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I agree with you in that using `MutableLiveData` for achieving this feels wrong. I think this is because:

- `LiveData` is meant for sending data *to* `LifecycleOwner`s such as `Activity` or `Fragment`, abstracting the lifecycle away, and your workaround sends data in the opposite direction.
- as a result, if your `View` happens to send data by through `MutableLiveData` while the lifecycle is stopped or paused, any callback you attach on the `MutableLiveData` on the `ViewModel` side simply will not run, which is probably not what you would expect.
- afaik `View`s are not `LifecycleOwner`s in the first place.

-----

What I've seen in most projects when they want to react to a Button click is that the Activity sets a View.OnClickListener as an anonymous class:

```
class MyActivity: Activity() {

    private lateinit var viewModel: MyViewModel

    override fun onCreate(...) {
        super.onCreate(...)
        
        viewModel = ....
    
        myButton.setOnClickListener {
             viewModel.myActionTriggered(...)
        }
    }
}
```


So to me, it makes sense to do something along those lines in your case too:

```
class MyActivity: Activity() {

    private lateinit var viewModel: MyViewModel

    override fun onCreate(...) {
        super.onCreate(...)
        
        viewModel = ....
    
        myCanvas.setListOfPointsListener { points ->
             viewModel.onListOfPointsChanged(points)
        }
    }
}

```

This way:
- neither the `Activity` nor the `ViewModel` need to implement the ad-hoc interface
- the `ViewModel` doesn't need to expose anything "mutable"
- the `LiveData` get data out of the `ViewModel` to the `Activity` as it should, not the other way around
- the `ViewModel` can still get the data from the `View` even when the lifecycle is "off", and it still can change its internal state in this case (other than posting to other `LiveData`, which would not work until the lifecycle is back "on")

----

A little off-topic comment: I think the name of `ListOfPoints` does not reflect what your interface does does. Your Activity doesn't become a "list of points", but rather a list of points *listener*. It doesn't contain the points itself, it just does something whenever that list changes.