Whether null counts as true or false depends on th...

# language-proposals

[natpryce]

Whether null counts as true or false depends on the context. If I have a nullable bool, I use the Elvis operator:`if (state?.isValid ?: false) ...` or if (state?.isValid ?: true) ...

[gildor]

Style guides from JB recommends to use nullableBool == true and nullabelBool == false instead

[gildor]

But I like to use elvis operator for local variables to make them non-nullable.
It’s easier to understand what’s going:

val isValid = state?.isValid ?: false
if (isValid) …

[natpryce]

Do you have a link to that styleguide?

[gildor]

Not published to kotlinlang.org yet, but I suppose will be there soon
https://github.com/JetBrains/kotlin-web-site/blob/yole/styleguide/pages/docs/reference/coding-conventions.md#using-nullable-boolean-values-in-conditions

[natpryce]

I think that gets confusing when you deal with negated conditions.

[natpryce]

E.g. if (maybeState != false)

[natpryce]

because the null case is obscured

[natpryce]

While using an elvis operator makes that clear

[natpryce]

Oh well… they’re only guidelines and IntelliJ can automatically switch code between different styles with the same meaning

[gildor]

Yes, I agree that maybeState != false can be confusing, so just declare non-nullable local variable with elvis operation is reasonable alternative in this situation

[gildor]

but for simplest: maybeState == true is clear enough for me