events to be set.

I tried to PR it back to the original author but he didn't like my reasoning so I'm forking it.