__slots__ in python

It involves the usage of __slots__ to tell Python not to use a dict, and only allocate space for a fixed set of attributes.

From Python documentation: __slots__ allows us to explicitly declare data members (like properties) and deny the creation of __dict__ and __weakref__ (unless explicitly declared in __slots__ or available in a parent.).

You see that every “thing” in Python has a __dict__ attribute, even a class itself.