.NET Information center: Selecting CLR Version From Unmanaged Host

Wednesday, April 21, 2010

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