UniRx Before and After Example: loading a catalog from a web API while falling back to two on-disk sources.

ObservablesExamples.cs

// First the solution as provided, using UniRx.
public class ObservablesExample {

	// The CatalogInfo, this is non-null immediately after calling LoadCatalog().
	public IObservable<CatalogInfo> CatalogInfo;
	
	// Helper methods, where the work of loading is done.
	// UniRx makes it painless to execute these off the main thread.
	// Errors are handled by Observable.OnError
	private IObservable<CatalogInfo> LoadFromPlayFab() { /* ... */ }
	private IObservable<CatalogInfo> LoadFromDisk()    { /* ... */ }
	private IObservable<CatalogInfo> LoadFromAsset()   { /* ... */ }

	public void LoadCatalog() {
		CatalogInfo = PlayFabInit.PlayFabId
			.ContinueWith(LoadFromPlayFab())
			.Catch((Exception e) => LoadFromDisk())
			.Catch((Exception e) => LoadFromAsset());
	}
}

// And now the solution using standard C#.
public class NoObservablesExample {

	// The CatalogInfo, this is null for some indeterminate time after calling LoadCatalog().
	public CatalogInfo CatalogInfo;
	
	// Helper methods, where the work of loading is done.
	// Errors throw Exceptions
	private CatalogInfo LoadFromPlayFab() { /* ... */ }
	private CatalogInfo LoadFromDisk()    { /* ... */ }
	private CatalogInfo LoadFromAsset()   { /* ... */ }

	public void LoadCatalog() {
		new Thread(LoadCatalogFirstStep).Start();
	}

	private void LoadCatalogFirstStep() {
		if (PlayFabInit.PlayFabId != null) {
			// Assume PlayFabId is null if we're not connected.
			CatalogInfo = LoadCatalogFallback();
			return;
		}
		
		try {
			CatalogInfo = LoadFromPlayFab();
		} catch (Exception) {
			CatalogInfo = LoadCatalogFallback();
		}
	}

	private CatalogInfo LoadCatalogFallback() {
		try {
			return LoadFromDisk();
		} catch (Exception) {
			return LoadFromAsset(); // Assuming this never fails.
		}
	}
}