RxTraceExtensions.cs

public static class RxExtensions
{
	/*
	.TraceWithName(nameof(Reachability))
	> Rx Reachability#1: Subscribe()
	> Rx Reachability#1: OnNext(False)

	.TraceWithName(nameof(reach.WhenConnectedChanged), this)
	> Rx AppDelegate_WhenConnectedChanged:2037545460#1: Subscribe()
	> Rx AppDelegate_WhenConnectedChanged:2037545460#1: OnNext(connected)
	*/

	public static IObservable<TSource> Trace<TSource>(this IObservable<TSource> source, object @class)
	{
		return Trace(source, @class.GetType().Name, @class.GetHashCode().ToString());
	}

	public static IObservable<TSource> TraceWithName<TSource>(this IObservable<TSource> source, string name)
	{
		return Trace(source, $"{name}");
	}
	public static IObservable<TSource> TraceWithName<TSource>(this IObservable<TSource> source, string name, object @class)
	{
		return Trace(source, $"{@class.GetType().Name}_{name}", @class.GetHashCode().ToString());
	}

	// http://www.lavinski.me/debugging-rx-with-seq/
	private static IObservable<TSource> Trace<TSource>(this IObservable<TSource> source, string name, string hash = null)
	{
		var id = 0;
		return Observable.Create<TSource>(observer =>
		{

			var itemId = ++id;

			Action<string, object> trace =
				(method, value) => Debug.WriteLine(
					$"Rx {name}{(hash != null ? ":" + hash : "")}#{itemId}: {method}({value})"
				);

			trace("Subscribe", null);

			var disposable = source.Subscribe(
				onNext: v => { trace("OnNext", v); observer.OnNext(v); },
				onError: e => { trace("OnError", e); observer.OnError(e); },
				onCompleted: () => { trace("OnCompleted", null); observer.OnCompleted(); });

			return
				() => { trace("Dispose", null); disposable.Dispose(); };
		});
	}
}