[Python-Dev] Counting references to Py_None
tim.peters at gmail.com
Mon Mar 21 17:56:06 EDT 2016
Brett Cannon <brett at python.org>]
>> And if we didn't keep its count accurately it would eventually hit
>> zero and constantly have its dealloc function checked for.
[> I think the idea is really consistency. If we wanted to avoid all
> "Py_INCREF(Py_None);", it would be possible: we could let the refcount
> of None decrement to zero, at which point its deallocator is called;
> but this deallocator can simply bumps the refcount to a large value
> again. The deallocator would end up being called very rarely.
It could, but it does something else now ;-) I've seen this trigger,
from C code that had no idea it was playing with None, but just had
general refcounting errors. So this does serve a debugging purpose,
/* This should never get called, but we also don't want to SEGV if
* we accidentally decref None out of existence.
(that's in object.c)
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