Note python 12-day12

Advanced decorator

1, using a decorator function, but also through __name __, __ doc__ view to the calling function function name and comments

from functools Import Wraps
 DEF wrapper (FUNC):   # FUNC = Holiday 
    @wraps (FUNC)
     DEF Inner (* args, ** kwargs):
         Print ( ' before being decorated function performs do ' ) 
        RET = FUNC (* args, ** kwargs)
         Print ( ' after being decorated function performs do ' )
         return RET
     return Inner 

@wrapper    # Holiday = wrapper (Holiday) 
DEF Holiday (Day):
     '' ' this is a holiday notice ' ' ' 
    Print (' All the holiday% s days ' % Day)
     return  ' good fun ' 

Print (Holiday. __Name__ ) # print out the calling function function name 
Print (Holiday. __Doc__ ) # print out the annotation function is called function 

# result: 
    # Holiday 
    # this is a holiday notice

# From functools Import Wraps 
DEF wrapper (FUNC):   # FUNC = Holiday 
    # @wraps (FUNC) 
    DEF Inner (* args, ** kwargs):
         Print ( ' before the function is executed decorative doing ' ) 
        RET = FUNC (* args, ** kwargs)
         Print ( ' after the function execution garnished do ' )
         return RET
     return Inner 

@wrapper    # Holiday = wrapper (Holiday) 
DEF Holiday (Day):
     '' ' this is a holiday notice '' ' 
    Print ( 'All-day holiday% s ' % Day)
     return  ' good fun ' 

Print (Holiday. __Name__ ) # print out the name of the function calls the function 
Print (Holiday. __Doc__ ) # print out the comments function call function 

# the first row and three lines of code removed, the result 
# Inner 
# None

2, with parameters decorator

If you need to use a decorator function for some time, but after this time it does not have the time, you can use parameterized decorator

import time
FLAGE = False
def timmer_out(flag):
    def timmer(func):
        def inner(*args,**kwargs):
            if flag:
                start = time.time()
                ret = func(*args,**kwargs)
                end = time.time()
                print(end-start)
                return ret
            else:
                ret = func(*args, **kwargs)
                return ret
        return inner
    return timmer
# timmer = timmer_out(FLAGE)
@timmer_out(FLAGE)    #wahaha = timmer(wahaha)
def wahaha():
    time.sleep(0.1)
    print('wahahahahahaha')

@timmer_out(FLAGE)
def erguotou():
    time.sleep(0.1)
    print('erguotoutoutou')

wahaha()
erguotou()

3, a plurality of decorative function decorator

def wrapper1(func):
    def inner1():
        print('wrapper1 ,before func')
        ret = func()
        print('wrapper1 ,after func')
        return ret
    return inner1

def wrapper2(func):
    def inner2():
        print('wrapper2 ,before func')
        ret = func()
        print('wrapper2 ,after func')
        return ret
    return inner2

def wrapper3(func):
    def inner3():
        print('wrapper3 ,before func')
        ret = func()
        print('wrapper3 ,after func')
        return ret
    return inner3

@wrapper3
@wrapper2
@wrapper1
def f():
    print('in f')
    return '哈哈哈'

print(f())