python实现从生成器中取固定角标的元素

#!/usr/bin/env python3

# -*- coding: utf-8 -*-

class A:

    def __init__(self):

        def r():

            i = 1

            while True:

                if i % 2 == 1:

                    yield i

                i += 1

        self._range = r()

    def __getitem__(self, given):

        l = []

        start = given.start

        stop = given.stop

        step = given.step

        if start is None:

            start = 0

        if step is None:

            step = 1

        i = 0

        while i < stop:

            r = next(self._range)

            if i>= start and i % step== 0:

                l.append(r)

            i+= 1

        return l

print(A()[2:6:2])