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What happens when you mess with hashing in Python | Aaron Meurer's Blog #9

Open utterances-bot opened 3 years ago

utterances-bot commented 3 years ago

What happens when you mess with hashing in Python | Aaron Meurer's Blog

https://asmeurer.com/blog/posts/what-happens-when-you-mess-with-hashing-in-python/

asmeurer commented 3 years ago

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asmeurer commented 3 years ago

These are the original comments on this post that were made when this blog used the Disqus blog system.

Comment from bjd2385 on 2016-08-28 12:33:12+00:00:

Very interesting post. I was just looking into hash functions (I've never formally learned what the topic entails), and since I'm most familiar with Python this post explained quite a bit, especially your early mathematical points.

Comment from Mark Lawrence on 2016-10-03 20:26:54+00:00:

At what point does Python 3 force the override of __hash__ if you've defined __eq__? E.g when would your

AlwaysEqual class fail?

Replies:

Comment from asmeurer on 2016-10-03 20:38:13+00:00:

That's a good catch. I originally wrote this post in Python 2. The example does indeed fail in Python 3. More specifically, if you override __eq__, Python 3 automatically sets __hash__ to None. I'll update the post to make this more clear.

Comment from Erick Mendonça on 2017-07-30 03:23:55+00:00:

Great article! We must really pay attention to these details when implementing custom hashes.

Comment from Ignacio on 2017-10-07 22:31:56+00:00:

Thanks a lot for this post! Clarified a lot of concepts.