Python3学习笔记

def myYield_1():

   a, i ='yield',0

   whileTrue:

       print('before #%d'% i,end=", ")

       yield a, i

       print('after #%d'% i,end=", ")

       i +=1

def myYield_2():

   a, i ='yield_a',0

   b, i ='yield_b',0

   whileTrue:

       print('before #%d'% i,end=", ")

       yield a, i

       yield b, i

       print('after #%d'% i,end=", ")

       i +=1

it1 = iter(myYield_1())

it2 = iter(myYield_2())

for i in range(10):

   print("next #%d"% i,end=": ")

   print(next(it1))

print('\n')

for i in range(10):

   print("next #%d"% i,end=": ")

   print(next(it2))

输出是这样的：

next#0: before #0, ('yield', 0)

next#1: after #0, before #1, ('yield', 1)

next#2: after #1, before #2, ('yield', 2)

next#3: after #2, before #3, ('yield', 3)

next#4: after #3, before #4, ('yield', 4)

next#5: after #4, before #5, ('yield', 5)

next#6: after #5, before #6, ('yield', 6)

next#7: after #6, before #7, ('yield', 7)

next#8: after #7, before #8, ('yield', 8)

next#9: after #8, before #9, ('yield', 9)

next#0: before #0, ('yield_a', 0)

next#1: ('yield_b', 0)

next#2: after #0, before #1, ('yield_a', 1)

next#3: ('yield_b', 1)

next#4: after #1, before #2, ('yield_a', 2)

next#5: ('yield_b', 2)

next#6: after #2, before #3, ('yield_a', 3)

next#7: ('yield_b', 3)

next#8: after #3, before #4, ('yield_a', 4)

next#9: ('yield_b', 4)