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Exceptional Exceptions - EuroPython 2019

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Avatar for Mario Corchero Mario Corchero
July 11, 2019
Programming
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Exceptional Exceptions - EuroPython 2019

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Mario Corchero

July 11, 2019
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Transcript

  1. © 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

  2. © 2018 Bloomberg Finance L.P. All rights reserved. © 2019

    Bloomberg Finance L.P. All rights reserved. Let’s just raise an exception, right?

  3. © 2018 Bloomberg Finance L.P. All rights reserved. © 2019

    Bloomberg Finance L.P. All rights reserved. Let’s just raise an exception, right?

  4. © 2018 Bloomberg Finance L.P. All rights reserved. © 2019

    Bloomberg Finance L.P. All rights reserved. Let’s go step by step

  5. © 2018 Bloomberg Finance L.P. All rights reserved. © 2019

    Bloomberg Finance L.P. All rights reserved. How to capture an exception

  6. © 2018 Bloomberg Finance L.P. All rights reserved. © 2019

    Bloomberg Finance L.P. All rights reserved. What can go in the except?

  7. © 2018 Bloomberg Finance L.P. All rights reserved. © 2019

    Bloomberg Finance L.P. All rights reserved. What can go in the except?

  8. © 2018 Bloomberg Finance L.P. All rights reserved. © 2019

    Bloomberg Finance L.P. All rights reserved. Using finally

  9. © 2018 Bloomberg Finance L.P. All rights reserved. © 2019

    Bloomberg Finance L.P. All rights reserved. Using else

  10. © 2018 Bloomberg Finance L.P. All rights reserved. © 2019

    Bloomberg Finance L.P. All rights reserved. Order of execution?

  11. © 2018 Bloomberg Finance L.P. All rights reserved. © 2019

    Bloomberg Finance L.P. All rights reserved. What about returning in the middle?

  12. © 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

  13. © 2018 Bloomberg Finance L.P. All rights reserved. © 2019

    Bloomberg Finance L.P. All rights reserved. Logging exceptions

  14. © 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.

  15. © 2018 Bloomberg Finance L.P. All rights reserved. © 2019

    Bloomberg Finance L.P. All rights reserved. Logging exceptions

  16. © 2018 Bloomberg Finance L.P. All rights reserved. © 2019

    Bloomberg Finance L.P. All rights reserved. Logging exceptions But... When I have...

  17. © 2018 Bloomberg Finance L.P. All rights reserved. © 2019

    Bloomberg Finance L.P. All rights reserved. Logging exceptions But... What if I know...

  18. © 2018 Bloomberg Finance L.P. All rights reserved. © 2019

    Bloomberg Finance L.P. All rights reserved. Logging exceptions

  19. © 2018 Bloomberg Finance L.P. All rights reserved. © 2019

    Bloomberg Finance L.P. All rights reserved. Logging exceptions

  20. © 2018 Bloomberg Finance L.P. All rights reserved. © 2019

    Bloomberg Finance L.P. All rights reserved. Logging exceptions

  21. © 2018 Bloomberg Finance L.P. All rights reserved. © 2019

    Bloomberg Finance L.P. All rights reserved. Logging exceptions

  22. © 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

  23. © 2018 Bloomberg Finance L.P. All rights reserved. © 2019

    Bloomberg Finance L.P. All rights reserved. Raise it!

  24. © 2018 Bloomberg Finance L.P. All rights reserved. © 2019

    Bloomberg Finance L.P. All rights reserved. The tricky, raise within except

  25. © 2018 Bloomberg Finance L.P. All rights reserved. The tricky,

    raise within except

  26. © 2018 Bloomberg Finance L.P. All rights reserved. © 2019

    Bloomberg Finance L.P. All rights reserved. Reraise

  27. © 2018 Bloomberg Finance L.P. All rights reserved. Reraise

  28. © 2018 Bloomberg Finance L.P. All rights reserved. © 2019

    Bloomberg Finance L.P. All rights reserved. Reraise

  29. © 2018 Bloomberg Finance L.P. All rights reserved. Reraise

  30. © 2018 Bloomberg Finance L.P. All rights reserved. © 2019

    Bloomberg Finance L.P. All rights reserved. Chaining exceptions

  31. © 2018 Bloomberg Finance L.P. All rights reserved. Chaining exceptions

  32. © 2018 Bloomberg Finance L.P. All rights reserved. © 2019

    Bloomberg Finance L.P. All rights reserved. Eliding previous exception

  33. © 2018 Bloomberg Finance L.P. All rights reserved. © 2019

    Bloomberg Finance L.P. All rights reserved. Eliding previous exception

  34. © 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.

  35. © 2018 Bloomberg Finance L.P. All rights reserved. © 2019

    Bloomberg Finance L.P. All rights reserved. Raise on a thread?

  36. © 2018 Bloomberg Finance L.P. All rights reserved. Raise on

    a thread?

  37. © 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

  38. © 2018 Bloomberg Finance L.P. All rights reserved. © 2019

    Bloomberg Finance L.P. All rights reserved. Exception attributes

  39. © 2018 Bloomberg Finance L.P. All rights reserved. © 2019

    Bloomberg Finance L.P. All rights reserved. Exception attributes

  40. © 2018 Bloomberg Finance L.P. All rights reserved. © 2019

    Bloomberg Finance L.P. All rights reserved. Exception attributes

  41. © 2018 Bloomberg Finance L.P. All rights reserved. © 2019

    Bloomberg Finance L.P. All rights reserved. Creating new classes

  42. © 2018 Bloomberg Finance L.P. All rights reserved. © 2019

    Bloomberg Finance L.P. All rights reserved. Creating new classes

  43. © 2018 Bloomberg Finance L.P. All rights reserved. © 2019

    Bloomberg Finance L.P. All rights reserved. Exception hierarchy

  44. © 2018 Bloomberg Finance L.P. All rights reserved. © 2019

    Bloomberg Finance L.P. All rights reserved. Multiple inheritance • Decimal: • Requests:

  45. © 2018 Bloomberg Finance L.P. All rights reserved. © 2019

    Bloomberg Finance L.P. All rights reserved. Can I use Error codes?

  46. © 2018 Bloomberg Finance L.P. All rights reserved. © 2019

    Bloomberg Finance L.P. All rights reserved. Conclusions

  47. © 2018 Bloomberg Finance L.P. All rights reserved. © 2019

    Bloomberg Finance L.P. All rights reserved. Extra content!

  48. © 2018 Bloomberg Finance L.P. All rights reserved. © 2019

    Bloomberg Finance L.P. All rights reserved. New magic in 3.8

  49. © 2018 Bloomberg Finance L.P. All rights reserved. © 2019

    Bloomberg Finance L.P. All rights reserved. New magic in 3.8

  50. © 2019 Bloomberg Finance L.P. All rights reserved. Cycles when

    reraising

  51. © 2019 Bloomberg Finance L.P. All rights reserved. Cycles when

    reraising

  52. © 2018 Bloomberg Finance L.P. All rights reserved. © 2019

    Bloomberg Finance L.P. All rights reserved. Returns in finally

  53. © 2018 Bloomberg Finance L.P. All rights reserved. © 2019

    Bloomberg Finance L.P. All rights reserved. Returns in finally

  54. © 2018 Bloomberg Finance L.P. All rights reserved. © 2019

    Bloomberg Finance L.P. All rights reserved. Returns in finally

  55. © 2019 Bloomberg Finance L.P. All rights reserved. Thank you!

    Questions?? Also, ask me about travelling to Extremadura!