On 16/12/20 08:53, Marc-André Lureau wrote:
On the principle, I fully agree. But the risk is high to introduce
regression if objects are manipulated in strange ways.
I remember I wanted object_unref() to automatically remove itself from
the parent when the last ref is dropped. I think there were similar
concerns.
unref and unparent are two very different operations; the former means
*I* am done with this object, the latter means *QEMU* is done with this
object (even though there may be a few reference held, e.g. on the call
stack or by RCU). Since object_unparent operates on global state, you
can even call object_unparent if you don't own yourself a reference to
the object and just got the pointer from the caller.
While unref is a "mechanical" operation of dropping a reference and
possibly freeing the object, unparent is an active operation that
includes for example dropping reference cycles or in general detaching
from other places that are known to hold references to this object.
This is not a concept that is specific to QEMU, I think I read somewhere
that LibreOffice's UI library does something similar, calling it "dispose".
Paolo
