python3.x 基礎三：裝飾器

裝飾器：本質是函數，用於裝飾其他函數，在不改變其他函數的調用和代碼的前提下，增加新功能

原則：

1.不能修改被裝飾函數的源代碼

2.不能修改被裝飾函數的調用方式

3.裝飾函數對於被裝飾函數透明

參考如下鏈接：

http://egon09.blog.51cto.com/9161406/1836763

實現裝飾器的需求：

1. 函數即“變量”，函數名指向內存中的函數體，加()表示調用
2. 高價函數，將函數當做參數傳遞給其他函數
3. 嵌套函數，在函數體內再定義函數

1.調用簡單的函數：

import time
def test1():
    time.sleep(1)
    print('in the test1')
test1()

output： 
in the test1

2.在不改變原來函數的定義和調用方式，增加計時功能

import time
def timmer(func):
    def warpper(*args,**kwargs):
        start_time=time.time()
        func()
        stop_time=time.time()
        print('the func run time is %s' %(stop_time-start_time))
    return  warpper

@timmer
def test1():
    time.sleep(1)
    print('in the test1')
test1()

output：
in the test1
the function  run time is -1.0007600784301758:

# /usr/bin/env python
# -*- coding: utf-8 -*-
# Author:Jenvid.yang
# def foo():
#     print('in the foo')
#     bar()
# foo()
# bar() 未定義，肯定會報錯

# def bar():
#     print('in the bar')
# def foo():
#     print('in the foo')
#     bar()
# foo()

# def foo():
#     print('in the foo')
#     bar()
# def bar():
#     print('in the bar')
# foo()
# 定義函數的時候，只是用函數名指向內存地址，只要函數執行步驟在函數定義之后即可，各函數間前后關系不影響

# def foo():
#     print('in the foo')
#     bar()
# foo()
# def bar():
#     print('in the bar')

總結1：定義函數的時候，只是用函數名指向內存地址，只要函數執行步驟在函數定義步驟之后即可，各函數間定義先后不影響，與變量定義先后一個道理

 

高階函數

1.把一個函數名當做實參傳給另外一個函數--實現裝飾器：不修改被裝飾函數下，給源代碼，也就是被裝飾函數增加新功能

2.返回值中包含函數名--實現裝飾器：不修改函數的調用方式

• 函數返回實參函數內存地址

def bar():
    print('in the bar')
def test1(func):
    print(func)
test1(bar)
print('分割線'.center(30,'-'))
def test2(func):
    return func
fff=test2(bar) # 將內存地址，也就是函數體，也就是test2返回值，賦值給一個變量
fff() # 變量加上()，表示調用
output：
<function bar at 0x7f5fa0a7d730>
-------------分割線--------------
in the bar

• 高階函數傳參方式實現源代碼bar沒有被更改，調用方式被更改了

import time
def bar():
    time.sleep(1)
    print('in the bar')
def test1(func):
    start_time=time.time()
    func()
    stop_time=time.time()
    print('the function run time is %s' % (stop_time-start_time))
test1(bar)
output：
in the bar
the function run time is 1.0011107921600342
#被調用函數原來調用方式是：bar()，函數體里面的內容也沒有更改
#新的函數是test1，調用的是test1()，改變了調用函數名，如果有生產線上已經在調用bar()，這種情況下意味着所有的調用bar函數的其他函數，都需要將bar改成test1

• 高階函數返回值方式實現函數調用方式不更改

import time
def bar():
    time.sleep(1)
    print('in the bar')
def test1(func):
    start_time=time.time()
    return func
    stop_time=time.time()
    print('the function run time is %s' % (stop_time-start_time))
bar=test1(bar)
bar()
output：
in the bar
# 高階函數返回內存地址實現調用方式不更改，但函數的新功能又沒加上

• 嵌套函數，在高階函數下，給新功能函數增加多一層函數嵌套

import time
def bar():
    time.sleep(1)
    print('in the bar')
def timmer(func):
    def test1():
        start_time=time.time()
        func()
        stop_time=time.time()
        print('the function run time is %s' % (stop_time-start_time))
    return test1  #返回test1的內存地址
bar=timmer(bar) #將bar函數地址作為實參傳遞給timmer函數的形參func，func將在嵌套函數test1里面進行調用
bar() #此時的bar其實是timmer函數地址，並不是原來的bar
output：
in the bar
the function run time is 1.0010881423950195

