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=ham autolearn_force=no version=3.4.4 X-Google-Thread: 103376,703c4f68db81387d X-Google-Thread: 109fba,703c4f68db81387d X-Google-Thread: 115aec,703c4f68db81387d X-Google-Thread: f43e6,703c4f68db81387d X-Google-Attributes: gid103376,gid109fba,gid115aec,gidf43e6,public X-Google-Language: ENGLISH,ASCII Path: g2news1.google.com!news1.google.com!proxad.net!proxad.net!62.253.162.218.MISMATCH!news-in.ntli.net!newsrout1-win.ntli.net!ntli.net!newspeer1-win.ntli.net!newsfe1-gui.ntli.net.POSTED!53ab2750!not-for-mail From: "Dr. Adrian Wrigley" Subject: Re: [OT] Re: Teaching new tricks to an old dog (C++ -->Ada) User-Agent: Pan/0.14.2 (This is not a psychotic episode. It's a cleansing moment of clarity.) Message-Id: Newsgroups: comp.lang.ada,comp.lang.c++,comp.realtime,comp.software-eng References: <4229bad9$0$1019$afc38c87@news.optusnet.com.au> <1110032222.447846.167060@g14g2000cwa.googlegroups.com> <871xau9nlh.fsf@insalien.org> <3SjWd.103128$Vf.3969241@news000.worldonline.dk> <87r7iu85lf.fsf@insalien.org> <1110052142.832650@athnrd02> <42309456$1@news.broadpark.no> <4232ab3a$0$26547$9b4e6d93@newsread4.arcor-online.net> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit Date: Mon, 14 Mar 2005 17:16:44 GMT NNTP-Posting-Host: 81.100.88.147 X-Complaints-To: http://www.ntlworld.com/netreport X-Trace: newsfe1-gui.ntli.net 1110820604 81.100.88.147 (Mon, 14 Mar 2005 17:16:44 GMT) NNTP-Posting-Date: Mon, 14 Mar 2005 17:16:44 GMT Organization: ntl Cablemodem News Service Xref: g2news1.google.com comp.lang.ada:9373 comp.lang.c++:45589 comp.realtime:1456 comp.software-eng:5022 Date: 2005-03-14T17:16:44+00:00 List-Id: On Mon, 14 Mar 2005 17:06:10 +0100, Falk Tannh�user wrote: > Alternatively, if there is no natural definition for a general-purpose > operator< for the key type in question, it is possible to create a > comparison functor and to instantiate the container with it as > supplementary template parameter. the problem as I suggested in my previous post is that you have to pass in the comparison operator or hash function down the tree of template/generic instantiation, (composing them along the way) if you want to use maps/hashes. If the necessary functions are not passed in and built up, you can't instantiate the map/hash. This means that you can't write an implementation of a template/generic function using a map/hash without changing some/all the implementations and interfaces up the instantiation tree (am I right?). Obviously this may not be possible, for example in large a multi-team or multi language project. If you changed from a map to a hash, you'd have to change all the interfaces to pass the hashing function instead or as well as the comparison operator. In Ada, a private (nonlimited) generic formal type guarantees an equality operation and assignment is defined for the type. These are the only logical requirements for an associative array. I guess an efficient hash/map library could be written for private nonlimited generic formals, but neither std::map nor hashed maps meet this less restrictive requirement. Put another way, neither language has minimally restrictive associative arrays in their (or their standard library) specification. -- Adrian