Is it possible to host the CLR in a C program?

Question

Every example I can find is in C++, but I'm trying to keep my project in C. Is it even possible to host the CLR in a C program?

If so, can you point me to an example?

Putrid

CLR API is a COM API. Basically, you should be calling COM interfaces in C. – Oxpecker

... and for doing so, you can find an article here: codeproject.com/KB/COM/com_in_c1.aspx – Oxpecker

I'm going to be honest and say that I have absolutely no idea what I'm doing. I'm a C# guy, not a C guy, so that article makes little sense to me. Is there a specific example of hosting the CLR, creating a .NET object instance, and executing a method on it (which I realize is probably fairly complicated)? – Putrid

In particular, you don't need the COM in Plain C article at all, hosting the CLR is much easier. It's nice overview article though. – Maidstone

Answer 1

As the above comments hint, there is a set of COM APIs for hosting the CLR, and you should be able to call these COM APIs from both C and C++.

As an example, below is a quick piece of (untested) C code that shows how to start up the CLR and execute a static method of a class in a managed assembly (which takes in a string as an argument and returns an integer). The key difference between this code and its C++ counterpart is the definition of COBJMACROS and the use of the <type>_<method> macros (e.g. ICLRRuntimeHost_Start) to call into the CLR-hosting COM interface. (Note that COBJMACROS must be defined prior to #include'ing mscoree.h to make sure these utility macros get defined.)

#include <windows.h>

#define COBJMACROS
#include <mscoree.h>

int main(int argc, char **argv)
{
    HRESULT status;
    ICLRRuntimeHost *Host;
    BOOL Started;
    DWORD Result;

    Host = NULL;
    Started = FALSE;

    status = CorBindToRuntimeEx(
                 NULL,
                 NULL,
                 0,
                 &CLSID_CLRRuntimeHost,
                 &IID_ICLRRuntimeHost,
                 (PVOID *)&Host
                 );
    if (FAILED(status)) {
        goto cleanup;
    }

    status = ICLRRuntimeHost_Start(Host);
    if (FAILED(status)) {
        goto cleanup;
    }

    Started = TRUE;

    status = ICLRRuntimeHost_ExecuteInDefaultAppDomain(
                 Host,
                 L"c:\\path\\to\\assembly.dll",
                 L"MyNamespace.MyClass",
                 L"MyMethod",
                 L"some string argument to MyMethod",
                 &Result
                 );
    if (FAILED(status)) {
        goto cleanup;
    }

    // inspect Result
    // ...

cleanup:
    if (Started) {
        ICLRRuntimeHost_Stop(Host);
    }

    if (Host != NULL) {
        ICLRRuntimeHost_Release(Host);
    }

    return SUCCEEDED(status) ? 0 : 1;
}

This sample should work with .NET 2.0+, although it looks like .NET 4.0 (not yet released) has deprecated some of these APIs in favor of a new set of APIs for hosting the CLR. (And if you need this to work with .NET 1.x, you need to use ICorRuntimeHost instead of ICLRRuntimeHost.)

Adlib

Any guess why this won't work: #21537838 ? – Beauvoir