I have a question of understanding about re-composition. I have written the following simple code example:

@Composable

fun StateDemo() {

var counterOne by remember { mutableStateOf(0) }

var counterTwo by remember { mutableStateOf(0) }

var items = remember { mutableStateListOf<Int>() }

Column {

Button(onClick = { counterOne++ }) {

Text("One")

}

Button(onClick = { counterTwo++ }) {

Text("Two")

}

Button(onClick = { items.add(counterOne) }) {

Text("List")

}

MyText(counterOne)

MyText(counterTwo)

MyList(items)

}

}

@Composable

fun MyText(counter: Int) {

Text("counter: $counter (${System.currentTimeMillis()})")

}

@Composable

fun MyList(items: MutableList<Int>) {

Text("list: ${items.size} (${System.currentTimeMillis()})")

}

Unfortunately, the behavior in case of re-composition is not completely clear to me. If I click the button "One", the function "*MyText(counterOne)*" is re-drawn, the function "*MyText(counterTwo)*" remains completely unaffected. The behavior with the button "Two" is similar. Unfortunately in both cases the function "*MyList(items)*" is also redrawn. The behavior is not clear to me. What am I doing wrong! I want to prevent this function from being drawn, because in my opinion it is not involved in the re-composition. Many thanks in advance!

@jim How about using

mutableStateOf<List<Int>>()

?

@jim Thanks for the tip with the

SnapshotStateList

. I know that "Compose" can call the function at any time, I just wanted to keep the parts to be drawn as small as possible for performance reasons.

@Se7eN No, that would not do what you want, as

List<Int>

does not guarantee the list won't change, it only states avoids the reference holder from being able to call the mutation methods.

Thank you very much!

@Leland Richardson [G] Just started working on a feature to do what @jim describes above. He is streaming part of his work on YouTube and Twitch. A recording of the first "episode" can be found here () which also described much of the mechanism the compiler uses to decide if a function should skip or not as well as what changes we are making to make the above work the way you expected.