39 lines
1.4 KiB
Python
39 lines
1.4 KiB
Python
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from collections import deque
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if __name__ == "__main__":
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# 在学到了生成器函数以后，有一个巨大陷阱那就是尝试用生成器函数解决一切问题
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# 当生成器函数需要与外界交互的时候，就会让它非常复杂
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# 所以生成器我们就让它安心生成，在需要记录或者与外界交互的时候，写一个生成器类
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class FbbIterClass:
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def __init__(self,nums, history_len=3):
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self.nums = nums
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self.history = deque(maxlen=history_len)
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def __iter__(self):
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a0, a1 = 1, 1
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index = 0
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while index < self.nums:
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self.history.append(a0)
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yield a0
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a0, a1 = a1, a0 + a1
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index += 1
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fbbs = FbbIterClass(5)
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# 先用生成器生成，结果在生成的过程中会存入历史队列
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for i in fbbs:
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print(i)
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# 当然，在使用for之外的方法进行迭代时，需要额外套一层iter来转发请求到__iter__()
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fbb_iter = iter(fbbs)
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print(fbb_iter.__next__())
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print(fbb_iter.__next__())
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print(fbb_iter.__next__())
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print(fbb_iter.__next__())
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print(fbb_iter.__next__())
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# 这种方法的好处是，可以在迭代时随时暴露一些东西给外部程序，比如属性和状态
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for line in fbbs.history:
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print("history{}".format(line))
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