Python automation _day4_ decorator review and decorator advanced

---Restore content begins---

Definition of a closure: an inner function references a variable of an outer function

Application of Closures: Decorators

Why is there a decorator: a decorator can add functions before and after the original function without changing the way the original function is called

#Advanced decorator, applying a new function can globally control whether all decorators take effect. 
import time
FLAG = True
def outer(flag):
    def timmer(f):
        def inner(*args,**kwargs):
            if flag == True:
                start_time = time.time()
                ret = f (* args, ** kwargs)
                end_time = time.time()
                print(end_time - start_time)
            else: 
                ret = f (* args, ** kwargs)
             return ret
         return inner
     return timmer

@outer(FLAG) # func = timmer(func)
def func(a,b):
    print('begin func,a',a)
    time.sleep(0.3)
    print('end func,b',b)

func(1,2)

#Decorator login log 
login_info = { ' alex ' :False}
 def login(func):
     def inner(name):
         if login_info[name] != True:
            user = input('user : ')
            pwd = input('pwd : ')
            if user == 'alex' and pwd == 'alex123':
                login_info[name] = True
            if login_info[name] == True:
                ret = func(name)
                return ret
    return inner
@login
def index(name):
    print('welcome %s to index' %name)

index('alex')

#Multiple decorators decorate a function, you need to put the decorator that executes first in it to execute first. 
1  def wrapper1(func):
 2      def inner():
 3          print  ' w1,before ' 
4          func()
 5          print  ' w1,after ' 
6      return inner
 7  
8  def wrapper2(func):
 9      def inner():
 10          print  ' w2,before ' 
11          func()
 12          print  ' w2,after ' 
13      return inner
 14  
15 @wrapper2
16 @wrapper1
17 def foo():
18     print 'foo'
19 
20 foo()
21 
22 运行结果：
23 w2,before
24 w1,before
25 foo
26 w1,after
27 w2,after