yield的表达式：

# def init(func):
# def wrapper(*args,**kwargs):
# g=func(*args,**kwargs)
# next(g)
# return g
# return wrapper
#
# @init #foo=init(foo)
# def foo():
# print(‘starting‘)
# while True:
# x=yield None#return 1
# print(‘value ： ‘,x)
#
#
#
#
# g=foo() #wrapper()
#
# g.send(2)

#send的效果：
# 1：先从为暂停位置的那个yield传一个值，然后yield会把值赋值x
# 2：与next的功能一样

# print(g)
#
# next(g)
# print(‘=‘*30)
# print(g.send(1))
# print(‘=‘*30)
# print(g.send(2))
# print(‘=‘*30)
# print(next(g))
# print(‘=‘*30)
# print(g.send(None)) #g.send(None)等同于next(g)

# g.send(None) # next(g)

# g.send(2)

def init(func):
def wrapper(*args,**kwargs):
g=func(*args,**kwargs)
next(g)
return g
return wrapper
@init
def eater(name):
print(‘%s ready to eat‘ %name)
food_list=[]
while True:
food=yield food_list#return None
food_list.append(food)
print(‘%s start to eat %s‘ %(name,food))

# e=eater(‘alex‘)
# print(e.send(‘狗屎‘))
# print(e.send(‘猫屎‘))
# print(e.send(‘alex屎‘))

# def make_shit(people,n):
# for i in range(n):
# people.send(‘shit%s‘ %i)
#
# e=eater(‘alex‘)
# make_shit(e,5)

#应用：grep -rl ‘root‘ /etc
import os
def init(func):
def wrapper(*args,**kwargs):
g=func(*args,**kwargs)
next(g)
return g
return wrapper
#阶段一：递归地找文件的绝对路径，把路径发给阶段二
@init
def search(target):
‘search file abspath‘
while True:
start_path=yield
g = os.walk(start_path)
for par_dir, _, files in g:
# print(par_dir,files)
for file in files:
file_path = r‘%s\%s‘ % (par_dir, file)
target.send(file_path)
#阶段二：收到文件路径，打开文件获取获取对象，把文件对象发给阶段三
@init
def opener(target):
‘get file obj: f=open(filepath)‘
while True:
file_path=yield
with open(file_path,encoding=‘utf-8‘) as f:
target.send((file_path,f))

#阶段三：收到文件对象，for循环读取文件的每一行内容，把每一行内容发给阶段四
@init
def cat(target):
‘read file‘
while True:
filepath,f=yield
for line in f:
res=target.send((filepath,line))
if res:
break

#阶段四：收到一行内容，判断root是否在这一行中，如果在，则把文件名发给阶段五
@init
def grep(target,pattern):
‘grep function‘
tag=False
while True:
filepath,line=yield tag #target.send((filepath,line))
tag=False
if pattern in line:
target.send(filepath)
tag=True
#阶段五：收到文件名，打印结果
@init
def printer():
‘print function‘
while True:
filename=yield
print(filename)

start_path1=r‘C:\Users\Administrator\PycharmProjects\python5期\a‘
start_path2=r‘C:\Users\Administrator\PycharmProjects\python5期\a\b‘
g=search(opener(cat(grep(printer(),‘root‘))))

print(g)
# g.send(start_path1)
g.send(start_path2)

#
# def init(func):
# def wrapper(*args,**kwargs):
# g=func(*args,**kwargs)
# next(g)
# return g
# return wrapper
# @init
# def func():
# tag=False
# while True:
# x=yield tag #g.send(‘b‘) #x=‘b‘
# tag=False
# if ‘root‘ in x:
# print(x)
# tag=True
# g=func()
#
# print(g.send(‘a‘))
# print(g.send(‘root123‘))
# print(g.send(‘b‘))
# print(g.send(‘c‘))
# print(g.send(‘d‘))
# print(g.send(‘e‘))

内置函数：

Day 22 (06/19)yield的表达式、 生成器