rebinding built-ins is quite a deprecated as well as a rare practice in Python. In Ruby, it strikes me as major — just like the too powerful macro facilities of other languages (such as, say, Dylan) present similar risks in my own opinion (I do hope that Python never gets such a powerful macro system, no matter the allure of “letting people define their own domain-specific little languages embedded in the language itself” — it would, IMHO, impair Python’s wonderful usefulness for application programming, by presenting an “attractive nuisance” to the would-be tinkerer who lurks in every programmer’s heart).
