[Python-Dev] Making weakref callbacks safe in cyclic gc

[Tim Peters]

[Neil Schemenauer]
> A hack you say?  Create a list the references itself (i.e. append
> itself).  Append all the unreachable callbacks to it and remove them
> from the weakrefs.  Put the list in the youngest generation.  The
> next gc should clean it up.

Alas, we don't know we can get enough space for a list, and if we can't
we're stuck.  Maybe Py_FatalError would be OK then, but I'd rather not.  I
think I can abuse the weakref objects themselves to hold "the list", though.
Heh.  Now *that's* a hack <wink>.