why doesn t this compile ```val countries by remember listOf kotlinlang #compose

11/12/2020, 11:01 PM

why doesn't this compile:

val countries by remember { listOf(Locale.getISOCountries().map { Locale("", it) }) }

with exception:

Type 'TypeVariable(T)' has no method 'getValue(Nothing?, KProperty<*>)' and thus it cannot serve as a delegate

11/12/2020, 11:02 PM

mutableListOf

11/12/2020, 11:03 PM

does not work either @Ian Sikes

i suspect i have a misunderstanding with how to store lists in state with

remember

but i can't find any examples

11/12/2020, 11:07 PM

mutableStateListOf

? haha I haven't quite got it either. The codelabs seem to cover

mutableStateOf

but not these other uses

Zach Klippenstein (he/him) [MOD]

11/13/2020, 12:28 AM

mutableStateOf

MutableState

getValue

setValue

) defined as extension functions, which is why that works.

remember

just returns whatever you return from the lambda – it doesn’t change the type. So if what you’re returning can’t act as a delegate, this won’t work.

11/13/2020, 12:29 AM

so is the solution to use

mutableStateOf

even for lists?

Zach Klippenstein (he/him) [MOD]

11/13/2020, 12:29 AM

List

SnapshotStateList

can be delegates

so is the solution to use mutableStateOf even for lists?

Yes, the list is your state here.

Although you only need to do that if you actually need to change it. If you don’t, just remembering the list directly is fine, but then use

by

11/13/2020, 12:31 AM

that's what i was about to ask, since the list here is immutable.. just want to make sure it doesn't recalculate the map transform on every render

Zach Klippenstein (he/him) [MOD]

11/13/2020, 12:32 AM

It won’t, anything in the

remember

lambda will only be executed once