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kotlinlang

Is there any rule as to when I should use `.not()` and when I should use good old `!` <https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-boolean/not.html>

Someone on my team is using it. A lot. What should I tell him to discourage him?

`!condition` is used in most programming languages (or at least in most of those I know). Because it is more familiar to non-Kotlin developers, I think i'ts more readable than `condition.not()`, especially in long conditions.
AFAIK the Kotlin compiler may not fully optimize the `.not()` function call in some cases, compared to when using `!`

I'd expect `!` and `.not()` to be bytecode-equivalent since `.not()` is just an operator function, btw.

having a postfix negation method just seems unnatural to me. it's more obvious to say "not some condition" instead of "some condition, not"

I wonder if they were influenced by Borat english in this case :thinking_face:  This is great... NOT!

I don't know for sure that you can "convince" someone of this based on merit alone...I'd say have a team style guide and enforce it.

OK, but if its not  a good idea, then what sort of cases was the operator designed for?

Out of curiosity:
```fun test(): Boolean = true
fun main () { test().not() }

// decompiled
public static final boolean test() { return true;}
public static final void main() { if (!test()) {} }```


I guess Kotlin doesn’t optimize that out

@Jacob maybe for Unit testing during expects. I come from Jasmine/Mocha world and I see that a lot

I think it's just how the `!` operator is implemented

just because you can call `plus` doesn't mean you're supposed to call it by that name

that's the kind of operation the JVM would optimize out I think

<@U01D1MKSGAG> it'll optimize it with a `const val`, otherwise it's not constant and can't be inlined at compile time.

<@U011VAU1NS3>
&gt; Someone on my team is using it. A lot. What should I tell him to discourage him?
"You must unlearn what you have learned." (c) Yoda