CODEWITHSUNDEEP
pythonpython-3.xexceptionerror-handlingtry-catch
Halal Memoirs
Halal Memoirs

Reputation: 25

Why does my message for exception not change with my if statement

I currently have the following code which throws an error on exception just how i want:

try:
    something ....

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

However in some cases if I get a specific exception such as:

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

I want to change the message of e in the exception to what i want.. how would i go about this?

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

but it doesnt seem to be working

Upvotes: 1

Views: 50

Answers (1)

Still.Tony
Still.Tony

Reputation: 1434

Try catching the type of error instead of parsing the text of the error.

More info can be found at Handling Exceptions section of Python help but to be fully thorough (because I feel dumb for initially answering a Python question in C#) you can sort out what exception type you're looking for with something like this:

>>> # 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'

Where ValueError is the error type you need to catch.

More realistically, you can incorporate figuring it your uncaught error types into your program and (hopefully) identify them during testing:

>>> 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'

Once you identify a new error type, add a specific handler for it:

>>> 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

Original (completely useless) answer kept here for posterity (and so the comments make sense)...

Try catching the type of error instead of parsing the text of the error.

e.g.

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;

}

which is copied directly from here: Microsoft try-catch (C# Reference)

Upvotes: 1

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