然后给大家介绍的是Wrapper(装饰器),使用广泛。python笔试,面试的话也会百分百问到的,基础和中级的知识储备还是必用的。

让我们开始。

先来一些基础相关知识

*args,**kwargs的区别def function(x,y,*args,**kwargs):    print(type(x))    print(args)            print(kwargs)    print(type(args))            print(type(kwargs))function(1,2,3,4,5,a=1,b=2,c=3)
     
      (3, 4, 5)            　　　　#*args返回的是数组{
    'a': 1, 'c': 3, 'b': 2}    #**kwargs返回的字典
      
       
      
     

正题开始

固定模板

装饰器:wrapper模板:def    装饰器名(func):                    #def 与 @之后的函数名称一致   调用函数func与ret=func(*args,**kwargs)内部函数一致    def wrapper(*args,**kwargs):         #def 与 return 之后的函数名称一致        ret = func(*args,**kwargs)                    return ret                       #return ret 与 ret=func(*args,**kwargs)一致    return wrapper@装饰器名def foo():    pass

import timedef timmer(fun1):    def wrapper(*args,**kwargs):        start_time=time.time()        res=fun1(*args,**kwargs)        stop_time=time.time()        print('run time is %s' %(stop_time-start_time))        return res    return wrapper@timmerdef foo():    time.sleep(3)    print('from foo')@timmerdef foo1():    time.sleep(5)    print('from foo1')foo()foo1()

 @wraps：避免被装饰函数自身的信息丢失

未添加@wraps

#-*- coding:utf-8 -*-def decorator(func):    def inner_function():        pass    return inner_function@decoratordef func():    passprint(func.__name__)#inner_function

添加@wraps

from functools import wrapsdef decorator(func):    @wraps(func)     def inner_function():        pass    return inner_function@decoratordef func():    passprint(func.__name__)#func#@wraps：避免被装饰函数自身的信息丢失

多个装饰器的同时使用

def makebold(f):    return lambda:''+f()+''def makeitalic(f):    return lambda:''+f()+''def makeitalic1(f):    return lambda:''+f()+''@makebold@makeitalic1@makeitalicdef say():    return 'hello'print(say())#hello#多个装饰器的执行顺序：是从近到远依次执行。

类装饰器

#类装饰器class Decorator(object):    def __init__(self, f):        self.f = f    def __call__(self):        print("decorator start")        self.f()        print("decorator end")@Decoratordef func():    print("func")func()'''decorator startfuncdecorator end'''

import timedef decorator(func):    def wrapper(*args,**kwargs):        start_time = time.time()        func(*args,**kwargs)        end_time = time.time()        print(end_time - start_time)    return wrapperclass Method(object):    @decorator     def func(self):        time.sleep(0.8)p1 = Method()p1.func() # 函数调用'''0.815999984741对于类方法来说，都会有一个默认的参数self，它实际表示的是类的一个实例，所以在装饰器的内部函数wrapper也要传入一个参数- me_instance(任意参数)就表示将类的实例p1传给wrapper，其他的用法都和函数装饰器相同。'''

较为复杂的多个装饰器 

import timedef deco01(func):    def wrapper(*args, **kwargs):        print("this is deco01")        startTime = time.time()        func(*args, **kwargs)        endTime = time.time()        msecs = (endTime - startTime)*1000        print("time is %d ms" %msecs)        print("deco01 end here")    return wrapperdef deco02(func):    def wrapper(*args, **kwargs):        print("this is deco02")        func(*args, **kwargs)        print("deco02 end here")    return wrapper@deco01@deco02def func(a,b):    print("hello，here is a func for add :")    time.sleep(1)    print("result is %d" %(a+b))if __name__ == '__main__':    f = func    f(3,4)'''this is deco01this is deco02hello,here is a func for add :result is 7deco02 end heretime is 1032 msdeco01 end here'''#多个装饰器执行的顺序就是从最后一个装饰器开始，执行到第一个装饰器，再执行函数本身。