Hello how one can define a multiple derivedStatedOf I have a

Question

Hello how one can define a multiple derivedStatedOf I have a code like below but they are called constantly when I log and recomposition happening As far as I understand correctly recomposition should only happen when `isPageTitleReached` and `isContentScrolled` changed right ```val isPageTitleReached by derivedStateOf remember lazyListState firstVisibleItemScrollOffset gt 500 val isContentScrolled by derivedStateOf remember lazyListState firstVisibleItemScrollOffset gt 600 ```

myanmarking · Answer

you inverted the function calls It should be remember derivedStateOf

myanmarking · Answer

remembers like that are useless The block inside will only run once

nuhkoca · Answer

ohh really fixing this right away thanks for the heads up Will update you

nuhkoca · Answer

btw why it is like I did in the official doc ```val highPriorityTasks by remember highPriorityKeywords derivedStateOf todoTasks filter it containsWord highPriorityKeywords ```

myanmarking · Answer

the reason they are called constantly is because derivedState that in not remembered will create a new instance every recomposition

myanmarking · Answer

remember derivedState you have derivedState remember

nuhkoca · Answer

ahh my bad sorry you are right

nuhkoca · Answer

Hey < myanmarking> can I have something like this or is it a good way on Compose Basically I d like to hold all variables inside a data class but wondering if `remember` and `derivedStateOf` would work as expected in my example ``` Composable private fun rememberScrollState lazyListState LazyListState firstCondition Int secondCondition Int = remember firstCondition secondCondition ScrollState lazyListState firstCondition secondCondition ``` ``` Immutable private data class ScrollState val lazyListState LazyListState val firstCondition Int val secondCondition Int val isPageTitleReached by derivedStateOf if lazyListState firstVisibleItemIndex == 0 lazyListState firstVisibleItemScrollOffset gt firstCondition else true val isHeroScrolled by derivedStateOf if lazyListState firstVisibleItemIndex == 0 lazyListState firstVisibleItemScrollOffset gt secondCondition else true ```

myanmarking · Answer

Ya it should work You should probably add the lazyliststate to remeber param as well

myanmarking · Answer

And probably change immutable to stable

nuhkoca · Answer

Awesome applying right now Thanks for the quick turnaround appreciate it pray

Michael Paus · Answer

Which leads me to the question whether a data class with only val parameters needs any of these qualifiers Immutable Stable at all I thought such a data class is considered stable by default

myanmarking · Answer

Well you can have a val that is unstable It is not the only requirement Im not sure about this case would have to check but it doesnt hurt adding it

Tash · Answer

IIRC the Compose compiler can infer immutability and stability only on classes which are compiled in modules where the Compose compiler enabled So even if your `data class` has `val`s where nothing is backed by mutable data it won t be inferred as immutable unless it is in a module w the Compose compiler Also if your `data class` contains a `val list List lt Foo gt ` the compiler can t infer stability even if `Foo` is stable there s an open For that you d have to explicitly annotate that class with ` Immutable` ` Stable` Recently read about this here

Michael Paus · Answer

< Tash> Very interesting reading especially the link to I proposed exactly that here some months ago but the idea was bluntly rejected