KDE 5, Qt 5 and QML - What is advised for writing new (KDE) applications in the long term?

[Mark]

On Fri, Aug 12, 2011 at 5:11 PM, Shaun Reich <shaun.reich at kdemail.net> wrote:
> On Fri, Aug 12, 2011 at 10:22 AM, Mark <markg85 at gmail.com> wrote:
>> 1. Write the application in Qt mostly and use kdelibs where needed?
>> 2. Same as 1. but make the GUI in QML like i did in the example above?
>> 3. Skip C++ altogether and make in in QML only?
>> .. more options?
>>
>> I personally like option 2 the best since i get everything i want and
>> i just dislike making an entire desktop application in JavaScript
>> whatever the performance is.
>>
>> But what is the goal (or desire) for KDE with the plasma desktop and
>> all KDE apps?
>
> For Plasma, and plasma-desktop, the answer is "qml as much as is
> possible" which in this case tends to be just about everything.
>
>>Full QML all the way? or like option 2?
>> I know Dragon is going to use the phonon QML and some more QML elements.
>
> Dragon's use case is a bit simple if you think about it. You need to
> display a video on the entire scene, and then just have a small popup
> panel that is used for e.g. seeking, pausing the video. (you can see
> that in the pko screenshot for instance).
>
>
> Well for starters, #3 is out of the question. You need *some* C++ to
> actually expose the data and perform actions and such. QML should just
> be seen as the UI, that's all it is. Especially since data retrieval
> and the corresponding actions in general, have a lot to do
> performance-wise.
>
> #2 is fine for this particular case, since it isn't really doing a
> whole lot of complex actions.
>
> I don't know how practical making "entire desktop application[s]" in
> QML is. I'd say it's good for "light" things, but full-blown resource
> intensive applications I would not use it for. Ones that require
> complex layouts/UI features, and heavy model usage (I've found the
> view classes to be sort of limited). Your example was rather simple,
> and that tends to be the scope of Plasma Applets, which is why it
> makes it easy for them.
>
> Of course, qt quick desktop components isn't even out yet.
>
> My .5 cents.
>
> --
> Shaun Reich,
> KDE Software Developer (kde.org)
>

So, as a rule of thumb the best thing is to make new applications in
C++ with QML for the GUI?