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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: potential Ada feature - comments?
Date: Tue, 10 Sep 2019 21:13:13 +0200
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Xref: reader01.eternal-september.org comp.lang.ada:57127
Date: 2019-09-10T21:13:13+02:00
List-Id: <comp.lang.ada>

On 2019-09-10 19:52, Matt Borchers wrote:
> I often find myself writing the same code fragment in exception handlers.  That is, I catch and handle the specific exceptions and the cleanup code for the subprogram is identical.  I know that I can (and do) write a cleanup routine to handle this, but even so, the call to the cleanup routine must still be added to every exception case in the handler.
> 
> procedure SUBPROGRAM is
>     procedure CLEANUP is
>     begin
>        --free resources
>        ...
>     end CLEANUP;
> begin
>     --acquire resources
>     ...
> exception
>     when X =>
>        --something for X
>        cleanup;
>     when Y =>
>        --something for Y
>        cleanup;
>     when Z =>
>        --something for Z
>        cleanup;
>     when others =>
>        --general case
>        cleanup;
> end SUBPROGRAM;

I would rather:

    procedure SUBPROGRAM is
    begin
         --acquire resources
       begin
         ...
         -- keep resources if all OK????
       exception
          when X =>
             --something for X
             raise;
          when Y =>
             --something for Y
             raise;
          when Z =>
             --something for Z
             raise;
          when others =>
             --general case
             raise;
       end;
    exception
       when others =>
          --free resources
    end SUBPROGRAM;

But my preferred method is to use a controlled object with freeing the 
resource inside finalization.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de