pylint doesn't understand the scope of except clause variables

[pylint-bot]

Originally reported by: Tom Dryer (BitBucket: tdryer, GitHub: @tdryer?)

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In the following code, pylint fails to identify that the e in the except clause is an unused variable, and that the e in print(e) is an undefined variable:

#!python

def main():
    try:
        raise ValueError
    except ValueError as e:
        pass

    print(e)


main()

The issue appears to be that pylint doesn't understand that the scope of the exception variable is limited to the except clause.

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• Bitbucket: https://bitbucket.org/logilab/pylint/issue/626

[pylint-bot]

Original comment by Sylvain Thénault (BitBucket: sthenault, GitHub: @sthenault?):

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The scope of 'e' is actually not limited to the except clause (try running your code, it's perfectly fine). Though pylint should issue 'used-before-assignment' because there will be a bug in case where the exception isn't raised.

[pylint-bot]

Original comment by Tom Dryer (BitBucket: tdryer, GitHub: @tdryer?):

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Oh, this seems to be specific to Python 3. In Python 2 the code works, but in 3.4 it will raise UnboundLocalError.

[pylint-bot]

Original comment by Sylvain Thénault (BitBucket: sthenault, GitHub: @sthenault?):

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Oh right, I missed that part from https://www.python.org/dev/peps/pep-3110/

[pylint-bot]

Original comment by Claudiu Popa (BitBucket: PCManticore, GitHub: @PCManticore):

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This should definitely be fixed.