[Python-Dev] Experimental features and __slots__

[Martin v. Loewis]

Recently, there has been a concern that if __slots__ is added to the
language, we'll be stuck with it forever. I want to propose a strategy
that doesn't require things to be cast in stone right now.

PEP 5 should be enhanced to allow the notion of experimental
features. Programs using experimental features should expect to break
from one release to another, with no need to deprecate the
experimental feature. If desired, __future__ import could be required
to activate experimental features, with a prospect that they disappear
in the next release. However, this is not strictly necessary:
Documenting experimental features may be sufficient.

For 2.2, I propose that all __ attributes relating to new-style
classes are experimental.

Regards,
Martin