From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-0.3 required=5.0 tests=BAYES_00, REPLYTO_WITHOUT_TO_CC autolearn=no autolearn_force=no version=3.4.4 Path: eternal-september.org!reader01.eternal-september.org!reader02.eternal-september.org!news.eternal-september.org!mx02.eternal-september.org!feeder.eternal-september.org!aioe.org!.POSTED!not-for-mail From: "Dmitry A. Kazakov" Newsgroups: comp.lang.ada Subject: Re: Running a preprocessor from GPS? Date: Thu, 30 Jul 2015 15:30:42 +0200 Organization: cbb software GmbH Message-ID: References: <2df4698f-4c8e-457c-822d-209cb2f8ab5e@googlegroups.com> <014427b1-ff7a-4a69-82e6-0330af77ed96@googlegroups.com> <91f88d79-197c-419f-84a8-908e05967a2c@googlegroups.com> <135c2b00-d13c-4f5d-a586-8aca442d363b@googlegroups.com> <947bb170-91aa-4e99-810e-7154be9bae6a@googlegroups.com> Reply-To: mailbox@dmitry-kazakov.de NNTP-Posting-Host: ChlmA4XFxcJoDoqGdDSflw.user.speranza.aioe.org Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit X-Complaints-To: abuse@aioe.org User-Agent: 40tude_Dialog/2.0.15.1 X-Notice: Filtered by postfilter v. 0.8.2 Xref: news.eternal-september.org comp.lang.ada:27206 Date: 2015-07-30T15:30:42+02:00 List-Id: On Thu, 30 Jul 2015 06:00:11 -0700 (PDT), EGarrulo wrote: > On Thursday, July 30, 2015 at 1:22:36 PM UTC+2, Niklas Holsti wrote: >> On 15-07-30 11:45 , EGarrulo wrote: >> > Exceptions in Ada cannot ... be chained >> >> I'm not sure what you mean by "chained", but an Ada exception handler >> can either raise another exception, or re-raise the same exception, for >> handling at higher levels. > > By "chained", I mean that a failure in an operation can > cause a failure in the calling operation, and so on. Let's > imagine that the initialization of an application relies > on reading a configuration file. If the syntax of the > configuration file is not correct, then the routine that > reads it will raise an exception, but this exception would > be too low-level to be meaningful for the user. Therefore, > it makes sense to chain this exception to another higher- > level exception that explains what the application was > trying to do. To the end user, this will appear as a chain > of exceptions: > > - INITIALIZATION_ERROR: The application failed to initialize; > - CONFIGURATION_ERROR: The configuration failed; > - BAD_FORMAT: The configuration file isn't formatted correctly; > - SYNTAX_ERROR: The value of LEVEL is not of the expected type. > > Basically, each exception in the chain answers the > question "why?" Now, if you report only one of those > exceptions, then you lose context. This is why you should > be able to chain exceptions. Of course, you could achieve > a similar result by concatenating messages, but this way > you would be performing manually what the language should > have performed automatically. exception when Error : Chain_Error => raise Chain_Error with "Worse than " & Exception_Message (Error); end; -- Regards, Dmitry A. Kazakov http://www.dmitry-kazakov.de