Refer to field of a struct using input variable

Hello everyone,

Is there a way in matlab to refer to a field of a struct or (any variable) using an input variable ?

Consider I have to functions: Main and Change_Color; and there is a variable app.LampVS.Color that I want to set its value using Change_Color, is there a way to refer to LampVS using a handle for example :

• Please not that the variable app can be accessed by both functions

 function main(app)
            Change_Lamp(app,'LampVS','green');
 end

 function Change_Lamp(app,Lamp,Color)
            switch Color
                case 'red'
                    Color_Matrix = [1.00 0.00 0.00];
                case 'green'
                    Color_Matrix = [0.04 1.00 0.04];
                case 'orange'
                    Color_Matrix = [1.00 0.65 0.00];
            end

            app. *(@Lamp)?*.Color = Color_Matrix;

   end