Python 迭代器对象需要支持两个方法.
iter(),返回迭代器对象自身. 用于for x in 中.
next(),放回迭代器的下一个值.如果没有下一个值可以返回,那么需要抛出StopIteration异常.
class Counter(object):
def __init__(self, low, high):
self.current = low
self.high = high
def __iter__(self):
return self
def __next__(self):
if self.current > self.high:
raise StopIteration
else:
self.current += 1
return self.current - 1
>>> c = Counter(5, 8)
>>> for i in c:
print(i, end=' ')
5 6 7 8
