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 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 103376,330ec86e1824a689 X-Google-Attributes: gid103376,public X-Google-ArrivalTime: 2002-08-29 03:48:59 PST Path: archiver1.google.com!news1.google.com!newsfeed.stanford.edu!news.tele.dk!small.news.tele.dk!193.174.75.178!news-fra1.dfn.de!fu-berlin.de!uni-berlin.de!b984e.pppool.DE!not-for-mail From: Dmitry A.Kazakov Newsgroups: comp.lang.ada Subject: Re: Run-Time Type Assignment Date: Fri, 30 Aug 2002 00:55:51 +0200 Message-ID: References: Reply-To: mailbox@dmitry-kazakov.de NNTP-Posting-Host: b984e.pppool.de (213.7.152.78) Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7Bit X-Trace: fu-berlin.de 1030618137 53863287 213.7.152.78 (16 [77047]) User-Agent: KNode/0.4 Xref: archiver1.google.com comp.lang.ada:28546 Date: 2002-08-30T00:55:51+02:00 List-Id: Lutz Donnerhacke wrote: > * Robert A Duff wrote: >>Kilgallen@SpamCop.net (Larry Kilgallen) writes: >>> What is a downward closure ? >> >>The ability to pass a procedure as a parameter to a procedure. >>The "downward" means the closure is passed "down" from caller to >>callee. This is more restrictive than the "full closures" which are >>found in Lisp and many other languages of that ilk; a full closure may >>be *returned* from a procedure, and may be assigned into a variable. >> >>GNAT supports downward closures via the 'Unrestricted_Access attribute, >>but that's not Ada (unfortunately). >> >>In Pascal, downward closures are very useful for making iterators and >>other user-defined control structures. > > In Ada you use generics for this. It is a nasty work-around. IMO Ada should have true subroutine types [restricted of course]. -- Regards, Dmitry Kazakov www.dmitry-kazakov.de