[Development] QAction-like API for QML

Stephen Kelly stephen.kelly at kdab.com
Wed Dec 12 18:36:28 CET 2012

On Tuesday, December 11, 2012 23:57:48 you wrote:
> On Tue, Dec 11, 2012 at 09:48:22AM -0800, Alan Alpert wrote:
> > > We also need to find out whether we can come up with something which
> > > QtWidgets users can migrate to (the QWidget* in the QAction API is
> > > quite niche, and not necessarily ideal API anyway). Possibly even
> > > investigating whether QAction can be implemented in terms of a new
> > > QGuiAction (?) API should be done. This can't be QML-only. There
> > > needs to be C++ backing too.
> > 
> > Why can't this be QML-only? For the set of controls exposed in
> > C++-only we have a C++-only Action API. When we add a set of controls
> > exposed in QML-only we can have a QML-only Action API. We don't
> > currently have a C++ UI something which QtWidget users can migrate to,
> > we'd need to consider that first before trying to make this new API
> > fit in with whatever that would be.
> The missing _easy_ accessibility from C++ is _the_ pain point of the
> whole QML story right now from a "medium sized application" point of
> view. It would be really nice to get rid of that divide, not to pile
> up more code that's not addressing both sides.


> > I agree there should be a migration path for existing QAction users,
> > and that we should support hybrid applications.
> Right. And not as after-thought, but as first class citizen.

Yes, yes, yes!

> > But there are other ways to support those use cases than adding a
> > C++ API for the new Actions. My initial thought is something like a
> > QActionBridge which can take a QAction or a QML Action to start with
> > and then generates the other on the fly. It's not pretty, but it's a
> > lot easier than abstracting out a QGuiAction and still allows you to
> > get a reference to the other type if you need the interoperability.
> That's already an implementation detail. It does indeed not have to be
> the same object, and it does not have to have _exactly_ the same
> interface. But it has to be "highlevel", and one has to be able to
> easily shift stance, i.e. move things from one side of the divide to
> the other without much ado. 


> This sort of implies that the interfaces,
> down to property names, should be as close as possible - even if the
> "using" languages are quite different.


Stephen Kelly <stephen.kelly at kdab.com> | Software Engineer
KDAB (Deutschland) GmbH & Co.KG, a KDAB Group Company
www.kdab.com || Germany +49-30-521325470 || Sweden (HQ) +46-563-540090
KDAB - Qt Experts - Platform-Independent Software Solutions
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