Is there a nicer way to write this: ```val resultOrNull = firstAttemptOrNull() ?: run { if (some...

# codereview

[Mark]

Is there a nicer way to write this:

val resultOrNull = firstAttemptOrNull() ?: run {
    if (someConditionMet()) {
        secondAttemptOrNull()
    } else {
        null
    }
}

[dfriehs]

you could remove the run block (and consider a when block instead of if):

val resultOrNull = firstAttemptOrNull() ?: when {
    someConditionMet() -> secondAttemptOrNull()
    else -> null
}

[Joel]

firstAttemptOrNull() ?: secondAttemptOrNull()?.takeIf { someConditionMet() } downside is that it will run secondAttemptOrNull even if someConditionMet is false and then drop result on the floor. Unsure if there's a helper that runs the conditional first, like an if statement that runs a lambda.

[Joel]

firstAttemptOrNull() ?: if (someConditionMet()) secondAttemptOrNull() else null is also valid

[Mark]

How about declaring a simple top-level fun:

inline fun <R> otherwiseIf(condition: Boolean, block: () -> R): R? = if (condition) {
    block()
} else {
    null
}

And then we can do:

val resultOrNull = firstAttemptOrNull()
    ?: otherwiseIf(someConditionMet) {
        secondAttemptOrNull()
    }

[Joel]

You could, but it looks so much like a normal if I'd have to question if we're only doing it because we can 🙂

[Joel]

I've done like someConditionMet().ifTrue { secondAttemptOrNull() } but have never been happy with how it feels. I wish there were a nullable if statement syntax built-in.

[Joel]

firstAttemptOrNull() ?: if? (someConditionMet()) secondAttemptOrNull() would be sweet, and parallel features such as as?

[Mark]

Yeah I agree. The big drawback is it opens the question “how does otherwiseIf()/ifTrue() actually work” so make the code more difficult to read in some sense.

[Joel]

I have orElse in my codebase because it reads nicely, but I can't think of good syntax for the inverse that is meaningfully different from if. i.e. thisThingIsValid.orElse { doSomething() }

[Mark]

ifTrue would be a much better name for my otherwiseIf function of course!