Hello, I have a global `Coroutines` (img1)to read something(?), when it's not null ,I want send this...

# compose-desktop

[毛小川]

Hello, I have a global Coroutines (img1)to read something(?), when it's not null ,I want send this to a function`@Composable` for update variables(mutableStateOf) ,How can I achieve? thanks!

[gildor]

You cannot send anything to a composable function, but you can update some state which is used by this composable function, using mutableStateOf or Compose

[gildor]

but it really depends how this receive() function is used, if it called from Composable function, it would be better to have some kind ViewModel/Repository for it and use it from you composable code

[毛小川]

Thanks! I was thinking of something like broadcasting

[gildor]

Yes, usage of StateFlow or mutableStateOf would allow to recompose your UI with new data

[毛小川]

Yes,I understand your suggestion,
before: I think about move mutableStateOf var from fun scope to class scope(img1) , crash!;
Now : I tried let the mutableStateOf var pointing a other var which in common scope(img2), brilliant!

[毛小川]

Thanks a lot!❤️

[gildor]

You shouldn’t wrap it to remember, you can just use state directly if it some shared state

[gildor]

remember is used to remember some object to keep it between compose recompositions

[gildor]

but if you declare mutableStateOf somewhere outside of composable function, no need to worry about missing it, it will just have the same lifecycle as class where it declared (or global if it top-level function)

[毛小川]

Could you give a good example?Thanks!
when I remove remember ,it's crash:

[gildor]

Crashes or not compiling?

[毛小川]

not compiling😭

[gildor]

No, you should always use remember inside of composable

[gildor]

but in this case you will not be able to update it from outside

[gildor]

what I mean is:

val hardVersion = mutableStateOf("test")

@Composable
fun fragmentBox1() {
    TextField(value  = hardVersion.value)
}

fun receive() {
   GlobalScope.launch {
     hardVersion.value = "something"
   }
}

[gildor]

https://kotlinlang.slack.com/archives/C01D6HTPATV/p1645761035089459?thread_ts=1645754743.153129&cid=C01D6HTPATV

It’s not compiling because you use hardVersion without get()

[毛小川]

Sorry,I can't find get() from MutableState

[毛小川]

oh! value?

[gildor]

yep, sorry, value

[gildor]

.get() is not from Compose %)

[gildor]

Updated example with value

[毛小川]

Thank you very much, you are very patient!❤️

[gildor]

Haha, no problem, hope it helpful
Just remember it’s more an example, and for real code I would rather abstract all those state loading and updating to repository/view model

[毛小川]

Mean this? Move any var to RuntimeContent such as hardVersion?

[gildor]

If they updated from outside of composable functions, yes, otherwise it's better to keep them internal

[毛小川]

Yes it is！I understand.Thanks a lot！

[Tobias Suchalla]

FYI, you need .value because you use mutableStateOf directly instead of as a delegate:

var x = mutableStateOf("hello")
Text(text = x.value)
x.value = "world"

vs.

var x by mutableStateOf("hello")
Text(text = x)
x = "world"