Steven D'Aprano <steve+comp.lang.pyt...@pearwood.info> wrote: > You can create instances without a __dict__ by setting __slots__:
That is a necessary but not a sufficient condition. An instance of a class can be created without a dict only if (either you set __slots__ or you implement it in C without a __dict__ attribute) AND none of its base classes require a dict. Setting __slots__ when a base class requires that its instances have a __dict__ doesn't prevent creation of the __dict__. > > But the class itself still has a __dict__: The class is an instance of 'type'. Instances of 'type' require a dict therefore every class requires a dict. Except of course for old style classes in Python 2.x but they have a __dict__ too. Also you cannot create a subclass of 'type' with non-empty slots (it throws a type error "nonempty __slots__ not supported for subtype of 'type'"). However I don't think that's really relevant as even if they did allow you to use __slots__ it wouldn't prevent the creation of a __dict__ for the 'type' base class. > I don't have a use-case for this. But I have some code which assumes > that every class will have a __dict__, and I wonder whether that is a > safe assumption. I believe so. -- Duncan Booth http://kupuguy.blogspot.com -- http://mail.python.org/mailman/listinfo/python-list
