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From: jjjensen@cybernet.dk (Jens Jakob Jensen)
Subject: Re: Q. on Automatic Package Finalization
Date: 1996/09/25
Message-ID: <oBISyExFEStK086yn@cybernet.dk>#1/1
X-Deja-AN: 185142391
references: <523tt4INNlu7@snoopy.cis.ohio-state.edu>
 <dewar.843529239@schonberg>
content-type: text/plain; charset=ISO-8859-1
organization: Ozwix Data
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newsgroups: comp.lang.ada
Date: 1996-09-25T00:00:00+00:00
List-Id: <comp.lang.ada>


In article <324837B8.2361@watson.ibm.com>,
"Norman H. Cohen" <ncohen@watson.ibm.com> wrote:
[snippety-snip]
>The feature we considered during the 9X design, by the way, was simple,
>succinct, and intuitive:  Everywhere Ada allows
>
>   begin
>      ...
>   exception
>      ...
>   end
>
>we would have allowed
>
>   begin
>      ...
>   exception
>      ...
>   at end
>      < sequence of frame finalization statements >
>   end
>
>The semantics would have been the same as the 
>
>   try { ... } catch { ... } finally { ... }
>
>construct in Java or
>
>   TRY
>      TRY
>         ...
>      EXCEPT
>         ...
>      END
>   FINALLY
>      ...
>   END
>
>in Modula-3:  The frame-finalization statements get executed both after
>normal exit from a frame and after execution of an exception handler for
>the frame.

Does this include leaving the frame by return and abort ? I haven't looked
enough into these languages, I'm afraid.

If not, one could do something like:

procedure P is
   ...
   procedure Finalize is
      ...
   end Finalize;
   ...
begin
   ...
   Finalize;
exception
   when ... =>
      ...
      Finalize;
   when others =>
      Finalize;
      raise;
end P;

You have to be really sloppy to miss calling "Finalize" when adding an
exception handler later on. But it _will_ happen, of course...

>Norman H. Cohen
>mailto:ncohen@watson.ibm.com
>http://www.research.ibm.com/people/n/ncohen

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