[Python-Dev] reference leaks, __del__, and annotations

[Greg Ewing]

Tim Peters wrote:
> A problem is that the variant semantics also seem pretty arbitrary ;-),
> and there's a dearth of compelling use cases to guide a decision.

At the time I think I suggested that it would be
reasonable if weakref callbacks were guaranteed to
be called as long as they weren't trash themselves
and they didn't reference any trash. From what you
said in a recent message, it sounds like that's
the way it currently works.

These semantics would be sufficient to be able to
use weakrefs to register finalisers, I think. You
keep a global list of weakrefs with callbacks that
call the finalizer and then remove the weakref
from the global list.

I'll put together a prototype some time and see if
it works. I actually have a use case at the moment --
a couple of types that need to release external
resources, and since they're part of a library
I'm distributing, I can't be sure people won't put
them in cycles.

--
Greg