Python basis decorator

Decorator (decorator)

1. Function basis

   # Function.py function 
   # 1) is the object function 
   DEF Hello ():
        return  ' ! The Hello, World ' 
   
   FUNC = Hello
    Print (FUNC)   # <Object> 
   Print (FUNC ()) 
   
   
   # 2) can be nested functions, defined in another function of the internal 
   DEF Show ():
        Print ( ' the Run in Show () ' )
        DEF Message (= Word ' the Hello ' ):
            return Word
        Print (Message ()) 
   
   Show () 
   
   
   # . 3) function returns as an argument 
   DEF getWordType ( kind =''):
       def default(word=''):
           return word
       def upper(word=''):
           return word.upper()
       def lower(word=''):
           return word.lower()
   
       if kind.lower() == 'lower':
           return lower
       elif kind.lower() == 'upper':
           return upper
       else:
           return default
   
   wordType = getWordType('upper')
   print(wordType)
   print(wordType('Resistance is futile!'))
   
   
   # 4）函数作为参数传入
   def getName(name='leo'):
       return name
   
   def foo(func):
       print('I will call the getName function later')
       print(func())
   
   foo(getName)

    

2. Decorator and a function to compare

   # decorator.py  装饰器
   # 不使用装饰器情况
   def my_new_decorator(a_function_to_decorator):
       def the_wrapper_around_the_original_function():
           print('Befor the function runs')
           a_function_to_decorator()
           print('After the function runs')
       return the_wrapper_around_the_original_function  # 将函数作为参数返回
   
   
   def a_stand_alone_function():
       print("I'm a stand alone function, don't you dare modify me.")
   
   
   a_stand_alone_function()
   a_stand_alone_function_decorated = my_new_decorator(a_stand_alone_function)  # 将函数作为参数传入
   print(a_stand_alone_function_decorated)
   a_stand_alone_function_decorated()
   
   # 使用装饰器 语法糖"@"
   @my_new_decorator
   def another_stand_alone_function():
       print('leave me alone')
   
   
   another_stand_alone_function()
   # same as: another_stand_alone_function = my_new_decorator(another_stand_alone_function)

    

3. Decorative applications

   # decorator_web.py  web中的装饰器应用
   def makebold(func):
       def wrapper():
           return '<b>' + func() + '</b>'
       return wrapper
   
   def makeitalic(func):
       def wrapper():
           return '<i>' + func() + '</i>'
       return wrapper
   
   @makebold
   @makeitalic
   def word():
       return 'Hello, decorator!'
   
   
   print(word())

   # Decorator_time.py decorator check function of operating time 
   Import Time
    Import OS 
   
   
   DEF Timer (FUNC):
        DEF warpper (CWD): 
           time_begin = time.ctime ()
            Print ( ' the Begin @ ' + time_begin) 
           FUNC (CWD) 
           TIME_END = time.ctime ()
            Print ( ' End @ ' + TIME_END) 
   
           Print ( ' the Begin @ ' + time_begin)
            Print ( ' End @ '+ TIME_END)
        return warpper 
   
   
   @timer 
   DEF Walk (R & lt CWD = ' D: \ PyCharm \ Python \ Practice ' ):
        for the root, dirs, Files in os.walk (CWD):
            # Print (the root) directory of Print # all subdirectories absolute path 
           # Print (dirs) # print the list of subdirectories in each directory 
           # Print (files) # print a list of all files under 
           Print (root)
            for file in files:
                Print ( ' \ t ' + file ) 
   
   
   Walk (CWD = R & lt ' D: \ PyCharm ' )

    

4. It contains all the parameters and the return value of the decorator

   # decorator_args.py  包含所有参数的装饰器
   import time
   def timer(func):
       def inner(*args, **kwargs):
           start = time.time()
           re = func(*args, **kwargs)
           end = time.time()
           return re
       return inner
   
   
   @timer  #==> func1 = timer(func1)
   def func1(a, b):
       print('in func1')
       return a, b
   
   
   @timer #==> func2 = timer(func2)
   def func2(a):
       print('In func2 and get', a)
       return 'func2 over'
   
   
   func1('aaaaaa', 'bbbbbb')
   print(func2('aaaaaa'))

    

5. That the function is a normal function can be used decorated method

   # decorator_method.py
   from functools import wraps
   
   def deco(func):
       @wraps(func)
       def wrapper(*args, **kwargs):
           return func(*args, **kwargs)
       return wrapper
   
   @deco
   def index():
       '''docs here in decorator'''
       print('from index')
   
   
   index()
   print(index.__name__)
   print(index.__doc__)