python-- generator (Generator)

# Generator function 
# DEF Generator (): 
#      Print (. 1) 
#      return 'A' 
# 
# RET = Generator () 
# Print (RET) 

# function as long as the yield keyword is contained generator function 
# yield can not return common and need to write the function 
# DEF generator (): 
#      Print (. 1) 
#      the yield 'a' 
# # generator function: get a generator after the execution as a return value 
# RET = generator () 
# Print (RET) 
# Print (RET .__ Next __ ()) 

# DEF Generator (): 
#      Print (. 1) 
#      the yield 'A' 
#      Print (2)
#     yield 'b'
#     yield 'c'
# g = generator()
# for i in g:
#     print(i)
# ret = g.__next__()
# print(ret)
# ret = g.__next__()
# print(ret)
# ret = g.__next__()
# print(ret)

#娃哈哈%i
def wahaha():
    for i in range(2000000):
        yield '娃哈哈%s'%i
# g = wahaha()
# g1 = wahaha()
# print(g.__next__())
# print(g1.__next__())

# g = wahaha()
# count = 0
# for i in g:
#     count +=1
#     print(i)
#     if count > 50:
#         break
# # print('*******',g.__next__())
# for i in g:
#     count +=1
#     print(i)
#     if count > 100:
#         break

Monitor the input file

def tail(filename):
    f = open(filename,encoding='utf-8')
    while True:
        line = f.readline()
        if line.strip():
            yield line.strip()

g = tail('file')
for i in g:
    if 'python' in i:
        print('***',i)