invoking QObject operators from JS/QML

[mzimmers]

Hi all -

I'm trying to invoke the (in)equality operator of a QObject-derived class from QML, but, according to the debugger, I never hit the operator.

class Equipment : public QObject
{
    Q_OBJECT
    QML_ELEMENT
public:
    explicit Equipment(QObject *parent = nullptr);
    virtual bool operator == (const Equipment &rhs) const;
    virtual bool operator != (const Equipment &rhs) const { return !operator==(rhs); };
    
// qml
ColumnLayout {
    property Equipment equipmentCopy
    property Equipment equipmentOriginal: equipmentModel.getEquipment(equipmentCopy.uuid)
    Button {
        onClicked: {
            if (equipmentCopy !== equipmentModel.getEquipment(equipmentCopy.uuid)) {
            ...

Is this not possible, or am I just doing something wrong?

Thanks...

[kshegunov]

@mzimmers said in invoking QObject operators from JS/QML:

I did try using Q_INVOKABLE with no change in behavior. I should have mentioned that.

I see. Well I'm not sure, to be honest, but you could quickly check if it works with a regular method.
Also you could try/see if the comparison operators are registered with the meta-type system.
... although as I think of it, this doesn't make much sense, as QObjects are not meta-types to begin with ...

Really? Why is that?

Because QObjects are all different (i.e. they are identities)
https://doc.qt.io/qt-6/object.html#identity-vs-value

[kshegunov]

@mzimmers said in invoking QObject operators from JS/QML:

Is this not possible, or am I just doing something wrong?

Well ... if it ain't invokable (or a slot), I suppose it's hard for the engine to know it should be exposed to QML, right?
Although, having an equality operator for a QObject is very unusual ...

[mzimmers]

@kshegunov said in invoking QObject operators from JS/QML:

@mzimmers said in invoking QObject operators from JS/QML:

Well ... if it ain't invokable (or a slot), I suppose it's hard for the engine to know it should be exposed to QML, right?

I did try using Q_INVOKABLE with no change in behavior. I should have mentioned that.

Although, having an equality operator for a QObject is very unusual ...

Really? Why is that?

[kshegunov]

@mzimmers said in invoking QObject operators from JS/QML:

I did try using Q_INVOKABLE with no change in behavior. I should have mentioned that.

I see. Well I'm not sure, to be honest, but you could quickly check if it works with a regular method.
Also you could try/see if the comparison operators are registered with the meta-type system.
... although as I think of it, this doesn't make much sense, as QObjects are not meta-types to begin with ...

Really? Why is that?

Because QObjects are all different (i.e. they are identities)
https://doc.qt.io/qt-6/object.html#identity-vs-value