programatically change the function associated with a property change

Cyrille de Brebisson

Hello,

I know how to use qt.bindings on a property, but here, I need to programmatically assign a function to a property change.

I am trying to do:

    onSomeEvent: onVisibleChangedChanged= Qt.binding(function () { something() })

But the qml system does not seem to like this and throws a
qrc:/qml/main.qml:612: TypeError: Cannot assign to read-only property "visibleChanged"
error.

Any guidance on how to handle this?
Thanks,
Cyrille

Pablo J. Rogina

@cyrille-de-brebisson said in programatically change the function associated with a property change:

I need to programmatically assign a function to a property change.

What could be your use case?
What is the condition you'll use to go with one function or the other?

Cyrille de Brebisson

Hello,

I need to do something on the property change, but only after the application has fully loaded...
so I am trying to set this "binding" in the component.onCompleted function...
Of course, I could add a boolean property to the original component, and do the action onVisibleChanged only when said boolean is true, however, I was trying to use a different method.

Cyrille

IntruderExcluder

This isn't a good idea, but if you really want such behavior, here is some magic:

ApplicationWindow {
    id: root
    visible: true
    width: 400
    height: 680

    property var func: function() {console.log("Hello!")}

    Button {
        id: b1
        text: "Test"
    }

    Button {
        y: 50
        text: "Magic"
        onClicked: {
            b1.clicked.disconnect(root.func);
            b1.clicked.connect(function(){console.log("Cya!");});
        }
    }

    Component.onCompleted: {
        b1.clicked.connect(root.func);
    }
}

Hovewer, you cannot disconnect signals which are binded to signals (onClicked) for example, I think this is because they sorta anonimous.