Hi Ulf
Thank you for your response.
-- QtLocation --
Thanks for catching this. See
https://codereview.qt-project.org/c/qt/qtlocation/+/500504 for a fix.
That's great, thank you.
-- 'as' operator --
This should work. Type assertions (aka "as cast") are documented in
https://doc.qt.io/qt-6/qtqml-javascript-hostenvironment.html . What
kind of object does the loader produce here? Can you please open a bug
report with a minimal example?
A bug report has been added: https://bugreports.qt.io/browse/QTBUG-116614
-- Enums in gadgets --
So, what you want to do is expose MyType as a namespace instead:
namespace MyTypeNamespace {
Q_NAMESPACE
QML_FOREIGN_NAMESPACE(MyType)
QML_NAMED_ELEMENT(MyType)
}
You cannot have reference semantics on a value type. A type with
reference semantics (aka an "object type") needs to be derived from
QObject and have a Q_OBJECT macro. The engine plays somewhat loose
with that and allows you to still access enums from such broken types.
We should amend the documentation to warn about this problem and also
generate a run time warning from the engine.
The example gadget was not the best. The gadget is used as an actual
value type in qml. A fuller example (as I have it) would be:
C++:
struct TestGadget
{
Q_GADGET
QML_ELEMENT
Q_PROPERTY(int value MEMBER value)
public:
enum class GadgetEnum
{
OptionA,
OptionB,
OptionC,
};
Q_ENUM(GadgetEnum)
public:
static void registerType();
public:
int value = 0;
};
QML: (apart from where it is used as a data type) example usage would be
// reference an instance of the gadget
... someGadgetValue.value ...
// use the enum
console.log(TestGadget.GadgetEnum.OptionB)
I've tried various permutations of the namespace macros you described,
but can't get it right. Firstly, is this possible, and if it is, what is
the canonical way of doing this? As it is it works, but you have said it
is actually a broken type.
As a side note - a Google search for "qml q_gadget enum" has these as
the top two results (at least for me) which both recommend something
along the lines of the above.
-
https://stackoverflow.com/questions/66855134/how-to-access-a-q-enum-declared-in-c-class-from-qml
- https://qml.guide/enums-in-qt-qml
I know they are not Qt documentation. Just pointing it out - it would be
nice if the Qt could somehow get a canonical example to the top of that
search.
Thanks again for the feedback
Kind regards
Matthew
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