Is there a KEEP or youtrack issue for adding the c...

# language-proposals

[Saiedmomen]

Is there a KEEP or youtrack issue for adding the capturing subjects feature that when has, to more(or all) language control flows?

when (val response = executeRequest()) {
            ...
        }

https://kotlinlang.org/docs/control-flow.html#when-expression

[dmitriy.novozhilov]

Can you elaborate please?

[Saiedmomen]

Smart cast to non null wouldn't work in a situation like this

private val _stateFlow = MutableStateFlow<State?>(null)
    val state: StateFlow<State?> = _stateFlow
    if (state.value != null) {
       state.value.collection // open or custom getter
    }

Is there a proposal to support capturing the value in control flow statements itself?
something, very crudely like

if ((val sv = state.value) != null) {
       sv.collection
    }

[dmitriy.novozhilov]

You already can do it for `when`s
AFAIK there is no such request for `if`s, so you can report one

[hfhbd]

At least with state flows: the value could change in the time, so it would be better to use a custom variable, which works with smart casts.

[Youssef Shoaib [MOD]]

Or in this case you can use a simple state.value?.let {}. It even works if you need extra conditions state.value?.takeIf { it.followsACustomSetOfChecks() }?.let {} and you can have an else using the elvis operator ?: (keep in mind though that the elvis will trigger if let returns a null, so a better idea is to use also instead of let

[Saiedmomen]

Yes thanks. I usually prefer to just manually capture the value and write the logic with if-else's. I find it more readable