Question

I have a method which returns the interface IObservable<A> (in silverlight) and wish to transforms this into another IObservable<B>?

So what do I need to put in place of ‘CONVERT_SOME_HOW’

public IObservable<Bar> Get(IEnumerable<object> @params)
{

    IObservable<Foo> fooObservable = _resources.Get(@params);
    IObservable<Bar> barObservable = CONVERT_SOME_HOW(fooObservable);

    return barObservable;
}

Answer 1

Just as you would in LINQ to Objects, use a projection:

var observableB = observableA.Select(a => new B(a));

(Obviously, adjust according to your conversion.)

That’s assuming I understand the question correctly. It’s not quite clear what you mean by “when the subscription to the first observer is executed”.