[Tutor] __slots__

[Kent Johnson]

Liam Clarke wrote:
> Well, all I can say is, don't use them unless you need them, they're a
> lot of hassle.

I think the conventional advice is something like, if you don't understand why using slots is a bad idea, you have no business using them :-)

> I created two versions of the same object, same attribute values,  one
> with slots, one without.
> 
> With slots, it pickled to a string of 163 characters. Without,
> 341.That's 178 bytes saved, rough approximation. So, if I create 5000
> objects, I've saved somewhere around 900Kb of RAM.

Does the size of the pickle correlate to the size of the runtime object? I don't know...

Kent

> 
> At 500,000 objects I'd be saving roughly 86Mb of RAM, assuming that a
> pickled object corresponds to one in memory. Or, 86Mb of HD space.
> 
> Of course, having to learn what __getstate__ was in order to pickle
> the slotted instance wasn't much fun. Remember, premature optimisation
> is bad...
> 
> This was a smaller object, so it'll be interesting to see what economy
> an object with 70ish attributes makes. FWIW, I'm doing the exact
> opposite of XP, and building to handle 300,000 to 600,000 objects...
> 
> Regards,
> 
> Liam Clarke
> _______________________________________________
> Tutor maillist  -  Tutor at python.org
> http://mail.python.org/mailman/listinfo/tutor
> 
>