The Future of QML

TALK: The Future of QML
SPEAKER: Ulf Hermann
COMPANY: The Qt Company
TRACK: Qt & Technical Deep Dive
Talk recorded at the Qt World Summit 2019 event in Berlin.
#QtWS19 November 2019 - BCC
TALK DESCRIPTION:
On the way to Qt 6 the QML language and engine face major new challenges and developments. In order to scale down to smaller and smaller devices, the QML language needs to be decoupled from JavaScript and it needs to be compiled ahead of time, with as little run-time loading as possible. In order to address this, a new major version of the language is being drafted. As a result of the changes much of what is currently part of the core QML library - the JavaScript engine including its garbage collector, dynamic compilation of QML, the QML metatype system - will be moved into different modules and/or becomes optional. For simple binding expressions you don’t need a full JavaScript engine, and you shouldn’t have to pay for one. The talk will give an overview of the new architecture as well as the changes to the language. In particular, it will show how bindings can become more lightweight and as public API in Qt Core. It will also show what changes you will need to apply to your QML files in order to actually avoid the usage of JavaScript and to compile them ahead of time.
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[@Alex-kr7zr]

Is there any update on this talk? How much has really been implemented and what is deprecated? I can't really find good documentation.

[@TheBootroo]

I'm okay with 99% of this, but for God sake, why replacing grouped properties (thus, readonly object property) with writable object properties all the way ? it's not the same cost at all, and that's the only change I'm worried it may degrade perfs, while all the others will improve them... Please reconsider.

[@TheBootroo]

To declare a proper grouped property you must use "readonly property alias inner: id_of_inner_object" and your issue with "delayed" is fixed, and in addition you cannot replace it anymore with another instance. And your bug with the additional property declared in inner object and not accessible outside is not a bug, you are declaring Rectangle typed property but you put an implicit Rectangle subclass and expect ducktyping to do the work for you ? just explicitely declare your Rectangle subclass and use it as property type.

[@davinelLinvega]

About encapsulation, have you thought about adding a strict mode to QML where no property outside of a .qml file could be accessed? This would enforce proper APIs on the .qmls root object and avoid many of the problems adressed here. So I couldnt just access any id, property or parent in my lookup hierarchy

[@hatema]

I've been using QML a lot and it's really promising! Can't wait for QML 3.