[Guido, re PEP 246]
Surely it would be a dramatic change, probably deeper than new-style classes and generators together.
[Alex Martelli]
Rarely does one catch Guido (or most any Dutch, I believe) in such a wild overbid. Heat getting to you?-)
Curiously, I don't think Guido was overstating his belief, but he's got his Python-User's Hat on there, not his Developer-of-Python Hat. While new-style classes cut deeply and broadly in the language implementation, most Python programmers can ignore them (the type/class split bit extension module authors the hardest, and life can be much more pleasant for them now). Protocol adaptation taken seriously would be a fundamental change in the Python Way of Life for users, from "just try it and see whether it works", to "you don't *have* to guess anymore". I think it would make a dramatic difference in the flavor of day-to-day Python programming -- and probably for the better, ignoring speed.