[fpc-pascal] Case in Record

[Jürgen Hestermann]

> AFAIK there has to be some fixed part before the variant, e. g.
> TFigure = record
>     name: string;
>     case TShapeList of
>       Rectangle: (Height, Width: Real);
>       Triangle: (Side1, Side2, Angle: Real);
>       Circle: (Radius: Real);
>       Ellipse, Other: ();
>   end;
> The program could then determine from the contents of the "name" field
> which variant is used in a certain instance. 

How would that work? "name" is just a string which you can assign an 
arbitrary value to. The compiler cannot store additional information in it.

The detection of the correct variant is completely up to the programmer. 
There is no help by the compiler.

Therefore, there is absolutly no difference between

TFigure = record
           X : TShapeList;
           case TShapeList of
              Rectangle: (Height, Width: Real);
              Triangle: (Side1, Side2, Angle: Real);
              Circle: (Radius: Real);
              Ellipse, Other: ();
              end;

and

TFigure = record
           case X : TShapeList of
              Rectangle: (Height, Width: Real);
              Triangle: (Side1, Side2, Angle: Real);
              Circle: (Radius: Real);
              Ellipse, Other: ();
              end;

It ends up in the same record and also the programmer does not see any 
difference. He can store whatever he wants in X in both cases. It has no 
influences on the variants.