When debugging Python code at the interactive prompt (REPL), often I'll write some code which raises an exception, but I haven't wrapped it in a try/except, so once the error is raised, I've forever lost the exception object.
在交互式提示符（REPL）上调试Python代码时，我经常会编写一些引发异常的代码，但是我没有把它包装在try / except中，所以一旦出现错误，我就永远失去了异常对象。
Often the traceback and error message Python prints out isn't enough. For example, when fetching a URL, the server might return a 40x error, and you need the content of the response via error.read() ... but you haven't got the error object anymore. For example:
通常Python打印出来的追溯和错误消息是不够的。例如，在获取URL时，服务器可能会返回40x错误，并且您需要通过error.read（）进行响应的内容...但是您还没有得到错误对象。例如：
>>> import urllib2
>>> f = urllib2.urlopen('http://example.com/api/?foo=bad-query-string')
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
...
urllib2.HTTPError: HTTP Error 400: Bad Request
Drat, what did the body of the response say? It probably had valuable error information in it...
Drat，回应的主体说了什么？它可能包含有价值的错误信息......
I realize it's usually easy to re-run your code wrapped in a try/except, but that's not ideal. I also realize that in this specific case if I were using the requests library (which doesn't raise for HTTP errors), I wouldn't have this problem ... but I'm really wondering if there's a more general way to get the last exception object at a Python prompt in these cases.
我意识到重新运行包含在try / except中的代码通常很容易，但这并不理想。我也意识到在这种特殊情况下，如果我使用请求库（不会引起HTTP错误），我就不会有这个问题...但我真的想知道是否有更通用的方法来获取在这些情况下，Python提示符下的最后一个异常对象。
2 个解决方案
#1
50
The sys module provides some functions for post-hoc examining of exceptions: sys.last_type, sys.last_value, and sys.last_traceback.
sys模块提供了一些用于事后检查异常的函数：sys.last_type，sys.last_value和sys.last_traceback。
sys.last_value is the one you're looking for.
sys.last_value是您正在寻找的。
#2
8
As @Cairnarvon mentioned, I didn't find any last_valuemember is sys module.
正如@Cairnarvon所提到的，我没有发现任何last_valuemember是sys模块。
sys.exc_info() did the trick for me. sys.exc_info() returns a tuple with three values (type, value, traceback).
sys.exc_info（）为我做了伎俩。 sys.exc_info（）返回一个包含三个值（类型，值，跟踪）的元组。
So sys.exc_info()[1] will give the readable error. Here is the example,
所以sys.exc_info（）[1]会给出可读错误。这是一个例子，
import sys
list = [1,2,3,4]
try:
del list[8]
except Exception:
print(sys.exc_info()[1])
will output list assignment index out of range
将输出列表分配索引超出范围
Also, traceback.format_exc() from traceback module can be used to print out the similar information.
此外，traceback模块中的traceback.format_exc（）可用于打印出类似的信息。
Below is the output if fortmat_exec() is used,
如果使用fortmat_exec（），下面是输出，
Traceback (most recent call last): File "python", line 6, in <module> IndexError: list assignment index out of range
Traceback（最近一次调用最后一次）：文件“python”，第6行，在
#1
50
The sys module provides some functions for post-hoc examining of exceptions: sys.last_type, sys.last_value, and sys.last_traceback.
sys模块提供了一些用于事后检查异常的函数：sys.last_type，sys.last_value和sys.last_traceback。
sys.last_value is the one you're looking for.
sys.last_value是您正在寻找的。
#2
8
As @Cairnarvon mentioned, I didn't find any last_valuemember is sys module.
正如@Cairnarvon所提到的，我没有发现任何last_valuemember是sys模块。
sys.exc_info() did the trick for me. sys.exc_info() returns a tuple with three values (type, value, traceback).
sys.exc_info（）为我做了伎俩。 sys.exc_info（）返回一个包含三个值（类型，值，跟踪）的元组。
So sys.exc_info()[1] will give the readable error. Here is the example,
所以sys.exc_info（）[1]会给出可读错误。这是一个例子，
import sys
list = [1,2,3,4]
try:
del list[8]
except Exception:
print(sys.exc_info()[1])
will output list assignment index out of range
将输出列表分配索引超出范围
Also, traceback.format_exc() from traceback module can be used to print out the similar information.
此外，traceback模块中的traceback.format_exc（）可用于打印出类似的信息。
Below is the output if fortmat_exec() is used,
如果使用fortmat_exec（），下面是输出，
Traceback (most recent call last): File "python", line 6, in <module> IndexError: list assignment index out of range
Traceback（最近一次调用最后一次）：文件“python”，第6行，在