coroutine function

# yield turns the function into an iterator 
# The return value of return is only returned once, yield returns multiple times 
# The state of the function when it pauses and continues to run the next time is saved by yield 
# Coroutine function 

# 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('Steel Egg') 
# # print(e) 
# 
# next(e) 
# e.send("bun") 
# e.send("rice") 

# print(next(e)) 

# use List 
# 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('Steel Egg') 
# print(next(e)) 
# print(e. send("bun")) 
# print(e .send("rice")) 

# Lesson iterative: Objects with __iter__ methods under the object are all iterable objects 
# Iterator: The result obtained by object .__iter__() is iterator 
# Features of iterator: 
# Iteration __next__() takes the next value 
# Advantages: 
# 1. Provides a unified way to iterate objects without relying on index 
# 2. Lazy calculation 

# Disadvantages: 
# 1. Unable to get the length of the iterator 
# 2, One-time, you can only take the value backward, not forward, you can't take the value of a certain position like an index 

# Generator: If the function contains yield, then the execution result of this function is the generator 
# The essence of the generator is Iterator 
# def func(): 
# n=0 
# while n<5: 
# yield n 
# n+=1 
# g=func() 
# print(next(g)) 
# print(next(g)) 
#
# for i in g: 
# print(i) 

# Summarize the function of yield: 
# 1. It is equivalent to encapsulating the __iter__ and __next__ methods inside the function 
# 2. Compared with return, return can only be returned once, while yield Can return multiple times # 3. The state where the function has been suspended and continued to run is the expression form 
of # yield saved by yield: # food=yield # def eater(name): # print('%s start to eat' %name) # food_list=[] # while True: # food=yield food_list # print('%s eat %s' %(name,food)) # food_list.append(food) # # def aa # e=eater('zhejiangF4' ) # print(next(e)) # e.send("stool") # The difference between e.send and next(e) # 1. If the yield in the function is in the form of an expression, then it must first be next(e) # 2 , The common feature of the two allows the function to continue running at the position where it was last paused. The difference is that send will pass a value to yield when triggering the next code execution.























# I want to pass parameters without adding next 
# def init(func): 
# def wrapper(*args,**kwargs): 
# res=func(*args,**kwargs) 
# next(res) 
# return res # Return to next(res), which is the next step of execution (return food_list) 
# return wrapper 
# 
# @init #eater=init(eater) 
# def eater(name): 
# print('%s start to eat' %name) 
# food_list=[] 
# while True: 
# food=yield food_list # From return res food=yield food_list means return food_list (execute only once) +food=yield 
# print('%s eat %s' %(name ,food)) 
# food_list.append(food) 
# 
# 
# e=eater('zhejiangF4') #wrapper('zhejiangF4') 
# # print(next(e)) 
# e.send("stool")
# e.send("pee") 

# Crawl web pages and open different URLs constantly 
# from urllib.request import urlopen 
# def get(): 
# while True: 
# url=yield 
# res=urlopen(url).read( ) 
# print(res) 
# 
# g=get() 
# next(g) # Make cursor stop at url=yield 
# g.send('http://www/python.org') # To pass value to URL 

# Coroutine function 
# 

# Print out the path to the root file in the etc directory, # Enter # grep -rl 'root' /etc # 
in the virtual machine to get the result, but with PYTHON, you need the following method # first Writing process: # def search(): # 'Find the absolute path of the file' # pass # # def opener(): # 'Open the file and get the file handle' # pass # # def cat(): # 'Read the file content '#     pass















# 
# def grep(): 
# 'Filter a line for python' 
# pass 
# 
# def printer(): 
# 'Print the path containing python' 
# pass 
# 
# When the computer is running, enter import os 
# os.walk( 'c:\\egon'') 
# or 
# os.walk(r'c:\egon'') # r means that all characters on the right are normal characters, no translation characters 
# g=os.walk(r'c:\ egon'') 
# next(g) 
# next(g) 
# We find the absolute path of the file by concatenating the first value with the third value 

# import os 
# 
# def search(): 
# while True: 
# dir_name= yield 
# g=os.walk(dir_name) 
# for i in g: 
# # print(i) 
# for j in i[-1]: 
# file_path='%s\\%s' %(i[0], j)
#                 print(file_path)
#
# e=search()
# next(e)
# e.send('c:\\egon')

# 我想把print(file_path)的结果存起来
import os

def init(func):
    def wrapper(*args,**kwargs):
        res=func(*args,**kwargs)
        next(res)
        return res
    return wrapper

@init
def search(target):
    while True:
        dir_name=yield
        g=os.walk(dir_name)
        for i in g:
            # print(i)
            for j in i[-1]:
                file_path='%s\\%s' %(i[0],j)
                target.send(file_path) # 把file_path值传到target中

@init
def opener(target):
    'Open the file, get the file content' 
    while True: 
        file_path=yield 
        with open(file_path) as f: 
            target.send(f) 

@init 
def cat(): 
    while True: 
        f=yield 
        for line in f: