Re: A few questions

[Simon Wright <simon@pushface.org>]

"Randy Brukardt" <randy@rrsoftware.com> writes:

> <briot.emmanuel@gmail.com> wrote in message 
> news:aa0cf839-651e-494d-a826-c2ce31a7afd3@googlegroups.com...
>>> The "of" form is for iterating over an array or a container whose
>>> type has the Default_Iterator aspect (which gives the iterator to
>>> use).
>>
>> The main drawback, though, is that you then get a Cursor, not an
>> Element, so you still need to call the functions Element or Reference
>> to get to the actual element. This is slightly less convenient
>> (syntax-wise).
>
> Sure, but not in a case like the OP's, where the "cursor" is the
> actual data and there is no element. In that case, "of" is just
> overkill.

There's one problem for Times; how to determine when to end the loop if
the cursor is the actual data?

I ended up with

   type Cursor (Valid : Boolean := True) is record
      case Valid is
         when True =>
            Date : Ada.Calendar.Time;
         when False =>
            null;
      end case;
   end record;

where both First and Next set Valid to False if the iteration has ended.

I spent a lot too much time without giving Valid a default value; there
is an assignment, but it's hidden inside the generated code, so at the
end of the loop the discriminant changes ...

I think this may be related to the way that F552A00_Prime_Numbers
doesn't support an upper bound of 2; the loop terminates when Is_Prime
returns false, and of course 2 + 1 = 3 which .. Is_Prime.