[Development] QMetaType support for QFuture

[Arno Rehn]

Am 10.05.2021 um 10:04 schrieb Fabian Kosmale:
> Regarding the API: I think the most common pattern in Qt would be to
> add a static get method to the private class.
> 
> @Arno: But would that accessor actually be enough for you? As in, do
> you know in your case that the QVariant contains a QFuture? If you
> get a generic QVariant instead, you may still need a way to detect
> that the contained type is in fact a QFuture (though QMetaType::name
> might be enough in that case).

Yep, I was thinking of just checking QMetaType::name().
Still, getting this right without relying on UB will be more work than I 
expected.
Suppose the QVariant contains a QFuture<int>. How would I generically 
extract the QFuture<T> to then call QFuturePrivate::get() on it?
One way to possibly be to convert this unconditionally to a 
QFuture<void>, but then QVariant needs to generically know about QFuture 
conversion operators/constructors. All doable, but this is going to be 
my first "deep dive" into QtCore internals :-)

Regards,
Arno

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Arno Rehn
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