Iterator [Python] class CountDown, __iter__(), __next__()

# Python 3 : Iterator

class CountDown:

def __init__(self, top: int):

self.current = top + 1

def __iter__(self) -> 'CountDown':

return self

def __next__(self) -> int:

self.current -= 1

if self.current < 0:

raise StopIteration

else:

return self.current

if __name__ == '__main__':

c1 = CountDown(3)

print(type(c1)) # <class '__main__.CountDown'>

for i in c1:

print(i) # 3 2 1 0

c2 = CountDown(3)

print(next(c2)) # 3

print(next(c2)) # 2

print(next(c2)) # 1

print(next(c2)) # 0

print(next(c2)) # StopIteration

""" Output

3

2

1

0

3

2

1

0

StopIteration

"""