Hey there, can smbd please explain me, what’s the purpose of `state {…}`? Is it smth that’s used to ...

# compose

[Sheroz Nazhmudinov]

Hey there, can smbd please explain me, what’s the purpose of state {…}? Is it smth that’s used to control the state of the UI? If possible with an example, pls.
AFAIK, the source of truth for the UI should be a model class (Model annotated class). Correct me if I’m wrong here.

[Adam Powell]

It's an alias for

remember { mutableStateOf(...) }

[Adam Powell]

mutableStateOf<T>(initialValue) returns a MutableState<T>, which also implements the read-only interface State<T>. The returned implementation is backed by the same @Model infrastructure, so changing its .value property has the same effect as changing a property of a @Model class

[Adam Powell]

it also supports property delegation, so you can write

var myState by state { 0 }

and simply reference myState as an Int var that will be observed by the composition when it changes

[Adam Powell]

it's useful when you don't need a whole new class or type as a holder of mutable state

[Sheroz Nazhmudinov]

oh I see, that clears it out for me. I wasn’t sure if I have to create Model class for every state of my component. Thanks 👍

[Adam Powell]

nope! That would be kind of a pain, and MutableState<T> would be one of the first things you'd write to avoid having to do that all over, so it's built-in 🙂

[Sheroz Nazhmudinov]

exactly 😄 thanks for the clarification!

[Adam Powell]

Definitely check out state hoisting patterns though, a bunch of private state in your composables can start to get a bit difficult to work with as your app grows.