Python中的闭包

x=44
def (func):
????return func()
import foo
def bar():
????x=13
????def hello():
????????return "hello %s" %x
????foo.callf(hello)
得到结果为 hello 13
在编写惰性求值的代码的时候，闭包是一个很好的选择
from urllib import urlopen 
????def page (url) : 
????????def get() : 
????????????大专栏  Python中的闭包 class="keyword">return urlopen (url).read()
????????return get 
>>>python=page("http://www.python.org") 
>>>jython=page( "http://www.jython.org") 
>>>python 
<function get at 0x9735f0>
>>>jython 
<function get at 0x9737f0>
>>>pydata=python() 
>>>jydata=jython() 
page()

def countdown(n):
????def next():
????????nonlocal n
????????r=n
????????n-=1
????????return r
????return next
next=countdown(10)
while True:
????v=next()
????if not v:break