Day9: Decorator

# l = [1,2,3]
# l.__iter_() #iter(l)
# Decorator:it's a function and can add additional functions for other functions
# Two principles:
#. 1): can't modify the source code of the functions which been decotated.
# 2):can't modify the calling mode if the functions which been decorated
# calculate the functing time:

import time
def cal(l):
start_time = time.time()
ret = 0
for i in l:
ret += i
stop_time = time.time()
print('functioning time:%s' %(stop_time-start_time))
return ret
print(cal(range(100)))

# The basic knowledge of decorator
# decorator = high stage functions + functions nest + close the package

import time
def timmer(func):
def wrapper(*args,**kwargs):
start_time = time.time()
res = func(*args,**kwargs)
stop_time = time.time()
print('functioning time:%s' %(stop_time-start_time))
return res
return wrapper

@timetimer # cal = timmer(cal(l))
def cal(l):
res = 0
for i in l:
time.sleep(0.1)
res += i
return res
res = cal(range(20))
print(res)

# high stage functions:the argument is function or the return value is function

import time
def foo():
print('from foo')
def timmer(func):
start_time = time.time()
func()
stop_time = time.time()
print('the functioning time is %s' %(stop_time-start_time))
# timmer(foo) #wrong:changed the name of asking
foo = timmer(foo)
foo()

# just using the high stage function can't satisfy the decorator

# function nesting:
def father(name):
# print('from my father %s' %name)
def son():
# name = 'laochen'
print('my father is %s' %name)
def grandson():
print('my grandfather is %s' %name)
grandson()
son()
father('chen')

# close bag:package the parameters including function names and other arguments;find the parameter in current circle first,if did't find then find in the upper stages

# Add a return value:

import time
def timer(func): # timer(test)
def wrapper(*args,**kwargs):
start_time = time.time()
res = func(*args,**kwargs) # take the return value of test()
stop_time = time.time()
print('the functioning time is %s' %(stop_time-start_time))
return res
return wrapper
@timer # :test = timer(test)
def test(name,age,gender):
time.sleep(3)
print('the test finished,the name is %s age is %s gender is %s' %(name,age,gender))
return 'this is the return value'
res = test('alex',19,'male')
print(res)

# reverse the value:

f1 = 1
f2 = 2
f1,f2 = f2,f1
print(f1)
print(f2)

# Write a simple background:

user_list =[
{'name':'zxver','passwd':'123'}
{'name':'alex','passwd':'123'}
{'name':'chen','passwd':'123'}
]
# make a name list
current_dic = {'username':None,'login':False}
# not so many times confirming
def auth_func(func):
def wrapper(*args,**kwargs):
if current_dic['username'] and user_dic['login']:
res = func(*args,**kwargs)
return res
username = iuput('username:').strip()
passwd = input('password:').strip()
for user_dic in user_list:
if username == user_dic['username'] and passwd == user_dic['passwd']:
current_dic['username'] = username
current_dic['login'] = True
res = func(*args,**kwargs)
return res
else:
print('wrong username or password')
return wrapper
@auth_func
def index():
print('Welcome to Jingdong')
@auth_func
def home(name):
print('%s Welcome home' %name)
@auth_func
def shopping_car(name):
print('There are (%s,%s,%s) in %s car' %('cosmetics','fruits','bags',name))
index()
home('zxver')
shopping_car('zxver')