你可以像Lauritz推荐的那样开始:

except Exception as ex:

然后像这样打印ex:

try:
    #your try code here
except Exception as ex:
    print ex

获取异常对象所属类的名称:

e.__class__.__name__

使用print_exc()函数也将打印堆栈跟踪，这是任何错误消息的基本信息。

是这样的:

from traceback import print_exc

class CustomException(Exception): pass

try:
    raise CustomException("hi")
except Exception as e:
    print ('type is:', e.__class__.__name__)
    print_exc()
    # print("exception happened!")

你会得到这样的输出:

type is: CustomException
Traceback (most recent call last):
  File "exc.py", line 7, in <module>
    raise CustomException("hi")
CustomException: hi

在打印和分析之后，代码可以决定不处理异常，只执行raise:

from traceback import print_exc

class CustomException(Exception): pass

def calculate():
    raise CustomException("hi")

try:
    calculate()
except CustomException as e:
    # here do some extra steps in case of CustomException
    print('custom logic doing cleanup and more')
    # then re raise same exception
    raise

输出:

custom logic doing cleanup and more

和解释器打印异常:

Traceback (most recent call last):
  File "test.py", line 9, in <module>
    calculate()
  File "test.py", line 6, in calculate
    raise CustomException("hi")
__main__.CustomException: hi

引发后，原始异常继续向上传播调用堆栈。(注意可能的陷阱)如果你引发新的异常，它会携带新的(更短的)堆栈跟踪。

from traceback import print_exc

class CustomException(Exception):
    def __init__(self, ok):
        self.ok = ok

def calculate():
    raise CustomException(False)

try:
    calculate()
except CustomException as e:
    if not e.ok:
        # Always use `raise` to rethrow exception
        # following is usually mistake, but here we want to stress this point
        raise CustomException(e.ok)
    print("handling exception")

输出:

Traceback (most recent call last):
  File "test.py", line 13, in <module>
    raise CustomException(e.message)
__main__.CustomException: hi    

注意traceback如何不包括第9行中的compute()函数，这是原始异常e的起源。

实际的异常可以通过以下方式捕获:

try:
    i = 1/0
except Exception as e:
    print e

您可以从Python教程中了解有关异常的更多信息。

你的问题是:“我如何才能确切地看到someFunction()中发生了什么导致异常发生?”

在我看来，您不是在问如何处理生产代码中不可预见的异常(正如许多答案所假设的那样)，而是在问如何找出在开发过程中导致特定异常的原因。

最简单的方法是使用调试器，该调试器可以在未捕获异常发生的地方停止，最好不要退出，以便您可以检查变量。例如，Eclipse开源IDE中的PyDev可以做到这一点。要在Eclipse中启用该功能，请打开Debug透视图，在Run菜单中选择管理Python异常断点，并在未捕获的异常上检查挂起。

大多数答案指向except(…)as(…):语法(正确)，但同时没有人想谈论房间里的大象，而大象是sys.exc_info()函数。 来自sys模块的文档(重点是我的):

This function returns a tuple of three values that give information about the exception that is currently being handled. (…) If no exception is being handled anywhere on the stack, a tuple containing three None values is returned. Otherwise, the values returned are (type, value, traceback). Their meaning is: type gets the type of the exception being handled (a subclass of BaseException); value gets the exception instance (an instance of the exception type); traceback gets a traceback object (see the Reference Manual) which encapsulates the call stack at the point where the exception originally occurred.

我认为sys.exc_info()可以被视为对原始问题“我如何知道发生了什么类型的异常?”的最直接答案。

使用类型class和as语句

try:#code
except Exception as e:
     m=type(e)
     #m is the class of the exception
     strm=str(m)
     #strm is the string of m