You can use the same technique in qMakeChild as in std::make_shared - to allocate MyObjectPrivate and space for the d_ptr in one go. Probably will require some additional macroses, though, to hide the implementation (sizeof(MyObjectPrivate)) in the cpp file.
I’d say it’s an implementation detail - it *is* possible to implement the creation of QObjects more efficient than it is done now without «forcing» user to use objects on stack to avoid allocations. > 3 мая 2019 г., в 22:39, Konstantin Tokarev <annu...@yandex.ru> написал(а): > > > > 03.05.2019, 23:31, "Иван Комиссаров" <abba...@gmail.com > <mailto:abba...@gmail.com>>: >> By forcing usage of smart pointers, of course. >> The moment you start writing >> >> QWidget w1; >> QWidget w2; >> w1.setParent(QObjectSmartPointer<QWidget>(&w2)); >> >> It’s time to stop and think if you’re doing the right thing=) It is possible >> to pass an object on a stack to a unique_ptr/shared_ptr ctor, but that’s the >> problem of the person who's doing this, not the design flaw of smart >> pointers, right? >> >> We need to make it intuitive to use smart pointer and hard to use them >> incorrectly. It is quite orthogonal to «support every corner case» which are >> QObjects on stack IMHO - there are always problems with them (except for the >> top-level objects). >> >> Note, that we still need an old API for backward-compatility which works >> with QObjects on stack fine, so the user code won’t be broken in any case, >> but we might want to decide what use cases we do want to support and how >> users should write modern qt apps and what use cases are considered voodoo >> and bad practice. > > IMO it would be resonable to drop specific behavior of QObject constructor > then to force unnecessary memory allocations upon users > >> >>> 3 мая 2019 г., в 22:15, Giuseppe D'Angelo via Development >>> <development@qt-project.org> написал(а): >>> >>> Il 03/05/19 22:00, Иван Комиссаров ha scritto: >>>> Which should be considered bad practice and banned on an API level >>>> QWidget w2 >>>> QWidget w1; >>>> w1.setParent(&w2); >>>> QWidget w1; >>>> QWidget w2 >>>> w1.setParent(&w2); >>> >>> Banned at an API level -- how, exactly? >>> >>> Cheers, >>> -- >>> Giuseppe D'Angelo | giuseppe.dang...@kdab.com | Senior Software Engineer >>> KDAB (France) S.A.S., a KDAB Group company >>> Tel. France +33 (0)4 90 84 08 53, http://www.kdab.com >>> KDAB - The Qt, C++ and OpenGL Experts >>> >>> _______________________________________________ >>> Development mailing list >>> Development@qt-project.org >>> https://lists.qt-project.org/listinfo/development >> , >> >> _______________________________________________ >> Development mailing list >> Development@qt-project.org <mailto:Development@qt-project.org> >> https://lists.qt-project.org/listinfo/development >> <https://lists.qt-project.org/listinfo/development> > > > -- > Regards, > Konstantin
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