On 2017-04-25 23:04, Thiago Macieira wrote:
On Tuesday, 25 April 2017 17:49:16 -03 Alejandro Exojo wrote:
On Tuesday 25 April 2017 16:35:01 Thiago Macieira wrote:
> QVector and QList don't have the same API. They're slightly different.
> What'sm ore, QList has a beginning-of-list optimisation, whereas QVector
> doesn't (not even my copy, I stopped development shortly before I got to
> that part, even if I did add a QArrayData::GrowsBackward flag to support
> the case).
>
> (...)
>
> So, no, we can't implement that in Qt 5. In Qt 6, we've already agreed we
> don't want this mess, so QList as it is simply goes away.
By the way, which is the exit strategy for QQueue?
Do we need one?
The only reason that QQueue uses QList is because QList has that
takeFirst()
optimisation, while QVector does not. Once we implement that for
QVector, we
should be able to use QQueue with QVector too.
FWIW: I'm against adding even more pessimising goodies to QVector. An
area for push_front is such a goodie. The addition this causes is
probably the reason why a QList, even for optimal payloads, is
outperformed by QVector in my well-known benchmark from -Wmarc. Users
that need a queue can use std::deque. If you don't iterate over it, it's
a more than acceptable container.
Thanks,
Marc
_______________________________________________
Development mailing list
[email protected]
http://lists.qt-project.org/mailman/listinfo/development
