Jacob Hallen wrote: > Patrick Maupin <[EMAIL PROTECTED]> wrote: > >Also, as I noted, I _do_ use them on occasion, so if there really _are_ > >potential pitfalls there, I would like to understand exactly what they > >are, so my ears perk up whenever I notice a __slots__ discussion, but > >so far I have been repeatedly disappointed, in that I always see > >someone saying "don't do that" but I have never seen a cogent technical > >argument about how my scripts which __slots__ are going to suddenly, > >irretrievably break one day. > > The proper use of__slots__is to save space in objects. Instead of having > a dynamic dict that allows adding attributes to objects at anytime, > there is a static structure which does not allow additions after creation. > This saves the overheadof one dict for every object that uses slots. > While this is sometimes a useful optimisation, it would be completely > unnecessary if the Python interpreter was dynamic enough so that it would > only require the dict when there actually were additions to the object. > > Unfortunately there is a side effect to slots. They change the behaviour of > the objects that have slots in a way that can be abused by control freaks > and static typing weenies. This is bad, because the contol freaks should > be abusing the metaclasses and the static typing weenies should be abusing > decorators, since in Python,there should be only one obvious way of doing > something. > > Making CPython smart enough to handle saving space without __slots__ is a a > major > undertaking, which is probably why it is not on the list of changes for P3k > (yet). > > Jacob Hallén
Thanks, Jacob! Saving space is exactly why I use __slots__, so I can sleep better now :) Regards, Pat -- http://mail.python.org/mailman/listinfo/python-list
