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From: Georg Bauhaus <sb463ba@l1-hrz.uni-duisburg.de>
Newsgroups: comp.lang.ada
Subject: Re: Mneson announcement and help request
Date: Wed, 2 Jun 2004 11:41:33 +0000 (UTC)
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Date: 2004-06-02T11:41:33+00:00
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Georg Bauhaus <sb463ba@l1-hrz.uni-duisburg.de> wrote:
: Marius Amado Alves <amado.alves@netcabo.pt> wrote:
: :> In general, I hate to see code that uses exceptions for normal control flow
: :> processing. It certainly appears to
: :> me that your code that makes use of the various For_Each_XXX type procedures
: :> uses an exception
: :> raise to terminate the search when "done".
: : 
: : Yes, that is a controversial style. Some like it, some don't. Note the 
: : planned Ada standard containers are in this style.
: 
: How about this, which doesn't need exceptions:

[...]
OK in my example you need to know where to stop before traversal.
However, there is a third variation, only slightly different from
the one Jeffrey Carter mentioned, and it still doesn't need
exceptions with AI302.

   generic
      with procedure Process(Pointee: Sets_of_T.Cursor);
      with function Stop(Pointee: Sets_of_T.Cursor) return Boolean;
      --  terminate Process-ing when Stop says so

   procedure Traverse (container: Sets_of_T.Set);

The loop is changed to

      while not Stop(current) loop  -- the change
         process(current);
	 next(current);  -- moving the cursor was missing before :-(
      end loop;


-- Georg