__slots__ purpose

Question

__slots__ purpose

Accepted Answer

By default, every Python instance has a __dict__ that can hold arbitrary attributes - flexible but memory-heavy. __slots__ = ('x', 'y') removes __dict__ and stores those two attributes in fixed-offset slots instead. Benefits: lower memory per instance (important when creating millions of objects), slightly faster attribute access. Tradeoff: you cannot add new attributes dynamically. Used heavily in data-intensive code like geometry libraries, ORMs, and simulation engines.