When property access

[Wasabi375]

You could use

when {
  myDoor.isOpen -> ...
  myDoor.isClosed -> ...
  myDoor.isWooden -> ...
}

Also you might be interested in this discussion about adding it to when. When desperately needs `it`
But I think the closest solution to your problem would be

myDoor.apply {
  when{
    isOpen   -> ...
    isClosed -> ...
    isWooden -> ...
  }
}