Amandine Lee Passing Exceptions 101 Paradigms in Error Handling PyCon 2017

"Speaker: Amandine Lee
Exception handling in Python can sometimes feel like a Wild West. If you have a `send_email` function, and the caller inputs an invalid email address, should it:
A) Return `None` or some other special return value,
B) Let the underlying exception it might cause bubble up,
C) Check via a regex and type checking and raise a `ValueError` immediately, or
D) Make a custom `EmailException` subclass and raise that?
What if there is a network error while the email was sending? Or what if the function calls a helper `_format_email` that returns an integer (clearly wrong!), or raises an `TypeError` itself? Should it crash the program or prompt a retry?
This talk will introduce the concept of an exception, explain the built-in Python exception hierarchy and the utility of custom subclasses, demonstrate try/except/finally/else syntax, and then explore different design patterns for exception control flow and their tradeoffs using examples. It will also make comparisons to error handling philosophy in other languages, like Eiffel and Go.
Slides can be found at: speakerdeck.com/pycon2017 and github.com/PyCon/2017-slides"

[@stalinthomas9850]

00:51 Introduction 03:17 Exception 06:35 Reasons for exceptions 09:52 Exception use cases 13:46 Design by Contract 17:42 Recovering from errors 23:49 Lessons Learned 25:29 QnA

[@Ryndae-l]

It's a shame that there was no talk about the Common Lisp condition system, which I think you can take inspiration from, seeing that python is already a dynamic language and has closures support...

[@hardkrash]

The last data i read about the “try/catch” vs. “if in” for performance was around 10% or less of your tests are going to hit then use try/catch. Unfortunately I can’t find that reference.

[@Ryndae-l]

You can catch a SyntaxError coming from an import, from eval, etc. But yeah, you can't catch it if your error is in the same module, because the module code hasn't even started to run when the error is emited.

[@piertoni]

This talk Is understandable with 0.75 speed option :)

[@RoamingAdhocrat]

I like to think that in her free time, the speaker pursues her passion of being an auctioneer...

[@amandinelee4962]

@@RoamingAdhocrat I've thought about it :) Or impressively fast rapping.