迭代器的应用

#追加的代码
with open(‘a.txt‘,‘a+‘,encoding=‘utf-8‘) as f:
    while True:
        dl = input(‘请输入你的内容(q退出)：‘)
        if dl.lower() ==‘q‘:
            break
        else:
            f.write(dl+‘\n‘)

文件是atxt

import time
########动态查看添加文件的内容 cat
def get(acth):
    with open(acth,‘a+‘,encoding=‘utf-8‘) as f:
        f.seek(0,2)
        while True:
            line = f.readline()
            if not line:
                time.sleep(.3)
                # print(‘-------->‘)
                continue
            else:
                yield line.strip()

g = get(‘a.txt‘)
# print(next(g))
for line in g:
    print(line)



########动态查看文件追加过滤出来的内容  grup
def get(acth):
    with open(acth,‘a+‘,encoding=‘utf-8‘) as f:
        f.seek(0,2)
        while True:
            line = f.readline()
            if not line:
                time.sleep(.3)
                # print(‘-------->‘)
                continue
            elif ‘apple‘ in line:
                yield line
g = get(‘a.txt‘)
# print(next(g))
# for line in g:
#     print(line)
while True:
    try:
        ne = next(g)
        print(ne.strip())
    except StopIteration:
        break



###########管道流.....
#定义阶段
def get(acth):
    with open(acth,‘a+‘,encoding=‘utf-8‘) as f:
        f.seek(0,2)
        while True:
            line = f.readline()
            if not line:
                time.sleep(.3)
                continue
            else:
                yield line.strip()
def grup(pattern,lines):
    for line in lines:
        if pattern in line:
            yield line

#调用阶段
g = get(‘a.txt‘)
g1 = grup(‘apple‘,g)

#next触发执行g1生成器函数
for i in g1:
    print(i)

from urllib.request import urlopen
def get():
    print(‘strat‘)
    while True:
        url = yield
        print(urlopen(‘%s‘%url).read())

g = get()
g.__next__()
g.send(‘http://www.baidu.com‘)
g.send(‘http://www.taobao.com‘)