Out of curiosity, I ran: globals().clear()
in the interactive interpreter. It broke much more than I expected! Built-ins were no longer available, and import stopped working. I expected that global variables would be all lost, but built-ins would remain, since they don't live in the global namespace. I was wrong: >>> globals().clear() >>> x = len([]) Traceback (most recent call last): File "<stdin>", line 1, in <module> NameError: name 'len' is not defined The reason, I think, is that CPython has a special __builtins__ global variable that the interpreter uses to access built-in functions. What *appears* to be happening is that if that __builtins__ global is missing, CPython can not access the built-ins. (Supporting this interpretation: IronPython, like CPython, has a __builtins__ global, and behaves the same when the globals() are cleared. Jython, which does not have a __builtins__ global, does not.) Well that's okay, I thought to myself, I'll just import the built-in functions: >>> from builtins import len # use '__builtin__' in Python 2 Traceback (most recent call last): File "<stdin>", line 1, in <module> ImportError: __import__ not found Oops. So, with no built-ins available, import no longer works. That makes things rather tricky. Obviously the easiest way to recover is to exit the current session and restart it, but as a challenge, can we recover from this state? -- Steven -- https://mail.python.org/mailman/listinfo/python-list
