CODEWITHSUNDEEP
kotlin
ssuukk
ssuukk

Reputation: 8410

Check if function is empty in Kotlin

I have some callback that has a parameter defined like this:

val getMoreFunction : (() -> FSDirResult)? = null

Nullable, because I need to know if the function is actually defined. But I feel it's bad. I'd rather pass {} instead of null to my callbacks. So is there a way to determine if empty function was passed?

Upvotes: 3

Views: 3089

Answers (1)

miensol
miensol

Reputation: 41678

Ideally you would have a default parameter that can be called i.e.:

fun saneDefault(getMoreFunction: (() -> String) = { "" }): Boolean {
    val result = getMoreFunction()
    return result.isEmpty()
}

However if you really, really, really need to know if the argument was passed you can store the default parameter value like so:

private val DEFAULT = { throw UnsupportedOperationException("this shouldn't be called") }

fun isDefaultPassed(getMoreFunction: (() -> String) = DEFAULT): Boolean {
    if(getMoreFunction == DEFAULT){
        return true
    }
    return false
}

Upvotes: 4

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