PyObject* Table::columns() const{
     Ilwis::ITable tbl = this->ptr()->as<Ilwis::Table>();
     PyObject* list = newPyTuple(tbl->columnCount());
     for(int i = 0; i < tbl->columnCount(); i++){
         Ilwis::ColumnDefinition coldef = tbl->columndefinition(i);
         if (!setTupleItem(list, i, PyUnicodeFromString(coldef.name().toStdString().data())))
             throw Ilwis::ErrorObject(QString("internal conversion error while trying to add '%1' to list of columns").arg(tbl->columndefinition(i).name()));
     }
     return list;
 }
 std::vector<std::string> Table::columns() const{
     Ilwis::ITable tbl = this->ptr()->as<Ilwis::Table>();
     std::vector<std::string> vector;
     for(int i = 0; i < tbl->columnCount(); i++){
         Ilwis::ColumnDefinition coldef = tbl->columndefinition(i);
         vector.push_back( coldef.name().toStdString() );
         //if (!setTupleItem(list, i, PyUnicodeFromString(coldef.name().toStdString().data())))
             //throw Ilwis::ErrorObject(QString("internal conversion error while trying to add '%1' to list of columns").arg(tbl->columndefinition(i).name()));
     }
     return vector;
 }