what's an idiomatic way of saying "if null, run th...

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[myaa]

what's an idiomatic way of saying "if null, run this and return null"? kind of like how also runs a function and then returns the original value, except that i only want to run the function if the original value is null
i've got something like

value.takeIf { it >= 0 } ?: run { println("Warning: negative value"); null }

except i'd like to avoid manually having to return null at the end of the run

[Derek Peirce]

If you need this pattern frequently, you can add your own doIfNull { ... } method, I doubt it's a common enough case to warrant anything in stdlib.

[Bornyls Deen]

I suppose you could use also for this but it doesn't look very nice to me.

val result = value.takeIf { it >= 0 } ?: null.also { println("Warning: negative value") }

If chaining the statements together isn't required I'd probably just use a more traditional approach

val result = value.takeIf { it >= 0 }
if (result == null) {
    println("Warning: negative value")
}

[myaa]

the thing is that this is for use as the return value of a short function, and defining a variable like that means having to add a bunch of other boilerplate (explicit return, explicit return type, braces)

another idea i had was to use an if/else expression, but it's not really that different from what i had originally since i still need to manually specify the "null":

if (value >= 0) value else { println("Warning"); null }

i guess i'll just have to deal with it/define an extension function if needed

thanks for the suggestions