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[英]Python Debugging : Find where an exception is raised, go into debug mode?
[英]How in Python find where exception was raised
如何确定引发了什么函数异常。 例如,存在两个函数:'foo'和'bar'。 在'foo'中,异常将随机提出。
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" % ???
import inspect
try:
foo()
except Exception as e:
print "Exception raised in %s" % inspect.trace()[-1][3]
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
如果代码从文件运行,则回溯将告诉错误发生的位置的行和字符数:)
编辑:
为了适应Habibutsu的评论: Yes, it's useful for printing, but when needed to get more info (for example function name) - not suitable
doc-pages告诉你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']
该DOC-字符串traceback.extract_stack
是相同traceback.extract_tb
traceback.extract_tb(traceback [,limit])
返回最多限制从回溯对象回溯中提取的“预处理”堆栈跟踪条目的列表。 它对堆栈跟踪的替代格式化很有用。 如果省略limit或None,则提取所有条目。 “预处理”堆栈跟踪条目是四倍(文件名,行号,函数名称,文本),表示通常为堆栈跟踪打印的信息。 文本是一个带有前导和尾随空格的字符串; 如果源不可用则为None。
你的目标是什么? 如果你担心bar
和foo
抛出相同的异常类型并且调用者无法区分它们,那么只需派生一个新的异常类:
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)..."
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