On Mon, Jun 29, 2020, at 04:51, Stephen J. Turnbull wrote:
Of course, we may prefer a boolean return, despite the general rule about returning elements. I'm single-threaded, and so agnostic on that. :-) But if it turns out that somebody *wants* to check "2 is 2.0", this .add_unique can serve both purposes.
I don't think this is a good idea - for one thing, an element return means you can't handle, or have to handle specially, None being in a set.
If we want a way to check the type or identity of an item in a set, I think it would be best to add another method to access the item. Or an operator - i.e. check if type(set[2]) is int or float, or whatever it is you want. I did once write a way to do that in O(1) time in unmodified python [abusing the __eq__ method of a custom class to smuggle the value out] as an exercise, incidentally, and it seemed to work fine.