[issue32377] Difference in ressurrection behavior with __del__ in py2 vs. py3

[Eric Cousineau]

Eric Cousineau <eric.cousineau at tri.global> added the comment:

Super late response, but for this part:

> Well... perhaps you could create another PyObject (it's just a wrapper,
> right?) since the old one doesn't have any outside references to it
> remaining.

In certain cases, yes, that would be the case. I do have unittests that
(hackily) check `id(o)` before and after resurrection by using a `weakref`,
so I could relax that contract.

However, in other cases, the "wrapper" object in Python is actually a C++
base class that has been derived from in Python. If ownership of the C++
instance (which should more-or-less own the Python portion) goes solely to C++,
then the Python portion could be garbage collected, and you get a sort-of
slicing effect:
https://github.com/pybind/pybind11/issues/1145

Granted, within this web of issues, one alternative is to always extend the
lifetime of the Python object by the C++ portion. However, that creates a
(opaque?) reference cycle between C++ and CPython, so I am a bit afraid of what
that would do. I would prefer to make memory management conservative if
possible.

Or rather: It's something cool to try out, but I have not yet had time to dig
in :(

----------

_______________________________________
Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue32377>
_______________________________________