Selecting CLR Version From Unmanaged Host

I just saw this go by on an internal DL and it seemed worth documenting.

What is the correct way determine what framework version is installed on a computer to choose the correct CLR hosting approach?

I would like to use CLR 4.0 runtime if CLR 4.0 is installed (and use CLRCreateInstance -> ICLRMetaHost->GetRuntime), but if it is not installed, I’d use CorBindToRuntimeEx.

According to MDSN, GetCORVersion is deprecated. What should I use instead? ICLRRuntimeInfo::EnumerateInstalledRuntimes would not work in an environment where CLR 4.0 is not installed, correct?

I would like my code to work in CLR 2.0+ environment.

And the answer:

• LoadLibrary mscoree
• GetProcAddress for CLRCreateInstance. If you get NULL, fall back to legacy path (CorBindToRuntimeEx)
• Call CLRCreateInstance to get ICLRMetaHost. If you get E_NOTIMPL, fall back to legacy path (same as above)
• Otherwise, party on the ICLRMetaHost you just got

Comments

[Louis]

My kingdom for sample code...

Rick Strahl has some samples here:
http://www.west-wind.com/wconnect/weblog/ShowEntry.blog?id=631

But it looks like he's using the deprecated APIs for .NET 2.0. I'm on a platform where I know at least .NET 3.5 will be installed. Or should be. If not, I fail gracefully.

[Louis]

OK. I found some very good sample code for loading the Runtime host and calling methods on a .NET DLL from an unmanaged app. There are two samples in the All-in-One Code Framework. One that targets CLR 1.0/2.0 and another that shows 2.0/4.0.