Is it advisable to pass state objects as parameters to composable functions? If not what are the imp...

# compose

[Rafs]

Is it advisable to pass state objects as parameters to composable functions? If not what are the implications. I'm referring to something like this.

@Composable
fun StyledText(
    text: State<String>,
) {
    Text(text = text.value)
}

[Colton Idle]

I don't know the implications... BUT I do remember seeing something in the docs a while back where they tell you that you shouldn't be passing in snapshot state Types like this

[Rafs]

I remember seeing something similar a long time ago but I don't remember what was said about it, other than not using it. I'm trying to discourage my team from using it but I don't have any strong points to say about that, other than losing the delegate property

[Stylianos Gakis]

Pass () -> T instead.

The reason is simple, you still get the benefit of deferred reads when you need that.
But () -> T also allows you to pass a normal non-state object.
If you use State<String> instead as you show above, and you don’t have a state at some call-site, you’d need to turn your normal parameter into a state just to pass into this clunky API. Don’t do it.

[jefbit]

https://developer.android.com/jetpack/compose/state-hoisting

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

lowercase-s “state” objects, i.e. state holder classes that have snapshot-backed state internally, yes, if there are other reasons to factor out a state holder. Uppercase-s State types, no, for the reasons above.

[vide]

Just to clarify, you still do get the benefit of deferred reads when passing State<T> as a parameter. It's just that passing () -> T is better for the benefits mentioned by Stylianos & Zach.

[MR3Y]

I want a small confirmation here to see if I understand this correctly. As per my understanding this is not defering reads:

@Composable
fun StyledText(text: String) {
 ....
}

But these 2 are deferring reads:

@Composable
fun StyledText(text: State<String>) {
 ....
}

@Composable
fun StyledText(text: () -> String) {
 ....
}

Right?

[vide]

Yes, exactly