Re: [Interest] Overriding list properties in QML at initialisation
Ulf, I reported the bug here: https://bugreports.qt.io/browse/QTBUG-77529 I will try to propose a fix which has no side effect on Qt3D. Best regards, Unai Le mer. 14 août 2019 à 11:25, Ulf Hermann a écrit : > Hello, > > > If I create a class with a QQmlListProperty and then initialise it with > > an array in some QML file, then subclass the QML type in a second QML > > file and try to override the array there, when creating an instance of > > the child class, the list contains the arrays concatenated instead of > > the overriding array. > > That's the expected behavior of the default property, e.g. children in > QQuickItem. Arguably, it should not extend to explicitly setting any > other list properties. > > > In the following example, I would expect the list to contain 2 elements > > instead of 5. What are your thoughts? Should I fill a bug report and try > > to provide a fix? > > Yes, that would be nice. Keep in mind that the default property should > still behave the old way, but only if you actually use it as default > property. The details can be discussed in the report, though. > > best regards, > Ulf > ___ > Interest mailing list > Interest@qt-project.org > https://lists.qt-project.org/listinfo/interest > ___ Interest mailing list Interest@qt-project.org https://lists.qt-project.org/listinfo/interest
Re: [Interest] Overriding list properties in QML at initialisation
Hi Giuseppe, When you say the QML APIs for Qt3D depend on this behaviour, you are talking about appending to the default property right? Or are the APIs depending in the fact that every QQmlListProperty has its contents concatenated (I can't recall an example where this could be used)? Best regards, Unai Le mer. 14 août 2019 à 18:23, Giuseppe D'Angelo via Interest < interest@qt-project.org> a écrit : > Il 14/08/19 11:23, Ulf Hermann ha scritto: > >> In the following example, I would expect the list to contain 2 elements > >> instead of 5. What are your thoughts? Should I fill a bug report and try > >> to provide a fix? > > Yes, that would be nice. Keep in mind that the default property should > > still behave the old way, but only if you actually use it as default > > property. The details can be discussed in the report, though. > > This behaviour cannot be changed in a source-compatible way, so it's a > no-go, unless we also add additional C++/QML syntax for opting in to the > new behaviour. E.g. the QML APIs for Qt3D massively depend on this. > > My 2 c, > -- > Giuseppe D'Angelo | giuseppe.dang...@kdab.com | Senior Software Engineer > KDAB (France) S.A.S., a KDAB Group company > Tel. France +33 (0)4 90 84 08 53, http://www.kdab.com > KDAB - The Qt, C++ and OpenGL Experts > > ___ > Interest mailing list > Interest@qt-project.org > https://lists.qt-project.org/listinfo/interest > ___ Interest mailing list Interest@qt-project.org https://lists.qt-project.org/listinfo/interest
Re: [Interest] Overriding list properties in QML at initialisation
Il 14/08/19 11:23, Ulf Hermann ha scritto: In the following example, I would expect the list to contain 2 elements instead of 5. What are your thoughts? Should I fill a bug report and try to provide a fix? Yes, that would be nice. Keep in mind that the default property should still behave the old way, but only if you actually use it as default property. The details can be discussed in the report, though. This behaviour cannot be changed in a source-compatible way, so it's a no-go, unless we also add additional C++/QML syntax for opting in to the new behaviour. E.g. the QML APIs for Qt3D massively depend on this. My 2 c, -- Giuseppe D'Angelo | giuseppe.dang...@kdab.com | Senior Software Engineer KDAB (France) S.A.S., a KDAB Group company Tel. France +33 (0)4 90 84 08 53, http://www.kdab.com KDAB - The Qt, C++ and OpenGL Experts smime.p7s Description: Firma crittografica S/MIME ___ Interest mailing list Interest@qt-project.org https://lists.qt-project.org/listinfo/interest
Re: [Interest] Overriding list properties in QML at initialisation
Hello, > If I create a class with a QQmlListProperty and then initialise it with > an array in some QML file, then subclass the QML type in a second QML > file and try to override the array there, when creating an instance of > the child class, the list contains the arrays concatenated instead of > the overriding array. That's the expected behavior of the default property, e.g. children in QQuickItem. Arguably, it should not extend to explicitly setting any other list properties. > In the following example, I would expect the list to contain 2 elements > instead of 5. What are your thoughts? Should I fill a bug report and try > to provide a fix? Yes, that would be nice. Keep in mind that the default property should still behave the old way, but only if you actually use it as default property. The details can be discussed in the report, though. best regards, Ulf ___ Interest mailing list Interest@qt-project.org https://lists.qt-project.org/listinfo/interest
[Interest] Overriding list properties in QML at initialisation
Hello,
I'm using QML for some years now but recently I have found a behaviour
which may be a bug or at least makes list property initialisation
inconsistent with the way other types are handled.
