Exporting classes to .Net world from a regular DLL

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Note Myself - 12 Jun 2007 03:41 GMT

I am writing a C++ library. I know that I can export classes through
dllexport keyword. However, we also need this library to be accessible from
.Net applications. Our original plan is to package it using COM. Is there a
way to expose these classes without adding COM layer? Thanks

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Brian Muth - 12 Jun 2007 05:31 GMT

>I am writing a C++ library. I know that I can export classes through
>dllexport keyword. However, we also need this library to be accessible from
>.Net applications. Our original plan is to package it using COM. Is there a
>way to expose these classes without adding COM layer? Thanks

Yes, you can use a C++ Interop (or you can use PInvoke directly) to interact
with unmanaged code that uses dllexport.

You can read more about it here:
http://msdn2.microsoft.com/en-us/library/2x8kf7zx(vs.80).aspx

A newsgroup that is dedicated to this subject is
microsoft.public.dotnet.framework.interop.

HTH,

Brian

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Alexander Nickolov - 12 Jun 2007 18:06 GMT

Brian, are you sure P/Invole supports non-C DLL exports?

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=====================================
Alexander Nickolov
Microsoft MVP [VC], MCSD
email: agnickolov@mvps.org
MVP VC FAQ: http://vcfaq.mvps.org
=====================================

>>I am writing a C++ library. I know that I can export classes through
>>dllexport keyword. However, we also need this library to be accessible
[quoted text clipped - 13 lines]
>
> Brian

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Brian Muth - 12 Jun 2007 19:24 GMT

> Brian, are you sure P/Invole supports non-C DLL exports?

I think it has to be a C-style DLL export. Thanks for the clarification.

http://msdn2.microsoft.com/en-us/library/ms235282(VS.80).aspx

Frankly, I'd be inclined to put a COM wrapper around the C++ library. I'm
sure you feel the same way.

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MrAsm - 12 Jun 2007 20:21 GMT

>Frankly, I'd be inclined to put a COM wrapper around the C++ library. I'm
>sure you feel the same way.

I agree that the more robust way to reuse C++ libraries is wrapping
using COM. e.g. a DLL which exports C++ classes, built with
VS.NET2003, may have problems if used (without rebuilding) with
VS2005. If the C++ library has a COM wrapper around, those problems do
not exist.
COM is really a very good technology for binary code reuse, IMHO.

MrAsm

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Exporting classes to .Net world from a regular DLL

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