Ruoyu Sun's
Thoughts on design, code and venture capital

C#: 6 Years Later

17 Mar 2019

6 years ago, I wrote a post titled “6 Months with C#” to summarize my experience with the language. Since then, I haven’t programmed in C# professionally (I did do quite a few C# programming with my own hobby games using Unity and Godot).

Recently, I’ve picked up C# again for a work related project. The language (and its ecosystem) has changed a lot during the past 6 years and I’ve dropped down some quick notes of my experience with C# this time, just as a quick comparison to 6 years ago.

New Language Features

6 years ago I was writing C# 4.0 (.Net Framework 4). async/await was introduced in C# 5.0. My first experience using async/await is actually in in JavaScript. Both implementations are straightforward. And support has been expanding in the language (e.g. C# 7.1 allows async Main function). With the feature introduced a while ago, most of the C# libraries have caught up and provided decent API support.

Here’s a list of new features I find myself using quite a lot

I discover most of these new features by IDE telling me if things can be done with a newer and cleaner way. I will talk about IDE later.

.NET Core

In my previous post, my biggest complaint is that “C# is Windows only” - Mono was never a production grade runtime. With .NET Core, it is theoretically possible to “write Windows and run on Linux”. However, in practice, it still depends:

The C# project I am working on requires taking the game logic code written in .NET Framework 3.5 (Unity), making it Unity-independent and run in on a Linux server. Most of the C# works works “out of the box” when moving from .NET Framework 3.5 to .NET Core 2.2. There are some Unity related quirks that I have to deal with, some DLLs needs to be recompiled. Overall it has been a smooth ride.

Develop on Mac/Linux

My work laptop is a Macbook Pro. So when I start to work on the project on macOS. Six years ago, Visual Studio (+ Resharper) was pretty the only viable option if you want a powerful IDE. However, since Jetbrains introduced Rider, it has become a very competitive alternative. Furthermore, VSCode (+ Omnisharp) has come a long way. I use it for my own C# game projects and am pretty happy with it. And there’s Visual Studio for Mac, an evolved Monodevelop.

Overall, there’s no problem writing C# on non-Windows. However, I ended up installing Windows on my Mac and switch to Windows. The reason?

Deploy and Run on Linux

.NET Core comes with self-contained deployment, which makes it very easy to deploy on Linux. Whether you use machine images (like AMI) or containers, you can produce a self-contained binary with your CI pipeline and copy the executables over to the target to produce deployment image.

Six years ago, you could in theory deploy on Linux via Mono. However, Mono had some pretty noticeable performance issues compared to .NET Framework on Windows. So this time I decide to run a series of load testing for the .NET Core project (a UDP game server) on Linux (on a micro AWS EC2 instance running Ubuntu). The result has been quite good: the code is performant and there’re no serious GC issues.


Six years ago, I complained that .NET ecosystem is too Microsoft-centric. Six years later, this statement is probably still more or less true but the difference is that Microsoft is more “open”. Six years ago, the C# ecosystem was used to tie developers to the other (expensive) Microsoft platforms and solutions. Six years later, you can feel that Microsoft provides support and guidance to the prominent community-driven projects to grow the ecosystem. C# is no longer “vendor lock-in”, but rather an open platform itself.

So C# for Fun?

Six years ago, I would never use C# in a fun personal project. But things have changed. Since now most of my “fun” projects are game related, I actually use C# a lot:

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