The behaviour can be traced back to (at least) Qt 5.2 and is still present
in Qt 5.13.
If I create a class with a QQmlListProperty and then initialise it with an
array in some QML file, then subclass the QML type in a second QML file and
try to override the array there, when creating an instance of the child
class, the list contains the arrays concatenated instead of the overriding
array.
In the following example, I would expect the list to contain 2 elements
instead of 5. What are your thoughts? Should I fill a bug report and try to
provide a fix?
Best regards,
Unai Irigoyen
Example:
// containedtype.h //
#ifndef CONTAINEDTYPE_H
#define CONTAINEDTYPE_H
#include
class ContainedType : public QObject
{
Q_OBJECT
};
#endif // CONTAINEDTYPE_H
// mytype.h //
#ifndef MYTYPE_H
#define MYTYPE_H
#include
#include
#include "containedtype.h"
class MyType : public QObject
{
Q_OBJECT
Q_PROPERTY(QQmlListProperty myList READ myList)
QQmlListProperty myList(){
return QQmlListProperty(this, 0,
_list_append,
_list_count,
_list_at,
_list_clear);
}
private:
QList m_myList;
static inline void my_list_append(QQmlListProperty *
property,ContainedType * value)
{
MyType * instance = qobject_cast(property->object);
if(instance)
{
instance->m_myList.append(value);
}
}
static inline int my_list_count(QQmlListProperty * property)
{
MyType * instance = qobject_cast(property->object);
if(instance)
{
return instance->m_myList.count();
}
else
{
return 0;
}
}
static inline ContainedType *
my_list_at(QQmlListProperty * property, int index)
{
MyType * instance = qobject_cast(property->object);
if(instance)
{
return instance->m_myList.at(index);
}
else
{
return nullptr;
}
}
static inline void my_list_clear(QQmlListProperty * property)
{
MyType * instance = qobject_cast(property->object);
if(instance)
{
instance->m_myList.clear();
}
}
};
#endif // MYTYPE_H
// main.cpp //
#include
#include
#include "mytype.h"
int main(int argc, char *argv[])
{
QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
QGuiApplication app(argc, argv);
qmlRegisterType("array.override.test", 1, 0, "ContainedType");
qmlRegisterType("array.override.test", 1, 0, "MyType");
QQmlApplicationEngine engine;
const QUrl url(QStringLiteral("qrc:/main.qml"));
QObject::connect(, ::objectCreated,
, [url](QObject *obj, const QUrl ) {
if (!obj && url == objUrl)
QCoreApplication::exit(-1);
}, Qt::QueuedConnection);
engine.load(url);
return app.exec();
}
// BaseType.qml //
import array.override.test 1.0
MyType {
myList: [
ContainedType{},
ContainedType{},
ContainedType{}
]
}
// OverridenType.qml //
import array.override.test 1.0
BaseType {
myList: [
ContainedType{},
ContainedType{}
]
}
// main.qml //
import array.override.test 1.0
OverridenType {
}
___
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