Python异常链接

Python异常链接

异常链接仅在Python 3中可用，您可以在其中编写：

try:    v = {}['a']except KeyError as e:    raise ValueError('failed') from e

产生像

Traceback (most recent call last):  File "t.py", line 2, in <module>    v = {}['a']KeyError: 'a'The above exception was the direct cause of the following exception:Traceback (most recent call last):  File "t.py", line 4, in <module>    raise ValueError('failed') from evalueError: failed

在大多数情况下，您甚至都不需要

from

; 默认情况下，Python 3将显示异常处理期间发生的所有异常，如下所示：

Traceback (most recent call last):  File "t.py", line 2, in <module>    v = {}['a']KeyError: 'a'During handling of the above exception, another exception occurred:Traceback (most recent call last):  File "t.py", line 4, in <module>    raise ValueError('failed')ValueError: failed

您可以在 Python 2中执行的 *** 作 是向您的异常类添加自定义属性，例如：

class MyError(Exception):    def __init__(self, message, cause):        super(MyError, self).__init__(message + u', caused by ' + repr(cause))        self.cause = causetry:    v = {}['a']except KeyError as e:    raise MyError('failed', e)