Skip to content

Latest commit

 

History

History
138 lines (106 loc) · 3.16 KB

language.md

File metadata and controls

138 lines (106 loc) · 3.16 KB
Raw

Supported QML/JS syntax

qmluic supports a tiny subset of QML and JavaScript/TypeScript syntax. The language is syntactically compatible with QML/JS so you can use Qt Creator for editing, but the semantics is diverged from JavaScript.

Notable differences are:

  • No implicit type conversion (except for object upcasting on assignment.)
  • Integer and floating point are distinct types.
  • Integer division returns an integer.

Bindings

Constant expression will be embed in the .ui XML file.

windowTitle: qsTr("Hello world!")

If the right-hand expression isn't constant, it will be automatically re-evaluated when the underlying value changes.

QComboBox { id: edit }
QStackedWidget { id: stack; currentIndex: edit.currentIndex }

Under the hood, this will be translated to the following signal/slot connection.

connect(edit, &QComboBox::currentIndexChanged, root,
        []() { stack->setCurrentIndex(edit->currentIndex()); });

Callbacks

Signal callback can be attached by on<Signal>.

QDialogButtonBox {
    onAccepted: root.accept()
    onRejected: root.reject()
}

In order to take signal arguments, wrap the callback statements with function() { ... }. Unlike QtQuick/QML, type annotation is mandatory.

onToggled: function(checked: bool) {
}

Attached properties

TODO: metatype_tweak.rs

Types

In addition to Q_OBJECT/Q_GADGET classes and Q_ENUMs, the following types are defined.

  • bool
  • double / qreal
  • int
  • uint
  • QBrush
  • QColor
  • QCursor
  • QIcon
  • QPalette
  • QString
  • QStringList (aliased to a list of QString)
  • QVariant
  • void

Not all types are usable in dynamic expression context. For example, there's no QColor constructor yet.

QObject-derived objects are passed by pointer.

Operators

  • Unary arithmetic: +, -
  • Unary bitwise: ~
  • Unary logical: !
  • Binary arithmetic: +, -, *, /, %
  • Binary bitwise: &, ^, |
  • Shift: >>, <<
  • Binary logical: &&, ||
  • Comparison: ==, !=, <, <=, >, >=
  • List subscript: <list>[<index>] (no bounds check)
  • Type cast: <value> as <type>
    • numeric cast amongst int / uint / double
    • enum to integer
    • bool to integer
    • discarding result: <value> as void
    • extract stored value from QVariant
    • TODO: qobject_cast for downcasting will be added later
  • Ternary: ... ? ... : ...

Operands are statically type checked. <string> + <int> is invalid for example.

Strict comparison operators, === and !==, are aliased to == and != respectively. There are no lax comparison operators.

Builtin functions and methods

Functions:

  • Math.max(a, b), Math.min(a, b)
  • console.log(), .debug(), .info(), .warn(), .error()
  • qsTr()

Methods:

  • QList<T>::isEmpty()
  • QString::arg()
  • QString::isEmpty()

Statements

  • let / const (type annotation or initial value is required)
  • if / else
  • switch / case / default / break (case expression is tested by == operator)
  • return

No loop statement is available.