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

Read more: Brad Wilson

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