• 語法糖

import time
def timmer(func):
    def test1():
        start_time=time.time()
        func()
        stop_time=time.time()
        print('the function run time is %s' % (stop_time-start_time))
    return test1
# bar=timmer(bar)
@timmer  #只需要在被調用函數的前面用關鍵字符“@裝飾器函數”，既可以實現裝飾器效果
def bar():
    time.sleep(1)
    print('in the bar')
bar()
output：
in the bar
the function run time is 1.0011053085327148

import time
def timmer(func):
    def warpper():  #一般將裝飾器嵌套函數名命名為warpper  據說懂了這個可以解決90%的問題
        start_time=time.time()
        func()
        stop_time=time.time()
        print("the function  run time is %s:" %(start_time-stop_time))
    return warpper
@timmer  #這里還是相當於更改被裝飾函數的’變量名‘內存地址 bar=timmer(bar)
def bar():
    time.sleep(1)
    print('in the bar')
bar()

• 裝飾器參數傳值-被裝飾函數傳1個值

import time
def timmer(func):
    def warpper(name):
        start_time=time.time()
        func(name)
        stop_time=time.time()
        print("the function  run time is %s:" %(start_time-stop_time))
    return warpper
@timmer
def test1(name):
    time.sleep(1)
    print('in the test1 %s',name)
test1('alex')
output：
in the test1 %s alex
the function  run time is -1.0006732940673828:

• 裝飾器參數傳值-被裝飾函數傳2個值

import time
def timmer(func):
    def warpper(name,age):
        start_time=time.time()
        func(name,age)
        stop_time=time.time()
        print("the function  run time is %s:" %(start_time-stop_time))
    return warpper
@timmer
def test1(name,age):
    time.sleep(1)
    print('in the test1 name is %s,age is %d'%(name,age))
test1('alex',18)
output：
in the test1 name is alex,age is 18
the function  run time is -1.000108003616333:

• 裝飾器參數傳值-被裝飾函數傳n個值

import time
def timmer(func):
    # print('func timmer')
    def wrapper(*args,**kwargs):
        print('打印實參：',args,kwargs)
        start_time=time.time()
        func(*args,**kwargs)
        stop_time=time.time()
        print("the function  run time is %s:" % (stop_time-start_time))
    return wrapper
@timmer
# test1=timmer(test1)
def test1(name,age):
    time.sleep(1)
    print('in the test1 func, name is %s,age is %d' % (name,age))
test1('alex',18)

@timmer
# test1=timmer(test1)
def test2(name,age,sex,salary):
    time.sleep(1)
    print('in the test1 func, name is %s,age is %d,sex is %s,salary is %d' % (name,age,sex,salary))
test2('alex',18,'man',3000)
output：
打印實參： ('alex', 18) {}
in the test1 func, name is alex,age is 18
the function  run time is 1.0013768672943115:
打印實參： ('alex', 18, 'man', 3000) {}
in the test1 func, name is alex,age is 18,sex is man,salary is 3000
the function  run time is 1.0012915134429932:

• 試錯過程：

• import time
  def timmer(func):
      def warpper():
          # print('打印實參：',args,kwargs)
          start_time=time.time()
          func()
          stop_time=time.time()
          print("the function  run time is %s:" % (stop_time-start_time))
      return warpper
  @timmer #這里相當於test1=timmer(test1)=wrapper,test1加上參數相當於test1(name,age)=wrapper(name,age)
  def test1(name,age):
      time.sleep(1)
      print('in the test1 name is %s,age is %s'%(name,age))
  test1('alex',18)
  輸出如下：
  /usr/bin/python3.5 /root/PycharmProjects/S14/day04/bin/decoreate03.py
  Traceback (most recent call last):
    File "/root/PycharmProjects/S14/day04/bin/decoreate03.py", line 17, in <module>
      test1('alex',18)
  TypeError: warpper() takes 0 positional arguments but 2 were given
  
  Process finished with exit code 1
  step1：定義裝飾器函數體timmer
  step2：語法糖，調用裝飾器函數，准備裝飾下一行函數，返回內層嵌套函數變量warpper內存地址
  step3：定義函數體test1
  step4：調用函數test1，將test1作為實參，傳遞給裝飾器timmer
  step5：warpper函數調用，需要講test1的實參傳遞給wrapper，由於命名空間關系，test1的參數無法傳遞到warpper，func也無法獲得實參
  

