32 lines
771 B
Python
32 lines
771 B
Python
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if __name__ == "__main__":
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a = [1, 2, 3, 4]
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# python自带的reversed函数搞定了反向迭代，其本质时调用了__reversed__方法
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for i in reversed(a):
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print(i)
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for i in a.__reversed__():
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print(i)
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# 如果想要实现类的反向迭代，可以在实现__iter__()方法的同时搞一个__reversed__()方法
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class Countdown:
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def __init__(self, start):
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self.start = start
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def __iter__(self):
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n = self.start
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while n > 1:
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yield n
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n -= 1
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def __reversed__(self):
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n = 1
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while n <= self.start:
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yield n
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n += 1
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a = Countdown(10)
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for i in reversed(a):
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print(i)
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