[A_Pete]

Hey all,

I am trying to write a new functionObject and adjust it a little bit so that it fits the coding style of the new functionObjects library better.

Now, I am facing a problem since my functionObjectt is supposed to use both features of the writeFiles class and features of the fieldExpression class. These are both class where other functionObjects are derived from.

I don't want to make more than one functionObject out of it, since its usability is very limited and special for my cases. So I was thinking to derive from both writeFiles and fieldExpression classes. The beginnings of my class files look like this:

test.H:

namespace Foam
{
namespace functionObjects
{
class test
:
    public fieldExpression,
    public writeFiles
{ ...

test.C:

namespace Foam
{
namespace functionObjects
{
    defineTypeNameAndDebug(cavEroCDef, 0);
    addToRunTimeSelectionTable(functionObject, cavEroCDef, dictionary);
}
}
...

If I just derive from fieldExpression, my class works fine. If I add the writeFields class as a second base though, I get the following error:

In file included from /local/OpenFOAM/OpenFOAM-4.x/src/OpenFOAM/lnInclude/token.H:49:0,
                 from /local/OpenFOAM/OpenFOAM-4.x/src/OpenFOAM/lnInclude/runTimeSelectionTables.H:35,
                 from /local/OpenFOAM/OpenFOAM-4.x/src/OpenFOAM/lnInclude/functionObject.H:115,
                 from /local/OpenFOAM/OpenFOAM-4.x/src/OpenFOAM/lnInclude/regionFunctionObject.H:42,
                 from /local/OpenFOAM/OpenFOAM-4.x/src/finiteVolume/lnInclude/fvMeshFunctionObject.H:46,
                 from /local/OpenFOAM/OpenFOAM-4.x/src/functionObjects/field/lnInclude/fieldExpression.H:43,
                 from cavEroCDef/cavEroCDef.H:44,
                 from cavEroCDef/cavEroCDef.C:26:
/local/OpenFOAM/OpenFOAM-4.x/src/OpenFOAM/lnInclude/functionObject.H: In instantiation of ‘static Foam::autoPtr<Foam::functionObject> Foam::functionObject::adddictionaryConstructorToTable<functionObjectType>::New(const Foam::word&, const Foam::Time&, const Foam::dictionary&) [with functionObjectType = Foam::functionObjects::cavEroCDef]’:
/local/OpenFOAM/OpenFOAM-4.x/src/OpenFOAM/lnInclude/functionObject.H:164:9:   required from ‘Foam::functionObject::adddictionaryConstructorToTable<functionObjectType>::adddictionaryConstructorToTable(const Foam::word&) [with functionObjectType = Foam::functionObjects::cavEroCDef]’
cavEroCDef/cavEroCDef.C:43:5:   required from here
/local/OpenFOAM/OpenFOAM-4.x/src/OpenFOAM/lnInclude/runTimeSelectionTables.H:72:64: error: ‘Foam::functionObject’ is an ambiguous base of ‘Foam::functionObjects::cavEroCDef’
             return autoPtr<baseType>(new baseType##Type parList);              \
                                                                ^
/local/OpenFOAM/OpenFOAM-4.x/src/OpenFOAM/lnInclude/functionObject.H:164:9: note: in expansion of macro ‘declareRunTimeSelectionTable’
         declareRunTimeSelectionTable
         ^
/local/OpenFOAM/OpenFOAM-4.x/src/OpenFOAM/lnInclude/functionObject.H: In static member function ‘static Foam::autoPtr<Foam::functionObject> Foam::functionObject::adddictionaryConstructorToTable<functionObjectType>::New(const Foam::word&, const Foam::Time&, const Foam::dictionary&) [with functionObjectType = Foam::functionObjects::cavEroCDef]’:
/local/OpenFOAM/OpenFOAM-4.x/src/OpenFOAM/lnInclude/runTimeSelectionTables.H:73:9: warning: control reaches end of non-void function [-Wreturn-type]
         }                                                                      \
         ^
/local/OpenFOAM/OpenFOAM-4.x/src/OpenFOAM/lnInclude/functionObject.H:164:9: note: in expansion of macro ‘declareRunTimeSelectionTable’
         declareRunTimeSelectionTable
         ^
/local/OpenFOAM/OpenFOAM-4.x/wmake/rules/General/transform:8: recipe for target '/local/OpenFOAM/OpenFOAM-4.x/platforms/linux64GccDPInt32Opt/src/functionObjects/cavErosion/cavEroCDef/cavEroCDef.o' failed
make: *** [/local/OpenFOAM/OpenFOAM-4.x/platforms/linux64GccDPInt32Opt/src/functionObjects/cavErosion/cavEroCDef/cavEroCDef.o] Error 1

The output says that the base is ambigous. I think that I have a diamond problem here. I can see that writeFiles and fieldExpression are derived from classes that can be directed back to the functionObject class. It seems like the problem occurs when registering in the runTimeSelectionTable of functionObject.

Does anybody have an idea how to solve this problem? It is really tempting for me to derive from both classes, since I use both their features.

Thanks in advance,
Andreas

[A_Pete]

Consider this problem as solved, since I inherited from writeFields only and got basically all I wanted.