- Oberon - mailman3.inf.ethz.ch

Displacement vector in Mail.
by peter＠easthope.ca 16 Dec '23

16 Dec '23

Another detail I'm trying to understand. Mail.LoadMsgs declares a displacement vector, div. https://en.wikibooks.org/wiki/Oberon/A2/Oberon.Mail.Mod#div It's calculated here. https://en.wikibooks.org/wiki/Oberon/A2/Oberon.Mail.Mod#CalcDispVec A similar displacement vector is in the TextSearch further down in the module source. Search finds the location of a pattern. I don't understand why a displacement vector is needed. What is the role of the displacement vector. Thanks, ... P.L. -- VoIP: +1 604 670 0140 work: https://en.wikibooks.org/wiki/User:PeterEasthope

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Re: [Oberon] Recursion of inner procedures
by August Karlstrom 14 Dec '23

14 Dec '23

> On 2023-12-12 23:30, Diego Sardina wrote: > Recently I wrote to Wirth about this and he confirmed that inner > procedures can call themselves. > > How you would implement it? Introducing the procedure identifier in > the local scope with the possibility of shadowing it by another local > declaration? Of course in a clean way :-) We can maintain a stack of procedure identifiers which reflects the current procedure nesting. On a procedure call we look for the procedure identifier 1. in the current scope 2. on the top of the stack 3. in the global scope. Then a procedure like this will behave as expected: PROCEDURE Sum(a: ARRAY OF INTEGER; n: INTEGER): INTEGER; PROCEDURE Sum(a: ARRAY OF INTEGER; n, s: INTEGER): INTEGER; VAR result: INTEGER; BEGIN IF n > 0 THEN result := Sum(a, n - 1, s + a[n - 1]) ELSE result := s END RETURN result END Sum; RETURN Sum(a, n, 0) END Sum However, it may be more clear to use a distinct name for the local procedure. August

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Pattern pat in A2, Oberon.Mail.Mod.
by peter＠easthope.ca 13 Dec '23

13 Dec '23

Hi, In Oberon.Mail.Mod PROCEDURE LoadMsgs declares pat: ARRAY 8 OF CHAR; Then assigns 'pat := " From "; pat[0] := Strings.LF;' Ref. https://en.wikibooks.org/wiki/Oberon/A2/Oberon.Mail.Mod#pat After that pat[5] = " " and pat[6] = 0X. The pattern marks the beginning of each message in the MailMessages file. To my understanding pat[7] is never referenced. This declaration should suffice? pat: ARRAY 7 OF CHAR; After the assignment, pat doesn't change. Therefore make it a global variable in the module and assign the value in the module body? Thx, ... P.L. -- VoIP: +1 604 670 0140 work: https://en.wikibooks.org/wiki/User:PeterEasthope

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Re: [Oberon] Oberon-2 type bound procedure scope
by Andreas Pirklbauer 13 Dec '23

13 Dec '23

> August Karlstrom fusionfile at gmail.com > Tue Dec 12 22:26:58 CET 2023 > > As mentioned before, the Project Oberon 2013 compiler does not fully > conform to the language report. I don't know if it's due to lack of time > to make the changes to the compiler or if he want's the implementation > to be different. > > August That is correct. The PO 2013 does not fully conform to the language report in this respect. OTOH, it can be made conformant with a few lines of code in the compiler, as shown here: https://github.com/andreaspirklbauer/Oberon-no-access-to-intermediate-objec…

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Re: [Oberon] Oberon-2 type bound procedure scope
by Andreas Pirklbauer 13 Dec '23

13 Dec '23

> August Karlstrom fusionfile at gmail.com > Tue Dec 12 22:26:58 CET 2023 > > As mentioned before, the Project Oberon 2013 compiler does not fully > conform to the language report. I don't know if it's due to lack of time > to make the changes to the compiler or if he want's the implementation > to be different. > > August That is correct. The Project Oberon 2013 compiler does not fully conform to the language report in this respect. But it can be made conformant with just a few lines of code in the compiler: https://github.com/andreaspirklbauer/Oberon-no-access-to-intermediate-objec…

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Oberon-2 type bound procedure scope
by Stefano Ferrari 13 Dec '23

13 Dec '23

Consider a type bound procedure declaration PROCEDURE (tree: Tree) AddNode(node: Node); Where does the procedure scope start? Identifier ‘tree’ (receiver) belongs to the procedure scope, identifier ‘AddSymbol’ belongs to outer scope and then identifier ‘node’ belongs to procedure scope again Weird, isn’t it? Inviato da Posta per Windows

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Recursion of inner procedures
by Diego Sardina 12 Dec '23

