how to disconnect the method for a signal in qml？

Question

In QML, in some situations, I need to remove the old method to a signal and redefine a new method to handle the signal, a demo is as following:

import QtQuic         


        

Answer 1

You haven't used the explicit connect() function to begin with. To disconnect() a function, it has to have been connected explicitly using connect().

There is an example here that might help:

http://doc.qt.io/qt-5/qtqml-syntax-signals.html#connecting-signals-to-methods-and-signals

Answer 2

You can't disconnect the default signal handler onSignal: { do what ever }.

You can only dissconnect, when you have connected with onSignal.connect(say) beforehand. You could do this in Component.onCompleted.
If you use the syntax:

onSignal: say()

this equals

onSignal.connect(function() { say() })

and therefore you can't use onSignal.disconnect(say) as say was never connected. (I don't know whether it is connected to onSignal or to signal - both could be done manually, or whether it is not connected at all. You can't disconnect it, without having a reference to the implicitly created function.)

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In QML, the nicer way would be to stay declarative. For this you can use the Connections-construct:

Connections {
    target: mouse // set to null to disconnect (Qt<=5.6)
    onClicked: { do what ever }
    enabled: true // change this, when you want to disconnect it (Qt>=5.7)
}