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Created on 2016-09-23 23:23 by Roy Williams, last changed 2022-04-11 14:58 by admin. This issue is now closed.
| Messages (3) | |||
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| msg277305 - (view) | Author: Roy Williams (Roy Williams) * | Date: 2016-09-23 23:23 | |
I'm finding the -3 flag to be super useful at identifying problems with code when porting to Python 3. One of the most common failures, however, is "DeprecationWarning: Overriding __eq__ blocks inheritance of __hash__ in 3.x". While implementing __eq__ without implementing __hash__ is very much an anti-pattern, this warning would be much less noisy if it could be thrown at time of access (like the __getslice__ warning) instead of time of declaration. See Also: https://github.com/nedbat/coveragepy/pull/17 http://bugs.python.org/issue28260 |
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| msg277309 - (view) | Author: Antti Haapala (ztane) * | Date: 2016-09-24 07:01 | |
I am very negative to this idea. Correct code in Python **2** would either set `__hash__ = None` or redefine `__hash__` in *any* class that defines `__eq__`. That it just wasn't used like that is no excuse. This warning is even more important if even Ned Batchelder could have a bug like that in his code. It will break as soon as someone "realizes" that "hey I can use a set to remove duplicates in my container". |
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| msg277317 - (view) | Author: Christian Heimes (christian.heimes) *  |
Date: 2016-09-24 12:58 | |
Antti is correct. Please add __hash__ = None to your class to silence the warning. |
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| History | |||
|---|---|---|---|
| Date | User | Action | Args |
| 2022-04-11 14:58:37 | admin | set | github: 72450 |
| 2016-09-24 12:58:40 | christian.heimes | set | status: open -> closed nosy: + christian.heimes messages: + msg277317 resolution: not a bug stage: resolved |
| 2016-09-24 11:16:31 | nedbat | set | nosy:
+ nedbat |
| 2016-09-24 07:01:09 | ztane | set | nosy:
+ ztane messages: + msg277309 |
| 2016-09-23 23:23:01 | Roy Williams | create | |