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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: Handling transactions?
Date: Tue, 28 Jul 2015 08:45:48 +0200
Organization: cbb software GmbH
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Date: 2015-07-28T08:45:48+02:00
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On Mon, 27 Jul 2015 19:10:09 -0500, Randy Brukardt wrote:

> This is typically used in a block:
> 
>     declare
>          My_Lock : Lock; -- Gets lock.
>     begin
>          -- Do operations needing the lock.
>     end; -- The lock is freed here, no matter how this block is completed.
> 
> I suspect that you could use a similar pattern for transactions (although 
> I've never tried it).

Yes, the way I did it was similar:

   declare
      My_Transaction : Transaction (...);
   begin
      -- Do operations
      Commit (My_Transaction);
   end;

The transaction object has the flag Committed set by Commit. Upon an
exception the flag remains not set and Finalize rolls back. Without an
exception the flag is set and Finalize commits.

The problem with this approach is that you cannot propagate exceptions on
errors from Finalize when commit or rollback fails.

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