如何模仿Python 3的提升...从Python 2？ [英] How to imitate Python 3's raise ... from in Python 2?

问题描述

Python 3具有整洁的

Python 3 has the neat

try:
    raise OneException('sorry')
except OneException as e:
    # after a failed attempt of mitigation:
    raise AnotherException('I give up') from e

语法，允许提高后续异常而不会丢失上下文。在Python 2中我可以想出的最好的类比是

syntax which allows raising a followup exception without loosing context. The best analogy I could come up with in Python 2 is

raise AnotherException((e,'I give up')), None, sys.exc_info()[2]

其中（e， ''）是一个丑陋的黑客，将原始异常的名字包含在邮件中。但是没有更好的方法吗？

where the (e,'') is an ugly hack to have the original exception's name included in the message. But isn't there a better way?

推荐答案

有一个 raise_from .org / quickstart.htmlrel =nofollow> python-future ;只需安装它

pip install future

并导入使用

from future.utils import raise_from
# or: from six import raise_from

class FileDatabase:
    def __init__(self, filename):
        try:
            self.file = open(filename)
        except IOError as exc:
            raise_from(DatabaseError('failed to open'), exc)

更新

兼容性包六个也支持从版本1.9（ raise_from ，于2015年发布）。它的使用方式与上述相同。

UPDATE

The compatibility package six also supports raise_from, from version 1.9 (released in 2015). It is used in the same manner as above.

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