Which approach is more idiomatic in Compose? 1 or ...

# compose

[Arkadii Ivanov]

Which approach is more idiomatic in Compose? 1 or 2?

@Composable
fun foo1(dependency: () -> Dependency) {
    val x = remember { Bar(dependency()) }
}

@Composable
fun foo2(dependency: Dependency) {
    val x = remember { Bar(dependency) }
}

[Adam Powell]

I think you may be looking for:

@Composable
fun foo2(dependency: Dependency) {
    val x = remember(dependency) { Bar(dependency) }
}

where x will be the same instance so long as dependency doesn't change

[jim]

That assumes dependency is provably immutable, so you'd almost certainly want to go with the non-lambda variant to avoid accidental captures.

[Arkadii Ivanov]

Looks like same approach is used for Image, ImageAsset interface does not look like immutable

[Arkadii Ivanov]

Also found this code in Compose sources. InteractionState is clearly mutable.

[jim]

Image and ImageAsset had better be effectively immutable or that code is going to have the wrong behavior.

[jim]

The second example with remember in the default value of an optional parameter - that is very much idiomatic Compose, that is the best style of all of them, but it has different behavior from the code you mentioned originally.

[jim]

The second example (good, high quality, idiomatic code) only performs the remember if a value was not provided. The second example does NOT need to be immutable.

[jim]

in fact, for the second (good) example, doing the remember would be almost pointless if the remembered value were immutable.

[Arkadii Ivanov]

Agree about the second case, thanks!