详解python装饰器的实例教程

Python中的装饰器是你进入Python大门的一道坎，不管你跨不跨过去它都在那里。Python中的装饰器的概念经常会让人搞得一头雾水,所以今天就好好来分析一下python中的装饰器

x = 1
def funx():
  x = 10
  print(x) # 打印出10

funx()
print(x) # 打印出1 

x = 1
def funx():
  print(x) # 打印出1

funx()
print(x) # 打印出1

x = 1
def funx():
  def func1():
    print(x) # 打印出1
  func1()

funx()
print(x) # 打印出1 

def delete(ps):
  import os
  filename = ps[-1]
  delelemetns = ps[1]
  with open(filename, encoding='utf-8') as f_read,    open('tmp.txt', 'w', encoding='utf-8') as f_write:
    for line in iter(f_read.readline, ''):
      if line != '\n': # 处理非空行
        if delelemetns in line:
          line = line.replace(delelemetns,'')
        f_write.write(line)
  os.remove(filename)
  os.rename('tmp.txt',filename)

def add(ps):
  filename = ps[-1]
  addelemetns = ps[1]
  with open(filename, 'a', encoding='utf-8') as fp:
    fp.write("\n", addelemetns)

def modify(ps):
  import os
  filename = ps[-1]
  modify_elemetns = ps[1]
  with open(filename, encoding='utf-8') as f_read,       open('tmp.txt', 'w', encoding='utf-8') as f_write:
    for line in iter(f_read.readline, ''):
      if line != '\n': # 处理非空行
        if modify_elemetns in line:
          line = line.replace(modify_elemetns, '')
        f_write.write(line)
  os.remove(filename)
  os.rename('tmp.txt', filename)


def search(cmd):
  filename = cmd[-1]
  pattern = cmd[1]
  with open(filename, 'r', encoding="utf-8") as f:
    for line in f:
      if pattern in line:
        print(line, end="")
    else:
      print("没有找到")

dic_func ={'delete': delete, 'add': add, 'modify': modify, 'search': search}

while True:
  inp = input("请输入您要进行的操作:").strip()
  if not inp:
    continue
  cmd_1 = inp.split()
  cmd = cmd_1[0]
  if cmd in dic_func:
    dic_func[cmd](cmd_1)
  else:
    print("Error") 

def outer():
  def inner():
    pass
  return inner

s = outer()
print(s)

###### 

输出 结果为####### <function outer.<locals>.inner at 0x000000D22D8AB8C8>

def index():
  print("index func")

def outer(index):
  s = index
  s()
  
outer(index)

###### 

输出结果######### index func

def outer():
  def inner():
    print("inner func excuted")
  inner() # 调用执行inner()函数
  print("outer func excuted")
outer() # 调用执行outer函数

#### 

输出 结果为########## inner func excuted outer func excuted

x = 1
def outer():
  def inner():
    print("x=%s" %x) # 引用了一个非inner函数内部的变量
    print("inner func excuted")
  inner() # 执行inner函数
  print("outer func excuted")

outer()
##### 

输出结果######## x=1 inner func excuted outer func excuted

def outer():
  x = 1
  def inner():
    print("x=%s" %x)
    print("inner func excuted")
  inner()
  print("outer func excuted")

outer()

##### 

输出结果######### x=1 inner func excuted outer func excuted

def outer():
  x = 1
  def inner():
    print("x=%s" %x)
    print("inner func excuted")
  print("outer func excuted")
  return inner # 返回内部函数名
  
outer() 

def outer():
  x = 1
  y = 2

  def inner():
    print("x= %s" %x)
    print("y= %s" %y)

  print(inner.closure)
  return inner

outer()

###### 

输出结果####### (<cell at 0x000000DF9EA965B8: int object at 0x000000006FC2B440>, <cell at 0x000000DF9EA965E8: int object at 0x000000006FC2B460>)

from urllib.request import urlopen

def index(url)
  def get()
    return urlopen(url).read()
  return get

python = index("http://HdhCmsTestpython.org") # 返回的是get函数的地址
print(python()) # 执行get函数《并且将返回的结果打印出来
baidu = index("http://HdhCmsTestbaidu测试数据")
print(baidu()) 

import time, random

def index():
  time.sleep(random.randrange(1, 5))
  print("welcome to index page") 

import time, random

def outer(func): # 将index的地址传递给func
  def inner():
    start_time = time.time()
    func()  # fun = index 即func保存了外部index函数的地址
    end_time = time.time()
    print("运行时间为%s"%(end_time - start_time))
  return inner # 返回inner的地址

def index():
  time.sleep(random.randrange(1, 5))
  print("welcome to index page")

index = outer(index) # 这里返回的是inner的地址，并重新赋值给index

index() 

def outer(func): # 将index的地址传递给func
  def inner(*args, **kwargs):
    start_time = time.time()
    func(*args, **kwargs)  # fun = index 即func保存了外部index函数的地址
    end_time = time.time()
    print("运行时间为%s"%(end_time - start_time))
  return inner # 返回inner的地址 

def timmer(func):
  def wrapper(*args,**kwargs):
    start_time = time.time()
    res=func(*args,**kwargs) #res来接收home函数的返回值
    stop_time=time.time()
    print('run time is %s' %(stop_time-start_time))
    return res 
  return wrapper

def home(name):
  time.sleep(random.randrange(1,3))
  print('welecome to %s HOME page' %name)
  return 123123123123123123123123123123123123123123 

import time
import random

def timmer(func):
  def wrapper():
    start_time = time.time()
    func()
    stop_time=time.time()
    print('run time is %s' %(stop_time-start_time))
  return wrapper
def auth(func):
  def deco():
    name=input('name: ')
    password=input('password: ')
    if name == 'egon' and password == '123':
      print('login successful')
      func() #wrapper()
    else:
      print('login err')
  return deco

@auth  # index = auth(timmer(index))         
@timmer # index = timmer(index)
def index():
 
  time.sleep(3)
  print('welecome to index page')

index() 

　　实验结果表明,多个装饰器装饰一个函数,其执行顺序是从下往上。

　　关于装饰器，还有一些高级用法,有兴趣的可以自己研究研究。

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