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,FREEMAIL_FROM autolearn=ham autolearn_force=no version=3.4.4 X-Google-Thread: 103376,66fae8c862b81b17 X-Google-NewGroupId: yes X-Google-Attributes: gida07f3367d7,domainid0,public,usenet X-Google-Language: ENGLISH,UTF8 Received: by 10.181.12.101 with SMTP id ep5mr1638664wid.1.1352304672467; Wed, 07 Nov 2012 08:11:12 -0800 (PST) Path: q13ni179480wii.0!nntp.google.com!feeder1.cambriumusenet.nl!feed.tweaknews.nl!194.134.4.91.MISMATCH!news2.euro.net!news.mixmin.net!aioe.org!.POSTED!not-for-mail From: =?utf-8?Q?Yannick_Duch=C3=AAne_=28Hibou57?= =?utf-8?Q?=29?= Newsgroups: comp.lang.ada Subject: Re: Copy vector in Ada Date: Wed, 07 Nov 2012 17:11:08 +0100 Organization: Ada @ Home Message-ID: References: <1aWdnbcg_8-BzAzNnZ2dnUVZ_j6dnZ2d@giganews.com> <6260a796-83c4-4ce5-88cb-8249846bc035@googlegroups.com> <10y91ckm54l57$.8u8bbq342u1b.dlg@40tude.net> <2164bc1a-a841-46ed-bfef-4ddcae4d64f7@googlegroups.com> <1ccf2169-418c-44b7-9d5a-b684a017fbe7@googlegroups.com> <1r3lpzblxy43h$.zytp8ur1bg27$.dlg@40tude.net> <1k3sjasg1wftm$.1vlq5hm7vukhk.dlg@40tude.net> <1sinhhpvja1gx.1ue7br8bz2slq$.dlg@40tude.net> <5098f58c$0$6558$9b4e6d93@newsspool4.arcor-online.net> <509a4dfb$0$6642$9b4e6d93@newsspool2.arcor-online.net> NNTP-Posting-Host: aWaWeUaBdaj2Zzc04J1v5A.user.speranza.aioe.org Mime-Version: 1.0 X-Complaints-To: abuse@aioe.org User-Agent: Opera Mail/12.02 (Linux) X-Notice: Filtered by postfilter v. 0.8.2 Content-Type: text/plain; charset=utf-8; format=flowed; delsp=yes Content-Transfer-Encoding: Quoted-Printable Date: 2012-11-07T17:11:08+01:00 List-Id: Le Wed, 07 Nov 2012 13:03:08 +0100, Georg Bauhaus = a =C3=A9crit: > On 06.11.12 20:47, Yannick Duch=C3=AAne (Hibou57) wrote: >> Now, talking about proper naming of things, how would you explain to = a >> student, that sometime =E2=80=9Ctype=E2=80=9D must follow the substit= ution principle, = >> and >> sometime, it do exactly the opposite? > > The challenge is to explain why the substitution principle is > a valid commandment: A valuable piece of formal theory, it may > not offer sufficient justification in the workplace. It was never promoted as a commandment in my comments, but said it is no= t = to be confused to something else, and to be followed when expected, and = = not followed when not applicable (like not using it in place of reuse, = because this always gives the illusion of one thing and give another = instead). This find as much justifications as predictability do. > Why? Because the workplace is governed by rules that language > theory/ideology/religion/principles will not normally cover. No religion/ideology was spread, but some basic principle recalled. > A similar example will explain why principles like a theoretically > clean notion may turn out to be pointless, even a hindrance once > they are used outside the clean room: > > Sometimes programs would modify themselves in a perfectly, > provably safe way, leading to sufficient performance in > terms of time and storage. And no matter what one might have > to say about their design, only by violating today's principles > could they achieve their stated goals. Today, it may not even > be possible to run such programs, because modifications are > detected, and the program is stopped. Principles have changed. And that's precisely because we don't have proved things, we need guidan= ce = to prevent errors. Typing and other rules are kind of minimalist and = default proofs of some properties. And this is there by the lack of bett= er = (there are other techniques, but so tedious and time consuming to apply,= = they would prevent many thing to be done, so these techniques are = restricted to some area). > But are these self-modifying programs not "programs" anymore > because they were "improperly named `programs'"? That's unfair, you are drifting too much based on a single definition I = = maid. By the way, I would call these =E2=80=9Dprograms=E2=80=9C, so you = did not properly = guess. > Similarly, I'll say that "inheritance" without further adjectives > is just insufficiently defined, and void of purpose (for the > workplace). And any single definition cannot name the "right" > inheritance. > > So we have > "Thou shalt follow the substitution principle!" > and > "today's orthodoxy of language theory". > > (Well, actually, the 1980s' theory, or even earlier.) You should know some old things are still valid today ;) -- = =E2=80=9CSyntactic sugar causes cancer of the semi-colons.=E2=80=9D [1] =E2=80=9CStructured Programming supports the law of the excluded muddle.= =E2=80=9D [1] [1]: Epigrams on Programming =E2=80=94 Alan J. =E2=80=94 P. Yale Univers= ity