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

Nick Coghlan ncoghlan at gmail.com
Tue Oct 11 00:33:03 EDT 2016

On 11 October 2016 at 08:49, Guido van Rossum <guido at python.org> wrote:

On Mon, Oct 10, 2016 at 1:57 PM, Larry Hastings <larry at hastings.org> wrote:

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'm guessing Larry was hoping someone else would see a possible solution that he'd missed.

On that front, while I don't see an alternative to making borrowed references real references in a GIL-free Python, I do think we may need to keep the borrowed/new distinction for the sake of folks writing cross-version compatible code. To explain why, consider these scenarios:

Assuming that the GILectomy does end up needing to implicitly treat all borrowed references as new references, that suggests we're going to need APIs like "PyBorrowed_DECREF" to provide the "only decref when built without the GIL" semantics, and the rules for GIL-independent source code would become:

Regards, Nick.

-- Nick Coghlan | ncoghlan at gmail.com | Brisbane, Australia

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