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Exposing VB.NET object to COM in the old C format using Interop

P: n/a
I need to make the VB.NET object callable from a program called Trade Station. It is a stock analysis and trading tool that is very importiant to my company. They have a scripting languge called easy language that is built into the system. It is supposed to be capable of extending itself by calling external DLLs. It is very picky about what DLLs it will see though

Others have had success using C++ to write a DLL that will work with Easy Language, but I am hitting a brick wall with VB. I am not a strong C++ programmer, but I am very good at VB. I am hoping to find a way to make interop expose my VB DLL in the same way that the C++ DLL is exposed. Here is a snippet of code that is from a working C++ DLL. I hope it is meaningful. I am not sure :-(

// stdafx.h : include file for standard system include files
// or project specific include files that are used frequently, bu
// are changed infrequentl

#pragma onc

#define WIN32_LEAN_AND_MEAN // Exclude rarely-used stuff from Windows header
// Windows Header Files
#include <windows.h

// TODO: reference additional headers your program requires her
#define dll_entry( type ) extern"C" type __stdcal

// a.cpp : Defines the entry point for the DLL application

#include "stdafx.h
#import "c:\Program Files\TradeStation\Program\TSKit.dll" no_namespac
#import "D:\documents\projects\TradeStationInterop\CSharp\ bin\Release\CSharp.tlb

DWORD ul_reason_for_call,
LPVOID lpReserve
return TRUE
double __stdcall MyTest(IEasyLanguageObject *pEL, int iNBars

CSharp::_Class1 *com_ptr
CSharp::_Class1Ptr p(__uuidof(CSharp::Class1))
com_ptr = p
double d = com_ptr->TestDouble()

return d
// stdafx.cpp : source file that includes just the standard include
// a.pch will be the pre-compiled heade
// stdafx.obj will contain the pre-compiled type informatio

#include "stdafx.h


Jul 21 '05 #1
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P: n/a

Thanks again for your post. Now I understand, you want to call a .NET
component from a scripting language which only supports calling unmanaged
DLL (with LoadLibrary, GetProcAddress calls). Now I'd like to share the
following information with you:

We are not able to expose VB .NET component to the unmanaged world like the
C++ unmanaged DLL directly. To work around the problem, you will need to
create an additional C++ unmanaged DLL which uses COM Interop to consume
.NET components and export functions to Easy Language scripting.

COM Interop Sample: COM Client and .NET Server

Please feel free to let me know if you have any problems or concerns.


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Jul 21 '05 #2

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