装饰器

Posted 2022-05-12 beichen123

装饰器

定义:

用来装饰的工具

在不改变源代码及调用方式的基础上额外增加新的功能

开放封闭原则:

扩展是开放的(增加新功能)

修改源码是封闭的(修改已经实现的功能)

版一:

import time
start_time = time.time()
def func():
    time.sleep(2)
    print("asdf")
func()
print(time.time() - start_time)

start_time = time.time()
def foo():
    time.sleep(3)
    print("qwer")
foo()
print(time.time() - start_time)

版二:

def times(f):
    start_time = time.time()
    f()
    print(time.time() - start_time)

def foo():
    time.sleep(3)
    print("asdf")

s = foo
foo = times
foo(s)

版三(初识版装饰器):

def times(f):
    def inner():
        start_time = time.time()
        f()
        print(time.time() - start_time)
    return inner
def foo():
    time.sleep(1)
    print("asdf")
foo = times(foo)
foo()

版四(第二版装饰器):

def wrapper():
    def inner():
        print(1)
    return inner
print(wrapper()())


def wrapper(f):                 
    def inner():                
        f()                     
    return inner                                           
def func():                     
    print("123456")             
func = wrapper(func)            
func()                          

low版

import time
def wrapper(f):
    def inner(*args,**kwargs):
        start_time = time.time()
        f(*args,**kwargs)
        print(time.time() - start_time)
    return inner
def func(*args,**kwargs):
    print(f"这是args,kwargs函数")
    time.sleep(2)
func = wrapper(func)
func("alex","wusir")

高级版:

import time
def wrapper(f):
    def inner(*args,**kwargs):
        start_time = time.time()
        f(*args,**kwargs)
        print(time.time() - start_time)
    return inner
@wrapper
def func(*args,**kwargs):
    print(f"这是args,kwargs函数")
    time.sleep(2)
@wrapper
def foo(*args,**kwargs):
    print(f"这是args,kwargs函数,123456")
    time.sleep(3)
func("alex","ahfe")
foo("alex1","faikewfhn")

标准版:

def func(a):  #a是要被装饰的函数名
    def foo(*args,**kwargs):
        "装饰之前的操作"
        ret = a(*args,**kwargs)
        "装饰之后的操作"
        return ret
    return foo
@func
def f1(*args,**kwargs):
    print(f"这是一个args")
    return "我可以返回了"
f1(1,2,3,34,4,5)

语法糖

语法糖必须放在被装饰的函数正上方

@wrapper  就等于   func = wrapper(func)
@wrapper  就等于   foo = wrapper(foo)