python-迭代器生成斐波那契数列

class Fibonacci(object):
    def __init__(self, all_num):
        self.all_num = all_num
        self.current_num = 0
        self.a = 0
        self.b = 1

    def __iter__(self):
        return self

    def __next__(self):
        if self.current_num < self.all_num:  # 判断是否可以迭代
            ret = self.a
            self.a, self.b = self.b, self.a + self.b
            self.current_num += 1
            return ret
        else:
            raise StopIteration  # 迭代完成，抛出异常，退出迭代


fib = Fibonacci(10)
for num in fib:
    print(num)


# 迭代器的优点，占用极小的空间去迭代