Kotlin - Pass array of functions as argument to function

Question

I have this function that (theoretically) accept an array of functions as argument.

fun execute(afterDay: Long, listeners: Array<(List<String>) -> Unit>)

In the client class I trying to call this execute method and pass functions as parameter:

fun updateMovies(ids: Array<String>){

}

fun getNewIds() {
    GetImdbIds(kodein).execute(daysBack.toEpochDay(), [::updateMovies])
}

But it doesn't compiles.

What I'm doing wrong?

the error:

Error:(29, 59) Kotlin: Type inference failed. Expected type mismatch: inferred type is Array<KFunction1<@ParameterName Array<String>, Unit>> but Array<(List<String>) -> Unit> was expected
Error:(29, 59) Kotlin: Unsupported [Collection literals outside of annotations]

he said 'unresolved reference' but I realized the function should be declared before. Now the error is: Error:(29, 59) Kotlin: Type inference failed. Expected type mismatch: inferred type is Array<KFunction1<@ParameterName Array<String>, Unit>> but Array<(List<String>) -> Unit> was expected Error:(29, 59) Kotlin: Unsupported [Collection literals outside of annotations] — alexpfx
– alexpfx, Commented Jan 25, 2019 at 0:39

Todd · Accepted Answer · 2019-01-25 00:54:25Z

5

I got this to work by making two changes.

First, your updateMovies function as written takes an Array<String>, when your listeners wants functions that take List<String>. So, we can make this change:

fun updateMovies(ids: List<String>) {
    TODO()
}

Next, if you create your array of function references using arrayOf() instead of attempting an illegal array literal, this should compile:

GetImdbIds(kodein).execute(1L, arrayOf(::updateMovies))

answered Jan 25, 2019 at 0:54

Todd

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