如何在Python中设置顶级变量？

Question

假设我有一个脚本文件,如下所示:

foo = 1

def bar():
    return foo

# The Main function for this script.
def main(argv=None):
    foo = 2
    print bar()
    return

这打印1.有没有办法在main的脚本级别设置foo的值？

Answer 1

foo = 1

def bar():
    return foo

# The Main function for this script.
def main(argv=None):
    global foo
    foo = 2
    print bar()
    return

这是在python文档中.

Answer 2

def main(argv=None):
    global foo
    foo = 2
    print bar()
    return