Using a function to define itself?

[RossKen]

I have been trying to figure out what xgboostExplainer does under the hood and came across something strange (to my eyes anyway) when looking at the definition of findLeaves.R.

I can't work out:

1. why findLeaves() is used in the definition of findLeaves() (see line11)
2. how you can have three parameters of findLeaves() (see line 11) when it only has two by the definition being created. What does the with = FALSE part do?

Any help with either of these queries would be really appreciated!

[areeves87]

1. This is called a recursive function. They are useful for searching data structures with a lot of branches, such as a decision tree. There's nothing wrong with this approach although I don't know enough about this stuff to comment whether it could be improved.