Python—装饰器

#简单的函数和调用
def a1():
print("i am zhangsan")
def a2():
print("i am lisi")
a1()
a2()

def inner(func):
print("添加1")
func()
print("添加2")
return func
def a1():
print("i am zhangsan")
def a2():
print("i am zhangsan")

a1=inner(a1)
a1()
a2=inner(a2)
a2()

def mywork(func):
def inner():
print("添加1")
func()
print("添加2")
return inner
@mywork     # @mywork就等于a1=mywork(a1)
def a1():
print("i am zhangsan")

a1()
#执行时@mywork会把他下面的函数当成mywork函数的参数既mywork(a1)，然后在函数inner里执行，inner内func()=a1()

def mywork(func):
def inner(arg):
print("添加1")
func(arg)
print("添加2")
return inner
@mywork
def a1(arg):
print 'i am zhangsan',arg

a1("参数1")

#合并无参，有参，多参  可以装饰含有N个参数的函数
def mywork(func):
def inner(*args,**kwargs):
print("添加1")
func(*args,**kwargs)
print("添加2")
return inner
@mywork
def a1():
print 'i am zhangsan'
@mywork
def a2(arg):
print 'i am zhangsan',arg
@mywork
def a3(arg1,arg2):
print 'i am zhangsan',arg1,arg2
a1()
a2("参数1")
a3("参数1","参数2")

#装饰含有返回值的函数
def mywork(func):
def inner(*args,**kwargs):
print("添加1")
aa=func(*args,**kwargs)
print("添加2")
return aa
return inner
@mywork
def a3(arg1,arg2):
print 'i am zhangsan',arg1,arg2
li=[1,2,3,4,5,6]
return li   #返回一个列表

list=a3("参数1","参数2")    #list等于inner的返回值
print(list)
#li列表是a3的返回值，所以给在inner函数里执行的func()赋给aa，在通过inner的返回值就能拿到列表

def newwork1(func):
def inner():
print("newwork1前")
func()
print("newwork1后")
return inner
def newwork2(func):
def inner():
print("newwork2前")
func()
print("newwork2后")
return inner

@newwork2
@newwork1
def f1():
print 'i am zhangsan'
f1()
'''
输出结果：
newwork1前
newwork2前
i am zhangsan
newwork2后
newwork1后
'''

#3层装饰器
def Filter(a1,a2):
def outer(func):
def wrapper(request,kargs):
print(a1)
result=func(request,kargs)
print(a2)
return result
return wrapper
return  outer
aa=11
bb=22
@Filter(aa,bb)
def Index(request,kargs):
print request,kargs

Index("zhangsan","lisi")
#@Filter(aa,bb)会先执行Filter(aa,bb)函数，获取到返回值outer后拼接成@outer，之后就变成普通的装饰器了
#wrapper函数内可以使用a1,a2,request,kargs 4个参数