Ian Kelly wrote:
I already mentioned this earlier in the thread, but a balanced binary tree might implement += as node insertion and then return a different object if the balancing causes the root node to change.
That would be a really bad way to design a binary tree implementation. What if there is another reference to the tree somewhere? It's still going to be referring to the old root object, and will have an incoherent view of the data -- partly old and partly new. If you're going to have a mutable tree, it needs to be encapsulated in a stable top-level object. -- Greg -- https://mail.python.org/mailman/listinfo/python-list
