Evil Class Exporting

[Zaei]

Well, this is getting annoying. I have something along these lines:

class __declspec(dllexport) IMesh : public IObject, IThinker, IRenderable
{
   ...
protected:
   CSmartPtr<IVertexBuffer> myVB;
   ...
};

On every compile, I get a warning that says something like this:

'myVB': 'CSmartPtr<IVertexBuffer>' must have dll-interface to be used by clients of 'IMesh'

MSDN says that the base class has to be defined with __declspec(dllexport). So, i spent a while adding __declspec(dllexport) to every class that has anything to do with anything. I get the same thing. Am I missing something, or doing something totally wrong?

Z.

[parksie]

You need to explicitly instantiate the template:

template class CSmartPtr<IVertexBuffer>;

...or something, can't quite remember.

[Zaei]

Yep. I figured that out this afternoon. Now I get errors that say that I am redefining the class "CSmartPtr<IVertexBuffer>". Where should I put the explicit instantiation?

BTW, its class a<b> {};, or template<> class a<b> {};.

Z.

[Zaei]

Well, I got it going...
In the DLL:

template class __declspec(dllexport) CSmartPtr<IVertexBuffer>;

and in the Exe:

extern template class __declspec(dllimport) CSmartPtr<IVertexBuffer>;

This is apparently a really obscure problem. You can also use it to export classes that use an STL vector from a DLL as well:

template class __declspec(dllexport) std::vector<int>;

From what I read, this is the only class that you can export, as many of others contain nested classes, that cannot be instantiated like that, and so, cant be exported.

Z.

[kf4oij]

C must have been invented to lower the population of the earth.

Although I feal I have reached a point where I MUST change from VB to C++ I don't want to. I was all jazzed about it, so I could take advantage of all of C++'s capabilities like subclassign, and virtual functions, and all those other things, the developers of VB had mercy and decided not to include, and then I saw your code snippet. I have used C++ before. And I know that with enough practice, reading that code will be like reading a book (just like VB code) but it might as well be Chineese right now.

Oh well, don't mind my rambling,

Joey

[Zaei]

Dont worry about it. Its some of the more advanced stuff (if parksie AND kedaman couldnt help... =) that you wont get to for quite a while.

Z.