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,e5eb8ca5dcea2827 X-Google-Attributes: gid103376,public From: Laurent Guerby Subject: Re: Ada OO Mechanism Date: 1999/05/28 Message-ID: <86k8ttqgia.fsf@ppp-159-70.villette.club-internet.fr>#1/1 X-Deja-AN: 483173068 References: <7i05aq$rgl$1@news.orbitworld.net> <7i17gj$1u1k@news2.newsguy.com> <7iems7$1vm@news2.newsguy.com> <86iu9fhawg.fsf@ppp-101-91.villette.club-internet.fr> X-Trace: front1.grolier.fr 927910520 23485 195.36.159.70 (28 May 1999 16:55:20 GMT) Organization: Club-Internet (France) NNTP-Posting-Date: 28 May 1999 16:55:20 GMT Newsgroups: comp.lang.ada Date: 1999-05-28T16:55:20+00:00 List-Id: Hyman Rosen writes: > No, you can not. There are tricks that can accomplish the test, but > they are tricks, not basic language features. The C++ approach to > generics is "if it compiles, it works". If I understand the rest of your posting, the C++ approach is "if it links, it works". You have to wait the linker to complain about mangled symbols not to be there to have the pleasure of trying to find out where you messed up your template ;-). > Instead of restricting a parameter to be of a certain type, you just > write the template as if the parameter has that type. It may be that > a different type will support the operations equally well, in which > case there is no reason to prevent the template from working. I > understand that this is unpleasant for many people who want to be > able to say and see exactly what's going on with the code. Strange, I would say that in Ada you doesn't have to know "exactly what's going on with the code" inside your generic to use and compile things, whereas in C++ you have to see the template code to see if your parameters will work. That's breaking some abstraction. In Ada: "if it compiles against the spec it works, regardless of the implementation". This favour distributed team work, properly abstracted generic specs and so ease build large reliable stuff. > In C++ as well. In C++, you use a template parameter - > > template struct Array { T a[N]; } > Array ai; > Array ad; > > Ada is somewhat ahead here, though, because (if I'm not mistaken) > in Ada all the discrminated forms are the same type while in C++ > they're not (i.e., in C++, Array and Array are > completely unrelated). Interesting ;-). Also Ada programmers tend to have big generic contracts (read lots of template arguments), I think the C++ notation will tend to be cumbersome if one complex template instanciation type is used a lot (well, you can #define then ;-). > For objects at file scope in a single compilation unit (a file), > constructors are called in top-to-bottom order. For static objects > within a function, constructors are called the first time the flow > of control passes through the definition. Order of initialization > across compilation units is unspecified. That was my point, unless you put everyting in a big C++ source file you cannot build statically (at elaboration time in the Ada world) complex objects implying multiple classes. BTW, thanks for bringing your C++ expertise on us poor Ada guyes, I really find your posts insightful on a lot of issues ;-). --LG