# Documentation https://docs.python.org/3/reference/datamodel.html#notes-on-using-slots One of the bulletpoints: > * Nonempty __slots__ does not work for classes derived from “variable-length” built-in types such as [int](https://docs.python.org/3/library/functions.html#int), [bytes](https://docs.python.org/3/library/stdtypes.html#bytes) and [tuple](https://docs.python.org/3/library/stdtypes.html#tuple). Points to clarify: * What does "does not work" mean? * Whats the set of "variable-length" built-in types? Is `str` one of them? <!-- gh-linked-prs --> ### Linked PRs * gh-102621 * gh-102687 * gh-102688 <!-- /gh-linked-prs -->
Documentation
https://docs.python.org/3/reference/datamodel.html#notes-on-using-slots
One of the bulletpoints:
Points to clarify:
strone of them?Linked PRs
__slots__docs. #102621__slots__docs. (GH-102621) #102687__slots__docs. (GH-102621) #102688