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Exceptional Exceptions - EuroPython 2019
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Mario Corchero
July 11, 2019
Programming
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Exceptional Exceptions - EuroPython 2019
Mario Corchero
July 11, 2019
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Transcript
© 2019 Bloomberg Finance L.P. All rights reserved. Exceptional Exceptions:
How to properly raise, handle and create them EuroPython 2019 July 11, 2019 Mario Corchero @mariocj89
© 2018 Bloomberg Finance L.P. All rights reserved. © 2019
Bloomberg Finance L.P. All rights reserved. Let’s just raise an exception, right?
© 2018 Bloomberg Finance L.P. All rights reserved. © 2019
Bloomberg Finance L.P. All rights reserved. Let’s just raise an exception, right?
© 2018 Bloomberg Finance L.P. All rights reserved. © 2019
Bloomberg Finance L.P. All rights reserved. Let’s go step by step
© 2018 Bloomberg Finance L.P. All rights reserved. © 2019
Bloomberg Finance L.P. All rights reserved. How to capture an exception
© 2018 Bloomberg Finance L.P. All rights reserved. © 2019
Bloomberg Finance L.P. All rights reserved. What can go in the except?
© 2018 Bloomberg Finance L.P. All rights reserved. © 2019
Bloomberg Finance L.P. All rights reserved. What can go in the except?
© 2018 Bloomberg Finance L.P. All rights reserved. © 2019
Bloomberg Finance L.P. All rights reserved. Using finally
© 2018 Bloomberg Finance L.P. All rights reserved. © 2019
Bloomberg Finance L.P. All rights reserved. Using else
© 2018 Bloomberg Finance L.P. All rights reserved. © 2019
Bloomberg Finance L.P. All rights reserved. Order of execution?
© 2018 Bloomberg Finance L.P. All rights reserved. © 2019
Bloomberg Finance L.P. All rights reserved. What about returning in the middle?
© 2018 Bloomberg Finance L.P. All rights reserved. © 2019
Bloomberg Finance L.P. All rights reserved. Logging exceptions Use exc_info to include exception information
© 2018 Bloomberg Finance L.P. All rights reserved. © 2019
Bloomberg Finance L.P. All rights reserved. Logging exceptions
© 2018 Bloomberg Finance L.P. All rights reserved. © 2019
Bloomberg Finance L.P. All rights reserved. Logging exceptions Errors should never pass silently. Unless explicitly silenced.
© 2018 Bloomberg Finance L.P. All rights reserved. © 2019
Bloomberg Finance L.P. All rights reserved. Logging exceptions
© 2018 Bloomberg Finance L.P. All rights reserved. © 2019
Bloomberg Finance L.P. All rights reserved. Logging exceptions But... When I have...
© 2018 Bloomberg Finance L.P. All rights reserved. © 2019
Bloomberg Finance L.P. All rights reserved. Logging exceptions But... What if I know...
© 2018 Bloomberg Finance L.P. All rights reserved. © 2019
Bloomberg Finance L.P. All rights reserved. Logging exceptions
© 2018 Bloomberg Finance L.P. All rights reserved. © 2019
Bloomberg Finance L.P. All rights reserved. Logging exceptions
© 2018 Bloomberg Finance L.P. All rights reserved. © 2019
Bloomberg Finance L.P. All rights reserved. Logging exceptions
© 2018 Bloomberg Finance L.P. All rights reserved. © 2019
Bloomberg Finance L.P. All rights reserved. Logging exceptions
© 2018 Bloomberg Finance L.P. All rights reserved. © 2019
Bloomberg Finance L.P. All rights reserved. Scoping of the except See PEP 3110. In short: exception -> traceback -> stack frame -> exception
© 2018 Bloomberg Finance L.P. All rights reserved. © 2019
Bloomberg Finance L.P. All rights reserved. Raise it!
