Hi,
QMetaProperty::isEnumType's documentation probably should be adjusted to
mention that it really is about having an enum marked with Q_ENUM, not
about generic C++ enums.
For your use-case: I suspect you need to create a dynamic meta-type for
your enum (or rather, the QtPrivate::QMetaTypeInterface), and pass that
to `QMetaEnumBuilder::setMetaType`. You can probably get away by copying
most information from the QMetaTypeInterface of the underlying type, and
just adjusting name and setting the flags.
I suspect we don't have this kind of code in Qt, becuse QML currently
doesn't allow QML defined enum properites, which would be the place
where it's needed.
Kind regards,
Fabian Kosmale
On 04.10.24 14:43, Phil Thompson wrote:
Hi Fabian,
The change was https://codereview.qt-project.org/c/qt/qtbase/+/559265
Reverting this change means I get the same behaviour as I get with v6.7.
I am (and always have been) using QMetaObjectBuilder and addEnumerator()
(the overload that takes a QByteArray argument).
I've compared the following scenarios...
a moc-generated meta-object where Q_ENUM is not used
a moc-generated meta-object where Q_ENUM is used
a dynamically created meta-object.
...for v6.7.1, v6.8.0 and v6.8.0 with the change reverted. In each case
I looked at the results of...
QMetaEnum.metaType().isValid()
QMetaProperty.metaType().isValid()
QMetaProperty.isEnumType()
The results in all cases for v6.7.1 and v6.8.0 with the change reverted
were identical.
For moc-generated meta-objects...
- the results were consistent across all versions of Qt
- QMetaProperty.metaType().isValid() always returned true (even if
QMetaEnum.metaType().isValid() returned false)
- QMetaProperty.isEnumType() returned true if Q_ENUM was used and false
if it wasn't
For dynamically created meta-objects...
- the results were dependent on the version of Qt
- QMetaProperty.metaType().isValid() always returned false
- QMetaProperty.isEnumType() returned true for v6.7.1 and false for v6.8.0
I was surprised by the result of QMetaProperty.isEnumType() for a
moc-generated meta-object without Q_ENUM. The docs suggest this should
be true for all enums whether or not Q_ENUM is used.
This actually means that the v6.8 dynamic behaviour is closer to the
moc-generated behaviour but means it seems to be impossible to
dynamically create an enum property where QMetaProperty.isEnumType()
returns true.
Some questions...
Why does QMetaProperty.metaType().isValid() always return true for
moc-generated meta-objects and false for dynamically created meta-objects?
Is there any way to dynamically register an enum with the meta-type
system (so that QMetaEnum.metaType().isValid() returns true)?
Regards,
Phil
On 04/10/2024 08:02, Fabian Kosmale via Development wrote:
Hi Phil,
I'm not quite sure which change caused the issue, and I believe a
bugreport with a reproducer might shed some light on the issue.
Nevertheless, if you're already using the private QMetaObjectBuilder
API, I would expect that it should work if you build the enum also
dynamically via addEnumerator and then working with the returned
QMetaEnumBuilder.
Kind regards,
Fabian
On 03.10.24 17:52, Phil Thompson via Development wrote:
On 03/10/2024 16:31, Volker Hilsheimer wrote:
On 3 Oct 2024, at 17:07, Phil Thompson via Development
<development@qt-project.org> wrote:
On 03/10/2024 15:44, Thiago Macieira wrote:
On Thursday 3 October 2024 05:06:08 GMT-7 Phil Thompson via
Development wrote:
Yes, that's the change - commenting out the new test fixes the
problem.
I am dynamically building the meta-object. You don't really build an
enum, you just provide a description of it to the meta-object. It
would
be nice to be able to register an enum with the meta-type system
dynamically.
Or you can set the EnumOrFlag flag in the QMetaProperty flags
field to
force the
constructor to search.
Sorry, can you be more specific? I can't see how to do it given the
private nature of the flags.
Phil
Hey Phil,
How do you generate a dynamic meta object without using private APIs?
Do you use QMetaObjectBuilder (which is private), or do you generate
the tables and arrays by hand?
If you use QMetaObjectBuilder, then
QMetaPropertyBuilder::setEnumOrFlag would be the way to go.
Volker
I'm using QMetaObjectBuilder and already calling setEnumOrFlag, so
that doesn't seem to solve the problem.
An alternative that would work for me would be to bypass the new test
if the meta-type was invalid (ie. the enum wasn't registered) but I
don't know if that would nullify the purpose of the new test.
Phil
--
Fabian Kosmale
Manager R&D
The Qt Company GmbH
Erich-Thilo-Str. 10
D-12489 Berlin
fabian.kosm...@qt.io
+49 1638686070
--
Fabian Kosmale
Manager R&D
The Qt Company GmbH
Erich-Thilo-Str. 10
D-12489 Berlin
fabian.kosm...@qt.io
+49 1638686070
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