Bruce Leban wrote:
However, there is an implementation complication due to the way variable scoping works in Python: if a variable is left unbound in the function locals, then references to that variable name would pick up the global if it exists
No, it wouldn't: Python 2.3 (#1, Aug 5 2003, 15:52:30) [GCC 3.1 20020420 (prerelease)] on darwin Type "help", "copyright", "credits" or "license" for more information.
def f(): ... print x ... x = 0 ... f() Traceback (most recent call last): File "<stdin>", line 1, in ? File "<stdin>", line 2, in f UnboundLocalError: local variable 'x' referenced before assignment
Python already has the machinery to make this work. All that's needed is a way to leave parameters unbound, and a syntax for asking "Would I get a NameError if I were to refer to this name now?" Perhaps something like def f(x?): if x?: ... -- Greg