Check if an AsyncSubject hasn't fired - system.reactive

Question

AsycSubject<Unit>() sub;
// stuff
if(!sub.HasFired())
// Do stuff
Current best attempt is:
public static bool HasFired<T>(this AsyncSubject<T> sub)
{
AsyncSubject<bool> ret = new AsyncSubject<bool>();
sub.Timeout(TimeSpan.FromMilliseconds(20))
.Subscribe(_ =>
{
ret.OnNext(true);
ret.OnCompleted();
},
ex =>
{
ret.OnNext(false);
ret.OnCompleted();
});
return ret.First();
}
But it feels very ugly and long. I suspect I'm missing something simple. Any suggestions?

Answer 1

It's easier to wrap around the existing AsyncSubject and add the required state.
public class AsyncSubjectEx<T> : ISubject<T>, IDisposable
{
AsyncSubject<T> Subject = new AsyncSubject<T>();
public bool HasValue { get; protected set; }
public object Gate = new object();
public void OnCompleted()
{
Subject.OnCompleted();
}
public void OnError(Exception error)
{
Subject.OnError(error);
}
public void OnNext(T value)
{
lock (Gate)
{
Subject.OnNext(value);
HasValue = true;
}
}
public IDisposable Subscribe(IObserver<T> observer)
{
lock (Gate)
return Subject.Subscribe(observer);
}
public void Dispose()
{
Subject.Dispose();
}
}
Ironically, the original AsyncSubject upon reflection shows that there is a hasValue field, but it doesn't happen to be exposed. Consider reporting this to the Rx team - might be useful sometime.