Re: Thought this was funny

[Georg Bauhaus <sb463ba@l1-hrz.uni-duisburg.de>]

Robert I. Eachus <rieachus@comcast.net> wrote:
: Stephane Richard wrote:
: 
:> I'm canadian and that code made me chuckle too ;-). The programmer much have
:> read how to handle the enumeration type first, then read about the Boolean
:> type being an enumeration of True and False maybe? ;-).
: 
: No, he must have been taught that your program design should allow for 
: changes in requirements.  He was prepared for another value being added 
: to Boolean. ;-)

Or he is just a careful programmer, who knows GNAT, case statements,
and Unchecked_Conversion :-)

with Unchecked_Conversion;
with Ada.Text_IO; use Ada;

procedure test is

   type This_Or_That is (This, That);
   for This_Or_That use (That => 17, This => 4);
   for This_Or_That'Size use 8;

   type My_Truth is new Boolean;
   for My_Truth'Size use 8;



   function from_This_Or_That is
      new Unchecked_Conversion(This_Or_That, My_Truth);

begin

   if from_This_Or_That(This) then
      Text_IO.put_line("Y");
   else
      Text_IO.put_line("N");
   end if;


   case from_This_Or_That(This) is
      when True =>
         Text_IO.put_line("Y");

      when False =>
         Text_IO.put_line("N");
   end case;

end test;


$ ./test
Y

raised CONSTRAINT_ERROR : test.adb:27 invalid data


Georg