[Development] QML Language Development from Qt CS

[Alan Alpert]

Going forwards the QML language is not fixed, and once the mighty V4
switch takes place it should be easier than ever to improve! The
decision was that the QML language version is linked to the Qt Version
(C++ lib QtQml version), and follows the same compatibility rules. So
we can't break plugin compatibity again until Qt 6. QML applications
will need to depend on a minimum version of Qt (or qml runtime), same
as C++ applications.

Short term plans including adding the 'pragma' keyword, and a 'pragma
singleton' directive. The pragma keyword will be valid only in the
preamble, and the singleton directive will mark that file as a
composite singleton type. It will behave the same way as a C++
QJSValue/QObject singleton type does currently. I'll try to find
someone in Blackberry to help me implement this.

Longer term plans involve adding enums, const properties and group
properties, rough syntax described but not finalized
http://qt-project.org/groups/qt-contributors-summit-2013/wiki/Evolution-of-the-QML-language
. There is no ETA on those changes, so if you're really keen on seeing
them I'm happy to review patches.

Also covered was that QtQml is the 90% replacement for QtScript. QtQml
with QJSValue and QJSEngine, not just QQmlEngine, is what will be
provided for application scripting (even non-GUI scripting) going
forwards. So keep in mind that its mandate covers more than just
QtQuick and GUI declarations.

--
Alan Alpert