How to limit producers from emitting events with property's existing value?

Question

Does setting the value of a MutableProperty result in the producer emitting a new event with the same value?

In other words, if I don't want new events with the same value, do I need to do this != check?

let really = MutableProperty<Bool>(false)

func updateReality(newReality: Bool) {
    if really.value != newReality {
        really.value = newReality
    }
}

score 0 · Accepted Answer · answered Oct 19 '17 at 12:23

Properties always send the new value, even if it's the same as the old value. It has to be this way or else you couldn't use it with non-Equatable types. But if you are dealing with an Equatable type, like Bool, then you can use the skipRepeats operator on your property to create a new property that only receives new values, and then expose that property to consumers:

let really = MutableProperty<Bool>(false)
let reallyWithNoRepeats = really.skipRepeats()

So you would update the value via really.value, but consumers subscribe to reallyWithNoRepeats to get new values only.

How to limit producers from emitting events with property's existing value?

1 Answers1