is there a way, to make a method tailrecursive. wh...

# announcements

[thana]

is there a way, to make a method tailrecursive. when the return is nested in a return?

[karelpeeters]

Can you share the code?

[thana]

Sorry i meant the recursive step, not the return

[thana]

I c cannot share the code itself, but
in the end its traversing a tree where i calculate a value based on its children, so the pseudo code looks like:

fun caclculate(treeNode: TreeNode): Int {
  val baseValue = 10
  var returnValue;
  for (child: treeNode.Children) {
    returnValue += calculate(child) 
  }
return returnValue + baseValue;
}

[diesieben07]

That cannot work. Tail recursion is called that, because the recursive call must be the last thing in the function

[diesieben07]

Otherwise the recursion cannot be unrolled into a flat loop by the compiler

[thana]

yeah im aware of that, but i wonder i f there are some clever tricks to restructure the code to rget rid of it, that i am not aware of 😉

[diesieben07]

You can implement a Queue of nodes still to do. But that is effectively just implementing your own call stack.

[diesieben07]

Although most likely more lightweight

[than_]

general solution is to add an accumulator

tailrec fun calculate(treeNode: TreeNode, acc: Int){
// logic
return calculate(otherTreeNode, acc+resultOfLogic)
}

[thana]

oh an accumulator. thats clever. i'll check that. thank you!

[than_]

have fun 🙂