Quick introduction to Righthand.SharpRedux library

I’ve been experimenting with a redux implementation for .net lately and here is the current state.

The core library is quite functional and ready for a bit more serious test drive. There is also a visualizer, redux based, and with a frontend for WPF (other frontends can be added).

Available are two sample apps, Todo which is a WPF/MVVM/redux implementation of TodoMVC. And a dirty Playground sample.

Here are two screenshots from Todo sample and a brief introduction:

The application itself is on the left while visualizer is on the right. Visualizer is further composed of actions list and state|difference display. Above it shows current state after highlighted action. Value “[0] 1” in visualizer means list item with index 0 (when a list member) and item has an unique key with value 1 (when applicable).

Above the visualizer is showing state difference between the last action and previous one. You can also select any action from the list and click Reset to State which would rewind the state to one after that action.

But why would anybody bother with redux at all? The answer is logging, separation, unit testing and state rewind. Imagine you have an application that crashes – getting all the actions in proper order would give you the ability to reply exactly what user/application was doing until it crashed – even without any user intervention or feedback.

That’s it for a quick introduction. I’ll try to blog more, create more documentation about it, based also on feedback/interest. I’ll try using it in a real project when an occasion appears. Also visualizer can be and probably will be improved. Right now is something that works well enough for start.

Righthand.SharpRedux is open source and hosted on github and libraries will appear soon on NuGet. You can also get the Todo sample as a zip (.net 4.6.2 required),

Immutable types are based on Righthand.Immutable which is also hosted on NuGet. Visual Studio 2017 extension that creates immutable code is available at Marketplace. Righthand.Immutable is optional for SharpRedux and can be used standalone.


App icons missing after upgrading to iOS 11/Xamarin

I have an Xamarin iOS project and developing in Visual Studio 2017 and have app icons in an asset. Since I’ve upgraded to XCode 9/iOS11 the app icons aren’t included anymore and Application Uploader would throw a ton of errors at me about the missing icons. Before XCode 9 it worked though.

Xamarin describes upgrading issues to iOS 11 here and there but nothing much for Visual Studio 2017 – a key is missing in Info.plist they say. But what key?

It turns out the solution is a really simple one. Open iOS project in Visual Studio 2017, open Info.plist in editor, go to Visual Assets and make sure that App Icons source is pointing towards correct asset (with app icons).

It will generate this Info.plist key and value (value might differ, based on where your app icons are):


This value can be added manually, as well, if you know what to add.

Android Windows

Good bye Visual Studio Emulator for Android and hello problems

I recently tested a prototype of a Xamarin Android app that should run on Android 4.1+. So I fired up Visual Studio Emulator for Android and saw that API level 16 (4.1) is missing from the list. The oldest is level 17/4.2.

Since they have a nice smiley icon for feedback I wrote a quick request to include level 16 as well since a lot of apps are targeting 4.1+, not just me.

The shocker came few seconds later in a form of an automated e-mail response (emphasis mine):


This is an automated message. Unfortunately, we have no plans to publish Android images past 4.4. We recommend that you try Google or GenyMotion’s emulator for future images of the Android operating system.
When we first released the Visual Studio Android emulator, the Google emulator was slow, out-of-date, and a significant source of pain for mobile developers. In addition to the great work performed by GenyMotion, the Visual Studio Android Emulator proved that emulators can be fast, productive tools for mobile development.
Since then, Google has responded to developer feedback by increasing their investment in their tools. The next generation Google Android Emulator has closed the feature gap that previously differentiated Visual Studio’s emulator. Google’s emulator has become much faster and more feature rich.
We also know that, for mobile developers, authenticity is key. We believe that Google, as the platform owner, is best positioned to provide ongoing support for new versions of the platform in a way that accurately and authentically reflects the real-world behavior on devices.
For developers like you who’ve come to love and depend on the VS Android Emulator, thank you! We will continue to support in-market platform images according to Visual Studio’s generous support policy. However, Microsoft will no longer produce new Android images for the VS Android Emulator. We consider this a successful project that has come to a natural conclusion.
Happy coding!

Wait, what? First time I heard that VSE4A is no more. Which wouldn’t be that tragic if Hyper-V wasn’t involved. See, VSE4A is the only Android emulator based on Hyper-V. Why do I even care? Oh, I do and you should do as well. When Hyper-V is enabled it doesn’t allow any other virtualization host to run. Sure, you can disable Hyper-V (reboot required) and go with Google’s Emulator or a better one from Genymotion. But then you can’t run Docker, Windows Emulator and  your other Hyper-V guests at the same time. More here.

Happy coding, indeed.

There is light of hope though. Miguel tweeted that there might be a solution in the future

Hopefully that’s the case. In the meantime VSE4A still works and is available for download, it is just missing images, specially newer ones (latest is API level 23 aka 6.0).

But at the end I’d really like Microsoft to address the cause of this blunder: the monopolistic Hyper-V behavior on desktop. If Windows virtualization worked like others do (“live and let live”) there won’t be a problem whatsoever. The way it works now it makes sense on servers, not on desktops.

But instead of fixing that, Microsoft choose to create all imaginable emulators on top of Hyper-V. What could go wrong?


