I was looking at a problem regarding deferred deletes causing a crash inside
nested loops and it was pointed out that in
QCoreApplication::setPostedEvents() there is some code there that
determines whether it is safe to delete the object or not. From my
understanding it will only delete an object if the loop level that it was
called from is greater than the current one. However it seems that if the
loop level is 0 (i.e. main event loop I guess) and the current one is
higher than 0 it deletes anyway, is this the correct intention? Does anyone
know why this is safe if so?
For reference the code is this bit specifically:
const bool allowDeferredDelete =
(loopLevel data-loopLevel
|| (!loopLevel data-loopLevel 0)
|| (event_type == QEvent::DeferredDelete
loopLevel == data-loopLevel));
Where loopLevel is 0 but data-loopLevel is greater than 0.
Loop level equal to 0 means the object was deleteLater'ed in main(), before
exec(). That is, when no event loop was started. That means any event loop
level can delete it.
Otherwise, the object is only deleted if you're running a loop with equal or
*lower* nesting level than when it was deleteLater'ed.
Aha, this does make a lot of sense, thanks this is very useful to know :)
Andy
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