```@Composable private fun ZoomControls( zoom: Float, onZoomChanged: (Float) -> Unit ) { ...

# compose

[carbaj0]

@Composable
private fun ZoomControls(
    zoom: Float,
    onZoomChanged: (Float) -> Unit
) {
    Row(Modifier.fillMaxWidth(), horizontalArrangement = Arrangement.Center) {
        ZoomButton("-", onClick = { onZoomChanged(zoom * 0.8f) })
        ZoomButton("+", onClick = { onZoomChanged(zoom * 1.2f) })
    }
}

ZoomControls(zoom) {
        zoom = it.coerceIn(MinZoom, MaxZoom)
    }

This is a bit confusing since being a Composable, I expect the lambda to be a content: @Composable () -> Unit instead of a callback.

[Zach Klippenstein (he/him) [MOD]]

Lots of composables take callback functions that aren't composables. remember, Button, TextField, etc. It doesn't make sense for callbacks to be composable, since they represent events, not descriptions of UI.

[carbaj0]

in the case of remember it´s fine, because I don´t expect it to return a representation in the ui.
when I see an Composable in Uppercase, I expect that if the last param is a trailing lambda is for taking other Composables

[carbaj0]

but it's only my interpretation jeje

[Zach Klippenstein (he/him) [MOD]]

Not sure what’s confusing about this – the parameter is named following the “on*” pattern, implying that it’s a callback, and it’s not marked @Composable, so it’s clear it’s not a composable.

If it’s seeing code using the trailing lambda syntax, like ZoomControls(zoom) { … }, that’s confusing, there I’d agree and would probably rather write the lambda inside the parenthesis with an explicit parameter name (I’d do this for all callbacks). It would be nice to have a lint check warning against using trailing lambda syntax for callbacks.

[Adam Powell]

Fwiw you're in good company in thinking about this, we've had a decent amount of internal debate on whether the API guidelines should take a strong opinion here or not

[Adam Powell]

For the same reasons

[Adam Powell]

So far I'm in camp, "no restriction" but I could be swayed

[Adam Powell]

For example, onCommit is due for a rename and a rework as it's a Unit-returning composable function where its presence or absence in the composition is significant. Same as a button or dialog. Its body lambda is not @Composable nor should it be. Nor would I want to add trailing fingernail clippings and avoid the trailing lambda syntax for it

[Adam Powell]

Same for launchInComposition

[Adam Powell]

Consider also things like an OnBackPressedHandler