try-except 块：如果引发异常，则类似于“else”

Question

我有这样的代码：

try:
    return make_success_result()
except FirstException:
    handle_first_exception()
    return make_error_result()
except SecondException:
    handle_second_exception()
    return make_error_result()

我想知道有什么办法可以做到这一点：

try:
    # do something
except Error1:
    # do Error1 specific handling
except Error2:
    # do Error2 specific handling
else:
    # do this if there was no exception
????:
    # ALSO do this if there was ANY of the listed exceptions (e.g. some common error handling)

因此，代码按以下序列之一执行：

try > else > finally
try > except > ???? > finally

编辑：我的观点是???? 块应该在任何一个except块之后立即执行，这意味着它是对错误处理的补充，而不是替代。

Answer 1

在这种情况下我要做的是在你得到异常时设置一个布尔值，如下所示：

got_exception = False
try:
    # do something
except Error1:
    # do Error1 specific handling
    got_exception = True
except Error2:
    # do Error2 specific handling
    got_exception = True
else:
    # If there was no exception
finally:
    if got_exception:
        # ALSO do this if there was ANY exception (e.g. some common error handling)

这应该符合您的需求，这是IMO最简单的方法，将所有已呈现的解决方案组合到最易于调试的最易读的代码结构中。

Answer 2

你可以做：

try:
    # Do something
except Error1:
    # Do Error1 specific handling
except Error2:
    # Do Error2 specific handling
except Exception:
    # Handle any other exception (Generic exception handling)
else:
    # Do this if there were no exceptions
finally:
    # Execute this regardless

Answer 3

你实际上可以这样做：

try:
    print 'try'
    # 1/0
    # {}[1]
    # {}.a
except AttributeError, KeyError:  # only handle these exceptions..
    try:
        raise                     # re-raise the exception so we can add a finally-clause executing iff there was an exception.
    except AttributeError:
        print 'attrerr'
        # raise ...               # any raises here will also execute 'common'
    except KeyError:
        print 'keyerror'
    finally:                      # update 0: you wanted the common code after the exceptions..
        print "common"

else:
    print 'no exception'

但它是可怕的，我不建议你没有大量的评论描述为什么..

更新：除了内部try-block中的有趣异常之外，您不需要捕获任何内容。 代码已更新。

UPDATE2：根据OP的说明，当抛出一个有趣的异常时，应该执行common 。 代码已更新。 @MatTaylor的版本绝对是要走的路;-)

Answer 4

是的，python中的异常处理包括else和finally子句。 你可以这样做：

try:
    # do something
except Error1:
    # do Error1 specific handling
except Error2:
    # do Error2 specific handling
else:
    # do this if there was no exception
finally:
    # Do this in any case!

python文档提到了这些块，即使它没有显示您需要的完整示例。

---

编辑：我看到你没有专门要求清理一般情况。 Python文档就是这样说的：

try语句有另一个可选子句，用于定义必须在所有情况下执行的清理操作。

请注意， finally将运行是否存在异常。 结合else块，你仍然可以做你想要的。

Answer 5

您可以捕获所有错误并在错误处理代码中检查其类型，如下所示：

try:
    # do something
except Exception as e:
    if isinstance(e, Error1):
        # do Error1 specific handling
    elif isinstance(e, Error2):
        # do Error2 specific handling
    else:
        # do non-Error1/Error2 handling
    # ALSO do this if there was ANY exception (e.g. some common error handling)
else:
    # do this if there was no exception