python 装饰器的使用示例

无参修饰 ,无参数时不需要调用

def log1(func):
 func()
@log1
def test():
 print('test:')

有参修饰

def log2(func):
 def inner(*args, **kwargs):
   func(*args, **kwargs)
 return inner
@log2
def test(num):
 print('testlog2:',num,test.__name__)
test(20) #相当于log(test(20))

@wraps可以保证装饰器修饰的函数的name的值保持不变

不带参数的装饰器

def log3(func):
 @wraps(func)
 def inner(*args, **kwargs,):
   func(*args, **kwargs)
 return inner
@log3
def test(num):
 print('testlog3:',num,test.__name__)
test(30) #相当于log(test(30))

带参数的装饰器

def log4(level):
 def log(func):
   @wraps(func)
   def inner(*args, **kwargs,):
     if level == "warn":
       print("％s is running" ％ func.__name__)
     func(*args, **kwargs)
   return inner
 return log
@log4(level="warn")
def test(num):
 print('testlog4:', num, test.__name__)
test(40)

实现带参数和不带参数的装饰器自适应

def log(arg):
 if callable(arg): # 判断参入的参数是否是函数，不带参数的装饰器调用这个分支
   def log3(func):
     @wraps(func)
     def inner(*args, **kwargs, ):
       func(*args, **kwargs)
     return inner
   return log3
 else:
   def log4(func):
     @wraps(func)
     def inner(*args, **kwargs,):
       if arg == "warn":
         print("％s is running" ％ func.__name__)
       func(*args, **kwargs)
     return inner
   return log4
@log(arg=None)
def test(num):
 print('testlog:', num, test.__name__)
test(0)

返回入参出参

def log5(func):
 def inner(*args, **kwargs):
   print('入参：',func.__name__, args, kwargs)
   res =func(*args, **kwargs)
   print('出参：',func.__name__, res)
   return res
 return inner
@log5
def test(num):
 print('testlog5:', num, test.__name__)
 return num
print(test(50))

类装饰器

class Loging:
 def __init__(self,level):
   self.level = level

def __call__(self,func):
   @wraps(func)
   def inner(*args, **kwargs):
     if self.level == "warn":
       self.notify(func)
     func(*args, **kwargs)
   return inner

def notify(self,func):
   print ("％s is running" ％ func.__name__)

@Loging(level="warn")
def test(num):
 print('testLoging:', num, test.__name__)
test(0)

来源：https://www.cnblogs.com/shuzf/p/13434477.html