Can I pass down a `MutableState` into a `@Composab...

# compose

[reactormonk]

Can I pass down a MutableState into a @Composable function, and use var value by mutableState at the outer function and expect a recomposition once the inner function changes MutableState?

[Hrodrick]

If I understand correctly what you want to achieve, yes you can. In fact some use cases may only be achieved using that approach

[vide]

don't forget to remember

[Stylianos Gakis]

Do not pass down MutableState down to your composables.
https://kotlinlang.slack.com/archives/CJLTWPH7S/p1644852692627449?thread_ts=1644783454.508379&cid=CJLTWPH7S

[Hrodrick]

I don’t get why you should pass the lambda, why not just receive the SomeData object directly?

[Stylianos Gakis]

Only if you need to defer the state read to a scope further down in your composable tree. It’s an optimization to reduce recompositions. 99% of the time you don’t need it. Sometimes however it is a good idea.

[Stylianos Gakis]

some use cases may only be achieved using that approach

No that isn’t true, you can always pass down the state read lamba + a lambda to change the state too. Which is always a better idea than passing MutableState at least.

[reactormonk]

Didn't need it after all, but thanks for the info, will keep in mind.

[Hrodrick]

yeah I think I get it now, as long as the function is not re-created when whatever it is used inside to give the state changes, you will need to be careful with that, is not just “replacing X with Y” 🤔. Otherwise it will be the same as sending the State directly