can someone help me with generics? lets say I alre...

# getting-started

[Michał Kalinowski]

can someone help me with generics? lets say I already overload Number operators and now I want make generics Point that will also overload operators based on Number, f.e result of Point<Float> + Point<Float> should be Point<Float> but recently is Point<in Float> :<

data class Point<Unit : Number>(val x: Unit, val y: Unit, val z: Unit) {
  operator fun plus(increment: Point<Unit>): Point<in Unit> {
    return Point(x + increment.x, y + increment.y, z + increment.z)
  }

  operator fun minus(increment: Point<Unit>): Point<in Unit> {
    return Point(x - increment.x, y - increment.y, z - increment.z)
  }

  operator fun times(increment: Point<Unit>): Point<in Unit> {
    return Point(x * increment.x, y * increment.y, z * increment.z)
  }

  operator fun div(increment: Point<Unit>): Point<in Unit> {
    return Point(x / increment.x, y / increment.y, z / increment.z)
  }
}

[Dico]

That's the type you're indicating expressly to be returned by your operators. Remove in from the type declarations and it should work.

[Michał Kalinowski]

then it will return Point<Number> not an Point<Float>

[Dico]

It will return Point<Unit> as indicated

[Dico]

You probably shouldn't name your type parameter Unit, btw

[StavFX]

I guess it would also depend on how you defined the Number operators