CODEWITHSUNDEEP
kotlin
Robert MacLean
Robert MacLean

Reputation: 39260

Is it possible to implement the spread operator on other classes?

Is it possible to implement the spread operator on other classes in the same way you can with other operators like +, for example:

class Demo{
  operator fun plus(i:Int):Demo {
    ...
  }
}

Upvotes: 0

Views: 750

Answers (1)

Alexander Egger
Alexander Egger

Reputation: 5300

No you can`t. The spread operator is not matched by any function therefore it can not be overloaded in Kotlin.

When looking at the bytecode created by the compiler one can see, that vararg is compiled to an array. The spread operator just creates a copy of that array.

For example: 

fun test(vararg strings: String) {
}

fun main() {
    val params = arrayOf("1", "2")
    test(*params)
}

compiles to:

INVOKESTATIC java/util/Arrays.copyOf ([Ljava/lang/Object;I)[Ljava/lang/Object;
CHECKCAST [Ljava/lang/String;
INVOKESTATIC CoroutineTestKt.test ([Ljava/lang/String;)V

Upvotes: 1

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