Decorator(1) 7/2/18

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Decorator function:


 1) add functionality 

2) modify behavior 

3) perform setup/teardown 

4) diagnostic(timing)

----------------------------------------------
Original view : 


def shout(wrapped):
    def inner(*args, **kargs):
        print('Before')
        ret = wrapped(*args,**kargs)
        print('After')
        return ret
    return inner
def myfunc():
    print('Shoot him')
    
myshout = shout(myfunc)
myshout()

output :



Before



Shoot him



After


----------------------------------------------
def shout(wrapped):
    def inner(*args, **kargs):
        print('Before')
        ret = wrapped(*args,**kargs)
        print('After')
        return ret
    return inner
@shout


def myfunc():
    print('Shoot him')

myfunc()
#++ output :# Before# Shoot him# After###################### but !! #  Still it has a problem
#  You can't get the right name !!myfunc.__name__  # Out[135]: 'inner'

---------------------------------------------
remedy for this !!
---------------------------------------------
from functools import wraps
def shout(wrapped):
    @wraps(wrapped)
    def inner(*args, **kargs):
        print('Before')
        ret = wrapped(*args,**kargs)
        print('After')
        return ret
    return inner
@shout
def myfunc():
    print('Shoot him')

myfunc()


output :
Before
Shoot him
After


#No more problem now !


myfunc.__name__  # Out[135]: 'myfunc'








---------------------------------------------


Usage (1) : counting !!


---------------------------------------------

def count(wrapped):
    def inner(*args, **kwargs):
        inner.counter += 1        return wrapped(*args, **kwargs)
    inner.counter = 0    return inner


@count


def myfunc():
    print('counting: ')

myfunc()
myfunc()
myfunc()
myfunc()
myfunc()
myfunc.counter    # 5


---------------------------------------------


Usage (2) : timing 


---------------------------------------------

import time
def timer(wrapped):
    def inner(*args, **kwargs):
        t = time.time()
        for i in range(10000):
            ret = wrapped(*args, **kwargs)
        print(time.time() -t)
    return inner

@timer


def myfunc():
    # print('so simple!')
myfunc()  # 0.2610
































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