On Mon, Jan 31, 2022 at 1:48 PM Petr Viktorin firstname.lastname@example.org wrote:
(* we could also break the stable ABI, and we could even do it reasonably safely over a long period of time, but that's a whole different discussion.)
IMO the stable ABI must be change in the long term, it still leaks too many implementation details. But right now, I didn't gather enough data about the problematic APIs and what must be changed exactly. I would prefer to only do once the work will be really blocked and there would be no other choice.
Right now, I'm focused on fixing the *API*. It doesn't require to break the stable ABI.
If we change the stable ABI, I would prefer to fix multiple issues at once. Examples:
* No longer return borrowed references (ex: PyDict_GetItem is part of the stable ABI) and no longer steal references (ex: PyModule_AddObject)
* Disallow getting direct access into an object data without a function to "release" the data. For example, PyBytes_AsString() gives a direct access into the string, but Python doesn't know when the C extension is done with it, and when it's safe to delete the object. Such API prevents to move Python objects in memory (implement a moving garbage collector in Python).
* Disallow dereferencing a PyObject* pointer: most structures must be opaque. It indirectly means that accessing directly structure members must also be disallowed. PEP 670 and PEP 674 are partially fixing the issues.