I think I must not be getting a piece of the state hoisting

Question

I think I must not be getting a piece of the state hoisting puzzle I have a UI which is a list lazy of cards or status accompanied by a header with buttons at the top that can tune visibility options for things that show up in the cards To wit my basic structure looks something like ```Column var visibilityOptions by remember mutableStateOf VisibilityOptions Header options = visibilityOptions LazyColumn items things each gt ItemCard each options = visibilityOptions ``` Half of this works The header which opens a dialog to tune the flags in visibility options seems to stay up to date with changes made But the ItemCards don t recompose I wondered if this was a case where I needed to pass the actual observable instead of its value the whole mechanism that compose compiler uses to figure out how variables retrigger compositions is sort of black magic to me at the moment so I tried changing that to ```var visibilityOptionsState = remember mutableStateOf VisibilityOptions ``` and then adding all of the various ` value` accesses But i get the same result No recomposition of the ItemCards What am I missing

Kirill Grouchnikov · Answer

What is visibility options Does it have a map or a list inside Those might need to be tracked differently

Travis Griggs · Answer

```data class VisibilityOptions var showID Boolean = false var showPower Boolean = false var showSignal Boolean = false ```

Travis Griggs · Answer

When I scroll the list the newly created rows pick up the changes

Kirill Grouchnikov · Answer

Probably needs val and usage of copy when fields need to change

Travis Griggs · Answer

``` Composable fun ValveRemotePrimaryRow valve ValveRemote optionsState MutableState lt VisibilityOptions gt = mutableStateOf VisibilityOptions Row SolenoidPositionBox valve = valve TitleBox namely = valve modifier = Modifier weight 1f showID = optionsState value showID AnimatedVisibility visible = optionsState value showSignal SignalBox AnimatedVisibility visible = optionsState value showPower BatteryBox ``` That s an abbreviated version of my cards

Pablichjenkov · Answer

Same if you try with key items key

orangy · Answer

If you change vars inside `VisibilityOptions` Compose has no means to track these changes You can either use immutable data class as Kirill said and change the `value` in the `visibilityOptions` state or you can replace simple vars with mutable state inside options like `var showPower Boolean by mutableStateOf false `

Travis Griggs · Answer

Thanks for the hints and pokes guys Subtle misuse of the `apply` function I did indeed have the vars and was doing the following when updating in my header ```optionsState value = options apply showPower = showPower not ``` which updated the options struct dataclass But since `apply` returns context object no change was triggered in the state container I ve switched to using the implicit copy when updating my options thing now and now everything works So in the end I understood the pattern better than I thought I did but just didn t drive Kotlin correctly confused