Re: No Go To's Forever!

[tmoran@bix.com]

>Of course you could argue that it is easier to find your refined
>superior form from my syntactic expression with nested loops
>than from the original with a goto, and that would be an
>interesting argument to make.

  For example:
> following sorting algorithm:
>
>   <<Do_It_Again>>
>      for J in 1 .. N - 1 loop
>         if D (J) < D (J + 1) then
>            Swap (D (J), D (J + 1));
>            goto Do_It_Again;
>         end if;
>      end loop;

re-written with While instead of goto is

      J := D'first;
      while J < D'last loop
         if D (J) >= D (J + 1) then   -- sorted so far
            J := J+1;                 -- continue
         else
            Swap (D (J), D (J + 1));  -- out of order, move item
            J := D'first;             -- and start over
         end if;
      end loop;

which practically makes you trip over an obvious improvement in the
algorithm to

      J := D'first;
      while J < D'last loop
         if D (J) >= D (J + 1) then   -- sorted so far
            J := J+1;                 -- continue
         else
            Swap (D (J), D (J + 1));  -- out of order, move item
            if J > D'first then       -- and start checking at
              J := J-1;               -- the first changed spot
            end if;
         end if;
      end loop;