[Development] Go's "defer" statement for C++/Qt

Julien Cugnière julien.cugniere at gmail.com
Thu Mar 7 18:16:45 CET 2019


Le jeu. 7 mars 2019 à 18:09, Tor Arne Vestbø <Tor.arne.Vestbo at qt.io> a écrit :
>
> https://doc.qt.io/qt-5/qscopeguard.html
>

Nice !

And apparently there is also
https://doc.qt.io/qt-5/qscopedvaluerollback.html, which seems to be a
public and templatized version of QBoolBlocker.

> Tor Arne
>
> > On 7 Mar 2019, at 18:01, Volker Hilsheimer <volker.hilsheimer at qt.io> wrote:
> >
> > Ahoy,
> >
> > In what little development I’ve done in golang, I appreciated the “defer” statement as a means to write cleaner code. Basically, defer schedules a statement for execution when the stack unwinds.
> >
> > https://tour.golang.org/flowcontrol/12
> >
> > We have several specialized helper classes in Qt for similar purposes, f.ex QMutexLocker and friends, or the internal QBoolBlocker [1]. Seeing the various specialized classes we have, I thought that something generic in Qt could be useful to have (although our specialised classes provide some additional convenience and/or logic).
> >
> > So, I pushed a few lines code to
> >
> > https://git.qt.io/vohilshe/qt_defer
> >
> > Would like to hear what you think.
> >
> > Perhaps someone can find ways to make this more elegant without introducing tons of preprocessor/macro shenanigans, or perhaps even without depending on C++17's implicit template argument deduction (without enabling C++17 in the config this doesn't build for me, even though I don’t use auto in the template paramter list).
> >
> >
> > Cheers,
> > Volker
> >
> >
> > [1] which was requested to be made public in https://bugreports.qt.io/browse/QTBUG-38575


Julien Cugnière


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