The problem with the visitor pattern is that it hides the traversal which can be good for some things but then lead to weird bugs (e.g. imagine walking a tree w

The problem with the visitor pattern is that it hides the traversal which can be good for some things but then lead to weird bugs (e.g. imagine walking a tree with a buffer in the visitor, then the thing that runs your visitor runs the nodes more than you expect and so on) e.g. I've seen bad code slip past a compiler because the visitor didn't realize it was being run on every node in the tree so it never actually found the pattern it was trying to match.