Python 11th days, dnf 11th sets of sky Sets

Python 11th days, dnf 11th sets of sky Sets

Start learning the second module:

Decorator:

Description:

Decorator principles:

1. the source code of the decorated function cannot be modified.

2. The caller cannot modify the decoration function

 

Decorator:

Higher-order functions + nested functions = decorator

Higher-order functions:

Type I: a function that uses a function as a real parameter. It can be called a high-order function.

　　　　　　　　

1 def fun_1 (fun_2): # fun_1 is a high-order function 2 print ('1') 3 fun_2 () 4 5 def fun_2 (): 6 print ('2 ') 7 8 fun_1 (fun_2)

 

Type II: A function whose return value contains the function name, also known as a higher-order function

　　　　　　

Def fun_3 (fun): # fun_3 is the high-order function print ('3') return fundef fun_4 (): print ('4') # fun_3 (fun_4 )() # Run fun = fun_3 (fun_4) directly for the returned value # assign the returned value to a variable fun () # Call a function.

 

Nested functions:

Define a new function in a function. This function is called a nested function.

　　　　

1 def fun_5 (): # fun_5 is the nested function 2 print ('5') 3 def fun_5_1 (): 4 print ('5. 1') 5 6 fun_5 ()

The simplest Decoration:

1 def fun_2 (fun): # input fun_1 function 2 def function (): 3 4 fun () 5 print ('in the fun_2 ...... ') # Add new content 6 7 return function 8 9 @ fun_2 # decorate fun _! Equivalent to fun_1 = fun_2 (fun_1) 10 def fun_1 (): 11 print ("in the fun_1...") 12 13 14 fun_1 ()

Decorator: Simulated login authentication

1 # simulate website login and access authentication 2 #3 name = 'abc' 4 password = '000000' 5 def certi (model): # decorator 6 def outr (fun ): # add a layer of nested 7 def login (* args, ** kwargs) to the modifier and parameters: # to be compatible with various function parameters, add * args, ** the kwargs parameter is not fixed. 8 if model = 'Password': 9 print ('this is password Authentication') 10 user_name = input ('username :'). strip () 11 paswd = input ('password :'). strip () 12 if user_name = name and paswd = password: 13 print ('authenticated ') 14 return fun (* args, ** kwargs) 15 else: 16 print ('user or Password error, exit ') 17 Exit () 18 elif model = 'lamp ': 19 print ('this is lamp Authentication') 20 return fun (* args, ** kwargs) 21 else: 22 print ('authentication error') 23 return login24 return outr25 26 27 def indxe (): 28 print ('Welcome to homepage ') 29 30 @ certi (model = 'Password ') 31 def user (): 32 print ('Welcome to the user page: ') 33 34 @ certi (model = 'lamp') 35 def bbs (name ): 36 print ('Welcome % s to log on to the Forum !! '% Name) 37 38 indxe () 39 user () 40 bbs (name = 'yjj ')