Getting Started

Question

Trying to play around with Rx v2.0 Beta and need some help.

I have the following IObservable setup...

private readonly Subject<int> _IncomingValue = new Subject<int>();

public IObservable<int> IncomingValue { get { return _IncomingValue.AsObservable(); } }

I have a Button click event that I want to begin looking for a certain value on IncomingValue and would also like to have a Timeout of 5 seconds.  If the Timeout occurs, it will display "Time is up" in a TextBox using WPF and unsubscibe.

I have another Button click event that will use the IncomingValue.OnNext(iNewValue) to update to the value I'm looking for.

Once the correct value is sent, I would like to unsubscribe so future events won't be triggered.

How would I write this basic code?  Any solutions?  TIA.

Answer 1

Hi,

Here's a blog post that contains links to get started learning Rx:

http://davesexton.com/blog/post/resources-for-learning-rx.aspx

For your particular questions, I highly recommend reading Rx's conceptual documentation.  All of it's worth reading, but you may want to start here:

http://msdn.microsoft.com/en-us/library/hh242972(v=vs.103).aspx

Also, you should try searching this forum if you haven't already.  Your questions are a bit vague, but I'm sure they've been answered here before.

Here are some hints:

> I have a Button click event that I want to begin looking for a certain value on IncomingValue

Consider using the Where operator.

> Timeout of 5 seconds.

Consider using the Timeout operator.

> If the Timeout occurs, it will display "Time is up" in a TextBox using WPF

Consider using the Catch operator.  You may also want to consider using some type for T (of the Subject<T>) that may pass either success information or timeout information to subscribers.  For example, see the Either type in Rxx; e.g., Either<int, TimeoutException>.  Or you could write directly to the TextBox as a side-effect in your Catch handler, though I don't recommend it.

> Once the correct value is sent, I would like to unsubscribe so future events won't be triggered.

Consider using the Take(1) operator.

- Dave

---

http://davesexton.com/blog