python - 为什么我的异常消息不会随着我的 if 语句而改变

Question

我目前有以下代码，它会按照我想要的方式抛出异常错误:

try:
    something ....

except Exception as e:
            print(
                'You have encountered the following in the main function \n ERROR: {}'.format(e))

但是在某些情况下，如果我遇到特定异常，例如:

invalid literal for int() with base 10: ''

我想将异常中的 e 消息更改为我想要的..我该怎么做？

If e == "invalid literal for int() with base 10: ''":
   e = 'my new message'
   print(e)

但它似乎没有工作

Answer 1

try catch 错误的类型，而不是解析错误的文本。

更多信息请访问 Handling Exceptions section of Python help但要彻底彻底(因为我最初在 C# 中回答 Python 问题时觉得很愚蠢)，您可以使用以下内容来整理您正在寻找的异常类型:

>>> # Create the error
>>> int('3.6')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: invalid literal for int() with base 10: '3.6'

在哪里 值错误 是您需要捕获的错误类型。

更现实地说，您可以将 Uncaught Error 类型纳入您的程序并(希望)在测试期间识别它们:

>>> try:
... # something ....
...   int('3.6') # for the example, we'll generate error on purpose
... # Assume we've already figured out what to do with these 3 errors
... except (RuntimeError, TypeError, NameError):
...   print("We know what to do with these errors")
... # Our generic except to catch unhandled errors.
... except:
...   print("Unhandled error: {0}".format(err))

Traceback (most recent call last):
  File "<stdin>", line 2, in <module>
ValueError: invalid literal for int() with base 10: '3.6'

确定新的错误类型后，为其添加特定的处理程序:

>>> try:
... # something ....
...   int('3.6')
... except (RuntimeError, TypeError, NameError):
...   print("We know what to do with these errors")
... # The newly added handler for ValueError type
... except ValueError:
...   print("And now we know what to do with a ValueError")
...   print("My new message")
... except:
...   print("Unhandled error: {0}".format(err))

And now we know what to do with a ValueError
My new message

原始(完全没用)的答案留在这里供后代使用(所以评论很有意义)......

try catch 错误的类型，而不是解析错误的文本。

例如

catch (FileNotFoundException e)
{
    // FileNotFoundExceptions are handled here.
}
catch (IOException e)
{
    // Extract some information from this exception, and then
    // throw it to the parent method.
    if (e.Source != null)
        Console.WriteLine("IOException source: {0}", e.Source);
    throw;

}

直接从这里复制:
Microsoft try-catch (C# Reference)