[Development] Allowing event delivery prior to and after QCoreApplication

[Robert Iakobashvili]

On Tue, Apr 14, 2015 at 6:27 PM, Thiago Macieira
<thiago.macieira at intel.com> wrote:
> On Tuesday 14 April 2015 16:56:19 René J.V. Bertin wrote:
> [cut]
>> ObjC is so intricately linked to OS X, because from a few quick attempts it
>> seems to be perfectly possible to use an ObjC++ wrapper class to extend the
>> retain/release scheme to C++ classes.
>>
>> Is this clear enough?
>
> Yes, thank you.
>
> C++ already has that, it's called reference counting. You may have heard we
> use it in Qt :-)
>
> The problem here is that QCoreApplication is not reference counted and we
> can't change it without breaking *every* *single* *application*, since this is
> what people usually do:
>
> int main(int argc, char **argv)
> {
>         SomeApplication app(argc, argv);
>         [rest of the application]
> }
>
> That stack declaration is the problem here. The app object will be destroyed
> at the closing brace, whether we want it or not, and there's nothing we can do
> to prevent it, delay it or even hook something as it begins.
>
> We can only catch it half-way through, when the destruction has reached one of
> our classes (~QApplication, ~QGuiApplication or ~QCoreApplication), by which
> time the virtual table has already changed and it's too late.

C++ idiom with protected destructor
enforces heap-allocation of objects and prevents stack allocation.
It requires some public destroy() calling "delete this" inside.

jm2c

Regards,
Robert