On 1 Mar 2014 01:22, "Barry Warsaw" <barry@python.org> wrote:
On Feb 28, 2014, at 10:27 PM, Nick Coghlan wrote:
With the new macro in place, the existing Py_CLEAR(x) macro would be equivalent to Py_SETREF(x, NULL).
Originally I was also concerned about the "how will people know there's
no
implicit incref?", but I've since become satisfied with the fact that the precedent set by the reference stealing SET_ITEM macros is strong enough to justify the shorter name.
I haven't had time to follow this discussion at all, but for a macro to be called Py_SETREF and *not* increment the reference counter seems at best confusing. Despite my hesitation to paint a bike shed I haven't had time to inspect, something more akin to Py_SET_POINTER seems more appropriate (i.e. don't put "REF" in the name if it isn't playing refcounting games).
It *is* playing refcounting games - it's decrefing the existing target while stealing a reference to the new target, just like the existing SET_ITEM macros and somewhat like Py_CLEAR (although in that case, it's more obvious that we will never incref NULL). The whole point of this macro is to take an *existing* reference and safely *overwrite* another existing reference, exactly as the SET_ITEM macros do. That actually gives me an idea that wasn't on Serhiy's original list: Py_SET_ATTR(target, value). After all, setting attributes safely from C is the main use case for this, and I think it strengthens the parallel with the SET_ITEM macros on the concrete types. Cheers, Nick.
-Barry _______________________________________________ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe:
https://mail.python.org/mailman/options/python-dev/ncoghlan%40gmail.com