Python中关于装饰器与迭代器以及生成器的实例详解

下面小编就为大家带来一篇老生常谈Python之装饰器、迭代器和生成器。小编觉得挺不错的，现在就分享给大家，也给大家做个参考。一起跟随小编过来看看吧

import time
def foo():
 """打印"""
 time.sleep(2)
 print("Hello boy!")
foo() 

import time
def timmer(func):
 def wrapper():
  """计时功能"""
  time_start=time.time()
  func()
  time_end=time.time()
  print("Run time is %f "%(time_end-time_start))
 return wrapper
def foo():
 """打印"""
 time.sleep(2)
 print("Hello boy!")
foo=timmer(foo)
foo()
#运行结果
Hello boy!
Run time is 2.000446 

import time
def timmer(func):
 def wrapper():
  """计时功能"""
  time_start=time.time()
  func()
  time_end=time.time()
  print("Run time is %f "%(time_end-time_start))
 return wrapper
@timmer  #等于 foo=timmer(foo)
def foo():
 """打印"""
 time.sleep(2)
 print("Hello boy!")
foo() 

<function timmer.<locals>.wrapper at 0x00000180E0A8A950> #打印foo的结果
<function timmer.<locals>.wrapper at 0x000001F10AD8A950> #打印wrapper的结果
foo() 

time_start=time.time()
 time.sleep(2)
 print("Hello boy!") 

Hello boy!
Run time is 2.000161 

import time
def timmer(func):
 def wrapper(*args,**kwargs):
  """计时功能"""
  start_time=time.time()
  res=func(*args,**kwargs)
  end_time=time.time()
  print("Run time is %f"%(end_time-start_time))
  return res
 return wrapper
@timmer 
def my_max(x,y):
 """返回两个值的最大值"""
 res=x if x > y else y
 time.sleep(2)
 return res
res=my_max(1,2)
print(res)
#运行结果
Run time is 2.000175 

def auth(filetype):
 def auth2(func):
  def wrapper(*args,**kwargs):
   if filetype == "file":
    username=input("Please input your username:")
    passwd=input("Please input your password：")
    if passwd == '123456' and username == 'Frank':
     print("Login successful")
     func()
    else:
     print("login error!")
   if filetype == 'SQL':
    print("No SQL")
  return wrapper
 return auth2
@auth(filetype='file') #先先返回一个auth2 ==》@auth2 ==》 index=auth2(index) ==》 index=wrapper
def index():
 print("Welcome to China")
index() 

def auth(filetype):
 def auth2(func):
  def wrapper(*args,**kwargs):
  return wrapper
 return auth2 

def wrapper(*args,**kwargs):
return wrapper 

if filetype == "file":
    username=input("Please input your username:")
    passwd=input("Please input your password：")
    if passwd == '123456' and username == 'Frank':
     print("Login successful")
     func() 

Please input your username:Frank
Please input your password：123456
Login successful
Welcome to China 

import time
#
def timmer(func):
 def wrapper():
  """计时功能"""
  time_start=time.time()
  func()
  time_end=time.time()
  print("Run time is %f "%(time_end-time_start))
  # print("---",wrapper)
 return wrapper
def auth(filetype):
 def auth2(func):
  def wrapper(*args,**kwargs):
   if filetype == "file":
    username=input("Please input your username:")
    passwd=input("Please input your password：")
    if passwd == '123456' and username == 'Frank':
     print("Login successful")
     func()
    else:
     print("login error!")
   if filetype == 'SQL':
    print("No SQL")
  return wrapper
 return auth2
@timmer
@auth(filetype='file') #先先返回一个auth2 ==》@auth2 ==》 index=auth2() ==》 index=wrapper
def index():
 print("Welcome to China")
index()

#测试结果
Please input your username:Frank
Please input your password：123456
Login successful
Welcome to China
Run time is 7.966267 

import time
def timmer(func):
 def wrapper():
  """计算程序运行时间"""
  start_time=time.time()
  func()
  end_time=time.time()
  print("Run time is %s:"%(end_time-start_time))
 return wrapper
@timmer
def my_index():
 """打印欢迎"""
 time.sleep(1)
 print("Welcome to China!")
my_index()
print(my_index.__doc__)

