Python—装饰器

装饰器

1.普通函数

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

2.在函数前后添加功能

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()

3.使用装饰器

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()

4.装饰带参数的函数

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")

5.装饰动态参数的函数

#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")

6.装饰含有返回值的函数

#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

7.装饰器实现登录验证简单原理

def login():
    name =raw_input("输入用户名：")
    if name == "zhangsan":
        return  True
    else:
        return False
def mywork(func):
    def inner(*args,**kwargs):
        lo_login = login()
        if not lo_login:    #如果login()返回的是False
            return "用户名错误!"
        aa=func(*args,**kwargs)
        return aa
    return inner
@mywork
def a3(arg1,arg2):
    print 'i am zhangsan',arg1,arg2
    li=[1,2,3,4,5,6]
    return li
list=a3("参数1","参数2")    #list等于inner的返回值
print(list)

8.多个装饰器装饰一个函数

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
'''

9.装饰器加参数

#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