[Development] Question about Qt's future

Tony Van Eerd tvaneerd at blackberry.com
Mon Apr 21 17:14:57 CEST 2014


> So we started to design our UI
> with QML. I liked the design to split business logic into
> C++ and UI design into QML and I still like it, but I came across
> several blocking issues (some of them are only valid for our application, some
> of them are general):
> 
> - Our application has a huge framework of value classes. They cannot (or at
> least it does not make sense to) derive from QObject for several reasons. But
> subclassing QObject is the requirement to access data from
> C++ in QML. So we had our framework of well designed value classes and
> cannot use them in QML. There were evaluations to create QObject
> wrappers, but no nice solution. So no support for value classes is probably a
> show stopper for many projects.

When I started to use QML, every 3 or 4 months I would to think "I should add Value support to QML", but never had time.
Now I think "I wish I had added Value support to QML".

You can use QVariantMaps or just send your valuetype "through" QML via a QVariant (if its members don't need to be accessed in QML, but just transferred back to C++).
Or wrap them in QObject classes.

But none of those are very nice solutions.

Modern C++ is written with value-types.  I wish Qt had more support for them.

Tony







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