What is the difference between these two? ```var a: Boolean by remember { mutableStateOf(false) } va...

# compose

[Paul Woitaschek]

What is the difference between these two?

var a: Boolean by remember { mutableStateOf(false) }
var b: Boolean = remember { false }

[myanmarking]

first one is MutableState<Boolean>, second is just Boolean

[myanmarking]

remember { false } is kinda pointless i think. If the value is ‘constant’, no point in remembering it i think

[myanmarking]

also, i think there is no point in mutableState with val also. If you cannot mutate it

[myanmarking]

to answer the question directly, in terms of behavior as they are defined, i would say they are the same. But i am no expert in compose

[Paul Woitaschek]

They are meant to be mutable ofc

[Tgo1014]

I guess the second one doesn’t trigger a recomposition 🤔

[myanmarking]

ok. then, once the first one value changes, it will recompose (false -> true) and (true - false).

[Filip Wiesner]

Oh, now that you've changed them to var it is different. First will recompose on change and second does nothing. And by nothing I mean it's pointless. You could just write var b = false

[hfhbd]

Compose only updates (recompose) its content, when a State changes. remember keeps the changed states between recomposing, otherwise the State would be the init state after recomposing.

[Paul Woitaschek]

Great answers, thanks! 🙏

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

The second one won't just not cause recomposition, every time it recomposes it will be set to false again if even you changes some previous composition’s “version” of the var. There's nothing special about vars in compose. remember is just asking the composition what value its lambda returned the first time it was composed.

[Paul Woitaschek]

Why isn't the remember lambda constrained to State?

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

Because there are lots of times when you want to remember something else, eg a mutable state holder that has `MutableState`s inside.

[Adam Powell]

remember provides persistence, snapshot state provides transactionality and observability. They're orthogonal.