摘要
一. 上节课复习
二. 协程函数初始化装饰器
三. send实现爬网页
四. 面向过程的程序设计
五. 列表生成式
六. 三元表达式
七.生成器表达式
八. 声明式编程
作业
今日总结

def func():n=0while True:yield nn += 1
g=func()
res=next(g)
for i in g:pass

def eater(name):print('%s start to eat '%name)while True：food=yieldprint('%s eat %s'%(name,food))
e=eater('zhejiangF4')

def foo(func):def foo1(*args,**kwargs):res = func(*args,**kwargs)next(res)return res        #此处理解 生成器是一次性的return foo1@foo        #eater = foo(eater) = foo1
def eater(name):print('%s start to eat food '% name)food_list = []while True:food = yield food_listprint('%s get %s, to start eat '% (name, food))food_list.append(food)print('Done')e = eater('钢蛋')        #foo1('钢蛋')
print(e.send('123'))

from urllib.request import urlopendef my_next(func):def foo(*args,**kwargs):res = func(*args,**kwargs)next(res)return resreturn foo@my_next
def get():while True:url = yieldres = urlopen(url).read()        #爬网页返回值print(res)        #输出爬网页结果g=get()
g.send('http://www.baidu.com')
g.send('http://www.python.org')

# grep -rl 'python' C:\egon
import os#装饰器，将生成器next初始化
def init(func):def foo(*args,**kwargs):res = func(*args,**kwargs)next(res)return resreturn foo@init
def search(target):'查找文件绝对路径'while True:dir_path = yield        #此yield放在while外还是内有疑问:yield放在while外就会造成死循环，无法进行下次yieldg = os.walk(dir_path)        #g为迭代器for i in g:# print(i)for j in i[-1]:file_path = '%s\\%s'%(i[0],j)target.send(file_path)@init
def opener(target):'打开文件获取文件句柄'while True:file_path = yieldwith open(file_path) as f:target.send((f,file_path))        #send传递两个文件时，需加括号@init
def cat(target):'读取文件内容'while True:f,file_path = yieldfor line in f:        #读取一行文件target.send((line,file_path))@init
def grep(target,pattern):    #传递两个参数，其中pattern为要过滤的字符串'过滤文件一行中是否有python'while True:line,file_path = yieldif pattern in line:target.send(file_path)        #需传递文件路径@init
def printer():'打印文件路径'while True:file_path = yieldprint(file_path)g=search(opener(cat(grep(printer(),'python'))))
g.send('C:\\egon')

egg_list = []for i in range(100):egg_list.append('egg%s'% i)
print(egg_list)

egg_list = ['egg%s'%i for i in range(100)]
print(egg_list)

#列表内只会添加大于50的数字
egg_list = ['egg%s'%i for i in range(100) if i >50]
print(egg_list)

[expression for item1 in interable if condition1for item2 in interable if condition2…for itemN in interable if conditionN]

res = []
for item1 in interable:if condition1:for item2 in interable:if condition2:…for itemN in interable:if conditionN:res.append(expression )

import osg = os.walk('C:\\egon')
l = ['%s\\%s'% (i[0],j) for i in g for j in i[-1]]
print(l)
#['C:\\egon\\a.txt - 副本.txt', 'C:\\egon\\a.txt.txt', 'C:\\egon\\a\\a.txt.txt', 'C:\\egon\\a\\a2.txt.txt', 'C:\\egon\\b\\a.txt.txt', 'C:\\egon\\b\\a1.txt.txt']

name = 'alex'
name = 'egon'res = 'sb' if name =='alex' else 'shuai'
print(res)        #输出shuai

(expression for item1 in interable if condition1for item2 in interable if condition2…for itemN in interable if conditionN)

#读取文件，并去掉每一行两头空格
f = open('a.txt')
g= (line.strip() for line in f)
print(next(g))

#鸡蛋  5  3
#特斯拉 10000000.2  5
#上衣  1000    3
#裤子  2000    3
#袜子  100
#读取包含以上信息的文件，并计算总共花费#第一种传统写法
total = []
with open('b.txt','r',encoding='utf-8') as f:for line in f:goods=line.split()    #split用法及返回值需加强# print(goods)res = float(goods[1])*float(goods[-1])total.append(res)
print(total)
print(sum(total))#第二种声明式编程写法
f=open('b.txt','r',encoding='utf-8')    #不能用with 否则会IO操作报错
total=(float(line.split()[1])*float(line.split()[-1]) for line in f)print(total)
print(sum(total))

#[{'name': '袜子', 'price': '100', 'num': '3'}, {'name': '袜子', 'price': '100', 'num': '3'}, {'name': '袜子', 'price': '100', 'num': '3'}, {'name': '袜子', 'price': '100', 'num': '3'}, {'name': '袜子', 'price': '100', 'num': '3'}]
# 基本写法
res = []
d = {}with open('b.txt','r',encoding='utf-8') as f:for line in f:l = line.split()d['name'] = l[0]d['price'] = l[1]d['num'] = l[2]res.append(d)
print(res)

with open('b.txt','r',encoding='utf-8') as f:res = (line.split() for line in f)dic_g = ({'name':line[0],'price':line[1],'num':line[2]} for line in res)goods_dic = next(dic_g)print(goods_dic['num'])

with open('b.txt') as f:d = f
print(d)        #有内存地址，不是很理解
print(next(d))    #报错