Question

I’d like to dynamically load and use a .Net assembly created in C# from a Delphi Win32 application. My classes and interfaces are marked as ComVisible, but I would like to avoid registering the assembly. Is this possible?

P.S. I found here link text another good discussion on the topic, but it is more around hosting the CLR. Which begs a question – why would you host CLR versus using ClrCreateManagedInstance?

Answer 1

Strangely enough, I couldn’t find an answer on StackOverflow, and there is not much on the Net, especially for Delphi. I found the solution from examples posted here. Here’s what I got at the end:

function ClrCreateManagedInstance(pTypeName: PWideChar; const riid: TIID; out ppObject): HRESULT; stdcall; external 'mscoree.dll';  procedure TMyDotNetInterop.InitDotNetAssemblyLibrary; var   MyIntf: IMyIntf; hr: HRESULT; NetClassName: WideString; begin //Partial assembly name works but full assembly name is preffered.     NetClassName := 'MyCompany.MyDLLName.MyClassThatImplementsIMyIntf,           MyCompany.MyDLLName';     hr := ClrCreateManagedInstance(PWideChar(NetClassName), IMyIntf, MyIntf);     //Check for error. Possible exception is EOleException with ErrorCode     //FUSION_E_INVALID_NAME = $80131047 2148732999 : The given assembly name      //or codebase was invalid.     //COR_E_TYPELOAD = $80131522 - 'Could not find or load a specific type      //(class, enum, etc)'     //E_NOINTERFACE = $80004002 - 'Interface not supported'.     OleCheck(hr); end; 

BTW, depending on the situation, you might want to load mscoree.dll dynamically, because it might be not present on the system (XP with no .Net Framework)

EDIT: Unfortunately, this was deprecated and stopped working with .Net4 as I just found out. This leaves only two options – CLR hosting and unmanaged export. Also, debugging of .Net4 COM code is broken.