On Dienstag, 19. Januar 2016 16:09:48 CET Marc Mutz wrote: > On Tuesday 19 January 2016 14:33:46 Giuseppe D'Angelo wrote: > > On Tue, Jan 19, 2016 at 3:07 PM, Marc Mutz <marc.m...@kdab.com> wrote: > > > I'd aggregate the std container instead of inheriting it, but yes, > > > that's > > > a good idea. I just wrote a mail suggesting essentially the same, only > > > slower. > > > But I'd have nothing against going all-in, either. > > > > We can't "suddenly" break CoW, though. Who's going to review the millions > > of lines of code where copies where happily taken assuming they were > > cheap? > > Who's reviewing the millions of lines of code where hidden detaches are > happily incurred even though they are not cheap? > > I'd say that if you took copies in a tight loop, you'll notice and the > profiler will find it for you. And the rest don't matter, or they will be > found by Clazy. > > I doubt many people actively use the fact that Qt containers are cheap to > copy. But yes, Qt API needs to be reviewed with an eye towards this. Then > again, Non-Qt C++ would be horribly slow if copying containers was so > prohibitly expensive.
I completely agree with Marc here. But I think him mentioning Clazy is an important point: Thanks to Clang, it is possible to write tools that automatically convert code from one version to another, taking the semantics into account. So another option is to write such a tool for Qt 6 that checks where copies are made and then notify the user about it so he can investigate it. -- Milian Wolff | milian.wo...@kdab.com | Software Engineer KDAB (Deutschland) GmbH&Co KG, a KDAB Group company Tel: +49-30-521325470 KDAB - The Qt Experts
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