如果您从未重新定义任何内置函数,为什么要导入内置函数？

Question

我正在查看这个repo https://github.com/datacenter/cobra中的代码,我看到几个文件中的内置导入如下:

cobra/internal/codec/jsoncodec.py:15:from builtins import str
cobra/internal/codec/xmlcodec.py:15:from builtins import str
cobra/internal/base/moimpl.py:16:from builtins import next
cobra/internal/base/moimpl.py:17:from builtins import str
cobra/internal/base/moimpl.py:18:from builtins import object
cobra/internal/rest/accessimpl.py:15:from builtins import object
cobra/internal/rest/accessimpl.py:16:from builtins import str
cobra/mit/session.py:15:from builtins import str
cobra/mit/session.py:16:from builtins import object
cobra/mit/meta.py:16:from builtins import str
cobra/mit/meta.py:17:from builtins import next
cobra/mit/meta.py:18:from builtins import object
cobra/mit/access.py:21:from builtins import object
cobra/mit/naming.py:15:from builtins import next
cobra/mit/naming.py:16:from builtins import str
cobra/mit/naming.py:17:from builtins import object
cobra/mit/request.py:15:from builtins import str
cobra/mit/request.py:16:from builtins import object

这样做的逻辑是什么？模块中没有位置可以重新定义这些对象.

在旁注中,这打破了我期望从文档中指定的此模块的2.7兼容性.

Answer 1

我不知道为什么它专门用于眼镜蛇,但它是编写在python 2和3中工作的代码的技巧.请参阅compatible_idioms.它不应该打破2.7,但你必须写"3x-ish"代码.

更新

对于2.x,builtins需要安装模块pypi.它不是本机内置函数,而是3.x兼容更新.