这是我在Python 2.7和3中用来修改异常消息的函数。X，同时保留原始的回溯。需要6个

def reraise_modify(caught_exc, append_msg, prepend=False):
    """Append message to exception while preserving attributes.

    Preserves exception class, and exception traceback.

    Note:
        This function needs to be called inside an except because
        `sys.exc_info()` requires the exception context.

    Args:
        caught_exc(Exception): The caught exception object
        append_msg(str): The message to append to the caught exception
        prepend(bool): If True prepend the message to args instead of appending

    Returns:
        None

    Side Effects:
        Re-raises the exception with the preserved data / trace but
        modified message
    """
    ExceptClass = type(caught_exc)
    # Keep old traceback
    traceback = sys.exc_info()[2]
    if not caught_exc.args:
        # If no args, create our own tuple
        arg_list = [append_msg]
    else:
        # Take the last arg
        # If it is a string
        # append your message.
        # Otherwise append it to the
        # arg list(Not as pretty)
        arg_list = list(caught_exc.args[:-1])
        last_arg = caught_exc.args[-1]
        if isinstance(last_arg, str):
            if prepend:
                arg_list.append(append_msg + last_arg)
            else:
                arg_list.append(last_arg + append_msg)
        else:
            arg_list += [last_arg, append_msg]
    caught_exc.args = tuple(arg_list)
    six.reraise(ExceptClass,
                caught_exc,
                traceback)

如果你足够幸运只支持python 3。X，这真的变成了一件美丽的事情:)

提高从

我们可以使用raise from链接异常。

try:
    1 / 0
except ZeroDivisionError as e:
    raise Exception('Smelly socks') from e

在这种情况下，调用者将捕获的异常具有引发异常的位置的行号。

Traceback (most recent call last):
  File "test.py", line 2, in <module>
    1 / 0
ZeroDivisionError: division by zero

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "test.py", line 4, in <module>
    raise Exception('Smelly socks') from e
Exception: Smelly socks

注意，底部异常只有我们引发异常的堆栈跟踪。调用者仍然可以通过访问他们捕获的异常的__cause__属性来获得原始异常。

with_traceback

或者你可以使用with_traceback。

try:
    1 / 0
except ZeroDivisionError as e:
    raise Exception('Smelly socks').with_traceback(e.__traceback__)

使用这种形式，调用者将捕获的异常具有原始错误发生位置的回溯。

Traceback (most recent call last):
  File "test.py", line 2, in <module>
    1 / 0
ZeroDivisionError: division by zero

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "test.py", line 4, in <module>
    raise Exception('Smelly socks').with_traceback(e.__traceback__)
  File "test.py", line 2, in <module>
    1 / 0
Exception: Smelly socks

注意，底部的异常中有执行无效除法的行，也有重新引发异常的行。

上面提出的许多解决方案再次引发异常，这被认为是一种糟糕的做法。像这样简单的东西就可以了

try:
    import settings
except ModuleNotFoundError:
    print("Something meaningfull\n")
    raise 

因此，您将首先打印错误消息，然后引发堆栈跟踪，或者您可以简单地通过sys.exit(1)退出，而根本不显示错误消息。

It seems all the answers are adding info to e.args[0], thereby altering the existing error message. Is there a downside to extending the args tuple instead? I think the possible upside is, you can leave the original error message alone for cases where parsing that string is needed; and you could add multiple elements to the tuple if your custom error handling produced several messages or error codes, for cases where the traceback would be parsed programmatically (like via a system monitoring tool).

## Approach #1, if the exception may not be derived from Exception and well-behaved:

def to_int(x):
    try:
        return int(x)
    except Exception as e:
        e.args = (e.args if e.args else tuple()) + ('Custom message',)
        raise

>>> to_int('12')
12

>>> to_int('12 monkeys')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 3, in to_int
ValueError: ("invalid literal for int() with base 10: '12 monkeys'", 'Custom message')

or

## Approach #2, if the exception is always derived from Exception and well-behaved:

def to_int(x):
    try:
        return int(x)
    except Exception as e:
        e.args += ('Custom message',)
        raise

>>> to_int('12')
12

>>> to_int('12 monkeys')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 3, in to_int
ValueError: ("invalid literal for int() with base 10: '12 monkeys'", 'Custom message')

你能看出这种方法的缺点吗?

使用的错误消息引发新的异常

raise Exception('your error message')

or

raise ValueError('your error message')

在你想要引发它或使用'from'将错误消息附加(替换)到当前异常的地方(Python 3。只支持X):

except ValueError as e:
  raise ValueError('your message') from e

这是我在Python 2.7和3中用来修改异常消息的函数。X，同时保留原始的回溯。需要6个

def reraise_modify(caught_exc, append_msg, prepend=False):
    """Append message to exception while preserving attributes.

    Preserves exception class, and exception traceback.

    Note:
        This function needs to be called inside an except because
        `sys.exc_info()` requires the exception context.

    Args:
        caught_exc(Exception): The caught exception object
        append_msg(str): The message to append to the caught exception
        prepend(bool): If True prepend the message to args instead of appending

    Returns:
        None

    Side Effects:
        Re-raises the exception with the preserved data / trace but
        modified message
    """
    ExceptClass = type(caught_exc)
    # Keep old traceback
    traceback = sys.exc_info()[2]
    if not caught_exc.args:
        # If no args, create our own tuple
        arg_list = [append_msg]
    else:
        # Take the last arg
        # If it is a string
        # append your message.
        # Otherwise append it to the
        # arg list(Not as pretty)
        arg_list = list(caught_exc.args[:-1])
        last_arg = caught_exc.args[-1]
        if isinstance(last_arg, str):
            if prepend:
                arg_list.append(append_msg + last_arg)
            else:
                arg_list.append(last_arg + append_msg)
        else:
            arg_list += [last_arg, append_msg]
    caught_exc.args = tuple(arg_list)
    six.reraise(ExceptClass,
                caught_exc,
                traceback)