[netinstall] Introduce constexpr names for columns and roles

src/modules/netinstall/PackageModel.cpp

@@ -117,7 +117,7 @@ PackageModel::data( const QModelIndex& index, int role ) const
     }
 
     PackageTreeItem* item = static_cast< PackageTreeItem* >( index.internalPointer() );
-    if ( index.column() == 0 && role == Qt::CheckStateRole )
+    if ( index.column() == NameColumn && role == Qt::CheckStateRole )
     {
         return item->isSelected();
     }
@@ -156,7 +156,7 @@ PackageModel::flags( const QModelIndex& index ) const
     {
         return Qt::ItemFlags();
     }
-    if ( index.column() == 0 )
+    if ( index.column() == NameColumn )
     {
         return Qt::ItemIsUserCheckable | QAbstractItemModel::flags( index );
     }
@@ -168,7 +168,7 @@ PackageModel::headerData( int section, Qt::Orientation orientation, int role ) c
 {
     if ( orientation == Qt::Horizontal && role == Qt::DisplayRole )
     {
-        return ( section == 0 ) ? tr( "Name" ) : tr( "Description" );
+        return ( section == NameColumn ) ? tr( "Name" ) : tr( "Description" );
     }
     return QVariant();
 }

src/modules/netinstall/PackageModel.h

@@ -39,6 +39,16 @@ class PackageModel : public QAbstractItemModel
 public:
     using PackageItemDataList = QList< PackageTreeItem::ItemData >;
 
+    // Names for columns (unused in the code)
+    static constexpr const int NameColumn = 0;
+    static constexpr const int DescriptionColumn = 1;
+
+    /* The only interesting roles are DisplayRole (with text depending
+     * on the column, and MetaExpandRole which tells if an index
+     * should be initially expanded.
+     */
+    static constexpr const int MetaExpandRole = Qt::UserRole + 1;
+
     explicit PackageModel( const YAML::Node& data, QObject* parent = nullptr );
     ~PackageModel() override;