No way to declaratively instantiate Path elements in ShapePath

When using Shape, it would be nice to be able to construct a ShapePath using data from a model. For example, something like this:

Shape {
    ShapePath {
        Instantiator {
            model: someModel // Anything which implements Qt model API  
            PathLine {
                x: xValue // data from item in model
                y: yValue // data from item in model
            }
        }
    }
}

At the moment, this doesn't work, because it tries to add the Instantiator to the pathElements property of ShapePath and can't because it isn't a PathElement itself.

I haven't been able to find any other way of declaratively building up a ShapePath using data from a model. I believe it would make Shape and ShapePath much more flexible: Having to define all the line segments ahead of time is very limiting and rarely useful in practice.