having following function
fun functionOne(element: Int, func1: (index: Int) -> Unit) {
println("element=$element")
func1(element)
}
I can call it that way:
functionOne(element = 123, func1 = {index -> println("index: $index")})
no compilator complains
functionOne(123, {index -> println("index: $index")})
now compilator suggests Lambda argument should be moved out of parentheses
or
functionOne(123) { index -> println("index: $index") }
no complains
however, unless I don't get it right, this behavior is limited to exactly one lambda argument, that is having
fun functionTwo(element: Int, func1: (index: Int) -> Unit, func2: (index: Int) -> Unit) {
println("element=$element")
func1(element)
func2(element)
}
I can make a call like this
functionTwo(123, { index -> println("index: $index")}, { index -> println("index2: $index")})
but this one does not compile
functionTwo(456) {index -> println("index: $index"} { index -> println("index2: $index")})
can you please confirm that or let me know to move lambda arguments out of parentheses
thanks!
According to the documentation, only trailing lambdas can be placed outside the parenthesis:
Passing trailing lambdas
According to Kotlin convention, if the last parameter of a function is a function, then a lambda expression passed as the corresponding argument can be placed outside the parentheses:
val product = items.fold(1) { acc, e -> acc * e }
Such syntax is also known as trailing lambda.
If the lambda is the only argument in that call, the parentheses can be omitted entirely:
run { println("...") }
This implies that you can not move the second-to-last lambda expression outside of the parenthesis, and thus that you cannot move multiple lambda expressions out of the parenthesis.