Question

I have a native C++ library (let’s call it CoreLib.dll) and it exposes two classes:

• Core.h
• Atom.h

I have a CLI/C++ wrapper (let’s call it CoreWrapper.dll) that allows .NET projects to instantiate Core and Atom objects:

• CoreDotNet.h
• AtomDotNet.h (includes Atom.h and CoreDotNet.h)

When I compile the CoreWrapper, only CoreDotNet.h gets compiled and AtomDotNet.h gets ignored. If I want to compile AtomDotNet.h, then I must include it in CoreDotNet.h, but that causes a compiler error in CoreDotNet.h:

error C2011: 'CoreWrapperNS::CoreDotNet' : 'class' type redefinition

Here is some basic code that represents what I’m doing:

#pragma once // <-- should protect from class type redefinition
#include "Core.h"
//#include "AtomDotNet.h" // uncommenting causes compiler error C2011

using namespace CoreNS;

namespace CoreWrapperNS
{
    public ref class CoreDotNet
    {
    public:
        // Allows users to instantiate a core object
        CoreDotNet();
        CoreDotnet(Core* core);
        //... destructor follows
    };
}

Here is the AtomDotNet.h file:

#pragma once // <-- should protect from class type redefinition
#include "Atom.h"
#include "CoreDotNet.h"

namespace CoreWrapperNS
{
    public ref class AtomDotNet
    {
    private:
        Atom*       _atom;
        CoreDotNet^ _core;
    public:
        AtomDotNet()
        {
            // The atom allows users to instantiate an atom with a core
            // and to get a reference to the core of the given atom.
            Core* core = new Core();
            _atom = new Atom(core);
            _core = gcnew CoreDotNet(core);
        }

        inline CoreDotNet^ GetCore(){return _core;}
        //... destructor follows
    };
}

The CoreWrapper project has a reference to the CoreLib project. I’ve seen some posts around the “Internets” about CLI/C++ wrappers getting the above mentioned compiler error because they reference the C++ project AND they include the header file, but I didn’t have that problem until I added a second class (i.e. the AtomDotNet class) to the wrapper library and I tried to compile it. Any ideas on what might be happening here?

Answer 1

Merely writing your code in header files doesn’t cause it to be included in the project.

You need to add .cpp files to the project, and #include the headers.