CODEWITHSUNDEEP
kotlin
Héctor
Héctor

Reputation: 26054

Is it possible to destructure data class' instance into class' properties?

I have a data class MyDataClass:

data class MyDataClass(val a: Int, val b: Int)

and a class MyClass with two properties. I want to destructure an instance of MyDataClass, so a and b are assigned to MyClass properties, instead of declare new variables:

class MyClass {

  val a: Int
  val b: Int

  init {
    val mdc = MyDataClass(1, 4)
    (a, b) = mdc //error
  }

}

Upvotes: 6

Views: 2224

Answers (2)

Biscuit
Biscuit

Reputation: 5247

Although destructuring declaration are only allowed for local you can still do something like this

class MyClass {

    val a: Int
    val b: Int

    init {
        val (a, b) = MyDataClass(1, 4)
        this.a = a
        this.b = b
    }
}

Upvotes: 4

Lovis
Lovis

Reputation: 10047

No, destructuring declarations are only allowed for local variables and lambda parameters.

Also, they are only used to create multiple local variables at once. So val (a, b) = mdc is allowed, but (a, b) = mdc is invalid syntax, even if a and b are not properties.

Upvotes: 9

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