【笔记】反向迭代

实现一个连续浮点数发生器FloatRange，产生一些连续浮点数。

实现反向迭代协议的__reversed__方法，它返回一个迭代器。

class FloatRange:
    def __init__(self,start,end,step = 0.1):
        self.start = start
        self.end = end
        self.step = step
    
    def __iter__(self):
        t = self.start
        while t <= self.end:
            yield t
            t += self.step
    
    def __reversed__(self):
        t = self.end
        while t >= self.start:
            yield t
            t -= self.step
            
if __name__ == "__main__":
    
    for x in FloatRange(1.0,4.0,0.5):
        print x
    
    for x in reversed(FloatRange(1.0,4.0,0.5)):
        print x