IObservedChange <TSender,TValue> why not covariant now?

[DamianReeves]

There is a comment in the code (see below) saying that in the future IObservedChanged will be covariant, why in the future and now now?

    /// <summary>
    /// IObservedChange is a generic interface that replaces the non-generic
    /// PropertyChangedEventArgs. Note that it is used for both Changing (i.e.
    /// 'before change') and Changed Observables. In the future, this interface
    /// will be Covariant which will allow simpler casting between specific and
    /// generic changes.
    /// </summary>
    public interface IObservedChange<TSender, TValue> {...}

[anaisbetts]

Because in WP7 IObservable isn't Covariant, so it breaks everything. IObservable is Covariant on some platforms and not others. lolmicrosoft.

[DamianReeves]

That is horrible. So, in theory if I only cared about WPF, I could change this to covariant in my own fork just for WPF.

[anaisbetts]

@DamianReeves Sure, I don't think it would make your life harder wrt merging things from upstream either. Go for it.