Webpack’s cheap-module-eval-source-map requires a plugin

I’ve started experimenting with React and consequently Webpack. As a base I
picked Cory House’s excellent “Building Applications with React and Redux in ES6” course on Pluralsight (disclaimer: as a MS MVP I get free subscription). BTW Pluralsight is a really good learning content delivery – so much good stuff there.

Anyway, I was building upon Cory’s project and at some time I decided to update packages to their latest version (by updating versions in package.json, deleting node_modules and running npm update). Everything went smooth except that I noticed that debugging in browsers stopped for some reason. Breakpoints weren’t observed, sources weren’t shown. The later proved as hint what to look for – devtool settings in webpack.config.js that is.

It turns out that Cory was using cheap-module-eval-source-map which was working with the original version of webpack. However after updating it didn’t work anymore.

The solution is rather simple: add a new plugin to webpack.config.js:

new webpack.EvalSourceMapDevToolPlugin()

Looks like that folks at webpack decided to put this functionality into a separate plugin at a certain point in time (I didn’t follow its progress). And no, the solution isn’t mine. Instead I found it at this stackoverflow thread.


LINQPad, LLBLGENPro and Npgsql

If you want to test LLBLGenPro/Npgsql queries with LINQPad, and you really should, you have to follow these steps.

  1. Install the official LLBLGenPro driver for LINQPad (Add connection, View more drivers…, …)
  2. Reference LLBLGenPro generated assemblies (connection configuration), enter proper connection strings and, albeit optional, provide a .config file that contains DBProviderFactiories entry for Npgsql (watch out for version number)
  3. Once connection is created, add Npgsql NuGet package to query. The version should match the one configured in step #2.

And voila, beautiful interactive queries at your disposal. You can even use ORM Profiler.

Sample Npgsql factory entry:

      <!-- PostgreSql -->
      <add name="PostgreSql Client Data Provider" invariant="Npgsql" description=".Net Framework Data Provider for PostgreSql" type="Npgsql.NpgsqlFactory, Npgsql, Version=, Culture=neutral, PublicKeyToken=5d8b90d52f46fda7" />
.netcore Docker Visual Studio

A solution to Visual Studio Tools for Docker debugging problem

I you have problems with debugging your .net core application using Visual Studio Tools for Docker – the app simply stops at start and you see a lot of Trying to connect to http://localhost (N/120) messages (where N = [1,120]) – then you might be interested in the workaround.
Which, as it turns out, is quite simple.
Open docker-compose.debug.yml file and simply remove the volumes section:
      – .:/app

Then you can debug it normally.

See the original solution post named Trying to connect to http://localhost/ (1/XXX) in Q and A section.

.netcore Docker Presentation

Content for my Cxncel “docker for developers” presentation (Slovene)

I’ve uploaded all the sources and slides of my Cxncel presentation to GitHub. Enjoy.


Content for my Mono, Docker, 3.14, WebAPI on NTK 2016 presentation

I’ve uploaded all the demo content and presentation slides.

Source files are on github, Docker images are on Docker hub. Give it a try.

.net Announcement C# Docker Linux Mono

Mono, Docker, 3.14, WebAPI on NTK 2016

This year I’ll be presenting at Microsoft’s NT Konferenca as I do every year.

As the topic I’ve picked my experience of using Docker I gathered from a real world example. I’ve been building an application that is a combination of PostgreSQL database, Mono/NGINX/WebAPI on server and UWP/Windows10 on client. Server side supports various OS. Target is Linux but it should run on Windows without issues. The combination of server OS and server tools choice drives costs down significantly on one hand and makes it versatile on the other.

Docker helps a lot through the development and final deployment in production. And that’s what talk is all about. 3.14 will play a role as well – showing that there is almost no HW restriction for such a combination on server side. We’ll build and deploy the application through rich demos.

See you there, Monday at 9:00.


Strong typing DisplayAttribute reference to Resources

Let’s say there is a decorated member with DisplayAttribute in code, i.e.:

public enum SomeEnum
	[Display(Name = "ResourceKey", ResourceType=typeof(Resource)]

That’s all right except for one problem. If Name is mistyped or given resource key is latter changed then DisplayAttribute will point to an incorrect value and compiler won’t help. Resources designer doesn’t help as well, at least indirectly, because it doesn’t generate externally usable key names. It generates strong typed getters though, like:

internal static string ResourceKey {
        get {
             return ResourceManager.GetString("ResourceKey", resourceCulture);

So, these getters are the only strong typed artifact that can be used to achieve strong typed reference. Luckily there is one C# (also VB) feature that was introduced in 6.0 and it is very useful in improving strong typed aspect of code. it is nameof keyword. it is evaluated at compile time and replaces the given expression with a string representation.

In other words, the sample above can be rewritten in strong typed manner:

public enum SomeEnum
	[Display(Name = nameof(Resources.ResourceKey), ResourceType=typeof(Resource)]

This way the name is guaranteed to match since it is checked at compile time. So, no more mismatch between the key name and reference to it.

Of course, nameof can be used in many other places. Most notably in INotifyPropertyChanged/MVVM scenario.