#运行结果
Welcome to China!
Run time is 1.0005640983581543:
计算程序运行时间 

import time
from functools import wraps
def timmer(func):
 @wraps(func)
 def wrapper():
  """计算程序运行时间"""
  start_time=time.time()
  func()
  end_time=time.time()
  print("Run time is %s:"%(end_time-start_time))
 return wrapper
@timmer
def my_index():
 """打印欢迎"""
 time.sleep(1)
 print("Welcome to China!")
my_index()
print(my_index.__doc__)
#运行结果
Welcome to China!
Run time is 1.0003223419189453:
打印欢迎 

my_list=[1,2,3]
li=iter(my_list)  #li=my_list.__iter__()
print(li)
print(next(li))
print(next(li))
print(next(li))
#运行结果
<list_iterator object at 0x000002591652C470>
2 

my_list=[1,2,3]
li=iter(my_list)
while True:
 try:
  print(next(li))
 except StopIteration:
  print("Over")
  break
 else:
  print("get!")
#运行结果
get!
get!
get!
Over 

from collections import Iterable
s="hello" #定义字符串
l=[1,2,3,4] #定义列表
t=(1,2,3) #定义元组
d={'a':1} #定义字典
set1={1,2,3,4} #定义集合
f=open("a.txt") #定义文本
# 查看是否都是可迭代的
print(isinstance(s,Iterable))
print(isinstance(l,Iterable))
print(isinstance(t,Iterable))
print(isinstance(d,Iterable))
print(isinstance(set1,Iterable))
print(isinstance(f,Iterable))
#运行结果
True
True
True
True
True
True 

from collections import Iterable,Iterator
s="hello"
l=[1,2,3,4]
t=(1,2,3)
d={'a':1}
set1={1,2,3,4}
f=open("a.txt")
# 查看是否都是可迭代的
print(isinstance(s,Iterator))
print(isinstance(l,Iterator))
print(isinstance(t,Iterator))
print(isinstance(d,Iterator))
print(isinstance(set1,Iterator))
print(isinstance(f,Iterator))
#运行结果
False
False
False
False
False
True 

def my_yield():
 print('first')
 yield 1
g=my_yield()
print(g)
#运行结果
<generator object my_yield at 0x0000024366D7E258> 

from collections import Iterator
def my_yield():
 print('first')
 yield 1
g=my_yield()
print(isinstance(g,Iterator))
#运行结果
True 

print(next(g))
#运行结果
first
1 

def my_yield():
 print('first')
 yield 1
 print('second')
 yield 2
 print('Third')
 yield 3
g=my_yield()
next(g)
next(g)
next(g)
#运行结果
first
second
Third 

def my_yield():
g=my_yield() 

 print('first')
 yield 1 

 print('second')
 yield 2
 print('Third')
 yield 3 

def foo():
 i=0
 while True:
  yield i
  i+=1
g=foo()
for num in g:
 if num < 10:
  print(num)
 else:
  break
#运行结果 

def eater(name):
 print('%s start to eat food'%name)
 while True:
  food=yield
  print('%s get %s ,to start eat'%(name,food))
 print('done')
e=eater('Frank')
next(e)
e.send('egg') #给yield送一个值，并继续执行代码
e.send('tomato')
#运行结果
Frank start to eat food
Frank get egg ,to start eat
Frank get tomato ,to start eat 

def init(func):
 def wrapper(*args):
  res = func(*args)
  next(res)  # 在这里执行next
  return res
 return wrapper
@init
def eater(name):
 print('%s start to eat food'%name)
 while True:
  food=yield
  print('%s get %s ,to start eat'%(name,food))
 print('done')
e=eater('Frank')
e.send('egg') 
e.send('tomato') 

所以在程序中有更多的生成器需要初始化的时候，直接调用这个装饰器就可以了。

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