python: what's the point of adding`dict` to `slots`

Question

The whole point of __slots__ is to save space.

But I saw people add __dict__ to it so that new attributes can be added. Isn't this defeating the goal of __slots__?

Just because you _can_ add `__dict__` to `__slots__` doesn't mean you should, or that there is any good reason to. — agf, Sep 28 '11 at 15:11
`__Slots__` and `__dict__` are different. You have got the basic concept right. This post might help you:
http://stackoverflow.com/questions/472000/python-slots Hope that helps :) — varunl, Sep 28 '11 at 15:14
`__slots__` also creates descriptors that make attribute access faster. Having `__dict__` in `__slots__` will still create a dictionary and allow dynamic attributes, but accessing them will be (very) slightly faster. (Sorry for poking an old thread, I felt like the accepted answer was insufficient) — Exa, Jul 10 '20 at 02:18

score 4 · Accepted Answer · answered Sep 28 '11 at 15:08

4

Yes. If you want __dict__, then just don't use __slots__.

answered Sep 28 '11 at 15:08

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python: what's the point of adding`__dict__` to `__slots__`