© 2018 Bloomberg Finance L.P. All rights reserved. © 2019
Bloomberg Finance L.P. All rights reserved. The tricky, raise within except
© 2018 Bloomberg Finance L.P. All rights reserved. The tricky,
raise within except
© 2018 Bloomberg Finance L.P. All rights reserved. © 2019
Bloomberg Finance L.P. All rights reserved. Reraise
© 2018 Bloomberg Finance L.P. All rights reserved. Reraise
© 2018 Bloomberg Finance L.P. All rights reserved. © 2019
Bloomberg Finance L.P. All rights reserved. Reraise
© 2018 Bloomberg Finance L.P. All rights reserved. Reraise
© 2018 Bloomberg Finance L.P. All rights reserved. © 2019
Bloomberg Finance L.P. All rights reserved. Chaining exceptions
© 2018 Bloomberg Finance L.P. All rights reserved. Chaining exceptions
© 2018 Bloomberg Finance L.P. All rights reserved. © 2019
Bloomberg Finance L.P. All rights reserved. Eliding previous exception
© 2018 Bloomberg Finance L.P. All rights reserved. © 2019
Bloomberg Finance L.P. All rights reserved. Eliding previous exception
© 2018 Bloomberg Finance L.P. All rights reserved. © 2019
Bloomberg Finance L.P. All rights reserved. False friends: NotImplemented Passes without printing. 37,762 hits in GitHub as of July 2019.
© 2018 Bloomberg Finance L.P. All rights reserved. © 2019
Bloomberg Finance L.P. All rights reserved. Raise on a thread?
© 2018 Bloomberg Finance L.P. All rights reserved. Raise on
a thread?
© 2018 Bloomberg Finance L.P. All rights reserved. © 2019
Bloomberg Finance L.P. All rights reserved. The exception hierarchy Check https://docs.python.org/3/library/exceptions.html
© 2018 Bloomberg Finance L.P. All rights reserved. © 2019
Bloomberg Finance L.P. All rights reserved. Exception attributes
© 2018 Bloomberg Finance L.P. All rights reserved. © 2019
Bloomberg Finance L.P. All rights reserved. Exception attributes
© 2018 Bloomberg Finance L.P. All rights reserved. © 2019
Bloomberg Finance L.P. All rights reserved. Exception attributes
© 2018 Bloomberg Finance L.P. All rights reserved. © 2019
Bloomberg Finance L.P. All rights reserved. Creating new classes
© 2018 Bloomberg Finance L.P. All rights reserved. © 2019
Bloomberg Finance L.P. All rights reserved. Creating new classes
© 2018 Bloomberg Finance L.P. All rights reserved. © 2019
Bloomberg Finance L.P. All rights reserved. Exception hierarchy
© 2018 Bloomberg Finance L.P. All rights reserved. © 2019
Bloomberg Finance L.P. All rights reserved. Multiple inheritance • Decimal: • Requests:
© 2018 Bloomberg Finance L.P. All rights reserved. © 2019
Bloomberg Finance L.P. All rights reserved. Can I use Error codes?
© 2018 Bloomberg Finance L.P. All rights reserved. © 2019
Bloomberg Finance L.P. All rights reserved. Conclusions
© 2018 Bloomberg Finance L.P. All rights reserved. © 2019
Bloomberg Finance L.P. All rights reserved. Extra content!
© 2018 Bloomberg Finance L.P. All rights reserved. © 2019
Bloomberg Finance L.P. All rights reserved. New magic in 3.8
© 2018 Bloomberg Finance L.P. All rights reserved. © 2019
Bloomberg Finance L.P. All rights reserved. New magic in 3.8
© 2019 Bloomberg Finance L.P. All rights reserved. Cycles when
reraising
© 2019 Bloomberg Finance L.P. All rights reserved. Cycles when
reraising
© 2018 Bloomberg Finance L.P. All rights reserved. © 2019
Bloomberg Finance L.P. All rights reserved. Returns in finally
© 2018 Bloomberg Finance L.P. All rights reserved. © 2019
Bloomberg Finance L.P. All rights reserved. Returns in finally
© 2018 Bloomberg Finance L.P. All rights reserved. © 2019
Bloomberg Finance L.P. All rights reserved. Returns in finally
© 2019 Bloomberg Finance L.P. All rights reserved. Thank you!
Questions?? Also, ask me about travelling to Extremadura!