internal static IObservable <EventPattern <PropertyChangedAndValueEventArgs <TProperty> > > ObservePropertyChangedWithValue <TNotifier, TProperty>(
this TNotifier source,
PropertyPath <TNotifier, TProperty> propertyPath,
bool signalInitial = true) where TNotifier : INotifyPropertyChanged
{
var wr = new WeakReference(source);
var observable = source.ObservePropertyChanged(propertyPath, false);
return(Observable.Defer(
() =>
{
var withValues =
observable.Select(
x =>
new EventPattern <PropertyChangedAndValueEventArgs <TProperty> >(
x.Sender,
new PropertyChangedAndValueEventArgs <TProperty>(
x.EventArgs.PropertyName,
propertyPath.GetValue((TNotifier)wr.Target))));
if (signalInitial)
{
var valueAndSource = propertyPath.GetValueAndSender((TNotifier)wr.Target);
var current =
new EventPattern <PropertyChangedAndValueEventArgs <TProperty> >(
valueAndSource.Source,
new PropertyChangedAndValueEventArgs <TProperty>(
propertyPath.Last.PropertyInfo.Name,
valueAndSource.Value));
return Observable.Return(current).Concat(withValues);
}
return withValues;
}));
}