• 給包裝函數warrper增加形參

• import time
  def timmer(func):
      def warpper(name,age):
          # print('打印實參：',args,kwargs)
          start_time=time.time()
          func()
          stop_time=time.time()
          print("the function  run time is %s:" % (stop_time-start_time))
      return warpper
  @timmer  #test1=timmer(test1)
  def test1(name,age):
      time.sleep(1)
      print('in the test1 name is %s,age is %s'%(name,age))
  test1('alex',18)
  輸出如下
  /usr/bin/python3.5 /root/PycharmProjects/S14/day04/bin/decoreate03.py
  Traceback (most recent call last):
    File "/root/PycharmProjects/S14/day04/bin/decoreate03.py", line 17, in <module>
      test1('alex',18)
    File "/root/PycharmProjects/S14/day04/bin/decoreate03.py", line 9, in warpper
      func()
  TypeError: test1() missing 2 required positional arguments: 'name' and 'age'
  這個解釋很明顯，func就是test1，缺少了2個位置參數，把func()改成func(name,age)即正確
  

 

• # /usr/bin/env python
  # -*- coding: utf-8 -*-
  # Author:Jenvid.yang
  import time
  def timmer(func): #func=test2
      def wrapper(*args,**kwargs):
          start_time=time.time()
          func(*args,**kwargs)
          stop_time=time.time()
          print('func run time is %s' %(stop_time-start_time))
      return wrapper
  
  @timmer
  def bar():
      time.sleep(1)
      print('in the bar')
  bar()
  @timmer  #test2=timmer(test2)=warpper  ->test2(name)=warpper(name)
  def test2(name):
      time.sleep(1)
      print('in the test2',name)
  test2('alex')

• 被裝飾函數如果帶有返回值的情況

import time
def timmer(func):
    # print('func timmer')
    def wrapper(*args,**kwargs):
        print('打印實參：',args,kwargs)
        start_time=time.time()
        func(*args,**kwargs)
        stop_time=time.time()
        print("the function  run time is %s:" % (stop_time-start_time))
    return wrapper
@timmer
# test1=timmer(test1)
def test1(name,age,address):
    time.sleep(1)
    print('in the test1 func, name is %s,age is %d,address is %s' % (name,age,address))
test1('alex',18,'nuber001')
# @timmer
# test1=timmer(test1)
def test3(name,age,sex,salary):
    time.sleep(1)
    # print('in the test1 func, name is %s,age is %d,sex is %s,salary is %d' % (name,age,sex,salary))
    return (name,age,sex,salary)
print(test3('alex',18,'man',3000))
輸出如下：
/usr/bin/python3.5 /root/PycharmProjects/S14/day04/decoreate02.py
打印實參： ('alex', 18, 'nuber001') {}
in the test1 func, name is alex,age is 18,address is nuber001
the function  run time is 1.0009291172027588:
('alex', 18, 'man', 3000)

Process finished with exit code 0
函數test1，沒有返回值，裝飾后正常輸出
函數test2，帶有返回值，沒有裝飾，打印了實參元組
如果test2裝飾后呢？

import time
def timmer(func):
    # print('func timmer')
    def wrapper(*args,**kwargs):
        print('打印實參：',args,kwargs)
        start_time=time.time()
        func(*args,**kwargs)
        stop_time=time.time()
        print("the function  run time is %s:" % (stop_time-start_time))
    return wrapper
@timmer
# test1=timmer(test1)
def test1(name,age,address):
    time.sleep(1)
    print('in the test1 func, name is %s,age is %d,address is %s' % (name,age,address))
test1('alex',18,'nuber001')
@timmer
# test1=timmer(test1)
def test3(name,age,sex,salary):
    time.sleep(1)
    # print('in the test1 func, name is %s,age is %d,sex is %s,salary is %d' % (name,age,sex,salary))
    return (name,age,sex,salary)
print(test3('alex',18,'man',3000))
輸出如下：
打印實參： ('alex', 18, 'nuber001') {}
in the test1 func, name is alex,age is 18,address is nuber001
the function  run time is 1.0010955333709717:
打印實參： ('alex', 18, 'man', 3000) {}
the function  run time is 1.0010552406311035:
None
帶有返回值的test2被裝飾后，變成了None，改變了原函數的輸出，這是不允許的

給包裝函數中的調用原函數增加賦值和返回值：

import time
def timmer(func):
    # print('func timmer')
    def wrapper(*args,**kwargs):
        print('打印實參：',args,kwargs)
        start_time=time.time()
        res=func(*args,**kwargs)  #用一個變量保存原函數輸出值
        stop_time=time.time()
        print("the function  run time is %s:" % (stop_time-start_time))
        return res #返回原函數結果給wrapper
    return wrapper
@timmer
# test1=timmer(test1)
def test1(name,age,address):
    time.sleep(1)
    print('in the test1 func, name is %s,age is %d,address is %s' % (name,age,address))
test1('alex',18,'nuber001')
@timmer
# test1=timmer(test1)
def test3(name,age,sex,salary):
    time.sleep(1)
    # print('in the test1 func, name is %s,age is %d,sex is %s,salary is %d' % (name,age,sex,salary))
    return (name,age,sex,salary)
print(test3('alex',18,'man',3000))
輸出如下：
打印實參： ('alex', 18, 'nuber001') {}
in the test1 func, name is alex,age is 18,address is nuber001
the function  run time is 1.0010664463043213:
打印實參： ('alex', 18, 'man', 3000) {}
the function  run time is 1.0010428428649902:
('alex', 18, 'man', 3000)

