Re: Curious Question

[nobody@REPLAY.COM (Anonymous)]

On 4 Dec 1997 20:53:06 GMT, car@swl.msd.ray.com (Chad Reichenbach
{81726}) wrote:

> I have a question I can'f figure out.  If I have the following code:
> 
>   type My_Type is (obj1, obj2 obj3, obj4, obj5, obj6);
>   subtype My_Subtype is My_Type range obj1 .. obj4;
> 
> My question is, I need a new subtype that ranges from obj4 to obj1.
> Will the declaration
> 
>   subtype Second_Subtype is My_Subtype
>           range My_Subtype'last .. My_Subtype'first
> 
> do that?  If not is there a way to do it without defining a new
> enumeration?
> 
> The type would be used in a loop that loops through the enumeration
> objects using S'succ(S).
> 

Not necessary:

   for S in reverse My_Subtype loop

The first time through the loop, S = My_Subtype'Last; the next time, S =
My_Subtype'Pred (My_Subtype'Last); ...; the last time, S =
My_Subtype"First.

If you need to manually work through the loop, use 'Pred instead of
'Succ:

   S := My_Subtype'Last;

   loop
      -- Do stuff with S

      exit when S = My_Subtype'First;

      S := My_Subtype'Pred (S);
   end loop;

Jeff Carter  PGP:1024/440FBE21
My real e-mail address: ( carter @ innocon . com )
"We burst our pimples at you."
Monty Python & the Holy Grail

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