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AsyncBridge? Async on .NET 4.0 using VS11

I’ve just found something quite cool. It’s a code snippet that lets you use the real VS 11 C#5 compiler to write code that uses the async and await keywords, but to target .NET 4.0. It was published by Daniel Grunwald (from SharpDevelop).

That means I can stop using the Async CTP for VS2010, which is not at all supported anymore, and a pain to install if you have windows updates turned on. Obviously I couldn’t ask all my users to install .NET 4.5 beta, but .NET Demon is a VS 2010 extension, so we already have .NET 4.0. At the time of writing, VS11 is in beta still, but hopefully it’s stable enough for my team to use!

I would have written the code myself, but I had the wrong impression that the C# 5 beta compiler only looked in mscorlib for the helper classes it needs to implement async methods. Turns out you can provide them yourself.

You can get the code here:
https://gist.github.com/1961087

You just add it to your project, and the compiler will apparently pick it up and use it to implement async/await. I’m at my parents’ place for Easter without access to a machine with VS 11 to try it out. Let me know whether you get it to work!

This reminds me of LINQBridge, which let us use C# 3 LINQ, but only require .NET 2. We should stick up a webpage to explain, with a nice easy dll, put it in nuget, and call it AsyncBridge.

If you were really enthusiastic, you could re-implement the skeleton of the Task Parallel Library against .NET 2 to use async/await without even requiring .NET 4. Our usage stats suggest that practically everyone that uses Red Gate tools already has .NET 4 installed though, so I don’t think I’ll go to the effort.