如何在 Python 中找到引发异常的位置

Question

如何确定在哪个函数中引发了异常。例如存在两个函数：'foo'和'bar'。在 'foo' 中会随机引发异常。

import random


def foo():
    if random.randint(1, 10) % 2:
        raise Exception
    bar()


def bar():
    raise Exception

try:
    foo()
except Exception as e:
    print "Exception raised in %s" % ???

Answer 1

import inspect

try:
    foo()
except Exception as e:
    print "Exception raised in %s" % inspect.trace()[-1][3]

Answer 2

我使用 traceback 模块，如下所示：

import traceback

try:
    1 / 0
except Exception:
    print traceback.format_exc()

这给出了以下输出：

Traceback (most recent call last):
  File "<ipython-input-3-6b05b5b621cb>", line 2, in <module>
    1 / 0
ZeroDivisionError: integer division or modulo by zero

如果代码从文件中运行，回溯将告诉错误发生的行和字符号:)

编辑：

容纳Habibutsu的评论：Yes, it's useful for printing, but when needed to get more info (for example function name) - not suitable

文档页面告诉您如何以编程方式提取跟踪：http://docs.python.org/2/library/traceback.html

从上面链接的页面：

>>> import traceback
>>> def another_function():
...     lumberstack()
...
>>> def lumberstack():
...     traceback.print_stack()
...     print repr(traceback.extract_stack())
...     print repr(traceback.format_stack())
...
>>> another_function()
  File "<doctest>", line 10, in <module>
    another_function()
  File "<doctest>", line 3, in another_function
    lumberstack()
  File "<doctest>", line 6, in lumberstack
    traceback.print_stack()
[('<doctest>', 10, '<module>', 'another_function()'),
 ('<doctest>', 3, 'another_function', 'lumberstack()'),
 ('<doctest>', 7, 'lumberstack', 'print repr(traceback.extract_stack())')]
['  File "<doctest>", line 10, in <module>\n    another_function()\n',
 '  File "<doctest>", line 3, in another_function\n    lumberstack()\n',
 '  File "<doctest>", line 8, in lumberstack\n    print repr(traceback.format_stack())\n']

traceback.extract_stack 的文档字符串与 traceback.extract_tb 的文档字符串相同

traceback.extract_tb(traceback[, limit])

返回最多限制“预处理”堆栈跟踪条目的列表 从 traceback 对象中提取 traceback。它对 堆栈跟踪的替代格式。如果省略limit或None，则全部 条目被提取。 “预处理”的堆栈跟踪条目是 四元组（文件名、行号、函数名、文本）表示 通常为堆栈跟踪打印的信息。文字是 去除了前导和尾随空格的字符串；如果源 不可用，它是无。

Answer 3

你的目标是什么？如果您担心bar 和foo 抛出相同的异常类型而调用者无法区分它们，只需派生一个新的异常类即可：

import random

class FooException(Exception):
    """An exception thrown only by foo."""

def foo():
    if random.randint(1,10) % 2:
        raise FooException

    bar()

def bar():
    raise Exception

try:
    foo()
except FooException:
    print "Exception raised in foo..."
except:
    print "Exception raised in bar (probably)..."