Columns

- The Columns::is_uda() method allows identification of UDA attributes.

src/columns/Column.h

@@ -50,6 +50,7 @@ public:
   std::string label () const                  { return _label;      }
   std::string type () const                   { return _type;       }
   bool modifiable () const                    { return _modifiable; }
+  bool is_uda () const                        { return false;       }
   std::vector <std::string> styles () const   { return _styles;     }
   std::vector <std::string> examples () const { return _examples;   }