[Python-Dev] PyWeakref_GetObject() borrows its reference from... whom?

[Guido van Rossum]

On Mon, Oct 10, 2016 at 1:57 PM, Larry Hastings <larry at hastings.org> wrote:
>
> On 10/10/2016 06:37 PM, Guido van Rossum wrote:
>
> Modified +1: you can't change the behavior of the existing API, but
> you can deprecate it and introduce a better one with a different name.
> We'll have until Python 4.0 to carry through the deprecation anyways.
> And I doubt this is the only C API change needed for happy gil-free
> coding...
>
>
> First, "deprecate" won't work for these semantics for the Gilectomy branch.
> I simply cannot safely support the semantics of the existing function.  All
> call sites need to change.

Oh, in the gilectomy you can fix all call sites. Even in CPython. But
3rd party extensions should not have this API removed in Python 3.7.

> Second, consider that every function that returns a borrowed
> reference--PyDict_GetItem(), PyList_GetItem()--has to change too, to return
> an actual (non-borrowed) reference.  It's going to be a major upheaval in
> the C API.

Yeah, this has been discussed to death in the rest of the thread.

> For now I'm going to leave the names as-is and just change the semantics
> everywhere.  If this approach really works, and if we decide we want to
> merge it back into trunk--and those are both still big if's--we can revisit
> this decision.

Changing something as subtle as this to an API sounds really bad even
in an experimental branch. But it's your branch and you can do what
you want (then again, why did you bring it up here? :-).

> I haven't yet ruled out abandoning reference counting completely and going
> to 100% tracing garbage collecting,

I guess that would have its own set of pros and cons.

-- 
--Guido van Rossum (python.org/~guido)