python之装饰器

转自：http://www.cnblogs.com/Eva-J/articles/7194277.html

1、装饰器函数的固定格式

def wrapper(func):
    def inner(*args,**kwargs):
        '''执行函数之前要做的'''
        re = func(*args,**kwargs)
        '''执行函数之后要做的'''
        return re
    return inner

举例

import time
def timer(func):
    def inner(*args,**kwargs):
        start = time.time()
        re = func(*args,**kwargs)
        print(time.time() - start)
        return re
    return inner

@timer   #==> func2 = timer(func2)
def func2(a):
    print('in func2 and get a:%s'%(a))
    return 'fun2 over'

func2('aaaaaa')
print(func2('aaaaaa'))

2、带参数的装饰器函数

def outer(flag):
    def timer(func):
        def inner(*args,**kwargs):
            if flag:
                print('''执行函数之前要做的''')
            re = func(*args,**kwargs)
            if flag:
                print('''执行函数之后要做的''')
            return re
        return inner
    return timer

@outer(False)
def func():
    print(111)

func()

3、多个装饰器装饰同一个函数

def wrapper1(func):
    def inner():
        print('wrapper1 ,before func')
        func()
        print('wrapper1 ,after func')
    return inner

def wrapper2(func):
    def inner():
        print('wrapper2 ,before func')
        func()
        print('wrapper2 ,after func')
    return inner

@wrapper2
@wrapper1
def f():
    print('in f')

f()

显示如下：

wrapper2 ,before func
wrapper1 ,before func
in f
wrapper1 ,after func
wrapper2 ,after func