12 Dec '23

I'm going to create a new thread since the previous one wasn't really in-topic. On Tue, Dec 12, 2023, at 20:16, Joerg wrote: > Not in NW‘s compiler. > Jörg > PO 2013 compiler is based on a 2008 Oberon07 report which had some experimental ideas such as arrays and procedure variables assignment by structure (and other things I don't remember). It wasn't updated since then. On Tue, Dec 12, 2023, at 22:37, August Karlstrom wrote: > On 2023-12-12 10:02, Diego Sardina wrote: >> In both cases not the best definition (what is the definition of >> environment? what is globally?), however since then only strictly >> local and strictly global objects are available to a procedure. > > I agree that it's not exactly clear exactly what "environment" is but > that word is no longer used in the language report. A "globally declared > object" on the other hand must be any object which is not local (to a > procedure). No ambiguity here that I can see. Which does not exclude intermediate global objects :-) at first reading it could just be seen as a better definition, a bit less problematic. On Tue, Dec 12, 2023, at 22:45, werner.heiz(a)gmail.com wrote: > Sorry, if I missed something, but if this local/global rule is strictly > applied without exception, recursive calls like this would not be allowed: > > PROCEDURE P; (*P is at scope level 0 = global scope *) > > PROCEDURE Q(n: INTEGER); (* Q is at scope level 1 (local to P); n is at > scope level 2 (local to Q) *) > BEGIN > IF n > 0 THEN DEC(n); Q(n) END; (* not allowed if rule strictly > applied as Q (scope level 1) is called from scope level 2 *) > END Q; > > BEGIN (*P*) > Q(10); > END P; > > I'm currently working on an Oberon compiler just for fun, and I think this > should be allowed. > Recently I wrote to Wirth about this and he confirmed that inner procedures can call themselves. How you would implement it? Introducing the procedure identifier in the local scope with the possibility of shadowing it by another local declaration? Of course in a clean way :-) -- Diego Sardina

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Re (4): HotKeys and SystemTools.
by peter＠easthope.ca 10 Dec '23

10 Dec '23

P.s. Correction: 3 different flavours of A2. The additional variable is the Debian release, 11 and 12. So four cases tried in total. ... P. -- VoIP: +1 604 670 0140 work: https://en.wikibooks.org/wiki/User:PeterEasthope

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Re (3): HotKeys and SystemTools.
by peter＠easthope.ca 10 Dec '23

10 Dec '23

Joerg & all, Four flavours of A2 tried here. All on Debian Linux on a Lenovo ThinkCentre. (1) Debian 11. LinuxA2 Gen. 64, rev.9799 released by Guenter. The Oberon subsystem works. No problem with the keyboard. According to the host console, HotKeys.Open executed and HotKeys.XML loaded. =8~) (2) Debian 12. LinuxA2 Gen. 64, rev.9799 released by Guenter. The A2 display is empty as described here. https://gitlab.inf.ethz.ch/felixf/oberon/-/issues/125 Something new in Linux? (3) Debian 12. LinuxA2 (64-bit, rev.10272) released by Guenter. No obvious problems in A2. With HotKeys disabled or not, F1, F2 and Delete do not work in the Oberon subsystem. (4) Debian 12. "LinuxA2 Gen. 64-bit, Apr 19 2023" started from the git repository. No obvious problems in A2. With HotKeys disabled or not, F1, F2 and Delete do not work in the Oberon subsystem. joerg.straube at iaeth.ch, Mon Dec 4 03:34:14 CET 2023 > Somebody must have edited Hotkeys.XML as the original that comes > with the A2 distribution assigns F12 to System.Free Hotkeys not > SystemTools.Free Thanks. Yes, the system has System.Free. Not SystemTools.Free. SystemTools is a distraction. =8~\ We might expect commenting out the HotKeys.Open command in the Autostart section of Configuration.XML to prevent interference with the Oberon keyboard. Doesn't. Appears that the problem is more fundamental. In the newer A2 systems, support for the Oberon keyboard is broken, independent of HotKeys. I don't know how the keyboard of the subsystem connects to the host A2. Therefore reluctant to start on a new study before another release is available. Thanks, ... P.L. -- VoIP: +1 604 670 0140 work: https://en.wikibooks.org/wiki/User:PeterEasthope

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Re (2): Re (2): HotKeys and SystemTools.
by peter＠easthope.ca 04 Dec '23

04 Dec '23

From: Joerg <joerg.straube(a)iaeth.ch> Date: Mon, 4 Dec 2023 07:34:14 +0500 > Edit it back and press F12 before starting Oberon. Can try that next weekend. Thx, ... P.L. -- VoIP: +1 604 670 0140 work: https://en.wikibooks.org/wiki/User:PeterEasthope

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