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: a07f3367d7,dbbbb21ed7f581b X-Google-Attributes: gida07f3367d7,public,usenet X-Google-NewGroupId: yes X-Google-Language: ENGLISH,ASCII-7-bit Path: g2news1.google.com!news4.google.com!feeder1.cambriumusenet.nl!feed.tweaknews.nl!216.196.110.149.MISMATCH!border2.nntp.ams.giganews.com!nntp.giganews.com!feed.xsnews.nl!feeder.xsnews.nl!151.189.20.20.MISMATCH!newsfeed.arcor.de!newsspool3.arcor-online.net!news.arcor.de.POSTED!not-for-mail From: "Dmitry A. Kazakov" Subject: Re: Operation can be dispatching in only one type Newsgroups: comp.lang.ada User-Agent: 40tude_Dialog/2.0.15.1 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: <025105f2-5571-400e-a66f-ef1c3dc9ef32@g27g2000yqn.googlegroups.com> <1iipp3bn16fe2.yqa1gz1ru17a$.dlg@40tude.net> <18wh86jvjvoe0.cofxcc8udm6q$.dlg@40tude.net> <53a35ed9-88ac-43dc-b2a2-8d6880802328@j19g2000yqk.googlegroups.com> <4b091fb9$0$6567$9b4e6d93@newsspool4.arcor-online.net> <1w0q3zxzw79pt$.5z0juiky7kfd$.dlg@40tude.net> <0f177771-381e-493b-92bb-28419dfbe4e6@k19g2000yqc.googlegroups.com> <1nbcfi99y0fkg.1h5ox2lj73okx$.dlg@40tude.net> <59acf311-3a4a-4eda-95a3-22272842305e@m16g2000yqc.googlegroups.com> <3pvk14f2iizi$.b3u242o1oqla.dlg@40tude.net> <15b8l0vp8871o.spmxnk82g75r.dlg@40tude.net> Date: Tue, 1 Dec 2009 12:12:10 +0100 Message-ID: NNTP-Posting-Date: 01 Dec 2009 12:12:10 CET NNTP-Posting-Host: 842c0e0b.newsspool2.arcor-online.net X-Trace: DXC=Y:U2oC>aIbXV;Ef1`Jk54\A9EHlD;3YcR4Fo<]lROoRQ8kF_hP7Je^^ehF^ X-Complaints-To: usenet-abuse@arcor.de Xref: g2news1.google.com comp.lang.ada:8261 Date: 2009-12-01T12:12:10+01:00 List-Id: On Tue, 1 Dec 2009 06:45:16 +0100, stefan-lucks@see-the.signature wrote: > On Tue, 1 Dec 2009, Dmitry A. Kazakov wrote: > >> On Mon, 30 Nov 2009 15:43:21 -0500, Robert A Duff wrote: > >>> Right. I think they should be equivalent. My solution is to use >>> two different symbols for (initial) assignment and (subsequent) >>> reassignment. >> >> But they cannot be, otherwise the semantics of ":=" would depend on the >> things done before: >> >> X : T; >> begin >> X := F (Y); -- Initialization > > No, at this point of time, X has been initialised to *some* value, even if > the value itself is undefined. So this is just a proper assignment. You should say that to Bob, because this is exactly my point. An object is *always* constructed <=> initialized before it can ever be used in any way (provided the language is typed <=> at any point of its existence any object has a definite type and only the operations defined for the type are available to the object). Initialization /= construction does not fit into this picture. >> X : T; >> begin >> X := Z; >> X := F (Y); -- [Re]assignment > > That is a proper assignment, as well. The only difference is that we > can be sure the before-assignment value of X is defined (assuming the > value of Z is a defined one). > > An initialisation would be > > X : T ::= F(Y); > begin > ... > > But you are right, Dmitry, nobody would not want to distinguish an > assignment to overwrite a potentially undefined value from an assignment > ovwerwriting a previously defined value. Of course I am! (:-)) -- Regards, Dmitry A. Kazakov http://www.dmitry-kazakov.de