public static IObservableResult <TResult> GetObservable <TCollection, TResult>(this TCollection collection, Func <TCollection, TResult> get, Action <TCollection, NotifyCollectionChangedEventArgs, Action> subscribeExtra = null)
where TCollection : INotifyCollectionChanged
{
subscribeExtra = subscribeExtra ?? ((c, e, a) => {});
var result = new ObservableValue <TResult>(get(collection));
collection.CollectionChanged += (sender, e) => {
result.Value = get(collection);
subscribeExtra(collection, e, () => result.Value = get(collection));
};
return(result);
}
public IObservableResult <TResult> GetObservable <TResult>(Func <T, TResult> get, Action <T, T, Action> subscribeExtra = null)
{
var result = new ObservableValue <TResult>(get(Value));
var lastValue = Value;
PropertyChanged += (sender, _) => {
var that = (ObservableValue <T>)sender;
result.Value = get(that.Value);
if (subscribeExtra != null)
{
subscribeExtra(that.Value, lastValue, () => result.Value = get(that.Value));
}
lastValue = Value;
};
return(result);
}