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=-1.3 required=5.0 tests=BAYES_00,INVALID_MSGID autolearn=no autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 103376,1e4280c6ade7eb23 X-Google-Attributes: gid103376,public From: Brian Rogoff Subject: Re: Exception types? Date: 1998/06/15 Message-ID: #1/1 X-Deja-AN: 362871329 References: <3584F47B.3ADF7442@elca-matrix.ch> To: Mats Weber Content-Type: TEXT/PLAIN; charset=US-ASCII X-Trace: 897929280 10129 bpr 206.184.139.132 Mime-Version: 1.0 Newsgroups: comp.lang.ada Date: 1998-06-15T00:00:00+00:00 List-Id: On Mon, 15 Jun 1998, Mats Weber wrote: > Brian Rogoff wrote: > > It isn't really a workaround, as you haven't really parameterized the > > package by an exception, and you can't pass that package as a generic > > formal package parameter. Mats workaround involved passing a success/failure > > function (an exception "wrapper"), which is a little better in the > > particular case I'm interested in. > > This is not true, or at least inaccurate (I don't know what you mean by "a > success/failure function" or an exception "wrapper"). On page 9 of your thesis, you discuss one Ada 83 workaround to the lack of exception types, that is passing around a function (End_Of_File) and assuming that it is checked at places where an exception might be raised. That is what I meant by "your workaround", not your actual language extension proposals. > My proposal is to add parameters to exceptions, as in Modula-3 (and in Ada 95, > with the IMO ridiculous limitation to strings of 200 characters). > > In one of the 9X Mapping documents, there was an extension to Ada's exceptions > that essentially made them part of the type system and you could derive them > much as you can derive types, thus creating a hierarchy of exceptions. > This would be very useful, and would bring one more surly language construct under the dominance of the package system. -- Brian > > [...] but I was wondering what the thinking was > > behind not having typed exceptions to begin with in Ada 83. I imagine the > > reason for not having them in Ada 95 could be upward compatibility. > > The proposal was in the mapping, but was removed. Maybe someone who > participated actively in the language design can tell us why ? > >