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=-1.9 required=5.0 tests=BAYES_00 autolearn=unavailable autolearn_force=no version=3.4.4 Path: eternal-september.org!reader01.eternal-september.org!reader02.eternal-september.org!feeder.eternal-september.org!gandalf.srv.welterde.de!news.jacob-sparre.dk!franka.jacob-sparre.dk!pnx.dk!.POSTED.rrsoftware.com!not-for-mail From: "Randy Brukardt" Newsgroups: comp.lang.ada Subject: Re: Interesting article on ARG work Date: Thu, 5 Apr 2018 17:18:57 -0500 Organization: JSA Research & Innovation Message-ID: References: <1b44444f-c1b3-414e-84fb-8798961487c3@googlegroups.com> <62ee0aac-49da-4925-b9aa-a16695b3fc45@googlegroups.com> <9879872e-c18a-4667-afe5-41ce0f54559f@googlegroups.com> Injection-Date: Thu, 5 Apr 2018 22:18:58 -0000 (UTC) Injection-Info: franka.jacob-sparre.dk; posting-host="rrsoftware.com:24.196.82.226"; logging-data="29796"; mail-complaints-to="news@jacob-sparre.dk" X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 6.00.2900.5931 X-RFC2646: Format=Flowed; Response X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.7246 Xref: reader02.eternal-september.org comp.lang.ada:51348 Date: 2018-04-05T17:18:57-05:00 List-Id: "Dmitry A. Kazakov" wrote in message news:pa4ip3$1ton$1@gioia.aioe.org... > On 05/04/2018 00:30, Randy Brukardt wrote: > >> There is a much more general proposal for Ada 2020 called "ghost code" - >> a >> silly name for code and declarations intended only to be used by >> assertions. >> (The idea being that if it is marked and enforced as such, it can be >> removed >> when the Assertion_Policy is Ignore.) >> >> Using that (which may or may not make it into Ada 2020 -- we haven't yet >> discussed it at a meeting), one could use a ghost function for this >> purpose: >> >> function My_Assertion (...) return Boolean is >> (if Condition then raise Assertion_Error with Message else >> True) >> with Ghost; >> >> pragma Assert (My_Assertion (...)); >> >> (Note: The "..." here is any objects that Condition needs to be >> evaluated.) > > Assertion code is quite useless from my point of view, but what about > debugging code? It is quite tedious to comment it in and out all the time > (and with/use clauses required for it). My assumption has always been that Ghost code could be used for that as well, but since it's more of an idea than a proposal, it's hard to say anything definitive. If you used Janus/Ada, you'd have a built-in solution for that (sadly, incompatible with Ada 2020): the @ conditional compilation marker. It is interpreted as either "--" or " " depending on a compilation flag, so it can easily add or remove anything. We originally invented it to deal with debugging/assertion code in the Janus/Ada compiler; probably about 25% of the code in Janus/Ada is marked that way. Since it is lexical, it can comment out anything, including declarations, pragmas, and with clauses. In programs intended to be portable, I just use static Boolean flags for debugging code. Any compiler with decent dead code elimination (which would be about all of them) will get rid of most/all of the code that way. But that doesn't work on pragmas, context clauses, or declarations, so it isn't quite as through as @. (With Janus/Ada, which does dead subprogram elimination during binding, including for tagged type primitives, the difference isn't that substantial unless large data declarations are involved.) Randy.