---- decorator

1. The role of decorator

　　In no way alter the function call based on before and after the function to add functionality .

2. syntactic sugar

　Position is placed above the decorative function

DEF Timer (F):　　　# decorator function
     DEF Inner (): 
        Start = the time.time () 
        F ()        # decorated function 
        End = the time.time ()
         Print (End - Start)
     return Inner 

@timer    # syntactic sugar : @ decorator function name 
DEF FUNC (): 
    the time.sleep ( 0.1 )
     Print ( ' 111 ' ) 

# action syntactic sugar corresponds executed here: func = timer (func), i.e. the inner assign FUNC 
Fun ( )

3. The decorated function return value

DEF Timer (F):
     DEF Inner (): 
        Start = the time.time () 
        RET = F ()       # decorated function 
        End = the time.time ()
         Print (End - Start)
         return RET
     return Inner 

@timer    # syntactic sugar : @ decorator function name 
DEF FUNC (): 
    the time.sleep ( 0.1 )
     Print ( ' 111 ' )
     return '222 '　　# add a return value

 # syntactic sugar acts as performed here: FUNC = Timer (FUNC) 

RET =Fun ()
 print (right)

Function with parameters to be decorated 4

In the position of all parameters need to add parameters to join

DEF Timer (F):
     DEF Inner (* args, ** kwargs):　　# universal parameter 
        Start = the time.time () 
        RET = F (* args, ** kwargs)       # decorated function 
        End = the time.time ( )
         Print (End - Start)
         return RET
     return Inner 

@timer    # syntactic sugar: @ decorator function name 
DEF FUNC (A, B): 
    the time.sleep ( 0.1 )
     Print ( ' 111 ' , A)
     return '222'　　# Add The return value 

#Syntactic sugar equivalent action executed here: FUNC = Timer (FUNC) 

RET = Fun (. 1, B = 2 )
 Print (RET)