Re: (Num_Types.Mod_4 range 1..8) ------->why not (1..8)?

[Petter <petter_fryklund@hotmail.com>]

For scalar types Checked_Conversion is a good idea:

generic
   type Source is (<>);
   type Target is (<>);

function Checked_Conversion (S : Source) return Target;

with Ada.Unchecked_Conversion;
function Checked_Conversion (S : Source) return Target is
   function "+" is new Ada.Unchecked_Conversion (Source => Source,
                                                 Target => Target);
begin
   declare
      Return_Value : Target := + S;
   begin
      if not Return_Value'Valid then
         raise Constraint_Error;
      end if;
      return Return_Value;
   end;
end Checked_Conversion;