Separating except portion of a try/except into a function

Question

I have a try/except where I repeat the except portion frequently in my code. This led me to believe that it would be better to separate the except portion into a function.

Below is my use case:

try:
  ...
except api.error.ReadError as e:
  ...
except api.error.APIConnectionError as e:
  ...
except Exception as e:
  ...

How would I go about separating this logic into a function so I can do something as simple as:

try:
  ...
except:
  my_error_handling_function(e)

How about making a custom error class so you can just catch a single kind of error? — Andrew Jaffe, Jun 28 '16 at 19:21
You don't have to catch each exception separately if they are handled the same: `except (api.error.ReadError, api.error.APIConnectionError, Exception) as e:` If they aren't handled the same, don't use one function to handle them all. — chepner, Jun 28 '16 at 19:27

m_callens · Accepted Answer · 2016-06-28T19:18:05.300

2

Just define the function:

def my_error_handling(e):
    #Do stuff

...and pass in the exception object as the parameter:

try:
    #some code
except Exception as e:
    my_error_handling(e)

Using just a generic Exception type will allow you to have a single except clause and handle and test for different error types within your handling function.

In order to check for the name of the caught exception, you can get it by doing:

type(e).__name__

Which will print the name, such as ValueError, IOError, etc.

edited Jun 28 '16 at 19:18

answered Jun 28 '16 at 19:09

m_callens

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I understand this part, but I'm not sure what my_error_handling(e) would look like within the context of my 3 use cases – Michael Smith Jun 28 '16 at 19:19
@MichaelSmith you simply do `if` statements to check like `if type(e).__name__ == 'ReadError'` – m_callens Jun 28 '16 at 19:20
This is what I was looking for! Will give it a try soon. – Michael Smith Jun 28 '16 at 19:28

score 0 · Answer 2 · edited May 23 '17 at 11:52

0

Define your function:

def my_error_handling(e):
    #Handle exception

And do what you're proposing:

try:
  ...
except Exception as e:
  my_error_handling_function(e)

You can handle logic by getting the type of the exception 'e' within your function. See: python: How do I know what type of exception occurred?

edited May 23 '17 at 11:52

Community

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answered Jun 28 '16 at 19:12

Checkmate

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You're try/except is not catch is not assigning any value `e` to pass, nor any specified `Exception` type – m_callens Jun 28 '16 at 19:16
But at this point how would my_error_handling function know what logic to execute for the 3 different cases of exceptions? – Michael Smith Jun 28 '16 at 19:17
@MichaelSmith I updated my post to include that checking – m_callens Jun 28 '16 at 19:18
Sorry, forgot to include definition for e. – Checkmate Jun 28 '16 at 19:20

score 0 · Answer 3 · answered Jun 28 '16 at 19:14

I would suggest refactoring your code so the try/except block is only present in a single location.

For instance, an API class with a send() method, seems like a reasonable candidate for containing the error handling logic you have described in your question.

score 0 · Answer 4 · answered Oct 15 '22 at 13:41

If you don't like try-catch statement, you can use exception-decouple package and decorator.

from exception_decouple import redirect_exceptions

def my_error_handling(arg, e):
    #Do stuff

@redirect_exceptions(my_error_handling, api.error.ReadError, api.error.APIConnectionError)
def foo(arg):
    ...

Separating except portion of a try/except into a function

4 Answers4

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