问题
Are all the additions to C# for version 4 (dynamic, code contracts etc) expected to run on the current .NET CLR, or is there a planned .NET upgrade as well?
回答1:
C# 4 will require the .NET 4.0 CLR.
回答2:
Well, .NET 4.0 will require CLR 4.0; however, it is a little harder to answer what parts of C# 4.0 will work on .NET 2.0/3.x. We can hope that VS2010 will still be multi-targeting(I don't have the CTP "on me" so to speak, so I can't check...). But some of the language features don't seem hugely tied to the runtime (named parameters, some of the COM changes such as "ref") - so I can't think of a good reason why they wouldn't be available when talking to .NET 2.0/3.x. I haven't checked, though.
However, as with C# 3.0, some of the features are tied to the runtime - in particular dynamic.
I need to dig out the CTP and have another play, methinks...
回答3:
You don't have to wait for 4.0 to use Code Contracts as it runs on .NET 3.5, the download link for the academic preview release is here.
来源：https://stackoverflow.com/questions/336138/c-sharp-4-and-clr-compatibility