Xamarin.Forms Bindable Properties

Question

It may sound like a dumb question but why are bindable properties static?

public static readonly BindableProperty MapSpanProperty = BindableProperty.Create(
    propertyName: "MapSpan",
    returnType: typeof(MapSpan),
    declaringType: typeof(BindableMap),
    defaultValue: null,
    defaultBindingMode: BindingMode.TwoWay,
    propertyChanged: MapSpanPropertyChanged);

public MapSpan MapSpan
{
    get
    {
        return (MapSpan)GetValue(MapSpanProperty);
    }
    set
    {
        SetValue(MapSpanProperty, value);
    }
}

I have this code and it works just fine if I make the bindable property static, otherwise, it doesn't work. If I make this bindable property static it means, let's say if I have 2 maps opened at the same time, that this value will be the same on both if I set it on one of them?

Answer 1

As far as I understand, it's static just for get describing data before moment of creation. But it's not being used as static. BindableObject base class define INSTANСE of Dictionary<BindablePropery, BindablePropertyContext>. BindablePropertyContext contains our value. It means that each our class has static BindablePropery, but every of them get it's own context from it's own dictionary.