[Krischan]

Hey everyone,
I'm currently working on a solver and wrote some functions I would like to put in a second .C file (not the main solver code).

I wrote a file helperFunctions.H

#include "fvCFD.H"

namespace Foam {
template<class Type>
void printField(OSstream& output, const GeometricField<Type, fvPatchField, volMesh>& vf);
}
}

And have the definition of that function in helperFunctions.C

#include "helperFunctions.H"
namespace Foam {
template<class Type>
void printField(OSstream& output, const GeometricField<Type, fvPatchField, volMesh>& vf) {
    forAll (vf.internalField(),icell) {
        output << vf.internalField()[icell] << " ";
    }
}
}

I also added helperFunctions.C to Make/files
My main solver as well as helperFunctions.C compile fine, but when it comes to linking I get the error message

 undefined reference to `void Foam::printField<double>(Foam::OSstream&, Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&)'

Obviously I'm doing something wrong here, but I don't see the reason, so any help is appreciated.

Thanks,
Christian

[Krischan]

Okay, after reading my Stroustrup and the C++ FAQ I got it.
It's because of how templates work... Time to refresh my C++ Skills, I guess