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Python

Posted by Christian Vasquez
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Christian Vasquez
Python Development Techdegree Student 820 Points

When to use "as err" for an exception

I'm having trouble knowing when to use the "as err" for an exception. For the section "Practice Creating and Using Functions in Python", I'm doing the 2nd objective in "Use an External Function", and I didn't use the "as err" for the "CommunicationError" and my work got accepted. But when I moved on to the 3rd objective, I had to use the "as err" for the "MessageTooLongError" because my work wasn't being accepted without it. Is it safe to say that I should just use the "as err" every time I have an exception?

try:
    tweet(message)
except CommunicationError:
    print("An error occurred attempting to connect to Twitter. Please try again!")
except MessageTooLongError as err:
    print("Oh no! Your message was too long (...){}".format(err))

1 Answer

Chris Freeman
MOD
Chris Freeman
Treehouse Moderator 68,441 Points
Chris Freeman
Chris Freeman
Treehouse Moderator 68,441 Points

Good question! You would use the as err when you needed to access the object containing information about the error.

In the first case, you only needed to know that the error was raised and no specifics about what caused it.

In the second case, you wanted to print the specific message detailing the error. For this second case, you needed a reference to the error object so as err was used.

Note that err is just a name chosen. You could use any legal variable name here. You might see some code use as e.

Post back if you need more help. Good luck!!