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#getting-started
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# getting-started
l

Lukasz Kalnik

07/15/2022, 8:42 AM
Is there no smart cast in case of `OR`ed null checks inside of 
if
?
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val selectedScene1: String? = // ...
val selectedScene2: String? = // ...
if (selectedScene1 != null || selectedScene2 != null) {
    val sceneToFind: String = selectedScene1 ?: selectedScene2!! // The !! are necessary to make this work
}
m

Michael de Kaste

07/15/2022, 8:47 AM
a combination based smartcast isn't really possible since the nullability of one now relies on the nullability of the other. What you however can do is something like
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listOfNotNull(selectedScene1, selectedScene2).firstOrNull() //on null, you're not in your 'if'. On value, you are.
l

Lukasz Kalnik

07/15/2022, 8:49 AM
Smart solution, thank you!
So the non-nullability in the line with 
?:
cannot be resolved at compile time if I understand this correctly.
Although logically 
sceneToFind
should always be non-nullable inside the 
if
(even without the 
!!
). But I suppose the nullability is resolved by type checker which doesn't follow the logic of the program but just statically compares resolved types.
e

ephemient

07/15/2022, 9:53 AM
if you remove
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if (selectedScene1 != null || selectedScene2 != null)
and replace it with
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val sceneToFind: String? = selectedScene1 ?: selectedScene2
if (sceneToFind != null) {
then you will get effectively the same result, but safely
l

Lukasz Kalnik

07/15/2022, 9:59 AM
True, that's also a good solution. 🙏
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