Question

I have two functionally identical header files, one of which produces errors for no discernible reason. I must have done something wrong in creating the new (broken) file, but I can’t figure out what.

My IDE is Xcode. The project is compiled for Objective C++ using Apple LLVM Compiler 4.1, but the section of code in question is all pure C++, no Objective C.

Here’s some code:

NamespaceA.Common.h

#include "../NamespaceB/Common.h"

#include "WorkingClass.h"
#include "BrokenClass.h"

...

../NamespaceB/Common.h

#ifndef NamespaceBCommon
#define NamespaceBCommon

namespace NamespaceB
{
    ...
}

...
#include "Superclass.h"
...

WorkingClass.h

#ifndef NamespaceA_WorkingClass
#define NamespaceA_WorkingClass

namespace NamespaceA
{
    class WorkingClass : public NamespaceB::Superclass
    {
    public:

        WorkingClass();
        ~WorkingClass();
    };
}

#endif

BrokenClass.h

#ifndef NamespaceA_BrokenClass
#define NamespaceA_BrokenClass

// If I don't have this line I get errors. Why??                   !!!!!
// This file is exactly identical to WorkingClass.h 
// as far as I can tell!
//#include NamespaceA.Common.h

namespace NamespaceA
{            
    // Parse Issue: Expected class name                            !!!!!
    // Semantic Issue: Use of undeclared identifier 'NamespaceB'
    class BrokenClass : public NamespaceB::Superclass
    {
    public:

        BrokenClass();
        ~BrokenClass();
    };
}

#endif

Thank you.

Answer 1

I found the problem. WorkingClass.cpp was including NamespaceA.Common.h and not including its own header file, rather than including the common file in the header and then including its own header file in the cpp.

I managed to miss the #include in WorkingClass.cpp because I just assumed it was only including WorkingClass.h and not NamespaceA.Common.h.

So in short:

WorkingClass.h

// Class goes here
// No includes

WorkingClass.cpp

// Notice it does not include WorkingClass.h for whatever reason
#include "NamespaceA.Common.h"

NamespaceA.Common.h

#include "../NamespaceB/Common.h"

#include "WorkingClass.h"
#include "BrokenClass.h"
#include "EveryOtherClass.h" ...

BrokenClass.h

// Class goes here
// No includes

BrokenClass.cpp

#include "BrokenClass.h"
// Oh no! Where's NamespaceA.Common.h?

I’m not a big fan of this include scheme, but I’ll live with it since it’s a large project that I don’t want to make sweeping changes to.