How to override a function, but call the base-object's version with no object id

I'm sure that you can do this, but I can't find how.

I need to override the open() method in a Popup-derived object in order to pass it a parameter. Here is a minimized sample of main.qml:

// main.qml
    import QtQuick 2.15
    import QtQuick.Window 2.15
    import QtQuick.Controls 2.5
    
    Window {
        width: 640
        height: 480
        visible: true
        title: "Call a base-object's function in an override"
    
        MyPopup {
            id: mypopup
            anchors.centerIn: parent
        }
    
        Button {
            text: "Say hi."
            onClicked: mypopup.open("hi")
        }
    }

And here is my new object, derived from Popup:

// MyPopup.qml
import QtQuick 2.0
import QtQuick.Controls 2.5

Popup {
    Text {
        id: greeting
        text: "bye"
    }

    function open( newText ) {
        greeting.text = newText
        Popup.open()                  <-- This is what I can't figure out
    }
}

If the base object had an id, then I would use it here, but the base class, Popup, is not instantiated. So how would I access its version of open()?

When I tried Popup.open(), as above, I was met with the error:

qrc:/MyPopup.qml:12: TypeError: Property 'open' of object [object Object] is not a function

When I tried Popup:open(), I got:

qrc:/MyPopup.qml:0: RangeError: Maximum call stack size exceeded.

which means the derived version of open() was calling itself.

So how do I call Popup's version of open()?

QML does not allow to override functions, it can only be customized by changing or creating properties and creating new functions.

On the other hand the ids have a scope so it is valid to set ids in the components and these will have meaning in the component.

In your case there are the following possible solutions:

1. Create a new function:

MyPopup.qml

import QtQuick 2.0
import QtQuick.Controls 2.5

Popup {
    id: root
    property alias text: greeting.text
    Text {
        id: greeting
        text: "bye"
    }
    function foo(newText){
        greeting.text = newText
        root.open()
    }
}

main.qml

// ...
onClicked: mypopup.foo("hi")
// ...

2. Expose the text as a new property (such as via an alias)

MyPopup.qml

import QtQuick 2.0
import QtQuick.Controls 2.5

Popup {
    id: root
    property alias text: greeting.text
    Text {
        id: greeting
        text: "bye"
    }
}

main.qml

// ...
Button {
    text: "Say hi."
    onClicked: {
        mypopup.text = "hi"
        mypopup.open()
    }
}
// ...