A modern programming language that makes developers happier.

kotlinlang

image.png

hi, I was reading about the destructuring declarations, and I came across this. can anyone explain please what this means? marked with operator keyword where? i can use component function without marking them with operator

You could theoretically have a function called `component1` without it being an `operator fun`, and hence it wouldn't get the spiffy syntax. This applies to all other operators I believe

`operator` functions in Kotlin are functions with special meaning. You can use operator functions to allow special behaviour which underneaths calls those functions. For example, when you use `+` sign on two lists to get new list containing all contents from both input lists, `operator fun <T> Collection<T>.plus` is called underneath.  `operator componentN` functions can be used for destructuring classes.

Consider following example:
```class Foo(
    val firstProp: String,
    val secondProp: Int
) {
    operator fun component1() = firstProp
    operator fun component2() = secondProp
    operator fun component3() = "$firstProp$secondProp"
}

class Bar(
    val firstProp: String,
    val secondProp: Int
) {
    fun component1() = firstProp
    fun component2() = secondProp
    fun component3() = "$firstProp$secondProp"
}

fun main() {
    val foo = Foo("one", 1)
    val (firstFooProp, secondFooProp, fooComponent3) = foo // destructuring via calling componentN functions implicitly

    val bar = Bar("two", 2)

    val (firstBarProp, secondBarProp, barComponent3) = bar // compilation error, implicit destructuring not possible due to lack of operator component functions
}```

thanks for all the answers! i really appreciate it)

<@U02Q05JJF7S> so i cant use operator in data class?  then is there a way to override data class component functions?

You can use your own operator functions in data classes (ie. get, plus, minus etc), but you cannot override implicitly implemented componentN functions for them