Python 尝试“除其他外”最终返回“除其他外”选项？

我正在开发一个可以引发多个异常的函数。我想在except块中处理这些

异常

，然后返回带有自定义消息和回溯的结果。问题是

最终

是有保证的，所以我不能返回

else

块中的任何内容

如果引发了某些

异常

，则此代码有效，但如果没有

异常

，则此代码无效。在这种情况下，我只想返回

{'success'：True}

因此，从这个代码：

def foo():
    try:
        #some code
        return {'success':True}
    except FirstException:
        tb = traceback.format_exc()
        msg = 'There was FirstExc'
        return {'success':False,
                'tb':tb,
                'msg':msg}
    except SecondException:
        tb = traceback.format_exc()
        msg = 'There was SecondExc'
        return {'success':False,
                'tb':tb,
                'msg':msg}
    ...

我不想重复

返回的内容

。我试过：

def foo():
    try:
        pass
    except FirstException:
        tb = traceback.format_exc()
        msg = 'There was FirstExc'
    except SecondException:
        tb = traceback.format_exc()
        msg = 'There was SecondExc'
    else:
        return {'success':True}
    finally:
        return {'success':False,
                'tb':tb,
                'msg':msg}

你知道怎么做吗？我知道我可以将

return{'success'：True}

放入

try

块中，最后移除

和
else
块，并将
return{'success'：False，'tb'：tb，'msg'：msg}
添加到每个
块中，除了
块之外，还有许多
块，因此代码会重复多次

还有其他选择吗？
不要使用
finally
块。您只想为异常返回
False
，否则返回
True
；在
finally
中返回始终适用于这两种情况

您可以从除
套件之外的两个
套件返回，也可以合并套件

从这两方面返回会导致更多的重复：

def foo():
    try:
        pass
    except FirstException:
        tb = traceback.format_exc()
        msg = 'There was FirstExc'
        return {'success':False,
                'tb':tb,
                'msg':msg}
    except SecondException:
        tb = traceback.format_exc()
        msg = 'There was SecondExc'
        return {'success':False,
                'tb':tb,
                'msg':msg}
    else:
        return {'success':True}

您可以将除
之外的
套件组合为一个套件：

def foo():
    try:
        pass
    except (FirstException, SecondException) as e:
        tb = traceback.format_exc()
        exception_type = 'FirstExc' if isinstance(e, FirstException) else 'SecondExc'
        msg = 'There was {}'.format(exception_type)
        return {'success':False,
                'tb':tb,
                'msg':msg}
    else:
        return {'success':True}

另一个选项是首先构建返回值，然后根据需要添加信息：

def foo():
    result = {'success': True}
    try:
        pass
    except FirstException:
        tb = traceback.format_exc()
        msg = 'There was FirstExc'
        result = {'success': False, 'tb': tb, 'msg': msg}
    except SecondException:
        tb = traceback.format_exc()
        msg = 'There was SecondExc'
        result = {'success': False, 'tb': tb, 'msg': msg}
    finally:
        return result

但是，这与except-suite选项中的
返回
并没有太大区别

def foo():
    success = False
    try:
        pass
    except FirstException:
        tb = traceback.format_exc()
        msg = 'There was FirstExc'
    except SecondException:
        tb = traceback.format_exc()
        msg = 'There was SecondExc'
    else:
        success = True
    finally:
        return {'success':success,
                'tb':tb,
                'msg':msg} if not success else {'success':success}

备选方案：

def foo():
    result = {"success": False}
    try:
        pass
    except FirstException:
        result['tb'] = traceback.format_exc()
        result['msg'] = 'There was FirstExc'
    except SecondException:
        result['tb'] = traceback.format_exc()
        result['msg'] = 'There was SecondExc'
    else:
        result['success'] = True
    finally:
        return result

上述内容略有变化：

def foo():
    result = {"success": False}
    try:
        pass
    except FirstException:
        result.update({'tb': traceback.format_exc(), 'msg': 'There was FirstExc'})
    except SecondException:
        result.update({'tb': traceback.format_exc(), 'msg': 'There was SecondExc'})
    else:
        result['success'] = True
    finally:
        return result

条件表达式使其相当不可读。如果不成功，只需使用
：return{…}
，然后在下一行使用
return{…}
。无需使用
否则：
。将引发NameError@brunodesthuilliers：不会的。如果
success
为
True
，则条件表达式根本不会执行第一部分。但是，由于在最后一行使用了条件表达式，所以很难看到这一点。