Details
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Bug
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Resolution: Unresolved
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P3: Somewhat important
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6.3.0
Description
A Q_PROPERTY() without being BINDABLE can be initialized with a binding from QML. But one that is BINDABLE cannot, it simply remains uninitialized. Below is a simple test that I did with int and QObject* as the property types...
C++ class with properties. There are four total, two of each type where one is BINDABLE and the other isn't:
#ifndef MYTYPE_HPP #define MYTYPE_HPP #include <QBindable> #include <QDebug> #include <QObject> class MyType : public QObject { Q_OBJECT Q_DISABLE_COPY(MyType) Q_PROPERTY(int debug1 READ getDebug1 WRITE setDebug1 NOTIFY debug1Changed) Q_PROPERTY(int debug2 READ getDebug2 WRITE setDebug2 NOTIFY debug2Changed BINDABLE bindableDebug2) Q_PROPERTY(QObject* debug3 READ getDebug3 WRITE setDebug3 NOTIFY debug3Changed) Q_PROPERTY(QObject* debug4 READ getDebug4 WRITE setDebug4 NOTIFY debug4Changed BINDABLE bindableDebug4) signals: void debug1Changed() const; void debug2Changed() const; void debug3Changed() const; void debug4Changed() const; public: QBindable<int> bindableDebug2() const { return QBindable<int> (&_debug2); } QBindable<QObject*> bindableDebug4() const { return QBindable<QObject *>(&_debug4); } int getDebug1() const { qDebug() << "Get debug1" << _debug1; return _debug1; } int getDebug2() const { qDebug() << "Get debug2" << _debug2; return _debug2; } QObject* getDebug3() const { qDebug() << "Get debug3" << _debug3; return _debug3; } QObject* getDebug4() const { qDebug() << "Get debug4" << _debug4; return _debug4; } void setDebug1(int debug1) { qDebug() << "Set debug1" << _debug1 << "->" << debug1; if (debug1 != _debug1) { _debug1 = debug1; emit debug1Changed(); } } void setDebug2(int debug2) { qDebug() << "Set debug2" << _debug2 << "->" << debug2; if (debug2 != _debug2) { _debug2 = debug2; emit debug2Changed(); } } void setDebug3(QObject* debug3) { qDebug() << "Set debug3" << _debug3 << "->" << (void*)debug3; if (debug3 != _debug3) { _debug3 = debug3; emit debug3Changed(); } } void setDebug4(QObject* debug4) { qDebug() << "Set debug4" << _debug4 << "->" << (void*)debug4; if (debug4 != _debug4) { _debug4 = debug4; emit debug4Changed(); } } private: int _debug1{0}; Q_OBJECT_BINDABLE_PROPERTY_WITH_ARGS(MyType, int, _debug2, 0, &MyType::debug2Changed) QObject* _debug3{nullptr}; Q_OBJECT_BINDABLE_PROPERTY_WITH_ARGS(MyType, QObject*, _debug4, nullptr, &MyType::debug4Changed) public: explicit MyType(QObject *parent = nullptr) : QObject{parent} {}; }; #endif // MYTYPE_HPP
Creating an instance of MyType and attempt to assign a binding to each. Once initialization is over, log the value for each of them.
Unable to find source-code formatter for language: qml. Available languages are: actionscript, ada, applescript, bash, c, c#, c++, cpp, css, erlang, go, groovy, haskell, html, java, javascript, js, json, lua, none, nyan, objc, perl, php, python, r, rainbow, ruby, scala, sh, sql, swift, visualbasic, xml, yaml
MyType {
debug1: { console.log(`Binding for debug1 = ${10}`); return 10; }
debug2: { console.log(`Binding for debug2 = ${10}`); return 10; }
debug3: { console.log(`Binding for debug3 = ${this}`); return this; }
debug4: { console.log(`Binding for debug4 = ${this}`); return this; }
Component.onCompleted: {
console.log(`Starting value for debug1 = ${debug1}`);
console.log(`Starting value for debug2 = ${debug2}`);
console.log(`Starting value for debug3 = ${debug3}`);
console.log(`Starting value for debug4 = ${debug4}`);
}
}
This is the output. Only debug1 and debug3 were set by their binding. The bindings for debug2 and debug4 weren't even attempted.
qml: Binding for debug1 = 10 Set debug1 0 -> 10 qml: Binding for debug3 = MyType(0x563e0aa24d60) Set debug3 0x0 -> 0x563e0aa24d60 Get debug1 10 qml: Starting value for debug1 = 10 Get debug2 0 qml: Starting value for debug2 = 0 Get debug3 MyType(0x563e0aa24d60) qml: Starting value for debug3 = MyType(0x563e0aa24d60) Get debug4 0x0 qml: Starting value for debug4 = null