Tim Peters wrote:

For the reasons given before, that won't happen. The analysis I gave was based on a complete understanding of every gory detail of how Python's gc works -- there's simply nothing risky about this change wrt gc performance. Empirical validation is unnecessary <wink>.

If people want to surprise us, better they spend time writing nasty new tests of weakref subclassing!

Why can I forsee the strings "garbage collector" and "subclasses of weakrefs", along with "discovered in Zope3", appearing in the 2.4.1 2.4.2 and 2.4.3 release announcements? <0.5 wink> Anthony