$python用装饰器实现一个计时器

import time
from functools import wraps

# 定义装饰器
def fn_timer(function):
@wraps(function)
def function_timer(*args,**kwargs):
t0 = time.time()
result = function(*args,**kwargs)
t1 = time.time()
print '[finished {func_name} in {time:.2f}s]'.format(func_name = function.__name__,time = t1 - t0)
return result
return function_timer

# 使用装饰器来计时
@fn_timer
def download(url):
# 模拟下载3秒
print 'start to download from {0}...'.format(url)
time.sleep(3)
print 'download finished!'

download('www.baidu.com')

start to download from www.baidu.com...
download finished!
[finished download in 3.00s]