试写Python内建函数range()

还没查阅源码，先试着练手

class my_range(object):

    def __init__(self, *args):
        if not args:
            raise TypeError, 'range expected at least 1 arguments, got 0'
        elif len(args) == 1:
            self.start, self.stop, self.step = (0, args[0], 1)
        elif len(args) == 2:
            self.start, self.stop, self.step = (args[0], args[1], 1)
        elif len(args) == 3:
            self.start, self.stop, self.step = args
        else:
            raise TypeError, 'range expected at most 3 arguments, got %d' % len(args)
        self.n = 0

    def next(self):
        while True:
            r = self.start + self.step * self.n
            if r >= self.stop:
                break
            self.n += 1
            return r
        raise StopIteration

    def __iter__(self):
        return self