I have a question, What's the difference between ...

# compose

[chanjungskim]

I have a question,

What's the difference between

val interactionSource = remember { MutableInteractionSource() }

and

val interactionSource by remember { MutableInteractionSource() }

and

val interactionSource by rememberSavable { MutableInteractionSource() }

???

[Jakub Syty]

First one returns State<MutableInteractionSource> which, if you want to read/save you have to use like interactionSource.value = <something>

[Jakub Syty]

Second one is just a simple delegate that makes working with that easier, like interactionSource = <something>

[Jakub Syty]

The last one is exactly the same as second, but it stores the state across android lifecycle, so it will be save when used rotates the screen or something else that will trigger configuration change

[chanjungskim]

As I remember, In the codelab = remember { } is not recommended. But is this still useful?

[chanjungskim]

Maybe for flow?

[Jakub Syty]

Why not recommended? This is a valid usage for many usecases

[Jakub Syty]

if you don't care about saving that particular state simple remember will be faster

[chanjungskim]

Aha, I see! thank you 🙂

[Loney Chou]

MutableInteractionSource is not a State

[Colton Idle]

https://dev.to/zachklipp/remember-mutablestateof-a-cheat-sheet-10ma

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

Yea the second 2 won’t compile because MutableInteractionSource doesn’t define a getValue method.

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

Only State does that (and MutableState additionally defines setValue)
Sonly

[mattinger]

Also, i'm not convinced that an InteractionSource would be saveable anyway. Things give to a rememberSaveable need to generally be serializable in some form, or you need to pass a Saver to it to tell it what to do. I'm not convinced MutableSharedFlow meets this requirements. It's basically a wrapper for a MutableSharedFlow.

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

Yea it doesn’t make sense to save an MIS, and i don’t think it supports it.

[Bobby Hargett]

I am probably doing something wrong, but I have a
val x = remember {...)
SomeComposeThatChangesX(x)
SomeComposeThatShowsADifferentViewOnX(x)

I know this could probably be done via a viewModel with 2 and 3, but I think 1 is easier

[Bobby Hargett]

So x.value can be used in SomeComposeThatChangesX