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-Thread: 103376,8ca14c11fd6d2e56 X-Google-Attributes: gid103376,public X-Google-Language: ENGLISH,ASCII-7-bit Path: g2news1.google.com!news1.google.com!newsread.com!news-xfer.newsread.com!newspeer.monmouth.com!newsfeed.icl.net!newsfeed.fjserv.net!newsfeed.freenet.de!newsfeed.arcor.de!news.arcor.de!not-for-mail From: "Dmitry A. Kazakov" Subject: Re: generic parameter Copy for primitifs types. Newsgroups: comp.lang.ada User-Agent: 40tude_Dialog/2.0.14.1 MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Reply-To: mailbox@dmitry-kazakov.de Organization: cbb software GmbH References: <1119544911.159343.288010@g43g2000cwa.googlegroups.com> <837ivwsz8r2d$.j16zz1529zb9$.dlg@40tude.net> <1119555704.527944.224770@g49g2000cwa.googlegroups.com> <1ormc6uaytixb.v2ogsw0x6y8k.dlg@40tude.net> Date: Fri, 24 Jun 2005 16:53:54 +0200 Message-ID: <1rjzmqwb7teen.6jbixg07vhn5.dlg@40tude.net> NNTP-Posting-Date: 24 Jun 2005 16:53:57 MEST NNTP-Posting-Host: 52b2e79c.newsread2.arcor-online.net X-Trace: DXC=:oO:2KB4OJDo47S\@TX3oEQ5U85hF6f;DjW\KbG]kaMHXSE8@R32 On Fri, 24 Jun 2005 12:45:19 +0100, Marius Amado Alves wrote: > On 24 Jun 2005, at 08:28, Dmitry A. Kazakov wrote: >>> The best solution is to set ":=" by default but it >>> is not possible... >> >> True. You can try generic "specialization" like this: >> ... >> generic >> type T_Item is private; >> package Specialized_Toto is >> procedure Copy (Left : out T_Item; Right : T_Item); >> package Toto_Instance is new Toto (T_Item, Copy); >> end Specialized_Toto; >> ... > > True. But then the use is not uniform. A different generic package must > be selected for each case: > > package Default_Pkg is new Specialized_Toto (T); > package Special_Pkg is new Toto (T, Special_Copy); > > The idiom I have posted earlier does not have this problem. But, > granted, may have others instead, e.g. requiring two instantiations > instead of one for each case. > > All this would go away if packages were first class citizens of Ada, > i.e. objects. This is one thing I'm trying to do with Ocpotus > (softdevelcoop.org/ocpotus). Or - if true package specialization were available; - if generic types were ADT (you could have generic formal types of your own); - if assignment were a primitive operation (discriminants/constraints problem is solvable, IMO); - etc. Packages as objects is a fundamental question I believe. A potential danger is that when packages become objects any difference between "type" and "package" might disappear. The result would be a type system close to C++. But we know that C++ has immense problems in the elaboration model, or better to say with absence of any model. Is it curable? I can't tell. If Robert Dewar were here, he would probably shed more light on the mechanics. -- Regards, Dmitry A. Kazakov http://www.dmitry-kazakov.de