python初学者怎么接单（Python中的三大神器！装饰器、迭代器、生成器！你精通哪个？）python初学 / python装饰器与生成器...

装饰器

以下示例是一个无参装饰器，为原函数添加了统计运行时间的功能import time #定义装饰器 def timer(func): def wrapper(*args,**kwargs): start_time = time.time() res = func(*args,**kwargs) stop_time = time.time() print("run time is %s" %(sto p_time-start_time)) return res return wrapper #调用装饰器 @timer def index(): l = [] for i in range(10000000): l.append(i) #调用阶段 index()

以下是一个有参装饰器，实现简单的认证功能，#数字表示程序依次执行顺序def auth2(auth_type): #1 #3 def auth(func): #4 #6 def wrapper(*args,**kwargs): #7 #10 if auth_type == file: #11 name=input(username: ) password=input(password: ) if name == zhejiangF4 and password == 666: print(auth successfull) res=func(*args,**kwargs) return res else: print(auth error) elif auth_type == sql: #12 print(nothing！) #13 return wrapper #8 return auth #5 @auth2(auth_type=sql) #2 def index(): print(welcome to inex page) index() #9

迭代器私信菜鸟007获取相关教程！

from collections import Iterable,Iterator s=hello l=[1,2,3] t=(1,2,3) d={a:1} set1={1,2,3,4} f=open(a.txt)

s.__iter__() l.__iter__() t.__iter__() d.__iter__() set1.__iter__() f.__iter__() print(isinstance(s,Iterable)) print(isinstance(l,Iterable)) print(isinstance(t,Iterable)) print(isinstance(d,Iterable)) print(isinstance(set1,Iterable)) print(isinstance(f,Iterable)) print(isinstance(s,Iterator)) print(isinstance(l,Iterator)) print(isinstance(t,Iterator)) print(isinstance(d,Iterator)) print(isinstance(set1,Iterator)) print(isinstance(f,Iterator))

运行结果如下：

可以看出，字符串、列表、字典、集合、元组、文件都是可迭代的，但是只有文件是迭代器生成器

例1：from urllib.request import urlopen def get(url): while True: def index(): return urlopen(url).read() url = yield index() g = get(http://www.baidu.com) next(g) def run(): while True: url = input("请输入URL：") if http:// not in url: print(g.send(http://+url)) else: print(g.send(url)) run()

例2：def cat(filename): with open(filename,r) as f: while True: line = f.readline() if not line: break else: yield line def grep(string,lines): for line in lines: if string in line: yield line g1 = cat(a.txt) g2 = grep(mac,g1) if __name__ == __main__: m = input("请输入命令：").strip() if m == "cat a.txt |grep mac": for i in g2: print(i)

补充：协程如果在一个函数内部yield的使用方式是表达式形式的话，如x=yield，那么该函数成为协程函数直接看例子吧def hello(func): def wrapper(*args,**kwargs): res = func(*args,**kwargs) next(res) return res return wrapper @hello def eater(name): print(%s start to eat food %name) food_list=[] while True: food=yield food_list print(%s get %s ,to start eat %(name,food)) food_list.append(food) print(done) e=eater("somebody") print(e.send(巧克力)) print(e.send("香蕉"))