Passing C# class between C++ functions

Question

I am wondering if it is possible to pass my invoked C# object between c++ functions? I can already call my C# dlls from my native code, but now I need to pass a object between c++ functions which also means that I need to declare it in the header file...

When defining it in my header file I get the following error:

BOOL Exists(Api ^api);

Error   60  error C3395: 'ApiBase' : __declspec(dllexport) cannot be applied to a function with the __clrcall calling convention

Does anyone know how I should handle this in my header?

BOOL Exists(Api ^api); is intended to be a part of native dll's api? — Evgeny Timoshenko
– Evgeny Timoshenko, Commented Nov 26, 2013 at 9:58
@johny Yes it is. The problem is that I cant remove the dll export because I am also wrapping the c++ code in my tests which is written in C#. Sorry if you missunderstand me somehow. I'm not a c++ master — James Ford
– James Ford, Commented Nov 26, 2013 at 10:01
You can export a C++/CLI function but it can never be one that uses a managed type as its argument. Like Api^. That doesn't make sense because exported functions are always used by unmanaged code, such code would never now how to pass a managed object. Nor is it necessary at all, you can already use a public ref class from C#, just by adding a reference to the DLL. — Hans Passant
– Hans Passant, Commented Nov 26, 2013 at 10:57

David Heffernan · Accepted Answer · 2013-11-26 16:37:41Z

3

You use __declspec(dllexport) to export a native C++ class. But it sounds like your class is a managed .net ref class. If you wish to export the functionality for both managed clients and unmanaged clients you need to declare two classes. One a managed ref class, and one a native class.

Or perhaps the issue is that you are trying to export a function that has managed parameters with __declspec(dllexport). Again that is not possible.

edited Nov 26, 2013 at 16:37

answered Nov 26, 2013 at 10:10

David Heffernan

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James Ford Over a year ago

Hmm ok. Maybe it's just easier and cleaner if I change this class that I need to pass between functions to a Singleton? That way I will have a global access point to it.

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