• 語法糖帶參數情況，index使用本地驗證，home使用ldap驗證，同一個裝飾器，如何實現不同的驗證方式？

• def deco(func):
      def wrapper(username,password):
          print('I am 包裝1')
          func(username,password)
          print('I am 包裝2')
      return wrapper
  @deco(auth_type='local')
  def index(username,password):
      print('welcome to index page',username)
  index('yzw','secret')
  @deco(auth_type='ldap')
  def home(username,password):
      print('welcome to home page',username)
  home('alex','secret')

   

• 再嵌套一層函數

• def auth(auth_type):
      def out_wrapper(func):
          def wrapper(username,password):
              if auth_type == 'local':
                  print('via local certification')
                  print('I am 包裝前')
                  func(username,password)
                  print('I am 包裝后')
              elif auth_type == 'ldap':
                  print('嘻嘻嘻嘻')
                  func(username, password)
                  print('via ldap certfication')
          return wrapper
      return out_wrapper
  @auth(auth_type='local')
  #1.全部不帶參數，相當於index=deco(index)
  #2.被裝飾函數帶參數，相當於index=deco(index)=wrapper ->index(args)=wrapper(args)
  #3.語法糖帶參數，就需要多嵌套一層外層函數，將語法糖的參數傳遞給這一外層函數
  def index(username,password):
      print('welcome to index page <local>',username)
  index('yzw','secret')
  @auth(auth_type='ldap')
  def home(username,password):
      print('welcome to home page <ldap>',username)
  home('alex','secret')
  輸出如下：
  /usr/bin/python3.5 /root/PycharmProjects/S14/day04/bin/decorate04.py
  via local certification
  I am 包裝前
  welcome to index page <local> yzw
  I am 包裝后
  嘻嘻嘻嘻
  welcome to home page <ldap> alex
  via ldap certfication
  
  Process finished with exit code 0
  
  

• #/usr/bin/env python
  #-*- coding: utf-8 -*-
  #Author:jenvid.yang
  def auth(auth_type):
      def out_wrapper(func):
          def wrapper(*args,**kwargs):
              if auth_type == 'local':
                  print('via local certification')
                  func(*args,**kwargs)
              elif auth_type == 'ldap':
                  print('via ldap certfication')
                  func(*args, **kwargs)
          return wrapper
      return out_wrapper
  @auth(auth_type='local')
  #1.全部不帶參數，相當於index=deco(index)
  #2.被裝飾函數帶參數，相當於index=deco(index)=wrapper ->index(args)=wrapper(args)
  #3.語法糖帶參數，就需要多嵌套一層外層函數，將語法糖的參數傳遞給這一外層函數
  def index(username,password):
      print('welcome to index page <local>',username)
  index('yzw','secret')
  @auth(auth_type='ldap')
  def home(username,password):
      print('welcome to home page <ldap>',username)
  home('alex','secret')

• # /usr/bin/env python
  # -*- coding: utf-8 -*-
  # Author:Jenvid.yang
  import time
  user,passwd='alex','abc123'
  def auth(auth_type):
      print('auth func:',auth_type)
      def outer_wrapper(func):
          def wrapper(*args,**kwargs):
              print('wrapper func args:',*args,**kwargs)
              if auth_type == 'local':
                  username=input('username:').strip()
                  password=input('password:').strip()
                  if user == username and passwd == password:
                      print('\033[32;1m user has passed authentication \033[0m')
                      res = func(*args,**kwargs)
                      print('xxxxx')
                      return res
                  else:
                      exit('\033[31;1m invalid username or password \033[0m')
              elif auth_type == 'ldap':
                  print('xxxx')
          return wrapper
      return outer_wrapper
  # @auth
  def index():
      print('welcome to index page')
  @auth(auth_type='local')  #home=wrapper()
  def home():
      print('welcom to home page')
      return ('from home')
  # 函數結果被改變
  @auth(auth_type='ldap')
  def bbs():
      print('welcome to bbs page')
  
  index()
  print(home()) # wrapper()
  bbs()