python装饰器的作用，我是这么理解的，
比如本来已经有几个写好的函数，这几个函数的返回值都是list，现在我想要它们都返回str型的值，一个个改函数太累，也容易出错，装饰器能解决这样的问题，它能对n个函数进行编程
def square(func):
#返回平方
def _deco(a, b):
rtn = func(a, b)
return rtn * rtn
return _deco
@square
def my_add(a, b):
return a+b
print my_add(1,2)
# 原来的几个返回list的函数，具体干嘛不管，示例用
def even_element(lst):
return [n for n in lst if n%2 == 0]
def odd_element(lst):
return [n for n in lst if n%2 == 1]
def link_list(lst1, lst2):
l = deepcopy(lst1)
l.extend(lst2)
return l
a = range(5)
b = range(10)
print even_element(a)
print odd_element(a)
print link_list(a, b)
from copy import deepcopy
# 用装饰器
def list_to_str(func):
def wrapper(*args, **kwargs):
rtn_lst = [str(n) for n in func(*args, **kwargs)]
return ','.join(rtn_lst)
return wrapper
# 此时这些函数都返回str型
@list_to_str
def even_element(lst):
return [n for n in lst if n%2 == 0]
@list_to_str
def odd_element(lst):
return [n for n in lst if n%2 == 1]
@list_to_str
def link_list(lst1, lst2):
l = deepcopy(lst1)
l.extend(lst2)
return l
a = range(5)
b = range(10)
print even_element(a)
print odd_element(a)
print link_list(a, b)
带参数的装饰器
# encoding: utf-8
import time
'''
现实函数运行时间
参数run_times为被测函数运行次数
'''
def time_func(run_times):
def _time_func(func):
def wrapper(*args, **kwargs):
t1 = time.time()
for n in xrange(run_times):
rtn = func(*args, **kwargs)
t2 = time.time()
print t2 - t1
return rtn
return wrapper
return _time_func
@time_func(10000)
def addd(a, b):
return a+b
print addd(1,2)